Publikacje odnotowane przez trzy miesiące

1.Dziekoński C., Dera W., Jarząbek D.M., Method for lateral force calibration in atomic force microscope using MEMS microforce sensor, ULTRAMICROSCOPY, ISSN: 0304-3991, DOI: 10.1016/j.ultramic.2017.06.012, Vol.182, pp.1-9, 2017
Dziekoński C., Dera W., Jarząbek D.M., Method for lateral force calibration in atomic force microscope using MEMS microforce sensor, ULTRAMICROSCOPY, ISSN: 0304-3991, DOI: 10.1016/j.ultramic.2017.06.012, Vol.182, pp.1-9, 2017

Abstract:
In this paper we present a simple and direct method for the lateral force calibration constant determination. Our procedure does not require any knowledge about material or geometrical parameters of an investigated cantilever. We apply a commercially available microforce sensor with advanced electronics for direct measurement of the friction force applied by the cantilever's tip to a flat surface of the microforce sensor measuring beam. Due to the third law of dynamics, the friction force of the equal value tilts the AFM cantilever. Therefore, torsional (lateral force) signal is compared with the signal from the microforce sensor and the lateral force calibration constant is determined. The method is easy to perform and could be widely used for the lateral force calibration constant determination in many types of atomic force microscopes.

Keywords:
A precise and direct method for lateral force calibration, Inaccuracy equal to approximately 2%, Wedge method is proven to give inaccurate results

(50p.)
2.Majewski M., Kursa M., Hołobut P., Kowalczyk-Gajewska K., Micromechanical and numerical analysis of packing and size effects in elastic particulate composites, COMPOSITES PART B-ENGINEERING, ISSN: 1359-8368, DOI: 10.1016/j.compositesb.2017.05.004, Vol.124, pp.158-174, 2017
Majewski M., Kursa M., Hołobut P., Kowalczyk-Gajewska K., Micromechanical and numerical analysis of packing and size effects in elastic particulate composites, COMPOSITES PART B-ENGINEERING, ISSN: 1359-8368, DOI: 10.1016/j.compositesb.2017.05.004, Vol.124, pp.158-174, 2017

Abstract:
Effects of particle packing and size on the overall elastic properties of particulate random composites are analyzed. In order to account for the two effects the mean-field Morphologically Representative Pattern (MRP) approach is employed and an additional interphase surrounding inclusions (coating) is introduced. The analytical mean-field estimates are compared with the results of computational homogenization performed using the finite element (FE) method. Periodic unit cells with cubic crystal-type arrangements and representative volume elements with random distributions of particles are used for verification purposes. The validity of the MRP estimates with respect to the FE results is assessed.

Keywords:
Composite materials, Elasticity, Micro-mechanics, Packing and size effects

(45p.)
3.Pierini F., Lanzi M., Nakielski P., Pawłowska S., Urbanek O., Zembrzycki K., Kowalewski T.A., Single-Material Organic Solar Cells Based on Electrospun Fullerene-Grafted Polythiophene Nanofibers, Macromolecules, ISSN: 0024-9297, DOI: 10.1021/acs.macromol.7b00857, pp.1-10, 2017
Pierini F., Lanzi M., Nakielski P., Pawłowska S., Urbanek O., Zembrzycki K., Kowalewski T.A., Single-Material Organic Solar Cells Based on Electrospun Fullerene-Grafted Polythiophene Nanofibers, Macromolecules, ISSN: 0024-9297, DOI: 10.1021/acs.macromol.7b00857, pp.1-10, 2017

Abstract:
Highly efficient single-material organic solar cells (SMOCs) based on fullerene-grafted polythiophenes were fabricated by incorporating electrospun one-dimensional (1D) nanostructures obtained from polymer chain stretching. Poly(3-alkylthiophene) chains were chemically tailored in order to reduce the side effects of charge recombination which severely affected SMOC photovoltaic performance. This enabled us to synthesize a donor–acceptor conjugated copolymer with high solubility, molecular weight, regioregularity, and fullerene content. We investigated the correlations among the active layer hierarchical structure given by the inclusion of electrospun nanofibers and the solar cell photovoltaic properties. The results indicated that SMOC efficiency can be strongly increased by optimizing the supramolecular and nanoscale structure of the active layer, while achieving the highest reported efficiency value (PCE = 5.58%). The enhanced performance may be attributed to well-packed and properly oriented polymer chains. Overall, our work demonstrates that the active material structure optimization obtained by including electrospun nanofibers plays a pivotal role in the development of efficient SMOCs and suggests an interesting perspective for the improvement of copolymer-based photovoltaic device performance using an alternative pathway.

(45p.)
4.Pieczyska E.A., Staszczak M., Kowalczyk-Gajewska K., Maj M., Golasiński K., Golba S., Tobushi H., Hayashi S., Experimental and numerical investigation of yielding phenomena in a shape memory polymer subjected to cyclic tension at various strain rates, POLYMER TESTING, ISSN: 0142-9418, DOI: 10.1016/j.polymertesting.2017.04.014, Vol.60, pp.333-342, 2017
Pieczyska E.A., Staszczak M., Kowalczyk-Gajewska K., Maj M., Golasiński K., Golba S., Tobushi H., Hayashi S., Experimental and numerical investigation of yielding phenomena in a shape memory polymer subjected to cyclic tension at various strain rates, POLYMER TESTING, ISSN: 0142-9418, DOI: 10.1016/j.polymertesting.2017.04.014, Vol.60, pp.333-342, 2017

Abstract:
This paper presents experimental and numerical results of a polyurethane shape memory polymer (SMP) subjected to cyclic tensile loading. The goal was to investigate the polymer yielding phenomena based on the effects of thermomechanical coupling. Mechanical characteristics were obtained with a testing machine, whereas the SMP temperature accompanying its deformation process was simultaneously measured in a contactless manner with an infrared camera. The SMP glass transition temperature was approximately 45oC; therefore, when tested at room temperature, the polymer is rigid and behaves as solid material. The stress and related temperature changes at various strain rates showed how the SMP yield limit evolved in subsequent loading-unloading cycles under various strain rates. A two-phase model of the SMP was applied to describe its mechanical response in cyclic tension. The 3D Finite Element model of a tested specimen was used in simulations. Good agreement between the model predictions and experimental results was observed for the first tension cycle.

Keywords:
Shape memory polymer, Tension cyclic loading, Thermomechanical coupling, Yield limit, Thermoelastic effect, Constitutive model

(40p.)
5.Zajączkowska U., Kucharski S., Nowak Z., Grabowska K., Morphometric and mechanical characteristics of Equisetum hyemale stem enhance its vibration, PLANTA, ISSN: 0032-0935, DOI: DOI 10.1007/s00425-017-2648-1, Vol.245, No.4, pp.835-848, 2017
Zajączkowska U., Kucharski S., Nowak Z., Grabowska K., Morphometric and mechanical characteristics of Equisetum hyemale stem enhance its vibration, PLANTA, ISSN: 0032-0935, DOI: DOI 10.1007/s00425-017-2648-1, Vol.245, No.4, pp.835-848, 2017

Abstract:
The order of the internodes, and their geometry and mechanical characteristics influence the capability of theEquisetumstem to vibrate, potentially stimulating spore liberation at the optimum stress setting along the stem.
Equisetum hyemale L. plants represent a special example of cellular solid construction with mechanical stability achieved by a high second moment of area and relatively high resistance against local buckling. We proposed the hypothesis that the order of E. hyemale L. stem internodes, their geometry and mechanical characteristics influence the capability of the stem to vibrate, stimulating spore liberation at the minimum stress setting value along the stem. An analysis of apex vibration was done based on videos presenting the behavior of an Equisetum clump filmed in a wind tunnel and also as a result of excitation by bending the stem by 20°. We compared these data with the vibrations of stems of the same size but deprived of the three topmost internodes. Also, we created a finite element model (FEM), upon which we have based the ‘natural’ stem vibration as a copy of the real object, ‘random’ with reshuffled internodes and ‘uniform’, created as one tube with the characters averaged from all internodes. The natural internode arrangement influences the frequency and amplitude of the apex vibration, maintaining an equal stress distribution in the stem, which may influence the capability for efficient spore spreading.

Keywords:
Mechanical properties, Plant biomechanics, Segmented structure, Stem vibration, Stress distribution, Wind

(40p.)
6.Makowska K., Piotrowski L., Kowalewski Z.L., Prediction of the Mechanical Properties of P91 Steel by Means of Magneto-acoustic Emission and Acoustic Birefringence, JOURNAL OF NONDESTRUCTIVE EVALUATION, ISSN: 0195-9298, DOI: 10.1007/s10921-017-0421-9, Vol.36, No.2, pp.43/1-43/10, 2017
Makowska K., Piotrowski L., Kowalewski Z.L., Prediction of the Mechanical Properties of P91 Steel by Means of Magneto-acoustic Emission and Acoustic Birefringence, JOURNAL OF NONDESTRUCTIVE EVALUATION, ISSN: 0195-9298, DOI: 10.1007/s10921-017-0421-9, Vol.36, No.2, pp.43/1-43/10, 2017

Abstract:
The paper describes an application of non-destructive volumetric magnetic and ultrasonic techniques for evaluation of the selected mechanical parameter variations of P91 steel having direct influence on its suitability for further use in critical components used in power plants. Two different types of deformation processes were carried out. First, a series of the P91 steel specimens was subjected to creep and second, one to plastic deformation in order to achieve the material with an increasing strain level up to 10%. Subsequently, non-destructive and destructive tests were performed. Magnetic methods based on measurements of magnetoacoustic emission and magnetic hysteresis loop changes as well as the ultrasonic method based on acoustic birefringence measurements, were applied. Finally, the static tensile tests were carried out in order to evaluate the mechanical parameters. It is shown that some relationships between the selected parameters coming from the non-destructive and destructive tests may be formulated.

