Publikacje odnotowane przez trzy miesiące

1.Taczała M., Buczkowski R., Kleiber M., Nonlinear buckling and post-buckling response of stiffened FGM plates in thermal environments, COMPOSITES PART B-ENGINEERING, ISSN: 1359-8368, DOI: 10.1016/j.compositesb.2016.09.023, Vol.109, pp.238-247, 2017
Taczała M., Buczkowski R., Kleiber M., Nonlinear buckling and post-buckling response of stiffened FGM plates in thermal environments, COMPOSITES PART B-ENGINEERING, ISSN: 1359-8368, DOI: 10.1016/j.compositesb.2016.09.023, Vol.109, pp.238-247, 2017

Abstract:
We present a nonlinear finite element method to investigate the nonlinear stability of stiffened functionally graded materials (FGM) plates considered as a whole unit. The plates are subjected to mechanical and thermal loads. The material properties are assumed to be temperature dependent and varied gradually across the thickness according to a power law distribution. The nonlinear equations of FGM plates are based on the first-order shear order plate theory. The influence of material, geometrical properties of stiffeners and initial deflections on the buckling and post-buckling response of the stiffened plates are studied in detail. Including the latest information no work has been oriented towards post-buckling analysis of stiffened FGM plates considered as a whole unit.

Keywords:
FGM stiffened plate, nonlinear finite element analysis, post-buckling

(45p.)
2.Adimy M., Chekroun A., Kaźmierczak B., Traveling waves in a coupled reaction–diffusion and difference model of hematopoiesis, Journal of Differential Equations, ISSN: 0022-0396, DOI: 10.1016/j.jde.2016.12.009, Vol.262, No.7, pp.4085-4128, 2017
Adimy M., Chekroun A., Kaźmierczak B., Traveling waves in a coupled reaction–diffusion and difference model of hematopoiesis, Journal of Differential Equations, ISSN: 0022-0396, DOI: 10.1016/j.jde.2016.12.009, Vol.262, No.7, pp.4085-4128, 2017

Abstract:
The formation and development of blood cells is a very complex process, called hematopoiesis. This process involves a small population of cells called hematopoietic stem cells (HSCs). The HSCs are undifferentiated cells, located in the bone marrow before they become mature blood cells and enter the blood stream. They have a unique ability to produce either similar cells (self-renewal), or cells engaged in one of different lineages of blood cells: red blood cells, white cells and platelets (differentiation). The HSCs can be either in a proliferating or in a quiescent phase. In this paper, we distinguish between dividing cells that enter directly to the quiescent phase and dividing cells that return to the proliferating phase to divide again. We propose a mathematical model describing the dynamics of HSC population, taking into account their spatial distribution. The resulting model is a coupled reaction–diffusion equation and difference equation with delay. We study the existence of monotone traveling wave fronts and the asymptotic speed of spread.

Keywords:
Hematopoiesis, Age-structured population, Reaction–diffusion system with delay, Difference equation, Traveling wave front, Asymptotic speed of spread

(45p.)
3.Kochańczyk M., Kocieniewski P., Kozłowska E., Jaruszewicz-Błońska J., Sparta B., Pargett M., Albeck J.G., Hlavacek W.S., Lipniacki T., Relaxation oscillations and hierarchy of feedbacks in MAPK signaling, Scientific Reports, ISSN: 2045-2322, DOI: 10.1038/srep38244, Vol.7, No.38244, pp.1-15, 2017
Kochańczyk M., Kocieniewski P., Kozłowska E., Jaruszewicz-Błońska J., Sparta B., Pargett M., Albeck J.G., Hlavacek W.S., Lipniacki T., Relaxation oscillations and hierarchy of feedbacks in MAPK signaling, Scientific Reports, ISSN: 2045-2322, DOI: 10.1038/srep38244, Vol.7, No.38244, pp.1-15, 2017

Abstract:
We formulated a computational model for a MAPK signaling cascade downstream of the EGF receptor to investigate how interlinked positive and negative feedback loops process EGF signals into ERK pulses of constant amplitude but dose-dependent duration and frequency. A positive feedback loop involving RAS and SOS, which leads to bistability and allows for switch-like responses to inputs, is nested within a negative feedback loop that encompasses RAS and RAF, MEK, and ERK that inhibits SOS via phosphorylation. This negative feedback, operating on a longer time scale, changes switch-like behavior into oscillations having a period of 1 hour or longer. Two auxiliary negative feedback loops, from ERK to MEK and RAF, placed downstream of the positive feedback, shape the temporal ERK activity profile but are dispensable for oscillations. Thus, the positive feedback introduces a hierarchy among negative feedback loops, such that the effect of a negative feedback depends on its position with respect to the positive feedback loop. Furthermore, a combination of the fast positive feedback involving slow-diffusing membrane components with slower negative feedbacks involving faster diffusing cytoplasmic components leads to local excitation/global inhibition dynamics, which allows the MAPK cascade to transmit paracrine EGF signals into spatially non-uniform ERK activity pulses.

Keywords:
MAPK signaling, Oscillations, Mathematical modelling

(40p.)
4.Gradys A., Geometrical effects during crystallization under confinement in electrospun core-shell fibers. DSC study of crystallization kinetics, POLYMER, ISSN: 0032-3861, DOI: 10.1016/j.polymer.2016.12.009, Vol.108, pp.383-394, 2017
Gradys A., Geometrical effects during crystallization under confinement in electrospun core-shell fibers. DSC study of crystallization kinetics, POLYMER, ISSN: 0032-3861, DOI: 10.1016/j.polymer.2016.12.009, Vol.108, pp.383-394, 2017

Abstract:
Calorimetric studies on poly(ethylene glycol) Mn = 400 g/mol, encapsulated in polystyrene fibers show non-trivial crystallization behavior. Analysis, assuming constant Avrami exponent n, is unsuitable. Approach allowing for changes in the exponent n, requires assumption of the crystallization rate function, derived from the nucleation theory. Changes in Avrami exponent n, follow the changes in geometry of crystal growth and in nucleation mechanisms. Crystallization in micrometer fibers starts from heterogeneous nucleation with three-dimensional crystal growth e as in bulk e but changes to two and one-dimensional, terminated by homogeneous nucleation. For bulk and in 1 and 0.6 micron thick fibers, the approach evidences similar thermodynamic parameters. In 0.6 micron thick fibers, crystallization rate is lower due to higher energy barrier for diffusion, ED = 10 kJ/mol versus 8.7 kJ/mol for bulk and 1 micron thick fibers. Additionally, fiber thickness depends not only on parameters of the electrospinning process but also on the thermal history.

Keywords:
Core-shell fibers, Confinement effects, Crystallization kinetics, DSC, Polyethylene glycol

(40p.)
5.Krajewski M., Lee P.H., Wu S.H., Brzozka K., Małolepszy A., Stobiński L., Tokarczyk M., Kowalski G., Wąsik D., Nanocomposite composed of multiwall carbon nanotubes covered by hematite nanoparticles as anode material for Li-ion batteries, Electrochimica Acta, ISSN: 0013-4686, DOI: 10.1016/j.electacta.2017.01.051, Vol.228, pp.82-90, 2017
Krajewski M., Lee P.H., Wu S.H., Brzozka K., Małolepszy A., Stobiński L., Tokarczyk M., Kowalski G., Wąsik D., Nanocomposite composed of multiwall carbon nanotubes covered by hematite nanoparticles as anode material for Li-ion batteries, Electrochimica Acta, ISSN: 0013-4686, DOI: 10.1016/j.electacta.2017.01.051, Vol.228, pp.82-90, 2017

Abstract:
This work describes the detailed studies performed on the nanocomposite composed of chemically-modified multiwall carbon nanotubes covered by hematite nanoparticles which diameters vary from 10 nm to 70 nm. This nanomaterial was fabricated in two-steps facile chemical synthesis and was characterized with the use of several experimental techniques, such as: thermogravimetric analysis, differential thermal analysis, Raman spectroscopy, X-ray diffraction, and transmission Mössbauer spectroscopy in order to determine its structure precisely. Moreover, the investigated nanocomposite was tested as an anode material of Li-ion batteries. Its cycling performance was stable during 40 cycles, while its capacity was retained at the level of 330 and 230 mAh/g at the discharge/charge rate of 25 and 200 mA/g, respectively.

Keywords:
anode material, hematite, Li-ion battery, multiwall carbon nanotube, nanocomposite

(40p.)
6.Jarząbek D.M., Milczarek M., Wojciechowski T., Dziekoński C., Chmielewski M., The effect of metal coatings on the interfacial bonding strength of ceramics to copper in sintered Cu-SiC composites, CERAMICS INTERNATIONAL, ISSN: 0272-8842, DOI: 10.1016/j.ceramint.2017.01.056, pp.1-9, 2017
Jarząbek D.M., Milczarek M., Wojciechowski T., Dziekoński C., Chmielewski M., The effect of metal coatings on the interfacial bonding strength of ceramics to copper in sintered Cu-SiC composites, CERAMICS INTERNATIONAL, ISSN: 0272-8842, DOI: 10.1016/j.ceramint.2017.01.056, pp.1-9, 2017

Abstract:
Cu-SiC composites are very promising materials which have high thermal and electrical conductivity and may find many applications. Unfortunately, the main disadvantage of these materials is the dissolution of silicon in copper at elevated temperature, which significantly reduces their properties. In order to overcome this problem particles can be coated with a protective material before sintering. In this paper– the influence of three different metallic coatings on bonding strength were investigated. SiC particles were coated with tungsten, chromium or titanium. As reference a material with uncoated particles was prepared. The experiments were carried out with the use of microtensile tester. The highest increase in strength was observed in the case of chromium coating. On the other hand, the titanium coating, which was of very poor quality, decrease the bonding strength in comparison with uncoated particles. Furthermore, scanning electron and optical microscopes were used to determine the mechanism of debonding.

Keywords:
Interfacial bonding strength, Metal matrix composites, Tensile strength, Silicon carbide particles

(40p.)
7.Leyva-Mendivil M.F., Lengiewicz J., Page A., Bressloff N.W., Limbert G., Skin Microstructure is a Key Contributor to Its Friction Behaviour, TRIBOLOGY LETTERS, ISSN: 1023-8883, DOI: 10.1007/s11249-016-0794-4, Vol.65, No.12, pp.1-17, 2017
Leyva-Mendivil M.F., Lengiewicz J., Page A., Bressloff N.W., Limbert G., Skin Microstructure is a Key Contributor to Its Friction Behaviour, TRIBOLOGY LETTERS, ISSN: 1023-8883, DOI: 10.1007/s11249-016-0794-4, Vol.65, No.12, pp.1-17, 2017

Abstract:
Due to its multifactorial nature, skin friction remains a multiphysics and multiscale phenomenon poorly understood despite its relevance for many biomedical and engineering applications (from superficial pressure ulcers, through shaving and cosmetics, to automotive safety and sports equipment). For example, it is unclear whether, and in which measure, the skin microscopic surface topography, internal microstructure and associated nonlinear mechanics can condition and modulate skin friction. This study addressed this question through the development of a parametric finite element contact homogenisation procedure which was used to study and quantify the effect of the skin microstructure on the macroscopic skin frictional response. An anatomically realistic two-dimensional image-based multilayer finite element model of human skin was used to simulate the sliding of rigid indenters of various sizes over the skin surface. A corresponding structurally idealised multilayer skin model was also built for comparison purposes. Microscopic friction specified at skin asperity or microrelief level was an input to the finite element computations. From the contact reaction force measured at the sliding indenter, a homogenised (or apparent) macroscopic friction was calculated. Results demonstrated that the naturally complex geometry of the skin microstructure and surface topography alone can play as significant role in modulating the deformation component of macroscopic friction and can significantly increase it. This effect is further amplified as the ground-state Young’s modulus of the stratum corneum is increased (for example, as a result of a dryer environment). In these conditions, the skin microstructure is a dominant factor in the deformation component of macroscopic friction, regardless of indenter size or specified local friction properties. When the skin is assumed to be an assembly of nominally flat layers, the resulting global coefficient of friction is reduced with respect to the local one. This seemingly counter-intuitive effect had already been demonstrated in a recent computational study found in the literature. Results also suggest that care should be taken when assigning a coefficient of friction in computer simulations, as it might not reflect the conditions of microscopic and macroscopic friction one intends to represent. The modelling methodology and simulation tools developed in this study go beyond what current analytical models of skin friction can offer: the ability to accommodate arbitrary kinematics (i.e. finite deformations), nonlinear constitutive properties and the complex geometry of the skin microstructural constituents. It was demonstrated how this approach offered a new level of mechanistic insight into plausible friction mechanisms associated with purely structural effects operating at the microscopic scale; the methodology should be viewed as complementary to physical experimental protocols characterising skin friction as it may facilitate the interpretation of observations and measurements and/or could also assist in the design of new experimental quantitative assays.

Keywords:
Skin, Friction mechanisms, Contact mechanics, Microstructure, Finite element, Image-based modelling, Material properties

(35p.)
8.Kiełczyński P., Szalewski M., Balcerzak A., Wieja K., Rostocki A., Ptasznik S., Evaluation of High-Pressure Thermophysical Parameters of the Diacylglycerol (DAG) Oil Using Ultrasonic Waves, Food and Bioprocess Technology, ISSN: 1935-5130, DOI: 10.1007/s11947-016-1827-6, Vol.10, No.2, pp.358-369, 2017
Kiełczyński P., Szalewski M., Balcerzak A., Wieja K., Rostocki A., Ptasznik S., Evaluation of High-Pressure Thermophysical Parameters of the Diacylglycerol (DAG) Oil Using Ultrasonic Waves, Food and Bioprocess Technology, ISSN: 1935-5130, DOI: 10.1007/s11947-016-1827-6, Vol.10, No.2, pp.358-369, 2017

Abstract:
Modeling of high-pressure technological processes in the food industry requires knowledge of thermophysical parameters of processed foodstuffs in a broad range of pressures and temperatures. However, the high-pressure thermophysical parameters of foodstuffs are very rarely published in the literature. Therefore, further research is necessary to achieve a deeper insight into the biophysical and thermophysical phenomena under pressure to provide better control of technological processes and optimize the effects of pressure. The essential goal of this work is to evaluate the impact of high pressure and temperature on the thermophysical parameters of liquid foodstuffs on the example of diacylglycerol (DAG) oil (which attracted recently a considerable attention from research and industrial communities due to its remarkable benefits for health), using ultrasonic wave velocity and density measurements. Isotherms of adiabatic and isothermal compressibility, isobaric thermal expansion coefficient, internal pressure, and thermal pressure coefficient versus pressure were evaluated, based on the measurement of the compressional ultrasonic wave velocity and density of DAG oil at high pressures (up to 500 MPa) and at various temperatures. The adiabatic compressibility is affected mostly by the changes of pressure, i.e., it grows about four times when the pressure increases from the atmospheric pressure (0.1 MPa) to 400 MPa at a temperature of 50 °C. By contrast, the internal pressure is a pronounced function of the temperature, i.e., it increases six times when the temperature rises from 20 to 50 °C at a pressure of a 200 MPa. To perform numerical calculations, it was convenient to introduce a Tammann–Tait type equation of state to approximate the measured density isotherms of the investigated DAG oil. The results obtained in this paper can be applied in modeling and optimization of high-pressure technological processes and processing of foodstuffs. Evaluation of high-pressure isotherms of the considered thermophysical parameters of the DAG oil is an original authors’ contribution to the state-of-the-art.

Keywords:
High-pressure food processing, Diacylglycerols, Thermophysical parameters, Isothermal compressibility, Isobaric thermal expansion coefficient, Ultrasonic methods

(35p.)
9.Hoffman J., Chrzanowska J., Mościcki T., Radziejewska J., Stobinski L., Szymański Z., Plasma generated during underwater pulsed laser processing, APPLIED SURFACE SCIENCE, ISSN: 0169-4332, DOI: 10.1016/j.apsusc.2017.01.185, pp.1-6, 2017
Hoffman J., Chrzanowska J., Mościcki T., Radziejewska J., Stobinski L., Szymański Z., Plasma generated during underwater pulsed laser processing, APPLIED SURFACE SCIENCE, ISSN: 0169-4332, DOI: 10.1016/j.apsusc.2017.01.185, pp.1-6, 2017

Abstract:
The plasma induced during underwater pulsed laser ablation of graphite is studied both experimentally and theoretically. The results of the experiment show that the maximum plasma temperature of 25000 K is reached 20 ns from the beginning of the laser pulse and decreases to 6500 K after 1000 ns. The observed OH absorption band shows that the plasma plume is surrounded by the thin layer of dissociated water vapour at a temperature around 5500 K. The hydrodynamic model applied shows similar maximum plasma temperature at delay times between 14 ns and 30 ns. The calculations show also that already at 14th ns, the plasma electron density reaches 0.97·1027 m−3, which is the critical density for 1064 nm radiation. At the same time the plasma pressure is 2 GPa, which is consisted with earlier measurements of the peak pressure exerted on a target in similar conditions.

Keywords:
Underwater laser processing, Pulsed laser ablation in liquid, Laser induced plasma, Numerical modelling

(35p.)
10.Pakdel A., Witecka A., Rydzek G., Shri D.N.A., A comprehensive microstructural analysis of Al–WC micro- and nano-composites prepared by spark plasma sintering, MATERIALS AND DESIGN, ISSN: 0261-3069, DOI: 10.1016/j.matdes.2017.01.064, Vol.119, pp.225-234, 2017
Pakdel A., Witecka A., Rydzek G., Shri D.N.A., A comprehensive microstructural analysis of Al–WC micro- and nano-composites prepared by spark plasma sintering, MATERIALS AND DESIGN, ISSN: 0261-3069, DOI: 10.1016/j.matdes.2017.01.064, Vol.119, pp.225-234, 2017

Abstract:
There have been many investigations on metal matrix microcomposites produced by conventional casting routes; however, in the past decade, the focus has shifted more toward nanocomposites produced via solid state routes. To have a realistic view of performance prediction and optimum design of such composites, in this work Al matrix composites (AMCs) reinforced with WC microparticles, nanoparticles, and bimodal micro-/nano-particles were prepared by spark plasma sintering. The effects of particle size and concentration, and process variables (i.e. sintering temperature, duration, and pressure) on the evolution of microstructure, density and hardness of the composites were studied comprehensively. Full densification of AMCs with high particle concentration was problematic because of ceramic cluster formations in the microstructure. This effect was more emphasized in AMCs containing nanoparticles. AMCs with microparticles were more easily densified, but their hardness benefits were inferior. On the other hand, the mixture of micro- and nano-particles in Al-WC bimodal composites led to better matrix reinforcement integrity and an overall improvement in the microstructural properties. Finally, increasing the sintering temperature improved the microstructural features and hardness of the composites (more enhanced in high wt.% samples), but sintering duration and pressure did not have a big impact on the composite properties.

Keywords:
Composite, Nanoparticle, Microparticle, Powder metallurgy, SPS, Microstructure

(35p.)
11.Bajer C.I., Pisarski D., Szmidt T., Dyniewicz B., Intelligent damping layer under a plate subjected to a pair of masses moving in opposite directions, JOURNAL OF SOUND AND VIBRATION, ISSN: 0022-460X, DOI: 10.1016/j.jsv.2017.01.046, pp.1-15, 2017
Bajer C.I., Pisarski D., Szmidt T., Dyniewicz B., Intelligent damping layer under a plate subjected to a pair of masses moving in opposite directions, JOURNAL OF SOUND AND VIBRATION, ISSN: 0022-460X, DOI: 10.1016/j.jsv.2017.01.046, pp.1-15, 2017

Abstract:
Reducing displacements of a plate vibrating under a pair of masses traveling in opposite directions can be improved by adding a smart subsoil instead of a classical damping layer. We propose a material that acts according to the instantaneous state of the plate, i.e., its displacements and velocity. Such an intelligent damping layer reduces vertical displacements even by 40%–60%, depending on the type of load and the assumed objective function. Existing materials enable the application of the proposed layer in a semi-active mode. The passive mode can be applied with materials exhibiting direction-dependent viscosity.

Keywords:
Plate vibration; Moving load; Intelligent damping layer; Semi-active damping

(35p.)
12.Petryk H., Stupkiewicz S., Kucharski S., On direct estimation of hardening exponent in crystal plasticity from the spherical indentation test, INTERNATIONAL JOURNAL OF SOLIDS AND STRUCTURES, ISSN: 0020-7683, DOI: 10.1016/j.ijsolstr.2016.09.025, pp.1-13, 2017
Petryk H., Stupkiewicz S., Kucharski S., On direct estimation of hardening exponent in crystal plasticity from the spherical indentation test, INTERNATIONAL JOURNAL OF SOLIDS AND STRUCTURES, ISSN: 0020-7683, DOI: 10.1016/j.ijsolstr.2016.09.025, pp.1-13, 2017

Abstract:
A novel methodology is proposed for estimating the strain hardening exponent of a metal single crystal directly from the spherical indentation test, without the need of solving the relevant inverse problem. The attention is focused on anisotropic piling-up and sinking-in that occur simultaneously in different directions, in contrast to the standard case of axial symmetry for isotropic materials. To correlate surface topography parameters with the value of material hardening exponent, a finite-element study of spherical indentation has been performed within a selected penetration depth range using a finite-strain crystal plasticity model. It is shown how the power-law hardening exponent can be estimated from the measured pile-up/sink-in pattern around the residual impression after indentation in a (001)-oriented fcc single crystal of a small initial yield stress. For this purpose, a new parameter of surface topography is defined as the normalized material volume displaced around the nominal contact zone, calculated by integration of the local residual height (positive or negative) over a centered circular ring. That indicator can be easily determined from an experimental topography map available in a digital form. Comparison is made with the estimates based on measurements of the contact area and the slope of the load–penetration depth curve in logarithmic coordinates. The proposed methodology is extended to estimation of the hardening exponent simultaneously with the initial yield stress when the latter is not negligible. Experimental verification for a Cu single crystal leads to promising conclusions.

Keywords:
Metal crystal, Elastoplasticity, Finite deformation, Strain hardening, Experimental identification

(35p.)
13.Wójcik J., Lewandowski M., Żołek N., Grating Lobes Suppression by Adding Virtual Receiving Subaperture in Synthetic Aperture Imaging, Ultrasonics, ISSN: 0041-624X, DOI: 10.1016/j.ultras.2016.12.013, Vol.76, pp.125-135, 2017
Wójcik J., Lewandowski M., Żołek N., Grating Lobes Suppression by Adding Virtual Receiving Subaperture in Synthetic Aperture Imaging, Ultrasonics, ISSN: 0041-624X, DOI: 10.1016/j.ultras.2016.12.013, Vol.76, pp.125-135, 2017

Abstract:
A method of suppression of grating lobes is presented, analyzed, and verified. The method is based on creating a Virtual Receiving Subaperture (VRS) by adding virtual transducer elements not existing in the physical layout of the receiver. The VRS channels are filled with data based on signals from real channels. The analytical model of the synthetic aperture imaging system’s impulse response is presented to describe the properties of the VRS. The model shows a reduction of the receiving grating lobes’ amplitude (with a comparison to the main lobe’s amplitude) by a magnitude equal to the number of receiving transducer elements. It is shown that effective properties of the entire system with a VRS are similar to a system with a pitch in the receiving aperture that is twice as small. The numerical calculations of the impulse response show a doubling of the signal to noise ratio, which results in a reduction of the receiving grating lobes. For experimental validation, the generalized Plane Wave Imaging with and without the VRS is compared with a basic synthetic transmit aperture (STA) imaging. The experiment confirmed that the use of a VRS allows for visualizat ion of the objects in a medium in which they are not imaged without a VRS or are visualized with a lower contrast. The reduction of grating lobes attained using the proposed method is at the level of 15dB in the visualization of the superficial cyst.

