Study of melting of a pure gallium under influence of magnetic field in a square cavity with a local heat source

Numerical analysis of the unsteady natural convection with phase transitions inside the pure galluim under the influence of a uniform magnetic field with a heat source of constant temperature has been conducted in the presence of magnetic field. The vertical walls of the cavity are kept at low constant temperatures whereas the top and bottom horizontal walls are adiabatic with the exception of the heat source of high constant temperature. The mathematical model formulated in dimensionless stream function, vorticity and temperature variables is solved using the implicit finite difference schemes of the second order. The governing parameters are the Rayleigh and Hartmann numbers, and the dimensionless time. The effects of these parameters on the streamlines and isotherms are analyzed

Numerical simulation of natural convection melting in 2D and 3D enclosures

Natural convection melting in 2D and 3D enclosures with a local heater is studied numerically. The present research is related to a development of effective cooling system for the electronic devices using the phase change material that is essentially important nowadays. The domain of interest includes vertical cold walls, adiabatic horizontal walls and a discrete heater of constant high temperature located on the bottom adiabatic wall. The cavity is filled with a phase change material (PCM) in solid state at the beginning of the process. During the heating from the heat source PCM is melting. Numerical solution of the present problem has been conducted using the dimensionless transformed variables such as stream function and vorticity for 2D cavity and vector potential functions and vorticity vector for 3D cavity with appropriate initial and boundary conditions. The developed numerical technique has been verified comprehensively. Obtained results have shown a potential of the used methods for 2D and 3D problems. It has been found that, melting process is more intensive in 3D case and the heat transfer rate at the heater is greater for 2D in comparison with 3D data

Effect of nano-sized heat transfer enhancers on PCM-based heat sink performance at various heat loads

Many passive heat controlling technologies are based on the use of phase change materials

Natural convection melting influence on the thermal resistance of a brick partially filled with phase change material

The constant growth of urban agglomerations with the development of transport networks requires the optimal use of energy and new ways of storing it. Energy efficiency is becoming one of the main challenges of modern engineering. The use of phase change materials in construction expands the possibilities of accumulating and storing solar energy, as well as reducing energy consumption. In this study, we consider the problem of the effect of natural convection on heat transfer in a building block containing a phase change material. Heat transfer, taking into account melting in brick, was analyzed at various temperature differences. The mathematical model was formulated in the form of time-dependent equations of conjugate natural convection using non-dimensional stream function, vorticity, and temperature. The equations describing melting, taking into account natural convection, were solved using the finite difference method. Smoothing parameters were used to describe phase transitions in the material. As a result of calculations, local characteristics of heat and mass transfer at various points in time were obtained, as well as changes in temperature profiles on the side surfaces. It is shown that with a large volume of melt, natural convection increases heat loss by more than 10%

Tensile behavior of an austenitic stainless steel subjected to multidirectional forging

The mechanical behavior of a chromium -nickel austenitic stainless steel with submicrocrystalline structures produced by multidirectional forging (MDF) to a total strain of ∼ 4 at temperatures of 700 and 600° C was studied. This processing resulted in the formation of uniform ultrafine grained structure with an average crystallite size of 360 and 300 nm, respectively, and high dislocation density. The tensile tests were carried out in a wide temperature range 20 -650° C. At ambient temperature, the yield stress (YS) comprised 900 MPa and 730 MPa in the samples subjected to MDF at 600 and 700° C, respectively. It should be noted that this strength was achieved along with elongations of 16% and 22% in the samples subjected to MDF at 600 and 700° C. The YS decreased and elongati on-to-failure tends to increase with increasing test temperature and approaching 235 MPa and 51%, respectively, at 650° C. Effect of temperature on mechanical behavior of stainless steel with submicrocrystalline structure is discusse

Are the Mechanisms for Assessing the Quality of Training for Graduates of the Russian Penitentiary System Perfect?

The relevance of the study is due to the need to assess the quality of training of graduates of the Russian penitentiary system and the lack of an effective tool to assess the quality and level of training of graduates who have mastered professional educational programs at educational institutions of the Federal Penitentiary Service of Russia. In this regard, this article is aimed at identifying or disclosing mechanisms for evaluating the quality of educational services by independent experts, representatives of the employer, through professional and public accreditation of educational programs in educational institutions of the Federal Penitentiary Service of Russia. The leading methods to the study of this problem are general scientific methods (analysis, synthesis, analogy, generalization, etc.), which to introduce allow a comprehensive review of the procedure for professional and public accreditation of educational programs in the system of the Russian Federation. The article reveals the expected results of introducing the institution of professional public accreditation of educational programs in the Russian penitentiary system: improving the quality of the implemented educational programs, the level of organization of staff training, the quality and relevance of educational services, and the image of departmental services. The materials of the article are of practical value for improving the evaluation system of professional educational programs implemented in educational institutions of the Federal Penitentiary Service of Russia

Are the Mechanisms for Assessing the Quality of Training for Graduates of the Russian Penitentiary System Perfect?

The relevance of the study is due to the need to assess the quality of training of graduates of the Russian penitentiary system and the lack of an effective tool to assess the quality and level of training of graduates who have mastered professional educational programs at educational institutions of the Federal Penitentiary Service of Russia. In this regard, this article is aimed at identifying or disclosing mechanisms for evaluating the quality of educational services by independent experts, representatives of the employer, through professional and public accreditation of educational programs in educational institutions of the Federal Penitentiary Service of Russia. The leading methods to the study of this problem are general scientific methods (analysis, synthesis, analogy, generalization, etc.), which to introduce allow a comprehensive review of the procedure for professional and public accreditation of educational programs in the system of the Russian Federation. The article reveals the expected results of introducing the institution of professional public accreditation of educational programs in the Russian penitentiary system: improving the quality of the implemented educational programs, the level of organization of staff training, the quality and relevance of educational services, and the image of departmental services. The materials of the article are of practical value for improving the evaluation system of professional educational programs implemented in educational institutions of the Federal Penitentiary Service of Russia

Are the Mechanisms for Assessing the Quality of Training for Graduates of the Russian Penitentiary System Perfect?

The relevance of the study is due to the need to assess the quality of training of graduates of the Russian penitentiary system and the lack of an effective tool to assess the quality and level of training of graduates who have mastered professional educational programs at educational institutions of the Federal Penitentiary Service of Russia. In this regard, this article is aimed at identifying or disclosing mechanisms for evaluating the quality of educational services by independent experts, representatives of the employer, through professional and public accreditation of educational programs in educational institutions of the Federal Penitentiary Service of Russia. The leading methods to the study of this problem are general scientific methods (analysis, synthesis, analogy, generalization, etc.), which to introduce allow a comprehensive review of the procedure for professional and public accreditation of educational programs in the system of the Russian Federation. The article reveals the expected results of introducing the institution of professional public accreditation of educational programs in the Russian penitentiary system: improving the quality of the implemented educational programs, the level of organization of staff training, the quality and relevance of educational services, and the image of departmental services. The materials of the article are of practical value for improving the evaluation system of professional educational programs implemented in educational institutions of the Federal Penitentiary Service of Russia

Proactive monitoring system for investment projects: mathematical support

Using mathematical based evaluation systems will help ranking investment projects to select the best and most promising among the available. Based on the study, the author sees it best to apply mathematical models and concentrate on conceptual investment projects for reducing monitoring and evaluation costs, as well as initial development costs. Optimal ways to form expert groups for investment project proactive monitoring is offered in conclusio