Publications reported by three months

1.Kukla D., Szwed M., Roskosz M., Ocena grubości warstw chromowych na stali i staliwie z wykorzystaniem metody prądów wirowych, PRZEGLĄD SPAWALNICTWA, ISSN: 0033-2364, Vol.89, No.11, pp.2017-1, 6
Kukla D., Szwed M., Roskosz M., Ocena grubości warstw chromowych na stali i staliwie z wykorzystaniem metody prądów wirowych, PRZEGLĄD SPAWALNICTWA, ISSN: 0033-2364, Vol.89, No.11, pp.2017-1, 6

Abstract:
W ramach niniejszej pracy opracowano procedurę nieniszczącą, ilościowej oceny grubości warstw chromowych. Do tego celu wykorzystano metodę prądów wirowych, w zakresie analizy fazoczułej, czyli oceny zmian kąta fazowego impedancji w funkcji grubości warstwy. Taka analiza stosowana jest w przypadku pomiarów grubości warstw konduktywnych w zakresie grubości od kilku do kilkuset mikrometrów, wytworzonych na podłożu konduktywnym. Celem właściwej kalibracji parametrów pomiaru, zaprojektowano i wykonano po dwa zestawy próbek referencyjnych z warstwami chromowymi o grubości 15, 30 i 45 μm na podłożu ze stali stopowej 15HM oraz na staliwie węglowym L-200. Z obydwu zestawów próbek pobrano wycinki do badań metalograficznych, które pozwoliły na bezpośredni pomiar grubości warstwy na przygotowanych zgładach. Wyniki tych pomiarów potraktowano jako wartości referencyjne do dalszych badań. Warstwy chromowe uzyskano w procesie nakładania chromu technicznego metodą galwaniczną, przy parametrach zapewniających uzyskanie założonych grubości. Otrzymane wyniki pozwoliły potwierdzić możliwość ilościowej oceny warstw chromowych z dokładnością do 5 μm, z zastosowaniem komercyjnego urządzenia defektoskopowego przeznaczonego do badań metodą prądów wirowych

Keywords:
warstwy chromowe, pomiar grubości, prądy wirowe

2.Jurczak G., Dłużewski P., Finite element modelling of threading dislocation effect on polar GaN/AlN quantum dot, PHYSICA E-LOW-DIMENSIONAL SYSTEMS & NANOSTRUCTURES, ISSN: 1386-9477, DOI: 10.1016/j.physe.2017.08.018, Vol.95, pp.11-15, 2018
Jurczak G., Dłużewski P., Finite element modelling of threading dislocation effect on polar GaN/AlN quantum dot, PHYSICA E-LOW-DIMENSIONAL SYSTEMS & NANOSTRUCTURES, ISSN: 1386-9477, DOI: 10.1016/j.physe.2017.08.018, Vol.95, pp.11-15, 2018

Abstract:
In this paper the effect of adjacent threading dislocation at the edge of the GaN/AlN quantum dot is analysed by use of the finite element analysis. Elastic as well electric effects related to dislocation core are taken into account. Two types of threading dislocations: edge- and screw-type, common for III-nitride epitaxial layers, are considered. Also, three different QD geometries are considered to estimate the impact of the threading dislocation on the quantum heterostructure. It is demonstrated that the local elastic and electric fields around dislocation affect local piezoelectric fields built-in the quantum dot. Local lattice deformation near the dislocation core reduce residual strains in the quantum dot. It is prominent in the case of edge-type dislocation. The presence of an electric charge along dislocation line provides significant shift of the total potential towards the negative values. However, estimated difference in band-to-band transition energy for edge- and screw-type dislocations are rather small, what suggest low sensitivity to the charge density along dislocation line. Unexpectedly, local strain field around the edge-type dislocation, slightly compensate the negative affect of the electrostatic potential.

Keywords:
Quantum dot, Threading dislocation, Piezoelectricity, Finite element modelling

3.Ekiel-Jeżewska M.L., Wajnryb E., Motion of a particle with stick-slip boundary conditions towards a flat interface: hard wall or free surface, Physicochemical Problems of Mineral Processing, ISSN: 1643-1049, DOI: 10.5277/ppmp1849, Vol.54, No.1, pp.203-209, 2018
Ekiel-Jeżewska M.L., Wajnryb E., Motion of a particle with stick-slip boundary conditions towards a flat interface: hard wall or free surface, Physicochemical Problems of Mineral Processing, ISSN: 1643-1049, DOI: 10.5277/ppmp1849, Vol.54, No.1, pp.203-209, 2018

Abstract:
Motion of a particle with stick-slip boundary conditions towards a hard wall or free surface is investigated in the range of Reynolds numbers much smaller than unity, based on the multipole expansion of the Stokes equations. The slip parameter can be interpreted as a measure of a solid particle roughness or as the effect of a surfactant on the motion of a small spherical non-deformable bubble. The particle friction coefficient is evaluated as a function of the distance from its center to the wall, based on the inverse power series expansion, and the results are used to derive explicit lubrication expressions for the friction coefficient, in a wide range of the slip parameters. It is pointed out that for a very small thickness of the fluid film, the lubrication expressions are more accurate than the series expansion. The drainage time is calculated and analyzed, and estimated in terms of explicit lubrication expressions.

Keywords:
particle, boundary conditions, hard wall, free surface

4.Popławski B., Mikułowski G., Mróz A., Jankowski Ł., Decentralized semi-active damping of free structural vibrations by means of structural nodes with an on/off ability to transmit moments, MECHANICAL SYSTEMS AND SIGNAL PROCESSING, ISSN: 0888-3270, DOI: 10.1016/j.ymssp.2017.08.012, Vol.100, pp.926-939, 2018
Popławski B., Mikułowski G., Mróz A., Jankowski Ł., Decentralized semi-active damping of free structural vibrations by means of structural nodes with an on/off ability to transmit moments, MECHANICAL SYSTEMS AND SIGNAL PROCESSING, ISSN: 0888-3270, DOI: 10.1016/j.ymssp.2017.08.012, Vol.100, pp.926-939, 2018

Abstract:
This paper proposes, tests numerically and verifies experimentally a decentralized control algorithm with local feedback for semi-active mitigation of free vibrations in frame structures. The algorithm aims at transferring the vibration energy of low-order, lightly-damped structural modes into high-frequency modes of vibration, where it is quickly damped by natural mechanisms of material damping. Such an approach to mitigation of vibrations, known as the prestress-accumulation release (PAR) strategy, has been earlier applied only in global control schemes to the fundamental vibration mode of a cantilever beam. In contrast, the decentralization and local feedback allows the approach proposed here to be applied to more complex frame structures and vibration patterns, where the global control ceases to be intuitively obvious. The actuators (truss–frame nodes with controllable ability to transmit moments) are essentially unblockable hinges that become unblocked only for very short time periods in order to trigger local modal transfer of energy. The paper proposes a computationally simple model of the controllable nodes, specifies the control performance measure, yields basic characteristics of the optimum control, proposes the control algorithm and then tests it in numerical and experimental examples.

Keywords:
Damping of vibrations, Smart structures, Semi-active control, Decentralized control, Truss-frame nodes

5.Kursa M., Kowalczyk-Gajewska K., Lewandowski M.J., Petryk H., Elastic-plastic properties of metal matrix composites: Validation of mean-field approaches, EUROPEAN JOURNAL OF MECHANICS A-SOLIDS, ISSN: 0997-7538, DOI: 10.1016/j.euromechsol.2017.11.001, Vol.68, pp.53-66, 2018
Kursa M., Kowalczyk-Gajewska K., Lewandowski M.J., Petryk H., Elastic-plastic properties of metal matrix composites: Validation of mean-field approaches, EUROPEAN JOURNAL OF MECHANICS A-SOLIDS, ISSN: 0997-7538, DOI: 10.1016/j.euromechsol.2017.11.001, Vol.68, pp.53-66, 2018

Abstract:
Several micromechanical and numerical approaches to estimating the effective properties of heterogeneous media are analyzed. First, micromechanical mean-field estimates of elastic moduli for selected metal matrix composite systems are compared with the results of finite element calculations performed for two simplified unit cells: spherical and cylindrical. Advantages and deficiencies of such numerical verification of analytical homogenization schemes are indicated. Next, predictions of both approaches are compared with available experimental data for two composite systems for tension and compression tests in the elastic-plastic regime using tangent and secant linearization procedures. In the examined range of strain and ceramic volume content, both the Mori-Tanaka averaging scheme and the generalized self-consistent scheme lead to reliable predictions when combined with the tangent linearization, while the use of secant moduli results in a too stiff response. It is also found that the mean-field predictions for a small ceramic volume content are very close to the results obtained from the finite-element analysis of a spherical unit cell.

Keywords:
Metal-matrix composites, Effective properties, Analytical estimates, Numerical homogenization, Nonlinear analysis

6.Nowak M., Maj M., Determination of coupled mechanical and thermal fields using 2D digital image correlation and infrared thermography: Numerical procedures and results, ARCHIVES OF CIVIL AND MECHANICAL ENGINEERING, ISSN: 1644-9665, DOI: 10.1016/j.acme.2017.10.005, Vol.18, pp.630-644, 2018
Nowak M., Maj M., Determination of coupled mechanical and thermal fields using 2D digital image correlation and infrared thermography: Numerical procedures and results, ARCHIVES OF CIVIL AND MECHANICAL ENGINEERING, ISSN: 1644-9665, DOI: 10.1016/j.acme.2017.10.005, Vol.18, pp.630-644, 2018

Abstract:
The objective of the work is to develop numerical method for determining coupled thermo-mechanical fields based on experimental data obtained from two cameras working in the visible and infrared mode. The sequence of images recorded by the first camera is used to determine the displacement field on the sample surface using the 2D digital image correlation (DIC) method. The resulting field from DIC analysis in a form of a set of discrete points with the corresponding in-plane displacement vector is used as the input for the next step of analysis, where the coupled temperature field is computed. This paper provides a detailed description of the numerical procedures, that allow, to obtain coupled thermal and mechanical fields together with the specification of experimental data needed for calculations. The presented approach was tested on an experimental data obtained during uniaxial tension of the multicrystalline aluminum. The developed numerical routine has been implemented in dedicated software, which can be used for the testing of materials on both a macro and micro scales

Keywords:
Digital image correlation (DIC), Infrared thermography (IRT), Coupled thermo-mechanical fields, Aluminum multicrysta

7.Kochańczyk M., Hlavacek W.S., Lipniacki T., SPATKIN: a simulator for rule-based modeling of biomolecular site dynamics on surfaces , BIOINFORMATICS, ISSN: 1367-4803, DOI: 10.1093/bioinformatics/btx456, Vol.33, No.22, pp.3667-3669, 2017
Kochańczyk M., Hlavacek W.S., Lipniacki T., SPATKIN: a simulator for rule-based modeling of biomolecular site dynamics on surfaces , BIOINFORMATICS, ISSN: 1367-4803, DOI: 10.1093/bioinformatics/btx456, Vol.33, No.22, pp.3667-3669, 2017

Abstract:
Rule-based modeling is a powerful approach for studying biomolecular site dynamics. Here, we present SPATKIN, a general-purpose simulator for rule-based modeling in two spatial dimensions. The simulation algorithm is a lattice-based method that tracks Brownian motion of individual molecules and the stochastic firing of rule-defined reaction events. Because rules are used as event generators, the algorithm is network-free, meaning that it does not require to generate the complete reaction network implied by rules prior to simulation. In a simulation, each molecule (or complex of molecules) is taken to occupy a single lattice site that cannot be shared with another molecule (or complex). SPATKIN is capable of simulating a wide array of membrane-associated processes, including adsorption, desorption and crowding. Models are specified using an extension of the BioNetGen language, which allows to account for spatial features of the simulated process. AVAILABILITY AND IMPLEMENTATION: The C ++ source code for SPATKIN is distributed freely under the terms of the GNU GPLv3 license. The source code can be compiled for execution on popular platforms (Windows, Mac and Linux). An installer for 64-bit Windows and a macOS app are available. The source code and precompiled binaries are available at the SPATKIN Web site (http://pmbm.ippt.pan.pl/software/spatkin).

8.Jeznach O., Gajc M., Korzeb K., Kłos A., Orliński K., Stępień R., Krok-Borkowicz M., Rumian Ł., Pietryga K., Reczyńska K., Pamuła E., Pawlak D.A., New calcium-free Na2O-Al2O3-P2O5 bioactive glasses with potential applications in bone tissue engineering, Journal of the American Ceramic Society, ISSN: 0002-7820, DOI: 10.1111/jace.15216, pp.1-10, 2017
Jeznach O., Gajc M., Korzeb K., Kłos A., Orliński K., Stępień R., Krok-Borkowicz M., Rumian Ł., Pietryga K., Reczyńska K., Pamuła E., Pawlak D.A., New calcium-free Na2O-Al2O3-P2O5 bioactive glasses with potential applications in bone tissue engineering, Journal of the American Ceramic Society, ISSN: 0002-7820, DOI: 10.1111/jace.15216, pp.1-10, 2017

Abstract:
Sodium aluminophosphate glasses were evaluated for their bone repair ability. The glasses belonging to the system 45Na2O–xAl2O3-(55-x)P2O5, with x = (3, 5, 7, 10 mol%) were prepared by a melt-quenching method. We assessed the effect of Al2O3 content on the properties of Na2O–Al2O3–P2O5 (NAP) glasses, which were characterized by density measurements, DSC analyses, solubility, bioactivity in simulated body fluid and cytocompatibility with MG-63 cells. To the best of our knowledge, this is the first investigation of calcium-free Na2O–Al2O3–P2O5 system glasses as bioactive materials for bone tissue engineering.

Keywords:
alumina, bioactive glass, bone tissue engineering, calcium-free bioactive glass, phosphate glass, sodium aluminophosphate glass

9.Fras T., Murzyn A., Pawłowski P., Defeat mechanisms provided by slotted add-on bainitic plates against small-calibre 7.62 mm x 51 AP projectiles., INTERNATIONAL JOURNAL OF IMPACT ENGINEERING, ISSN: 0734-743X, DOI: 10.1016/j.ijimpeng.2017.01.015, Vol.103, pp.241-253, 2017
Fras T., Murzyn A., Pawłowski P., Defeat mechanisms provided by slotted add-on bainitic plates against small-calibre 7.62 mm x 51 AP projectiles., INTERNATIONAL JOURNAL OF IMPACT ENGINEERING, ISSN: 0734-743X, DOI: 10.1016/j.ijimpeng.2017.01.015, Vol.103, pp.241-253, 2017

Abstract:
Thin steel plates with an array of holes, i.e. perforated plates, are used as a passive add-on improving protective properties of armours against small-calibre projectiles. A number of holes in such plates increases the probability of asymmetrical contact between the plate and the projectile, due to which small-calibre projectiles may be destabilized or fragmented before they reach the main-armour. The aim of the study is to analyse the defeat mechanisms provided by 4-mm-thick slotted super-bainitic plates (Pavise™ SBS 600P) against hard-core 7.62mm P80 0.30 AP×51 (0.308 Win) projectiles. To show the dependence between the hit-point and projectile failure, moments when projectiles hit the pre-armour plate were recorded by an ultra-high speed camera and their behaviour after the impact was captured by the flash X-ray radiography. The obtained results complemented by the Lagrangian FEM analysis confirm that slotted steel plates have high protection effectiveness against small-calibre projectiles.

Keywords:
Light-weight ballistic protectionPerforated add-on armourSuper-bainitic steelArmour-piercing (AP) projectile

10.Urbanek O., Sajkiewicz P., Pierini F., The effect of polarity in the electrospinning process on PCL/chitosan nanofibres' structure, properties and efficiency of surface modification, POLYMER, ISSN: 0032-3861, DOI: 10.1016/j.polymer.2017.07.064, Vol.124, pp.168-175, 2017
Urbanek O., Sajkiewicz P., Pierini F., The effect of polarity in the electrospinning process on PCL/chitosan nanofibres' structure, properties and efficiency of surface modification, POLYMER, ISSN: 0032-3861, DOI: 10.1016/j.polymer.2017.07.064, Vol.124, pp.168-175, 2017

Abstract:
The aim of this research was to study the effect of charge polarity applied to the spinning nozzle on the structure and properties of polycaprolactone/chitosan (PCL/CHT) blends, in particular the efficiency of further surface modification by chondroitin sulphate (CS). The observed differences in the morphology and properties of fibres formed at different polarities were interpreted in terms of molecular interactions occurring in the system. FTIR results indicate stronger PCL-chitosan interactions at negative polarity, resulting in lower PCL crystallinity and crystal size distribution determined by DSC, as well as lower wettability. The charge polarity influences PCL/CHT fibre morphology and tailors some of their properties, e.g. wettability, mechanical properties and the efficiency of surface modification. Better efficiency of CS attachment was observed at negative polarity using atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS) is most probably related to higher chitosan content at the fibres' surface being attracted by the negative external potential.

Keywords:
Polycaprolactone/chitosan nanofibres, Charge potential effect in electrospinning, Polycaprolactone-chitosan interactions

11.Ryś M., Skoczeń B., Coupled constitutive model of damage affected two-phase continuum, MECHANICS OF MATERIALS, ISSN: 0167-6636, DOI: 10.1016/j.mechmat.2017.08.015, Vol.115, pp.1-15, 2017
Ryś M., Skoczeń B., Coupled constitutive model of damage affected two-phase continuum, MECHANICS OF MATERIALS, ISSN: 0167-6636, DOI: 10.1016/j.mechmat.2017.08.015, Vol.115, pp.1-15, 2017

Abstract:
A broad class of metastable materials, including selected alloys (e.g. stainless steels) used for applications in radiation environment (particle accelerators), is characterized by simultaneous occurrence of the plastic strain driven phase transformation and evolution of nano/micro damage. Plastic flow in such materials is usually accompanied by dynamic evolution of microstructure, resulting from the strain induced fcc-bcc phase transformation. Two-phase continuum is composed of austenitic matrix (fcc) and martensitic inclusions (bcc), represented by type Eshelby ellipsoidal entities embedded in ductile matrix. The matrix remains entirely plastic, and contains micro-cracks and micro-voids representing ductile damage. On the other hand, the inclusions are characterized by much higher yield stress and their behavior is generally brittle. Thus, brittle damage develops in the inclusions. The origin of damage is mechanical (manufacturing and load induced defects), and related to the source of radiation (primary or secondary particles flux). Among the lattice defects induced by radiation, the clusters of nano/micro voids are accounted for. The constitutive model takes into account the evolution of mechanically and radiation induced nano/micro damage in the presence of microstructure evolution, reflected by the plastic strain driven dynamic change of proportions between the matrix and the inclusions. The model is multiscale since the processes that occur at different scales (micro, meso, macro) are addressed, and coupled, since both phenomena: phase transformation and damage are described by coupled equations. Application to irradiated corrugated shells, components of thermo-mechanical compensation systems, are presented.

12.Ranachowski Z., Schabowicz K., The contribution of fiber reinforcement system to the overall toughness of cellulose fiber concrete panels, CONSTRUCTION AND BUILDING MATERIALS, ISSN: 0950-0618, DOI: 10.1016/j.conbuildmat.2017.09.067, Vol.156, pp.1028-1034, 2017
Ranachowski Z., Schabowicz K., The contribution of fiber reinforcement system to the overall toughness of cellulose fiber concrete panels, CONSTRUCTION AND BUILDING MATERIALS, ISSN: 0950-0618, DOI: 10.1016/j.conbuildmat.2017.09.067, Vol.156, pp.1028-1034, 2017

Abstract:
The paper concerns the role of cellulose reinforcements in overall mechanical toughness of fiber concrete panels applied as facade building material. The results of mechanical tests performed on specimens in as delivered state as well as on specimens which underwent the procedure of destruction of internal fiber network structure due to pyrolysis are presented. The results of mechanical tests let the authors to calculate the work of fracture for six different mechanical conditions. Moreover the analysis of registered Acoustic Emission (AE) signal had revealed that the investigated process of destruction begins with the brittle crack generation and growth while major damages of reinforcement system appears in later phase of the process.

Keywords:
Fiber cement panels, Cellulose fibers, Brittle crack, Acoustic Emission

13.Piechocka I.K., Kurniawan N.A., Grimbergen J., Koopman J., Koenderink G.H., Recombinant fibrinogen reveals the differential roles of α- and γ-chain cross-linking and molecular heterogeneity in fibrin clot strain-stiffening, Journal of Thrombosis and Haemostasis, ISSN: 1538-7933, DOI: 10.1111/jth.13650, Vol.15, No.5, pp.938-949, 2017
Piechocka I.K., Kurniawan N.A., Grimbergen J., Koopman J., Koenderink G.H., Recombinant fibrinogen reveals the differential roles of α- and γ-chain cross-linking and molecular heterogeneity in fibrin clot strain-stiffening, Journal of Thrombosis and Haemostasis, ISSN: 1538-7933, DOI: 10.1111/jth.13650, Vol.15, No.5, pp.938-949, 2017

Abstract:
Essentials Fibrinogen circulates in human plasma as a complex mixture of heterogeneous molecular variants. We measured strain-stiffening of recombinantly produced fibrinogen upon clotting. Factor XIII and molecular heterogeneity alter clot elasticity at the protofibril and fiber level. This highlights the hitherto unknown role of molecular composition in fibrin clot mechanics.