Keywords:
Creep, Plastic deformation, Acoustic birefringence, Magnetoacoustic emission, Magnetic hysteresis loop

(35p.)
7.Guzik M.N., Golasiński K.M., Pedrosa F.J., Jenuš P., Bollero A., Hauback B.C., Deledda S., Influence of ultra-short cryomilling on the microstructural andmagnetic properties of cobalt ferrite, JOURNAL OF ALLOYS AND COMPOUNDS, ISSN: 0925-8388, DOI: 10.1016/j.jallcom.2017.05.290, Vol.721, pp.440-448, 2017
Guzik M.N., Golasiński K.M., Pedrosa F.J., Jenuš P., Bollero A., Hauback B.C., Deledda S., Influence of ultra-short cryomilling on the microstructural andmagnetic properties of cobalt ferrite, JOURNAL OF ALLOYS AND COMPOUNDS, ISSN: 0925-8388, DOI: 10.1016/j.jallcom.2017.05.290, Vol.721, pp.440-448, 2017

Abstract:
The impact of ultra-short milling at liquid nitrogen temperatures on structural and magnetic properties of cobalt ferrite (CoFe2O4) powders has been explored for the first time. Cryomilling for only up to 9 min increases the coercivity of the isotropic powder from 139 to 306 kA/m (1.74–3.85 kOe) and results in its modifications comparable with milling for hours at room temperature. A thermal treatment of processed CoFe2O4 enables further optimization of powder magnetic properties and leads to a high value of energy product (13.5 kJ/m3) for the sample treated at 600 °C. Systematic studies, comprising analysis of structural and microstructural properties, based on synchrotron powder X-ray diffraction, scanning and transmission electron microscopy demonstrate the high efficiency of cryomilling in reduction of crystallite sizes and formation of lattice strain in the processed cobalt ferrite samples.

Keywords:
Cryomilling, Cobalt ferrite, Magnetic properties

(35p.)
8.Graczykowski C., Pawłowski P., Exact physical model of magnetorheological damper, Applied Mathematical Modelling, ISSN: 0307-904X, DOI: https://doi.org/10.1016/j.apm.2017.02.035, Vol.47, pp.400-424, 2017
Graczykowski C., Pawłowski P., Exact physical model of magnetorheological damper, Applied Mathematical Modelling, ISSN: 0307-904X, DOI: https://doi.org/10.1016/j.apm.2017.02.035, Vol.47, pp.400-424, 2017

Abstract:
This paper attempts to fill the gap in the literature by introducing and discussing an enhanced physical model of the MR damper. The essence of the presented model is to combine the effect of compressibility of the MR fluid enclosed in each chamber with the effect of blocking the flow between the chambers in the case of a low pressure difference. As it will be shown, the concurrence of both considered phenomena significantly affects mechanical behaviour of the damper, influences its dissipative characteristics, and in particular, it is the reason behind the distinctive ‘z-shaped’ force–velocity hysteresis loops observed in experiments. The paper presents explanation of the observed phenomena, detailed derivation of the thermodynamic equations governing response of the damper, their implementation for various constitutive models of the magnetorheological fluid and, finally, formulation of the corresponding reduced and parametric models. Experimental validation shows that proper identification of physical parameters of the proposed mathematical model yields the correct shapes of force–velocity hysteresis loops.

Keywords:
Magnetorheological fluid dampers, Smart fluids, Hysteresis modelling

(35p.)
9.Nosewicz S., Rojek J., Chmielewski M., Pietrzak K., Discrete element modeling and experimental investigation of hot pressing of intermetallic NiAl powder, ADVANCED POWDER TECHNOLOGY, ISSN: 0921-8831, DOI: 10.1016/j.apt.2017.04.012, Vol.28, pp.1745-1759, 2017
Nosewicz S., Rojek J., Chmielewski M., Pietrzak K., Discrete element modeling and experimental investigation of hot pressing of intermetallic NiAl powder, ADVANCED POWDER TECHNOLOGY, ISSN: 0921-8831, DOI: 10.1016/j.apt.2017.04.012, Vol.28, pp.1745-1759, 2017

Abstract:
This paper presents the numerical and experimental analysis of hot pressing of NiAl powder with an emphasis on the best possible representation of its main stages: initial powder compaction and pressure-assisted sintering. The numerical study has been performed within the discrete element framework. In the paper, an original viscoelastic model of hot pressing has been used. In order to ensure that the applied values of material parameters in numerical simulations are appropriate, the reference literature has been reviewed. It produced the relations and equations to estimate the values of all required sintering material parameters of the considered viscoelastic model. Numerical simulations have employed the geometrical model of the initial dense specimen generated by a special algorithm which uses the real grain distribution of powder. The numerical model has been calibrated and validated through simulations of the real process of hot pressing of intermetallic NiAl material. The kinetics of compaction, sintering and cooling stage indicated by the evolution of density, shrinkage and densification rate have been studied. The comparison of numerical and experimental results has shown a good performance of the developed numerical model.

Keywords:
Powder metallurgy; Hot pressing; Sintering; Simulation; Discrete element method; Nickel aluminide

(30p.)
10.Żołek N., Ranachowski Z., Ranachowski P., Jóźwiak-Niedźwiedzka D., Kúdela Jr. S., Dvorak T., Statistical assessment of the microstructure of barite aggregate from different deposits using x-ray microtomography and optical microscopy, ARCHIVES OF METALLURGY AND MATERIALS, ISSN: 1733-3490, DOI: 10.1515/amm-2017-0104, Vol.62, No.2, pp.697-702, 2017
Żołek N., Ranachowski Z., Ranachowski P., Jóźwiak-Niedźwiedzka D., Kúdela Jr. S., Dvorak T., Statistical assessment of the microstructure of barite aggregate from different deposits using x-ray microtomography and optical microscopy, ARCHIVES OF METALLURGY AND MATERIALS, ISSN: 1733-3490, DOI: 10.1515/amm-2017-0104, Vol.62, No.2, pp.697-702, 2017

Abstract:
Two different barite ore (barium sulfate BaSO4) specimens from different localizations were tested and described in this paper. Analysis of the microstructure was performed on polished sections, and on thin sections using X-ray microtomography (micro-CT), and optical microscopy (MO). Microtomography allowed obtaining three-dimensional images of the barite aggregate specimens. In the tomograms, the spatial distribution of the other polluting phases, empty space as well as cracks, pores, and voids – that exceeded ten micrometers of diameter-were possible to visualize. Also, the micro-CT allowed distinguishing between minerals of different density, like SiO2 and BaSO4. Images obtained and analyzed on thin sections with various methods using the optical microscopy in transmitted light delivered additional information on the aggregate microstructure, i.e. allow for estimation of the different kinds of inclusions (like the different density of the minerals) in the investigated specimens. Above methods, which were used in the tests, completed each another in order to supply a set of information on inclusions’ distribution and to present the important differences of the barite aggregate specimens microstructure.

Keywords:
barite ore, barite aggregate, microstructure, optical microscopy, thin sections analysis, X-ray tomography

(30p.)
11.Mackiewicz M., Mikulski J.L., Wańkowicz J., Kucharski S., Ranachowski P., Ranachowski Z., Study of composite insulator sheds subjected to wheel test, ARCHIVES OF METALLURGY AND MATERIALS, ISSN: 1733-3490, DOI: 10.1515/amm-2017-0101, Vol.62, No.2, pp.679-686, 2017
Mackiewicz M., Mikulski J.L., Wańkowicz J., Kucharski S., Ranachowski P., Ranachowski Z., Study of composite insulator sheds subjected to wheel test, ARCHIVES OF METALLURGY AND MATERIALS, ISSN: 1733-3490, DOI: 10.1515/amm-2017-0101, Vol.62, No.2, pp.679-686, 2017

Abstract:
The paper presents investigation of the properties of the surface and the material stiffness – flexibility of series of samples taken from the sheds of the composite insulators. The insulators were previously subjected to wheel test. The wheel test and 1000 h salt fog test are regarded as alternative examination of the material resistance to the effects of electrical surface discharges. There were investigated two series of the samples of the composite insulators sheds. Examined specimens, made of HTV silicone rubber, were taken from the sheds of medium-voltage composite insulators of two different manufacturers. Insulators of both types passed the 1000 h salt fog test without reservation. Meanwhile, the wheel test can provide a basis for better distinguishing between physical properties of the tested materials. In the case of the insulators of one of the manufacturers the wheel test result was negative. Cross puncture effect of the sheds took place in several places. In addition, sheds were covered with dark coating of varying thicknesses. The results of the study indicated a significantly stronger influence of electrical and temperature factors on the sheds under investigations during the wheel test than in the case of the 1000 h salt fog test. It can be stated that these tests cannot be considered as alternative and it seems that wheel test enables better distinguishing between properties of the materials.