Keywords:
Grating lobes, Image quality, Synthetic aperturę, Virtual subaperture

(30p.)
14.Michajłow M., Jankowski Ł., Szolc T., Konowrocki R., Semi-active reduction of vibrations in the mechanical system driven by an electric motor, OPTIMAL CONTROL APPLICATIONS & METHODS, ISSN: 0143-2087, DOI: 10.1002/oca.2297, pp.1-12, 2017
Michajłow M., Jankowski Ł., Szolc T., Konowrocki R., Semi-active reduction of vibrations in the mechanical system driven by an electric motor, OPTIMAL CONTROL APPLICATIONS & METHODS, ISSN: 0143-2087, DOI: 10.1002/oca.2297, pp.1-12, 2017

Abstract:
In this paper, a semi-active damping approach is used for reduction of vibrations in a laboratory drivetrain system. The considered drivetrain system is powered by an electric, asynchronous motor at the one side and loaded with a harmonically varying torque on the other side. Here, an influence of electromechanical interaction, i.e., an electromechanical coupling, between the electric motor and the mechanical system has been taken into consideration. The harmonic load signal induces torsional vibrations in the system, which in the steady-state phase of motion become periodic. The aim of the work is to determine the optimal control function for a semi-active damping element, leading to vibration reduction and considering only the steady-state phase of system motion. The optimal control is derived by using a semi-analytical approach based on the optimal control theory aided with supplementary numerical computations. The proposed methodology is fully general, and it can be directly applied to any type of a periodically oscillating system.

Keywords:
electric motor, electromechanical coupling, optimal control, periodic torsional vibrations, semi-active damping

(30p.)
15.Kujawska T., Secomski W., Byra M., Postema M., Nowicki A., Annular phased array transducer for preclinical testing of anti-cancer drug efficacy on small animals, Ultrasonics, ISSN: 0041-624X, DOI: 10.1016/j.ultras.2016.12.008, Vol.76, pp.92-98, 2017
Kujawska T., Secomski W., Byra M., Postema M., Nowicki A., Annular phased array transducer for preclinical testing of anti-cancer drug efficacy on small animals, Ultrasonics, ISSN: 0041-624X, DOI: 10.1016/j.ultras.2016.12.008, Vol.76, pp.92-98, 2017

Abstract:
A technique using pulsed High Intensity Focused Ultrasound (HIFU) to destroy deep-seated solid tumors is a promising noninvasive therapeutic approach. A main purpose of this study was to design and test a HIFU transducer suitable for preclinical studies of efficacy of tested, anti-cancer drugs, activated by HIFU beams, in the treatment of a variety of solid tumors implanted to various organs of small animals at the depth of the order of 1–2 cm under the skin. To allow focusing of the beam, generated by such transducer, within treated tissue at different depths, a spherical, 2-MHz, 29-mm diameter annular phased array transducer was designed and built. To prove its potential for preclinical studies on small animals, multiple thermal lesions were induced in a pork loin ex vivo by heating beams of the same: 6 W, or 12 W, or 18 W acoustic power and 25 mm, 30 mm, and 35 mm focal lengths. Time delay for each annulus was controlled electronically to provide beam focusing within tissue at the depths of 10 mm, 15 mm, and 20 mm. The exposure time required to induce local necrosis was determined at different depths using thermocouples. Location and extent of thermal lesions determined from numerical simulations were compared with those measured using ultrasound and magnetic resonance imaging techniques and verified by a digital caliper after cutting the tested tissue samples. Quantitative analysis of the results showed that the location and extent of necrotic lesions on the magnetic resonance images are consistent with those predicted numerically and measured by caliper. The edges of lesions were clearly outlined although on ultrasound images they were fuzzy. This allows to conclude that the use of the transducer designed offers an effective noninvasive tool not only to induce local necrotic lesions within treated tissue without damaging the surrounding tissue structures but also to test various chemotherapeutics activated by the HIFU beams in preclinical studies on small animals.

Keywords:
Spherical annular phased array transducer, Pulsed HIFU beam, Electronically adjustable focal length, Local tissue heating, Thermal ablation, Necrotic lesion

(30p.)
16.Nosewicz S., Rojek J., Chmielewski M., Pietrzak K., Lumelskyj D., Application of the Hertz formulation in the discrete element model of pressure-assisted sintering, GRANULAR MATTER, ISSN: 1434-5021, DOI: 10.1007/s10035-016-0699-9, Vol.19, No.1, pp.16-1-8, 2017
Nosewicz S., Rojek J., Chmielewski M., Pietrzak K., Lumelskyj D., Application of the Hertz formulation in the discrete element model of pressure-assisted sintering, GRANULAR MATTER, ISSN: 1434-5021, DOI: 10.1007/s10035-016-0699-9, Vol.19, No.1, pp.16-1-8, 2017

Abstract:
This paper presents the numerical modelling of initial powder compaction and pressure-assisted sintering performed by original viscoelastic discrete element model. The research is focused on the influence of the type of the model representing an elastic part of interparticle force. Two elastic contact models—linear and nonlinear Hertz model—have been implemented and used to analyse interaction of NiAl powder particles during compaction and sintering process. Numerical models have been validated using own experimental results. Microscopic effects (particle penetration) and macroscopic changes (relative density) have been compared. It has been shown that although both models represent properly macroscopic behaviour of the material at the sintering process, the Hertz model produces the results closer to the real experimental ones during the initial compaction stage. Evaluation of macroscopic quantities enables implementation of the discrete element model in the framework of the multiscale modelling framework which is currently developed for sintering processes.

Keywords:
Powder metallurgy, Sintering, Initial compaction, Elasticity, Discrete element method

(30p.)
17.Urbanek O., Sajkiewicz P., Pierini F., Czerkies M., Kołbuk D., Structure and properties of polycaprolactone/chitosan nonwovens tailored by solvent systems, Biomedical Materials, ISSN: 1748-6041, DOI: 10.1088/1748-605X/aa5647, Vol.12, No.1, pp.015020-1-12, 2017
Urbanek O., Sajkiewicz P., Pierini F., Czerkies M., Kołbuk D., Structure and properties of polycaprolactone/chitosan nonwovens tailored by solvent systems, Biomedical Materials, ISSN: 1748-6041, DOI: 10.1088/1748-605X/aa5647, Vol.12, No.1, pp.015020-1-12, 2017

Abstract:
Electrospinning of chitosan blends is a reasonable idea to prepare fibre mats for biomedical applications. Synthetic and natural components provide, for example, appropriate mechanical strength and biocompatibility, respectively. However, solvent characteristics and the polyelectrolyte nature of chitosan influence the spinnability of these blends. In order to compare the effect of solvent on polycaprolactone/chitosan fibres, two types of the most commonly used solvent systems were chosen, namely 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) and acetic acid (AA)/formic acid (FA). Results obtained by various experimental methods clearly indicated the effect of the solvent system on the structure and properties of electrospun polycaprolactone/chitosan fibres. Viscosity measurements confirmed different polymer–solvent interactions. Various molecular interactions resulting in different macromolecular conformations of chitosan influenced its spinnability and properties. HFIP enabled fibres to be obtained whose average diameter was less than 250 nm while maintaining the brittle and hydrophilic character of the nonwoven, typical for the chitosan component. Spectroscopy studies revealed the formation of chitosan salts in the case of the AA/FA solvent system. Chitosan salts visibly influenced the structure and properties of the prepared fibre mats. The use of AA/FA caused a reduction of Young's modulus and wettability of the proposed blends. It was confirmed that wettability, mechanical properties and the antibacterial effect of polycaprolactone/chitosan fibres may be tailored by selecting an appropriate solvent system. The MTT cell proliferation assay revealed an increase of cytotoxicity to mouse fibroblasts in the case of 25% w/w of chitosan in electrospun nonwovens.

Keywords:
chitosan, electrospinning, PCL/chitosan fibres, solvent system, chitosan salts

(30p.)
18.Meissner M., Acoustics of small rectangular rooms: Analytical and numerical determination of reverberation parameters, APPLIED ACOUSTICS, ISSN: 0003-682X, DOI: 10.1016/j.apacoust.2017.01.020, Vol.120, pp.111-119, 2017
Meissner M., Acoustics of small rectangular rooms: Analytical and numerical determination of reverberation parameters, APPLIED ACOUSTICS, ISSN: 0003-682X, DOI: 10.1016/j.apacoust.2017.01.020, Vol.120, pp.111-119, 2017

Abstract:
A small rectangular room with hard walls has a number of acoustic flaws and the most serious drawback is a long reverberation time. A technique commonly used for improving room acoustics consists in increasing a sound absorption on a ceiling. In this study, the impact of acoustical treatment of a ceiling on reverberant properties of a small rectangular room was examined. Changes in the modal reverberation time due to this treatment were investigated by the analytical method. As was evidenced by calculations, the initial increase in a sound absorption on a ceiling causes a substantial decrease in the modal reverberation time and a treatment efficiency decreases with a further absorption increase. It was found also that for a room with hard walls statistical and wave theories give the same result as the modal reverberation time for oblique modes and the Sabine’s reverberation time are identical. A more detailed information about reverberant properties of a room was provided by the numerical method employing a backward integration of the squared room impulse response. Using this method, global and local reverberation parameters were determined. Numerical simulations discovered a quite good agreement between global and local reverberation time and high differences between global and local early decay time resulting from a nonlinear shape of a decay curve. Therefore, one can conclude that the global decay times characterize reasonably well a reverberation process in a late stage of sound decay but they are not correctly describe this process in an initial stage.

Keywords:
Small room acoustics, Modal expansion method, Room impulse response, Reverberation time, Early decay time

(30p.)
19.Golasiński K.M., Pieczyska E.A., Staszczak M., Maj M., Furuta T., Kuramoto S., Infrared thermography applied for experimental investigation of thermomechanical couplings in Gum Metal, Quantitative InfraRed Thermography Journal, ISSN: 1768-6733, DOI: 10.1080/17686733.2017.1284295, pp.1-8, 2017
Golasiński K.M., Pieczyska E.A., Staszczak M., Maj M., Furuta T., Kuramoto S., Infrared thermography applied for experimental investigation of thermomechanical couplings in Gum Metal, Quantitative InfraRed Thermography Journal, ISSN: 1768-6733, DOI: 10.1080/17686733.2017.1284295, pp.1-8, 2017

Abstract:
Results of initial investigation of thermomechanical couplings in innovative β-Ti alloy called Gum Metal subjected to tension are presented. The experimental set-up, consisting of testing machine and infrared camera, enabled to obtain stress–strain curves with high accuracy and correlate them to estimated temperature changes of the specimen during the deformation process. Both ultra-low elastic modulus and high strength of Gum Metal were confirmed. The infrared measurements determined average and maximal temperature changes accompanying the alloy deformation process, allowed to estimate thermoelastic effect, which is related to the alloy yield point. The temperature distributions on the specimen surface served to analyse strain localization effects leading to the necking and rupture.

Keywords:
Gum Metal, thermomechanical coupling, nonlinear elasticity, yield point, infrared camera

(25p.)
20.Ignaczak J., Domański W., An asymptotic approach to one-dimensional model of nonlinear thermoelasticity at low temperatures and small strains, JOURNAL OF THERMAL STRESSES, ISSN: 0149-5739, DOI: 10.1080/01495739.2016.1276872, pp.1-10, 2017
Ignaczak J., Domański W., An asymptotic approach to one-dimensional model of nonlinear thermoelasticity at low temperatures and small strains, JOURNAL OF THERMAL STRESSES, ISSN: 0149-5739, DOI: 10.1080/01495739.2016.1276872, pp.1-10, 2017

Abstract:
A one-dimensional nonlinear homogeneous isotropic thermoelastic model with an elastic heat flow at low temperatures and small strains is analyzed using the method of weakly nonlinear asymptotics. For such a model, both the free energy and the heat flux vector depend not only on the absolute temperature and strain tensor but also on an elastic heat flow that satisfies an evolution equation. The governing equations are reduced to a matrix partial differential equations, and the associated Cauchy problem with a weakly perturbed initial condition is solved. The solution is given in the form of a power series with respect to a small parameter, the coefficients of which are functions of a slow variable that satisfy a system of nonlinear second-order ordinary differential transport equations. A family of closed-form solutions to the transport equations is obtained. For a particular Cauchy problem in which the initial data are generated by a closed-form solution to the transport equations, the asymptotic solution in the form of a sum of four traveling thermoelastic waves admitting blow-up amplitudes is presented.

Keywords:
Low temperatures, nonlinear thermoelasticity, small strains, weakly nonlinear asymptotics

(25p.)
21.Pamin J., Wcisło B., Kowalczyk-Gajewska K., Gradient-enhanced large strain thermoplasticity with automatic linearization and localization simulations, JOURNAL OF MECHANICS OF MATERIALS AND STRUCTURES, ISSN: 1559-3959, DOI: 10.2140/jomms.2017.12.123, Vol.12, No.1, pp.123-146, 2017
Pamin J., Wcisło B., Kowalczyk-Gajewska K., Gradient-enhanced large strain thermoplasticity with automatic linearization and localization simulations, JOURNAL OF MECHANICS OF MATERIALS AND STRUCTURES, ISSN: 1559-3959, DOI: 10.2140/jomms.2017.12.123, Vol.12, No.1, pp.123-146, 2017

Abstract:
The paper deals with the thermomechanical extension of a large strain hyperelasto-plasticity model and focuses on algorithmic aspects and localization simulations. The formulation includes the degradation of the yield strength due to the increase of an averaged plastic strain measure and temperature, thus, three sources for loss of stability are included in the description. A gradient-enhancement of the model is incorporated through an additional differential equation, but localization is also influenced by heat conduction. The finite element analysis is performed for an elongated plate in plane strain conditions, using different finite elements and values of material parameters related to regularization (internal length scales are related to gradient averaging as well as heat conduction). In particular, the influence of the F-bar enrichment on the simulation results is studied. All computational tests are performed using selfprogrammed user subroutines prepared within a symbolic-numerical tool AceGen which is equipped with automatic differentiation options, allowing for automatic linearization of the governing equations.

Keywords:
thermoplasticity, softening, gradient averaging, strain localization, automatic linearization, AceGen package

(20p.)
22.Nowak Z., Nowak M., Pęcherski R., Potoczek M., Śliwa R.E., Numerical Simulations of Mechanical Properties of Alumina Foams Based on Computed Tomography, JOURNAL OF MECHANICS OF MATERIALS AND STRUCTURES, ISSN: 1559-3959, DOI: 10.2140/jomms.2017.12.107, Vol.12, No.1, pp.107-121, 2017
Nowak Z., Nowak M., Pęcherski R., Potoczek M., Śliwa R.E., Numerical Simulations of Mechanical Properties of Alumina Foams Based on Computed Tomography, JOURNAL OF MECHANICS OF MATERIALS AND STRUCTURES, ISSN: 1559-3959, DOI: 10.2140/jomms.2017.12.107, Vol.12, No.1, pp.107-121, 2017

Abstract:
The aim of this paper is to apply the results of microtomography of alumina foam to create a numerical model and perform numerical simulations of compression tests. The geometric characteristics of real foam samples are estimated from tomographic and scanning electron microscopy images. The performance of the reconstructed models is compared to experimental values of elastic moduli. A preliminary analysis of failure strength simulations under compression of alumina foam is also provided.

Keywords:
Alumina open-cell foam, computed tomography microstructure, Young’s modulus, compressive strength of alumina foams

(20p.)
23.Błachowski B., An Y., Spencer Jr. B.F., Ou J., Axial strain accelerations approach for damage localization in statically determinate truss structures, Computer-Aided Civil and Infrastructure Engineering, ISSN: 1467-8667, DOI: 10.1111/mice.12258, pp.1-15, 2017
Błachowski B., An Y., Spencer Jr. B.F., Ou J., Axial strain accelerations approach for damage localization in statically determinate truss structures, Computer-Aided Civil and Infrastructure Engineering, ISSN: 1467-8667, DOI: 10.1111/mice.12258, pp.1-15, 2017

Abstract:
This work proposes an efficient and reliable method for damage localization in truss structures. The damage is localized on the basis of measured acceleration signals of the structure followed by simple statistical signal processing. It has three main advantages over many existing methods. Firstly, it can be directly applied to real engineering structures without the need of identifying modal parameters or solving any global optimization problem. Secondly, the proposed method has higher sensitivity to damage than some other frequently used methods and allows to localize damage as small as a few percents. Thirdly, it is a model-free method, which does not require precise finite element model development or updating. Validation of the method has been conducted on numerical examples and laboratory-scale trusses. Two types of frequently used trusses have been selected for this study, namely Howe and Bailey trusses. The presented experimental validation of the method shows its efficiency and robustness for damage localization in truss structures.

24.Konowrocki R., An Electricity Consumption of a Train Drive System Used in a High Speed Train Caused by Change of Mechanical Parameters of this Drive, III Konferencja Naukowa „Szkoła Logistyki” , 2017-01-10/01-13, Wisła (PL), pp.1-1, 2017
Konowrocki R., An Electricity Consumption of a Train Drive System Used in a High Speed Train Caused by Change of Mechanical Parameters of this Drive, III Konferencja Naukowa „Szkoła Logistyki” , 2017-01-10/01-13, Wisła (PL), pp.1-1, 2017

Abstract:
The cost of maintenance, the reliability and the safety of railway operation depend strongly on the quality of the wheelsets and driving systems. Deformations and mechanical vibrations are phenomena associated with a functioning of majority of railway vehicle drivetrain structures. The time dependent variation of the contact forces between the wheels and the rails is highest importance, as sources of a torsion vibration in the systems. The knowledge about torsional vibrations in drive transmission systems of railway vehicles is of a great importance in the fields dynamics and fatigue of the mechanical systems. An electromechanical model of the railway vehicle drive system has been presented in the work. The values of electrical parameter characterizing the driving motor obtained from electric motor model have been used for determine the amounts of electric energy consumed by self-excited torsional vibration in the wheelset drivetrain system.

Keywords:
electric motor, cost of maintenance, electromechanical model, torsion vibration

25.Konowrocki R., Kukulski J., Walczak S., Costs Operating of Railway Braking Systems Due to the Influence of Hot Spots on the Brake Discs, III Konferencja Naukowa „Szkoła Logistyki” , 2017-01-10/01-13, Wisła (PL), pp.1, 2017
Konowrocki R., Kukulski J., Walczak S., Costs Operating of Railway Braking Systems Due to the Influence of Hot Spots on the Brake Discs, III Konferencja Naukowa „Szkoła Logistyki” , 2017-01-10/01-13, Wisła (PL), pp.1, 2017

Abstract:
In the paper presents experimental studies the influence of the formation of the hot spots on a brake disc. The heat produced in the brake system often leads to the appearance of hot spots on the surfaces of friction pairs during rapid braking. Nature and extent of the intensity of the phenomenon depends greatly on the mechanical and thermal properties of these friction pair materials. The temperature distribution in the elements analyzed systems friction affects their thermal deformation, initiating the above phenomenon. Shown in the work of the results of tests and analyzes the formation of the hot bands and the hot spots on the brake discs used in high-speed railway vehicles, provided information on the temperature distribution on the surface.
One of the consequences of such a process is the increased wear and reduce the coefficient of friction. Measurements of the hardness of the hot bands and surface roughness of brake discs showed the effects of such phenomena on the change on the structure of the cast iron and steel discs materials. An increase the hardness of this hot area on the discs surface of may result in increased maintenance costs. The costs caused by for a more frequent lathing of the brake discs can occur. These changes also influences to reduce the coefficient of friction in the friction pair.

Keywords:
hotspot, maintenance costs, friction, infrared thermography, thermal coupling

26.Ustrzycka A., Kowalewski Z.L., Modelling of fatigue damage mechanisms supported by full-field optical methods, PLASTICITY 2017, INTERNATIONAL CONFERENCE ON PLASTICITY, DAMAGE, AND FRACTURE 2017, 2017-01-03/01-09, Puerto Vallarta (MX), pp.91-93, 2017
Ustrzycka A., Kowalewski Z.L., Modelling of fatigue damage mechanisms supported by full-field optical methods, PLASTICITY 2017, INTERNATIONAL CONFERENCE ON PLASTICITY, DAMAGE, AND FRACTURE 2017, 2017-01-03/01-09, Puerto Vallarta (MX), pp.91-93, 2017

Abstract:
The aim of this work consists a development of the Gurson-Tvergaard-Needleman model (GNT) of damage evolution in elastic-plastic materials. This model is supported by optical method of stress and strain monitoring (ESPI) for early detection, localization and monitoring of damage in materials under fatigue loading.

27.Labra C., Rojek J., Oñate E., Discrete/Finite Element Modelling of Rock Cutting with a TBM Disc Cutter, Rock Mechanics and Rock Engineering, ISSN: 0723-2632, DOI: 10.1007/s00603-016-1133-7, pp.1-18, 2016
Labra C., Rojek J., Oñate E., Discrete/Finite Element Modelling of Rock Cutting with a TBM Disc Cutter, Rock Mechanics and Rock Engineering, ISSN: 0723-2632, DOI: 10.1007/s00603-016-1133-7, pp.1-18, 2016

Abstract:
This paper presents advanced computer simulation of rock cutting process typical for excavation works in civil engineering. Theoretical formulation of the hybrid discrete/finite element model has been presented. The discrete and finite element methods have been used in different subdomains of a rock sample according to expected material behaviour, the part which is fractured and damaged during cutting is discretized with the discrete elements while the other part is treated as a continuous body and it is modelled using the finite element method. In this way, an optimum model is created, enabling a proper representation of the physical phenomena during cutting and efficient numerical computation. The model has been applied to simulation of the laboratory test of rock cutting with a single TBM (tunnel boring machine) disc cutter. The micromechanical parameters have been determined using the dimensionless relationships between micro- and macroscopic parameters. A number of numerical simulations of the LCM test in the unrelieved and relieved cutting modes have been performed. Numerical results have been compared with available data from in-situ measurements in a real TBM as well as with the theoretical predictions showing quite a good agreement. The numerical model has provided a new insight into the cutting mechanism enabling us to investigate the stress and pressure distribution at the tool–rock interaction. Sensitivity analysis of rock cutting performed for different parameters including disc geometry, cutting velocity, disc penetration and spacing has shown that the presented numerical model is a suitable tool for the design and optimization of rock cutting process.

Keywords:
Rock cutting, Disc cutters, TBM, Numerical model, Discrete/finite element method, Simulation

(40p.)
28.Pedrosa F.J., Rial J., Golasiński K.M., Guzik M.N., Quesada A., Fernández J.F., Deledda S., Camarero J., Bollero A., Towards high performance CoFe2O4 isotropic nanocrystalline powder for permanent magnet applications, APPLIED PHYSICS LETTERS, ISSN: 0003-6951, DOI: 10.1063/1.4969064, Vol.109, No.22, pp.223105-1-4, 2016
Pedrosa F.J., Rial J., Golasiński K.M., Guzik M.N., Quesada A., Fernández J.F., Deledda S., Camarero J., Bollero A., Towards high performance CoFe2O4 isotropic nanocrystalline powder for permanent magnet applications, APPLIED PHYSICS LETTERS, ISSN: 0003-6951, DOI: 10.1063/1.4969064, Vol.109, No.22, pp.223105-1-4, 2016

Abstract:
We report on a comparative study of high performance isotropic cobalt ferrite (CoFe2O4) powder processed by dry and surfactant assisted (wet) ball milling. Milling times as short as 1.5 min (dry) and 6 min (wet) have resulted in a 4-fold increase in coercivity, with a maximum achieved value above 318 kA/m (4 kOe). The use of surfactant is shown to be advantageous in the formation of a more homogeneous structure constituted by non-agglomerated and strained nanoparticles. A record (BH) max value of 18.6 kJ m −3 (2.34 MGOe) has been obtained for isotropic powder after post-processing annealing. This magnetic performance combined with the required short processing times and the unnecessary requirement of oxygen avoidance in the milling process, makes this CoFe2O4 powder a good candidate for permanent magnet applications.