Keywords:
blood coagulation, elasticity, fibrin, polymers, rheology, turbidimetry

14.Krajewski M., Magnetic-field-induced synthesis of magnetic wire-like micro- and nanostructures, NANOSCALE, ISSN: 2040-3364, DOI: 10.1039/c7nr05823c, Vol.9, No.43, pp.16511-16545, 2017
Krajewski M., Magnetic-field-induced synthesis of magnetic wire-like micro- and nanostructures, NANOSCALE, ISSN: 2040-3364, DOI: 10.1039/c7nr05823c, Vol.9, No.43, pp.16511-16545, 2017

Abstract:
A lot of physical and chemical preparation methods of one-dimensional (1D) structures are known today. Most of them use highly advanced technology or quite complex chemical reagents. This results in their high costs and difficulties with their implementation to a large industrial scale. Hence, new, facile and inexpensive approaches are still sought. One alternative to wire-like structure production is based on the chemical reduction reactions combined with an external magnetic field, which acts as an independent synthesis parameter. This approach is commonly called magnetic-field-assisted (MFA) synthesis or magnetic-field-induced (MFI) synthesis. As usual, this manufacturing strategy comprises both drawbacks and advantages, which are introduced in this review. Moreover, this work shows that MFI synthesis depends on several synthesis parameters including the strength of the applied magnetic field, reaction temperature, pH value of the reaction environment, chemical composition of the precursor solution, reaction time, and also the presence of surfactants, complexing agents, nucleating agents, initiators as well as organic solvents. All of them have an impact on the morphology and dimensions of wire-like materials and their chemical, physical and mechanical properties. Finally, the opportunities and challenges associated with the magnetic-assisted fabrication of wire-like structures are widely discussed in this review

Keywords:
magnetic-field-induced synthesis, nanowire, microwire, nanochain, nanostructure, one-dimensional nanostructures

15.Banach Z., Larecki W., Kershaw-type transport equations for fermionic radiation, ZEITSCHRIFT FUR ANGEWANDTE MATHEMATIK UND PHYSIK ZAMP, ISSN: 0044-2275, DOI: 10.1007/s00033-017-0847-z, Vol.68, No.4, pp.100-1-100-24, 2017
Banach Z., Larecki W., Kershaw-type transport equations for fermionic radiation, ZEITSCHRIFT FUR ANGEWANDTE MATHEMATIK UND PHYSIK ZAMP, ISSN: 0044-2275, DOI: 10.1007/s00033-017-0847-z, Vol.68, No.4, pp.100-1-100-24, 2017

Abstract:
Besides the maximum entropy closure procedure, other procedures can be used to close the systems of spectral moment equations. In the case of classical and bosonic radiation, the closed-form analytic Kershaw-type and B-distribution closure procedures have been used. It is shown that the Kershaw-type closure procedure can also be applied to the spectra moment equations of fermionic radiation. First, a description of the Kershaw-type closure for the system consisting of an arbitrary number of one-dimensional moment equations is presented. Next, the Kershaw-type two-field and three-field transport equations for fermionic radiation are analyzed. In the first case, the independent variables are the energy density and the heat flux. The second case includes additionally the flux of the heat flux as an independent variable. The generalization of the former two-field case to three space dimensions is also presented. The fermionic Kershaw-type closures differ from those previously derived for classical and bosonic radiation. It is proved that the obtained one-dimensional systems of transport equations are strictly hyperbolic and causal. The fermionic Kershaw-type closure functions behave qualitatively in the same way as the fermionic maximum entropy closure functions, but attain different numerical values.

Keywords:
Fermionic radiation, Moment equations, Moment realizability problem, Kershaw-type closure, Three-moment transport

16.Jarecki L., Misztal-Faraj B., Non-linear stress-orientation behavior of flexible chain polymers under fast elongational flow, EUROPEAN POLYMER JOURNAL, ISSN: 0014-3057, DOI: 10.1016/j.eurpolymj.2017.08.028, Vol.95, pp.368-381, 2017
Jarecki L., Misztal-Faraj B., Non-linear stress-orientation behavior of flexible chain polymers under fast elongational flow, EUROPEAN POLYMER JOURNAL, ISSN: 0014-3057, DOI: 10.1016/j.eurpolymj.2017.08.028, Vol.95, pp.368-381, 2017

Abstract:
Closed-form analytical formulas are proposed for non-linear stress-orientation relation valid in the entire range of tensile stresses, intermediate and high, basing on the inverse Langevin chain statistics. Tensile force and orientation characteristics for single, flexible chain macromolecule are reconsidered in a closed-form Padè approximation of the inverse Langevin function in the entire range of chain extensions, as well as the dynamics of molecular deformation and orientation for systems of chains subjected to uniaxial elongational flow. Average stress and orientation tensors, not collinear in the non-linear range, as well as the tensile stress and axial orientation factor of the chain segments in the system are calculated. For the intermediate tensile stresses, the closed-form formula is derived in the first non-Gaussian term approximation of the inverse Langevin function with the assumption of dominating longitudinal elongation of the chains. The high-stress non-linearity formula is derived with the Padè and Peterlin modulus approximations and aligned chain end-to-end vectors by the flow. Both formulas are validated by exact numerical calculations without the assumptions and influence of the approximations is estimated. Ranges of applicability of the formulas are illustrated and examples of their application are presented.

Keywords:
Molecular orientation, Tensile stress, Non-linear stress-orientation behavior, Elongational flow, Langevin chain statistics

17.Colabella L., Cisilino A.P., Häiat G., Kowalczyk P., Mimetization of the elastic properties of cancellous bone via a parameterized cellular material, Biomechanics and Modeling in Mechanobiology, ISSN: 1617-7959, DOI: 10.1007/s10237-017-0901-y, Vol.16, No.5, pp.1485-1502, 2017
Colabella L., Cisilino A.P., Häiat G., Kowalczyk P., Mimetization of the elastic properties of cancellous bone via a parameterized cellular material, Biomechanics and Modeling in Mechanobiology, ISSN: 1617-7959, DOI: 10.1007/s10237-017-0901-y, Vol.16, No.5, pp.1485-1502, 2017

Abstract:
Bone tissue mechanical properties and trabecular microarchitecture are the main factors that determine the biomechanical properties of cancellous bone. Artificial cancellous microstructures, typically described by a reduced number of geometrical parameters, can be designed to obtain a mechanical behavior mimicking that of natural bone. In this work, we assess the ability of the parameterized microstructure introduced by Kowalczyk (Comput Methods Biomech Biomed Eng 9:135–147, 2006. doi:10.1080/10255840600751473) to mimic the elastic response of cancellous bone. Artificial microstructures are compared with actual bone samples in terms of elasticity matrices and their symmetry classes. The capability of the parameterized microstructure to combine the dominant isotropic, hexagonal, tetragonal and orthorhombic symmetry classes in the proportions present in the cancellous bone is shown. Based on this finding, two optimization approaches are devised to find the geometrical parameters of the artificial microstructure that better mimics the elastic response of a target natural bone specimen: a Sequential Quadratic Programming algorithm that minimizes the norm of the difference between the elasticity matrices, and a Pattern Search algorithm that minimizes the difference between the symmetry class decompositions. The pattern search approach is found to produce the best results. The performance of the method is demonstrated via analyses for 146 bone samples.

Keywords:
Cancellous bone, Parameterized microstructure, Elastic properties, Homogenization, Symmetry classes, Optimization

18.Piotrzkowska-Wróblewska H., Dobruch-Sobczak K., Byra M., Nowicki A., Open access database of raw ultrasonic signals acquired from malignant and benign breast lesions, Medical Physics, ISSN: 0094-2405, DOI: 10.1002/mp.12538, Vol.44, No.9, pp.1-5, 2017
Piotrzkowska-Wróblewska H., Dobruch-Sobczak K., Byra M., Nowicki A., Open access database of raw ultrasonic signals acquired from malignant and benign breast lesions, Medical Physics, ISSN: 0094-2405, DOI: 10.1002/mp.12538, Vol.44, No.9, pp.1-5, 2017

Abstract:
Purpose: The aim of this paper is to provide access to a database consisting of the raw radio-frequency ultrasonic echoes acquired from malignant and benign breast lesions. The database is freely available for study and signal analysis.
Acquisition and validation methods: The ultrasonic radio-frequency echoes were recorded from breast focal lesions of patients of the Institute of Oncology in Warsaw. The data were collected between 11/2013 and 10/2015. Patients were examined by a radiologist with 18 yr’ experience in the ultrasonic examination of breast lesions. The set of data includes scans from 52 malignant and 48 benign breast lesions recorded in a group of 78 women. For each lesion, two individual orthogonal scans from the pathological region were acquired with the Ultrasonix SonixTouch Research ultrasound scanner using the L14-5/38 linear array transducer. All malignant lesions were histologically assessed by core needle biopsy. In the case of benign lesions, part of them was histologically assessed and another part was observed over a 2-year period. Data format and usage notes: The radio-frequency echoes were stored in Matlab file format. For each scan, the region of interest was provided to correctly indicate the lesion area. Moreover, for each lesion, the BI-RADS category and the lesion class were included. Two code examples of data manipulation are presented. The data can be downloaded via the Zenodo repository (https://doi.org/10.5281/zenodo.545928) or the website http ://bluebox.ippt.gov.pl/~hpiotrzk.
Potential applications: The database can be used to test quantitative ultrasound techniques and ultrasound image processing algorithms, or to develop computer-aided diagno sis systems.

Keywords:
breast lesions, dataset, ultrasonic signals, ultrasonography

19.Lanzi M., Salatelli E., Giorgini L., Mucci A., Pierini F., Di-Nicola F.P., Water-soluble polythiophenes as efficient charge-transport layers for the improvement of photovoltaic performance in bulk heterojunction polymeric solar cells, EUROPEAN POLYMER JOURNAL, ISSN: 0014-3057, DOI: 10.1016/j.eurpolymj.2017.10.032, Vol.97, pp.378-388, 2017
Lanzi M., Salatelli E., Giorgini L., Mucci A., Pierini F., Di-Nicola F.P., Water-soluble polythiophenes as efficient charge-transport layers for the improvement of photovoltaic performance in bulk heterojunction polymeric solar cells, EUROPEAN POLYMER JOURNAL, ISSN: 0014-3057, DOI: 10.1016/j.eurpolymj.2017.10.032, Vol.97, pp.378-388, 2017

Abstract:
Water-soluble regioregular poly{3-[(6-sodium sulfonate)hexyl]thiophene} (PT6S) and poly{3-[(6-trimethylammoniumbromide)hexyl]thiophene} (PT6N) have been synthesized and employed both as photoactive layers for the assembling of “green” bulk-heterojunction organic solar cells and as charge-collection layers in a cell with “classic” architecture. While the photovoltaic performances obtained with the two aforementioned polymers were lower than the reference cell, their latter use allowed to notably increase the inherent J-V properties, leading to a considerable enhancement in the overall photovoltaic output. The power conversion efficiency of the optimized multilayer BHJ solar cell reached 4.78%, revealing a higher efficiency than the reference cell (3.63%).

Keywords:
Water-soluble polymer, Polythiophene derivative, Bulk heterojunction, Organic photovoltaic, Interfacial layer

20.Zakrzewska K.E., Samluk A., Wencel A., Dudek K., Pijanowska D.G., Pluta K.D., Liver tissue fragments obtained from males are the most promising source of human hepatocytes for cell-based therapies – Flow cytometric analysis of albumin expression, PLOS ONE, ISSN: 1932-6203, DOI: 10.1371/journal.pone.0182846, Vol.12, No.8, pp.1-14, 2017
Zakrzewska K.E., Samluk A., Wencel A., Dudek K., Pijanowska D.G., Pluta K.D., Liver tissue fragments obtained from males are the most promising source of human hepatocytes for cell-based therapies – Flow cytometric analysis of albumin expression, PLOS ONE, ISSN: 1932-6203, DOI: 10.1371/journal.pone.0182846, Vol.12, No.8, pp.1-14, 2017

Abstract:
Cell-based therapies that could provide an alternative treatment for the end-stage liver disease require an adequate source of functional hepatocytes. There is little scientific evidence for the influence of patient’s age, sex, and chemotherapy on the cell isolation efficiency and metabolic activity of the harvested hepatocytes. The purpose of this study was to investigate whether hepatocytes derived from different sources display differential viability and biosynthetic capacity. Liver cells were isolated from 41 different human tissue specimens. Hepatocytes were labeled using specific antibodies and analyzed using flow cytometry. Multiparametric analysis of the acquired data revealed statistically significant differences between some studied groups of patients. Generally, populations of cells isolated from the male specimens had greater percentage of biosynthetically active hepatocytes than those from the female ones regardless of age and previous chemotherapy of the patient. Based on the albumin staining (and partially on the α-1-antitrypsin labeling) after donor liver exclusion (6 out of 41 samples), our results indicated that: 1. samples obtained from males gave a greater percentage of active hepatocytes than those from females (p = 0.034), and 2. specimens from the males after chemotherapy greater than those from the treated females (p = 0.032).

21.Pawłowska S., Nakielski P., Pierini F., Piechocka I.K., Zembrzycki K., Kowalewski T.A., Lateral migration of electrospun hydrogel nanofilaments in an oscillatory flow, PLOS ONE, ISSN: 1932-6203, DOI: 10.1371/journal.pone.0187815, Vol.12, No.11, pp.1-21, 2017
Pawłowska S., Nakielski P., Pierini F., Piechocka I.K., Zembrzycki K., Kowalewski T.A., Lateral migration of electrospun hydrogel nanofilaments in an oscillatory flow, PLOS ONE, ISSN: 1932-6203, DOI: 10.1371/journal.pone.0187815, Vol.12, No.11, pp.1-21, 2017

Abstract:
The recent progress in bioengineering has created great interest in the dynamics and manipulation of long, deformable macromolecules interacting with fluid flow. We report experimental data on the cross-flow migration, bending, and buckling of extremely deformable hydrogel nanofilaments conveyed by an oscillatory flow into a microchannel. The changes in migration velocity and filament orientation are related to the flow velocity and the filament’s initial position, deformation, and length. The observed migration dynamics of hydrogel filaments qualitatively confirms the validity of the previously developed worm-like bead-chain hydrodynamic model. The experimental data collected may help to verify the role of hydrodynamic interactions in molecular simulations of long molecular chains dynamics.

22.Maździarz M., Mrozek A., Kuś W., Burczyński T., First-principles study of new X-graphene and Y-graphene polymorphs generated by the two stage strategy, MATERIALS CHEMISTRY AND PHYSICS, ISSN: 0254-0584, DOI: 10.1016/j.matchemphys.2017.08.066, Vol.202, pp.7-14, 2017
Maździarz M., Mrozek A., Kuś W., Burczyński T., First-principles study of new X-graphene and Y-graphene polymorphs generated by the two stage strategy, MATERIALS CHEMISTRY AND PHYSICS, ISSN: 0254-0584, DOI: 10.1016/j.matchemphys.2017.08.066, Vol.202, pp.7-14, 2017

Abstract:
Two potentially new, 2D-graphene-like materials have been generated by the two stage searching strategy combining molecular and ab initio approach. The two candidates obtained from the evolutionary based algorithm and molecular calculations were then in depth analysed using first-principles Density Functional Theory from the mechanical, structural, phonon and electronic properties point of view. Both proposed polymorphs of graphene (oP8-P2mm) are mechanically and dynamically stable and can be metallic-like.

Keywords:
Carbon; Graphene; Ab initio calculations; Mechanical properties; Elastic properties

23.Pierini F., Lanzi M., Nakielski P., Kowalewski T.A., Electrospun Polyaniline-Based Composite Nanofibers: Tuning the Electrical Conductivity by Tailoring the Structure of Thiol-Protected Metal Nanoparticles, Journal of Nanomaterials, ISSN: 1687-4110, DOI: 10.1155/2017/6142140, Vol.2017, pp.1-10, 2017
Pierini F., Lanzi M., Nakielski P., Kowalewski T.A., Electrospun Polyaniline-Based Composite Nanofibers: Tuning the Electrical Conductivity by Tailoring the Structure of Thiol-Protected Metal Nanoparticles, Journal of Nanomaterials, ISSN: 1687-4110, DOI: 10.1155/2017/6142140, Vol.2017, pp.1-10, 2017

Abstract:
Composite nanofibers made of a polyaniline-based polymer blend and different thiol-capped metal nanoparticles were prepared using ex situ synthesis and electrospinning technique. The effects of the nanoparticle composition and chemical structure on the electrical properties of the nanocomposites were investigated. This study confirmed that Brust’s procedure is an effective method for the synthesis of sub-10 nm silver, gold, and silver-gold alloy nanoparticles protected with different types of thiols. Electron microscopy results demonstrated that electrospinning is a valuable technique for the production of composite nanofibers with similar morphology and revealed that nanofillers are well-dispersed into the polymer matrix. X-ray diffraction tests proved the lack of a significant influence of the nanoparticle chemical structure on the polyaniline chain arrangement. However, the introduction of conductive nanofillers in the polymer matrix influences the charge transport noticeably improving electrical conductivity. The enhancement of electrical properties is mediated by the nanoparticle capping layer structure. The metal nanoparticle core composition is a key parameter, which exerted a significant influence on the conductivity of the nanocomposites. These results prove that the proposed method can be used to tune the electrical properties of nanocomposites.

24.Egner H., Ryś M., Total energy equivalence in constitutive modeling of multidissipative materials, INTERNATIONAL JOURNAL OF DAMAGE MECHANICS, ISSN: 1056-7895, DOI: 10.1177/1056789516679496, Vol.26, No.3, pp.417-446, 2017
Egner H., Ryś M., Total energy equivalence in constitutive modeling of multidissipative materials, INTERNATIONAL JOURNAL OF DAMAGE MECHANICS, ISSN: 1056-7895, DOI: 10.1177/1056789516679496, Vol.26, No.3, pp.417-446, 2017

Abstract:
In the present work, the total energy equivalence hypothesis was applied in constitutive modeling of engineering materials. The approach originally developed for damaged materials, was extended to modeling not only damage but also other dissipative phenomena, like phase transformation, in a consistent manner. The proposed model was examined by means of parametric studies to show its ability to reflect different experimentally observed features of real materials.

Keywords:
Constitutive modeling, dissipative material, plasticity, damage, phase transformation

25.Takeda K., Matsui R., Tobushi H., Pieczyska E.A., Torsional deformation properties of SMA tapes and their application to bias-type reciprocating rotary driving actuator, ARCHIVES OF MECHANICS, ISSN: 0373-2029, Vol.69, No.4-5, pp.289-303, 2017
Takeda K., Matsui R., Tobushi H., Pieczyska E.A., Torsional deformation properties of SMA tapes and their application to bias-type reciprocating rotary driving actuator, ARCHIVES OF MECHANICS, ISSN: 0373-2029, Vol.69, No.4-5, pp.289-303, 2017

Abstract:
In order to develop the reciprocating rotary driving actuator with a simple mechanism using shape memory alloy (SMA) tapes, the graphical method to design the actuator was proposed based on the torsional deformation properties of SMA tapes. The torsional deformation properties of the SME tape showing the shape memory effect (SME) and the SE tape showing superelasticity (SE) were obtained. The bias-type reciprocating rotary actuator was composed of the pretwisted SME tape and the flat SE tape in series. The design chart expressed by the relationship between torque and twisting angle of the SME tape and the SE tape was proposed. The rotational angle and torque, which vary depending on temperature, can be estimated based on the design chart. The rotational angle is controlled by adjusting the mounting angle of the SME tape and the heating temperature. The automatically opening and closing blind driven by sunlight was demonstrated. The blind was controlled by using the reciprocating rotary element composed of the SME tape and the SE tape. The behavior of the blind can be achieved based on the proposed design method of the reciprocating rotary driving element

Keywords:
shape memory alloy, tape, torsion, actuator, reciprocating rotation, design chart, bias-type

26.Dobruch-Sobczak K., Piotrzkowska-Wróblewska H., Roszkowska-Purska K., Nowicki A., Jakubowski W., Usefulness of combined BI-RADS analysis and Nakagami statistics of ultrasound echoes in the diagnosis of breast lesions, Clinical Radiology, ISSN: 0009-9260, DOI: 10.1016/j.crad.2016.11.009, Vol.72, pp.339.e7-339.e15, 2017
Dobruch-Sobczak K., Piotrzkowska-Wróblewska H., Roszkowska-Purska K., Nowicki A., Jakubowski W., Usefulness of combined BI-RADS analysis and Nakagami statistics of ultrasound echoes in the diagnosis of breast lesions, Clinical Radiology, ISSN: 0009-9260, DOI: 10.1016/j.crad.2016.11.009, Vol.72, pp.339.e7-339.e15, 2017

Abstract:
AIM: To develop a method combining the statistics of the ultrasound backscatter and the Breast Imaging-Reporting and Data System (BI-RADS) classification to enhance the differentiation of breast tumours.
MATERIALS AND METHODS: The Nakagami shape parameter m was used to characterise the scatter properties of breast tumours. Raw data from the radiofrequency (RF) echo-signal and Bmode images from 107 (32 malignant and 75 benign) lesions and their surrounding tissue were recorded. Three different characteristic values of the shape parameters of m (maximum [mLmax], minimum [mLmin] and average [mLavg]) and differences between m parameters (Dmmax, Dmmin, Dmavg) of the lesions and their surrounding tissues were assessed. A lesion with a BI-RADS score of 3 was considered benign, while a lesion with a score of 4 was considered malignant (a cut-off of BI-RADS 3/4 was set for all patients).
RESULTS: The area under the receiver operating characteristic (ROC) curve (AUC) was equal to 0.966 for BI-RADS, with 100% sensitivity and 54.67% specificity. All malignant lesions were diagnosed correctly, whereas 34 benign lesions were biopsied unnecessarily. In assessing the Nakagami statistics, the sum of the sensitivity and specificity was the best for mLavg (62.5% and 93.33%, respectively). Only four of 20 lesions were found over the cut-off value in BI-RADS of 4a. When comparing the differences in m parameters, Dmavg had the highest sensitivity of 90% (only three of 32 lesions were false negative). These three lesions were classified as BIRADS category 4c. The combined use of B-mode and mLmin parameter improve the AUC up to 0.978 (pĽ0.088), compared to BI-RADS alone.
CONCLUSION: The combination of the parametric imaging and the BI-RADS assessment does not significantly improve the differentiation of breast lesions, but it has the potential to better identify the group of patients with mainly benign lesions that have a low level of suspicion for malignancy with a BI-RADS score of 4a.