Keywords:
composite insulators, silicone rubber, wheel test, electrical surface discharges, tracking and erosion

(30p.)
12.Łazarska M., Woźniak T.Z., Ranachowski Z., Ranachowski P., Trafarski A., The application of acoustic emission and artificial neural networks in an analysis of kinetics in the phase transformation of tool steel during austempering, ARCHIVES OF METALLURGY AND MATERIALS, ISSN: 1733-3490, DOI: 10.1515/amm-2017-0089, Vol.62, No.2, pp.603-609, 2017
Łazarska M., Woźniak T.Z., Ranachowski Z., Ranachowski P., Trafarski A., The application of acoustic emission and artificial neural networks in an analysis of kinetics in the phase transformation of tool steel during austempering, ARCHIVES OF METALLURGY AND MATERIALS, ISSN: 1733-3490, DOI: 10.1515/amm-2017-0089, Vol.62, No.2, pp.603-609, 2017

Abstract:
During the course of the study it involved tool steel C105U was used. The steel was austempered at temperatures of 130°C, 160°C and 180°C respectively. Methods of acoustic emission (AE) were used to investigate the resulting effects associated with transformations and a large number of AE events were registered. Neural networks were applied to analyse these phenomena. In the tested signal, three groups of events were identified of: high, medium and low energy. The average spectral characteristics enabled the power of the signal spectrum to be determined. After completing the process, the results were compiled in the form of diagrams of the relationship of the AE incidence frequency as a function of time. Based on the results, it was found that in the austempering of tool steel, in the first stage of transformation midrib morphology is formed. Midrib is a twinned thin plate martensite. In the 2nd stage of transformation, the intensity of the generation of medium energy events indicates the occurrence of bainite initialised by martensite. The obtained graphic of AE characteristics of tool steel austempering allow conclusions to be drawn about the kinetics and the mechanism of this transformation.

Keywords:
carbon steel, austempering, lower bainite, acoustic emission (AE), neural networks

(30p.)
13.Chmielewski M., Pietrzak K., Strojny-Nędza A., Jarząbek D., Nosewicz S., Investigations of interface properties in copper-silicon carbide composites, ARCHIVES OF METALLURGY AND MATERIALS, ISSN: 1733-3490, DOI: 10.1515/amm-2017-0200, Vol.62, No.2B, pp.1315-1318, 2017
Chmielewski M., Pietrzak K., Strojny-Nędza A., Jarząbek D., Nosewicz S., Investigations of interface properties in copper-silicon carbide composites, ARCHIVES OF METALLURGY AND MATERIALS, ISSN: 1733-3490, DOI: 10.1515/amm-2017-0200, Vol.62, No.2B, pp.1315-1318, 2017

Abstract:
This paper analyses the technological aspects of the interface formation in the copper-silicon carbide composite and its effect on the material’s microstructure and properties. Cu-SiC composites with two different volume content of ceramic reinforcement were fabricated by hot pressing (HP) and spark plasma sintering (SPS) technique. In order to protect SiC surface from its decomposition, the powder was coated with a thin tungsten layer using plasma vapour deposition (PVD) method. Microstructural analyses provided by scanning electron microscopy revealed the significant differences at metal-ceramic interface. Adhesion force and fracture strength of the interface between SiC particles and copper matrix were measured. Thermal conductivity of composites was determined using laser flash method. The obtained results are discussed with reference to changes in the area of metal-ceramic boundary.

Keywords:
copper matrix composites, silicon carbide, interface, thermal conductivity, adhesion

(30p.)
14.Strojny-Nędza A., Pietrzak K., Teodorczyk M., Basista M., Węglewski W., Chmielewski M., Influence of Material Ccating on the heat Transfer in a layered Cu-SiC-Cu Systems, ARCHIVES OF METALLURGY AND MATERIALS, ISSN: 1733-3490, DOI: 10.1515/amm-2017-0199, Vol.62, No.2B, pp.1311-1314, 2017
Strojny-Nędza A., Pietrzak K., Teodorczyk M., Basista M., Węglewski W., Chmielewski M., Influence of Material Ccating on the heat Transfer in a layered Cu-SiC-Cu Systems, ARCHIVES OF METALLURGY AND MATERIALS, ISSN: 1733-3490, DOI: 10.1515/amm-2017-0199, Vol.62, No.2B, pp.1311-1314, 2017

Abstract:
This paper describes the process of obtaining Cu-SiC-Cu systems by way of spark plasma sintering. A monocrystalline form of silicon carbide (6H-SiC type) was applied in the experiment. Additionally, silicon carbide samples were covered with a layer of tungsten and molybdenum using chemical vapour deposition (CVD) technique. Microstructural examinations and thermal properties measurements were performed. A special attention was put to the metal-ceramic interface. During annealing at a high temperature, copper reacts with silicon carbide. To prevent the decomposition of silicon carbide two types of coating (tungsten and molybdenum) were applied. The effect of covering SiC with the aforementioned elements on the composite’s thermal conductivity was analyzed. Results were compared with the numerical modelling of heat transfer in Cu-SiC-Cu systems. Certain possible reasons behind differences in measurements and modelling results were discussed.

Keywords:
copper matrix composites, silicon carbide, interface, thermal conductivity, modelling

(30p.)
15.Białecki S., Kaźmierczak B., Nowicka D., Tsai J.-C., Regularity of solutions to a reaction–diffusion equation on the sphere: the Legendre series approach, MATHEMATICAL METHODS IN THE APPLIED SCIENCES, ISSN: 0170-4214, DOI: 10.1002/mma.4390, pp.1-21, 2017
Białecki S., Kaźmierczak B., Nowicka D., Tsai J.-C., Regularity of solutions to a reaction–diffusion equation on the sphere: the Legendre series approach, MATHEMATICAL METHODS IN THE APPLIED SCIENCES, ISSN: 0170-4214, DOI: 10.1002/mma.4390, pp.1-21, 2017

Abstract:
In the paper, we study some ‘a priori’ properties of mild solutions to a single reaction–diffusion equation with discontinuous nonlinear reaction term on the two-dimensional sphere close to its poles. This equation is the counterpart of the well-studied bistable reaction–diffusion equation on the Euclidean plane. The investigation of this equation on the sphere is mainly motivated by the phenomenon of the fertilization of oocytes or recent studies of wave propagation in a model of immune cells activation, in which the cell is modeled by a ball. Because of the discontinuous nature of reaction kinetics, the standard theory cannot guarantee the solution existence and its smoothness properties. Moreover, the singular nature of the diffusion operator near the north/south poles makes the analysis more involved. Unlike the case in the Euclidean plane, the (axially symmetric) Green's function for the heat operator on the sphere can only be represented by an infinite series of the Legendre polynomials. Our approach is to consider a formal series in Legendre polynomials obtained by assuming that the mild solution exists. We show that the solution to the equation subject to the Neumann boundary condition is C1 smooth in the spatial variable up to the north/south poles and Hölder continuous with respect to the time variable. Our results provide also a sort of ‘a priori’ estimates, which can be used in the existence proofs of mild solutions, for example, by means of the iterative methods.

Keywords:
discontinuous reaction term, stationary fronts, sphere

(25p.)
16.Mayerberger E.A., Urbanek O., McDaniel R.M., Street R.M., Barsoum M.W., Schauer C.L., Preparation and characterization of polymer-Ti3C2Tx(MXene) composite nanofibers produced via electrospinning, JOURNAL OF APPLIED POLYMER SCIENCE, ISSN: 0021-8995, DOI: 10.1002/app.45295, pp.1-7, 2017
Mayerberger E.A., Urbanek O., McDaniel R.M., Street R.M., Barsoum M.W., Schauer C.L., Preparation and characterization of polymer-Ti3C2Tx(MXene) composite nanofibers produced via electrospinning, JOURNAL OF APPLIED POLYMER SCIENCE, ISSN: 0021-8995, DOI: 10.1002/app.45295, pp.1-7, 2017

Abstract:
MXene, a recently-discovered family of two-dimensional (2 D) transition metal carbides and/or nitrides, have attracted much interest because of their unique electrical, thermal, and mechanical properties. In this study, poly(acrylic acid) (PAA), polyethylene oxide (PEO), poly(vinyl alcohol) (PVA), and alginate/PEO were electrospun with delaminated Ti3C2 (MXene) flakes. The effect of small additions of delaminated Ti3C2 (1% w/w) on the structure and properties of the nanofibers were investigated and compared with those of the neat polymer nanofibers using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FT-IR). Ti3C2 had an effect on the solution properties of the polymer and a greater effect on the average fiber diameter. The Ti3C2Tx/PEO solution exhibited the largest change in viscosity and conductivity with an 11% and 73.6% increase over the base polymer, respectively. X-ray diffractograms demonstrated a high degree of crystallization for Ti3C2/PEO and a slight decrease in crystallinity for Ti3C2/PVA.

Keywords:
composite nanofibers, electrospinning, MXene

(25p.)
17.Sławianowski J.J., Kovalchuk V., Gołubowska B., Martens A., Rożko E.E., Quantized mechanics of affinely-rigid bodies, MATHEMATICAL METHODS IN THE APPLIED SCIENCES, ISSN: 0170-4214, DOI: 10.1002/mma.4501, pp.1-19, 2017
Sławianowski J.J., Kovalchuk V., Gołubowska B., Martens A., Rożko E.E., Quantized mechanics of affinely-rigid bodies, MATHEMATICAL METHODS IN THE APPLIED SCIENCES, ISSN: 0170-4214, DOI: 10.1002/mma.4501, pp.1-19, 2017

Abstract:
In this paper, we develop the main ideas of the quantized version of affinely rigid (homogeneously deformable) motion. We base our consideration on the usual Schrödinger formulation of quantum mechanics in the configurationmanifold, which is given, in our case, by the affine group or equivalently by the semi-direct product of the linear group GL(n,R) and the space of translations R^n, where n equals the dimension of the “physical space.” In particular, we discuss the problem of dynamical invariance of the kinetic energy under the action of the whole affine group, not only under the isometry subgroup. Technically, the treatment is based on the 2-polar decomposition of the matrix of the internal configuration and on the Peter-Weyl theory of generalized Fourier series on Lie groups. One can hope that our results may be applied in quantum problems of elastic media and microstructured continua.