Keywords:
Milling, Nanopowders, Powders, Coercive force, Surfactants

(40p.)
29.Kijewska M., Kocyk M., Kloss M., Stępniak K., Korwek Z., Polakowska R., Dąbrowski M., Gieryng A., Wojtas B., Ciechomska I.A., Kamińska B., The embryonic type of SPP1 transcriptional regulation is re-activated in glioblastoma, Oncotarget, ISSN: 1949-2553, DOI: 10.18632/oncotarget.14092, pp.1-16, 2016
Kijewska M., Kocyk M., Kloss M., Stępniak K., Korwek Z., Polakowska R., Dąbrowski M., Gieryng A., Wojtas B., Ciechomska I.A., Kamińska B., The embryonic type of SPP1 transcriptional regulation is re-activated in glioblastoma, Oncotarget, ISSN: 1949-2553, DOI: 10.18632/oncotarget.14092, pp.1-16, 2016

Abstract:
Osteopontin (SPP1, a secreted phosphoprotein 1) is primarily involved in immune responses, tissue remodelling and biomineralization. However, it is also overexpressed in many cancers and regulates tumour progression by increasing migration, invasion and cancer stem cell self-renewal. Mechanisms of SPP1 overexpression in gliomas are poorly understood. We demonstrate overexpression of two out of five SPP1 isoforms in glioblastoma (GBM) and differential isoform expression in glioma cell lines. Up-regulated SPP1 expression is associated with binding of the GLI1 transcription factor to the promoter and OCT4 (octamer-binding transcription factor 4) to the first SPP1 intron of the SPP1 gene in human glioma cells but not in non-transformed astrocytes. GLI1 knockdown reduced SPP1 mRNA and protein levels in glioma cells. GLI1 and OCT4 are known regulators of stem cell pluripotency. GBMs contain rare cells that express stem cell markers and display ability to self-renew. We reveal that SPP1 is overexpressed in glioma initiating cells defined by high rhodamine 123 efflux, sphere forming capacity and stemness marker expression. Forced differentiation of human glioma spheres reduced SPP1 expression. Knockdown of SPP1, GLI1 or CD44 with siRNAs diminished sphere formation. C6 glioma cells stably depleted of Spp1 displayed reduced sphere forming capacity and downregulated stemness marker expression. Overexpression of the wild type Spp1, but not Spp1 lacking a Cd44 binding domain, rescued cell ability to form spheres. Our findings show re-activation of the embryonic-type transcriptional regulation of SPP1 in malignant gliomas and point to the importance of SPP1-CD44 interactions in self-renewal and pluripotency glioma initiating cells.

Keywords:
osteopontin, glioma initiating cells, transcription factors, stemness factors, self-renewal

(40p.)
30.Giusti S.M., Mróz Z., Novotny A.A., Sokołowski J., Topology design of thermomechanical actuators, STRUCTURAL AND MULTIDISCIPLINARY OPTIMIZATION, ISSN: 1615-147X, DOI: 10.1007/s00158-016-1593-0, pp.1-13, 2016
Giusti S.M., Mróz Z., Novotny A.A., Sokołowski J., Topology design of thermomechanical actuators, STRUCTURAL AND MULTIDISCIPLINARY OPTIMIZATION, ISSN: 1615-147X, DOI: 10.1007/s00158-016-1593-0, pp.1-13, 2016

Abstract:
The paper deals with topology design of thermomechanical actuators. The goal of shape optimization is to maximize the output displacement in a given direction on the boundary of the elastic body, which is submitted to a thermal excitation that induces a dilatation/contraction of the thermomechanical device. The optimal structure is identified by an elastic material distribution, while a very compliant (weak) material is used to mimic voids. The mathematical model of an actuator takes the form of a semicoupled system of partial differential equations. The boundary value problem includes two components, the Navier equation for linear elasticity coupled with the Poisson equation for steady-state heat conduction. The mechanical coupling is the thermal stress induced by the temperature field. Given the integral shape functional, we evaluate its topological derivative with respect to the nucleation of a small circular inclusion with the thermomechanical properties governed by two contrast parameters. The obtained topological derivative is employed to generate a steepest descent direction within the level set numerical procedure of topology optimization in a fixed geometrical domain. Finally, several finite element-based examples for the topology design of thermomechanical actuators are presented.

Keywords:
Shape-topology optimization, Topological derivative, Thermomechanical devices, Optimum design

(35p.)
31.Chmielewski M., Pietrzak K., Teodorczyk M., Nosewicz S., Jarząbek D., Zybała R., Bazarnik P., Lewandowska M., Strojny-Nędza A., Effect of metallic coating on the properties of copper-silicon carbide composites, APPLIED SURFACE SCIENCE, ISSN: 0169-4332, DOI: 10.1016/j.apsusc.2016.12.130, pp.1-37, 2016
Chmielewski M., Pietrzak K., Teodorczyk M., Nosewicz S., Jarząbek D., Zybała R., Bazarnik P., Lewandowska M., Strojny-Nędza A., Effect of metallic coating on the properties of copper-silicon carbide composites, APPLIED SURFACE SCIENCE, ISSN: 0169-4332, DOI: 10.1016/j.apsusc.2016.12.130, pp.1-37, 2016

Abstract:
In the presented paper a coating of SiC particles with a metallic layer were used to prepare copper matrix composite materials. The role of the layer was to protect the silicon carbide from decomposition and dissolution of silicon in the copper matrix during the sintering process. The SiC particles were covered by chromium, tungsten and titanium using Plasma Vapour Deposition method. After powder mixing of components, the final densification process via Spark Plasma Sintering (SPS) method at temperature 950C was provided. The almost fully dense materials were obtained (> 97.5%). The microstructure of obtained composites was studied using scanning electron microscopy as well as transmission electron microscopy. The microstructural analysis of composites confirmed that regardless of the type of deposited material, there is no evidence for decomposition process of silicon carbide in copper. In order to measure the strength of the interface between ceramic particles and the metal matrix, the micro tensile tests have been performed. Furthermore, thermal diffusivity was measured with the use of the laser pulse technique. In the context of performed studies, the tungsten coating seems to be the most promising solution for heat sink application. Compared to pure composites without metallic layer, Cu-SiC with W coating indicate the higher tensile strength and thermal diffusitivy, irrespective of an amount of SiC reinforcement. The improvement of the composite properties is related to advantageous condition of Cu-SiC interface characterized by well homogenity and low porosity, as well as individual properties of the tungsten coating material.

Keywords:
metal matrix composites, silicon carbide, metallic layers deposition, thermal conductovity, interface strength

(35p.)
32.Winnicki M., Małachowska A., Baszczuk A., Rutkowska-Gorczyca M., Kukla D., Lachowicz M., Ambroziak A., Corrosion protection and electrical conductivity of copper coatings deposited by low-pressure cold spraying, SURFACE AND COATINGS TECHNOLOGY, ISSN: 0257-8972, DOI: 10.1016/j.surfcoat.2016.12.101, pp.1-19, 2016
Winnicki M., Małachowska A., Baszczuk A., Rutkowska-Gorczyca M., Kukla D., Lachowicz M., Ambroziak A., Corrosion protection and electrical conductivity of copper coatings deposited by low-pressure cold spraying, SURFACE AND COATINGS TECHNOLOGY, ISSN: 0257-8972, DOI: 10.1016/j.surfcoat.2016.12.101, pp.1-19, 2016

Abstract:
Aluminium/copper contacts occur in power networks made of aluminium alloy busbars. Bolted joints of aluminium and copper cause galvanic corrosion of aluminium in the presence of electrolyte. The paper focuses on the effect of different powder morphology and the addition of ceramics on coating porosity and consequently on corrosion resistance and electrical conductivity behaviour. In this work, corrosion protection of copper coatings deposited by low-pressure cold spraying (LPCS) onto AA 1350 aluminium alloy is examined. The coatings were sprayed using two copper powders of different morphology, namely spherical and dendritic ones. These powders were mixed with alumina before spraying in a 50:50 weight ratio and composite coatings were deposited. The coating microstructures were characterized by the scanning electron microscopy (SEM). The measurements of coating hardness in the middle of the coating thickness were carried out. The coating corrosion protection was analysed by polarization measurements. All coatings showed increased corrosion potential as compared to the substrate. The electrical conductivity of coatings was determined by eddy-current measurements and showed coating conductivity up to 63% IACS. Moreover, coatings heat treatment was conducted to further increase electrical conductivity.

Keywords:
cold spray, corrosion resistance, polarization measurements, electrical conductivity

(35p.)
33.Basista M., Węglewski W., Bochenek K., Poniżnik Z., Nowak Z., Micro-CT Finite Element Analysis of Thermal Residual Stresses and Fracture in Metal-Ceramic Composites, Advanced Engineering Materials, ISSN: 1438-1656, DOI: 10.1002/adem.201600725, pp.1-9, 2016
Basista M., Węglewski W., Bochenek K., Poniżnik Z., Nowak Z., Micro-CT Finite Element Analysis of Thermal Residual Stresses and Fracture in Metal-Ceramic Composites, Advanced Engineering Materials, ISSN: 1438-1656, DOI: 10.1002/adem.201600725, pp.1-9, 2016

Abstract:
This paper presents a simple way of using X-ray micro-computed tomography (micro-CT) in numerical modeling of material properties of metal-ceramic composites. It shows step by step the proposed methodology with details of the finite element mesh creation, so that it can easily be reproduced by interested researchers. Two case studies are considered to show the proposed approach at work: i) determination of processing-induced residual stresses in hot pressed Cr/Al2O3 and NiAl/Al2O3 particulate composites and ii) determination of J-integral for an interpenetrating phase composite made of porous alumina preform infiltrated with molten copper. The method is straightforward and effective but has its limitations that are pointed out.

(25p.)
34.Petryk H., Stupkiewicz S., A minimal gradient-enhancement of the classical continuum theory of crystal plasticity. Part I: The hardening law, ARCHIVES OF MECHANICS, ISSN: 0373-2029, Vol.68, No.6, pp.459-485, 2016
Petryk H., Stupkiewicz S., A minimal gradient-enhancement of the classical continuum theory of crystal plasticity. Part I: The hardening law, ARCHIVES OF MECHANICS, ISSN: 0373-2029, Vol.68, No.6, pp.459-485, 2016

Abstract:
A simple gradient-enhancement of the classical continuum theory of plasticity of single crystals deformed by multislip is proposed for incorporating size effects in a manner consistent with phenomenological laws established in materials science. Despite considerable efforts in developing gradient theories, there is no consensus regarding the minimal set of physically based assumptions needed to capture the slip-gradient effects in metal single crystals and to provide a benchmark for more refined approaches. In order to make a step towards such a reference model, the concept of the tensorial density of geometrically necessary dislocations generated by slip-rate gradients is combined with a generalized form of the classical Taylor formula for the flow stress. In the governing equations in the rate form, the derived internal length scale is expressed through the current flow stress and standard parameters so that no further assumption is needed to define a characteristic length. It is shown that this internal length scale is directly related to the mean free path of dislocations and possesses physical interpretation which is frequently missing in other gradient-plasticity models.

Keywords:
gradient plasticity, geometrically necessary dislocations, single crystal, strain-hardening, internal length scale, size effect

(20p.)
35.Stupkiewicz S., Petryk H., A minimal gradient-enhancement of the classical continuum theory of crystal plasticity. Part II: Size effects, ARCHIVES OF MECHANICS, ISSN: 0373-2029, Vol.68, No.6, pp.487-513, 2016
Stupkiewicz S., Petryk H., A minimal gradient-enhancement of the classical continuum theory of crystal plasticity. Part II: Size effects, ARCHIVES OF MECHANICS, ISSN: 0373-2029, Vol.68, No.6, pp.487-513, 2016

Abstract:
In our previous paper, a simple gradient-enhancement of the classical continuum theory of plasticity of single crystals deformed by multislip has been proposed for incorporating size effects. A single internal length scale has been derived as an explicit function of the flow stress defined as the isotropic part of critical resolved shear stresses. The present work is focused on verification whether the simplifications involved are not too severe and allow satisfactory predictions of size effects. The model has been implemented in a finite element code and applied to three-dimensional simulations of fcc single crystals. We have found that the experimentally observed indentation size effect in a Cu single crystal is captured correctly in spite of the absence of any adjustable length-scale parameter. The finite element treatment relies on introducing non-local slip rates that average and smoothen on an element scale the corresponding local quantities. Convergence of the finite element solution to the analytical one is also verified for the one-dimensional problem of a boundary layer formed at a constrained interface.

Keywords:
gradient plasticity, geometrically necessary dislocations, boundary layer, size effects, indentation, finite element method

(20p.)
36.Sulejczak D., Taraszewska A., Chrapusta S.J., Dziewulska D., Nakielski P., Rafałowska J., Nanofiber mat spinal cord dressing-released glutamate impairs blood-spinal cord barrier, FOLIA NEUROPATHOLOGICA, ISSN: 1641-4640, DOI: 10.5114/fn.2016.64818, Vol.54, No.4, pp.392-404, 2016
Sulejczak D., Taraszewska A., Chrapusta S.J., Dziewulska D., Nakielski P., Rafałowska J., Nanofiber mat spinal cord dressing-released glutamate impairs blood-spinal cord barrier, FOLIA NEUROPATHOLOGICA, ISSN: 1641-4640, DOI: 10.5114/fn.2016.64818, Vol.54, No.4, pp.392-404, 2016

Abstract:
An excessive glutamate level can result in excitotoxic damage and death of central nervous system (CNS) cells, and is involved in the pathogenesis of many CNS diseases. It may also be related to a failure of the blood-spinal cord barrier (BSCB). This study was aimed at examining the effects of extended administration of monosodium glutamate on the BSCB and spinal cord cells in adult male Wistar rats. The glutamate was delivered by subarachnoidal application of glutamate-carrying electrospun nanofiber mat dressing at the lumbar enlargement level. Half of the rats with the glutamate-loaded mat application were treated systemically with the histone deacetylase inhibitor valproic acid. A group of intact rats and a rat group with subarachnoidal application of an ‘empty’ (i.e., carrying no glutamate) nanofiber mat dressing served as controls. All the rats were euthanized three weeks later and lumbar fragments of their spinal cords were harvested for histological, immunohistochemical and ultrastructural studies. The samples from controls revealed normal parenchyma and BSCB morphology, whereas those from rats with the glutamate-loaded nanofiber mat dressing showed many intraparenchymal microhemorrhages of variable sizes. The capillaries in the vicinity of the glutamate-carrying dressing (in the meninges and white matter alike) were edematous and leaky, and their endothelial cells showed degenerative changes: extensive swelling, enhanced vacuo­lization and the presence of vascular intraluminal projections. However, endothelial tight junctions were generally well preserved. Some endothelial cells were dying by necrosis or apoptosis. The adjacent parenchyma showed astrogliosis with astrocytic hypertrophy and swelling of perivascular astrocytic feet. Neurons in the parenchyma revealed multiple symptoms of degeneration, including, inter alia, perikaryal, dendritic and axonal swelling, and destruction of organelles. All the damage symptoms were slightly less severe in the rats given valproic acid treatment, and were absent from both the intact rats and the rats with ‘empty’ nanofiber mat dressing. These results demonstrate that glutamate-loaded nanofiber mat dressing can locally create glutamate levels capable of damaging BSCB and that the resulting damage can be mitigated with concurrent systemic valproate treatment.

Keywords:
astrocyte, blood-spinal cord barrier, CNS damage, degeneration, endothelium, excitotoxicity, glutamate, neuron, valproate, vessels

(20p.)
37.Postek E., Sadowski T., Cracks in Interfaces and Around Their Junctions in WC/Co Composite, ENGINEERING TRANSACTIONS (ROZPRAWY INŻYNIERSKIE), ISSN: 0867-888X, Vol.64, No.4, pp.589-596, 2016
Postek E., Sadowski T., Cracks in Interfaces and Around Their Junctions in WC/Co Composite, ENGINEERING TRANSACTIONS (ROZPRAWY INŻYNIERSKIE), ISSN: 0867-888X, Vol.64, No.4, pp.589-596, 2016

Abstract:
WC/Co ceramic metal-matrix composites are characterized by very high mechanical properties that allow for application of the composites mostly in production of different types of cutting tools. By combining in a composite structure a phase of brittle hard wolfram carbide (WC) grains with a metallic interface of cobalt (Co) that exhibits plastic properties, a geometrically complex microstructure with significantly different mechanical properties of the combined phases is created, see Fig. 1a. The presence of the elastic-plastic interface material, i.e. Co binder, in the composite structure is the reason for initiation of technological defects – mainly material porosity. During material loading pores start to coalesce and finally one can observe creation of microcracks system distributed along interfaces. The aim of the paper is to show the previously formulated model [1, 2] of the polycrystalline composite to be extended towards cracks development around the junctions of the interfaces. The obtained numerical results indicate that in the junctions high stress concentrations were observed, which leads to crack initiation and its further unstable propagation, and finally the composite failure. Results indicate that the first crack appears close to the junction and that the load carrying capacity of the sample is overestimated if a crack model in the interfaces is not assumed.

Keywords:
metal-ceramic composite, interface elements, crack propagation at composite junctions

(15p.)
38.Świątek Z., Gradys A., Maj Ł., Morgiel J., Marszałek K.W., Mania R., Szlezynger M., XRD and TEM in situ Heating of Large Period Ni/Al Multilayer Coatings, ACTA PHYSICA POLONICA A, ISSN: 0587-4246, DOI: 10.12693/APhysPolA.130.880, Vol.130, No.4, pp.880-883, 2016
Świątek Z., Gradys A., Maj Ł., Morgiel J., Marszałek K.W., Mania R., Szlezynger M., XRD and TEM in situ Heating of Large Period Ni/Al Multilayer Coatings, ACTA PHYSICA POLONICA A, ISSN: 0587-4246, DOI: 10.12693/APhysPolA.130.880, Vol.130, No.4, pp.880-883, 2016

Abstract:
The Ni/Al multilayer coating of λ ≈100 nm was deposited onto (001)-oriented monocrystalline silicon substrate using double target magnetron sputtering system equipped with rotating sample holder. The thicknesses of alternating layers were adjusted in the way to preserve the chemical composition ratio close to 50%Al:50%Ni (at.%). The in situ X-ray diffraction and in situ transmission electron microscopy heating experiments were carried out at relatively low heating rates (20°C/min) in order to study the phase transformation sequence. The investigations revealed that the reaction between Ni and Al multilayers starts at ≈200°C with precipitation of Al₃Ni phase, while above 300°C dominates precipitation of Ni₃Al and NiAl intermetallic phases. Both the X-ray and electron diffractions acquired at 450°C confirmed presence of the Ni₃Al and NiAl intermetallics, but the former pointed at still lasting traces of Ni(Al) solid solution.

Keywords:
transmission electron microscopy, multilayers

(15p.)
39.Gambin B., Byra M., Kruglenko E., Doubrovina O., Nowicki A., Ultrasonic Measurement of Temperature Rise in Breast Cyst and in Neighbouring Tissues as a Method of Tissue Differentiation, ARCHIVES OF ACOUSTICS, ISSN: 0137-5075, DOI: 10.1515/aoa-2016-0076, Vol.41, No.4, pp.791-798, 2016
Gambin B., Byra M., Kruglenko E., Doubrovina O., Nowicki A., Ultrasonic Measurement of Temperature Rise in Breast Cyst and in Neighbouring Tissues as a Method of Tissue Differentiation, ARCHIVES OF ACOUSTICS, ISSN: 0137-5075, DOI: 10.1515/aoa-2016-0076, Vol.41, No.4, pp.791-798, 2016

Abstract:
Texture of ultrasound images contain information about the properties of examined tissues. The analysis of statistical properties of backscattered ultrasonic echoes has been recently successfully applied to differentiate healthy breast tissue from the benign and malignant lesions. We propose a novel procedure of tissue characterization based on acquiring backscattered echoes from the heated breast. We have proved that the temperature increase inside the breast modifies the intensity, spectrum of the backscattered signals and the probability density function of envelope samples. We discuss the differences in probability density functions in two types of tissue regions, e.g. cysts and the surrounding glandular tissue regions. Independently, Pennes bioheat equation in heterogeneous breast tissue was used to describe the heating process. We applied the finite element method to solve this equation. Results have been compared with the ultrasonic predictions of the temperature distribution. The results confirm the possibility of distinguishing the differences in thermal and acoustical properties of breast cyst and surrounding glandular tissues.

Keywords:
medical ultrasound, temperature changes in vivo, breast tissue, ultrasonic temperature measurement

(15p.)
40.Bojar W., Kucharska M., Ciach T., Paśnik I., Korobowicz E., Patkowski K., Gruszecki T., Szymanowski M., Rzodkiewicz P., In vivo performance of the experimental chitosan based bone substitute - advanced therapy medicinal product. A study in sheep, Acta Poloniae Pharmaceutica - Drug Research, ISSN: 0001-6837, Vol.73, No.1, pp.209-217, 2016
Bojar W., Kucharska M., Ciach T., Paśnik I., Korobowicz E., Patkowski K., Gruszecki T., Szymanowski M., Rzodkiewicz P., In vivo performance of the experimental chitosan based bone substitute - advanced therapy medicinal product. A study in sheep, Acta Poloniae Pharmaceutica - Drug Research, ISSN: 0001-6837, Vol.73, No.1, pp.209-217, 2016

Abstract:
When evaluating a novel bone substitute material, advanced in vivo testing is an important step in development and safety affirmation. Sheep seems to be a valuable model for human one turnover and remodeling activity. The experimental material composed with the stem cells is an advanced therapy medicinal product (acc. to EC Regulation 1394/2007). Our research focuses on histological differences in bone formation (guided bone regeneration n GBR) in sheep maxillas after implantation of the new chitosan / tricalcium phosphate / alginate (CH/TCP/Alg) biomaterial in comparison to the commercially available xenogenic bone graft and a/m enhanced with the stem cells isolated from the adipose tissue. Twelve adult female sheep of BCP synthetic line, weighing 60-70 kg were used for the study. The 11 mm diameter defects in maxilla bone were prepared with a trephine bur under general anesthesia and then filled with the bone substitute materials: CH/TCP/Alg, BioOss Collagen, Geistlich AG (BO), CH/TCP/Alg composed with the stem cells (CH/S) or left just with the blood clot (BC). Inbreeding cycle of the animals terminated at 4 months after surgery. Dissected specimens of the maxilla were evaluated histologically and preliminary under microtomography. Histological evaluation showed early new bone formation observed around the experimental biomaterial and commercially available BO. There were no features of purulent inflammation and necrosis, or granulomatous inflammation. Microscopic examination after 4 months following the surgery revealed trabecular bone formation around chitosan based bone graft and xenogenic material with no significant inflammatory response. Different results – no bone recreation were observed for the negative control (BC). In conclusion, the tested materials (CH/TCP/Alg and BO) showed a high degree of biocompatibility and some osteoconductivity in comparison with the control group. Although the handiness, granules size and setting time of CH/TCP/Alg may be refined for future clinical tests. The relevant beneficial influence of using the adipose derived stem cells in GBR was not confirmed in this model.