27.Bajer C.I., Dyniewicz B., Shillor M., A Gao beam subjected to a moving inertial point load, Mathematics and Mechanics of Solids, ISSN: 1081-2865, DOI: 10.1177/1081286517718229, pp.1-12, 2017
Bajer C.I., Dyniewicz B., Shillor M., A Gao beam subjected to a moving inertial point load, Mathematics and Mechanics of Solids, ISSN: 1081-2865, DOI: 10.1177/1081286517718229, pp.1-12, 2017

Abstract:
A model for the dynamics of a Gao elastic or viscoelastic nonlinear beam that is subject to a horizontally moving vertical point-force is modeled and computationally studied. In particular, the behavior and vibrations of the beam as the mass is moving on it is investigated. Such problems arise naturally in transportation systems with rails. A time-marching finite element numerical algorithm for the problem is developed and implemented. Results of representative simulations are depicted and compared to the behavior of a linear Euler beam with a moving mass.

Keywords:
Gao beam, moving inertial point load, Finite Element simulations, beam vibration

28.Rojek J., Nosewicz S., Chmielewski M., MICRO-MACRO RELATIONSHIPS FROM DISCRETE ELEMENT SIMULATIONS OF SINTERING, INTERNATIONAL JOURNAL FOR MULTISCALE COMPUTATIONAL ENGINEERING, ISSN: 1543-1649, DOI: 10.1615/IntJMultCompEng.2017020322, Vol.15, No.4, pp.323-342, 2017
Rojek J., Nosewicz S., Chmielewski M., MICRO-MACRO RELATIONSHIPS FROM DISCRETE ELEMENT SIMULATIONS OF SINTERING, INTERNATIONAL JOURNAL FOR MULTISCALE COMPUTATIONAL ENGINEERING, ISSN: 1543-1649, DOI: 10.1615/IntJMultCompEng.2017020322, Vol.15, No.4, pp.323-342, 2017

Abstract:
A two-scale modeling framework for sintering processes has been presented. Formulation of the micromechanical model of sintering developed in the discrete element method and basic relationships in the macroscopic model of sintering have been briefly reviewed. The methodology to determine macroscopic quantities–stress, strains, and constitutive viscous properties-from the discrete element simulations has been presented. This methodology has been applied to modeling of NiAl sintering. First, the discrete element model (DEM) has been calibrated by fitting the numerical densification curve to the experimental data. The DEM model with calibrated parameters has been used in simulations specially conceived to give macroscopic viscous moduli of the sintered material. Using the averaging procedures macroscopic stresses and strains have been calculated. Strain rates have been obtained differentiating the strain curves with respect to time. Finally, the viscous constitutive properties of the sintered material have been determined. The dependence of the shear and volumetric viscous moduli on the relative density (or equivalently) on the porosity has been obtained. It has been found that the numerical simulations predict a similar dependence as that assumed in the phenomenological macroscopic models. Thus, the validity of the micro-macro relationships obtained from the discrete element simulations of powder sintering has been confirmed. The proposed methodology allows us to use the discrete element model in the framework of multiscale modeling of sintering.

Keywords:
discrete element method, sintering, simulation, micro-macro relationships, multiscale modeling

29.Maździarz M., Rojek J., Nosewicz S., ESTIMATION OF MICROMECHANICAL NiAl SINTERING MODEL PARAMETERS FROM THE MOLECULAR SIMULATIONS, INTERNATIONAL JOURNAL FOR MULTISCALE COMPUTATIONAL ENGINEERING, ISSN: 1543-1649, DOI: 10.1615/IntJMultCompEng.2017020289 , Vol.15, No.4, pp.343-358, 2017
Maździarz M., Rojek J., Nosewicz S., ESTIMATION OF MICROMECHANICAL NiAl SINTERING MODEL PARAMETERS FROM THE MOLECULAR SIMULATIONS, INTERNATIONAL JOURNAL FOR MULTISCALE COMPUTATIONAL ENGINEERING, ISSN: 1543-1649, DOI: 10.1615/IntJMultCompEng.2017020289 , Vol.15, No.4, pp.343-358, 2017

Abstract:
Molecular statics/dynamics estimation of constitutive parameters for a micromechanical NiAl sintering model is reported in this paper. The parameters include temperature-dependent diffusion coefficients, surface energy, and linear thermal expansion. These parameters define material behavior during sintering and are used in the sintering particle model implemented in the discrete element model. The investigated material, the NiAl intermetallic, belongs to novel materials characterized by advantageous mechanical properties. Various machine elements are manufactured from a pure NiAl powder or from powder mixtures containing the NiAl using the sintering technology. It is well known that sintering is governed by diffusion. Therefore diffusive properties are important parameters of the micromechanical model of sintering. Numerical estimation of the model parameters by simulations at the lower scale is a powerful tool alternative to experimental methods. Molecular statics and dynamics models for NiAl have been created using the embedded atom model potential. Numerical simulations have allowed us to estimate the volume, surface, and grain-boundary diffusivity for the B2-type NiAl in the 1573 to 1673 K temperature range. Dependence of the diffusion coefficients on temperature has been determined and validity of the Arrhenius-type temperature dependency has been assessed. The parameters evaluated numerically have been compared with available experimental data as well as with theoretical predictions obtained with other methods. Many of the results presented in this paper have a pioneer character and are not known in the literature.

Keywords:
NiAl, sintering, diffusivity, molecular dynamics, molecular statics, nanoparticles

30.Pęcherski R.B., Nowak M., Nowak Z., VIRTUAL METALLIC FOAMS. APPLICATION FOR DYNAMIC CRUSHING ANALYSIS, INTERNATIONAL JOURNAL FOR MULTISCALE COMPUTATIONAL ENGINEERING, ISSN: 1543-1649, Vol.15, No.5, pp.431-442, 2017
Pęcherski R.B., Nowak M., Nowak Z., VIRTUAL METALLIC FOAMS. APPLICATION FOR DYNAMIC CRUSHING ANALYSIS, INTERNATIONAL JOURNAL FOR MULTISCALE COMPUTATIONAL ENGINEERING, ISSN: 1543-1649, Vol.15, No.5, pp.431-442, 2017

Abstract:
The subject of the study are the models based on digital microstructures, in particular open-cell metallic foams characterized with the skeleton formed of convex or re-entrant cells. Recently, the auxetic materials revealing negative Poisson’s ratio have attracted increasing attention in the context of modern materials applications. Up to date, the research of auxetics is mainly concentrating on the cell structure design and the analysis of quasi-static response. The dynamic properties of such materials are less known. Impact compressions of the two kind of foams under high-velocity are numerically analyzed. To simulate the deformation processes the finite element program ABAQUS is used. The computer tomography makes the basis for the formulation of computational model of virtual foam and the finite element discretization of the skeleton. For numerical simulations the constitutive elasto-viscoplasticity model is applied that defines the dynamic behavior of oxygen-free high conductivity (OFHC) Cu using the experimental data reported in the literature. The numerical predictions of crushing force for velocity 50 and 300 m/s are discussed

Keywords:
compression test, open-cell copper, convex cell, re-entrant cell, virtual cellular materials, metallic foams, numerical simulation

31.Cichocki B., Ekiel-Jeżewska M.L., Wajnryb E., Translational and rotational Brownian displacements of colloidal particles of complex shapes, ARCHIVES OF MECHANICS, ISSN: 0373-2029, Vol.69, No.3, pp.257-267, 2017
Cichocki B., Ekiel-Jeżewska M.L., Wajnryb E., Translational and rotational Brownian displacements of colloidal particles of complex shapes, ARCHIVES OF MECHANICS, ISSN: 0373-2029, Vol.69, No.3, pp.257-267, 2017

Abstract:
The exact analytical expressions for the time-dependent cross-correlations of the translational and rotational Brownian displacements of a particle with arbitrary shape were derived by us in [3, 4]. They are in this work applied to construct a method to analyze the Brownian motion of a particle of an arbitrary shape, and to extract accurately the self-diffusion matrix from the measurements of the crosscorrelations, which in turn allows to gain some information on the particle structure. As an example, we apply our new method to analyze the experimental results of D. J. Kraft et al. for the micrometer-sized aggregates of the beads [8]. We explicitly demonstrate that our procedure, based on the measurements of the time-dependent cross-correlations in the whole range of times, allows to determine the self-diffusion (or alternatively the friction matrix) with a much higher precision than the method based only on their initial slopes. Therefore, the analytical time-dependence of the cross-correlations serves as a useful tool to extract information about particle structure from trajectory measurements.

Keywords:
Brownian motion, Smoluchowski equation, hydrodynamic interactions, self-diffusion matrix, friction coefficients, cross-correlations of translational and rotational Brownian displacements

32.Moćko W., Radziejewska J., Sarzyński A., Strzelec M., Marczak J., Analysis of the plastic deformation of AISI 304 steel induced by the nanosecond laser pulse, OPTICS & LASER TECHNOLOGY, ISSN: 0030-3992, DOI: 10.1016/j.optlastec.2016.11.022, Vol.90, pp.165-173, 2017
Moćko W., Radziejewska J., Sarzyński A., Strzelec M., Marczak J., Analysis of the plastic deformation of AISI 304 steel induced by the nanosecond laser pulse, OPTICS & LASER TECHNOLOGY, ISSN: 0030-3992, DOI: 10.1016/j.optlastec.2016.11.022, Vol.90, pp.165-173, 2017

Abstract:
The paper presents result of experimental and numerical tests of plastic deformation of austenitic steel generated by a nanosecond laser pulse. The shock wave generated by the laser pulse was used to induce local plastic deformation of the material. The study examined the possibility of using the process to develop a laser forming of materials under ultra-high strain rate. It has been shown that the laser pulse with intensity 2.5 GW/cm2 induces a repeatable plastic deformation of commercially available 304 steel without thermal effects on the surface

Keywords:
Laser pulse, Plastic deformations, Microstructure, Numerical simulations

33.Roszkiewicz A., Nasalski W., Transmission and reflection properties of two-dimensional finite metal crystals, EUROPEAN PHYSICAL JOURNAL D, ISSN: 1434-6060, DOI: 10.1140/epjd/e2017-70706-9, Vol.71, No.182, pp.1-12, 2017
Roszkiewicz A., Nasalski W., Transmission and reflection properties of two-dimensional finite metal crystals, EUROPEAN PHYSICAL JOURNAL D, ISSN: 1434-6060, DOI: 10.1140/epjd/e2017-70706-9, Vol.71, No.182, pp.1-12, 2017

Abstract:
Optical characteristics of a finite two-dimensional silver stripe photonic crystal of a square lattice are numerically analysed with use of multilayer Rigorous Coupled Wave Analysis. Qualitative changes in optical response of the crystal originated from modifications of the thickness and filling factors of each layer and the polarization direction of the incident wave are shown. The crystal manifests its various characteristics in wideband or narrowband reflection and transmission, while absorption remains low. The behaviour of the crystal is determined by its structure geometry yielding excitation of localized plasmons and collective modes together with interactions between them. The optical response of the square lattice structure is also compared with the response of a triangular lattice crystal.

34.Colabella L., Ibarra Pino A.A., Ballarre J., Kowalczyk P., Cisilino A.P., Calculation of cancellous bone elastic properties with the polarization-based FFT iterative scheme, International Journal for Numerical Methods in Biomedical Engineering, ISSN: 2040-7939, DOI: 10.1002/cnm.2879, Vol.33, No.11, pp.e2879-1-16, 2017
Colabella L., Ibarra Pino A.A., Ballarre J., Kowalczyk P., Cisilino A.P., Calculation of cancellous bone elastic properties with the polarization-based FFT iterative scheme, International Journal for Numerical Methods in Biomedical Engineering, ISSN: 2040-7939, DOI: 10.1002/cnm.2879, Vol.33, No.11, pp.e2879-1-16, 2017

Abstract:
The Fast Fourier Transform–based method, originally introduced by Moulinec and Suquet in 1994 has gained popularity for computing homogenized properties of composites. In this work, the method is used for the computational homogenization of the elastic properties of cancellous bone. To the authors' knowledge, this is the first study where the Fast Fourier Transform scheme is applied to bone mechanics. The performance of the method is analyzed for artificial and natural bone samples of 2 species: bovine femoral heads and implanted femurs of Hokkaido rats. Model geometries are constructed using data from X‐ray tomographies, and the bone tissue elastic properties are measured using microindentation and nanoindentation tests. Computed results are in excellent agreement with those available in the literature. The study shows the suitability of the method to accurately estimate the fully anisotropic elastic response of cancellous bone. Guidelines are provided for the construction of the models and the setting of the algorithm.

Keywords:
accelerated FFT method, cancellous bone, homogenized elastic properties

35.Glinicki M.A., Dąbrowski M., Skrzypczyński M., Influence of curing on the properties of air-entrained concrete in the upper layer of exposed aggregate pavement-modelling study, CEMENT, WAPNO, BETON, ISSN: 1425-8129, Vol.XXII/LXXXIV, No.4, pp.271-281, 2017
Glinicki M.A., Dąbrowski M., Skrzypczyński M., Influence of curing on the properties of air-entrained concrete in the upper layer of exposed aggregate pavement-modelling study, CEMENT, WAPNO, BETON, ISSN: 1425-8129, Vol.XXII/LXXXIV, No.4, pp.271-281, 2017

Abstract:
Modelling studies in laboratory of the effect of curing on the mechanical properties and durability of the concrete pavement with exposed aggregate are presented. Air-entrained concrete was designed as the top layer of a motorway pavement with the use of two types of cements: CEM I and CEM III/A. The w/c increase (from 0.34 to 0.37) and change of cement type (CEM I 42.5N and CEM III/A 42.5 N) in properly air-entrained concrete did not influence significantly the internal frost resistance F200 - a decrease of the compressive strength after 200 freeze-thaw cycles was in the range from 4 to 12%. The lowest reduction of strength was observed for concrete with CEM I, w/c=0.34 and proper air entrainment. The properly air-entrained concrete layer with exposed aggregate, which was cured with a curing agent with closure capacity > 85%, was characterized by a very good resistance to surface scaling - the mass of scales m56 was equal to 0.10-0.12 kg/m2, irrespective of the type of cement and w/c ratio. However, there was a significant increase in the water absorption rate, surface scaling and chloride permeability, which caused with inadequate curing

Keywords:
air entrained concrete, curing, durability, exposed aggregate pavement, frost resistance, road pavement, permeability, scaling resistance

36.Levintant Zayonts N., Kwiatkowski L., Swiatek Z., Brzozowska J., Local Pseudoelastic Behaviour and Surface Characteristics of N Ion Implanted NiTi Shape Memory Alloy, ACTA PHYSICA POLONICA A, ISSN: 0587-4246, DOI: 10.12693/APhysPolA.132.210, Vol.132, No.2, pp.210-216, 2017
Levintant Zayonts N., Kwiatkowski L., Swiatek Z., Brzozowska J., Local Pseudoelastic Behaviour and Surface Characteristics of N Ion Implanted NiTi Shape Memory Alloy, ACTA PHYSICA POLONICA A, ISSN: 0587-4246, DOI: 10.12693/APhysPolA.132.210, Vol.132, No.2, pp.210-216, 2017

Abstract:
The main goal of the proposed paper is to present the results of the nitrogen ion implantation effects on mechanical and corrosion properties of NiTi shape memory alloy. Local pseudoelasticity phenomena of NiTi were determined using the ultra-low load applied system. The load–penetration depth curves show that lower nitrogen fluence improves mechanical properties in the near surface layer but higher ion fluence leads to degradation of pseudoelasticity properties. Corrosion resistance of NiTi in the Ringer solution was evaluated by means of electrochemical methods. The results of potentiodynamic measurements in the anodic range for implanted NiTi indicate a decrease of passive current density range in comparison with non-treated NiTi, without any signs related to Ni release. The results of impedance measurements recorded at the corrosion potential show a capacitive behaviour for all samples without clear predominance of one of them. It can be explained by the fact that this result concerns the first stage of corrosion exposition. It is shown that nitrogen ion implantation leads to formation of modified surface of improved physicochemical properties

37.Tauzowski P., Lógó J., Pintér E., Parametric Study on the Element Size Effect for Optimal Topologies, Periodica Polytechnica Civil Engineering, ISSN: 0553-6626, DOI: 10.3311/PPci.0000, pp.1-10, 2017
38.Ustrzycka A., Mróz Z., Kowalewski Z.L., EXPERIMENTAL ANALYSIS AND MODELLING OF FATIGUE CRACK INITIATION MECHANISMS, JOURNAL OF THEORETICAL AND APPLIED MECHANICS, ISSN: 1429-2955, DOI: 10.15632/jtam-pl.55.4.1443, Vol.55, No.4, pp.1443-1448, 2017
Ustrzycka A., Mróz Z., Kowalewski Z.L., EXPERIMENTAL ANALYSIS AND MODELLING OF FATIGUE CRACK INITIATION MECHANISMS, JOURNAL OF THEORETICAL AND APPLIED MECHANICS, ISSN: 1429-2955, DOI: 10.15632/jtam-pl.55.4.1443, Vol.55, No.4, pp.1443-1448, 2017

Abstract:
The present work is devoted to simulation of fatigue crack initiation for cyclic loading within the nominal elastic regime. It is assumed that damage growth occurs due to action of meanstress and its fluctuations induced by crystalline grain inhomogeneity and the free boundary effect. The macrocrack initiation corresponds to a critical value of accumulated damage. The modelling of damage growth is supported by Electronic Speckle Pattern Interferometry (ESPI) apparatus using coherent laser light.

Keywords:
fatigue crack initiation, damage evolution, optical methods

39.Będkowski J., Röhling T., Hoeller F., Shulz D., Schneider F.E., Benchmark of 6D SLAM (6D Simultaneous Localisation and Mapping) Algorithms with Robotic Mobile Mapping Systems, Foundations of Computing and Decision Sciences, ISSN: 0867-6356, DOI: 10.1515/fcds-2017-0014, Vol.42, No.3, pp.275-295, 2017
Będkowski J., Röhling T., Hoeller F., Shulz D., Schneider F.E., Benchmark of 6D SLAM (6D Simultaneous Localisation and Mapping) Algorithms with Robotic Mobile Mapping Systems, Foundations of Computing and Decision Sciences, ISSN: 0867-6356, DOI: 10.1515/fcds-2017-0014, Vol.42, No.3, pp.275-295, 2017

Abstract:
This work concerns the study of 6DSLAM algorithms with an application of robotic mobile mapping systems. The architecture of the 6DSLAM algorithm is designed for evaluation of different data registration strategies. The algorithm is composed of the iterative registration component, thus ICP (Iterative Closest Point), ICP (point to projection), ICP with semantic discrimination of points, LS3D (Least Square Surface Matching), NDT (Normal Distribution Transform) can be chosen. Loop closing is based on LUM and LS3D. The main research goal was to investigate the semantic discrimination of measured points that improve the accuracy of final map especially in demanding scenarios such as multi-level maps (e.g., climbing stairs). The parallel programming based nearest neighborhood search implementation such as point to point, point to projection, semantic discrimination of points is used. The 6DSLAM framework is based on modified 3DTK and PCL open source libraries and parallel programming techniques using NVIDIA CUDA. The paper shows experiments that are demonstrating advantages of proposed approach in relation to practical applications. The major added value of presented research is the qualitative and quantitative evaluation based on realistic scenarios including ground truth data obtained by geodetic survey. The research novelty looking from mobile robotics is the evaluation of LS3D algorithm well known in geodesy.

Keywords:
Mobile robot, Mobile mapping system, Iterative Closest Point, Least Square Surface Matching, Normal Distribution Transform, LUM, 6DSLAM, CUDA

40.Będkowski J., Röhling T., Online 3D LIDAR Monte Carlo localization with GPU acceleration, Industrial Robot: An International Journal, ISSN: 0143-991X, DOI: 10.1108/IR-11-2016-0309, Vol.44, No.4, pp.442-456, 2017
Będkowski J., Röhling T., Online 3D LIDAR Monte Carlo localization with GPU acceleration, Industrial Robot: An International Journal, ISSN: 0143-991X, DOI: 10.1108/IR-11-2016-0309, Vol.44, No.4, pp.442-456, 2017

Abstract:
*Purpose*

This paper aims to focus on real-world mobile systems, and thus propose relevant contribution to the special issue on “Real-world mobile robot systems”. This work on 3D laser semantic mobile mapping and particle filter localization dedicated for robot patrolling urban sites is elaborated with a focus on parallel computing application for semantic mapping and particle filter localization. The real robotic application of patrolling urban sites is the goal; thus, it has been shown that crucial robotic components have reach high Technology Readiness Level (TRL).

*Design/methodology/approach*

Three different robotic platforms equipped with different 3D laser measurement system were compared. Each system provides different data according to the measured distance, density of points and noise; thus, the influence of data into final semantic maps has been compared. The realistic problem is to use these semantic maps for robot localization; thus, the influence of different maps into particle filter localization has been elaborated. A new approach has been proposed for particle filter localization based on 3D semantic information, and thus, the behavior of particle filter in different realistic conditions has been elaborated. The process of using proposed robotic components for patrolling urban site, such as the robot checking geometrical changes of the environment, has been detailed.

*Findings*

The focus on real-world mobile systems requires different points of view for scientific work. This study is focused on robust and reliable solutions that could be integrated with real applications. Thus, new parallel computing approach for semantic mapping and particle filter localization has been proposed. Based on the literature, semantic 3D particle filter localization has not yet been elaborated; thus, innovative solutions for solving this issue have been proposed. Recently, a semantic mapping framework that was already published was developed. For this reason, this study claimed that the authors’ applied studies during real-world trials with such mapping system are added value relevant for this special issue.

*Research limitations/implications*

The main problem is the compromise between computer power and energy consumed by heavy calculations, thus our main focus is to use modern GPGPU, NVIDIA PASCAL parallel processor architecture. Recent advances in GPGPUs shows great potency for mobile robotic applications, thus this study is focused on increasing mapping and localization capabilities by improving the algorithms. Current limitation is related with the number of particles processed by a single processor, and thus achieved performance of 500 particles in real-time is the current limitation. The implication is that multi-GPU architectures for increasing the number of processed particle can be used. Thus, further studies are required.