Keywords:
Homogeneously deformable body, Peter-Weyl analysis, Schrödinger quantization.

(25p.)
18.Kúdela Jr. S., Švec P., Bajana O., Orovčík L., Ranachowski P., Ranachowski Z., Saffil alumina fibers reinforced dual-phase Mg-Li and Mg-Li-Zn alloys, KOVOVE MATERIALY-METALLIC MATERIALS, ISSN: 0023-432X, DOI: 10.4149/km 2017 3 195, Vol.55, pp.195-203, 2017
Kúdela Jr. S., Švec P., Bajana O., Orovčík L., Ranachowski P., Ranachowski Z., Saffil alumina fibers reinforced dual-phase Mg-Li and Mg-Li-Zn alloys, KOVOVE MATERIALY-METALLIC MATERIALS, ISSN: 0023-432X, DOI: 10.4149/km 2017 3 195, Vol.55, pp.195-203, 2017

Abstract:
The gas pressure infiltration technique was used to prepare Saffil alumina fibers reinforced Mg-Li and Mg-Li-Zn matrix composites with a dual-phase matrix structure. There was investigated the effect of variable Li content (6.2–10.3 wt.% Li) and Zn alloying (∼ 1.5 wt.% Zn) on the proof stress Rp0.2 of prepared composites. Rp0.2 values increased monotonously with rising fraction of Saffil fibers (5, 10 and 15 vol.%) reaching the maximum of about 250 MPa for Mg-Li matrix composites. Rp0.2 values of Mg-Li-Zn matrix composites were lower. Strengthening effect of Saffil fibers was promoted by the displacement redox reaction with Mg-Li and Mg-Li-Zn melts in which only Li significantly participated. Zn alloying retarded the displacement redox reaction. Too extensive reaction, however, resulted in the fiber damage and the drop in composite strength.

Keywords:
Mg-Li alloys, Saffil fibers, metal matrix composites, short-fiber strengthening, reactive wetting, displacement reactions

(20p.)
19.Kukla D., Brynk T., Pakieła Z., Assessment of Fatigue Resistance of Aluminide Layers on MAR 247 Nickel Super Alloy with Full-Field Optical Strain Measurements, Journal of Materials Engineering and Performance, ISSN: 1059-9495, DOI: 10.1007/s11665-017-2767-7, pp.1-12, 2017
Kukla D., Brynk T., Pakieła Z., Assessment of Fatigue Resistance of Aluminide Layers on MAR 247 Nickel Super Alloy with Full-Field Optical Strain Measurements, Journal of Materials Engineering and Performance, ISSN: 1059-9495, DOI: 10.1007/s11665-017-2767-7, pp.1-12, 2017

Abstract:
This work presents the results of fatigue tests of MAR 247 alloy flat specimens with aluminides layers of 20 or 40 µm thickness obtained in CVD process. Fatigue test was conducted at amplitude equal to half of maximum load and ranging between 300 and 650 MPa (stress asymmetry ratio R = 0, frequency f = 20 Hz). Additionally, 4 of the tests, characterized by the highest amplitude, were accompanied with non-contact strain field measurements by means of electronic speckle pattern interferometry and digital image correlation. Results of these measurements allowed to localize the areas of deformation concentration identified as the damage points of the surface layer or advanced crack presence in core material. Identification and observation of the development of deformation in localization areas allowed to assess fatigue-related phenomena in both layer and substrate materials.

Keywords:
aluminide layer, fatigue testing, full-field optical strain measurements, super nickel alloy

(20p.)
20.Błachowski B.D., Tauzowski P., Lógó J., Modal Approximation Based Optimal Design of Dynamically Loaded Plastic Structures, Periodica Polytechnica Civil Engineering, ISSN: 0553-6626, DOI: 10.3311/PPci.11016, pp.1-6, 2017
Błachowski B.D., Tauzowski P., Lógó J., Modal Approximation Based Optimal Design of Dynamically Loaded Plastic Structures, Periodica Polytechnica Civil Engineering, ISSN: 0553-6626, DOI: 10.3311/PPci.11016, pp.1-6, 2017

Abstract:
The purpose of this study is to present an optimal design procedure for elasto-plastic structures subjected to impact loading. The proposed method is based on mode approximation of the displacement field and assumption of constant acceleration of impacted structure during whole time of deformation process until the plastic displacement limit is reached. Derivation of the method begins with the application of the principle of conservation of linear momentum, followed by determination of inertial forces. The final stage of the method utilizes an optimization technique in order to find a minimum weight structure. Eventually, effectiveness and usefulness of the proposed method is demonstrated on the example of a planar truss structure subjected to dynamic loading caused by a mass impacting the structure with a given initial velocity.

Keywords:
structural dynamics, optimal design, elasto-plastic structures, short-time dynamic loading

(15p.)
21.Byra M., Kruglenko E., Gambin B., Nowicki A., Temperature Monitoring during Focused Ultrasound Treatment by Means of the Homodyned K Distribution, ACTA PHYSICA POLONICA A, ISSN: 0587-4246, DOI: 10.12693/APhysPolA.131.1525, Vol.131, No.6, pp.1525-1528, 2017
Byra M., Kruglenko E., Gambin B., Nowicki A., Temperature Monitoring during Focused Ultrasound Treatment by Means of the Homodyned K Distribution, ACTA PHYSICA POLONICA A, ISSN: 0587-4246, DOI: 10.12693/APhysPolA.131.1525, Vol.131, No.6, pp.1525-1528, 2017

Abstract:
Temperature monitoring is essential for various medical treatments. In this work, we investigate the impact
of temperature on backscattered ultrasound echo statistics during a high intensity focused ultrasound treatment. A tissue mimicking phantom was heated with a spherical ultrasonic transducer up to 56 _C in order to imitate tissue necrosis. During the heating, an imaging scanner was used to acquire backscattered echoes from the heated region. These data was then modeled with the homodyned K distribution. We found that the best temperature indicator can be obtained by combining two parameters of the model, namely the backscattered echo mean intensity and the effective number of scatterers per resolution cell. Next, ultrasonic thermometer was designed and used to create a map of the temperature induced within the tissue phantom during the treatment

Keywords:
Temperature monitoring, homodyned K distribution, focused ultrasound

(15p.)
22.Proniewska K., Pręgowska A., Malinowski K.P., Sleep-related breathing biomarkers as a predictor of vital functions, Bio-Algorithms and Med-Systems, ISSN: 1895-9091, DOI: 10.1515/bams-2017-0003, Vol.13, No.1, pp.43-49, 2017
Proniewska K., Pręgowska A., Malinowski K.P., Sleep-related breathing biomarkers as a predictor of vital functions, Bio-Algorithms and Med-Systems, ISSN: 1895-9091, DOI: 10.1515/bams-2017-0003, Vol.13, No.1, pp.43-49, 2017

Abstract:
Because an average human spends one third of his life asleep, it is apparent that the quality of sleep has an important impact on the overall quality of life. To properly understand the influence of sleep, it is important to know how to detect its disorders such as snoring, wheezing, or sleep apnea. The aim of this study is to investigate the predictive capability of a dual-modality analysis scheme for methods of sleep-related breathing disorders (SRBDs) using biosignals captured during sleep. Two logistic regressions constructed using backward stepwise regression to minimize the Akaike information criterion were extensively considered. To evaluate classification correctness, receiver operating characteristic (ROC) curves were used. The proposed classification methodology was validated with constructed Random Forests methodology. Breathing sounds and electrocardiograms of 15 study subjects with different degrees of SRBD were captured and analyzed. Our results show that the proposed classification model based on selected parameters for both logistic regressions determine the different types of acoustic events during sleep. The ROC curve indicates that selected parameters can distinguish normal versus abnormal events during sleep with high sensitivity and specificity. The percentage of prediction for defined SRBDs is very high. The initial assumption was that the quality of result is growing with the number of parameters included in the model. The best recognition reached is more than 89% of good predictions. Thus, sleep monitoring of breath leads to the diagnosis of vital function disorders. The proposed methodology helps find a way of snoring rehabilitation, makes decisions concerning future treatment, and has an influence on the sleep quality.

Keywords:
patient monitoring, sleep-related breathing disorders, vital functions

(8p.)
23.Żurek Z.H., Kukla D., Jasiński T., Wykorzystanie mostka rlc do oceny postępu pełzania wysokotemperaturowego stali P91, ZESZYTY PROBLEMOWE - MASZYNY ELEKTRYCZNE, ISSN: 0239-3646, Vol.113, No.1, pp.215-219, 2017
Żurek Z.H., Kukla D., Jasiński T., Wykorzystanie mostka rlc do oceny postępu pełzania wysokotemperaturowego stali P91, ZESZYTY PROBLEMOWE - MASZYNY ELEKTRYCZNE, ISSN: 0239-3646, Vol.113, No.1, pp.215-219, 2017

Abstract:
W artykule przedstawiono możliwości oceny zmian parametrów fizycznych próbek ze stali P91 w oparciu o zmodyfikowane metody badań magneto-indukcyjnych. Badania przeprowadzono urządzeniami minimalizującymi koszty badań nie wpływającymi na dokładność. Zastosowano mostek pomiarowy RLC [8] i sondę pomiarową LDC1000 [9-11]. Przedstawione wstępne wyniki badań potwierdzają przyjęte założenia i wskazują na szeroki zakres zastosowań w przemyśle.

