Identification of Discontinuous Thermal Conductivity Coefficient Using Fast Automatic Differentiation

2017 ◽  
pp. 295-300 ◽  
Author(s):  
Alla F. Albu ◽  
Yury G. Evtushenko ◽  
Vladimir I. Zubov
Keyword(s):  
Thermal Conductivity ◽  
Thermal Conductivity Coefficient ◽  
Automatic Differentiation ◽  
Fast Automatic Differentiation

scholarly journals APPLICATION OF FAST AUTOMATIC DIFFERENTIATION TO SOLVING THE INVERSE COEFICIENT PROBLEMS

2020 ◽  
pp. 004-014
Author(s):  
YU. G. EVTUSHENKO ◽  
◽  
V. I. ZUBOV ◽  
A. F. ALBU ◽  
◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Heat Flux ◽  
Dirichlet Boundary ◽  
Thermal Conductivity Coefficient ◽  
Automatic Differentiation ◽  
Dirichlet Boundary Value Problem ◽  
Temperature Dependent ◽  
Fast Automatic Differentiation ◽  
Temperature Dependent Thermal Conductivity ◽  
Differentiation Technique

The inverse problem under consideration is to determine a temperature-dependent thermal conductivity coefficient from experimental observations of the temperature field in the studied substance and (or) the heat flux on the surface of the object. The study is based on the Dirichlet boundary value problem for the nonstationary heat equation stated in the general n -dimensional formulation. For the numerical solution of the problem an algorithm based on the modern fast automatic differentiation technique is proposed.

The effect of variable properties and rotation in a visco-thermoelastic orthotropic annular cylinder under the Moore–Gibson–Thompson heat conduction model

2021 ◽  
pp. 146442072098589
Author(s):  
Ahmed E Aboueregal ◽  
Hamid M Sedighi
Keyword(s):  
Thermal Conductivity ◽  
Thermal Stresses ◽  
Thermal Conductivity Coefficient ◽  
Variable Properties ◽  
Transformation Technique ◽  
Present Contribution ◽  
Conduction Model ◽  
Thermoelastic Model ◽  
Shock Heating ◽  
Physical Fields

The present contribution aims to address a problem of thermoviscoelasticity for the analysis of the transition temperature and thermal stresses in an infinitely circular annular cylinder. The inner surface is traction-free and subjected to thermal shock heating, while the outer surface is thermally insulated and free of traction. In this work, in contrast to the various problems in which the thermal conductivity coefficient is considered to be fixed, this parameter is assumed to be variable depending on the temperature change. The problem is studied by presenting a new generalized thermoelastic model of thermal conductivity described by the Moore–Gibson–Thompson equation. The new model can be constructed by incorporating the relaxation time thermal model with the Green–Naghdi type III model. The Laplace transformation technique is used to obtain the exact expressions for the radial displacement, temperature and the distributions of thermal stresses. The effects of angular velocity, viscous parameter, and variance in thermal properties are also displayed to explain the comparisons of the physical fields.

scholarly journals INFLUENCE OF LIGHTWEIGHT FILLERS ON THE PERFORMANCE OF CEMENT-BASED SKIM COAT

2020 ◽  
Vol 12 (1) ◽  
pp. 5-11
Author(s):  
MARCIN KUPIŃSKI ◽  
KAROLINA STOBIENIECKA ◽  
KAROL SKOWERA
Keyword(s):  
Thermal Conductivity ◽  
Thermal Conductivity Coefficient ◽  
Pozzolanic Reaction ◽  
Vapor Condensation ◽  
Cement Matrix ◽  
Capillary Absorption ◽  
Mold Growth ◽  
Expanded Perlite ◽  
Water Vapor Condensation ◽  
Effective Additive

Lightweight fillers are used in dry-mixed building mortars in order to improve thermal insulation properties, yield, and workability. In the case of thin layer products, used as a finishing layer, reduced thermal conductivity coefficient enables to restrain of water vapor condensation on walls – which inhibits mold growth. The aim of the study was to determine the influence of 4 types of lightweight fillers on the performance of cement-based skim coat – with emphasis on the economic aspect. Formulas reflecting typical commercial products were used. The dosage of different components -such as expanded perlite, glass and polymeric bubbles or expanded glass – was optimized for sufficient yield and workability, keeping the constant price of 1 kg of the final product. Mechanical parameters, capillary absorption coefficient, and thermal conductivity coefficient were determined. Observations by Scanning Electron Microscope revealed poor incorporation of polymer microspheres in the cement matrix, leading to loss of mechanical strength. With the addition of expanded glass, an increase of flexural and compressive strength thanks to the pozzolanic reaction was observed. Glass bubbles were found the most effective additive.

scholarly journals Effects of pressure and temperature on thermal contact resistance between different materials

2015 ◽  
Vol 19 (4) ◽  
pp. 1369-1372 ◽  
Author(s):  
Zhe Zhao ◽  
Hai-Ming Huang ◽  
Qing Wang ◽  
Song Ji
Keyword(s):  
Thermal Conductivity ◽  
Contact Resistance ◽  
Thermal Contact Resistance ◽  
Experimental Approach ◽  
Phenolic Resin ◽  
Thermal Conductivity Coefficient ◽  
Thermal Contact ◽  
Carbon Composites ◽  
Interfacial Temperature ◽  
Temperature And Pressure

To explore whether pressure and temperature can affect thermal contact resistance, we have proposed a new experimental approach for measurement of the thermal contact resistance. Taking the thermal contact resistance between phenolic resin and carbon-carbon composites, cuprum, and aluminum as the examples, the influence of the thermal contact resistance between specimens under pressure is tested by experiment. Two groups of experiments are performed and then an analysis on influencing factors of the thermal contact resistance is presented in this paper. The experimental results reveal that the thermal contact resistance depends not only on the thermal conductivity coefficient of materials, but on the interfacial temperature and pressure. Furthermore, the thermal contact resistance between cuprum and aluminum is more sensitive to pressure and temperature than that between phenolic resin and carbon-carbon composites.

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