*Practical implications*

The research focus is related to real-world mobile systems; thus, practical aspects of the work are crucial. The main practical application is semantic mapping that could be used for many robotic applications. The authors claim that their particle filter localization is ready to integrate with real robotic platforms using modern 3D laser measurement system. For this reason, the authors claim that their system can improve existing autonomous robotic platforms. The proposed components can be used for detection of geometrical changes in the scene; thus, many practical functionalities can be applied such as: detection of cars, detection of opened/closed gate, etc. […] These functionalities are crucial elements of the safe and security domain.

*Social implications*

Improvement of safe and security domain is a crucial aspect of modern society. Protecting critical infrastructure plays an important role, thus introducing autonomous mobile platforms capable of supporting human operators of safe and security systems could have a positive impact if viewed from many points of view.

*Originality/value*

This study elaborates the novel approach of particle filter localization based on 3D data and semantic mapping. This original work could have a great impact on the mobile robotics domain, and thus, this study claims that many algorithmic and implementation issues were solved assuming real-task experiments. The originality of this work is influenced by the use of modern advanced robotic systems being a relevant set of technologies for proper evaluation of the proposed approach. Such a combination of experimental hardware and original algorithms and implementation is definitely an added value.

Keywords:
3D laser, Monte Carlo localization, Parallel computing, Particle filter localization, Semantic mapping, Unmanned ground vehicle

41.Wencel A., Zakrzewska K.E., Samluk A., Noszczyk B.H., Pijanowska D.G., Pluta K.D., Dried human skin fibroblasts as a new substratum for functional culture of hepatic cells, ACTA BIOCHIMICA POLONICA, ISSN: 0001-527X, DOI: 10.18388/abp.2016_1481, Vol.64, No.2, pp.357-363, 2017
Wencel A., Zakrzewska K.E., Samluk A., Noszczyk B.H., Pijanowska D.G., Pluta K.D., Dried human skin fibroblasts as a new substratum for functional culture of hepatic cells, ACTA BIOCHIMICA POLONICA, ISSN: 0001-527X, DOI: 10.18388/abp.2016_1481, Vol.64, No.2, pp.357-363, 2017

Abstract:
The primary hepatocytes culture is still one of the main challenges in toxicology studies in the drug discovery process, development of in vitro models to study liver function, and cell-based therapies. Isolated hepatocytes display a rapid decline in viability and liver-specific functions including albumin production, conversion of ammonia to urea, and activity of the drug metabolizing enzymes. A number of methods have been developed in order to maintain hepatocytes in their highly differentiated state in vitro. Optimization of culture conditions includes a variety of media formulations and supplements, growth surface coating with the components of extracellular matrix or with synthetic polymers, three-dimensional growth scaffolds and decellularized tissues, and coculture with other cell types required for the normal cell-cell interactions. Here we propose a new substratum for hepatic cells made by drying confluent human skin fibroblasts’ culture. This growth surface coating, prepared using maximally simplified procedure, combines the advantages of the use of extracellular matrices and growth factors/cytokines secreted by the feeder layer cells. In comparison to the hepatoma cells grown on a regular tissue culture plastic, cells cultured on the dried fibroblasts were able to synthesize albumin in larger quantities and to form greater number of apical vacuoles. Unlike the coculture with the living feeder layer cells, the number of cells grown on the new substratum was not reduced after fourteen days of culture. This fact could make the dried fibroblasts coating an ideal candidate for the substrate for non-dividing human hepatocytes.

Keywords:
cocultures, culture substratum, dried fibroblasts, human skin fibroblasts, C3A cells

42.Jóźwiak-Niedźwiedzka D., Gibas K., Glinicki M.A., PETROGRAPHIC IDENTIFICATION OF REACTIVE MINERALS IN DOMESTIC AGGREGATES AND THEIR CLASSIFICATION ACCORDING TO RILEM AND ASTM RECOMMENDATIONS, Roads and Bridges - Drogi i Mosty, ISSN: 1643-1618, DOI: 10.7409/rabdim.017.015, Vol.16, pp.223-239, 2017
Jóźwiak-Niedźwiedzka D., Gibas K., Glinicki M.A., PETROGRAPHIC IDENTIFICATION OF REACTIVE MINERALS IN DOMESTIC AGGREGATES AND THEIR CLASSIFICATION ACCORDING TO RILEM AND ASTM RECOMMENDATIONS, Roads and Bridges - Drogi i Mosty, ISSN: 1643-1618, DOI: 10.7409/rabdim.017.015, Vol.16, pp.223-239, 2017

Abstract:
Considering the long-time durability of concrete in road infrastructure it is important to control the threat of expansive reaction between sodium and potassium hydroxides in the pore solution and the reactive minerals present in the aggregate. Petrographic analysis is the basis for the qualification of aggregates to appropriate classes of reactivity according to ASTM C1778 and RILEM recommendations. This paper presents the results of petrographic analyses of thin sections made from twenty different domestic aggregates. The tested crushed aggregates were obtained from bedrock and glacial deposits. The evaluation of the mineral composition of aggregates included identification of deleterious components and determination of the content of reactive forms of silica. This enabled preliminary classification of aggregate in one of the three classes of reactivity according to RILEM. Obtained results provide an initial assessment of potential reactivity of aggregates and can assist in making decisions to undertake further accelerated or long-term laboratory testing or to modify the concrete mix design.

Keywords:
aggregate, alkali-aggregate reaction (AAR), petrographic analysis, reactive minerals, thin sections

43.Frąś T., Frąś L.J., Faderl N., RUBBER AND MAGNETORHEOLOGICAL FLUID APPLIED AS THE INTERLAYER IN COMPOSITE ARMOURS AGAINST HIGH-VELOCITY LOADINGS, DIAGNOSTYKA, ISSN: 1641-6414, Vol.18, No.3, pp.63-68, 2017
Frąś T., Frąś L.J., Faderl N., RUBBER AND MAGNETORHEOLOGICAL FLUID APPLIED AS THE INTERLAYER IN COMPOSITE ARMOURS AGAINST HIGH-VELOCITY LOADINGS, DIAGNOSTYKA, ISSN: 1641-6414, Vol.18, No.3, pp.63-68, 2017

Abstract:
Monolithic, homogenous ballistic shields consisting of a single thick, high-hardness and high-strength steel plate are rarely applied in modern combat vehicles. Currently, a popular armour concept is a multilayered shield since it is expected that the kinetic energy of a threat may be dissipated by transmission through materials with different properties and also by multiple interface reflections. Searching for a maximum ballistic protection at minimum weight inspires applications of various materials which complementary behaviour provides a high protective efficiency without excessive mass. The preliminary experimental investigation presented in the paper aimed to verify behaviour of two prototyped laminated armours under impacts of small-calibre projectiles (cal. 7.62). The main interest lied in impact properties of materials proposed as the intermediate layer. The first tested concept was a laminated steel armour with the 10 mm thick rubber interlayer. In the second armour, the intermediate layer consisted of a magnetorheological fluid.

Keywords:
energy absorption, rubber, magnetorheological fluid, protective properties

44.Widłaszewski J., Nowak M., Nowak Z., Kurp P., Laser-assisted forming of thin-walled profiles, Metal Forming, ISSN: 0867-2628, Vol.XXVIII, No.3, pp.183-198, 2017
Widłaszewski J., Nowak M., Nowak Z., Kurp P., Laser-assisted forming of thin-walled profiles, Metal Forming, ISSN: 0867-2628, Vol.XXVIII, No.3, pp.183-198, 2017

Abstract:
Forming processes assisted by localised laser heating are studied in recent years. Heating is used to make it possible or facilitate forming of materials, which exhibit such adverse properties as: brittleness, effects of high work-hardening or a high elastic springback. The hereby presented investigations concern the hybrid thermo-mechanical forming of thin-walled parts using local heating of the material by the laser beam. The research is aimed at forming of parts from materials used in the aviation industry, such as the nickel-base super-alloys Inconel 625, Inconel 718, and also martensitic superalloys AISI 410 and AISI 325. Preliminary investigations are conducted using X5CrNil8-10 (1.4301) stainless steel. Experimental study and numerical simulations cover the behaviour of thin beams 1 mm thick, subjected to mechanical load in the cantilever arrangement and heated by the CO2 laser beam moving from the free end of the sample towards its fixture. The possibility of obtaining large bending deformations relatively easily due to the application of laser beam is demonstrated experimentally. Experimentally verified finite element numerical simulations show the intense plastic flow of the material layer heated by the laser beam. It is accompanied by a shift of the cross-section neutral axis of the beam. Bending of thin-walled tubes in a specially designed device is studied in the next step. It allows introducing mechanical loading in a controlled manner, heating the material by a moving laser beam and forcing the required deformation according to the kinematic scheme of the device.

Keywords:
laser-assisted forming, finite element method, thin-walled structure

45.Fryczowski K., Roskosz M., Kukla D., Szwed M., Wykorzystanie szumu Barkhausena w ocenie twardości warstw nawęglanych oraz hartowanych indukcyjnie na stali AMS 6414, PRZEGLĄD SPAWALNICTWA, ISSN: 0033-2364, Vol.89, No.11, pp.1-6, 2017
Fryczowski K., Roskosz M., Kukla D., Szwed M., Wykorzystanie szumu Barkhausena w ocenie twardości warstw nawęglanych oraz hartowanych indukcyjnie na stali AMS 6414, PRZEGLĄD SPAWALNICTWA, ISSN: 0033-2364, Vol.89, No.11, pp.1-6, 2017

Abstract:
Analizowano możliwości określenia zmian twardości warstw nawęglanych i hartowanych indukcyjnie na podstawie wielkości ilościowo opisujących szum Barkhausena. Badania przeprowadzono na zestawie trzech próbek o stałej grubości warstwy nawęglanej (1,2 mm) o różnych wartościach twardości. Pomiary przeprowadzono dla trzech konfiguracji aparatury MEB-4C Mag-Lab s.c. różniących się częstotliwością prądu magnesującego. Analizowano obwiednię szumu Barkhausena i jej punkty charakterystyczne, energię, RMS, periodogramy FFT oraz rozkłady liczby zdarzeń. Uzyskano interesujące korelacje diagnostyczne mogące posłużyć w rozwiązywaniu zagadnień odwrotnych badań nieniszczących

Keywords:
twardość, szum Barkhausena, zagadnienie odwrotne

46.Szymczak T., Kowalewski Z.L., WYBRANE MATERIAŁY STOSOWANE W UKŁADACH HAMULCOWYCH I ICH WŁAŚCIWOŚCI MECHANICZNE, TRANSPORT SAMOCHODOWY, ISSN: 1731-2795, Vol.2, pp.87-99, 2017
Szymczak T., Kowalewski Z.L., WYBRANE MATERIAŁY STOSOWANE W UKŁADACH HAMULCOWYCH I ICH WŁAŚCIWOŚCI MECHANICZNE, TRANSPORT SAMOCHODOWY, ISSN: 1731-2795, Vol.2, pp.87-99, 2017

Abstract:
W pracy omówiono wybrane materiały stosowane w układach hamulcowych, jak: żeliwo szare, kompozyty ceramiczne oraz metalowe o osnowie ze stopu aluminium. Zaprezentowano ich zasadnicze właściwości mechaniczne oraz parametry fizyczne. Ponadto, omówiono zmiany granicy plastyczności i wytrzymałości doraźnej żeliwa szarego w warunkach rozciągania prowadzonego przy dziewięciu poziomach temperatury w zakresie od 20 °C do 700 °C

47.Wasilewski M., Pisarski D., Adaptive optimal control algorithm for vibrational systems under nonlinear friction, MMAR 2017, 22nd International Conference on Methods and Models in Automation and Robotics, 2017-08-28/08-31, Międzyzdroje (PL), pp.107-112, 2017
Wasilewski M., Pisarski D., Adaptive optimal control algorithm for vibrational systems under nonlinear friction, MMAR 2017, 22nd International Conference on Methods and Models in Automation and Robotics, 2017-08-28/08-31, Międzyzdroje (PL), pp.107-112, 2017

Abstract:
In this paper, a novel control algorithm for vibration attenuation is presented. The proposed scheme is developed to control linear systems with a presence of an external disturbance. The goal of the control is to steer the system to prescribed reference trajectory by minimizing associated quadratic performance index.
The synthesis of the control law consists of two steps. At the first step, past measures of disturbance are used to develop a local linear approximation of dynamics of the disturbance signal. Weights of the associated auto-regressive model are calculated by the least-square algorithm. At the second step, the calculated model is used to obtain a linear time-invariant approximation of the control system. The receding horizon control law is then calculated by using finite horizon Linear Quadratic Regulator. The algorithm is verified numerically for a torsional vibrating system under nonlinear, time-varying friction. The results of the simulation are compared to a standard Linear Quadratic Gaussian control.

48.Wasilewski M., Pisarski D., Konowrocki R., Bajer C.I., New efficient adaptive control of torsional vibrations induced by sudden nonlinear disturbances, CMM-2017, 22nd International Conference on Computer Methods in Mechanics, 2017-09-13/09-16, Lublin (PL), pp.1-2, 2017
Wasilewski M., Pisarski D., Konowrocki R., Bajer C.I., New efficient adaptive control of torsional vibrations induced by sudden nonlinear disturbances, CMM-2017, 22nd International Conference on Computer Methods in Mechanics, 2017-09-13/09-16, Lublin (PL), pp.1-2, 2017

Abstract:
The aim of this paper is to present a novel adaptive technique of control of the vibrating drilling systems. The algorithm constitutes an adaptive linear quadratic regulator that uses direct measurements of the disturbance to synthesize its linear dynamic approximation. This approach allows generating control law that includes the impact of the friction on the system dynamics and optimally steers the system to the desired trajectory. The effectiveness of the algorithm is validated via comprehensive numerical simulations of the control of the simplified drilling model. The results are compared to these obtained with the use of the Linear Quadratic Gaussian regulator.

Keywords:
vibration control, drillstring, adaptive control, auto-regressive model

49.Lumelskyj D., Rojek J., Banabic D., Lazarescu L., Detection of Strain Localization in Nakazima Formability Test - Experimental Research and Numerical Simulation, SHEMET17, 17th International Conference on Sheet Metal, 2017-04-10/04-12, Palermo (IT), DOI: 10.1016/j.proeng.2017.04.016, No.183, pp.89-94, 2017
Lumelskyj D., Rojek J., Banabic D., Lazarescu L., Detection of Strain Localization in Nakazima Formability Test - Experimental Research and Numerical Simulation, SHEMET17, 17th International Conference on Sheet Metal, 2017-04-10/04-12, Palermo (IT), DOI: 10.1016/j.proeng.2017.04.016, No.183, pp.89-94, 2017

Abstract:
This paper presents the investigation on detection of strain localization in experimental research and numerical simulation of sheet metal forming. Experimental tests and numerical simulations of the Nakazima test have been performed for the DC04 grade steel sheet. 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 evaluated by the maximum of strain acceleration which corresponds to the inflection point of the strain velocity vs. time. The limit strains have been calculated numerically and experimentally for specimens undergoing deformation at different strain paths. It has been shown that the numerical model predicts formability limits close to the experimental results. Analyzed criterion 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

50.Jurczak G., Maździarz M., Dłużewski P., Finite element modelling of threading dislocation effect on GaN/AlN quantum dot, ICMM5, 5th International Conference on Material Modeling, 2017-06-14/06-16, Rome (IT), pp.1-1, 2017
Jurczak G., Maździarz M., Dłużewski P., Finite element modelling of threading dislocation effect on GaN/AlN quantum dot, ICMM5, 5th International Conference on Material Modeling, 2017-06-14/06-16, Rome (IT), pp.1-1, 2017

Keywords:
Quantum dot, Threading dislocation, Piezoelectricity, Finite element modelling

51.Wawrzyk K., Nosewicz S., Rojek J., Kowalczyk P., A constitutive model and numerical simulation of sintering processes at macroscopic level, CMM-2017, 22nd International Conference on Computer Methods in Mechanics, 2017-09-13/09-16, Lublin (PL), pp.MS02-13-MS02-14, 2017
Wawrzyk K., Nosewicz S., Rojek J., Kowalczyk P., A constitutive model and numerical simulation of sintering processes at macroscopic level, CMM-2017, 22nd International Conference on Computer Methods in Mechanics, 2017-09-13/09-16, Lublin (PL), pp.MS02-13-MS02-14, 2017

Abstract:
This document presents modelling of single-phase powder sintering processes at the macroscopic level. In particular, its constitutive formulation, numerical implementation and numerical test are described. Numerical tests were carried out for a cylindrical specimen under hydrostatic and uniaxial pressure. Results of macroscopic analysis are compared against the microscopic model results.

Keywords:
sintering porcesses, numerical analysis, multiscale modelling

52.Rojek J., Zubelewicz A., Madan N., Nosewicz S., New formulation of the discrete element method, CMM-2017, 22nd International Conference on Computer Methods in Mechanics, 2017-09-13/09-16, Lublin (PL), pp.MS13-27-MS13-28, 2017
Rojek J., Zubelewicz A., Madan N., Nosewicz S., New formulation of the discrete element method, CMM-2017, 22nd International Conference on Computer Methods in Mechanics, 2017-09-13/09-16, Lublin (PL), pp.MS13-27-MS13-28, 2017

Abstract:
This work presents a new original formulation of the discrete element method based on the soft contact approach. The standard DEM has been enhanced by introduction of the additional (global) deformation mode caused by the stresses in the particles induced by the contact forces. Uniform stresses and strains are assumed for each particle. The stresses are calculated from the contact forces. The strains are obtained using an inverse constitutive relationship. The strains allow us to obtain deformed particle shapes. The deformed shapes (ellipses) are taken into account in contact detection and evaluation of the contact forces. The numerical example shows that a particle deformation changes the particle interaction and the distribution of forces in the discrete element assembly.

Keywords:
discrete element method; deformable particles; soft contact

53.Mrozek A., Kuś W., Burczyński T., Modelling of molybdenum-based 2D materials , CMM-2017, 22nd International Conference on Computer Methods in Mechanics, 2017-09-13/09-16, Lublin (PL), pp.MS14-27-MS14-28, 2017
Mrozek A., Kuś W., Burczyński T., Modelling of molybdenum-based 2D materials , CMM-2017, 22nd International Conference on Computer Methods in Mechanics, 2017-09-13/09-16, Lublin (PL), pp.MS14-27-MS14-28, 2017

Abstract:
The flat, two dimensional materials play important role in the research and industrial applications in the last 15 years. The new materials with flat atomic structures are discovered every month. The focus of the paper is on the modelling of the single layer molybdenum disulphide based material. The numerical simulations and mechanical material properties are described and discussed.

Keywords:
molybdenum, two dimensional materials, molecular modelling, MoS2

54.Leyva-Mendivil M.F., Lengiewicz J., Page A., Bressloff N.W., Limbert G., Implications of Multi-asperity Contact for Shear Stress Distribution in the Viable Epidermis – An Image-based Finite Element Study, BIOTRIBOLOGY, ISSN: 2352-5738, DOI: 10.1016/j.biotri.2017.04.001, Vol.11, pp.110-123, 2017
Leyva-Mendivil M.F., Lengiewicz J., Page A., Bressloff N.W., Limbert G., Implications of Multi-asperity Contact for Shear Stress Distribution in the Viable Epidermis – An Image-based Finite Element Study, BIOTRIBOLOGY, ISSN: 2352-5738, DOI: 10.1016/j.biotri.2017.04.001, Vol.11, pp.110-123, 2017

Abstract:
Understanding load transfer mechanisms from the surface of the skin to its deeper layers is crucial in gaining a fundamental insight into damage phenomena related to skin tears, blisters and superficial/deep tissue ulcers. It is unknown how shear stresses in the viable epidermis are conditioned by the skin surface topography and internal microstructure and to which extent their propagation is conditioned by the size of a contacting asperities. In this computational study, these questions were addressed by conducting a series of contact finite element analyses simulating normal indentation of an anatomically-based two-dimensional multi-layer model of the skin by rigid indenters of various sizes and sliding of these indenters over the skin surface. Indentation depths, local (i.e. microscopic) coefficients of friction and Young's modulus of the stratum corneum were also varied. For comparison purpose and for isolating effects arising purely from the skin microstructure, a geometrically-idealised equivalent multi-layer model of the skin was also considered. The multi-asperity contact induced by the skin topographic features in combination with a non-idealised geometry of the skin layers lead to levels of shear stresses much higher than those produced in the geometrically-idealised case. These effects are also modulated by other system parameters (e.g. local coefficient of friction, indenter radius). These findings have major implications for the design and analyses of finite element studies aiming at modelling the tribology of skin, particularly if the focus is on how surface shear stress leads to damage initiation which is a process known to occur across several length scales.

Keywords:
Skin, Microstructure, Contact mechanics, Indentation, Sliding contact, Finite element, Image-based modelling, Material properties

55.Szolc T., Konowrocki R., Pochanke A., Michajłow M., Dynamic aspects of design and maintenance of the rotating machinery applied in the mining industry, MEC-2017, MINERAL ENGINEERING CONFERENCE, 2017-09-20/09-23, Wisła (PL), No.2, pp.14-15, 2017
Szolc T., Konowrocki R., Pochanke A., Michajłow M., Dynamic aspects of design and maintenance of the rotating machinery applied in the mining industry, MEC-2017, MINERAL ENGINEERING CONFERENCE, 2017-09-20/09-23, Wisła (PL), No.2, pp.14-15, 2017

Abstract:
In the paper a dynamic behaviour of the selected typical group of rotating machines applied in the mining industry is investigated. These are the beater mills and crushers as well as blowers and compressors, all driven by the asynchronous motors. In particular, there is considered an influence of various types of machine working tool loadings on the system lateral steady-state dynamic responses as well as a mutual torsional electromechanical interaction between the driving motor and the driven machine in transient operational conditions. The theoretical calculations have been performed by means of the advanced structural mechanical models. The conclusions drawn from computational results can be very useful during design phase of these devices as well as helpful for their users during regular maintenance.