Keywords:
alginate, bone substitute material, chitosan, guided bone regeneration, β-tricalcium phosphate, sheep model, stem cells

(15p.)
41.Lewandowski M., Walczak M., Karwat P., Witek B., Karłowicz P., Research and Medical Transcranial Doppler System, ARCHIVES OF ACOUSTICS, ISSN: 0137-5075, DOI: 10.1515/aoa-2016-0074, Vol.41, No.4, pp.773-781, 2016
Lewandowski M., Walczak M., Karwat P., Witek B., Karłowicz P., Research and Medical Transcranial Doppler System, ARCHIVES OF ACOUSTICS, ISSN: 0137-5075, DOI: 10.1515/aoa-2016-0074, Vol.41, No.4, pp.773-781, 2016

Abstract:
A new ultrasound digital transcranial Doppler system (digiTDS) is introduced. The digiTDS enables diagnosis of intracranial vessels which are rather difficult to penetrate for standard systems. The device can display a color map of flow velocities (in time-depth domain) and a spectrogram of a Doppler signal obtained at particular depth. The system offers a multigate processing which allows to display a number of spectrograms simultaneously and to reconstruct a flow velocity profile.
The digital signal processing in digiTDS is partitioned between hardware and software parts. The hardware part (based on FPGA) executes a signal demodulation and reduces data stream. The software part (PC) performs the Doppler processing and display tasks. The hardware-software partitioning allowed to build a flexible Doppler platform at a relatively low cost.
The digiTDS design fulfills all necessary medical standards being a new useful tool in the transcranial field as well as in heart velocimetry research.

Keywords:
Doppler system, digital signal processing, hardware-software partitioning, field programmable gate arrays

(15p.)
42.Kúdela Jr. S., Švec P., Bajana O., Orovčík L., Ranachowski P., Ranachowski Z., Strengthening in dual-phase structured Mg-Li-Zn alloys, KOVOVE MATERIALY-METALLIC MATERIALS, ISSN: 0023-432X, DOI: 10.4149/km_2016_6_483, Vol.54, pp.483-489, 2016
Kúdela Jr. S., Švec P., Bajana O., Orovčík L., Ranachowski P., Ranachowski Z., Strengthening in dual-phase structured Mg-Li-Zn alloys, KOVOVE MATERIALY-METALLIC MATERIALS, ISSN: 0023-432X, DOI: 10.4149/km_2016_6_483, Vol.54, pp.483-489, 2016

Abstract:
Proof stress Rp0.2 of dual-phase α + β structured Mg-Li and Mg-Li-Zn alloys has been inspected in terms of the strengthening contributions of α- and β-phases. The alloys studied with a variable fraction of α- and β-phases have been subjected to compression straining tests, microhardness measurements and structural analysis by EDX and XRD. Alloying with 1.5 wt.% Zn results in the hardening of both α- and β-phases which however exhibit different hardening responses due to different Zn enrichment. The rule of the mixture has been used to interpret Rp0.2 values by taking into account the fraction of α- and β-phases and their strength level represented by their microhardness. Compression stress-strain curves indicate that work hardening of alloys studied depends considerably on the fraction of α-phase and is higher for Zn-containing alloys.

Keywords:
Mg-Li, Mg-Li-Zn, dual-phase alloy, solution hardening, ageing, work hardening

(15p.)
43.Wasilewski M., Pisarski D., Bajer C.I., Adaptive stabilization of partially damaged vibrating structures, Machine Dynamics Research, ISSN: 2080-9948, Vol.40, No.1, pp.65-82, 2016
Wasilewski M., Pisarski D., Bajer C.I., Adaptive stabilization of partially damaged vibrating structures, Machine Dynamics Research, ISSN: 2080-9948, Vol.40, No.1, pp.65-82, 2016

Abstract:
In this paper, an online adaptive continuous-time control algorithm will be studied in the vibration control problem. The examined algorithm is a Reinforcement Learning based scheme able to adapt to the changing system’s dynamics and providing control converging to the optimal control. Firstly, a brief description of the algorithm is provided. Then, the algorithm is studied by the numeric simulation. The controlled model is a simple conjugate oscillator with a sudden change of its rigidity. The effectiveness of the adaptation of the algorithm is compared to the simulation results of controlling the same object by the traditional Linear Quadratic Regulator. Because of the lack of constraints for a system size or its linearity, this algorithm is suitable for optimal stabilization of more complex vibrating structures.

Keywords:
Vibration control, Adaptive control, Optimal control, Policy iterations, Hamilton-Jacobi-Bellman equation

(14p.)
44.Widłaszewski J., Dwukierunkowe mikrogięcie laserowe dla układów MOEMS, MECHANIK, ISSN: 0025-6552, DOI: 10.17814/mechanik.2016.12.572, Vol.89, No.12, pp.1824-1830, 2016
Widłaszewski J., Dwukierunkowe mikrogięcie laserowe dla układów MOEMS, MECHANIK, ISSN: 0025-6552, DOI: 10.17814/mechanik.2016.12.572, Vol.89, No.12, pp.1824-1830, 2016

Abstract:
Bezdotykowa laserowa metoda mikropozycjonowania pozwala omijać ograniczenia tradycyjnych technik mechanicznych stosowanych przy montażu mikroukładów elektromechanicznych (micro-electro-mechanical systems, MEMS) oraz optoelektromechanicznych (micro-opto-electro-mechanical systems, MOEMS). Przedstawiono badania doświadczalne i symulacje numeryczne mechanizmu termicznego mikrogięcia, który pozwala uzyskiwać deformacje dwukierunkowe, to jest w kierunku do lub od padającej wiązki laserowej, w zależności od przyjętych parametrów obróbki. Zweryfikowany doświadczalnie model numeryczny umożliwił wyjaśnienie zachowania małych belek wysięgnikowych wykonanych ze stali nierdzewnej, poddawanych nagrzewaniu impulsem lasera Nd:YAG. Przy ustalonej długości impulsu kierunek gięcia zależy od mocy wiązki laserowej. Ujawniony mechanizm gięcia charakteryzuje się występowaniem znacznego dodatniego plastycznego odkształcenia wzdłużnego w obszarach brzegowych nagrzewanej belki. Deformacja wynika z dużego gradientu temperatury na szerokości belki, z pewnym udziałem gradientu na kierunku grubości. Zastosowanie tego mechanizmu otwiera nowe możliwości przed laserową technologią mikropozycjonowania, zwłaszcza gdy obrabiany element jest dostępny tylko z jednej strony.

Keywords:
kształtowanie laserowe, gięcie laserowe, laserowe mikropozycjonowanie, mikroukłady optoelektromechaniczne

(11p.)
45.Radziejewska J., Stan warstwy wierzchniej po laserowej oraz laserowo-mechanicznej modyfikacji powierzchni, PRZEGLĄD SPAWALNICTWA, ISSN: 0033-2364, Vol.88, No.3, pp.9-13, 2016
Radziejewska J., Stan warstwy wierzchniej po laserowej oraz laserowo-mechanicznej modyfikacji powierzchni, PRZEGLĄD SPAWALNICTWA, ISSN: 0033-2364, Vol.88, No.3, pp.9-13, 2016

Abstract:
W pracy przedstawiono analizę stanu warstwy wierzchniej po laserowym stopowaniu stali Stellitem 6 oraz obróbce hybrydowej łączącej laserowe stopowaniem z obróbką nagniataniem. Obróbka hybrydowa prowadzona była na stanowisku laserowym. Do realizacji procesu nagniatania powierzchni wykorzystano głowicę do nagniatania ślizgowego umożliwiającą obróbkę w podwyższonych temperaturach jak i na zimno. Ocenę efektów obróbki hybrydowej przeprowadzono na podstawie badań chropowatości, mikrostruktury, mikrotwardości oraz badań naprężeń własnych.

Keywords:
stopowanie laserowe, nagniatanie, obróbka hybrydowa

(9p.)
46.Gambin B., Kruglenko E., Byra M., Relationships between Acoustical Properties and Stiffness of Soft Tissue Phantoms, HYDROACOUSTICS, ISSN: 1642-1817, Vol.19, pp.111-120, 2016
Gambin B., Kruglenko E., Byra M., Relationships between Acoustical Properties and Stiffness of Soft Tissue Phantoms, HYDROACOUSTICS, ISSN: 1642-1817, Vol.19, pp.111-120, 2016

Abstract:
Polyvinyl-alcohol cryogel is commonly used for soft tissue phantom manufacture. The gel formation from an aqueous solution of polyvinyl-alcohol takes place during the freezing and thawing cycle. The aim of this work was to assess the degree of gel solidification, hence the material stiffness, by means of quantitative ultrasound. We manufactured three phantoms which differed in the number of freezing/thawing cycles. First, tissue phantoms were examined with an elastography technique. Next, we measured the speed of sound and the attenuation coefficient. What is more, the inter structure variations in phantoms were assessed with the Nakagami imaging which quantifies the scattering properties of the backscattered ultrasound echo. Obtained results confirmed the connection between the number of freezing/thawing cycles and the solidification process. We defined the boundary layer as a region which has a different structure than the sample interior. Next, for each phantom this layer was extracted based on a Nakagami parameter map. We calculated that the thickness of the boundary layer was lower in samples which were subjected to a larger number of freezing/thawing cycles.

Keywords:
soft tissue phantoms, elastography, ultrasound attenuation, speed of sound, Nakagami maps, stiffness

(6p.)
47.Gambin B., Wójcik J., Doubrovina O., Differentiation of random structure properties using wavelet analysis of backscattered ultrasound, HYDROACOUSTICS, ISSN: 1642-1817, Vol.19, pp.121-128, 2016
Gambin B., Wójcik J., Doubrovina O., Differentiation of random structure properties using wavelet analysis of backscattered ultrasound, HYDROACOUSTICS, ISSN: 1642-1817, Vol.19, pp.121-128, 2016

Abstract:
The aim of this work was to find the differences between random media by analyzing the properties of the ultrasound signals backscattered from the inhomogeneities. A numerical model is used to generate two types of random media. The first has the randomness in scatterers’ positions and the second has the randomness in the size and acoustical properties of scatterers. The numerical model of wave scattering has been used to simulate the RF (radio frequency) signals caused by the incident pulse traveling as a plane wave. The markers of randomness type differences between the scattering media were obtained with the help of the spectral and wavelet analysis. The effect of differences in randomness type is more spectacular when the wavelet analysis is performed.

Keywords:
spectrogram, scalogram, wavelets, random scattering structure

(6p.)
48.Karwat P., Kujawska T., Secomski W., Gambin B., Litniewski J., Application of ultrasound to noninvasive imaging of temperature distribution induced in tissue, HYDROACOUSTICS, ISSN: 1642-1817, Vol.19, pp.219-228, 2016
Karwat P., Kujawska T., Secomski W., Gambin B., Litniewski J., Application of ultrasound to noninvasive imaging of temperature distribution induced in tissue, HYDROACOUSTICS, ISSN: 1642-1817, Vol.19, pp.219-228, 2016

Abstract:
Therapeutic and surgical applications of High Intensity Focused Ultrasound (HIFU) require monitoring of local temperature rises induced inside tissues. It is needed to appropriately target the focal plane, and hence the whole focal volume inside the tumor tissue, prior to thermo-ablative treatment, and the beginning of tissue necrosis. In this study we present an ultrasound method, which calculates the variations of the speed of sound in the locally heated tissue. Changes in velocity correspond to temperature change. The method calculates a 2D distribution of changes in the sound velocity, by estimation of the local phase shifts of RF echo-signals backscattered from the heated tissue volume (the focal volume of the HIFU beam), and received by an ultrasound scanner (23). The technique enabled temperature imaging of the heated tissue volume from the very inception of heating. The results indicated that the contrast sensitivity for imaging of relative changes in the sound speed was on the order of 0.06%; corresponding to an increase in the tissue temperature by about 2 °C.

Keywords:
HIFU, echo phase shift, parametric imaging, velocity/brightness CNR

(6p.)
49.Nowicki A., Secomski W., Trawiński Z., Lewandowski M., Trots I., Szubielski M., Olszewski R., Estimation of radial artery reactive response using high frequency ultrasound, HYDROACOUSTICS, ISSN: 1642-1817, Vol.19, pp.297-306, 2016
Nowicki A., Secomski W., Trawiński Z., Lewandowski M., Trots I., Szubielski M., Olszewski R., Estimation of radial artery reactive response using high frequency ultrasound, HYDROACOUSTICS, ISSN: 1642-1817, Vol.19, pp.297-306, 2016

Abstract:
Background:
There is a growing interest in the application of non-invasive clinical tools allowing one to assess the endothelial function, preceding atherosclerosis. The precision in estimating of the artery Flow Mediated Vasodilation (FMD) using standard 10-12 MHz linear array probes does not exceed 0.2 mm, far beyond that required.

Methods:
We have introduced a wide-band, high frequency 25-30 MHz, Golay encoded wobbling type imaging to measure dilation of the radial artery instead of the brachial one. 18 young volunteers, and 4 volunteers with cardiac events history, were examined. In the second approach 20 MHz linear scanning combined with 20 MHz pulsed Doppler attached to the linear array was used. The radial artery FMD was normalized using shear rate at the radial artery wall.

Results and Conclusions:
For the “healthy” group, the FMD resulting from reactive hyperemia response was over 20%; while in the “atherosclerotic” group, the FMD was at least twice as small, not exceeding 10%. The shear rate (SR) normalized FMDSR was in the range from 7.8 to 9.9 in arbitrary units, while in patients with minor cardiac history FMDSR was clearly lower, 6.8 to 7.6. The normalized FMDSR of radial artery RARR can be an alternative to the brachial FMD where the precision of measurements is lower and the diameter dilation does not exceed 7-10%.

Keywords:
thick film transducers; atherosclerosis; flow mediated vasodilation

(6p.)
50.Piotrzkowska-Wroblewska H., Dobruch-Sobczak K., Litniewski J., Chrapowicki E., Roszkowska-Purska K., Nowicki A., Differentiation of the breast lesions using statistics of backscattered echoes, HYDROACOUSTICS, ISSN: 1642-1817, Vol.19, pp.319-328, 2016
Piotrzkowska-Wroblewska H., Dobruch-Sobczak K., Litniewski J., Chrapowicki E., Roszkowska-Purska K., Nowicki A., Differentiation of the breast lesions using statistics of backscattered echoes, HYDROACOUSTICS, ISSN: 1642-1817, Vol.19, pp.319-328, 2016

Abstract:
The purpose of this study was to evaluate the accuracy of statistical properties of the backscttered ultrasound in differential diagnosis of the breast lesions. The B-mode images together with the appropriate RF echoes from the breast lesions and surrounding tissues were collected. The RF data were processed for the statistics of the backscattered echo signals using K and Nakagami distributions characterized by the M and m parameters, respectively. Based on both, M and m parameters, a set of 18 parameters was derived.

From the point of view of the sensitivity of detection of the cancer the best score was obtained using maximum value of M parameter, the best specificity was received using the differential Nakagami parameter (the differential values between lesions and surrounding tissues). In conclusion the quantitative sonography is a method which has potential to be a complementary tool for classification of the breast lesions.

Keywords:
quantitative ultrasound, breast cancer, Nakagami distribution, K dstribution

(6p.)
51.Secomski W., Nowicki A., Generation and measurement of acoustic streaming in limited space, HYDROACOUSTICS, ISSN: 1642-1817, Vol.19, pp.361-368, 2016
Secomski W., Nowicki A., Generation and measurement of acoustic streaming in limited space, HYDROACOUSTICS, ISSN: 1642-1817, Vol.19, pp.361-368, 2016

Abstract:
The aim of this work was to use the streaming phenomena to assist clot dissolution in blood vessel. Such treatment is called sonothrombolysis. Acoustic streaming is a steady flow in a fluid driven by the acoustic wave propagating in a lossy medium. It is a non-linear effect and it depends on ultrasound intensity, and sound absorption in the media.

The source of ultrasound was a flat piezoceramic disc generating long pulses at 1 MHz frequency and 0.2 W/cm2 ITA acoustical intensity. The streaming was generated in a vessel simulating free space, and next repeated in a multi-well cell culture plate, and in the limited space inside the 8 mm diameter silicone tube positioned perpendicular to the ultrasonic beam. The tube was filled with a mixture of water, glycerol, and starch, so with acoustic properties similar to blood. The streaming velocity was recorded either by the Siemens Acuson Antares ultrasonic scanner operating in the color Doppler mode at 8.9 MHz, or by the custom built 20 MHz pulsed Doppler flowmeter.

The results obtained using both systems were very similar. The recorded streaming velocities were 3.2 cm/s, 6.1 cm/s and 0.3 cm/s, respectively. They were an order of magnitude smaller than that calculated theoretically. However, the results obtained confirm existence of streaming, even very close to the source, in the limited space. This effect will be explored in in-vitro experiments of blood clot dissolution within the tube simulating a blood vessel.

Keywords:
ultrasound, radiation force, blood, thrombolysis

(6p.)
52.Wójcik J., Byra M., Nowicki A., A spectral-based method for tissue characterization, HYDROACOUSTICS, ISSN: 1642-1817, Vol.19, pp.369-375, 2016
Wójcik J., Byra M., Nowicki A., A spectral-based method for tissue characterization, HYDROACOUSTICS, ISSN: 1642-1817, Vol.19, pp.369-375, 2016

Abstract:
Quantitative ultrasound methods are widely investigated as a promising tool for tissue characterization. In this paper, a novel quantitative method is developed which can be used to assess scattering properties of tissues. The proposed method is based on analysis of oscillations of the backscattered echo power spectrum. It is shown that these oscillations of the power spectrum are connected with the distances between scatterers within the medium. Two techniques are proposed to assess the scatterer’s distribution. First, we show that the inverse Fourier transform of the backscattered echo power spectrum corresponds to a histogram of the distances between scatterers. Second, the Hilbert-Huang transform is used to directly extract the power spectrum oscillations. Both methods are examined by means of a numerical experiment. A cellular gas model of a biological medium is considered. Results are presented and discussed. Both methods can be used to evaluate the scatterer’s distribution by means of the power spectrum oscillations.

Keywords:
quantitative ultrasound, signal analysis, wave scattering

(6p.)
53.Johansen K., Postema M., Lagrangian formalism for computing oscillations of spherically symmetric encapsulated acoustic antibubbles, HYDROACOUSTICS, ISSN: 1642-1817, Vol.19, pp.197-208, 2016
Johansen K., Postema M., Lagrangian formalism for computing oscillations of spherically symmetric encapsulated acoustic antibubbles, HYDROACOUSTICS, ISSN: 1642-1817, Vol.19, pp.197-208, 2016

Abstract:
Antibubbles are gas bubbles containing a liquid droplet core and, typically, a stabilising outer shell. It has been hypothesised that acoustically driven antibubbles can be used for active leakage detection from subsea production facilities. This paper treats the dynamics of spherically symmetric microscopic antibubbles, building on existing models of bubble dynamics. A more complete understanding of microbubble dynamics demands that the effects of the translational dynamics is included into the Rayleigh-Plesset equation, which has been the primary aim of this paper. Moreover, it is a goal of this paper to derive a theory that is not based on ad-hoc parameters due to the presence of a shell, but rather on material properties. To achieve a coupled set of differential equations describing the radial and translational dynamics of an antibubble, in this paper Lagrangian formalism is used, where a Rayleigh-Plesset-like equation allows for the shell to be modelled from first principles. Two shell models are adopted; one for a Newtonian fluid shell, and the other for a Maxwell fluid shell. In addition, a zero-thickness approximation of the encapsulation is presented for both models. The Newtonian fluid shell can be considered as a special case of the Maxwell fluid shell. The equations have been linearised and the natural and damped resonance frequencies have been presented for both shell models.

Keywords:
microbubbles, spatio–temporal bubble dynamics, Rayleigh-Plesset equation

(6p.)
54.Makowska K., Kowalewski Z.L., Ocena stopnia degradacji materiałów ferromagnetycznych technikami magnetycznymi, ENERGETYKA, PROBLEMY ENERGETYKI I GOSPODARKI PALIWOWO-ENERGETYCZNEJ, ISSN: 0013-7294, Vol.749, No.11, pp.681-684, 2016(4p.)
55.Konowrocki R., Evaluation of electromechanical coupling parameters of the railway vehicle electric drive system to condition monitoring of the drive., XXIV Francusko-Polskie Seminarium Mechaniki, 2016-10-17/10-18, Warszawa (PL), pp.1-2, 2016
Konowrocki R., Evaluation of electromechanical coupling parameters of the railway vehicle electric drive system to condition monitoring of the drive., XXIV Francusko-Polskie Seminarium Mechaniki, 2016-10-17/10-18, Warszawa (PL), pp.1-2, 2016

Abstract:
In the framework of studies there are presented results of numerical investigation of the electromechanical drive system of the railway vehicle. Here, electric parameters of the asynchronous motor are rated to condition monitoring of the drive. Evaluation of the parameters can be used to create guidelines to a monitoring system. Main informations about a torsional vibration of wheelsets generated by friction coefficient in wheel-rail zone are provided by electric parameters obtained from a dynamic electromechanical drive model. The vibrations of wheelsets generated by a self-excited vibration mechanism of wheel-rail contact systems is very harmful. Proposed approach is alternative solution for monitoring of the torsion vibration in considered driving system. Results of this analysis can be used in order to investigate the drive system’s sensitivity to torsional oscillations.

Keywords:
condition monitoring, electromechanical coupling, wheel-rail adhesion, wheelset drivetrain dynamic

56.Konowrocki R., Analysis of electromechanical interaction in an electric drive system used in the high speed trains, ART Conference 2016, ADVANCED RAIL TECHNOLOGIES - 5th International Conference, 2016-11-09/11-11, Warsaw (PL), pp.1-2, 2016
Konowrocki R., Analysis of electromechanical interaction in an electric drive system used in the high speed trains, ART Conference 2016, ADVANCED RAIL TECHNOLOGIES - 5th International Conference, 2016-11-09/11-11, Warsaw (PL), pp.1-2, 2016

Abstract:
A dynamic modelling of the electrical drive systems coupled with elements of a driven machine or vehicle is particularly important when the purpose of such modelling is to obtain an information about the transient phenomena of system operation, like a run-up, run-down and loss of adhesion in the wheel-rail zone. In this paper most attention is paid to the modelling of an electromechanical interaction between the electric driving motor and the railway wheelset. The knowledge about torsional vibrations in transmission systems of a high speed train (HST) is of a great importance in the fields dynamics of mechanical systems. Torsional vibrations in the railway vehicle drive train are generated by two main phenomena. To the first one belongs the electromechanical interaction between of the railway drive system including the: electric motor, gears, the driven part of disc clutch and driving parts of the gear clutch. To the second one belong torsional vibrations of the flexible wheels and wheelsets caused by variation of adhesion forces in the wheel-rail contact zone.

Keywords:
high speed train drive, electromechanical coupling, wheel-rail adhesion, asynchronous motor, electric motor

57.Konowrocki R., Groll W., Kukulski J., Walczak S., Temperature field analysis of brake discs for high speed train using infrared technology, ART Conference 2016, ADVANCED RAIL TECHNOLOGIES - 5th International Conference, 2016-11-09/11-11, Warsaw (PL), pp.1-2, 2016
Konowrocki R., Groll W., Kukulski J., Walczak S., Temperature field analysis of brake discs for high speed train using infrared technology, ART Conference 2016, ADVANCED RAIL TECHNOLOGIES - 5th International Conference, 2016-11-09/11-11, Warsaw (PL), pp.1-2, 2016

Abstract:
Thermoelastic instabilities are typically observed in frictional systems, which transform large quantity of kinetic energy into thermal energy. To this group we can include a high speed train brake system. This brake systems exposed to thermoelastic instabilities show a characteristic temperature distribution on break disc surface that can lead to local material change, vibrations of the braking system element coefficient of friction fluctuations. When reaching a critical sliding velocity, experiments show a nonhomogeneous and often periodic temperature distribution on the sliding surface. The mechanism of the phenomenon is caused by the interaction of heat generation and thermal expansion. A local rise in surface temperature results in a thermal expansion of the material nearby. Such a region of elevated temperature therefore is slightly higher than the surrounding topography and therefore carries a dominating part of the frictional load. A following rise in heat can destabilize the process. Two basic forms of thermoelastic instabilities can be commonly observed such as hot spots and hot bands.

