1. | Banach Z., Larecki W., Entropy-based mixed three-moment description of fermionic radiation transport in slab and spherical geometries, Kinetic and Related Models, ISSN: 1937-5093, DOI: 10.3934/krm.2017035, Vol.10, No.4, pp.879-900, 2017Banach Z., Larecki W., Entropy-based mixed three-moment description of fermionic radiation transport in slab and spherical geometries, Kinetic and Related Models, ISSN: 1937-5093, DOI: 10.3934/krm.2017035, Vol.10, No.4, pp.879-900, 2017Abstract: The mixed three-moment hydrodynamic description of fermionic radiation transport based on the Boltzmann entropy optimization procedure is considered for the case of one-dimensional flows. The conditions for realizability of the mixed three moments chosen as the energy density and two partial heat fluxes are established. The domain of admissible values of those moments is determined and the existence of the solution to the optimization problem is proved. Here, the standard approaches related to either the truncated Hausdorff or Markov moment problems do not apply because the non-negative fermionic distribution function, denoted f, must satisfy the inequality f _ 1 and, at the same time, there are three different intervals of integration in the integral formulae defining the mixed moments. The hydrodynamic equations are obtained in the form of the symmetric hyperbolic system for the Lagrange multipliers of the optimization problem with constraints. The potentials generating this system are explicitly determined as dilogarithm and trilogarithm functions of the Lagrange multipliers. The invertibility of the relation between moments and Lagrange multipliers is proved. However, the inverse relations cannot be determined in a closed analytic form. Using the H-theorem for the radiative transfer equation, it is shown that the derived system of hydrodynamic radiation equations has as a consequence an additional balance law with a non-negative source term. Keywords: Fermionic radiation, mixed moments, moment realizability domain, entropy optimization problem, symmetric hyperbolicity | |
2. | Jarząbek D.M., Milczarek M., Wojciechowski T., Dziekoński C., Chmielewski M., The effect of metal coatings on the interfacial bonding strength of ceramics to copper in sintered Cu-SiC composites, CERAMICS INTERNATIONAL, ISSN: 0272-8842, DOI: 10.1016/j.ceramint.2017.01.056, pp.1-9, 2017Jarząbek D.M., Milczarek M., Wojciechowski T., Dziekoński C., Chmielewski M., The effect of metal coatings on the interfacial bonding strength of ceramics to copper in sintered Cu-SiC composites, CERAMICS INTERNATIONAL, ISSN: 0272-8842, DOI: 10.1016/j.ceramint.2017.01.056, pp.1-9, 2017Abstract: Cu-SiC composites are very promising materials which have high thermal and electrical conductivity and may find many applications. Unfortunately, the main disadvantage of these materials is the dissolution of silicon in copper at elevated temperature, which significantly reduces their properties. In order to overcome this problem particles can be coated with a protective material before sintering. In this paper– the influence of three different metallic coatings on bonding strength were investigated. SiC particles were coated with tungsten, chromium or titanium. As reference a material with uncoated particles was prepared. The experiments were carried out with the use of microtensile tester. The highest increase in strength was observed in the case of chromium coating. On the other hand, the titanium coating, which was of very poor quality, decrease the bonding strength in comparison with uncoated particles. Furthermore, scanning electron and optical microscopes were used to determine the mechanism of debonding. Keywords: Interfacial bonding strength, Metal matrix composites, Tensile strength, Silicon carbide particles | |
3. | Kiełczyński P., Szalewski M., Balcerzak A., Wieja K., Rostocki A., Ptasznik S., Evaluation of High-Pressure Thermophysical Parameters of the Diacylglycerol (DAG) Oil Using Ultrasonic Waves, Food and Bioprocess Technology, ISSN: 1935-5130, DOI: 10.1007/s11947-016-1827-6, Vol.10, No.2, pp.358-369, 2017Kiełczyński P., Szalewski M., Balcerzak A., Wieja K., Rostocki A., Ptasznik S., Evaluation of High-Pressure Thermophysical Parameters of the Diacylglycerol (DAG) Oil Using Ultrasonic Waves, Food and Bioprocess Technology, ISSN: 1935-5130, DOI: 10.1007/s11947-016-1827-6, Vol.10, No.2, pp.358-369, 2017Abstract: Modeling of high-pressure technological processes in the food industry requires knowledge of thermophysical parameters of processed foodstuffs in a broad range of pressures and temperatures. However, the high-pressure thermophysical parameters of foodstuffs are very rarely published in the literature. Therefore, further research is necessary to achieve a deeper insight into the biophysical and thermophysical phenomena under pressure to provide better control of technological processes and optimize the effects of pressure. The essential goal of this work is to evaluate the impact of high pressure and temperature on the thermophysical parameters of liquid foodstuffs on the example of diacylglycerol (DAG) oil (which attracted recently a considerable attention from research and industrial communities due to its remarkable benefits for health), using ultrasonic wave velocity and density measurements. Isotherms of adiabatic and isothermal