Keywords:
rotating mill machinery, electric motor interaction, electromechanical model, torsion vibration

56.Pisarski D., Myśliński A., Online adaptive semi-active vibration damping of slender structures subject to moving loads, ICOEV2017, International Conference on Engineering Vibration, 2017-09-04/09-07, Sofia (BG), pp.1, 2017
Pisarski D., Myśliński A., Online adaptive semi-active vibration damping of slender structures subject to moving loads, ICOEV2017, International Conference on Engineering Vibration, 2017-09-04/09-07, Sofia (BG), pp.1, 2017

Abstract:
In this paper, the problem of the optimal control of a structure subjected to a moving load has been studied. In contrast to the previous works of the authors, focused on open-loop strategies, this paper has been devoted to an adaptive closed-loop control, where the switched damping strategy is subject to real-time adaptation according to the measured speed of the moving load.
The proposed adaptive controller has been designed based on the use of the reference optimal solutions computed for a given constant velocity and a set of functions describing the sensitivity of the system dynamics to a change in the speed and the initial state. All these data are pre-computed offline and stored in the controller's memory. As a result, the online computational algorithm, based on a simple gradient descent loop, uses a minimal calculation effort. This allows almost immediate updating of the optimal controls, even with the use of a standard PC. The method has been validated by means of numerical experiments carried out for a wide range of the velocity perturbation scenarios. The proposed scheme is general for a class of time-varying bilinear control systems and can be implemented to a wide range of problems concerned with smart structural elements.

57.Chudzikiewicz A., Bogacz R., Kostrzewski M., Konowrocki R., Condition monitoring of railway track systems by using acceleration signals on wheelset axle-boxes, Transport, ISSN: 1648-4142, DOI: 10.3846/16484142.2017.1342101, pp.1-12, 2017
Chudzikiewicz A., Bogacz R., Kostrzewski M., Konowrocki R., Condition monitoring of railway track systems by using acceleration signals on wheelset axle-boxes, Transport, ISSN: 1648-4142, DOI: 10.3846/16484142.2017.1342101, pp.1-12, 2017

Abstract:
The aim of this paper is to demonstrate the possibilities of estimating the track condition using axle-boxes and car-bodies motions described by acceleration signals. In the paper, the results presented indicate the condition of tracks obtained from the preliminary investigation on the test track. Furthermore, the results from the supervised runs (on Polish Railway Lines) of electric multiple unit (EMU-ED74) with the prototype of track quality monitoring system installed on-board are described. As track quality indicator (TQI) algorithm, used in the mentioned prototype, a modified Karhunen–Loève transformation is used in preliminary preparing acceleration signals. The transformation is used to extract the principal dynamics from measurement data. Obtained results are compared to other methods of evaluating the geometrical track quality, namely methods which apply the Jsynth Synthetic Coefficient and Five Parameters of Defectiveness W5. The results from the investigation showed that track condition estimation is possible with acceptable accuracy for in-service use and for defining cost-effective maintenance strategies.

Keywords:
railway track monitoring, wheel–rail interaction, track quality indicator, acceleration signals, experimental investigation, track degradation.

58.Mackiewicz S., PODSTAWOWE ZASADY PRZEPROWADZANIA EKSPOZYCJI RADIOGRAFICZNYCH NA PANELACH PŁASKICH, Stary Młyn 2017, KRAJOWA KONFERENCJA BADAŃ RADIOGRAFICZNYCH, 2017-09-04/09-06, Bolesławiec k/Wieruszowa (PL), pp.15-26, 2017
59.Mackiewicz S., Detektory promieniowania stosowane w cyfrowej radiografii bezpośredniej, BADANIA NIENISZCZĄCE I DIAGNOSTYKA, ISSN: 2451-4462, Vol.1-2, pp.44-51, 2017
Mackiewicz S., Detektory promieniowania stosowane w cyfrowej radiografii bezpośredniej, BADANIA NIENISZCZĄCE I DIAGNOSTYKA, ISSN: 2451-4462, Vol.1-2, pp.44-51, 2017

Abstract:
W artykule opisano podstawy działania detektorów promieniowania stosowanych w cyfrowej radiografii bezpośredniej - DR . Scharakteryzowano rożne rodzaje paneli płaskich pod kątem ich przydatności w obszarze badań nieniszczących. W sposób bardziej szczegółowy omówiono panele płaskie z przemianą pośrednią oparte na matrycy a-Si z tranzystorami TFT, które wykazują obecnie największą przydatność do zastosowań w badaniach nieniszczących. Przeanalizowano najważniejsze parametry paneli płaskich w aspekcie ich zastosowań do badań złączy spawanych oraz innych wyrobów i elementów badanych dotychczas tradycyjną metodą radiograficzną

Keywords:
radiografia cyfrowa, panele płaskie, radiografia bezpośrednia DR

60.Pisarski D., Szmidt T., Semi-Active Stabilization of Pipe Discharging Air With Electromagnetic Devices of Motional Type, ICAST2017, The 28th International Conference on Adaptive Structures and Technologies, 2017-10-08/10-11, Kraków (PL), pp.1-1, 2017
Pisarski D., Szmidt T., Semi-Active Stabilization of Pipe Discharging Air With Electromagnetic Devices of Motional Type, ICAST2017, The 28th International Conference on Adaptive Structures and Technologies, 2017-10-08/10-11, Kraków (PL), pp.1-1, 2017

Abstract:
The study deals with a problem of applying electromagnetic devices of motional type to improve the dynamic stability of a pipe conveying air. When the flow velocity reaches its critical value the steady equilibrium position becomes unstable, and self-excited lateral vibrations arise. Electromagnetic devices of another – transformer – type demonstrated to have been highly effective in the passive stabilization of such system as well as active stabilization of similar non-conservative system with a follower force. In the present work, we apply a pair of motional devices made of a conducting plate which is attached to the pipe and moves together with it within the perpendicular magnetic field generated by the controlled electromagnets. This motion generates eddy currents in the plates and a drag force of a viscous character. Under this setting, we firstly investigate the possibility of designing a stabilizing control within the magnetic field’s region where every passive solution results in an unstable or conservative state. For that purpose, we constitute a practical condition justifying the existence of a stabilizing control for a given set of system parameters. Later we pose and solve an optimal control problem aiming at stabilizing the system with the optimal rates of decrease of the system’s energy. The solution is examined by means of numerical simulations performed within the three regions of the flow velocity: low subcritical where the Coriolis acceleration of the conveyed fluid generates the predominate damping force, high subcritical where the inertia of the fluid begins to dominate dynamics of the system, and low supercritical where unstable flutter vibrations start to arise. The effectiveness of the designed optimal controller is validated by comparisons with the corresponding passive solutions.

61.Długosz A., Pokorska I., Glinicki M.A., Jaskulski R., Identification of thermal properties of hardening concrete by means of evolutionary algorithms, ECCOMAS - IPM 2017, 4th International Conference on Inverse Problems in Mechanics of Structures and Materials, 2017-05-31/06-02, Rzeszów - Krasiczyn (PL), pp.17-18, 2017
62.Kurtis K.E., Xi Y., Glinicki M.A., Provis J., Giannini E.R., Fu T., Can We Design Concrete to Survive Nuclear Environments?, CONCRETE INTERNATIONAL, ISSN: 0162-4075, Vol.39, No.11, pp.53-59, 2017
63.Nowak Z., Nowak M., Widłaszewski J., Kurp P., Experimental and numerical investigation on laser-assisted bending of pre-loaded metal plate, CMM-2017, 22nd International Conference on Computer Methods in Mechanics, 2017-09-13/09-16, Lublin (PL), No.MS13, pp.37-38, 2017
Nowak Z., Nowak M., Widłaszewski J., Kurp P., Experimental and numerical investigation on laser-assisted bending of pre-loaded metal plate, CMM-2017, 22nd International Conference on Computer Methods in Mechanics, 2017-09-13/09-16, Lublin (PL), No.MS13, pp.37-38, 2017

Abstract:
The laser forming technique has an important disadvantage, which is the limitation of plastic deformation generated by a single laser beam pass. In order to increase the plastic deformation one has to repeat the process several times or use the alternative method. To increase the plastic deformation it is possible to add external forces during the laser forming process. In this paper, we investigate the influence of external pre-loads on the laser bending of steel plate. The pre-loads investigated generate bending towards the laser beam. The thermal, elastic-plastic analysis is performed using the commercial nonlinear finite element analysis package ABAQUS. The focus of the paper is to identify how this pattern of the pre-load influence the final bend angle of the plate.

Keywords:
laser forming, force-assisted laser bending, thermo-mechanical simulations, FEA

64.Szolc T., Konowrocki R., Pochanke A., Michajłow M., Dynamic aspects of design and maintenance of the rotating machinery applied by the mining industry , MEC-2017, MINERAL ENGINEERING CONFERENCE, 2017-09-20/09-23, Wisła (PL), DOI: 10.1051/e3sconf/201712301010, No.18, 01010, pp.1-10, 2017
Szolc T., Konowrocki R., Pochanke A., Michajłow M., Dynamic aspects of design and maintenance of the rotating machinery applied by the mining industry , MEC-2017, MINERAL ENGINEERING CONFERENCE, 2017-09-20/09-23, Wisła (PL), DOI: 10.1051/e3sconf/201712301010, No.18, 01010, pp.1-10, 2017

Abstract:
In the paper a dynamic behaviour of the selected typical group of rotating machines applied in the mining industry is investigated. These are the beater mills and crushers as well as blowers and compressors, all driven by the asynchronous motors. In particular, there is considered an influence of various types of machine working tool loadings on the system lateral steady-state dynamic responses as well as a mutual torsional electromechanical interaction between the driving motor and the driven machine in transient operational conditions. The theoretical calculations have been performed by means of the advanced structural mechanical models. The conclusions drawn from computational results can be very useful during design phase of these devices as well as helpful for their users during regular maintenance.

Keywords:
mining industry, electromechanic coupling, design and maintenance of mill, torsional vibrations

65.Katz T., SPRAWDZANIE I WERYFIKACJA KLASYCZNYCH DEFEKTOSKOPÓW ULTRADŹWIĘKOWYCH, XXIII Seminarium NIENISZCZĄCE BADANIA MATERIAŁÓW, 2017-03-15/03-17, Zakopane (PL), pp.161-169, 2017
66.Katz T., Characterization and verification of ultrasonic flaw detector, 46. KKBN, 46. Krajowa Konferencja Badań Nieniszczących, 2017-10-17/10-19, Starachowice (PL), pp.29-32, 2017
Katz T., Characterization and verification of ultrasonic flaw detector, 46. KKBN, 46. Krajowa Konferencja Badań Nieniszczących, 2017-10-17/10-19, Starachowice (PL), pp.29-32, 2017

Abstract:
The purpose of this article is to present the most important requirements and problems related to periodic inspection of ultrasonic flaw detectors in accordance with requirements of standard PN-EN12668-1: 2010. Particular attention has been paid to the measurement of ultrasonic flaw detector parameters and requirements concerning specialist measuring equipment. The form of ultrasonic flaw detector certificate was proposed, which specifies all tests of group 2 of PN-EN12668-1: 2010. The proposed certificate confirms the compatibility of the flaw detector with the speci­fied standard and the test group under which the equipment was tested.

Keywords:
characterization, verification, calibration, flaw, detector

67.Popławski B., Mikułowski G., Mróz A., Sekuła K., Jankowski Ł., A decentralized strategy of structural reconfiguration in mitigation of vibrations, Procedia Engineering, ISSN: 1877-7058, DOI: 10.1016/j.proeng.2017.09.363, No.199, pp.1683-1688, 2017
Popławski B., Mikułowski G., Mróz A., Sekuła K., Jankowski Ł., A decentralized strategy of structural reconfiguration in mitigation of vibrations, Procedia Engineering, ISSN: 1877-7058, DOI: 10.1016/j.proeng.2017.09.363, No.199, pp.1683-1688, 2017

Abstract:
This contribution proposes a decentralized closed-loop control algorithm for semi-active mitigation of free vibrations in frame structures. The control uses dedicated dissipative devices, which consist of two controllable structural nodes placed pairwise in both ends of selected structural beams. The nodes are capable of a controlled transition between the standard frame mode of operation (full moment-bearing ability) and the truss mode in which they do not bear any moments and constitute in fact structural hinges. Synchronous switching is equivalent to reconfiguration of the global structure by (dis)allowing the involved beams to transmit moments and to accumulate vibration energy in the form of their bending strain. Upon switching to the truss mode, the accumulated energy is released into high-frequency local vibrations, which undergo quick dissipation by standard mechanisms of material damping. The approach is illustrated in a numerical example and verified in a preliminary experimental test.

Keywords:
Mitigation of vibrations, Semi-active control, Decentralized control, Structural reconfiguration

68.Gawlicki M., Jankowski Ł., Identification of moving loads using the l1 norm minimization, CMM-2017, 22nd International Conference on Computer Methods in Mechanics, 2017-09-13/09-16, Lublin (PL), pp.1-2, 2017
Gawlicki M., Jankowski Ł., Identification of moving loads using the l1 norm minimization, CMM-2017, 22nd International Conference on Computer Methods in Mechanics, 2017-09-13/09-16, Lublin (PL), pp.1-2, 2017

Abstract:
This contribution deals with the inverse problem of indirect identification of moving loads. The identification is performed based on the recorded response of the loaded structure and its numerical model. A specific feature of such problems is a very large number of the degrees of freedom (DOFs) that can be excited and a limited number of available sensors. As a result, unless the solution space is significantly limited, the identification problem is underdetermined: it has an infinite number of exact, observationally indistinguishable solutions. We propose an approach based on the assumption of sparsity of the excitation, which can be expressed in the form of a requirement of a bounded l1 norm of the solution. As long as the loads are sparse, the approach allows them to be freely moving, without the usual assumption of a constant velocity. We test the approach in a numerical example with 10% rms measurement noise and describe an experimental setup that is being prepared to perform experimental verification.

Keywords:
inverse problems, structural mechanics, moving load identification, sparsity, l1 norm

69.Popławski B., Mikułowski G., Mróz A., Jankowski Ł., Decentralized damping of vibrations in 2D frame structures using controllable nodes, SMART 2017, 8th Conference on Smart Structures and Materials, 2017-06-05/06-08, Madrid (ES), pp.94-103, 2017
Popławski B., Mikułowski G., Mróz A., Jankowski Ł., Decentralized damping of vibrations in 2D frame structures using controllable nodes, SMART 2017, 8th Conference on Smart Structures and Materials, 2017-06-05/06-08, Madrid (ES), pp.94-103, 2017

Abstract:
Extensive research efforts have been recently devoted to semi-active structural control with its paradigms of smart self-adaptivity and low consumption of energy, which is used for local adaptation rather than to generate external control forces. Considered application areas include adaptive landing gears, seismic isolation systems, vehicle-track/span systems, power train electro-mechanical systems, damping of flexible space structures, vehicle crashworthiness, arctic engineering, wind turbines, etc. A part of the research concerns semi-active management of strain energy for damping of structural vibrations. Early works considered truss structures with stiffness-switched bars. They later evolved into either standalone one degree of freedom stiffness-switched dampers and isolators or investigations in triggering modal energy transfer to highly-damped high-order modes. The latter researches seem all to study the fundamental vibration mode of a cantilever beam with two detachable layers and differ mainly in the actuator technologies; the main idea is to employ actuators for a quick release of the vibration-related strain energy. This research extends the problem to general 2D frames. Controllable truss-frame nodes are incorporated into the structure. Thanks to their controllable ability to transmit moments, they allow for a quick transition between truss and frame modes. We propose a new, decentralized, closed-loop control strategy based on local energy measures. Vibration damping is more effective than in the previously studied control scheme based on a global energy measure, especially for higher vibration modes. Mitigation of vibrations will be presented in representative numerical examples, including a comparison to the global energy-based control strategy. Finally, results of experimental study, conducted on a structure analogous to the one from numerical simulations, will be demonstrated.

Keywords:
Vibration damping, Smart structures, Semi-active control, PAR strategy, Decentralized damping strategy

70.Zawidzki M., Jankowski Ł., Szklarski J., Structural optimization of a five-unit single-branch Truss-Z modular structure, SMART 2017, 8th Conference on Smart Structures and Materials, 2017-06-05/06-08, Madrid (ES), pp.525-535, 2017
Zawidzki M., Jankowski Ł., Szklarski J., Structural optimization of a five-unit single-branch Truss-Z modular structure, SMART 2017, 8th Conference on Smart Structures and Materials, 2017-06-05/06-08, Madrid (ES), pp.525-535, 2017

Abstract:
Truss-Z (TZ) is an Extremely Modular System (EMS). Such systems allow for creation of structurally sound free-form structures, are comprised of as few types of modules as possible, and are not constrained by a regular tessellation of space. Their objective is to create spatial structures in given environments connecting given terminals without self-intersections and obstacle-intersections. In an EMS, the assembly, reconfiguration and deployment difficulty is moved towards the module, which is relatively complex and whose assembly is not intuitive. As a result, an EMS requires intensive computation for assembling its desired free-form geometrical configuration, while its advantage is the economization of construction and reconfiguration by extreme modularization and mass prefabrication. TZ is a skeletal modular system for creating free-form pedestrian ramps and ramp networks among any number of terminals in space. TZ structures are composed of four variations of a single basic module (Truss-Z module, TZM) subjected to affine transformations (mirror reflection and rotation). The previous research on TZ focused on global discrete optimization of the spatial configuration of modules. This contribution reports on the first attempts at structural optimization of the TZM for a single-branch TZ. Namely, the internal topology of a TZM and sizing of its elements are subject to optimization. An important challenge is due the fact that TZM is to be universal, i.e., it must be designed for the worst case scenario. There are four variations of each module, and due to symmetries there are thus 4^4 = 256 unique 5-unit configurations. The structural performance of all of them needs to be evaluated in terms of a typical structural criterion (the maximum von Mises effective stress), and used for structural optimization at the level of a single TZM.

Keywords:
Extremely Modular System, Truss-Z, Structural optimization, Effective stress

71.Faraj R., Popławski B., Suwała G., Jankowski Ł., Holnicki-Szulc J., Mitigation of dynamic response in frame structures by means of smart joints, SMART 2017, 8th Conference on Smart Structures and Materials, 2017-06-05/06-08, Madrid (ES), pp.138-144, 2017
Faraj R., Popławski B., Suwała G., Jankowski Ł., Holnicki-Szulc J., Mitigation of dynamic response in frame structures by means of smart joints, SMART 2017, 8th Conference on Smart Structures and Materials, 2017-06-05/06-08, Madrid (ES), pp.138-144, 2017

Abstract:
This paper discusses passive and semi-active techniques of structural control by means of smart joints, and then it proposes a specific smart joints system for frame structures and tests its capability in mitigation of free vibrations. Basically, the proposed solution modifies frame beams by addition of truss-type hinges, and its effectiveness relies on the softening effect that occurs in compression due to geometric nonlinearities and which triggers the highly-damped high-frequency response modes of the structure. First, the finite element (FE) model of the specific frame structure with geometrical nonlinearities is derived, and the proposed passive joints are described and incorporated into the model. Then, their principle of operation and effectiveness is examined numerically for the first two natural modes of vibrations with various initial displacement amplitudes. An objective function is proposed to assess joints placement, based on the efficiency in mitigation of the excited vibrations.

Keywords:
Vibration Damping, Structure Response, Smart Structure, Structural Control

72.Zawidzki M., Jankowski Ł., Multicriterial optimization of geometrical and structural properties of the basic module of a single-branch Truss-Z structure, WCSMO12, 12th World Congress of Structural and Multidisciplinary Optimisation, 2017-06-05/06-09, Braunschweig (DE), pp.1-9, 2017
Zawidzki M., Jankowski Ł., Multicriterial optimization of geometrical and structural properties of the basic module of a single-branch Truss-Z structure, WCSMO12, 12th World Congress of Structural and Multidisciplinary Optimisation, 2017-06-05/06-09, Braunschweig (DE), pp.1-9, 2017

Abstract:
Truss-Z (TZ) is an Extremely Modular System (EMS). Such systems allow for creation of structurally sound free-form structures, are comprised of as few types of modules as possible, and are not constrained by a regular tessellation of space. Their objective is to create spatial structures in given environments connecting given terminals without self-intersections and obstacle-intersections. In an EMS, the assembly, reconfiguration and deployment difficulty is moved towards the module, which is relatively complex and whose assembly is not intuitive. As a result, an EMS requires intensive computation for assembling its desired free-form geometrical configuration, while its advantage is the economization of construction and reconfiguration by extreme modularization and mass prefabrication.
TZ is a skeletal modular system for creating free-form pedestrian ramps and ramp networks among any number of terminals in space. TZ structures are composed of four variations of a single basic module (Truss-Z module, TZM) subjected to affine transformations (mirror reflection and rotation). The previous research on TZ focused on global discrete optimization of the spatial configuration of modules. This contribution is the first attempt at structural optimization of the TZM for a single-branch TZ. The result is a multicriterial optimization, where the Pareto front provides the means to strike the optimal balance between geometric and structural assessment criteria.

Keywords:
multicriterial optimization, Truss-Z, effective stress, modular systems

73.Gawlicki M., Jankowski Ł., Identification of moving loads via l1-constrained solutions, ECCOMAS - IPM 2017, 4th International Conference on Inverse Problems in Mechanics of Structures and Materials, 2017-05-31/06-02, Rzeszów - Krasiczyn (PL), pp.25-26, 2017
Gawlicki M., Jankowski Ł., Identification of moving loads via l1-constrained solutions, ECCOMAS - IPM 2017, 4th International Conference on Inverse Problems in Mechanics of Structures and Materials, 2017-05-31/06-02, Rzeszów - Krasiczyn (PL), pp.25-26, 2017

Abstract:
Indirect identification of moving loads based on the measured response is one of the crucial problems in structural health monitoring. It is important in automated assessment of structures and pavements, in traffic monitoring and control, and as a prerequisite for structural control. As such, it has been intensively researched. An important difficulty is that a moving load can excite a very large number of structural Dofs, which all have to be taken into account in the identification procedure based on measurements of a much more limited number of sensors. A straightforward formulation yields thus an underdetermined problem with an infinite number of solutions. Therefore, in most of the approaches so far, the solution space is significantly limited by the assumption that the load corresponds to a single vehicle moving at a constant velocity, which excludes loads of a more general nature (e.g., multiple loads). However, instead of limiting the solution space, it can be noted that in practice moving loads are sparse in time and space, which fits the framework of compressed sensing. Such an a priori knowledge of sparsity is typically expressed by limiting the l1 norm of the solution. To our knowledge, although used in other contexts, the concept has not been applied so far for identification of moving loads. The approach is tested in a numerical example with 10% rms measurement noise. Experimental work is in progress.