Keywords:
high speed train braking, infrared technology, hot spotting, hot banding, brake disc, heat transfer

58.Walenta Z.A., Słowicka A.M., Extinguishing detonation in pipelines – optimization of the process, ISIS 2016, 22nd International Shock Interaction Symposium, 2016-07-04/07-08, Glasgow (GB), pp.1-5, 2016
59.Szymczak T., Kowalewski Z.L., Brodecki A., Determination of artificial defects in material under monotonic tension by the use of FEM and DIC methods, Materials Today: Proceedings, ISSN: 2214-7853, DOI: 10.1016/j.matpr.2016.03.011, No.3, pp.1171-1176, 2016
Szymczak T., Kowalewski Z.L., Brodecki A., Determination of artificial defects in material under monotonic tension by the use of FEM and DIC methods, Materials Today: Proceedings, ISSN: 2214-7853, DOI: 10.1016/j.matpr.2016.03.011, No.3, pp.1171-1176, 2016

Abstract:
The paper concerns numerical and experimental investigations carried out for determination of an influence of holes on material behaviour under monotonic tension. The 40Cr steel commonly applied in automotive and power plant branches of industry was tested. The analysis was performed by the use of analytical and Finite Element Method calculations. It enabled identification of stress concentration/maximum stress versus hole diameter relationships, and the HMH stress distribution. Full-field contactless Digital Image Correlation (DIC) system was used for capturing the effective strain variations from the beginning of test up to specimen fracture. It enabled us to indicate the most important stress concentrator, and moreover, distribution of the HMH effective strain in 2D coordinate system. A comparison of tensile characteristic obtained by means of smooth and perforated specimens showed 70% reduction of yield point and 50% lowering of elongation as an effect of the artificial defects introduced.

Keywords:
Monotonic tension, holes, steel, stress concentration factor, maximum stress, yield point, ductility, FEM, DIC

60.Grzywna P., Kukla D., Kowalewski Z., Kopeć M., Wyszkowski M., Assessment of fatigue damage development using the espi system, 27EMS, Experimental Mechanics of Solids - 27th Symposium, 2016-10-19/10-22, Jachranka (PL), pp.27, 2016
61.Majek K., Będkowski J., Range Sensors Simulation Using GPU Ray Tracing, CORES 2015, The 9th International Conference on Computer Recognition Systems CORES, 2015-05-25/05-27, Wrocław (PL), DOI: 10.1007/978-3-319-26227-7_78, No.403, pp.831-840, 2016
Majek K., Będkowski J., Range Sensors Simulation Using GPU Ray Tracing, CORES 2015, The 9th International Conference on Computer Recognition Systems CORES, 2015-05-25/05-27, Wrocław (PL), DOI: 10.1007/978-3-319-26227-7_78, No.403, pp.831-840, 2016

Abstract:
In this paper the GPU-accelerated range sensors simulation is discussed. Range sensors generate large amount of data per second and to simulate these high-performance simulation is needed. We propose to use parallel ray tracing on graphics processing units to improve the performance of range sensors simulation. The multiple range sensors are described and simulated using NVIDIA OptiX ray tracing engine. This work is focused on the performance of the GPU acceleration of range images simulation in complex environments. Proposed method is tested using several state-of-the-art ray tracing datasets. The software is publicly available as an open-source project SensorSimRT.

Keywords:
Ray tracing, RGB-D sensors, Simulation

62.Chikahiro Y., Ario I., Holnicki-Szulc J., Pawłowski P., Graczykowski C., A Study on Optimal Reinforcement of Scissor Type of Bridge with Additional Strut Members, ICCEE 2016, International Conference on Civil and Environmental Engineering, 2016-10-17/10-19, Hiroshima (JP), pp.1-2, 2016
Chikahiro Y., Ario I., Holnicki-Szulc J., Pawłowski P., Graczykowski C., A Study on Optimal Reinforcement of Scissor Type of Bridge with Additional Strut Members, ICCEE 2016, International Conference on Civil and Environmental Engineering, 2016-10-17/10-19, Hiroshima (JP), pp.1-2, 2016

Keywords:
scissor type of bridge, emergency bridge, strut reinforcement, sectional optimization

63.Takeda K., Matsui R., Tobushi H., Pieczyska E.A., Subloop deformation of shape memory alloy, SolMech 2016, 40th Solid Mechanics Conference, 2016-08-29/09-02, Warszawa (PL), No.P059, pp.1-2, 2016
Takeda K., Matsui R., Tobushi H., Pieczyska E.A., Subloop deformation of shape memory alloy, SolMech 2016, 40th Solid Mechanics Conference, 2016-08-29/09-02, Warszawa (PL), No.P059, pp.1-2, 2016

Abstract:
Shape memory alloys (SMAs) are remarkable materials characterized by the thermomechanical properties of shape memory effect and superelasticity. Since the properties like these characteristics are highly conducive to the functions of smart materials, their applications have attracted worldwide attention. The functional properties of an SMA appear based on the martensitic transformation (MT). Research up to now in this area has been mainly concerned with a full loop (or perfect loop) of the MT completion. However, in practical applications, temperature and stress are likely to vary in various ranges. If SMA elements are subjected to loads with a subloop (or partial loop, internal loop) in which temperature or stress varies in an incomplete MT range, the conditions for the start and finish of the MT as in a full loop are not satisfied. The present paper investigates superelastic deformation behaviors of TiNi alloy in various subloop loading conditions, in particular the dependence of the subloop deformation on the loading rate, and the characteristics of transformation-induced creep in the stress plateau region under constant stress.

Keywords:
Shape memory alloy, subloop deformation, temperature distribution, pseudoelastic behaviour

64.Takeda K., Matsui R., Tobushi H., Pieczyska E.A., Design of rotary driving actuator by using torsional deformation of SMA tapes, SolMech 2016, 40th Solid Mechanics Conference, 2016-08-29/09-02, Warszawa (PL), No.P057, pp.1-2, 2016
Takeda K., Matsui R., Tobushi H., Pieczyska E.A., Design of rotary driving actuator by using torsional deformation of SMA tapes, SolMech 2016, 40th Solid Mechanics Conference, 2016-08-29/09-02, Warszawa (PL), No.P057, pp.1-2, 2016

Abstract:
One of the main materials which have activated the research on the smart materials is shape memory alloy (SMA). The main characteristics of SMA are the shape memory effect (SME) and superelasticity (SE). In a recent study using the torsional deformation of a TiNi SMA tube, twist in the blades of rotary aircraft was investigated in order to improve the flight performance. In practical applications making use of SMA tapes, torsional deformation can be obtained simply by gripping both ends without any mechanical process. In the present study, in order to develop the rotary driving actuators of SMA tapes, the torsional deformation properties of TiNi SMA tapes are investigated. The graphical method to design the two-way rotary driving actuator by using torsional deformation of SMA tapes is proposed.

Keywords:
Shape memory alloy, torsion, rotary driving, actuator

65.Ekiel-Jeżewska M.L., Słowicka A.M., Wajnryb E., Dynamics of flexible fibers in shear flows, Flowing matter, 2016-01-11/01-15, Porto (PT), pp.74-75, 2016
66.Frąś T., Roth M., Pawłowski P., Thermo-viscoplastic behavior of AA7020-T651 in application for modeling of dynamic loadings, ICCEE 2016, International Conference on Civil and Environmental Engineering, 2016-10-17/10-19, Hiroshima (JP), pp.1-8, 2016
Frąś T., Roth M., Pawłowski P., Thermo-viscoplastic behavior of AA7020-T651 in application for modeling of dynamic loadings, ICCEE 2016, International Conference on Civil and Environmental Engineering, 2016-10-17/10-19, Hiroshima (JP), pp.1-8, 2016

Abstract:
The stress–strain behavior of the rolled AA7020 aluminum tempered in T651 conditions is studied at various strain rates and temperatures. Basing on tensile, shear and compression tests, the effects of strain and strain-rate hardening, thermal softening and plastic anisotropy are discussed. The parameters of the thermo-viscoplastic flow and fracture models proposed by Johnson and Cook are identified and validated basing on the numerical modeling.
The obtained constitutive relations may be applied to model more complex states of stresses resulted from different loading conditions.

Keywords:
AA7020-T651, flow and fracture models, metals under dynamic loadings, numerical simulation of metal deformation

67.Skłodowski M., Pawłowski P., Smartphone aided structural monitoring and measurements, SAHC 2106, Structural Analysis of Historical Constructions, 2016-09-13/09-15, Leuven (BE), pp.140-144, 2016
Skłodowski M., Pawłowski P., Smartphone aided structural monitoring and measurements, SAHC 2106, Structural Analysis of Historical Constructions, 2016-09-13/09-15, Leuven (BE), pp.140-144, 2016

Abstract:
Environmental and mechanical quantities need to be measured and registered in order to provide engineers and researchers with data required for diagnostics of heritage structures' condition. Analysis of the needs of diagnostic measurements and monitoring of historic structures shows that a large number of structures should be supervised. However hardware costs and resources needed to implement existing technologies constitute a barrier for a wide usage of modern sensors. The presented research shows that everyday usage of smartphones can be extended into a technology suitable for technical diagnostic purposes. Smartphone has many intrinsic sensors factory installed so it is already a sensing device. By calibrating the sensors the smartphone can be upgraded from being a sensing device to become the real measuring equipment. This emerging technology called Smartphone Aided Structural Monitoring and Measurements (SASMM) is not limited to the examples presented in this paper.

68.Marijnissen M.J., Rojek J., Particle-fluid interaction inside a beater mill, XXII Fluid Mechanics Conference, 2016-09-11/09-14, Słok k/Bełchatowa (PL), pp.127-128, 2016
Marijnissen M.J., Rojek J., Particle-fluid interaction inside a beater mill, XXII Fluid Mechanics Conference, 2016-09-11/09-14, Słok k/Bełchatowa (PL), pp.127-128, 2016

Abstract:
In this work a trajectory study of copper ore particles through a fan mill was performed with the use of a commercial CFD code, ANSYS Fluent, coupled with DEM (Discrete Element Method). Particles of different sizes were analysed. Results highlight ore behaviour, fluid flow conditions and mark places requiring geometrical improvements.

Keywords:
CFD, DEM, Beater mill

69.Golasiński K., Pieczyska E., Maj M., Staszczak M., Takesue N., Investigation of Gum Metal under compressive cyclic loading, Plastmet 2016, Jubileuszowe X Seminarium Naukowe ZINTEGROWANE STUDIA PODSTAW DEFORMACJI PLASTYCZNEJ METALI , 2016-11-22/11-25, Łańcut (PL), pp.41-42, 2016
Golasiński K., Pieczyska E., Maj M., Staszczak M., Takesue N., Investigation of Gum Metal under compressive cyclic loading, Plastmet 2016, Jubileuszowe X Seminarium Naukowe ZINTEGROWANE STUDIA PODSTAW DEFORMACJI PLASTYCZNEJ METALI , 2016-11-22/11-25, Łańcut (PL), pp.41-42, 2016

Abstract:
Preliminary results of mechanical behavior of Gum Metal compressed along the swaging direction during cyclic loading were presented. The unique mechanical performance of Gum Metal - low Young’s Modulus and high strength were confirmed. During the cyclic loading the curves profiles change significantly with each cycle and reveal a clearly pronounced yield points for the 4th and further cycles. Compression tests along perpendicular direction to the swaging one will be considered for our future research.

Keywords:
Gum Metal, polycrystal, compression loading, cyclic loading, digital image correlation

70.Nalepka P., Nalepka K., Pęcherski R.B., Analysis of deformation mechanisms in Cu /Al2O3 interfaces with the use of HRTEM images , SolMech 2016, 40th Solid Mechanics Conference, 2016-08-29/09-02, Warszawa (PL), No.P243, pp.1-2, 2016
Nalepka P., Nalepka K., Pęcherski R.B., Analysis of deformation mechanisms in Cu /Al2O3 interfaces with the use of HRTEM images , SolMech 2016, 40th Solid Mechanics Conference, 2016-08-29/09-02, Warszawa (PL), No.P243, pp.1-2, 2016

Abstract:
The composition of metal with ceramics is applied to many devices, structural elements of machines as well as their equipment. Therefore, evaluating the strength of interfaces of this type becomes an important scientific issue of fundamental character. Numerous attempts are made to solve the posed problem, both experimental and theoretical ones. The presented approach enables local, more precise determining the mechanical properties of interfaces. The basis of conducted calculations is the geometry of the interface strongly preferred by the considered system of materials. It is defined by the mutual orientation of crystallites of two phases and the position of the plane boundary. The combination of two advanced research methods: electron back-scatter diffraction (EBSD) and high resolution transmission electron microscopy (HRTEM) enables identification of this crucial characteristics. The second of them additionally reveals a representative microstructure of the interface in the form of a projection. We reconstruct it in three dimensions by means of molecular dynamics (MD) simulations. In this way, we identify deformation mechanisms that enable the formation of the bonding between the metallic phase and ceramic one.

Keywords:
nanocomposites, deformation in interface, HRTEM

71.Frąś L.J., Jarząbek D., Dziekoński C., Pęcherski R.B., Viscoplastic deformation of magnethoreological solids , SolMech 2016, 40th Solid Mechanics Conference, 2016-08-29/09-02, Warszawa (PL), No.P244, pp.1-2, 2016
Frąś L.J., Jarząbek D., Dziekoński C., Pęcherski R.B., Viscoplastic deformation of magnethoreological solids , SolMech 2016, 40th Solid Mechanics Conference, 2016-08-29/09-02, Warszawa (PL), No.P244, pp.1-2, 2016

Abstract:
The microsized (~10µm) ferroelements build the structure of magenthoreological (MR) fluid. This two phase material in neutral state behaves as a fluid but in magnetic field becomes a solid and has properties of elasto-viscoplastic material. This is due to the skeleton made by ferrolements connected into braids. The aim of the paper is to identify the physical mechanisms of deformation of such a structure with use of own set up for in situ microscopic observations.

Keywords:
magnethoreological solids, viscoplasticity, ferroelements, compression test, shear banding

72.Makowska K., Kowalewski Z.L., Application of Barkhausen Noise for Assessments of Damage in Ferromagnetic Materials with Negative Magnetocrystalline Anisotropy Constant, 27EMS, Experimental Mechanics of Solids - 27th Symposium, 2016-10-19/10-22, Jachranka (PL), pp.40, 2016
73.Szymczak T., Kowalewski Z.L., Brodecki A., An Influence of Strain Rate and Artificial Defects on Material Behaviour During Tension, 27EMS, Experimental Mechanics of Solids - 27th Symposium, 2016-10-19/10-22, Jachranka (PL), pp.55, 2016
74.Frydrych K., Kowalczyk-Gajewska K., Modelling microstructure evolution in SPD processes in the framework of crystal plasticity theory, ICTAM XXIV, 24th International Congress of Theoretical and Applied Mechanics, 2016-08-21/08-26, Montréal (CA), pp.1-2, 2016
75.Brzozowski B., Rochala Z., Wojtowicz K., Gawełda B., Kaźmierczak K., Miniature Airflow Probe for an Unmanned Aerial Vehicle, 3rd IEEE International Workshop on Metrology for Aerospace, 2016-06-21/06-23, Florence (IT), DOI: 10.1109/MetroAeroSpace.2016.7573266, pp.500-505, 2016
Brzozowski B., Rochala Z., Wojtowicz K., Gawełda B., Kaźmierczak K., Miniature Airflow Probe for an Unmanned Aerial Vehicle, 3rd IEEE International Workshop on Metrology for Aerospace, 2016-06-21/06-23, Florence (IT), DOI: 10.1109/MetroAeroSpace.2016.7573266, pp.500-505, 2016

Abstract:
This paper presents in details design and development of a probe for measuring airflow data for an unmanned aerial vehicle (UAV). The research regards the definition of the requirements and dimensions of the device and limits the measurements to selected aerodynamic parameters only. In the design concept the five parameters gauged in the two independent sections of the probe were envisaged. In the first section temperature, stagnation and static pressure and in the second section flow angles - sideslip and angle of attack (AoA) were determined. The development has been divided into three stages. The first stage included a formulation of the guidelines for the construction of the mechanical elements. The specified requirements included the maximum size of the probe and the resultant restriction on the size of the sensors and their electronics hardware circuits. The next stage was focused on sensors selection and electronics hardware development. Additionally, an appropriate microcontroller system for sensors control and data acquisition was developed. The final stage included formulation of a software algorithm and its implementation. Eventually, the probe was installed on a mini UAV for inflight tests which verified the correctness of the design.

Keywords:
Probes, Electron tubes, Temperature measurement, Aerodynamics, Sensors, Blades, Unmanned aerial vehicles

76.Brzozowski B., Kaźmierczak K., Rochala Z., Wojda M., Wojtowicz K., A concept of UAV indor navigation system based on magnetic field measuements, 3rd IEEE International Workshop on Metrology for Aerospace, 2016-06-21/06-23, Florence (IT), DOI: 10.1109/MetroAeroSpace.2016.7573291, pp.636-640, 2016
Brzozowski B., Kaźmierczak K., Rochala Z., Wojda M., Wojtowicz K., A concept of UAV indor navigation system based on magnetic field measuements, 3rd IEEE International Workshop on Metrology for Aerospace, 2016-06-21/06-23, Florence (IT), DOI: 10.1109/MetroAeroSpace.2016.7573291, pp.636-640, 2016

Abstract:
This paper presents a conception of an indoor positioning system for an unmanned aerial vehicle (UAV). The measurement of magnetic field is a main source of information required to estimate a position of the platform. It is a parameter which can be measured with affordable sensors and is easy to obtain. In order to use acquired data, a magnetic field map of the specified environment should be previously determined. Thus, a few ideas of using this information were elaborated. First of all, dedicated hardware had to be designed to implement the method. In this process, a multipurpose measurement system was developed. The measurement system consists of three axis digital magnetometers and battery powered microprocessor system with SD memory card and LCD display. The module was installed on the specially designed chassis that enable testing on 3 different heights. The verification tests were performed in designated room, where permanent magnets were used to modify local magnetic field that could work as beacons.

Keywords:
Magnetic field measurement, Magnetic fields, Magnetometers, Earth, Unmanned aerial vehicles, Sensors, Sea measurements

77.Kowalczyk-Gajewska K., The self-consistent sequential averaging scheme for modelling elastic-viscoplastic polycrystals: validation by finite element calculations, MTDM, The 10th International Conference on Mechanics of Time Dependent Materials, 2016-05-17/05-20, Paris (FR), pp.63-64, 2016
Kowalczyk-Gajewska K., The self-consistent sequential averaging scheme for modelling elastic-viscoplastic polycrystals: validation by finite element calculations, MTDM, The 10th International Conference on Mechanics of Time Dependent Materials, 2016-05-17/05-20, Paris (FR), pp.63-64, 2016

Keywords:
Micromechanics, Sequential linearization, Self-Consistent Scheme, Polycrystals, Finite Element

78.Sadowski P., Kowalczyk-Gajewska K., Stupkiewicz S., Efficient algorithmic treatment of the incremental Mori–Tanaka scheme for elasto-plastic composites, SolMech 2016, 40th Solid Mechanics Conference, 2016-08-29/09-02, Warszawa (PL), No.P070, pp.1-2, 2016
79.Wcisło B., Mucha M., Kowalczyk-Gajewska K., Pamin J., Large strain thermo-elasto-plasticity: simulation of shear banding for different stress states, SolMech 2016, 40th Solid Mechanics Conference, 2016-08-29/09-02, Warszawa (PL), No.P169, pp.1-2, 2016
80.Kowalczyk-Gajewska K., Frydrych K., Modelling of microstructure evolution in metals and alloys of high specific strength, SolMech 2016, 40th Solid Mechanics Conference, 2016-08-29/09-02, Warszawa (PL), No.P196, pp.1-2, 2016
81.Żuk J.P., Wajnryb E., From rheology to molecular detail - viscosity of suspension of complex molecules, ICTAM XXIV, 24th International Congress of Theoretical and Applied Mechanics, 2016-08-21/08-26, Montréal (CA), pp.1256-1257, 2016
Żuk J.P., Wajnryb E., From rheology to molecular detail - viscosity of suspension of complex molecules, ICTAM XXIV, 24th International Congress of Theoretical and Applied Mechanics, 2016-08-21/08-26, Montréal (CA), pp.1256-1257, 2016

Abstract:
The viscosity of solution is intrinsically connected with its composition and the properties of individual particles. For complex macromolecules there often exist coupling between the flow and the state of the molecule. The distribution of particle shapes and movements reacts to the external flow and the flow reacts to this distribution change. This coupling determines the amount of stress induced by the molecules immersed in the fluid that results in change of the viscosity. Using the Rotne-Prager Yamakawa approximation we show, that given molecular model, one can infer the details of the molecules based on rheology of the solution.

82.Wiśniewski K., Turska E., Recent results on nine-node shell elements using two-level approximation of strain, SolMech 2016, 40th Solid Mechanics Conference, 2016-08-29/09-02, Warszawa (PL), No.P122, pp.1-2, 2016
Wiśniewski K., Turska E., Recent results on nine-node shell elements using two-level approximation of strain, SolMech 2016, 40th Solid Mechanics Conference, 2016-08-29/09-02, Warszawa (PL), No.P122, pp.1-2, 2016

Keywords:
finite element method, shell elements

83.Jarzębski P., Wiśniewski K., Evaluation of partial factorization for condensation of shell and solid-shell elemental matrices, SolMech 2016, 40th Solid Mechanics Conference, 2016-08-29/09-02, Warszawa (PL), No.P100, pp.1-2, 2016
Jarzębski P., Wiśniewski K., Evaluation of partial factorization for condensation of shell and solid-shell elemental matrices, SolMech 2016, 40th Solid Mechanics Conference, 2016-08-29/09-02, Warszawa (PL), No.P100, pp.1-2, 2016

Keywords:
finite element methods, solid-shell elements

84.Szolc T., Falkowski K., Henzel M., Kurtyna-Mazurek P., Passive and active stabilization of the electro-dynamic magnetic bearings supporting high-speed rotors, VITM 11, VITM 11 - Vibrations In Rotating Machinery, IMechE, 2016-09-13/09-15, Machester (GB), pp.721-731, 2016
Szolc T., Falkowski K., Henzel M., Kurtyna-Mazurek P., Passive and active stabilization of the electro-dynamic magnetic bearings supporting high-speed rotors, VITM 11, VITM 11 - Vibrations In Rotating Machinery, IMechE, 2016-09-13/09-15, Machester (GB), pp.721-731, 2016

Abstract:
The electrodynamic passive magnetic bearings became now a very promising kind of support for high-speed rotors. Nevertheless, because of skew-symmetrical visco-elastic properties of such bearings, they are sensitive to operational instability. In order to avoid this disadvantage, in the paper there are proposed stabilization concepts reducing to an introduction of a sufficient magnitude of additional external damping into the vibrating rotor-shaft system. This purpose is going to be realized by means of simple and effective passive dampers built in the electrodynamic bearing housings as well as using heteropolar magnetic dampers which realize operational principles of the active magnetic bearing. The theoretical investigations are going to be carried out by means of a structural computer model of the rotor-shaft system, taking into consideration its full geometry and material properties.