Keywords:
metody magneto indukcyjne, NDT, NDE

(7p.)
24.Pawłowska S., Nakielski P., Pierini F., Zembrzycki K., Piechocka I.K., Kowalewski T.A., Tumbling, rotating and coiling of nanofilaments in an oscillating microchannel flow, BioNano6, Biomolecules and Nanostructures 6, 2017-05-10/05-14, Podlesice (PL), No.41E, pp.60, 2017
25.Szmidt T., Konowrocki R., Flutter vibrations of pipe conveying air damped by electromagnetic devices of motional type, PTSK, 24th PTSK Scientific Workshop International Conference Simulation in Research and Development, 2017-05-24/05-27, Krynica (PL), pp.1-2, 2017
Szmidt T., Konowrocki R., Flutter vibrations of pipe conveying air damped by electromagnetic devices of motional type, PTSK, 24th PTSK Scientific Workshop International Conference Simulation in Research and Development, 2017-05-24/05-27, Krynica (PL), pp.1-2, 2017

Abstract:
The analysis of stability the pipe with electromagnetic coupling in active elements has been done. Application of electromagnetic actuators leads to an increase in the critical flow velocity.The frequency of self-excited vibrations can either change with the volt-age supplied depending on the position of the active elements.

Keywords:
Flutter vibrations, electromagnetic coupling, electromagnetic actuators, EM damper of motional type

26.Konowrocki R., An influence of electromechanical coupling effects on stability of the drive systems of HST driven by electric motors, PTSK, 24th PTSK Scientific Workshop International Conference Simulation in Research and Development, 2017-05-24/05-27, Krynica (PL), pp.15-16, 2017
Konowrocki R., An influence of electromechanical coupling effects on stability of the drive systems of HST driven by electric motors, PTSK, 24th PTSK Scientific Workshop International Conference Simulation in Research and Development, 2017-05-24/05-27, Krynica (PL), pp.15-16, 2017

Abstract:
The analysis of stability the High Speed Train traction drive with electromechanical coupling has been done. Using the energy balance of the natural modes of vibration for the model of the drive system leads to determining the influence of electromagnetic parameters on its stability in relation to self-excited vibrations induced by friction.

Keywords:
electromechanical coupling, high speed train, stability analizys, synchronous motor

27.Ortiz A.R., Błachowski B., Hołobut P., Franco J.M., Marulanda J., Thomson P., Modeling and Measurement of a Pedestrian’s Center-of-Mass Trajectory, 35th IMAC, XXXV International Modal Analysis Conference, A Conference and Exposition on Structural Dynamics 2017, 2017-01-30/02-02, Garden Grove, CA. (US), DOI: 10.1007/978-3-319-54777-0_20, pp.159-167, 2017
Ortiz A.R., Błachowski B., Hołobut P., Franco J.M., Marulanda J., Thomson P., Modeling and Measurement of a Pedestrian’s Center-of-Mass Trajectory, 35th IMAC, XXXV International Modal Analysis Conference, A Conference and Exposition on Structural Dynamics 2017, 2017-01-30/02-02, Garden Grove, CA. (US), DOI: 10.1007/978-3-319-54777-0_20, pp.159-167, 2017

Abstract:
This paper presents the measurement and model updating of a pedestrian’s center of mass trajectory. A mathematical model proposed by the authors is updated using the actual trajectory of a pedestrian. The mathematical model is based on the principle that a human’s control capability tries to maintain balance with respect to the pedestrian’s center of mass (CoM), independently of the surface type. In this research, the human is considered as a mass point concentrated at CoM. The parameters of the models are updated using experimental identification of the human walking trajectory on a rigid surface. The proposed measurement technique uses a depth sensor, which enable skeletal tracking of the pedestrian walking on rigid or flexible structures. Experiments were performed using a mobile platform with the time-of-flight commercial camera Microsoft Kinect for Windows 2.0. The velocity of the mobile platform is set to maintain a 1 m separation from the pedestrian in order to provide high resolution. The results of the measurement technique allowed the identification of the human’s CoM trajectory. The results of the model updating process present the probability density function of the parameters which could be used for modeling the CoM’s trajectory of the pedestrian.

Keywords:
Human-structure interaction, Pedestrian’s trajectory, Human-induced vibrations, MS Kinect sensor

28.Brodecki A., Szymczak T., Kowalewski Z., Digital image corellation technique as a tool for kinematics assessments of structural components, ISMMS, 9th International Symposium on Mechanics of Materials and Structures, 2017-06-04/06-08, Augustów (PL), pp.19-20, 2017
Brodecki A., Szymczak T., Kowalewski Z., Digital image corellation technique as a tool for kinematics assessments of structural components, ISMMS, 9th International Symposium on Mechanics of Materials and Structures, 2017-06-04/06-08, Augustów (PL), pp.19-20, 2017

Abstract:
The paper reports results of tests focused on determination of kinematic properties of components under cyclic loading. DIC system called 5M PONTOS was employed to follow variations of displacement and velocity versus time. It was conducted by a use of markers stuck on selected sections of components tested. Results are presented in 2D and 3D coordinate systems expressing behaviour of elements such as: car engine, boat frame and mechanical coupling device. These data enable to capture weak and strong sections of the component tested at various loading conditions.

Keywords:
digital image correlation system, cyclic loading, PONTOS, motion, displacement, 3D coordinate system

29.Urbanek O., Sajkiewicz P., Biomimetically surface modified fibres for cartilage regeneration, TERMIS European Chapter Meetin, European Chapter Meeting of the Tissue Engineering and Regenerative Medicine International Society 2017, 2017-06-26/06-30, Davos (CH), pp.P666, 2017
30.Nakielski P., Pierini F., Piechocka I.K., Blood clotting in the contact with nanofibers, NanoTech, NanoTech Poland International Conference & Exhibition, 2017-06-01/06-03, Poznań (PL), pp.178-178, 2017
Nakielski P., Pierini F., Piechocka I.K., Blood clotting in the contact with nanofibers, NanoTech, NanoTech Poland International Conference & Exhibition, 2017-06-01/06-03, Poznań (PL), pp.178-178, 2017

Abstract:
Nanofibers have received considerable attention in the past years, mainly due to their vast application in medicine [1]. One of the fastest growing areas of application are wound dressings and hemostats. Among the major causes of death from trauma, massive bleeding is responsible for 30 – 40% of mortality. In the hospital, massive bleeding are the second most common cause of death (22%) just after cardiac factors (33%) [2].
Despite a large number of experiments done in the topic of blood-biomaterial interactions, coagulation mechanisms are still not fully understood. Therefore, the main objective of our work is the analysis of protein adsorption, platelet adhesion and aggregation, and blood plasma coagulation in the contact with polymer nanofibers. Various synthetic polymers, their blends with natural polymers of confirmed hemostatic effect e.g. collagen and gelatine, and additionally nanofibers made of chitosan are investigated for their potential to stop bleeding. In the final, controlled release of drugs affecting coagulation cascade will be an important step providing accelerated blood clot formation.

31.Dulnik J., Kołbuk D., Denis P., Sajkiewicz P., Cellular studies of electrospun PCL/biocomponent nanofibers from alternative and traditional solvents, TERMIS European Chapter Meetin, European Chapter Meeting of the Tissue Engineering and Regenerative Medicine International Society 2017, 2017-06-26/06-30, Davos (CH), pp.P715, 2017
32.Chrzanowska-Giżyńska J., Hoffman J., Mościcki T., Comparison of tungsten borides layers deposited by laser pulse and magnetron sputtering, CNM, 5th Conference on Nano- and Micromechanics, 2017-07-04/07-06, Wrocław (PL), No.O-26, pp.92-93, 2017
Chrzanowska-Giżyńska J., Hoffman J., Mościcki T., Comparison of tungsten borides layers deposited by laser pulse and magnetron sputtering, CNM, 5th Conference on Nano- and Micromechanics, 2017-07-04/07-06, Wrocław (PL), No.O-26, pp.92-93, 2017

Keywords:
magnetron sputtering, pulsed laser deposition, superhard materials, tungsten borides

33.Sadowski P., Kowalczyk-Gajewska K., Stupkiewicz S., Micromechanical modelling of elasto-plastic composites: efficient and robust finite-element implementation of Mori-Tanaka model, CNM, 5th Conference on Nano- and Micromechanics, 2017-07-04/07-06, Wrocław (PL), No.O-08, pp.31-33, 2017
Sadowski P., Kowalczyk-Gajewska K., Stupkiewicz S., Micromechanical modelling of elasto-plastic composites: efficient and robust finite-element implementation of Mori-Tanaka model, CNM, 5th Conference on Nano- and Micromechanics, 2017-07-04/07-06, Wrocław (PL), No.O-08, pp.31-33, 2017

Keywords:
Mean-field homogenization, Mori-Tanaka method, Composite materials, Finite element method

34.Pawełek A., Ozgowicz W., Ranachowski Z., Kúdela S., Piątkowski A., Kúdela S.Jr., Ranachowski P., Behaviour of Acoustic Emission in Deformation and Microcracking Processes of Mg Alloys Matrix Composites Subjected to Compression Tests, ARCHIVES OF CURRENT RESEARCH INTERNATIONAL, ISSN: 2454-7077, DOI: 10.9734/ACRI/2017/34598, Vol.8, No.2, pp.1-13, 2017
Pawełek A., Ozgowicz W., Ranachowski Z., Kúdela S., Piątkowski A., Kúdela S.Jr., Ranachowski P., Behaviour of Acoustic Emission in Deformation and Microcracking Processes of Mg Alloys Matrix Composites Subjected to Compression Tests, ARCHIVES OF CURRENT RESEARCH INTERNATIONAL, ISSN: 2454-7077, DOI: 10.9734/ACRI/2017/34598, Vol.8, No.2, pp.1-13, 2017

Abstract:
Research results on both mechanical and acoustic emission (AE) behavior of Mg-Li and Mg-Al alloys matrix composites (AMC) reinforced with ceramic δ-Al2O3 or carbon fibers subjected to the channel-die compression at room and elevated temperatures are presented in this paper. The AE measurements at room temperature showed that, the effect of anisotropy of the fibres distribution (random planar distribution) with respect to the compression axis appeared in the most investigated composites, whereas the AE activity at 140°C revealed a two- range character and the rate of AE events at 140°C was higher than at room temperature. These effects are discussed in terms of both the differences in thermal expansion between the fibres and the matrix as well as the weakening of the coherency between the fibres and the matrix leading to stronger debonding effects at 140°C than at room temperature. The spectral analysis of AE signals was performed with the Windowed Fourier Transform method, which served to plot the spectral density of AE signal as a function of frequency. The alominous and corundum ceramics types were also investigated in order to illustrate the enhanced AE, which was related to the different crack paths in the final stages of the sample degradation. The results were also discussed on the basis of SEM images, including the in-situ observations of microcracking as well as the dislocation strain mechanisms and microcracking ones during the channel-die compression of the Mg-Li-Al AMC.