74.Hołobut P., Lengiewicz J., Distributed computation of forces in modular-robotic ensembles as part of reconfiguration planning, ICRA 2017, IEEE International Conference on Robotics and Automation, 2017-05-29/06-03, Marina Bay Sands (SG), DOI: 10.1109/ICRA.2017.7989242, No.7989242, pp.2103-2109, 2017
Hołobut P., Lengiewicz J., Distributed computation of forces in modular-robotic ensembles as part of reconfiguration planning, ICRA 2017, IEEE International Conference on Robotics and Automation, 2017-05-29/06-03, Marina Bay Sands (SG), DOI: 10.1109/ICRA.2017.7989242, No.7989242, pp.2103-2109, 2017

Abstract:
We discuss selected mechanical aspects of self-reconfiguration of densely-packed modular robots. The change of connection topology and transport of modules are fundamental mechanisms for these systems, which determine their desired emergent behavior, e.g., movement, shape change or interaction with their surroundings. At the same time, reconfiguration affects the forces between modules. We present a distributed procedure by which a robot can predict if the next planned reconfiguration step will overstress intermodular connections. We use a Finite Element model of a modular robot, with one-node-per-module discretization and beam elements representing intermodular connections. The analysis is restricted to static loads and linear elasticity. We present a distributed procedure of aggregation of the stiffness matrix and iterative solution of the resulting equations of elasticity. The procedure is illustrated with numerical examples and analyzed in terms of its efficiency. © 2017 IEEE.

Keywords:
Finite element method, Modular robots, Stiffness matrix, Distributed computations, Iterative solutions, Reconfiguration planning

75.Meissner M., Metoda zwiększająca dokładność dyskretnej transformaty Hilberta przy wyznaczaniu amplitudy i częstotliwości sygnałów wibroakustycznych, WibroTech 2017, XIX Konferencja Naukowa Wibroakustyki i Wibrotechniki, XIV Ogólnopolskie Seminarium Wibroakustyka w Systemach Technicznych, 2017-05-19/05-20, Pruszków (PL), pp.71-74, 2017
Meissner M., Metoda zwiększająca dokładność dyskretnej transformaty Hilberta przy wyznaczaniu amplitudy i częstotliwości sygnałów wibroakustycznych, WibroTech 2017, XIX Konferencja Naukowa Wibroakustyki i Wibrotechniki, XIV Ogólnopolskie Seminarium Wibroakustyka w Systemach Technicznych, 2017-05-19/05-20, Pruszków (PL), pp.71-74, 2017

Keywords:
wibroakustyka, analiza sygnałów, dyskretna transformata Hilberta

76.Błachowski B., Gutkowski W., Lagrangian dynamics based approach for 3D modelling of human gait, CMM-2017, 22nd International Conference on Computer Methods in Mechanics, 2017-09-13/09-16, Lublin (PL), pp.MS09-33-MS09-34, 2017
Błachowski B., Gutkowski W., Lagrangian dynamics based approach for 3D modelling of human gait, CMM-2017, 22nd International Conference on Computer Methods in Mechanics, 2017-09-13/09-16, Lublin (PL), pp.MS09-33-MS09-34, 2017

Abstract:
The purpose of this study is the mechanism of the spatial movement of a human during walking. The human is considered to be a rigid body with six degrees of freedom, and its mobility is reduced by two constraints. One of the constraints is related to an assumption of constant length of the leg, foot of which is moving along given straight line. The second constraint corresponds to an assumption that human’s centre of mass can move only in vertical plane. The dynamic model of the mechanism is built under above assumptions connected to the human gait kinematics. Then, kinetic energy function is derived. In the next step of the study the muscle force in the stance leg, together with its potential, is discussed. It is assumed that this force is piecewise-linear, which can be reasonably approximated by a cubic polynomial. For that purpose a smoothing procedure is proposed and finally with the aid of the Lagrange function dynamic equations for the 3D human gait are formulated. The last part of the paper is devoted to the numerical solution of obtained nonlinear equations, arising from the Lagrange procedure.

Keywords:
human walking, gait analysis, lagrangian dynamics

77.Jarosik P., Lewandowski M., The feasibility of deep learning algorithms integration on a GPU-based ultrasound research scanner, 2017 IEEE, 2017 IEEE International Ultrasonics Symposium, 2017-09-06/09-09, Washington, DC (US), DOI: 10.1109/ULTSYM.2017.8091750, pp.1-4, 2017
Jarosik P., Lewandowski M., The feasibility of deep learning algorithms integration on a GPU-based ultrasound research scanner, 2017 IEEE, 2017 IEEE International Ultrasonics Symposium, 2017-09-06/09-09, Washington, DC (US), DOI: 10.1109/ULTSYM.2017.8091750, pp.1-4, 2017

Abstract:
Ultrasound medical diagnostics is a real-time modality based on a doctor's interpretation of images. So far, automated Computer-Aided Diagnostic tools were not widely applied to ultrasound imaging. The emerging methods in Artificial Intelligence, namely deep learning, gave rise to new applications in medical imaging modalities. The work's objective was to show the feasibility of implementing deep learning algorithms directly on a research scanner with GPU software beamforming. We have implemented and evaluated two deep neural network architectures as part of the signal processing pipeline on the ultrasound research platform USPlatform (us4us Ltd., Poland). The USPlatform is equipped with a GPU cluster, enabling full software-based channel data processing as well as the integration of open source Deep Learning frameworks. The first neural model (S-4-2) is a classical convolutional network for one-class classification of baby body parts. We propose a simple 6-layer network for this task. The model was trained and evaluated on a dataset consisting of 786 ultrasound images of a fetal training phantom. The second model (Gu-net) is a fully convolutional neural network for brachial plexus localisation. The model uses ‘U-net’-like architecture to compute the overall probability of target detection and the probability mask of possible target locations. The model was trained and evaluated on 5640 ultrasound B-mode frames. Both training and inference were performed on a multi-GPU (Nvidia Titan X) cluster integrated with the platform. As performance metrics we used: accuracy as a percentage of correct answers in classification, dice coefficient for object detection, and mean and std. dev. of a model's response time. The ‘S-4-2’ model achieved 96% classification accuracy and a response time of 3 ms (334 predictions/s). This simple model makes accurate predictions in a short time. The ‘Gu-net’ model achieved a 0.64 dice coefficient for object detection and a 76% target's presence classification accuracy with a response time of 15 ms (65 predictions/s). The brachial plexus detection task is more challenging and requires more effort to find the right solution. The results show that deep learning methods can be successfully applied to ultrasound image analysis and integrated on a single advanced research platform

Keywords:
Ultrasonic imaging, Neural networks, Convolution, Machine learning, Image segmentation, Kernel

78.Rozbicki J., Witek B., Steifer T., Lewandowski M., Doppler-based blood pressure measurement system for patients supported by a continuous-flow rotary left ventricular assist device, 2017 IEEE, 2017 IEEE International Ultrasonics Symposium, 2017-09-06/09-09, Washington, DC (US), DOI: 10.1109/ULTSYM.2017.8091990, pp.1-4, 2017
Rozbicki J., Witek B., Steifer T., Lewandowski M., Doppler-based blood pressure measurement system for patients supported by a continuous-flow rotary left ventricular assist device, 2017 IEEE, 2017 IEEE International Ultrasonics Symposium, 2017-09-06/09-09, Washington, DC (US), DOI: 10.1109/ULTSYM.2017.8091990, pp.1-4, 2017

Abstract:
The medical management of patients with continuous-flow left ventricular assist devices (LVADs) requires frequent measurement and analysis of various physiological parameters. Among the most important is blood pressure (BP), which cannot be reliably measured by the standard oscillometric method because of an impaired pulsation due to continuous flow. The objective of this work is to show the feasibility of ultrasound-based BP measurement in a portable, easy to use device for patients with LVAD in home-based rehabilitation environments, enabling long-term remote monitoring. We have implemented a BP measurement system which uses continuous wave (CW) Doppler ultrasound for blood flow detection. The system is based on a standard cuff design with custom analog CW circuitry connected to a high-performance, low-power 32-bit microcontroller (ARM Cortex-M7). The uC is responsible for system control, as well as Doppler signal acquisition and processing. A dedicated ultrasound probe equipped with an elastic strap is placed over the radial artery. In the target solution, the cuff pressure and CW signal will be analyzed in real-time to provide systolic and/or mean blood pressure. At present, we have acquired raw signals for off-line analysis. The system was tested in clinical experiments both on healthy patients and patients with three types of commercially available LVADs (HeartWare, HeartMate II and HeartMate III). The observed morphology of Doppler signals in patients with LVADs was much more variable between patients and pumps. In most cases, we were able to estimate the systolic pressure, but the measurement of diastolic pressure was not conclusive. We observed variable blood flow patterns generated by the Lavare cycle (a periodic speed modulation feature of some LVADs), which further complicates the estimation. A prototype of an automatic BP measuring device for patients with rotary LVADs has been demonstrated. In the next step, we are planning an animal validation study with invasive blood pressure monitoring

Keywords:
Biomedical monitoring, Doppler effect, Blood pressure, Blood, Pressure measurement, Ultrasonic variables measurement, Standards

79.Ziółkowski A., Disastrous air crash and two investigations with different results, International Journal of Forensic Engineering, ISSN: 1744-9944, DOI: 10.1504/IJFE.2017.10005136, Vol.3, No.4, pp.277-302, 2017
Ziółkowski A., Disastrous air crash and two investigations with different results, International Journal of Forensic Engineering, ISSN: 1744-9944, DOI: 10.1504/IJFE.2017.10005136, Vol.3, No.4, pp.277-302, 2017

Abstract:
The case study is analyzed of the catastrophe of Polish Air Force One, TU-154M aircraft on 10th of April 2010, near Smolensk North airfield, Russia. The catastrophe ended up in total destruction of the aircraft and death of all the passengers and crew on board. The results of the official investigations of the Russian Federation executed by the Interstate Aviation Committee and Poland executed by the Committee for Investigation of State Aviation Accidents are recalled, which found that the crash resulted due to pilot's errors. The evidence is presented showing faults in official examination proceedings and thus existence of grounds for possibility of drawing false conclusions. An academic investigation effort is undertaken to reconstruct the course of events during the last few seconds of flight of the TU-154M aircraft. The publicly available data, photographic evidence, and circumstantial information have been analyzed, which allowed pointing out a number of observations, which were not reliably explained by official reports scenarios. In view of that, execution of a new fully fledged repair investigation is recommended.

Keywords:
Air Force One, Polish TU-154M, Smolensk, aircraft crash, catastrophe, academic investigation, repair examination, abductive analysis, metallic fragments, airframe wreckage, blast, explosive damage, TAWS, aircraft safety engineering

80.Byra M., Piotrzkowska-Wróblewska H., Dobruch-Sobczak K., Nowicki A., Combining Nakagami imaging and convolutional neural network for breast lesion classification, 2017 IEEE, 2017 IEEE International Ultrasonics Symposium, 2017-09-06/09-09, Washington, DC (US), DOI: 10.1109/ULTSYM.2017.8092154, pp.1-4, 2017
Byra M., Piotrzkowska-Wróblewska H., Dobruch-Sobczak K., Nowicki A., Combining Nakagami imaging and convolutional neural network for breast lesion classification, 2017 IEEE, 2017 IEEE International Ultrasonics Symposium, 2017-09-06/09-09, Washington, DC (US), DOI: 10.1109/ULTSYM.2017.8092154, pp.1-4, 2017

Abstract:
In this paper we propose a computer-aided diagnosis system for the breast lesion classification. Our approach is based on quantitative ultrasound and deep learning. We used the Nakagami imaging to create parametric maps of breast lesions that illustrate tissue scattering properties. For this task the sliding window technique was applied. The Nakagami parameter was calculated using the maximum likelihood estimator. Next, we used the Nakagami parameter maps to train a convolutional neural network. Classification performance was evaluated by 5-fold cross-validation. We obtained the area under the receiver operating characteristic curve equal to 0.91. The results showed that our approach is useful to distinguishing between malignant and benign breast lesions. The proposed method serves as a general approach for tissue characterization and differentiation. The Nakagami parameter used in this study can be replaced with other QUS parameters and the neural network can be trained in a similar fashion.

Keywords:
Nakagami imaging, quantitative ultrasound, convolutional neural networks, breast lesion classification, deep learning

81.Byra M., Wójcik J., Nowicki A., Ultrasound nonlinearity parameter assessment using plane wave imaging, 2017 IEEE, 2017 IEEE International Ultrasonics Symposium, 2017-09-06/09-09, Washington, DC (US), DOI: 10.1109/ULTSYM.2017.8092733, pp.1-4, 2017
Byra M., Wójcik J., Nowicki A., Ultrasound nonlinearity parameter assessment using plane wave imaging, 2017 IEEE, 2017 IEEE International Ultrasonics Symposium, 2017-09-06/09-09, Washington, DC (US), DOI: 10.1109/ULTSYM.2017.8092733, pp.1-4, 2017

Abstract:
In this paper we investigate how to assess the ultrasound nonlinearity coefficient using plane wave imaging. We employ the technique based on excitation of the medium with ultrasonic pulses of increasing amplitude level. As the pulse pressure is increased, due to medium nonlinearity, higher fraction of energy is transferred from the fundamental to higher harmonics during the propagation. In this case the amplitude of the backscattered echo is not linear in respect to the initial pulse amplitude at source. This phenomenon can be used for the nonlinearity coefficient assessment and show its implementation for the plane wave imaging. The method was validated experimentally using a wire phantom immersed in water and scanned using the Verasonics scanner. We discuss the usefulness of the proposed technique and its shortcomings. In comparison to other nonlinearity coefficient assessment methods, the presented technique works in the pulse-echo mode and it doesn't require information on second harmonic or using a special wide-band transducer. The method can be implemented directly into a medical scanner.

Keywords:
Plane wave imaging, nonlinear ultrasound, quantitative ultrasound, coefficient of nonlinearity

82.Pawłowski P., Frąś T., Numerical and experimental investigation of asymmetrical contact between a steel plate and armour-piercing projectiles, LS-DYNA 2017, European LS-DYNA Conference 2017, 2017-05-09/05-11, Salzburg (AT), pp.1-9, 2017
Pawłowski P., Frąś T., Numerical and experimental investigation of asymmetrical contact between a steel plate and armour-piercing projectiles, LS-DYNA 2017, European LS-DYNA Conference 2017, 2017-05-09/05-11, Salzburg (AT), pp.1-9, 2017

Abstract:
Protection of combat-vehicles against impacts of small-calibre projectiles may be improved by the application of relatively thin and hard steel plates perforated by a plurality of holes. It is observed that due to the contact with a plate,the core of armour-piercing (AP) projectiles may be shattered, partially eroded or rotated, depending on the hit-position. The contact asymmetry is the strongest when a projectile hits a hole edge, its core undergoes bending and tends to fracture. The presented study discusses two methods of modelling of the contact and interactions between a bullet and a steel target. One of them is the explicit Lagrangian simulation of impacts of a fully represented AP projectile, another one is the semi-analytical model based on the integration of the motion equations of a 6 DOF rigid projectile. The results of numerical and semi-analytical approaches are compared with the ballistic impact experiment, in which the defeat mechanisms provided by 4-mm-thick slotted bainitic plates (Pavise™ SBS 600P) against hard-core 7.62 mm P80 0.30 AP x 51 (.308 Win) projectiles were verified, [1].

83.Chikahiro Y., Ario I., Pawlowski P., Graczykowski C., Nakazawa M., Holnicki-Szulc J., Ono S., Dynamics of the scissors-type Mobile Bridge, EURODYN 2017, X International Conference on Structural Dynamics, 2017-09-10/09-13, Rome (IT), DOI: 10.1016/j.proeng.2017.09.339, No.199, pp.2919-2924, 2017
Chikahiro Y., Ario I., Pawlowski P., Graczykowski C., Nakazawa M., Holnicki-Szulc J., Ono S., Dynamics of the scissors-type Mobile Bridge, EURODYN 2017, X International Conference on Structural Dynamics, 2017-09-10/09-13, Rome (IT), DOI: 10.1016/j.proeng.2017.09.339, No.199, pp.2919-2924, 2017

Abstract:
We have experienced many times a phenomenon in which a bridge is washed away due to a typhoon, heavy rain in the rainy season, localized torrential rain, tsunami, and other flood disasters, or in which a bridge is damaged by an earthquake or a tremor. There is accordingly increasing demand for new technology and science to restore bridges that have been washed away or damaged. The paper presents a new type of emergency bridge, called Mobile Bridge™(MB), which can be quickly constructed in case of damages after a natural disaster. The concept of the bridge is based on the application of scissor-type mechanism, which provides its rapid deployment. Up to now several experimental MBs of different size were constructed and tested. The presented research reviews fundamental numerical and experimental results for the MB version 4.0 (MB4.0). Experimental testing included strain and acceleration measurements in free and forced loading conditions. From these results, it was possible to estimate basic dynamic characteristics of the bridge. Besides, in order to provide a basis for development of new construction methods for structural reinforcement and suppression of vibrations, various numerical analyses were conducted. The conducted research allows for a better and safer design of the movable and foldable full-scale bridge, the MB.

Keywords:
deployable bridge, scissors-type bridge, emergency bridge, light-weight structure, temporary bridge

84.Graczykowski C., Pawłowski P., Mathematical Modelling of Adaptive Skeletal Structures for Impact Absorption and Vibration Damping, EURODYN 2017, X International Conference on Structural Dynamics, 2017-09-10/09-13, Rome (IT), DOI: 10.1016/j.proeng.2017.09.093, No.199, pp.1671-1676, 2017
Graczykowski C., Pawłowski P., Mathematical Modelling of Adaptive Skeletal Structures for Impact Absorption and Vibration Damping, EURODYN 2017, X International Conference on Structural Dynamics, 2017-09-10/09-13, Rome (IT), DOI: 10.1016/j.proeng.2017.09.093, No.199, pp.1671-1676, 2017

Abstract:
The paper describes mathematical modelling of adaptive skeletal structures, which are equipped with semi-active dissipaters based on smart fluids or fast-operating valves and utilize the paradigm of real-time adaptation to external loading. The proposed approach is based on three subsequent stages: i) exact thermodynamic modelling of a single semi-active dissipater with the use of mass, momentum and energy conservation laws, ii) global description of the entire skeletal structure considered as an assembly of semi-active dissipaters in certain geometrical configuration, iii) real-time control of the fluid flow inside semi-active dissipaters providing instantaneous adaptability to actual dynamic loading. This methodology enables accurate representation of mechanical characteristics of the skeletal structure and reliable analysis of its adaptation capabilities.