85.Hołobut P., Chodkiewicz P., Macios A., Lengiewicz J., Internal localization algorithm based on relative positions for cubic-lattice modular-robotic ensembles, IROS, IROS 2016 - IEEE/RSJ International Conference on Intelligent Robots and Systems, 2016-10-09/10-14, Daejeon Convention Center (DCC), Daejeon, South Korea (KP), DOI: 10.1109/IROS.2016.7759473, pp.3056-3062, 2016
Hołobut P., Chodkiewicz P., Macios A., Lengiewicz J., Internal localization algorithm based on relative positions for cubic-lattice modular-robotic ensembles, IROS, IROS 2016 - IEEE/RSJ International Conference on Intelligent Robots and Systems, 2016-10-09/10-14, Daejeon Convention Center (DCC), Daejeon, South Korea (KP), DOI: 10.1109/IROS.2016.7759473, pp.3056-3062, 2016

Abstract:
Module localization is an important aspect of the operation of self-reconfigurable robots. The knowledge of spatial positions of modules, or at least of the overall shape which the modules form, is the usual prerequisite for reconfiguration planning. We present a general, decentralized algorithm for determining the positions of modules placed on a cubic grid from local sensor information. The connection topology of the robot is arbitrary. We assume that a module can sense the presence of its immediate neighbors on the grid and determine their positions in its own local coordinate system, but cannot sense the orientations of the coordinate systems of its neighbors. Since orientation cannot be directly communicated between modules, the modules can only exchange information about the relative positions of their neighbors. The algorithm aggregates this information over the entire network of modules and narrows down the set of valid positions for each module as far as possible. If there exists a unique locally-consistent assignment of coordinates to all modules then it is found.

86.Faraj R., Holnicki-Szulc J., Knap L., Seńko J., Mitigation of the structure response based on inertial shock-absorber, EACS2016, 6th European Conference on Structural Control, 2016-07-11/07-13, Sheffield (GB), pp.1, 2016
Faraj R., Holnicki-Szulc J., Knap L., Seńko J., Mitigation of the structure response based on inertial shock-absorber, EACS2016, 6th European Conference on Structural Control, 2016-07-11/07-13, Sheffield (GB), pp.1, 2016

Abstract:
The goal of this paper is to present further development of the inertial shock-absorber called SPINMAN. Application of the device in mitigation of structures response is investigated and selected case study is discussed. The specific construction and operation of the device is introduced and explained. In reference to the impact absorption problems, the SPIN-MAN is a concept of adaptive inerter device with two phases of operation. The first of them includes energy absorption and accumulation. External energy of the load is converted to kinetic energy of rotational motion of the mass. During the second phase, accumulated energy is dissipated by inverse spinning of the second mass powered by the remaining part of the impact energy. To obtain this type of operation, special switchable actuators are used. Applicability of the device in mitigation of impact-born structure response, especially in case of space systems, is investigated. General concept of the device construction and operation is adjusted to meet the requirements for space systems. This results in a fluidless, passive-like solution but adaptable to the load conditions. Tuning of the shock-absorber may be realized by manual or easily automated mechanical adjustments. Effectiveness of the solution is based on the specific on/off type of control, which is responsible for the optimal energy flow in the system and efficient dissipation of impact energy inside the SPIN-MAN. Results of numerical simulations confirmed quick and effective operation of this device.

Keywords:
structure response mitigation, adaptive impact absorption, adaptive inerter, semi-active control, shock-absorber

87.Frąś T., Roth M., Pawłowski P., Thermo-viscoplastic behavior of AA7020-T651 in application for modeling of dynamic loadings, ICCEE 2016, International Conference on Civil and Environmental Engineering, 2016-10-17/10-19, Hiroshima (JP), pp.1-2, 2016
Frąś T., Roth M., Pawłowski P., Thermo-viscoplastic behavior of AA7020-T651 in application for modeling of dynamic loadings, ICCEE 2016, International Conference on Civil and Environmental Engineering, 2016-10-17/10-19, Hiroshima (JP), pp.1-2, 2016

Abstract:
The stress–strain behavior of the rolled AA7020 aluminum tempered in T651 conditions is studied at various strain rates and temperatures. Basing on tensile, shear and compression tests, the effects of strain and strain-rate hardening, thermal softening and plastic anisotropy are discussed. The parameters of the thermo-viscoplastic flow and fracture models proposed by Johnson and Cook are identified and validated basing on the numerical modeling.
The obtained constitutive relations may be applied to model more complex states of stresses resulted from different loading conditions.

Keywords:
AA7020-T651, flow and fracture models, metals under dynamic loadings, numerical simulation of metal deformation

88.Urbanek O., Sajkiewicz P., The effect of polarity on biomimetic surface modification of PCL/chitosan nanofibers formed by electrospinning, ELECTROSPIN 2016, 4th International Conference on Electrospinning, 2016-06-28/07-01, Otranto (IT), pp.1, 2016
89.Urbanek O., Sajkiewicz P., Schauer C., Charge Assisted Tailoring and its Effect on Surface Modification of Chitosan Nanofibers, Fiber Society 2016 Fall Meeting and Technical Conference, 2016-10-10/10-12, Ithaca (US), pp.1, 2016
90.Konowrocki R., Kukulski J., Hot bands on a surface of brake discs used in the high speed trains- experimental investigation, FRICTION 2016”, IX International Conference Modeling And Simulation of The Friction Phenomena in the Physical and Technical Systems „FRICTION 2016” , 2016-10-18/10-18, Warsaw (PL), pp.1, 2016
Konowrocki R., Kukulski J., Hot bands on a surface of brake discs used in the high speed trains- experimental investigation, FRICTION 2016”, IX International Conference Modeling And Simulation of The Friction Phenomena in the Physical and Technical Systems „FRICTION 2016” , 2016-10-18/10-18, Warsaw (PL), pp.1, 2016

Abstract:
The heat produced between friction couple during braking induces thermal distortion in the disc and leads to appearance of hot bands. The Hot bands are generated by thermoelastic phenomena appearing in systems with high energy dissipation like brake or clutch systems. Systems exposed to thermoelastic instabilities show a characteristic temperature distribution that can lead to local material change, vibrations of the braking system element or coefficient of friction fluctuations. In the framework of studies there are presented results of experimental investigation on influence of the hot bands on properties of friction pair elements and parameters of the high-speed train brake system.

Keywords:
heat produced, friction coupling, breaking, hot bands, thermoelastic phenomena, friction fluctuations

91.Mucha Z., Widłaszewski J., Kurp P., Mulczyk K., Mechanically assisted laser forming of thin beams, Proceedings of SPIE, ISSN: 0277-786X, DOI: 10.1117/12.2262114, Vol.10159, pp.10159 0U-1-10, 2016
Mucha Z., Widłaszewski J., Kurp P., Mulczyk K., Mechanically assisted laser forming of thin beams, Proceedings of SPIE, ISSN: 0277-786X, DOI: 10.1117/12.2262114, Vol.10159, pp.10159 0U-1-10, 2016

Abstract:
Laser-assisted forming techniques have been developed in recent years to aid plastic working of materials, which are difficult in processing at normal temperatures due to a high brittleness, effects of high work-hardening or a high spring-back phenomenon. This paper reports initial experimental investigations and numerical simulations of a mechanically-assisted laser forming process. The research is aimed at facilitating plastic shaping of thin-walled parts made of high temperature resistant alloys. Stainless steel plate, 1 mm thick, 20 mm wide, was mounted in the cantilever arrangement and a gravitational load was applied to its free end. A CO2 laser beam with rectangular cross-section traversed along the plate, towards the fixed edge. Laser spot covered the whole width of the plate. Experiments and simulations using the finite element method were performed for different values of mechanical load and with constant laser processing parameters. Experimentally validated numerical model allowed analysis of plastic deformation mechanism under the hybrid thermo-mechanical processing. The revealed mechanism of deformation consists in intense material plastic flow near the laser heated surface. This behavior results mainly from the tension state close to the heated surface and the decrease of material yield stress at elevated temperature. Stress state near the side edges of the processed plate favored more intense plastic deformation and the involved residual stress in this region. © (2016) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.

Keywords:
laser forming, laser-assisted forming, FEA, thin-walled structure

92.Kuś W., Mrozek A., Burczyński T., Memetic Optimization of Graphene-Like Materials on Intel PHI Coprocessor, Lecture Notes in Artificial Intelligence, ISSN: 0302-9743, DOI: 10.1007/978-3-319-39378-0_35, Vol.9692, pp.401-410, 2016
Kuś W., Mrozek A., Burczyński T., Memetic Optimization of Graphene-Like Materials on Intel PHI Coprocessor, Lecture Notes in Artificial Intelligence, ISSN: 0302-9743, DOI: 10.1007/978-3-319-39378-0_35, Vol.9692, pp.401-410, 2016

Abstract:
The paper is devoted to the optimization of energy of carbon based atomic structure with use of the memetic algorithm. The graphene like atoms structure is coded into floating point genes and underwent evolutionary changes. The global optimization algorithm is supported by local gradient based improvement of chromosomes. The optimization problem is solved with the use of Intel PHI (Intel Many Integrated Core Architecture – Intel MIC). The example of optimization and speedup measurement for parallel optimization are given in the paper.

Keywords:
Parallel computing, Intel PHI, Optimization, Graphene-like materials

93.Burczyński T., Mrozek A., Kuś W., Computational models of new graphene-like nano-structures, SolMech 2016, 40th Solid Mechanics Conference, 2016-08-29/09-02, Warszawa (PL), No.P253, pp.1-2, 2016
Burczyński T., Mrozek A., Kuś W., Computational models of new graphene-like nano-structures, SolMech 2016, 40th Solid Mechanics Conference, 2016-08-29/09-02, Warszawa (PL), No.P253, pp.1-2, 2016

Keywords:
carbon nano-structures, conjugated gradient method, evolutionary algorithm

94.Burczyński T., Mrozek A., Kuś W., Generation of graphene-like atoms structures by means of memetic algorithms, ECCOMAS 2016, European Congress on Computational Methods in Applied Sciences and Engineering, 2016-06-05/06-10, Hersonissos (GR), No.9447, pp.1, 2016
Burczyński T., Mrozek A., Kuś W., Generation of graphene-like atoms structures by means of memetic algorithms, ECCOMAS 2016, European Congress on Computational Methods in Applied Sciences and Engineering, 2016-06-05/06-10, Hersonissos (GR), No.9447, pp.1, 2016

Keywords:
carbon nano-structures, atom structures, memetic algorithms

95.Konowrocki R., Kukulski J., Walczak S., Generowanie gorących punktów w badaniach tribologicznych par ciernych hamulca kolejowego, POJAZDY SZYNOWE 2016, XXII SCIENTIFIC CONFERENCE RAIL VEHICLES - XXII KONFERENCJA NAUKOWA POJAZDY SZYNOWE, 2016-05-30/06-01, Bydgoszcz - Gniew (PL), pp.22-22, 2016
Konowrocki R., Kukulski J., Walczak S., Generowanie gorących punktów w badaniach tribologicznych par ciernych hamulca kolejowego, POJAZDY SZYNOWE 2016, XXII SCIENTIFIC CONFERENCE RAIL VEHICLES - XXII KONFERENCJA NAUKOWA POJAZDY SZYNOWE, 2016-05-30/06-01, Bydgoszcz - Gniew (PL), pp.22-22, 2016

Abstract:
Ciepło generowane w parach ciernych układów hamulcowych podczas szybkiego hamowania prowadzi często do pojawienia się gorących punktów (ang. hot-spots) na ich powierzchniach. Charakter i zakres intensywności tego zjawiska zależą w dużym stopniu od właściwości mechanicznych i termicznych materiałów takich par. Rozkład temperatury w elementach takich układach ciernych wpływa na ich zniekształcenia cieplne, inicjujące powyższe zjawisko. W pracy przedstawiono wyniki badań uzyskanych na obiektach układu hamulcowego pojazdów szynowych, przedstawiające takie zjawisko. Próby doświadczalne ilustrujące charakter przegrzanych obszarów w parach ciernych, wykonywano na stanowisku do badań hamulców w aplikacjach kolejowych. Do analizy rozkładu temperatur w badanych układach użyto kilku metod pomiarowych.

Keywords:
gorące punkty, układ hamulcowy, tarcie, hotspot, pojazdy dużych prędkości

96.Konowrocki R., Walczak S., Wysocki G., Experimental and numerical investigation of flexibility of railway wheels and wheelsets, POJAZDY SZYNOWE 2016, XXII SCIENTIFIC CONFERENCE RAIL VEHICLES - XXII KONFERENCJA NAUKOWA POJAZDY SZYNOWE, 2016-05-30/06-01, Bydgoszcz - Gniew (PL), pp.33-33, 2016
Konowrocki R., Walczak S., Wysocki G., Experimental and numerical investigation of flexibility of railway wheels and wheelsets, POJAZDY SZYNOWE 2016, XXII SCIENTIFIC CONFERENCE RAIL VEHICLES - XXII KONFERENCJA NAUKOWA POJAZDY SZYNOWE, 2016-05-30/06-01, Bydgoszcz - Gniew (PL), pp.33-33, 2016

Abstract:
The paper is devoted to the experimental and theoretical analysis of influence of elastic properties of wheelset stiffness on the vehicle-track interaction. Results of experimental measurements stiffness of wheelsets are shown. Some types of wheelsets are considered with different wheel-plate design. Exemplary simulation of railway vehicle interaction with flexible and rigid model of the wheelset is presented.

Keywords:
vibration, structural flexibility, railway wheelset, experimental investigation, numerical analysis

97.Zakrzewska K.E., Samluk A., Wierzbicki M., Jaworski S., Kutwin M., Sawosz E., Chwalibog A., Pijanowska D.G., Pluta K.D., Analysis of the Cytotoxicity of Carbon-Based Nanoparticles, Diamond and Graphite, in Human Glioblastoma and Hepatoma Cell Lines, PLOS ONE, ISSN: 1932-6203, DOI: 10.1371/journal.pone.0122579, Vol.10, No.3, pp.1-15, 2015
Zakrzewska K.E., Samluk A., Wierzbicki M., Jaworski S., Kutwin M., Sawosz E., Chwalibog A., Pijanowska D.G., Pluta K.D., Analysis of the Cytotoxicity of Carbon-Based Nanoparticles, Diamond and Graphite, in Human Glioblastoma and Hepatoma Cell Lines, PLOS ONE, ISSN: 1932-6203, DOI: 10.1371/journal.pone.0122579, Vol.10, No.3, pp.1-15, 2015

Abstract:
Nanoparticles have attracted a great deal of attention as carriers for drug delivery to cancer cells. However, reports on their potential cytotoxicity raise questions of their safety and this matter needs attentive consideration. In this paper, for the first time, the cytotoxic effects of two carbon based nanoparticles, diamond and graphite, on glioblastoma and hepatoma cells were compared. First, we confirmed previous results that diamond nanoparticles are practically nontoxic. Second, graphite nanoparticles exhibited a negative impact on glioblastoma, but not on hepatoma cells. The studied carbon nanoparticles could be a potentially useful tool for therapeutics delivery to the brain tissue with minimal side effects on the hepatocytes. Furthermore, we showed the influence of the nanoparticles on the stable, fluorescently labeled tumor cell lines and concluded that the labeled cells are suitable for drug cytotoxicity tests.

(40p.)
98.Bogacz R., Kurnik W., On some rotor-dynamical phenomena of high-speed trains, ARCHIVE OF APPLIED MECHANICS, ISSN: 0939-1533, DOI: 10.1007/s00419-014-0966-3, Vol.85, No.9, pp.1343-1352, 2015
Bogacz R., Kurnik W., On some rotor-dynamical phenomena of high-speed trains, ARCHIVE OF APPLIED MECHANICS, ISSN: 0939-1533, DOI: 10.1007/s00419-014-0966-3, Vol.85, No.9, pp.1343-1352, 2015

Abstract:
The paper is devoted to radial and out-of-plane vibration of railway wheels and to wheelset stability as key elements affecting high-speed vehicle dynamics, noise emission, and safety. In the present study, railway wheel tire is treated as a curved beam with various beam models, and the wheel plates are modeled as Winkler’s elastic foundation. New results are presented concerning the influence of the residual stresses on the corrugation and poligonalization of wheels as well as wave propagation in the wheel tire

Keywords:
Elastic wheel, Wheel–rail interaction, Traveling waves, Wheel poligonalization, Corrugation

(20p.)
99.Buczkowski R., Taczała M., Kleiber M., A 16-node locking-free Mindlin plate resting on two-parameter elastic foundation - static and eigenvalue analysis, COMPUTER ASSISTED METHODS IN ENGINEERING AND SCIENCE, ISSN: 2299-3649, Vol.22, pp.99-114, 2015
Buczkowski R., Taczała M., Kleiber M., A 16-node locking-free Mindlin plate resting on two-parameter elastic foundation - static and eigenvalue analysis, COMPUTER ASSISTED METHODS IN ENGINEERING AND SCIENCE, ISSN: 2299-3649, Vol.22, pp.99-114, 2015

Abstract:
The Pasternak elastic foundation model is employed to study the statics and natural frequencies of thick plates in the framework of the finite element method. A new 16-node Mindlin plate element of the Lagrange family and a 32-node zero-thickness interface element representing the response of the foundation are used in the analysis. The plate element avoids ill-conditioned behaviour due to its small thickness. In the case of the eigenvalue analysis, the equation of motion is derived by applying the Hamilton principle involving the variation of the kinetic and potential energy of the plate and foundation. Regarding the plate, the firstorder shear deformation theory is used. By employing the Lobatto numerical integration in which the integration points coincide with the element nodes, we obtain the diagonal form of the mass matrix of the plate. In practice, diagonal mass matrices are often employed due to their very attractive timeintegration schemes in explicit dynamic methods in which the inversion of the effective stiffness matrix as a linear combination of the damping and mass matrices is required. The numerical results of our analysis are verified using thin element based on the classical Kirchhoff theory and 16-node thick plate elements.

Keywords:
Mindlin plate, two-parameter elastic foundation, Lobatto integration, bending and eigenvalue analysis

(14p.)
100.Lumelskyj D., Rojek J., Tkocz M., Numerical simulations of nakazima formability tests with prediction of failure, ROMANIAN JOURNAL OF TECHNICAL SCIENCES - APPLIED MECHANICS, ISSN: 0035-4074, Vol.60, No.3, pp.184-194, 2015
Lumelskyj D., Rojek J., Tkocz M., Numerical simulations of nakazima formability tests with prediction of failure, ROMANIAN JOURNAL OF TECHNICAL SCIENCES - APPLIED MECHANICS, ISSN: 0035-4074, Vol.60, No.3, pp.184-194, 2015

Abstract:
This paper presents results of numerical simulations of the Nakazima test with determination of formability without using the forming limit curve. The onset of localized necking has been determined using the criterion based on analysis of the major principal strain and its first and second time derivatives in the most strained zone. The strain localization has been determined by the maximum of strain acceleration which corresponds to the inflection point of the strain velocity versus time. The limit strains have been determined for different specimens undergoing deformation at different strain paths covering a whole range of the strain paths typical for sheet forming processes. This has allowed us to construct the numerical FLC. The numerical FLC has been compared with the experimental one. It has been shown that the numerical FLC predicts higher formability limits but the differences are not large so the method can be used as a potential alternative tool to determine formability in standard finite element simulations of sheet forming processes.

Keywords:
sheet forming, formability, forming limit curve, numerical simulation

101.Będkowski J., Pelka M., Majek K., Fitri T., Naruniec J., Open source robotic 3D mapping framework with ROS - Robot Operating System, PCL - Point Cloud Library and Cloud Compare, 5TH INTERNATIONAL CONFERENCE ON ELECTRICAL ENGINEERING AND INFORMATICS, 2015-08-10/08-11, Legian-Bali (ID), DOI: 10.1109/ICEEI.2015.7352578, pp.644-649, 2015
Będkowski J., Pelka M., Majek K., Fitri T., Naruniec J., Open source robotic 3D mapping framework with ROS - Robot Operating System, PCL - Point Cloud Library and Cloud Compare, 5TH INTERNATIONAL CONFERENCE ON ELECTRICAL ENGINEERING AND INFORMATICS, 2015-08-10/08-11, Legian-Bali (ID), DOI: 10.1109/ICEEI.2015.7352578, pp.644-649, 2015

Abstract:
We propose an open source robotic 3D mapping framework based on Robot Operating System, Point Cloud Library and Cloud Compare software extended by functionality of importing and exporting datasets. The added value is an integrated solution for robotic 3D mapping and new publicly available datasets (accurate 3D maps with geodetic precision) for evaluation purpose Datasets were gathered by mobile robot in stop scan fashion. Presented results are a variety of tools for working with such datasets, for task such as: preprocessing (filtering, down sampling), data registration (ICP, NDT), graph optimization (ELCH, LUM), tools for validation (comparison of 3D maps and trajectories), performance evaluation (plots of various outputs of algorithms). The tools form a complete pipeline for 3D data processing. We use this framework as a reference methodology in recent work on SLAM algorithms.

Keywords:
Three-dimensional displays, Robot kinematics, Cameras, Mobile communication, Robot sensing systems, XML

102.Musialik P., Majek K., Majek P., Pelka M., Będkowski J., Masłowski A., Typiak A., Accurate 3D mapping and immersive visualization for Search and Rescue, RoMoCo 2015, 10th International Workshop on Robot Motion and Control, 2015-07-06/07-08, Poznań (PL), DOI: 10.1109/RoMoCo.2015.7219728, pp.153-158, 2015
Musialik P., Majek K., Majek P., Pelka M., Będkowski J., Masłowski A., Typiak A., Accurate 3D mapping and immersive visualization for Search and Rescue, RoMoCo 2015, 10th International Workshop on Robot Motion and Control, 2015-07-06/07-08, Poznań (PL), DOI: 10.1109/RoMoCo.2015.7219728, pp.153-158, 2015

Abstract:
This paper concentrates on the topic of gathering, processing and presenting 3D data for use in Search and Rescue operations. The data are gathered by unmanned ground platforms, in form of 3D point clouds. The clouds are matched and transformed into a consistent, highly accurate 3D model. The paper describes the pipeline for such matching based on Iterative Closest Point algorithm supported by loop closing done with LUM method. The pipeline was implemented for parallel computation with Nvidia CUDA, which leads to higher matching accuracy and lower computation time. An analysis of performance for multiple GPUs is presented. The second problem discussed in the paper is immersive visualization of 3d data for search and rescue personnel. Five strategies are discussed: plain 3D point cloud, hypsometry, normal vectors, space descriptors and an approach based on light simulation through the use of NVIDIA OptiX Ray Tracing Engine. The results from each strategy were shown to end users for validation. The paper discusses the feedback given. The results of the research are used in the development of a support module for ICARUS project.