Keywords:
composites, fibres microcracking, acoustic emission, strain mechanisms, dislocations

35.Fantilli A.P., Jóźwiak-Niedźwiedzka D., Gibas K., Dulnik J., The compability between wool fibers and cementitious mortars, ICBBM & EcoGRAFI, Second International RILEM Conference on Bio-based Building Materials 1st Conference on ECOlogical valorisation of GRAnular and FIbrous materials, 2017-06-21/06-23, Clermont-Ferrand (FR), pp.42-47, 2017
Fantilli A.P., Jóźwiak-Niedźwiedzka D., Gibas K., Dulnik J., The compability between wool fibers and cementitious mortars, ICBBM & EcoGRAFI, Second International RILEM Conference on Bio-based Building Materials 1st Conference on ECOlogical valorisation of GRAnular and FIbrous materials, 2017-06-21/06-23, Clermont-Ferrand (FR), pp.42-47, 2017

Abstract:
The addition of natural fibers residue in cement based materials can be a sustainable technological alternative for traditional dispersed reinforcement, and can improve the performance of brittle matrix materials. The presence of a wool reinforcement can increase the fracture toughness and, at the same time, can reduce the environmental impact of cementitious mortars. The beneficial effects are similarly to those observed in presence of vegetal fibers (e.g., hemp), which have been largely investigated in the literature. However, there are some limits in the use of wool fibers due to their chemical compatibility with the cement matrix, as they can dissolve in alkaline environments. In the present paper, to investigate the compatibility between wool fibers and cementitious mortars, laboratory prototypes have been taken into consideration. Three series of wool-reinforced mortar beams have been cast and cured in water (20°C) or in dry conditions (temp. 20 °C, 50% R.H.) for some days. Portland-limestone cement CEM II has been used, whereas the content of fibers has been limited to about 1% in volume to maintain the workability of the mortars. To investigate the chemical compatibility, and the subsequent effects on the mechanical performances, prototypes have been tested in three point bending. After the mechanical test, the mortars microstructure was evaluated through SEM images and by thin section in transmitted light, in order to individuate a possible relationship between the dissolution of wool and curing conditions. The microstructure observation revealed the capability of wool fibers to bridge the cracks, and to reduce the brittleness of plain mortars. The differences in the mortars microstructure due to alternative curing conditions were also observed and described in the paper. Accordingly, wool could be effectively used to reduce the plastic shrinkage of cementbased composites, like the industrially manufactured polypropylene fibers.

Keywords:
Wool fibers, Plain cement-based mortar, Fiber-reinforced mortar, Polypropylene fibers, Three point bending tests, SEM analyses

36.Pieczyska E.A., Golasiński K., Staszczak M., Maj M., Furuta T., Kuramoto S., A thermomechanical analysis of high elasto-plastic properties of gum metal at various strain rates, M2D, 7th International Conference on Mechanics and Materials in Design, 2017-06-11/06-15, Albufeira (PT), No.7002, pp.131-132, 2017
Pieczyska E.A., Golasiński K., Staszczak M., Maj M., Furuta T., Kuramoto S., A thermomechanical analysis of high elasto-plastic properties of gum metal at various strain rates, M2D, 7th International Conference on Mechanics and Materials in Design, 2017-06-11/06-15, Albufeira (PT), No.7002, pp.131-132, 2017

Abstract:
Mechanical characteristics obtained by MTS testing machine and digital image correlation (DIC) algorithm as well as the related temperature changes in a new B-Ti alloy - Gum Metal, subjected to tension in a wide spectrum of the strain rates, are presented The fast and sensitive infrared camera ThermaCam Phoenix allowed estimating temperature changes accompanying the specimen deformation process in contactless manner. The obtained mechanical curves confirm an ultra-low elastic modulus and high strength of Gum Metal. Furthermore, it was presented how the stress-strain characteristics change from hardening to softening depending on the strain rate. The thermoelastic effect, estimated by the IR technique was discussed according to the Gum Metal yield point.

Keywords:
gum metal, titanium alloy, tension test, strain rate, thermomechanical coupling

37.Dunić V., Slavković R., Pieczyska E., Thermo-mechanical numerical analysis of transformation-induced stress relaxation during pseudoelastic behavior of SMA, , No.T.4.7, pp.28-1-28-6, 2017
Dunić V., Slavković R., Pieczyska E., Thermo-mechanical numerical analysis of transformation-induced stress relaxation during pseudoelastic behavior of SMA, , No.T.4.7, pp.28-1-28-6, 2017

Abstract:
A stress relaxation phenomenon is observed by coupled thermo-mechanical numerical analysis of SMA subjected to uniaxial test. The thermo-mechanical coupling is realized in the partitioned approach. The software components for the structural analysis (PAKS) and the heat transfer (PAKT) based on the Finite Element Method (FEM) have been used. The latent heat production is correlated with the amount of the martensitic volume fraction. The thermo-mechanical numerical analysis of a belt type specimen has been investigated for the strain controlled loading with the break during the martensitic transformation. The thermally induced martensitic transformation induced the significant stress change during the loading break what was expected according to the experimental results from literature.

Keywords:
shape memory alloys, stress relaxation, thermo-mechanical coupling, phase transformation, partitioned coupling

38.Gilewicz J., Pindor M., Telega J.J., Tokarzewski S., Continued fractions, two-point Padé approximants and errors in the Stieltjes case, JOURNAL OF COMPUTATIONAL AND APPLIED MATHEMATICS, ISSN: 0377-0427, DOI: 10.1016/S0377-0427(01)00538-6, Vol.145, No.1, pp.99-112, 2002
Gilewicz J., Pindor M., Telega J.J., Tokarzewski S., Continued fractions, two-point Padé approximants and errors in the Stieltjes case, JOURNAL OF COMPUTATIONAL AND APPLIED MATHEMATICS, ISSN: 0377-0427, DOI: 10.1016/S0377-0427(01)00538-6, Vol.145, No.1, pp.99-112, 2002

Abstract:
A Stieltjes function is expanded in mixed T- and S-continued fraction. The relations between approximants of this continued fraction and two-point Padé approximants are established. The method used by Gilewicz and Magnus (J. Comput. Appl. Math. 49 (1993) 79; Integral Transforms Special Functions 1 (1993) 9) has been adapted to obtain the exact relations between the errors of the contiguous two-point Padé approximants in the whole cut complex plane.

Keywords:
Two-point Padé approximation, Stieltjes functions

39.Banaszek J., Jaluria Y., Kowalewski T.A., Rebow M., Semi-implicit FEM analysis of natural convection in freezing water, Numerical Heat Transfer, Part A: Applications, ISSN: 1040-7782, Vol.36, No.5, pp.449-472, 1999
Banaszek J., Jaluria Y., Kowalewski T.A., Rebow M., Semi-implicit FEM analysis of natural convection in freezing water, Numerical Heat Transfer, Part A: Applications, ISSN: 1040-7782, Vol.36, No.5, pp.449-472, 1999

Abstract:
A semi-implicit finite element method (FEM) is presented for the two-dimensional computer simulation of solid-liquid phase change controlled by natural convection and conduction. The algorithm is based on a combination of (1) a projection method to uncouple velocity calculations from pressure calculations for incompressible fluid flow, (2) the backward Euler and explicit Adams-Bashforth schemes to effectively integrate diffusion and advection in time, and (3) an enthalpy-porosity approach to account for the latent heat effect on a fixed finite element grid. Credibility of the obtained numerical predictions is investigated through computational model verification and validation procedures. Commonly used benchmark problems are employed to verify the algorithm accuracy and performance. The natural convection of freezing pure water is studied experimentally through the use of sophisticated full-field acquisition experimental techniques. The measured velocity and temperature fields are compared with the pertinent calculations. The range of congruity of the experimental and numerical results is thoroughly studied, and potential reasons of some disparity in a local structure of the natural convection flow and in the interface shape are discussed.