Keywords:
adaptive structures, skeletal structures, impact absorption, vibration damping

85.Nakielski P., Pierini F., Piechocka I.K., Kowalewski T.K., Blood clotting in the contact with polymer nanofibers, Bloodsurf2017, Blood-biomaterial interface: where medicine and biology meet physical sciences and engineering, 2017-09-17/09-21, Clemson, SC (US), pp.35, 2017
Nakielski P., Pierini F., Piechocka I.K., Kowalewski T.K., Blood clotting in the contact with polymer nanofibers, Bloodsurf2017, Blood-biomaterial interface: where medicine and biology meet physical sciences and engineering, 2017-09-17/09-21, Clemson, SC (US), pp.35, 2017

Abstract:
Electrospun nanofibers are increasingly studied thanks to their potential applications in biomedical devices that include drug delivery systems and tissue engineering scaffolds [1]. Numerous synthetic and natural polymers were used to develop nanofibrous materials. Nanostructured materials high porosity, surface-to- volume ratio together with the ease in surface functionalization and drug incorporation, make them perfect candidates for the development of hemostats. Immediate hemorrhage management becomes crucial to preventing death and serious injury in emergency situations. Severe injuries caused by e.g. traffic accidents are the third leading cause of death worldwide [2]. Research on medical incidents of soldiers stationed in Iraq in 2003-2004 showed that the main cause of death was massive hemorrhage that led to death in about 51% of the rescued soldiers [3]. There is no universal dressing and despite the development of new hemostats, they fail in many preclinical studies. Therefore, there is a need to define most important nanofibrous material characteristics that are responsible for rapid and effective bleeding arrest.
There is little research on nanostructured hemostats, regarding the impact of nanofibrous surface on blood and its components. Nonetheless, because of the wide use of nanofibres in wound dressings, artificial blood vessels as well as heart valves, there is knowledge helpful in determining material surface chemistry, wettability and other, which can affect blood coagulation. The very first findings appeared in the research where it was found that even polymers having excellent antiplatelet adhesion abilities, triggered increased platelet adhesion and activation when they were in the form of nanofibers. In several other studies, scaffold morphology, was found to have larger impact on platelet adhesion and activation than differences in the chemistry of the polymers used [4]. More specifically, it was found that materials with fiber diameter higher than 1 µm triggered higher platelet adhesion and aggregation than smaller fibers. In other research, nanofiber stiffness was assessed as more dominating than biological moieties and surface roughness of the nanofiber [5]. In spite of all, analyzed literature presents many contradictory results or findings that had low or no impact on blood clotting in research results of other groups. Hence, additional research and novel experimental methods are needed to find nano features that impact hemostat efficiency.
Acknowledgements
The authors acknowledge the support from NCN grant no. 2015/19/D/ST8/03192.
References:
[1] Nakielski P. et al., J Biomed Mater Res Part B 103B:282–291, 2015
[2] Kauvar D. et al., J of Trauma-Injury Inf &Crit Care, 60(6):3-11, 2006
[3] Kelly J.F. et al., J Trauma, 64:S21-6; 2008
[4] Milleret V. et al., Acta Biomaterialia 8(12):4349–4356, 2012
[5] Merkle V.M. et al., Appl. Mater. Interfaces, 7 (15):8302–8312, 2015

Keywords:
blood-biomaterial interactions, nanofibers, clotting,

86.Chmielewski M., Pietrzak K., Strojny-Nędza A., Kaszyca K., Nosewicz S., Jarząbek D., The effect of nickel coating on the properties of Cu-SiC composites, EUROMAT 2017, European Congress and Exhibition on Advanced Materials and Processes, 2017-09-17/09-22, Thessaloniki (GR), pp.1, 2017
87.Nosewicz S., Rojek J., Maździarz M., Kowalczyk P., Wawrzyk K., Chmielewski M., Pietrzak K., Multiscale modeling of pressure-assisted sintering process, EUROMAT 2017, European Congress and Exhibition on Advanced Materials and Processes, 2017-09-17/09-22, Thessaloniki (GR), pp.1, 2017
88.Chikahiro Y., Ario I., Adachi K., Shimizu S., Zenzai S., Pawłowski P., Graczykowski C., Holnicki-Szulc J., FUNDAMENTAL STUDY ON DYNAMIC PROPERTY OF SCISSORING BRIDGE FOR DISASTER RELIEF, ENOC 2017, 9th European Nonlinear Dynamics Conference, 2017-06-25/06-30, Budapest (HU), pp.1-2, 2017
Chikahiro Y., Ario I., Adachi K., Shimizu S., Zenzai S., Pawłowski P., Graczykowski C., Holnicki-Szulc J., FUNDAMENTAL STUDY ON DYNAMIC PROPERTY OF SCISSORING BRIDGE FOR DISASTER RELIEF, ENOC 2017, 9th European Nonlinear Dynamics Conference, 2017-06-25/06-30, Budapest (HU), pp.1-2, 2017

Abstract:
The world has seen many kinds of natural disasters, which have critically influenced the residents’ lives by causing damage to infrastructure. To realize rapid rescue efforts in an emergency situation,we propose a deployable emergency bridge, called Mobile Bridge TM [1], based on the theory of foldable structures[2]and the concept of Multi-Folding Microstructures (MFM)[3]. The current research presents the fundamental,numerical and experimental results obtained for the pedestrian and vehicle Mobile Bridges. In this paper, it is considered the localized linearization problem with the fixed an angle although this bridge contains a geometrical nonlinearity of scissors structure.Additionally, a seismic response analysis is conducted for the case where the Mobile Bridge is used in the disaster area as an emergency bridge. This allows for a better and safer structural design of the Mobile Bridge, which is patented in [4],[5].

89.Faraj R., Graczykowski C., Holnicki-Szulc J., Knap L., Seńko J., Adaptable pneumatic shock-absorber, SMART 2017, 8th Conference on Smart Structures and Materials, 2017-06-05/06-08, Madrid (ES), pp.1, 2017
90.Faraj R., Graczykowski C., Holnicki-Szulc J., Investigations on adaptable and adaptive impact absorption, ICAST2017, The 28th International Conference on Adaptive Structures and Technologies, 2017-10-08/10-11, Kraków (PL), pp.1, 2017
91.Szymczak T., Kowalewski Z.L., ON THE CRUCIFORM SPECIMENS FOR MATERIALS TESTING, DAS 2017, 34th Danubia-Adria Symposium on Advances in Experimental Mechanics, 2017-09-19/09-22, Trieste (IT), pp.1-2, 2017
92.Libura T., Kowalewski Z.L., Kowalczyk-Gajewska K., THE BAUSCHINGER EFFECT IN THIN SHEET MAGNESIUM ALLOY USING ANTI-BUCKLING FIXTURE, DAS 2017, 34th Danubia-Adria Symposium on Advances in Experimental Mechanics, 2017-09-19/09-22, Trieste (IT), pp.1-2, 2017
93.Kukla D., Zagórski A., Miś R., Wyszkowski M., BADANIA DIAGNOSTYCZNE RUR WYMIENNIKÓW CIEPŁA Z ZASTOSOWANIEM TECHNIK NIENISZCZĄCYCH, XXIII Seminarium NIENISZCZĄCE BADANIA MATERIAŁÓW, 2017-03-15/03-17, Zakopane (PL), pp.1-18, 2017
94.Pęcherski R.B., Nowak Z., Nowak M., Natonik K.J., Potoczek M., Śliwa R.E., PROBLEMS OF VIRTUAL CELLULAR MATERIALS: REPRESENTATIVE VOLUME ELEMENT AND ENERGY-BASED ASSESSMENT OF FAILURE STRENGTH , DBM, 11th Workshop Dynamic Behaviour of Materials and its Applications in Industrial Processes, 2017-08-23/08-25, Guimarães (PT), pp.12-13, 2017
Pęcherski R.B., Nowak Z., Nowak M., Natonik K.J., Potoczek M., Śliwa R.E., PROBLEMS OF VIRTUAL CELLULAR MATERIALS: REPRESENTATIVE VOLUME ELEMENT AND ENERGY-BASED ASSESSMENT OF FAILURE STRENGTH , DBM, 11th Workshop Dynamic Behaviour of Materials and its Applications in Industrial Processes, 2017-08-23/08-25, Guimarães (PT), pp.12-13, 2017

Abstract:
Three kinds of cellular materials are considered. Depending on geometry and physical properties of the skeleton, these are metallic cellular materials with convex or reentrant open cell structure. To the third group belong alumina foams produced by gel casting method.
Finite element computations are used to analyse mechanical properties of a material volume. Such an analysis is usually related with big computational costs. Therefore, it is important to keep the size of the considered cellular material volume as small as possible. On the other hand, the validity of the continuum model requires the proper size of the RVE. The aim of the study is to estimate the sufficient size of representative volume element (RVE) in order to assess the validity of the elastic model of the considered cellular material. An array of cubes of virtual cellular material is used to compute the particular deformation modes providing elastic moduli, Young modulus E, shear modulus G and bulk modulus K as well as the resulting Poisson’s ratio.
Also the results of the microtomography of alumina foams are used to create the „virtual cellular material” i.e. the numerical model reconstructing the structure of real foam skeleton. The numerical simulations of compression test are performed. The results are compared with experimental data of elastic moduli and failure strength. The numerical simulations of failure strength under compression for alumina foams are performed. The calculations with use of the numerical model are time consuming. Therefore, the simplified method of the assessment of failure strength is proposed. It is based on the energy-based hypothesis on the equivalence of of elastic moduli and the resulting equivalence of the values of failure strength of real alumina foam and the cellular material with regular structure (e.g. fcc type). The justification of the hypothesis based on experimental data of compression of alumina foam are discussed and the range of validity as regards porosity values is studied.

Keywords:
virtual cellular materials, convex skeleton, reentrant skeleton. representative volume element, numerical simulations

95.Pęcherski R.B., Nowak Z., APPLICATION OF VIRTUAL CELLULAR MATERIAL CONCEPT FOR THE SIMULATIONS OF DYNAMIC LOADING PROCESSES , MatCel’2017 & DynMatCel’2017, Cellular Materials: Structural Behaviour, Modelling and Characterisation, 2017-09-25/09-27, Aveiro (PT), pp.54, 2017
Pęcherski R.B., Nowak Z., APPLICATION OF VIRTUAL CELLULAR MATERIAL CONCEPT FOR THE SIMULATIONS OF DYNAMIC LOADING PROCESSES , MatCel’2017 & DynMatCel’2017, Cellular Materials: Structural Behaviour, Modelling and Characterisation, 2017-09-25/09-27, Aveiro (PT), pp.54, 2017

Abstract:
The subject of the study is the models based on digital microstructure, in particular open-cell metallic materials with the skeleton of convex or re-entrant cells. Recently, the auxetic materials have attracted increasing attention in the context of modern materials applications. The dynamic properties of such materials are less known. Impact compressions of the two kind of cellular materials under high-velocity are numerically analysed, [1]. To simulate the deformation processes the finite element program ABAQUS is used. The computer tomography makes the basis for the formulation of computational model and finite element discretization of the skeleton of virtual cellular material. For numerical simulations the constitutive elasto-viscoplasticity equations are applied that describe the dynamic behaviour of OFHC Cu. The numerical predictions of compression kinematics of the skeleton and crushing force for velocity 50 and 300 m/s are discussed. The results of computations are completed with the analysis of shock wave propagation.

Keywords:
virtual cellular material, dynamic loading, crushing force, auxetic material, OFHC Cu, shock vaves

96.Nowak Z., Nowak M., Pęcherski R.B., DYNAMIC COMPRESSION STRENGTH OF COPPER OPEN-CELL FOAMS , DBM, 11th Workshop Dynamic Behaviour of Materials and its Applications in Industrial Processes, 2017-08-23/08-25, Guimarães (PT), pp.8-9, 2017
Nowak Z., Nowak M., Pęcherski R.B., DYNAMIC COMPRESSION STRENGTH OF COPPER OPEN-CELL FOAMS , DBM, 11th Workshop Dynamic Behaviour of Materials and its Applications in Industrial Processes, 2017-08-23/08-25, Guimarães (PT), pp.8-9, 2017

Abstract:
Metal foams in view of their structural strength and mechanical energy absorption capability under high speed impact can be utilized as energy absorbers. It is important to understand the propagation of compaction waves in the foams. Most commercially available metal foams are made of aluminium, nickel, copper, and metal alloys. Two kinds of foams exist, namely the open-cell and the closed-cell foams. Typically, the pore density of uncompressed open-cell foams varies between 5 to 100 PPI (pores per inch), while the porosity is in the range from 70% to 95%. Literature provides several examples of metal foams solutions for energy absorption applications, dealing with both experimental, numerical and analytical studies.
The subject of the study are the models based on digital micro-structures, in particular open cell metallic foams characterized with the skeleton formed of convex or re-entrant cells. The re-entrant materials revealing negative Poisson’s ratio have attracted increasing attention in the context of modern materials applications, [3]. The goal of the presented investigations is to study the impact limits and absorption energy of these two kind of open cell metallic foams. To simulate the deformation processes the finite element program ABAQUS is used. The computer tomography made the basis for the formulation of computational model of the foam and the finite element discretization of the skeleton.
From each reconstructed volume, a representative cubic volume element was extracted. For numerical simulations the constitutive elasto-viscoplasticity model is applied that defines the dynamic behaviour of oxygen-free high conductivity (OFHC) Cu using the experimental data reported in the literature. The chosen material model for the numerical simulation is the Cowper-Symonds model. The model is able to predict the mechanical behaviour of the materials under different loading conditions and it is implemented in many FEM codes in order to investigate and describe problems such as ballistic impacts or problems in which the strain-rates component are relevant. In numerical simulations the bottom displacements in the impact direction are fixed and initial velocity V0 on the top surface and general contact (steel wall-Cu foam and selfcontact Cu foam) with the friction coefficient 0.35 is assumed. The numerical predictions of axial force (crushing force) within the wide range of velocity: from 50 to 300 m/s are discussed. The shock state variables derived from Hugoniot relation and the conservation laws are used for comparison with FEM simulations.

Keywords:
copper open-cell foams, compaction waves, shock waves, crushing force, elasto-viscoplasticity model

97.Frąś L.J., Pęcherski R.B., DYNAMIC BEHAVIOUR OF MAGNETHOREOLOGICAL MATERIALS , MatCel’2017 & DynMatCel’2017, Cellular Materials: Structural Behaviour, Modelling and Characterisation, 2017-09-25/09-27, Aveiro (PT), pp.17-18, 2017
Frąś L.J., Pęcherski R.B., DYNAMIC BEHAVIOUR OF MAGNETHOREOLOGICAL MATERIALS , MatCel’2017 & DynMatCel’2017, Cellular Materials: Structural Behaviour, Modelling and Characterisation, 2017-09-25/09-27, Aveiro (PT), pp.17-18, 2017

Abstract:
The magnethoreological material is based on the ferroparticles immersed in carrying fluid. The acting magnetic field is forcing ferroelements to connect into characteristic structure - braids. Behaviour of the magnethoreological material at the high strain rates will be described by Perzyna model. The created model will be verified with use of dedicated laboratory set up.

Keywords:
magnethoreological material, viscoplasticity model, dynamic behaviour, ferroelements.

98.Chrzanowska J., Hoffman J., Mościcki T., Denis P., Szymański Z., Comparison of tungsten boride layers deposite by laser pulse, magnetron sputtering and combined magnetron sputtering-pulsed laser deposition, COLA 2017, International Conference on Laser Ablation, 2017-09-03/09-08, Marseille (FR), pp.202-202, 2017
99.Zawidzki M., Szklarski J., Single-branch Truss-Z Optimization Based on Image Processing and Evolution Strategy, PARENG2017, International Conference on Parallel, Distributed, Grid and Cloud Computing for Engineering, 2017-05-30/05-31, Pécs (HU), DOI: doi:10.4203/ccp.111.28, pp.28, 2017
Zawidzki M., Szklarski J., Single-branch Truss-Z Optimization Based on Image Processing and Evolution Strategy, PARENG2017, International Conference on Parallel, Distributed, Grid and Cloud Computing for Engineering, 2017-05-30/05-31, Pécs (HU), DOI: doi:10.4203/ccp.111.28, pp.28, 2017

Abstract:
Truss-Z (TZ) is a skeletal system for creating free-form pedestrian ramps and ramp networks among any number of terminals in space. TZ structures are composed of four variations of a single basic unit subjected to affine transformations (mirror reflection, rotation and combination of both). This paper presents a new approach to the optimization of the layout of a singlebranch Truss-Z (STZ) in constrained environment (E). The problem is formulated as follows: create an STZ from a start (sP) to end point (eP) without self-intersections and collisions with two obstacles. This is a multi-criterial optimization problem where three independent objectives are subjected to minimization: the total number of modules (n), the “reaching error” to eP and the “overlapping error”. All three criteria are weighted and aggregated to a single cost function (CF). The calculation of CF is based on image processing of rendered geometry of individual STZs in E. The optimization is performed by population-based classic heuristic method - Evolution Strategy (ES). The computation of CF is the most time consuming, however, its parallelization is rather straightforward. Two parallelization methods are presented: distribution over Wolfram Lightweight Grid and application of general purpose graphical processing units (GPGPUs) with the use of CUDA platform.

Keywords:
Extremely Modular System, Truss-Z, discrete optimization, image processing, rasterization, GPU, CUDA, Mathematica, Wolfram Lightweight Grid.

100.Zawidzki M., Szklarski J., Preliminary Optimization of Pipe-Z Reconfiguration, PARENG2017, International Conference on Parallel, Distributed, Grid and Cloud Computing for Engineering, 2017-05-30/05-31, Pécs (HU), DOI: doi:10.4203/ccp.111.27, pp.27, 2017
Zawidzki M., Szklarski J., Preliminary Optimization of Pipe-Z Reconfiguration, PARENG2017, International Conference on Parallel, Distributed, Grid and Cloud Computing for Engineering, 2017-05-30/05-31, Pécs (HU), DOI: doi:10.4203/ccp.111.27, pp.27, 2017

Abstract:
Pipe-Z (PZ) is a parametric design system which comprised of a congruent modules (PZM) allows the creation of complex three-dimensional, single-branch structures which can be represented by mathematical knots. Once the geometrical parameters are set for the PZM, the shape of PZ is controlled solely by relative twists of the PZMs in a sequence. Therefore each PZM has one degree of freedom (1DOF). This paper presents the preliminary optimization of PZ reconfiguration from a “straight tube” to a half-torus. Here the displacement of PZMs transverse to the “bending direction” is to be minimized. In other words, it resembles “truing” of a wheel. In the considered case, the PZ is comprised of eight hexagonal PZMs. Thus every PZM can have six possible positions relative to the previous module. The initial (PZI) and target (PZT) configurations are given. Since the time-steps and relative twists are discrete, it is a discrete optimization and has combinatorial nature. The number of possible configurations grows astronomically with the assumed number of time-steps from one position to another and the number of PZMs. However, the optimization algorithm can be naturally parallelized. At first the concept of PZ is outlined, followed by the experiment. The results are illustrated and discussed.

Keywords:
Extremely Modular System, Pipe-Z, Arm-Z, discrete optimization, dihedral rotation, “snakebot”, reconfiguration.

101.Secomski W., Wójcik J., Klimonda Z., Nowicki A., Estimation and Measurement of the Streaming Velocity in Presence of the Contrast Agents or Blood Mimicking Scatterers, 2017 IEEE, 2017 IEEE International Ultrasonics Symposium, 2017-09-06/09-09, Washington, DC (US), DOI: 10.1109/ULTSYM.2017.8092858, pp.1-4, 2017
Secomski W., Wójcik J., Klimonda Z., Nowicki A., Estimation and Measurement of the Streaming Velocity in Presence of the Contrast Agents or Blood Mimicking Scatterers, 2017 IEEE, 2017 IEEE International Ultrasonics Symposium, 2017-09-06/09-09, Washington, DC (US), DOI: 10.1109/ULTSYM.2017.8092858, pp.1-4, 2017

Abstract:
Streaming velocity mainly depends on the intensity and absorption of ultrasound in the media. For high frequencies exceeding 20 MHz the speed of streaming in blood is also affected by scattering effects on the blood cells and contrast agent microbubbles. According to theoretical calculations, 12.2 % increase in streaming velocity for 1 g/l starch concentration rise should be expected. The theory has also shown the reduction of the streaming velocity by low-density scatterers, estimated decrease was -9.7 % for BR14 contrast agent. The experimental measurements of streaming velocities were done in blood mimicking fluid and Bracco BR14 microbubbles dissolved in water. The streaming was generated by a plane 20 MHz ultrasonic transducer driven by a pulsed Doppler flowmeter. For starch concentration changing from 0.01g/l (reference fluid) up to 1g/l the streaming velocity increased by 13%, very close to the theoretical prediction. For BR14, the measured velocity was 9% less than in reference fluid and remained independent on the microbubbles concentration.

Keywords:
streaming; radiation force; starch; contrast agent; blood

102.Żołek N., Wójcik J., Optimized Acoustic Echoes Simulator in Fourier domain, 2017 IEEE, 2017 IEEE International Ultrasonics Symposium, 2017-09-06/09-09, Washington, DC (US), DOI: 10.1109/ULTSYM.2017.8092654, pp.1-3, 2017
Żołek N., Wójcik J., Optimized Acoustic Echoes Simulator in Fourier domain, 2017 IEEE, 2017 IEEE International Ultrasonics Symposium, 2017-09-06/09-09, Washington, DC (US), DOI: 10.1109/ULTSYM.2017.8092654, pp.1-3, 2017

Abstract:
A new toolbox for the simulation of acoustic wave fields is described. The toolbox, USim, is designed to make an acoustic modeling of ultrasound propagation in tissues reliable and fast. The forward simulations of the wave field are based on the Born-Neumann single scattering approximation of the solution of Sturm-Liouville equation. The toolbox allows simulating the ultrasound wave propagation in non-homogeneous media containing finite size scatterers similar to those existing in a real tissues. The approach of calculations conducted in Fourier space increases the efficiency and allows taking into account the absorption and density phenomena in a simple and correct way.

Keywords:
acoustic propagation; numerical simulations; fourier domain

103.Secomski W., POMIARY POLA AKUSTYCZNEGO, XXIII Seminarium NIENISZCZĄCE BADANIA MATERIAŁÓW, 2017-03-15/03-17, Zakopane (PL), pp.139-146, 2017
104.Piechocka I.K., Jansen K.A., Broedersz C.P., Kurniawan N.A., MacKintosh F.C., Koenderink G.H., Multi-scale strain-stiffening of semiflexible bundle networks, SOFT MATTER, ISSN: 1744-683X, DOI: 10.1039/c5sm01992c, Vol.12, No.7, pp.2145-2156, 2016
Piechocka I.K., Jansen K.A., Broedersz C.P., Kurniawan N.A., MacKintosh F.C., Koenderink G.H., Multi-scale strain-stiffening of semiflexible bundle networks, SOFT MATTER, ISSN: 1744-683X, DOI: 10.1039/c5sm01992c, Vol.12, No.7, pp.2145-2156, 2016

Abstract:
Bundles of polymer filaments are responsible for the rich and unique mechanical behaviors of many biomaterials, including cells and extracellular matrices. In fibrin biopolymers, whose nonlinear elastic properties are crucial for normal blood clotting, protofibrils self-assemble and bundle to form networks of semiflexible fibers. Here we show that the extraordinary strain-stiffening response of fibrin networks is a direct reflection of the hierarchical architecture of the fibrin fibers. We measure the rheology of networks of unbundled protofibrils and find excellent agreement with an affine model of extensible wormlike polymers. By direct comparison with these data, we show that physiological fibrin networks composed of thick fibers can be modeled as networks of tight protofibril bundles. We demonstrate that the tightness of coupling between protofibrils in the fibers can be tuned by the degree of enzymatic intermolecular crosslinking by the coagulation factor XIII. Furthermore, at high stress, the protofibrils contribute independently to the network elasticity, which may reflect a decoupling of the tight bundle structure. The hierarchical architecture of fibrin fibers can thus account for the nonlinearity and enormous elastic resilience characteristic of blood clots.