compressibility, isobaric thermal expansion coefficient, internal pressure, and thermal pressure coefficient versus pressure were evaluated, based on the measurement of the compressional ultrasonic wave velocity and density of DAG oil at high pressures (up to 500 MPa) and at various temperatures. The adiabatic compressibility is affected mostly by the changes of pressure, i.e., it grows about four times when the pressure increases from the atmospheric pressure (0.1 MPa) to 400 MPa at a temperature of 50 °C. By contrast, the internal pressure is a pronounced function of the temperature, i.e., it increases six times when the temperature rises from 20 to 50 °C at a pressure of a 200 MPa. To perform numerical calculations, it was convenient to introduce a Tammann–Tait type equation of state to approximate the measured density isotherms of the investigated DAG oil. The results obtained in this paper can be applied in modeling and optimization of high-pressure technological processes and processing of foodstuffs. Evaluation of high-pressure isotherms of the considered thermophysical parameters of the DAG oil is an original authors’ contribution to the state-of-the-art. Keywords: High-pressure food processing, Diacylglycerols, Thermophysical parameters, Isothermal compressibility, Isobaric thermal expansion coefficient, Ultrasonic methods | |
4. | Sławianowski J.J., Kovalchuk V., Gołubowska B., Martens A., Rożko E.E., Mechanics of affine bodies. Towards affine dynamical symmetry, JOURNAL OF MATHEMATICAL ANALYSIS AND APPLICATIONS, ISSN: 0022-247X, DOI: 10.1016/j.jmaa.2016.08.042, Vol.446, pp.493-520, 2017Sławianowski J.J., Kovalchuk V., Gołubowska B., Martens A., Rożko E.E., Mechanics of affine bodies. Towards affine dynamical symmetry, JOURNAL OF MATHEMATICAL ANALYSIS AND APPLICATIONS, ISSN: 0022-247X, DOI: 10.1016/j.jmaa.2016.08.042, Vol.446, pp.493-520, 2017Abstract: In this paper we discuss certain dynamical models of affine bodies, including problems of partial separability and integrability. There are some reasons to expect that the suggested models are dynamically viable and that on the fundamental level of physical phenomena the “large” affine symmetry of dynamical laws is more justified and desirable than the restricted invariance under isometries. Keywords: Homogeneous deformation, structured media, affinely-invariant dynamics, elastic vibrations encoded in kinetic energy, Calogero-Moser and Sutherland integrable lattices | |
5. | Ignaczak J., Domański W., An asymptotic approach to one-dimensional model of nonlinear thermoelasticity at low temperatures and small strains, JOURNAL OF THERMAL STRESSES, ISSN: 0149-5739, DOI: 10.1080/01495739.2016.1276872, pp.1-10, 2017Ignaczak J., Domański W., An asymptotic approach to one-dimensional model of nonlinear thermoelasticity at low temperatures and small strains, JOURNAL OF THERMAL STRESSES, ISSN: 0149-5739, DOI: 10.1080/01495739.2016.1276872, pp.1-10, 2017Abstract: A one-dimensional nonlinear homogeneous isotropic thermoelastic model with an elastic heat flow at low temperatures and small strains is analyzed using the method of weakly nonlinear asymptotics. For such a model, both the free energy and the heat flux vector depend not only on the absolute temperature and strain tensor but also on an elastic heat flow that satisfies an evolution equation. The governing equations are reduced to a matrix partial differential equations, and the associated Cauchy problem with a weakly perturbed initial condition is solved. The solution is given in the form of a power series with respect to a small parameter, the coeﬃcients of which are functions of a slow variable that satisfy a system of nonlinear second-order ordinary differential transport equations. A family of closed-form solutions to the transport equations is obtained. For a particular Cauchy problem in which the initial data are generated by a closed-form solution to the transport equations, the asymptotic solution in the form of a sum of four traveling thermoelastic waves admitting blow-up amplitudes is presented. Keywords: Low temperatures, nonlinear thermoelasticity, small strains, weakly nonlinear asymptotics | |
6. | Nowak Z., Nowak M., Pęcherski R., Potoczek M., Śliwa R.E., Numerical Simulations of Mechanical Properties of Alumina Foams Based on Computed Tomography, JOURNAL OF MECHANICS OF MATERIALS AND STRUCTURES, ISSN: 1559-3959, DOI: 10.2140/jomms.2017.12.107, Vol.12, No.1, pp.107-121, 2017Nowak Z., Nowak M., Pęcherski R., Potoczek M., Śliwa R.E., Numerical Simulations of Mechanical Properties of Alumina Foams Based on Computed Tomography, JOURNAL OF MECHANICS OF MATERIALS AND STRUCTURES, ISSN: 1559-3959, DOI: 10.2140/jomms.2017.12.107, Vol.12, No.1, pp.107-121, 2017Abstract: The aim of this paper is to apply the results of microtomography of alumina foam to create a numerical model and perform numerical simulations of compression tests. The geometric characteristics of real foam samples are estimated from tomographic and scanning electron microscopy images. The performance of the reconstructed models is compared to experimental values of elastic moduli. A preliminary analysis of failure strength simulations under compression of alumina foam is also provided. Keywords: Alumina open-cell foam, computed tomography microstructure, Young’s modulus, compressive strength of alumina foams | |