Keywords:
Three-dimensional displays, Data visualization, Graphics processing units, Image color analysis, Computational modeling, Solid modeling, Pipelines

103.Faraj R., Holnicki-Szulc J., Adaptive inertial shock-absorber for vibration damping, ICoEV-2015, ICoEV 2015 : IFTOMM International Conference on Engineering Vibration 2015, 2015-09-07/09-10, Ljubljana (SI), pp.1, 2015
Faraj R., Holnicki-Szulc J., Adaptive inertial shock-absorber for vibration damping, ICoEV-2015, ICoEV 2015 : IFTOMM International Conference on Engineering Vibration 2015, 2015-09-07/09-10, Ljubljana (SI), pp.1, 2015

Keywords:
Adaptive Impact Absorption, shock-absorber, vibration damping

104.Zakrzewska K.E., Samluk A., Pluta K.D., Pijanowska D.G., Evaluation of the effects of antibiotics on cytotoxicity of EGFP and DsRed2 fluorescent proteins used for stable cell labeling, ACTA BIOCHIMICA POLONICA, ISSN: 0001-527X, Vol.61, No.4, pp.809-813, 2014
Zakrzewska K.E., Samluk A., Pluta K.D., Pijanowska D.G., Evaluation of the effects of antibiotics on cytotoxicity of EGFP and DsRed2 fluorescent proteins used for stable cell labeling, ACTA BIOCHIMICA POLONICA, ISSN: 0001-527X, Vol.61, No.4, pp.809-813, 2014

Abstract:
The use of fluorescent markers has proven to be an attractive tool in biological imaging. However, its usefulness may be confined by the cytotoxicity of the fluorescent proteins. In this article, for the first time, we have examined an influence of the antibiotics present in culture medium on cytotoxicity of the EGFP and DsRed2 markers used for whole-cell labeling. Results showed that doxycycline negatively affected albumin synthesis in DsRed2-expressing hepatoma cells, and that both hepatoma cells and human skin fibroblasts, labeled with this protein, were characterized by the lowered growth rates. Thus, the cytotoxic effect of fluorescent markers depends on both protein used for cell labeling and on growth conditions that may cause cell stress.

Keywords:
stable fluorescent labeling, whole-cell labeling, fluorescent protein cytotoxicity

(15p.)
105.Będkowski J., Pełka M., Musialik P., Masłowski A., Multi robot simulator for robot operator training in Tiramisu project, CLAWAR, 17th International Conference on Climbing and Walking Robots, 2014-07-21/07-23, Poznań (PL), pp.575-580, 2014
Będkowski J., Pełka M., Musialik P., Masłowski A., Multi robot simulator for robot operator training in Tiramisu project, CLAWAR, 17th International Conference on Climbing and Walking Robots, 2014-07-21/07-23, Poznań (PL), pp.575-580, 2014

Abstract:
This article concerns current progress in the development of multi robot simulation for TIRAMISU project. This simulator is designed for training of UGV (Unmanned Ground Vehicles) operators in cooperative mission execution. The core components of the system are implemented using VORTEX physics simulation engine with OSG (Open Scene Graph) used for rendering. The engine provides an accurate physics simulation for robots working on a single stage. The main goal during development was to prepare a multi robot architecture for the simulation. The challenge was to integrate all simulation components into a common framework, therefore allowing the robots to interact with each other, without lose of simulation accuracy. Current version of the simulator has two types of robots: a) iRobot-PacBot b)LOCSTRA - a TIRAMISU robot for humanitarian demining. An example of multi robot scenario, transportation of UXO (UneXploded Ordnance), will be discussed.

Keywords:
Humanitarian demining, mobile robot simulation, operator training

106.Majek K., Musialik P., Kaczmarek P., Będkowski J., Lesson Learned from Eurathlon 2013 Land Robot Competition, AUTOMATION 2014, Conference on Automation - Innovations and Future Perspectives, 2014-03-26/03-28, Warszawa (PL), DOI: 10.1007/978-3-319-05353-0_42, No.267, pp.441-451, 2014
Majek K., Musialik P., Kaczmarek P., Będkowski J., Lesson Learned from Eurathlon 2013 Land Robot Competition, AUTOMATION 2014, Conference on Automation - Innovations and Future Perspectives, 2014-03-26/03-28, Warszawa (PL), DOI: 10.1007/978-3-319-05353-0_42, No.267, pp.441-451, 2014

Abstract:
This paper shows evaluation result of the mobile robotic system for Urban Search and Rescue performed during Eurathlon 2013 robotic competition by IAIR-IMM team. Our team was competing in two scenarios: a) Reconnaissance and surveillance in urban structures (USAR), b) Search and rescue in a smoke-filled underground structure. The main task for this system from our team point of view was to build 3D metric map of the environment and to find OPIs (Objects of Potential Interest). Therefore in this paper we described the vision system for objects recognition and 3D map building. The system is composed of mobile robot equipped with camera, 3D laser measurement system and base station composed of computer equipped with NVIDIA GPU for parallel processing of derived clouds of points. The main focus of the work was to improve the performance of the operator controlling the robot in harsh environment. We achieved satisfactory results that could be still improved in many aspects. In experimental part we demonstrated validation of vision recognition system and 3D maps built during preparation trials and during final competition. The best quantitative result of this work was 3rd place in USAR scenario. Unfortunately, we could not build the map in a smoke-filled underground structure, but the result is also very interesting for future developments.

Keywords:
Eurathlon, mobile robot

107.Samluk A., Zakrzewska K.E., Pluta K.D., Generation of Fluorescently Labeled Cell Lines, C3A Hepatoma Cells, and Human Adult Skin Fibroblasts to Study Coculture Models, Artificial Organs, ISSN: 0160-564X, DOI: 10.1111/aor.12064, Vol.37, No.7, pp.E123-E130, 2013
Samluk A., Zakrzewska K.E., Pluta K.D., Generation of Fluorescently Labeled Cell Lines, C3A Hepatoma Cells, and Human Adult Skin Fibroblasts to Study Coculture Models, Artificial Organs, ISSN: 0160-564X, DOI: 10.1111/aor.12064, Vol.37, No.7, pp.E123-E130, 2013

Abstract:
Hepatic/nonhepatic cell cocultures are widely used in studies on the role of homo- and heterotypic interactions in liver physiology and pathophysiology. In this article, for the first time, establishment of the coculture model employing hepatoma C3A cells and human skin fibroblasts, stably expressing fluorescent markers, is described. Suitability of the model in studying coculture conditions using fluorescence microscopy and flow cytometry was examined. C3A cells spontaneously formed island-like growth patterns surrounded by fibroblasts. The “islands” size and resulting intensity of the homo- and heterotypic interactions can easily be tuned by applying various plated cells ratios. We examined the capability of the hepatoma cells to produce albumin in hepatic/nonhepatic cell cocultures. The enzyme-linked immunosorbent assay (ELISA) tests showed that greater number of fibroblasts in coculture, resulting in smaller sizes of hepatoma “islands,” and thus, a larger heterotypic interface, promoted higher albumin synthesis. The use of fluorescently labeled cells in flow cytometry measurements enabled us to separately gate two cell populations and to evaluate protein expression only in/on cells of interest. Flow cytometry confirmed ELISA results indicating the highest albumin production in hepatoma cells cocultured with the greatest number of fibroblasts and the inhibited protein synthesis in coculture with osteosarcoma cells.

Keywords:
C3A fluorescent cell line, Fluorescently labeled fibroblasts, Liver coculture model, Lentiviral vectors, Flow cytometry

(25p.)
108.Bogacz R., Czyczuła W., Pawlak-Burakowska A., Wpływ tłumienia na stateczność strumienia oscylatorów oddziałującego z belką. Stateczność przepływu cieczy, Symulacja w Badaniach i Rozwoju, ISSN: 2081-6154, Vol.3, No.2, pp.71-77, 2012
Bogacz R., Czyczuła W., Pawlak-Burakowska A., Wpływ tłumienia na stateczność strumienia oscylatorów oddziałującego z belką. Stateczność przepływu cieczy, Symulacja w Badaniach i Rozwoju, ISSN: 2081-6154, Vol.3, No.2, pp.71-77, 2012

Abstract:
W niniejszej pracy rozważana jest stateczność ruchu układu złożonego ze strumienia
gęsto rozłożonej masy (oscylatorów) oddziałującego sprężyście lub lepko-sprężyście
z belką na podłożu Winkera (np. modelującej rurę). Układ taki może być uproszczonym
modelem układu pociąg - tor lub modelem rurociągu, przez który przepływa ciecz
(dla uproszczenia nieściśliwa).

Keywords:
stateczność przepływu, ruch względny, tłumienie

(2p.)
109.Lewandowska B., Teoria informacji i jej zastosowania w biologii i w medycynie, XI Krajowe Forum Informacji Naukowej i Technicznej: Człowiek w przestrzeni informacyjnej, 2011-09-20/09-23, Zakopane (PL), pp.1, 2011
Lewandowska B., Teoria informacji i jej zastosowania w biologii i w medycynie, XI Krajowe Forum Informacji Naukowej i Technicznej: Człowiek w przestrzeni informacyjnej, 2011-09-20/09-23, Zakopane (PL), pp.1, 2011

Abstract:
Information theory and its application to the biology and medicine (Abstract). Information theory was founded by Claude E. Shannon in 1948. According to the C. Shannon theory, the information about an event is measured as the probability of the occurrence of the event. The cognitive possibilities which are related to the processes of knowing, understanding and learning something about the phenomenon under study, are employed also in the scientific researches into biology and medicine. A fair stock of information is contained in a living cell of an organism. The structure of an albumen is defined by the information contained in genes. The four-letter DNA language determines the laws governing the twenty-letter language of each albumen. Therefore, a genetitic information may be saved in the form of an one-dimensional instruction. C. Shannon defined mathematically the concept of the decisive information which is the measure of the decision taken on the classification of a sent out sign. In medicine making an exact diagnosis seems to be of key meaning. Proposing a suitable algorithm for generating the diagnosis process we arrive at the objectivity of the process since each illness may be regarded as a message obtained statistically. That is justified by the fact that the defined factors predispose us to some illnesses. In this way it is possible on the base of the theory of information to formalize the process of medical diagnosis.

110.Lewandowska B., Zarządzanie informacją w marketingowo zorientowanej organizacji, VIII Krajowe Forum Informacji Naukowej i Technicznej, 2005-10-12/10-14, Zakopane (PL), pp.26-27, 2005
Lewandowska B., Zarządzanie informacją w marketingowo zorientowanej organizacji, VIII Krajowe Forum Informacji Naukowej i Technicznej, 2005-10-12/10-14, Zakopane (PL), pp.26-27, 2005

Keywords:
zarządzanie informacją, zarządzanie wiedzą, zarządzanie marketingowe

111.Kujawska T., Wójcik J., Nowicki A., Nonlinear pulsed pressure field from focused rectangular apertures: experimental and numerical simulation results, IUS 2005, IEEE International Ultrasonics Symposium, 2005-09-18/09-21, Rotterdam (NL), DOI: 10.1109/ULTSYM.2005.1603267, pp.1992-1995, 2005
Kujawska T., Wójcik J., Nowicki A., Nonlinear pulsed pressure field from focused rectangular apertures: experimental and numerical simulation results, IUS 2005, IEEE International Ultrasonics Symposium, 2005-09-18/09-21, Rotterdam (NL), DOI: 10.1109/ULTSYM.2005.1603267, pp.1992-1995, 2005

Abstract:
The theoretical and experimental studies of the finite amplitude acoustic waves propagation in attenuating media from nonaxisymmetric sources rather rarely can be found in literature in spite of the fact that probes of the rectangular geometry (such as linear phased arrays) are commonly used in clinical practice for medical ultrasonic imaging purposes. The main reason of such situation is a lack in simpler theoretical models and in computationally efficient numerical algorithms that are able to predict accurately the nonlinear effects in 4D ultrasound fields from pulsed, arbitrarily shaped sources (plane and focused) in biological media with arbitrary frequency-dependent absorption. In recent years the only study describing the computationally efficient numerical model that is able to simulate accurately the 4D nonlinear ultrasound field in water and in biological tissues from pulsed nonaxisymmetric sources was developed by Zemp et al. [1]. Their model is based on the second order operator-splitting method, proposed by Tavakkoli et al., with the modified fractional step scheme whereby the combined effects of diffraction and absorption are accounted for over half-steps and the effects of nonlinear harmonic interactions over full incremental steps. The computation of diffraction and absorption sub-steps was based on the angular spectrum technique with modified sampling method (to obtain computational savings due to larger axial propagation steps) while the computation of nonlinear steps was based on the time-domain solution to Burgers' equation. There are not reports yet describing an experimental confirmation of an agreement between the simulated nonlinear acoustic pulsed fields in water or in soft tissues from nonaxisymmetric focused sources (obtained by using the numerical model proposed) and nonlinear field from realistic probes.

Keywords:
Apertures, Numerical simulation, Acoustic pulses, Absorption, Ultrasonic imaging, Computational modeling, Acoustic propagation, Focusing, Phased arrays, Nonlinear acoustics

112.Nowicki A., Wójcik J., Secomski W., Multitone nonlinear coding, IUS 2005, IEEE International Ultrasonics Symposium, 2005-09-18/09-21, Rotterdam (NL), DOI: 10.1109/ULTSYM.2005.1603121, pp.1420-1423, 2005
Nowicki A., Wójcik J., Secomski W., Multitone nonlinear coding, IUS 2005, IEEE International Ultrasonics Symposium, 2005-09-18/09-21, Rotterdam (NL), DOI: 10.1109/ULTSYM.2005.1603121, pp.1420-1423, 2005

Abstract:
Tissue Harmonic Imaging (THI) was introduced in 1997 [1] and is today routinely used in diagnostic ultrasound. The benefits of harmonic imaging in many clinical situations have been proved. However, it has to be stressed that it is away from optimal because only half of the available transducer bandwidth is used for image formation - lower half for transmission and upper half during reception.

Keywords:
Ultrasonic imaging, Image resolution, Polarization, Absorption, Image coding, Pulse inverters, Dynamic range, Nonlinear equations, Boundary conditions, Propagation losses

113.Hoffman J., Szymański Z., Time-dependent spectroscopy of plasma plume under laser welding conditions, JOURNAL OF PHYSICS D-APPLIED PHYSICS, ISSN: 0022-3727, DOI: 10.1088/0022-3727/37/13/010, Vol.37, pp.1792-1799, 2004
Hoffman J., Szymański Z., Time-dependent spectroscopy of plasma plume under laser welding conditions, JOURNAL OF PHYSICS D-APPLIED PHYSICS, ISSN: 0022-3727, DOI: 10.1088/0022-3727/37/13/010, Vol.37, pp.1792-1799, 2004

Abstract:
Momentary emission spectra of iron and argon lines were measured in a plasma plume induced during welding with a continuous wave CO2 laser. Time-dependent spectra were registered using a fast gate, lens coupled microchannel plate image intensifier placed between a spectrograph and a 1254 silicon intensified target detector connected to an optical multichannel analyser. The results, together with the analysis of the colour images from a fast camera, show that in the case when argon is the shielding gas, two plasmas exist: the argon plasma and the iron plasma. It has been found that during strong bursts the plasma plume over the keyhole consists mainly of metal vapour, not being diluted by the shielding gas. No apparent mixing of the metal vapour and the shielding gas has been observed. The space-averaged electron densities determined from the Stark broadening of the 7503.87, 7514.65 Å Ar I lines amounts to (0.75–1.05) × 1023 m−3 depending on the distance from the surface. Assuming that argon is not mixed with the metal vapour and is in local thermodynamic equilibrium these electron densities correspond to the temperatures of 12–13 kK. At the peaks of strong vapour bursts the space-averaged electron densities determined from the Stark broadening of the 5383.37 Å Fe I line are (0.6–1) × 1023 m−3. Numerical simulations showed that the maximum densities in the plasma centre are considerably higher and amount to ~1.8 × 1023 m−3 and ~2.45 × 1023 m−3 in the case of the argon and metal plasma, respectively. Consequently the absorption of the laser beam in the plasma plume amounts to ~5% of the beam power in the case of argon and 10% in the case of metal plasma.

(32p.)
114.Kujawska T., Wójcik J., Filipczyński L., Possible Temperature Effects Computed for Acoustic Microscopy Used For Living Cells, ULTRASOUND IN MEDICINE AND BIOLOGY, ISSN: 0301-5629, DOI: 0.1016/j.ultrasmedbio.2003.08.018, Vol.30, No.1, pp.93-101, 2004
Kujawska T., Wójcik J., Filipczyński L., Possible Temperature Effects Computed for Acoustic Microscopy Used For Living Cells, ULTRASOUND IN MEDICINE AND BIOLOGY, ISSN: 0301-5629, DOI: 0.1016/j.ultrasmedbio.2003.08.018, Vol.30, No.1, pp.93-101, 2004

Abstract:
Imaging of living cells or tissues at a microscopic resolution, where GHz frequencies are used, provides a foundation for many new biological applications. The possible temperature increase causing a destructive influence on the living cells should be then avoided. However, there is no information on possible local temperature increases at these very high frequencies where, due to strongly focused ultrasonic beams, nonlinear propagation effects occur. Acoustic parameters of living cells were assumed to be close to those of water; therefore, the power density of heat sources in a water medium was determined as a basic quantity. Hence, the numerical solution of temperature distributions at the frequency of 1 GHz was computed for high and low powers generated by the transducer equal to 0.32 W and 0.002 W. In the first case, typical nonlinear propagation effects were demonstrated and, in the second one, propagation was almost linear. The focal temperature increase obtained in water equaled 14°C for the highest possible theoretical repetition frequency of fr = 10 MHz and for the thermal insulation at the sapphire lens-water boundary. Simultaneously, the scanning velocity of the tested object was assumed to be incomparably low in respect to the acoustic beam velocity. The maximum temperature increase in water occurred exactly at this boundary, being equal there to 20°C. It was shown that, first of all, the very high absorption of water was significant for the temperature distribution in the investigated region, suppressing the focal temperature peaks. Because the temperature increases are proportional to the repetition frequency, so for example, at its practical value of fr = 0.1 MHz, all temperature increases will be 100 times lower than listed above. For the low transducer power of 0.002 W, the corresponding temperature increases were about 140 times lower than those for the high power of 0.32 W. The presented solutions are devoted mainly to the reflection pulse mode; however, they can be also applied for the transmitting (continuous-wave) mode, as shown in an example. Pressure distributions were computed for the acoustic field of the microscope for the first and higher harmonics. Hence, at the frequency of 1 GHz, the effective focal radius in water measured as the −6-dB amplitude pressure drop was found to be 1,1 μm, and 0.7 μm for the second harmonic, independently of the assumed transducer power. So the width of the beam, scanning the living cells in the focal region, was equal to 2.2 μm at the fundamental frequency of 1 GHz.

Keywords:
Temperature, Acoustic microscopy, Living cells, Temperature increase, Pressure

(32p.)
115.Radulescu E.G., Lewin P.A., Wójcik J., Nowicki A., Berger W.A., The influence of finite aperture and frequency response of ultrasonic hydrophone probes On the determination of acoustic output, Ultrasonics, ISSN: 0041-624X, DOI: 10.1016/j.ultras.2003.11.019, Vol.42, No.1-9, pp.367-372, 2004
Radulescu E.G., Lewin P.A., Wójcik J., Nowicki A., Berger W.A., The influence of finite aperture and frequency response of ultrasonic hydrophone probes On the determination of acoustic output, Ultrasonics, ISSN: 0041-624X, DOI: 10.1016/j.ultras.2003.11.019, Vol.42, No.1-9, pp.367-372, 2004

Abstract:
The influence of finite aperture and frequency response of piezoelectric ultrasonic hydrophone probes on the Thermal and Mechanical Indices was investigated using a comprehensive acoustic wave propagation model. The experimental verification of the model was obtained using a commercially available, 8 MHz, dynamically focused linear array and a single element, 5 MHz, focused rectangular source. The pressure–time waveforms were recorded using piezoelectric polymer hydrophone probes of different active element diameters and bandwidths. The nominal diameters of the probes ranged from 50 to 500 μm and their usable bandwidths varied between 55 and 100 MHz. The Pulse Intensity Integral (PII), used to calculate the Thermal Index (TI), was found to increase with increasing bandwidth and decreasing effective aperture of the probes. The Mechanical Index (MI), another safety indicator, was also affected, but to a lesser extent. The corrections needed were predicted using the model and successfully reduced the discrepancy as large as 30% in the determination of PII. The results of this work indicate that by accounting for hydrophones' finite aperture and correcting the value of PII, all intensities derived from the PII can be corrected for spatial averaging error. The results also point out that a caution should be exercised when comparing acoustic output data. In particular, hydrophone's frequency characteristics of the effective diameter and sensitivity are needed to correctly determine the MI, TI, and the total acoustic output power produced by an imaging transducer.

Keywords:
Ultrasound imaging, Nonlinear propagation, Spatial averaging, Safety indices

(27p.)
116.Lewandowska B., Konferencja naukowa "Etyka środowiskowa jako wyzwanie XXI wieku": Warszawa, 20 kwietnia 2002 r., Studia Ecologiae et Bioethicae, ISSN: 1733-1218, Vol.2, pp.811-818, 2004
Lewandowska B., Konferencja naukowa "Etyka środowiskowa jako wyzwanie XXI wieku": Warszawa, 20 kwietnia 2002 r., Studia Ecologiae et Bioethicae, ISSN: 1733-1218, Vol.2, pp.811-818, 2004

Keywords:
etyka środowiskowa

117.Radulescu E., Lewin P.A., Wójcik J., Nowicki A., Calibration of Ultrasonic Hydrophone Probes up to 100 MHz using Time Gating Frequency Analysis and Finite Amplitude Wave, Ultrasonics, ISSN: 0041-624X, DOI: 10.1016/S0041-624X(03)00123-9, Vol.41, No.4, pp.247-254, 2003
Radulescu E., Lewin P.A., Wójcik J., Nowicki A., Calibration of Ultrasonic Hydrophone Probes up to 100 MHz using Time Gating Frequency Analysis and Finite Amplitude Wave, Ultrasonics, ISSN: 0041-624X, DOI: 10.1016/S0041-624X(03)00123-9, Vol.41, No.4, pp.247-254, 2003

Abstract:
A number of ultrasound imaging systems employs harmonic imaging to optimize the trade off between resolution and penetration depth and center frequencies as high as 15 MHz are now used in clinical practice. However, currently available measurement tools are not fully adequate to characterize the acoustic output of such nonlinear systems primarily due to the limited knowledge of the frequency responses beyond 20 MHz of the available piezoelectric hydrophone probes. In addition, ultrasound hydrophone probes need to be calibrated to eight times the center frequency of the imaging transducer. Time delay spectrometry (TDS) is capable of providing transduction factor of the probes beyond 20 MHz, however its use is in practice limited to 40 MHz. This paper describes a novel approach termed time gating frequency analysis (TGFA) that provides the transduction factor of the hydrophone probes in the frequency domain and significantly extends the quasi-continuous calibration of the probes up to 60 MHz. The verification of the TGFA data was performed using TDS calibration technique (up to 40 MHz) and a nonlinear calibration method (up to 100 MHz). The nonlinear technique was based on a novel wave propagation model capable of predicting the true pressure–time waveforms at virtually any point in the field. The spatial averaging effects introduced by the finite aperture hydrophones were also accounted for. TGFA calibration results were obtained for different PVDF probes, including needle and membrane designs with nominal diameters from 50 to 500 μm. The results were compared with discrete calibration data obtained from an independent national laboratory and the overall uncertainty was determined to be ±1.5 dB in the frequency range 40–60 MHz and less than ±1 dB below 40 MHz.