105.Ortwein R., Ryś M., Skoczeń B., Damage evolution in a stainless steel bar undergoing phase transformation under torsion at cryogenic temperatures, INTERNATIONAL JOURNAL OF DAMAGE MECHANICS, ISSN: 1056-7895, DOI: 10.1177/1056789516656746, Vol.25, No.7, pp.967-1016, 2016
Ortwein R., Ryś M., Skoczeń B., Damage evolution in a stainless steel bar undergoing phase transformation under torsion at cryogenic temperatures, INTERNATIONAL JOURNAL OF DAMAGE MECHANICS, ISSN: 1056-7895, DOI: 10.1177/1056789516656746, Vol.25, No.7, pp.967-1016, 2016

Abstract:
Phase transformation driven by plastic strains is commonly observed in austenitic stainless steels. In the present paper, this phenomenon is addressed in connection with damage evolution. A three-dimensional constitutive model has been derived, and scalar variables for damage and the volume fraction of the transformed phase were used. The model was solved using Abaqus UMAT user defined procedure, as well as by means of simplified one-dimensional approach for a twisted circular bar. Large experimental campaign of tests was performed, including martensite content measurements within the cross-section and on the surface of the bar during monotonic and cyclic loading. Based on the residual angle of twist, damage variable was calculated. The global response of torque versus the angle of twist was measured as well. Comparison between the experimental results and the results obtained from the simplified one-dimensional approach and from the full three-dimensional approach are presented. It turns out that one-dimensional formulation agrees quite well with full three-dimensional model. Thus, much simpler approach can effectively be used. Moreover, experimental results agree well in terms of the martensite content evolution and relation: torque versus the angle of twist. Damage evolution is correctly predicted in terms of the maximum values. Lastly, the evolution of damage during cyclic torsion is discussed, as the experimental results indicate rather surprising effect of unloading modulus recovery after each reversion of twist direction

Keywords:
Cryogenic temperatures, plastic strain-induced phase transformation, torsion, damage evolution, constitutive model, martensite, austenitic stainless steels

106.Górecka K., Skłodowski M., Pawłowski P., Osowicki G., Belgijski pacjent. Polskie prace badawczo – konserwatorskie przy wielkoformatowym krzywoliniowym obrazie z XVIII w. z katedry Saint-Aubain w Namur, , Vol.21, No.80, pp.62-71, 2016
Górecka K., Skłodowski M., Pawłowski P., Osowicki G., Belgijski pacjent. Polskie prace badawczo – konserwatorskie przy wielkoformatowym krzywoliniowym obrazie z XVIII w. z katedry Saint-Aubain w Namur, , Vol.21, No.80, pp.62-71, 2016

Abstract:
Paper discusses a concept and conservation methodology of the XVII. century curvilinear canvas painting "Adoration of the Magi" from the Saint-Aubain Cathedral church in Namur (Belgium). Atypical form of the painting bowed in the horizontal plane, adapted to a, wall and its enormous size (3.70 x 4.50 m) required using some innovative technologies and materials. Restoration work required access to both the face and the back of the picture. But how to overturn the painting? How to strengthen its support? How to tight. it? Such problems can be solved only by the interdisciplinary collaboration of a team of professionals. In this way decisions about the conservation were discussed in the group of experts from various disciplines. The article focuses o! n the problem of curvilinear canvas stretching, which is presented fro m different points of view. In the council participated restorers, scientist and engineers. Finally, we agreed that the basic premise of the conservation process was a detailed analysis of the canvas shape and its preservation on each step of the conservation works. The concept required construction of two curved platforms: concave and convex. The new system of the canvas overturning was also designed. An innovating method of strengthening of the canvas vertical direction during lining process by using Kevlar fibres was applied. The XVII. century stretcher frame was preserved as an example of historical construction. The new stretching system was built out of the original stretcher frame. The conservation works were finished in 2014, the painting was put in the frame and fixed on the wall. The optical analysis of its shape achieved one year after showed that its state is stable.

107.Egner H., Skoczeń B., Ryś M., Constitutive and numerical modeling of coupled dissipative phenomena in 316L stainless steel at cryogenic temperatures, International Journal of Plasticity, ISSN: 0749-6419, DOI: 10.1016/j.ijplas.2014.08.005, Vol.64, pp.113-133, 2015
Egner H., Skoczeń B., Ryś M., Constitutive and numerical modeling of coupled dissipative phenomena in 316L stainless steel at cryogenic temperatures, International Journal of Plasticity, ISSN: 0749-6419, DOI: 10.1016/j.ijplas.2014.08.005, Vol.64, pp.113-133, 2015

Abstract:
A macroscopic material model for simulation of coupled dissipative phenomena taking place in FCC metals and alloys at low temperatures is developed. Three phenomena: plastic flow, plastic strain induced transformation from the parent phase ( to the secondary phase ( and evolution of micro-damage are studied using a thermodynamically consistent framework. The experimental results indicate a correlation between decreasing damage rate and increasing martensite content. For the micro-damage evolution in the parent austenitic phase a generalization of the classical isotropic ductile damage concept to anisotropic model has been adopted. The kinetics of damage evolution is based on the accumulated plastic strain as a driving force of ductile damage. On the other hand, the deterioration of the brittle secondary phase is described by the damage evolution equation expressed in the form of tensorial function, where the damage tensor depends directly on the stresses applied. This formulation accounts both for the isotropic damage, and for the oriented damage due to different effects of the stress tensor. Total amount of damage in the representative volume element is obtained via the linear rule of mixture. The results obtained in the course of numerical simulations fit well the experimental data

Keywords:
B. Constitutive behavior, A. Microcracking, A. Phase transformation, Cryogenic temperature

108.Jansen K.A., Bacabac R.G., Piechocka I.K., Koenderink G.H., Cells actively stiffen fibrin networks by generating contractile stress, BIOPHYSICAL JOURNAL, ISSN: 0006-3495, DOI: 10.1016/j.bpj.2013.10.008, Vol.105, No.10, pp.2240-2251, 2013
Jansen K.A., Bacabac R.G., Piechocka I.K., Koenderink G.H., Cells actively stiffen fibrin networks by generating contractile stress, BIOPHYSICAL JOURNAL, ISSN: 0006-3495, DOI: 10.1016/j.bpj.2013.10.008, Vol.105, No.10, pp.2240-2251, 2013

Abstract:
During wound healing and angiogenesis, fibrin serves as a provisional extracellular matrix. We use a model system of fibroblasts embedded in fibrin gels to study how cell-mediated contraction may influence the macroscopic mechanical properties of their extracellular matrix during such processes. We demonstrate by macroscopic shear rheology that the cells increase the elastic modulus of the fibrin gels. Microscopy observations show that this stiffening sets in when the cells spread and apply traction forces on the fibrin fibers. We further show that the stiffening response mimics the effect of an external stress applied by mechanical shear. We propose that stiffening is a consequence of active myosin-driven cell contraction, which provokes a nonlinear elastic response of the fibrin matrix. Cell-induced stiffening is limited to a factor 3 even though fibrin gels can in principle stiffen much more before breaking. We discuss this observation in light of recent models of fibrin gel elasticity, and conclude that the fibroblasts pull out floppy modes, such as thermal bending undulations, from the fibrin network, but do not axially stretch the fibers. Our findings are relevant for understanding the role of matrix contraction by cells during wound healing and cancer development, and may provide design parameters for materials to guide morphogenesis in tissue engineering.

109.Piechocka I.K., van Oosten A.S.G., Breuls R.G., Koenderink G.H., Rheology of Heterotypic Collagen Networks, BIOMACROMOLECULES, ISSN: 1525-7797, DOI: 10.1021/bm200553x, Vol.12, No.7, pp.2797-2805, 2011
Piechocka I.K., van Oosten A.S.G., Breuls R.G., Koenderink G.H., Rheology of Heterotypic Collagen Networks, BIOMACROMOLECULES, ISSN: 1525-7797, DOI: 10.1021/bm200553x, Vol.12, No.7, pp.2797-2805, 2011

Abstract:
Collagen fibrils are the main structural element of connective tissues. In many tissues, these fibrils contain two fibrillar collagens (types I and V) in a ratio that changes during tissue development, regeneration, and various diseases. Here we investigate the influence of collagen composition on the structure and rheology of networks of purified collagen I and V, combining fluorescence and atomic force microscopy, turbidimetry, and rheometry. We demonstrate that the network stiffness strongly decreases with increasing collagen V content, even though the network structure does not substantially change. We compare the rheological data with theoretical models for rigid polymers and find that the elasticity is dominated by nonaffine deformations. There is no analytical theory describing this regime, hampering a quantitative interpretation of the influence of collagen V. Our findings are relevant for understanding molecular origins of tissue biomechanics and for guiding rational design of collagenous biomaterials for biomedical applications.

110.Piechocka I.K., Bacabac R.G., Potters M., MacKintosh F.C., Koenderink G.H., Structural Hierarchy Governs Fibrin Gel Mechanics, BIOPHYSICAL JOURNAL, ISSN: 0006-3495, DOI: 10.1016/j.bpj.2010.01.040, Vol.98, No.10, pp.2281-2289, 2010
Piechocka I.K., Bacabac R.G., Potters M., MacKintosh F.C., Koenderink G.H., Structural Hierarchy Governs Fibrin Gel Mechanics, BIOPHYSICAL JOURNAL, ISSN: 0006-3495, DOI: 10.1016/j.bpj.2010.01.040, Vol.98, No.10, pp.2281-2289, 2010

Abstract:
Fibrin gels are responsible for the mechanical strength of blood clots, which are among the most resilient protein materials in nature. Here we investigate the physical origin of this mechanical behavior by performing rheology measurements on reconstituted fibrin gels. We find that increasing levels of shear strain induce a succession of distinct elastic responses that reflect stretching processes on different length scales. We present a theoretical model that explains these observations in terms of the unique hierarchical architecture of the fibers. The fibers are bundles of semiflexible protofibrils that are loosely connected by flexible linker chains. This architecture makes the fibers 100-fold more flexible to bending than anticipated based on their large diameter. Moreover, in contrast with other biopolymers, fibrin fibers intrinsically stiffen when stretched. The resulting hierarchy of elastic regimes explains the incredible resilience of fibrin clots against large deformations.

111.Meissner M., The response of Helmholtz resonator to external excitation. Part I: acoustically induced resonance, ARCHIVES OF ACOUSTICS, ISSN: 0137-5075, Vol.29, No.1, pp.107-121, 2004
Meissner M., The response of Helmholtz resonator to external excitation. Part I: acoustically induced resonance, ARCHIVES OF ACOUSTICS, ISSN: 0137-5075, Vol.29, No.1, pp.107-121, 2004

Abstract:
The first of two companion papers theoretical and experimental results are presented for a Helmholtz resonator subject to external excitation by an acoustic plane wave. The response of the resonator was analysed in terms of the relation between the pressure induced in the interior of the resonator and the driving pressure. Equations for the resonance frequency and the quality factor were developed for the cavity that was a rectangular parallelepiped with a centered circular orifice. The flow from the cavity had a constant velocity profile. The resonator was modelled by an equivalent impedance circuit, predicted from the classic theory of sound radiation, with an additional resistive term connected with the viscous action inside the orifice. The theoretical results were compared with experimental data for a frequency chosen so as to tune the system to the lowest resonance mode. The experiment has shown that the acoustic response of resonator was changed considerably when mechanical vibrations of the resonator elements were excited. A phenomenon of flow-induced resonance in the considered system geometry will be presented in the companion paper.

Keywords:
Helmholtz resonator, flow-induced resonanse, acoustic response of resonator

112.Meissner M., Excitation of Helmholtz resonator by grazing air flow, JOURNAL OF SOUND AND VIBRATION, ISSN: 0022-460X, DOI: 10.1006/jsvi.2001.4219, Vol.256, No.2, pp.382-388, 2002
Meissner M., Excitation of Helmholtz resonator by grazing air flow, JOURNAL OF SOUND AND VIBRATION, ISSN: 0022-460X, DOI: 10.1006/jsvi.2001.4219, Vol.256, No.2, pp.382-388, 2002

Keywords:
cavity resonator, flow-excited sound, Strouhal number

113.Meissner M., Aerodynamically excited acoustic oscillations in cavity resonator exposed to an air jet, ACTA ACUSTICA UNITED WITH ACUSTICA, ISSN: 1610-1928, Vol.88, No.2, pp.170-180, 2002
Meissner M., Aerodynamically excited acoustic oscillations in cavity resonator exposed to an air jet, ACTA ACUSTICA UNITED WITH ACUSTICA, ISSN: 1610-1928, Vol.88, No.2, pp.170-180, 2002

Abstract:
Experimental and theoretical results are presented for a cavity resonator driven by an air jet. Cavity sound spectra have been investigated to found a dependence of sound frequency and amplitude versus jet speed. Two ranges of the jet speed were distinguished. In the stage I, identified with low speed range, the frequency increased fast with jet speed and a frequency increment was proportional to jet speed as in the edge–tones phenomenon. In a stage II, corresponding to higher jet speeds, an increase in the frequency was still observed, but a frequency growth was much smaller. A correlation of experimental data has shown that the observed oscillation amplitudes are within moderate–range. A theoretical model based on moving compact vortices was presented to describe flow–acoustic interaction in a resonator opening and find an aerodynamic force driving a resonator. A response of resonator was modelled by equivalent impedance circuit with added nonlinear term. From final equations a frequency and an amplitude of oscillation were calculated. A support for the proposed theory is provided by favourable comparison between theoretical predictions and experimental data.

Keywords:
cavity resonator, air jet, sound generation, vortex street

114.Meissner M., Acoustic modes induced by flow in a pipe with two closed side-branches, APPLIED ACOUSTICS, ISSN: 0003-682X, Vol.63, No.10, pp.1071-1083, 2002
Meissner M., Acoustic modes induced by flow in a pipe with two closed side-branches, APPLIED ACOUSTICS, ISSN: 0003-682X, Vol.63, No.10, pp.1071-1083, 2002

Abstract:
An air flow in a pipe with two closed side-branches can induce high pressure pulsations in a pipe system. This phenomenon has been investigated and the results are reported in this paper. A simple theoretical model based on a wave transmission was used to determine a resonance condition associated with an acoustic coupling between branches. In the model a plane wave approximation and an impedance representation of a branch were applied. The experiment was carried out in a pipe system with a relatively large distance between branches compared to branch lengths. A frequency and a pressure of pulsations were measured in a wide range of length of downstream branch. A support for the theory is provided by a favorable comparison between experimental data and calculated resonant frequencies of the system.

Keywords:
pipe system, closed side-branches, acoustic resonance

115.Meissner M., Absorption properties of Helmholtz resonator at high amplitude incident sound, ACTA ACUSTICA UNITED WITH ACUSTICA, ISSN: 1610-1928, Vol.86, No.6, pp.985-991, 2000
Meissner M., Absorption properties of Helmholtz resonator at high amplitude incident sound, ACTA ACUSTICA UNITED WITH ACUSTICA, ISSN: 1610-1928, Vol.86, No.6, pp.985-991, 2000

Abstract:
The sound attenuation in a Helmholtz resonator subjected to a plane incident wave is examined. The resonator closing a tube is considered. The average acoustic power absorbed by vortical field has been calculated in the low frequency range with the aid of the appropriate conservation equations. Considering this power loss and losses due to viscous damping inside the resonator orifice, the change of absorption properties of the resonator is analyzed. Results of this study indicate that the peak of the absorption coefficient occurs when the loss resistance is equal to the radiation resistance. Plots of the theoretically predicted absorption coefficient and normalized loss resistance as a function of incident pressure amplitude are in good agreement with experimental data obtained for different orifice diameters.

Keywords:
Helmholtz resonator, sound absorption, nonlinear resistance

116.Meissner M., The influence of acoustic nonlinearity on absorption properties of Helmholtz resonators. Part II: experiment, ARCHIVES OF ACOUSTICS, ISSN: 0137-5075, Vol.25, No.2, pp.175-190, 2000
Meissner M., The influence of acoustic nonlinearity on absorption properties of Helmholtz resonators. Part II: experiment, ARCHIVES OF ACOUSTICS, ISSN: 0137-5075, Vol.25, No.2, pp.175-190, 2000

Abstract:
An experimental study of an effect of the acoustic nonlinearity on absorption properties of Helmholtz resonators is presented in this work. By use of the classical standing wave method the changes in the absorption coefficient and the resonators impedance were investigated at moderate and high amplitudes of incident wave. As a result of nonlinearity a high absorption at resonance frequencies was observed and then a decrease in this absorption with increasing amplitude. Measurements of the total loss resistance of resonators have indicated that a change in the resistance at high amplitudes depends strongly on resonator orifice area, the smaller area - the higher increase in the resistance. The experimental results have also shown a growth in resonators reactance which causes an increase in resonance frequency. Quite a good agreement between experimental data and the theory presented in Part I was found.

Keywords:
Helmholtz resonator, acoustic nonlinearity, absorption coefficient

117.Meissner M., The influence of acoustic nonlinearity on absorption properties of Helmholtz resonators. Part I: theory, ARCHIVES OF ACOUSTICS, ISSN: 0137-5075, Vol.24, No.2, pp.179-190, 1999
Meissner M., The influence of acoustic nonlinearity on absorption properties of Helmholtz resonators. Part I: theory, ARCHIVES OF ACOUSTICS, ISSN: 0137-5075, Vol.24, No.2, pp.179-190, 1999

Abstract:
This is the first of two companion papers concerned with the nonlinear absorption of Helmholtz resonators at a high amplitude incident wave. The phenomenon has been examined theoretically by use of a model of the acoustic field in the neighborhood of the resonator placed at the end of cylindrical tube. The calculation results have shown that the peak of the absorption coeficient occurs when the nonlinear resistance is equal to the radiation resistance of the resonator. The full experimental investigations of this phenomenon and a comparison between theoretical and experimental data will be presented in the companion paper (Part II).

Keywords:
Helmholtz resonator, nonlinear sound absorption, high amplitude incident sound

118.Meissner M., Flow–excited acoustic pulsations in ducts with closed side branches, ARCHIVES OF ACOUSTICS, ISSN: 0137-5075, Vol.22, No.2, pp.153-167, 1997
Meissner M., Flow–excited acoustic pulsations in ducts with closed side branches, ARCHIVES OF ACOUSTICS, ISSN: 0137-5075, Vol.22, No.2, pp.153-167, 1997

Abstract:
In flow ducts with closed side branches strong acoustic pulsations are often induced. This was shown by test results performed for systems with a single side branch and co-axial branches with the same lengths. With growing the flow velocity an excitation of successive resonant modes was observed. Their frequencies were increased together with the flow velocity but at peaks of sound pressure there was an excellent agreement between measurements results and theoretical predictions. A conversion of fluctuating flow energy to energy of resonant acoustic field was included in theoretical consideration by means of negative resistance in impedance model of branches. Hence, it was possible to predict a stronger nonlinearity in the case of a duct with co-axial branches. It was found that a characteristic parameter of the analyzed phenomenon is Strouhal number. Its values for all modes are within the same range approximately and, in addition, it determines a change of acoustic inertance at the branch opening.

Keywords:
closed side branches, Strouhal number, resonant modes

119.Meissner M., Czechowicz M., Experimental investigation of flow-induced acoustic oscillations in piping system with closed branches, APPLIED ACOUSTICS, ISSN: 0003-682X, Vol.45, No.4, pp.359-375, 1995
Meissner M., Czechowicz M., Experimental investigation of flow-induced acoustic oscillations in piping system with closed branches, APPLIED ACOUSTICS, ISSN: 0003-682X, Vol.45, No.4, pp.359-375, 1995

Abstract:
An experimental study of flow-excited acoustic oscillations in piping systems with closed branches is presented in this paper. An influence of acoustic interactions between branches on a generated sound was investigated in arrangements with two and three branches. Significant changes of frequency and level of oscillation in terms of branch lengths were observed. In the system with three branches, at the specified lengths of one branch, a cancellation of oscillations was noticed.

Keywords:
piping system, closed side branches, flow-induced oscillations

120.Meissner M., Ranachowski Z., Modelling of acoustic emission sources, ACTA ACUSTICA UNITED WITH ACUSTICA, ISSN: 1610-1928, Vol.79, No.2, pp.186-189, 1993
Meissner M., Ranachowski Z., Modelling of acoustic emission sources, ACTA ACUSTICA UNITED WITH ACUSTICA, ISSN: 1610-1928, Vol.79, No.2, pp.186-189, 1993

Keywords:
acoustic emission, plate vibrations, frequency spectrum

121.Meissner M., Discrete sound induced by low Mach number flow over side branch deep cavity in a rectangular duct, ARCHIVES OF ACOUSTICS, ISSN: 0137-5075, Vol.17, No.2, pp.287-305, 1992
Meissner M., Discrete sound induced by low Mach number flow over side branch deep cavity in a rectangular duct, ARCHIVES OF ACOUSTICS, ISSN: 0137-5075, Vol.17, No.2, pp.287-305, 1992

Abstract:
This paper presents the model of the discrete sound induction effect due to a flow over deep cavity in the wall of a rectangular duct. Theoretical analysis applies shear layer approximation with a vortex sheet, with deflection satisfying the Kutta-Żukowski condition, and an equivalent impedance system of a deep cavity with cavity impedance change in the presence of the flow included. The applied theoreticl method makes it possible to determine the effect of resonanse modes of the cavity on disturbances of the vortex sheet and also to determine the frequency and relative value of pressure amplitude in the case of a discrete sound.

Keywords:
discrete sound generation, vortex sheet, deep cavity

122.Meissner M., Self-sustained deep cavity oscillations induced by grazing flow, ACTA ACUSTICA UNITED WITH ACUSTICA, ISSN: 1610-1928, Vol.62, No.3, pp.220-228, 1987
Meissner M., Self-sustained deep cavity oscillations induced by grazing flow, ACTA ACUSTICA UNITED WITH ACUSTICA, ISSN: 1610-1928, Vol.62, No.3, pp.220-228, 1987

Abstract:
This paper is concerned with a model of sound generation in a case of the deep cavity exposed to a grazing mean air flow. The problem was analyzed theoretically by means of infinitely thin shear layer assumption and the description of acoustic response of the cavity. The response was determined with the aid of the impedance model of flow excited quarter-wave resonator, including the nonlinear orifice damping. The parameters of unstable motion in the slot were found, basing on continuity conditions across the orifice plane. Calculated values were used in order to determine the acoustic pressure in far-field area. The theoretical predictions were compared to experimental results.

Keywords:
deep cavity, discrete sound generation, grazing flow