40.Gelfgat A.Yu., Bar-Yoseph P.Z., Solan A., Kowalewski T.A., An axisymmetry-breaking instability of axially symmetric natural convection, INTERNATIONAL JOURNAL OF TRANSPORT PHENOMENA, ISSN: 1028-6578, Vol.1, No.3, pp.173-190, 1999
Gelfgat A.Yu., Bar-Yoseph P.Z., Solan A., Kowalewski T.A., An axisymmetry-breaking instability of axially symmetric natural convection, INTERNATIONAL JOURNAL OF TRANSPORT PHENOMENA, ISSN: 1028-6578, Vol.1, No.3, pp.173-190, 1999

Abstract:
The three-dimensional instability of an axisymmetric natural convection flow is investigated numericaUy using a global spectral Galerkin method. The linear stability problem separates for different azimuthal modes. This aUowsus to reduce the problem to a sequence of 2D-like problems. The formulation of the numerical approach and several test calculations are reported. The numerical results are successfully compared with an experiment on natural convection of water in a vertical cylinder, which shows an axisymmetry-breaking instability with a high azimuthal wavenumber.

Keywords:
Axisymmetry-breaking instability, natural convection, global Galerkin method

41.Kowalewski T.A., Rebow M., Freezing of water in the differentially heated cubic cavity, International Journal of Computational Fluid Dynamics, ISSN: 1061-8562, Vol.11, pp.193-210, 1999
Kowalewski T.A., Rebow M., Freezing of water in the differentially heated cubic cavity, International Journal of Computational Fluid Dynamics, ISSN: 1061-8562, Vol.11, pp.193-210, 1999

Abstract:
An experimental and numerical study has been made of transient natural convection of water freezing in a cube-shaped cavity. The effect of the heat transfer through the side walls is studied in two configurations: with the cavity surrounded by air and with the cavity immersed in an external water bath of constant temperature. The experimental data for the velocity and temperature fields are obtained using liquid crystal tracers. The transient development of the ice/water interface is measured. The collected data are used as an experimental benchmark and compared with numerical results obtained from a Finite-difference code with boundary fitted grid generation. The computational model has been adopted to simulate as closely as possible the physical experiment. Hence, fully variable fluid properties are implemented in the code, and, to improve modelling of the thermal boundary conditions, the energy equation is also solved inside the bounding walls. Although the general behaviour of the calculated ice front and its volume matches observations, several details of the flow structure do not. Observed discrepancies between experimental and numerical results indicate the necessity of verifying and improving the usual assumptions for modelling ice formation.

Keywords:
Natural convection, freezing, phase change, experimental benchmark, water density anomaly, liquid crystals, particle image velocimetry and thermometry, boundary fitted grid, finite differences vorticity-vector potential method

42.Quenot G.M., Pakleza J., Kowalewski T.A., Particle Image Velocimetry with Optical Flow, Experiments in Fluids, ISSN: 0723-4864, DOI: 10.1007/s003480050222, Vol.25, No.3, pp.177-189, 1998
Quenot G.M., Pakleza J., Kowalewski T.A., Particle Image Velocimetry with Optical Flow, Experiments in Fluids, ISSN: 0723-4864, DOI: 10.1007/s003480050222, Vol.25, No.3, pp.177-189, 1998

Abstract:
An optical Flow technique based on the use of Dynamic Programming has been applied to Particle Image Velocimetry thus yielding a significant increase in the accuracy and spatial resolution of the velocity field. Results are presented for calibrated synthetic sequences of images and for sequences of real images taken for a thermally driven flow of water with a freezing front. The accuracy remains better than 0.5 pixel/frame for tested two-image sequences and 0.2 pixel/frame for four-image sequences, even with a 10% added noise level and allowing 10% of particles of appear or disappear. A velocity vector is obtained for every pixel of the image.

43.Łodygowski T., Perzyna P., Numerical modelling of localized fracture of inelastic solids in dynamic loading processes, INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, ISSN: 0029-5981, DOI: 10.1002/(SICI)1097-0207(19971130)40:22<4137::AID-NME260>3.0., Vol.40, pp.4137-4158, 1997
Łodygowski T., Perzyna P., Numerical modelling of localized fracture of inelastic solids in dynamic loading processes, INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, ISSN: 0029-5981, DOI: 10.1002/(SICI)1097-0207(19971130)40:22<4137::AID-NME260>3.0., Vol.40, pp.4137-4158, 1997

Abstract:
The main objective of the paper is the investigation of adiabatic shear band localized fracture phenomenon in inelastic solids during dynamic loading processes. This kind of fracture can occur as a result of an adiabatic shear band localization generally attributed to a plastic instability implied by microdamage and thermal softening during dynamic plastic flow processes.

By applying ideas of synergetics it can be shown that as a result of instability hierarchies a system is self-organized into a new shear band pattern system. This leads to the conclusion that inelastic solid body considered during the dynamics process becomes a two-phase material system. Particular attention is focussed on attempt to construct a physically and experimentally justified localized fracture theory that relates the kinetics of material failure on the microstructural level to continuum mechanics. The description of the microstructural damage process is based on dynamic experiments with carefully controlled load amplitudes and duration. The microdamage process has been treated as a sequence of nucleation, growth and coalescence of microcracks. The microdamage kinetics interacts with thermal and load changes to make failure of solids a highly rate, temperature and history-dependent, non-linear process.

The theory of thermoviscoplasticity is developed within the framework of the rate-type covariance material structure with a finite set of internal state variables. The theory takes into consideration the effects of microdamage mechanism and thermomechanical coupling. The dynamic failure criterion within localized shear band region is proposed. The relaxation time is used as a regularization parameter. Rate dependency (viscosity) allows the spatial differential operator in the governing equations to retain its ellipticity, and the initial-value problem is well-posed. The viscoplastic regularization procedure assures the unconditionally stable integration algorithm by using the finite element method. Particular attention is focused on the well-posedness of the evolution problem (the initial–boundary value problem) as well as on its numerical solutions. Convergence, consistency and stability of the discretized problem are discussed. The Lax equivalence theorem is formulated and conditions under which this theorem is valid are examined.

Utilizing the finite element method and ABAQUS system for regularized elasto–viscoplastic model the numerical investigation of the three-dimensional dynamic adiabatic deformation in a particular body at nominal strain rates ranging over 103−104 s−1 is presented. A thin shear band region of finite width which undergoes significant deformation and temperature rise has been determined. Its evolution until occurrence of final fracture has been simulated. Numerical results are compared with available experimental observation data.

Keywords:
viscoplasticity, localization, regularization, micro-damage, localized fracture

44.Yarin A., Kowalewski T.A., Hiller W.J., Koch St., Distribution of particles suspended in convective flow in differentially heated cavity, PHYSICS OF FLUIDS, ISSN: 1070-6631, DOI: 10.1063/1.868913 , Vol.8, No.5, pp.1130-1140, 1996
Yarin A., Kowalewski T.A., Hiller W.J., Koch St., Distribution of particles suspended in convective flow in differentially heated cavity, PHYSICS OF FLUIDS, ISSN: 1070-6631, DOI: 10.1063/1.868913 , Vol.8, No.5, pp.1130-1140, 1996

Abstract:
Our aim is to explore, both experimentally and theoretically, the cumulative effects of small particle–liquid density difference, where the particles are used as tracers in recirculating flow. As an example we take a flow field generated in a differentially heated cavity. The main flow structure in such a cavity consists in one or two spiraling motions. Long‐term observations of such structures with the help of tracers (small particles) indicated that accumulation of the particles may set in at some flow regions. For theoretical insight into the phenomenon, a simple analytical model of recirculating (rotating) flow was studied. It was assumed that particles are spherical and rigid, and their presence does not affect the flow field. The particle Reynolds number is negligibly small, hence only the effects of particle–liquid density difference are of importance. Besides buoyancy, the effects of Saffman’s force and the inertial forces are also taken into account when calculating particle trajectories. Both cases were analyzed, particles with density slightly higher and lower than the fluid. It was found that in our case the inertial forces are egligible. In the numerical experiment trajectories of particles were investigated. The particles were allocated at random in the flow field obtained by numerical solution of the natural convection in the differentially heated cavity. In the experimental part, behavior of a dilute particle suspension in the convective cell was explored. In the model‐analytical study of a simple spiraling motion, it was found that due to the interaction of the recirculating convective flow field and the gravity‐buoyancy force, the particles may be trapped in some flow regions, whereas the rest of the flow field becomes particle‐free. This prediction agrees fairly well with the numerical and experimental findings.

45.Kowalewski T.A., On the separation of droplets from a liquid jet, Fluid Dynamics Research, ISSN: 0169-5983, DOI: 10.1016/0169-5983(95)00028-3, Vol.17, No.3, pp.121-145, 1996
Kowalewski T.A., On the separation of droplets from a liquid jet, Fluid Dynamics Research, ISSN: 0169-5983, DOI: 10.1016/0169-5983(95)00028-3, Vol.17, No.3, pp.121-145, 1996

Abstract:
The droplet separation from a liquid jet was investigated experimentally. Details of the shape of the thin liquid neck joining the droplet to its parent body were studied in terms of the fluid viscosity and the jet diameter. As the viscosity increased, the neck rapidly elongated creating a long thread. Its final diameter before rupture was approximately one micrometer and seems to be constant within wide range of parameters varied. One or multiple breakups of the micro-thread were observed, which produced micro-satellites, i.e. droplets in a micrometer range. The experimental results only partly confirmed the predictions of Eggers' (Phys. Rev. Lett. 71 (1993) 3458) similarity solution. The predicted shape of the pinch-off region well overlaps the long thread observed for very viscous liquids. However, the final jet diameter, retraction velocity of the thread and presence of multiple breakups differentiate the experimental evidence from the model expectations.

