# thermal conductivity

## MATHEMATICAL SPATIAL MODELS OF DETERMINATION OF TEMPERATURE FIELD FROM LOCALLY CONCENTRATED THERMAL HEATING

Linear and nonlinear mathematical models for determining the temperature field, and later the analysis of temperature regimes in isotropic spatial inhomogeneous media exposed to internal and external thermal loads have been developed. To do this, the thermal conductivity for such structures is described as a whole using symmetric unit functions, which allows us to consider boundary thermal conductivity problems with one linear and nonlinear differential equation of thermal conductivity with discontinuous coefficients and linear and nonlinear boundary conditions on boundary surfaces.

## Temperature modes in a heat-sensitive plate with local heating

Nonlinear mathematical models for the analysis of temperature regimes in a thermosensitive isotropic plate heated by locally concentrated heat sources have been developed. For this purpose, the heat-active zones of the plate are described using the theory of generalized functions. Given this, the equation of thermal conductivity and boundary conditions contain discontinuous and singular right parts. The original nonlinear equations of thermal conductivity and nonlinear boundary conditions are linearized by Kirchhoff transformation.

## Prediction of Thermophysical Characteristics of Fuel Rods Based on Calculations

The paper analyzes operating conditions, thermophysical characteristics were calculated as applied to WWER-1000 fuel rods in a four-year cycle for unified core. The paper gives a summary of models for calculating gas release, pressure of gases within fuel rod cladding, fuel swelling and thermal conductivity, fuel-cladding gap conductance. The thermophysical condition of fuels in a reactor core is one of the main factors that determine their serviceability.

## MATHEMATICAL MODEL OF HEAT EXCHANGE IN ELEMENTS OF DIGITAL DEVICES

A mathematical model of heat exchange analysis between an isotropic two-layer plate heated ba point heat source concentrated on the conjugation surfaces of layers and the environment has been developed.

## Analysis of the Possibility of the Polymeric Aggregates Use in the Design of Building Block

Particulate composite was prepared from a mixture of cement, gravel and water with additions of a polyepoxide and/or expanded polystyrene in powder. For consolidation, each mixture was poured into a mold, remaining for a short period and then removed. For complete solidification the specimens were cured with water during the final stage. The weight, compressive strength and thermal conductivity of the composite were determined.

## MATHEMATICAL MODELS OF HEAT TRANSFER IN ELEMENTS OF TURBOGENERATORS

Se­pa­ra­te mat­he­ma­ti­cal mo­dels for de­ter­mi­ning the tem­pe­ra­tu­re distri­bu­ti­on in the ele­ments of tur­bo­ge­ne­ra­tors ha­ve be­en de­ve­lo­ped, which are descri­bed ge­omet­ri­cally by an isot­ro­pic half-spa­ce and a he­at-sen­si­ti­ve spa­ce with lo­cally con­centra­ted so­ur­ces of he­ating. For this pur­po­se, using the the­ory of ge­ne­ra­li­zed functi­ons in a con­ve­ni­ent form, we wri­te the ini­ti­al dif­fe­ren­ti­al eq­ua­ti­ons of ther­mal con­duc­ti­vity with bo­un­dary con­di­ti­ons.

## NON-AUTOCLAVED HEAT INSULATING AERATED CONCRETE BASED ON COMPOSITE BINDER

One of the leaders of wall materials in the modern market, which combines high constructional and thermal insulation properties, is cellular concrete, in particular non-autoclave hardening. Improving efficiency of cellular concrete as a heat insulating material is, above all, in the maximum possible decrease in average density, while providing a certain level of physical and mechanical indicators necessary for the manufacture of products in the form of slabs.

## USING IMPROVED DESIGN METHOD OF SHEER STRENGTH OF REINFORCED CONCRETE BEAMS

The analysis of the efficiency of six types of slabs has been carried out, which differed in material, internal form and weight. The comparison and the comparison of the same in size, but different in constructive characteristics and materials of floor slabs are considered and performed.

## Finding effective thermal characteristics of composite materials based on the analysis of thermal conductivities

This paper presents a method and algorithm for finding effective thermal characteristics of composite materials, with complex internal structure by the method of thermal-electrical analogies based on the discrete model that built for the task of analysis of the temperature field by finite element method.

## Деформативні характеристики безавтоклавного пінобетону для шарів дорожнього одягу

This paper is devoted to the results of deformation characteristics of concrete and reinforced foam concrete with fiber polypropylene fiber. Tests were carried out by the standard method and a method based on the values of equality elastic modulus of concrete in compression and tension using a chart based "stress-strain".