Keywords:
Time gating frequency analysis (TGFA), Time delay spectrometry (TDS), High frequency hydrophone calibration, Nonlinear hydrophone calibration, High frequency ultrasound, Ultrasonic metrology

(27p.)
118.Radulescu E., Wójcik J., Lewin P.A., Nowicki A., Nonlinear Propagation Model for Ultrasound Hydrophones Calibration in Frequency Range up to 100 MHz, Ultrasonics, ISSN: 0041-624X, DOI: 10.1016/S0041-624X(03)00124-0, Vol.41, No.4, pp.239-245, 2003
Radulescu E., Wójcik J., Lewin P.A., Nowicki A., Nonlinear Propagation Model for Ultrasound Hydrophones Calibration in Frequency Range up to 100 MHz, Ultrasonics, ISSN: 0041-624X, DOI: 10.1016/S0041-624X(03)00124-0, Vol.41, No.4, pp.239-245, 2003

Abstract:
To facilitate the implementation and verification of the new ultrasound hydrophone calibration techniques described in the companion paper (somewhere in this issue) a nonlinear propagation model was developed. A brief outline of the theoretical considerations is presented and the model’s advantages and disadvantages are discussed. The results of simulations yielding spatial and temporal acoustic pressure amplitude are also presented and compared with those obtained using KZK and Field II models. Excellent agreement between all models is evidenced. The applicability of the model in discrete wideband calibration of hydrophones is documented in the companion paper somewhere in this volume.

Keywords:
Nonlinear propagation modeling, Nonlinear propagation, JW model

(27p.)
119.Radulescu E.G., Wójcik J., Lewin P.A., Nowicki A., A Novel Method for Characterization of Nonlinear Propagation and Spatial Averaging Effects for Ultrasound Imaging Systems, 2002 IEEE Ultraasonic Symposium, 2002-10-08/10-11, Monachium (DE), DOI: 10.1109/ULTSYM.2002.1192498, pp.1153-1156, 2002
Radulescu E.G., Wójcik J., Lewin P.A., Nowicki A., A Novel Method for Characterization of Nonlinear Propagation and Spatial Averaging Effects for Ultrasound Imaging Systems, 2002 IEEE Ultraasonic Symposium, 2002-10-08/10-11, Monachium (DE), DOI: 10.1109/ULTSYM.2002.1192498, pp.1153-1156, 2002

Abstract:
Harmonic imaging at frequencies up to 15 MHz is now routinely used in clinical practice and frequencies well beyond 20 MHz are considered for diagnostic ultrasound imaging applications. However, currently available measurement tools are not fully adequate to characterize such high frequency systems, primarily due to the combined effects of limited frequency responses and spatial averaging effects. To alleviate this problems, a comprehensive wave propagation model has been developed and tested. The model can predict the linear and nonlinear acoustic wave propagation generated by differently shaped acoustic radiators at virtually any point in the field and takes into account spatial averaging effects introduced by hydrophone probes and their associated frequency responses. The applicability of the model in hydrophone probe calibration up to 100 MHz is demonstrated. Also, a novel calibration technique termed Time-Gating Frequency Analysis (TGFA) is briefly described and calibration results in the frequency range up to 60 MHz for hydrophones having effective diameters between 150 and 500 /spl mu/m are presented. Also presented are the results of the investigation that determined the effect of using hydrophone probes of different diameters and bandwidth on Spatial-Peak Pulse-Average Intensity (I/sub SPPA/). It was found that the values of I/sub SPPA/ increased with decreasing effective aperture of the hydrophone probe and its bandwidth.

Keywords:
Ultrasonic imaging, Frequency, Sonar equipment, Probes, Calibration, Acoustic propagation, Nonlinear acoustics, Bandwidth, Acoustic measurements, Current measurement

120.Szymański Z., Hoffman J., Kurzyna J., Plasma plume oscillations during welding of thin metal sheets with a CW CO2 laser, JOURNAL OF PHYSICS D-APPLIED PHYSICS, ISSN: 0022-3727, Vol.34, pp.189-199, 2001
Szymański Z., Hoffman J., Kurzyna J., Plasma plume oscillations during welding of thin metal sheets with a CW CO2 laser, JOURNAL OF PHYSICS D-APPLIED PHYSICS, ISSN: 0022-3727, Vol.34, pp.189-199, 2001

Abstract:
An analysis is presented of the oscillations of keyhole pressure and plasma radiation emitted during welding with a continuous wave (CW) CO2 laser. Welding was done with a CW CO2 laser, Photon Sources VFA 2500, operating at the power of 1.75 kW. The welded materials were mild and stainless steel sheets, 0.8–2 mm thick. The shielding gas was argon or helium. Oscillations of plasma radiation were registered in monochromatic or broad band radiation with the use of a photomultiplier or photodiode and pressure variations with a microphone in the frequency range of 20–2 × 104 Hz. It has been found that the optical signal from the plasma plume is closely connected with the acoustic signal and that the source of the acoustic signal is the pulsating movement of the plasma plume. Spectral analysis of the measured oscillations shows differences in power spectra depending on the welding conditions. Generally, two intrinsic frequency peaks in the range of 0.5–4 kHz are always present but the amplitude, frequency and width of the peaks depend on the material and welding conditions. The results show that the optical and acoustic signals emitted during the welding process can be useful for process monitoring. The behaviour of the observed oscillations is characteristic for deterministic chaos. Considerable regularization of the process was observed as an effect of modulation of the laser beam. The modulation factor (Pmax−Pmin)/Pmax was equal to 0.2 and the modulation frequency was 2 kHz. In this case, the intense peak corresponding to the modulation frequency was observed in the power spectrum together with smaller peaks corresponding to the harmonic frequencies.

(32p.)
121.Filipczyński L., Wójcik J., Kujawska T., Łypacewicz G., Tymkiewicz R., Zienkiewicz B., Nonlinear Native Propagation Effect of Diagnostic Ultrasound Computed and Measured in Blood, ULTRASOUND IN MEDICINE AND BIOLOGY, ISSN: 0301-5629, DOI: 10.1016/S0301-5629(00)00329-X, Vol.27, No.2, pp.251-257, 2001
Filipczyński L., Wójcik J., Kujawska T., Łypacewicz G., Tymkiewicz R., Zienkiewicz B., Nonlinear Native Propagation Effect of Diagnostic Ultrasound Computed and Measured in Blood, ULTRASOUND IN MEDICINE AND BIOLOGY, ISSN: 0301-5629, DOI: 10.1016/S0301-5629(00)00329-X, Vol.27, No.2, pp.251-257, 2001

Abstract:
Nonlinear propagation effects produced by focused pulses in blood were measured over a 20-cm range, being inspired by diagnostic applications in cardiology. The initial and maximum pressures applied during measurements in blood were equal to 0.40 MPapp and 0.76 MPapp, while the pressure estimated at the patient body surface equalled 0.70 MPapp. Measurements of the frequency characteristic and the linearity of the ultrasonic probe used in experiments were performed in water. A numerical procedure developed previously was applied in blood to calculate the pressure distribution of its first and second harmonics along the beam axis. The comparison of numerical and measured distributions in blood at a temperature of 37°C showed rather good agreement. Using numerical methods, a proportional growth of the second harmonic with the increased applied initial pressure was first observed, and finally the maximum limiting effect was found. In this way, much higher level of harmonics could be obtained. However, there arise the questions of the transmitting system construction and of the nonuniform resolution in the case of harmonic imaging when increasing the applied initial pressure.

Keywords:
Ultrasound, Pulses, Nonlinear propagation, Blood, Cardiology

(32p.)
122.Wójcik J., Filipczyński J., Kujawska J., Temperature elevations computed for three-layer and four-layer obstetrical tissue model in nonlinear and linear ultrasonic propagation cases, ULTRASOUND IN MEDICINE AND BIOLOGY, ISSN: 0301-5629, DOI: 10.1016/S0301-5629(98)00144-6, Vol.25, No.2, pp.259-267, 1999
Wójcik J., Filipczyński J., Kujawska J., Temperature elevations computed for three-layer and four-layer obstetrical tissue model in nonlinear and linear ultrasonic propagation cases, ULTRASOUND IN MEDICINE AND BIOLOGY, ISSN: 0301-5629, DOI: 10.1016/S0301-5629(98)00144-6, Vol.25, No.2, pp.259-267, 1999

Abstract:
The authors computed temperature elevations in a three-layer and a four-layer tissue model, assuming the crucial obstetrical case when the ultrasonic pulse propagating through the abdomiinal wall and the fluid-filled bladder penetrates into soft fetal tissues.To consider nonlinear propagation, the authors applied a new theory of nonlinear increase of absorption recently developed by the first author. Computations were carried out for pulses with a carrier frequency of 3 MHz, duration time of 1.33 μs, and pulse repetition frequency of 3.3 kHz. Similar computations were carried out for a four-layer tissue model corresponding to the third trimester of gestation. The ceramic piezoelectric transducer 2 cm in diameter radiated the ultrasonic beam focused at a distance of 6.5 cm. The intensities at the radiating transducer (at the source) were ISAPA= 10 and 5 W/cm2. Temperature elevations and distributions were determined numerically for various values of low-amplitude absorption coefficients assumed to be the same as attenuation coefficients. It was shown in the three-layer tissue model that the maximum temperature elevation can be about 50% higher for nonlinear than for linear propagation.The maximum fetal temperature elevation in this case was 2.36°C for nonlinear and 1.84°C for linear propagation. The temperature elevation in the abdominal wall was lower than those temperatures when the attenuation of the abdominal wall was assumed to be a low value of 0.05 Np/cm.MHz (0.45 dB/cm.MHz). However, when it was increased to 0.16 Np/cm.MHz (1.4 dB/cm.MHz), the temperature elevation of the abdominal wall reached 3.2°C and the maximum fetal elevation was 1.65°C. In such cases, the abdominal wall became the principal source of heat production. In this case, the difference between fetal temperature elevations for nonlinear and linear propagation was only about 10%. The results obtained in the four-layer tissue model, in which the uterus tissue also was represented, show that temperature elevations in this case are about 3.6 times lower than in the three-layer tissue model, with comparable attenuation of the abdominal wall. Differences between nonlinear and linear propagation in the four-layer tissue model are negligible. The temperature elevations obtained were proportional to the pulse repetition frequency, without changing temperature distributions in the ultrasonic beam. In this manner, fetal temperature elevations can be reduced by reducing the repetition frequency.

Keywords:
Ultrasound, Nonlinear propagation, Temperature, Obstetrics

(32p.)
123.Filipczyński L., Kujawska T., Tymkiewicz R., Wójcik J., Nonlinear and linear propagation of diagnostic ultrasound pulses, ULTRASOUND IN MEDICINE AND BIOLOGY, ISSN: 0301-5629, DOI: 10.1016/S0301-5629(98)00174-4, Vol.25, No.2, pp.285-299, 1999
Filipczyński L., Kujawska T., Tymkiewicz R., Wójcik J., Nonlinear and linear propagation of diagnostic ultrasound pulses, ULTRASOUND IN MEDICINE AND BIOLOGY, ISSN: 0301-5629, DOI: 10.1016/S0301-5629(98)00174-4, Vol.25, No.2, pp.285-299, 1999

Abstract:
The effect of nonlinear propagation in fluid followed by soft tissue was studied both theoretically and experimentally for a most crucial case in obstetrical ultrasonography. For this purpose, short pressure pulses, with the duration time of 1.3 μs and a carrier frequency of 3 MHz, radiated by a concave transducer into water, with maximum intensities up to the value of 18 W/cm2, were computed and measured. The ultrasonic beam had the physical focus at the distance of 6.5 cm, where the highest focal intensity of ISPPA= 242 W/cm2 was obtained. In front of the transducer, at a distance of 7 cm, artificial tissue samples prepared on the basis of ground porcine kidney, with a thickness of 0.5, 1.5 and 3 cm, were placed in water. Pressure pulses and their spectral components were produced numerically and measured by means of a PVDF hydrophone in water before and after penetrating the tissue samples. The theoretical analysis and measurements were carried out, in every case, for two signal levels: for a high level assuring nonlinear propagation and for a low one where conditions of linear propagation were fulfilled. In this way, it was possible to compare directly the effects of nonlinear and linear propagation, in every case showing a good conformity of theoretical values with measured ones. A method of determination of the effective frequency response of the hydrophone was elaborated to enable quantitative comparisons of numerical and experimental results. The theoretical part of our study was based on a paper of Wójcik (1998), enabling us to compute the characteristic function of nonlinear increase of absorption. An agreement of up to 10% was obtained when comparing theoretical and measured values of these functions in the investigated beam in water and behind tissue samples. The results obtained showed that the recently given theory of nonlinear absorption, based on the spectral analysis and the elaborated numerical procedures, may be useful in various practical ultrasonic medical problems and also in technological applications.

Keywords:
Ultrasound, Pulses, Nonlinear propagation, Diagnostics

(32p.)
124.Wójcik J., Conservation of energy and absorption in acoustic fields for linear and nonlinear propagation, JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA, ISSN: 0001-4966, DOI: 10.1121/1.423849, Vol.104, No.5, pp.2654-2663, 1998
Wójcik J., Conservation of energy and absorption in acoustic fields for linear and nonlinear propagation, JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA, ISSN: 0001-4966, DOI: 10.1121/1.423849, Vol.104, No.5, pp.2654-2663, 1998

Abstract:
In the present paper, the energy effects accompanying a strong sound disturbance of a medium are analyzed. The waves may be, in time, periodic — continuous or pulsed — or have the form of single pulses. The description is based on equations which are commonly applied in nonlinear acoustics. The Fourier analysis, elements of the theory of linear operators, and analytical functions are applied. A general method is given for the construction of the absorption operator in the domain of space–time coordinates (x,t), to which the small-signal absorption coefficient corresponds. By analogy to linear equations and the corresponding dispersions equations, the quasi-dispersion equations in the case of nonlinear description are introduced. Simplification of the “classical” equation of nonlinear acoustics was performed. The relations between absorption operators in the space and time domains are shown. It is demonstrated that in nonlinear interactions, where terms of such type — nonlinear function of pressure — dominate, the power (energy) of the disturbance is conserved. Just as in the linear notation, the only reason why the total power (energy) changes is linear absorption, but that one which occurs under the conditions of nonlinear propagation. In consequence, the equations of power (and energy) balancing the disturbance have the same formal shape in nonlinear and linear descriptions. The equations provide a theoretical basis for different, easier, and more accurate methods than those used previously for determination (numerical and experimental) of, e.g., the power density of heat sources generated by sound. The function of the nonlinear gain of absorption and the function of effective absorption were also introduced. On the basis of quasi-dispersion equations the phenomenon of overtone generation (not harmonics) is shortly discussed.

Keywords:
Acoustic absorption, Acoustics, Nonlinear acoustics, Absorption coefficient, Acoustic analysis

(32p.)
125.Nowicki A., Secomski W., Wójcik J., Acoustic streaming: Comparison of low amplitude linear model with streaming velocities measured by means of 32 MHz doppler, ULTRASOUND IN MEDICINE AND BIOLOGY, ISSN: 0301-5629, DOI: 10.1016/S0301-5629(97)00005-7, Vol.23, No.5, pp.783-791, 1997
Nowicki A., Secomski W., Wójcik J., Acoustic streaming: Comparison of low amplitude linear model with streaming velocities measured by means of 32 MHz doppler, ULTRASOUND IN MEDICINE AND BIOLOGY, ISSN: 0301-5629, DOI: 10.1016/S0301-5629(97)00005-7, Vol.23, No.5, pp.783-791, 1997

Abstract:
The pressure gradient along the ultrasonic beam results in medium streaming. Following Nyborg's analysis of the Navier-Stokes equation, Wu and Du developed an approximate solution for the streaming velocity generated by flat and weakly focused transducers. We have modified their solution of the Poisson equation by directly deriving the Dirichlet boundary conditions to be applied for this type of equation. Our numerical results (for the linear case) were about one half smaller for flat and weakly focused Gaussian beam transducers compared to the results by Wu and Du. The theoretical calculations were verified using a purpose-designed 32-MHz pulsed Doppler unit. The applied average acoustic power was changed from 1 μW to 6 mW, the burst width was 0.5 μs and the pulse repetition frequency was 32 kHz. The experiments were done on 4-mm-diameter flat and focused (focal distance = 8 and 12 mm) transducers. The streaming was measured along the ultrasonic beam from 0–20 mm; at all positions, the maximum Doppler frequency was estimated from the recorded spectra. Streaming was induced in a solution of water and corn starch. The experimental results showed that, for a given acoustic power, the streaming velocity was independent of the starch density in water changed from 0.3–40 g of starch in 1 l of distilled water. For applied acoustic powers, the streaming velocity changed linearly from 0.2–40 mm/s. Both the theoretical solutions for plane and focused waves and the experimental results were in good agreement.

Keywords:
Ultrasound, Streaming, Nonlinear ultrasound effects, Doppler

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126.Filipczyński L., Kujawska T., Tymkiewicz R., Wójcik J., Amplitude, isobar and gray -scale imaging of ultrasonic shadows behind rigid, elastic and gaseous spheres, ULTRASOUND IN MEDICINE AND BIOLOGY, ISSN: 0301-5629, DOI: 10.1016/0301-5629(95)02031-4, Vol.22, No.2, pp.261-270, 1996
Filipczyński L., Kujawska T., Tymkiewicz R., Wójcik J., Amplitude, isobar and gray -scale imaging of ultrasonic shadows behind rigid, elastic and gaseous spheres, ULTRASOUND IN MEDICINE AND BIOLOGY, ISSN: 0301-5629, DOI: 10.1016/0301-5629(95)02031-4, Vol.22, No.2, pp.261-270, 1996

Abstract:
The theory of wave reflection from spherical obstacles was applied for determination of the cause of the shadow created by plane wave pulses incident on rigid, steel, gaseous spheres and on spheres made of kidney stones. The spheres were immersed in water which was assumed to be a tissuelike medium. Acoustic pressure distributions behind the spheres with the radii of 1 mm, 2.5 mm and 3.5 mm were determined at the frequency of 5 MHz. The use of the exact wave theory enabled us to take into account the diffraction effects. The computed pressure distributions were verified experimentally at the frequency of 5 MHz for a steel sphere with a 2.5-mm radius. The experimental and theoretical pulses were composed of about three ultrasonic frequency periods. Acoustic pressure distributions in the shadow zone of all spheres were shown in the amplitude axonometric projection, in the grey scale and also as acoustic isobar patterns. Our analysis confirmed existing simpler descriptions of the shadow from the point of view of reflection and refraction effects; however, our approach is more general, also including diffraction effects and assuming the pulse mode. The analysis has shown that gaseous spherical inclusions caused shadows with very high dynamics of acoustic pressures that were about 15 dB higher in relation to all the other spheres. The shadow length, determined as the length at which one observes a 6-dB drop of the acoustic pressure, followed the relation r−6dB = 3.7a2λ with the accuracy of about 20% independent of the sphere type. λ denotes the wavelength and a the sphere radius. Thus, a theoretical possibility of differentiating between gaseous and other inclusions and of estimation of the inclusion size in the millimeter range from the shadow was shown. The influence of the frequency-dependent attenuation on the shadow will be considered in the next study.

Keywords:
Shadow, Pulses, Spheres, Ultrasonography

(32p.)
127.Nowicki A., Secomski W., Wójcik J., 32 MHz Doppler assessment for streaming measurements, 1996 IEEE Ultrasonics Symposium, 1996-11-03/11-06, San Antonio, Texas (US), DOI: 10.1109/ULTSYM.1996.584158, pp.995-998, 1996
Nowicki A., Secomski W., Wójcik J., 32 MHz Doppler assessment for streaming measurements, 1996 IEEE Ultrasonics Symposium, 1996-11-03/11-06, San Antonio, Texas (US), DOI: 10.1109/ULTSYM.1996.584158, pp.995-998, 1996

Abstract:
An approximate solution for the streaming velocity generated by flat and weakly focused transducers was derived by directly solving the Dirichlet boundary conditions for the Poisson equation. The theoretical calculations were verified using a purpose-designed 32 MHz pulsed Doppler unit. The applied average acoustic power was changed from 1 /spl mu/W to 6 mW. The experiments were done on 4 mm diameter flat and focused transducers. The streaming velocity was measured along the ultrasonic beam from O to 20 mm. Streaming was induced in a solution of water and corn starch. The experimental results showed that for a given acoustic power the streaming velocity was independent of the starch density in water changed from 0.3 grams to 40 grams of starch in 1 litre of distilled water. For applied acoustic powers, the streaming velocity changed linearly from 0.2 to 40 mm/s. Theoretical solutions for both plane and focused waves agreed with experimental results.

Keywords:
Acoustic beams, Poisson equations, Acoustic transducers, Ultrasonic transducers, Differential equations, Ultrasonic variables measurement, Acoustic waves, Impedance, Navier-Stokes equations, Boundary conditions

128.Filipczyński L., Kujawska T., Wójcik J., Temperature elevation in focused Gaussian ultrasonic beams at various insonation times, ULTRASOUND IN MEDICINE AND BIOLOGY, ISSN: 0301-5629, DOI: 10.1016/0301-5629(93)90073-W, Vol.19, No.8, pp.667-679, 1993
Filipczyński L., Kujawska T., Wójcik J., Temperature elevation in focused Gaussian ultrasonic beams at various insonation times, ULTRASOUND IN MEDICINE AND BIOLOGY, ISSN: 0301-5629, DOI: 10.1016/0301-5629(93)90073-W, Vol.19, No.8, pp.667-679, 1993

Abstract:
Transient solution of the thermal conductivity equation for the three-dimensional case of the Gaussian ultrasonic focused beam was derived and applied for cases relevant to medical ultrasonography. Quantitative results for the case of a homogeneous medium with constant values of thermal coefficients and constant absorption as well as for the two-layer tissue model used in obstetrics were presented for various diagnostic probes used in ultrasonography. The possible effects of perfusion and nonlinear propagation were neglected. The results obtained are in agreement with results of other authors when considering the steady-state and the infinitely short insonation time. The computations show the influence of the insonation time on the temperature elevation, thus making it possible to introduce its value as a factor in limiting the possible harmful effects in ultrasonography. This has been shown in diagrams presenting the temperature distribution along the beam axis of 6 different diagnostic probes for various insonation times and demonstrating the corresponding temperature decrease when limiting the insonation time to 5 and 1 min. For instance, the highest temperature elevation (for probe number 1, see Table 1) decreases 2.6 and 5 times with respect to the steady-state temperature when the insonation time equals 5 and 1 min, respectively.

Keywords:
Temperature, Ultrasonography, Time, Hazard

(32p.)
129.Filipczyński L., Wójcik J., Estimation of transient temperature elevation in lithotripsy and in ultrasonography, ULTRASOUND IN MEDICINE AND BIOLOGY, ISSN: 0301-5629, DOI: 10.1016/0301-5629(91)90104-5, Vol.17, No.7, pp.715-721, 1991
Filipczyński L., Wójcik J., Estimation of transient temperature elevation in lithotripsy and in ultrasonography, ULTRASOUND IN MEDICINE AND BIOLOGY, ISSN: 0301-5629, DOI: 10.1016/0301-5629(91)90104-5, Vol.17, No.7, pp.715-721, 1991

Abstract:
Transient solutions of the thermal conductivity equation for the two-dimensional case of an elongated cylíndrical focus in the ultrasonic beam were derived and applied for lithotripsy and obstetrical ultrasonography. Assuming uniform and Gaussian distributions in the focus of the beam cross section, it was possible to estimate the temperature elevation arising in lithotripsy for various repetition frequencies of shock-wave pulses and for various radii of the beam. In obstetrical ultrasonography where the blood perfusion is difficult to determine, the authors suggested that the insonation time be used as the decisive factor for the temperature determination. Values of focal intensities were found necessary to increase the tissue temperature by 1°C as a function of the insonation time and the beam radius which exclude the possibility of any hazardous effect caused by temperature elevation.

Keywords:
Lithotripsy, Obstetrics, Ultrasonography, Temperature, Hazard

(32p.)