46.Becker E., Hiller W.J., Kowalewski T.A., Nonlinear dynamics of viscous droplets, JOURNAL OF FLUID MECHANICS, ISSN: 0022-1120, DOI: 10.1017/S0022112094003290, Vol.258, pp.191-216, 1994
Becker E., Hiller W.J., Kowalewski T.A., Nonlinear dynamics of viscous droplets, JOURNAL OF FLUID MECHANICS, ISSN: 0022-1120, DOI: 10.1017/S0022112094003290, Vol.258, pp.191-216, 1994

Abstract:
Nonlinear viscous droplet oscillations are analysed by solving the Navier-Stokes equation for an incompressible fluid. The method is based on mode expansions with modified solutions of the corresponding linear problem. A system of ordinary differential equations, including all nonlinear and viscous terms, is obtained by an extended application of the variational principle of Gauss to the underlying hydrodynamic equations. Results presented are in a very good agreement with experimental data up to oscillation amplitudes of 80% of the unperturbed droplet radius. Large-amplitude oscillations are also in a good agreement with the predictions of Lundgren & Mansour (boundary integral method) and Basaran (Galerkin-finite element method). The results show that viscosity has a large effect on mode coupling phenomena and that, in contradiction to the linear approach, the resonant mode interactions remain for asymptotically diminishing amplitudes of the fundamental mode.

47.Kowalewski T.A., Hiller W.J., Behnia M., An experimental study of evaporating small diameter jets, PHYSICS OF FLUIDS, ISSN: 1070-6631, DOI: 10.1063/1.858814, Vol.5, No.8, pp.1883-1890, 1993
Kowalewski T.A., Hiller W.J., Behnia M., An experimental study of evaporating small diameter jets, PHYSICS OF FLUIDS, ISSN: 1070-6631, DOI: 10.1063/1.858814, Vol.5, No.8, pp.1883-1890, 1993

Abstract:
The behavior of evaporating small diameter jets in a low‐pressure environment is studied experimentally. Charged coupled device (CCD) cameras connected to a computerized data logging system are employed for high‐speed imaging. Experiments at different jet velocities and environmental pressures have been performed with pure ether and ethanol, and also the mixtures of the two. Complex instability structures during the evaporation of the jet were observed. The recorded experimental evidences of these structures are presented and discussed.

48.Hiller W.J., Koch St., Kowalewski T.A., Stella F., Onset of natural convection in a cube, INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER, ISSN: 0017-9310, DOI: 10.1016/0017-9310(93)90008-T, Vol.36, No.13, pp.3251-3263, 1993
Hiller W.J., Koch St., Kowalewski T.A., Stella F., Onset of natural convection in a cube, INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER, ISSN: 0017-9310, DOI: 10.1016/0017-9310(93)90008-T, Vol.36, No.13, pp.3251-3263, 1993

Abstract:
The problem of transient natural convection in a cube-shaped cavity is investigated experimentally and numerically. The motion is driven by a sudden temperature difference applied to two opposite side walls of the vessel. The experiments are performed at a Rayleigh number of 1.66 × 105 and a Prandtl number of 1109, inside a 5 × 5 × 5 cm3 cavity made of Plexiglas, with two isothermal copper walls kept at a prescribed temperature. Numerical simulation has been performed using a finite difference vorticity-velocity model of the Navier-Stokes equation with the Boussinseq approximation. The theoretical predictions are found to be in good agreement with the experimental results.

49.Stückrad B., Hiller W.J., Kowalewski T.A., Measurement of dynamic surface tension by the oscillating droplet method, Experiments in Fluids, ISSN: 0723-4864, DOI: 10.1007/BF00223411, Vol.15, No.4, pp.332-340, 1993
Stückrad B., Hiller W.J., Kowalewski T.A., Measurement of dynamic surface tension by the oscillating droplet method, Experiments in Fluids, ISSN: 0723-4864, DOI: 10.1007/BF00223411, Vol.15, No.4, pp.332-340, 1993

Abstract:
An optical measuring method has been applied to determine the dynamic surface tension of aqueous solutions of heptanol. The method uses the frequency of an oscillating liquid droplet as an indicator of the surface tension of the liquid. Droplets with diameters in the range between 100 and 200 μm are produced by the controlled break-up of a liquid jet. The temporal development of the dynamic surface tension of heptanol-water solutions is interpreted by a diffusion controlled adsorption mechanism, based on the “three-layer” model of Ward and Tordai. Measured values of the surface tension of bi-distilled water, and the pure dynamic and static (asymptotic) surface tensions of the surfactant solutions are in very good agreement with values obtained by classical methods.

50.Becker E., Hiller W.J., Kowalewski T.A., Experimental and theoretical investigations of large amplitude oscillations of liquid droplets, JOURNAL OF FLUID MECHANICS, ISSN: 0022-1120, DOI: 10.1017/S0022112091003361, Vol.231, pp.189-210, 1991
Becker E., Hiller W.J., Kowalewski T.A., Experimental and theoretical investigations of large amplitude oscillations of liquid droplets, JOURNAL OF FLUID MECHANICS, ISSN: 0022-1120, DOI: 10.1017/S0022112091003361, Vol.231, pp.189-210, 1991

Abstract:
Finite-amplitude, axially symmetric oscillations of small (0.2 mm) liquid droplets in a gaseous environment are studied, both experimentally and theoretically. When the amplitude of natural oscillations of the fundamental mode exceeds approximately 10% of the droplet radius, typical nonlinear effects like the dependence of the oscillation frequency on the amplitude, the asymmetry of the oscillation amplitude, and the interaction between modes are observed. As the amplitude decreases due to viscous damping, the oscillation frequency and the amplitude decay factor reach their asymptotical values predicted by linear theory. The initial behaviour of the droplet is described quite satisfactorily by a proposed nonlinear inviscid theoretical model.

51.Hiller W.J., Kowalewski T.A., Surface tension measurements by the oscillating droplet method, Physicochemical Hydrodynamics, ISSN: 0191-9059, Vol.11, No.1, pp.103-112, 1989
52.Hiller W.J., Kowalewski T.A., Koch S., Three-dimensional structures in laminar natural convection in a cubic enclosure, Experimental Thermal and Fluid Science, ISSN: 0894-1777, DOI: 10.1016/0894-1777(89)90047-2, Vol.2, No.1, pp.34-44, 1989
Hiller W.J., Kowalewski T.A., Koch S., Three-dimensional structures in laminar natural convection in a cubic enclosure, Experimental Thermal and Fluid Science, ISSN: 0894-1777, DOI: 10.1016/0894-1777(89)90047-2, Vol.2, No.1, pp.34-44, 1989

Abstract:
The thermal convection in a cubic cavity, with two opposite vertical walls kept at prescribed temperatures, is investigated experimentally. The Rayleigh numbers ranged from 104 to 2 × 107 and the Prandtl numbers from 5.8 to 6 × 103. The velocity and vorticity fields are shown. The temperature fields were visualized with the help of liquid crystals suspended as small tracer particles in the medium. It is observed that convection in the cavity is strongly three-dimensional. The streamlines spiral from the foci on the walls toward the foci in the vertical midplane and vice versa. The disappearance of one of the vortices midway between the center and the front or back wall is observed for RA > 6 × 104. The topological structures are discussed. The experimental observations are compared with numerical calculations found in the literature.

Keywords:
natural convection, rectangular enclosures

53.Hiller W., Kowalewski T.A., An experimental study of the lateral migration of a droplet in a creeping flow , Experiments in Fluids, ISSN: 0723-4864, DOI: 10.1007/BF00272424, Vol.5, No.1, pp.43-48, 1986
Hiller W., Kowalewski T.A., An experimental study of the lateral migration of a droplet in a creeping flow , Experiments in Fluids, ISSN: 0723-4864, DOI: 10.1007/BF00272424, Vol.5, No.1, pp.43-48, 1986

Abstract:
The distribution of droplets in a plane Hagen-Poiseuille flow of dilute suspensions has been measured by a special LDA technique. This method assumes a well defined relation between the velocity of the droplets and their lateral position in the channel. The measurements have shown that the droplet distribution is non-uniform and depends on the viscosity ratio between the droplets and the carrier liquid. The results have been compared with a theory by Chan and Leal describing the lateral migration of suspended droplets.

54.Kowalewski T.A., Concentration and velocity measurements in the flow of droplet suspensions through a tube, Experiments in Fluids, ISSN: 0723-4864, DOI: 10.1007/BF00571868, Vol.2, No.4, pp.213-219, 1984
Kowalewski T.A., Concentration and velocity measurements in the flow of droplet suspensions through a tube, Experiments in Fluids, ISSN: 0723-4864, DOI: 10.1007/BF00571868, Vol.2, No.4, pp.213-219, 1984

Abstract:
Two optical methods, light absorption and LDA, are applied to measure the concentration and velocity profiles of droplet suspensions flowing through a tube. The droplet concentration is non-uniform and has two maxima, one near the tube wall and one on the tube axis. The measured velocity profiles are blunted, but a central plug-flow region is not observed. The concentration of droplets on the tube axis and the degree of velocity profile blunting depend on relative viscosity. These results can be qualitatively compared with the theory of Chan and Leal.

55.Kowalewski T.A., Velocity profiles of suspension flowing through a tube, ARCHIVES OF MECHANICS, ISSN: 0373-2029, Vol.32, No.6, pp.857-865, 1980
56.Olszak W., Perzyna P., On elastic/visco-plastic soils, IUTAM Symposia, Rheology and Soil Mechanics / Rhéologie et Mécanique des Sols, 1964-04-01/04-08, Grenoble (FR), pp.47-57, 1966