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Wyszukujesz frazę "heat conduction problem" wg kryterium: Temat


Tytuł:
An idea of a measurement system for determining thermal parameters of heat insulation materials
Autorzy:
Chudzik, S.
Minkina, W.
Powiązania:
https://bibliotekanauki.pl/articles/220464.pdf
Data publikacji:
2011
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
thermal conductivity
artificial neural networks
inverse heat conduction problem
Opis:
The article presents the prototype of a measurement system with a hot probe, designed for testing thermal parameters of heat insulation materials. The idea is to determine parameters of thermal insulation materials using a hot probe with an auxiliary thermometer and a trained artificial neural network. The network is trained on data extracted from a nonstationary two-dimensional model of heat conduction inside a sample of material with the hot probe and the auxiliary thermometer. The significant heat capacity of the probe handle is taken into account in the model. The finite element method (FEM) is applied to solve the system of partial differential equations describing the model. An artificial neural network (ANN) is used to estimate coefficients of the inverse heat conduction problem for a solid. The network determines values of the effective thermal conductivity and effective thermal diffusivity on the basis of temperature responses of the hot probe and the auxiliary thermometer. All calculations, like FEM, training and testing processes, were conducted in the MATLAB environment. Experimental results are also presented. The proposed measurement system for parameter testing is suitable for temporary measurements in a building site or factory.
Źródło:
Metrology and Measurement Systems; 2011, 18, 2; 261-273
0860-8229
Pojawia się w:
Metrology and Measurement Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Heat conduction problem in a two-layered hollow cylinder by using the Greens function method
Autorzy:
Kukla, S.
Siedlecka, U.
Powiązania:
https://bibliotekanauki.pl/articles/122646.pdf
Data publikacji:
2013
Wydawca:
Politechnika Częstochowska. Wydawnictwo Politechniki Częstochowskiej
Tematy:
heat conduction problem
two-layered cylinder
Green's function method
Opis:
In this paper, a solution of the heat conduction problem in a two-layered hollow cylinder by using the Green’s function method is presented. The considerations concern the heat conduction in the radial direction while taking into account time-dependent boundary conditions. The continuity condition of the temperature at the dividing surface of the layers is written in the form of a Volterra integral equation.
Źródło:
Journal of Applied Mathematics and Computational Mechanics; 2013, 12, 2; 45-50
2299-9965
Pojawia się w:
Journal of Applied Mathematics and Computational Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On an application of an interval backward finite difference method for solving the one-dimensional heat conduction problem
Autorzy:
Jankowska, M.
Marciniak, A.
Hoffmann, T.
Powiązania:
https://bibliotekanauki.pl/articles/205521.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Instytut Badań Systemowych PAN
Tematy:
interval methods
interval arithmetic
finite difference methods
heat conduction problem
Opis:
The paper concerns the interval method for solving the one-dimensional heat conduction problem. It is based on the conventional backward finite difference scheme with the appropriate local truncation error terms that are also taken into account. For the theoretical formulation of the interval approach we can show that the exact solution is included in the interval one. In practice, there are problems, for which we cannot determine the endpoints of the error term intervals exactly. Nevertheless, if we use the appropriate approximation, related to the endpoints considered, then the numerical experiments confirm that the interval solution includes the exact one.
Źródło:
Control and Cybernetics; 2015, 44, 4; 463-480
0324-8569
Pojawia się w:
Control and Cybernetics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Wyznaczanie przewodności cieplnej materiałów tekstylnych przy użyciu termowizji
Thermal conductivity evaluation of textile materials using infrared measurements
Autorzy:
Felczak, M.
Michalak, M.
Więcek, B.
Powiązania:
https://bibliotekanauki.pl/articles/154532.pdf
Data publikacji:
2011
Wydawca:
Stowarzyszenie Inżynierów i Techników Mechaników Polskich
Tematy:
przewodzenie ciepła
odwrotne zagadnienia termiczne
termowizja
heat transfer
inverse heat conduction problem
Opis:
W pracy przedstawiono nową metodę wyznaczania parametrów termicznych materiałów włókienniczych, w tym także anizotropowych. Do próbek włókienniczych dostarczana jest energia cieplna i mierzona jest wartość temperatury po obu stronach materiału. Praca jest kontynuacją badań właściwości ciepłoizolacyjnych materiałów włókienniczych w dynamicznych warunkach za pomocą metody termograficznej w wykorzystaniem luster [1-6]. W stanowisku pomiarowym, którego schemat przedstawiono w cytowanych pracach zostało zastosowane źródło energii cieplnej umożliwiające szybkie nagrzewanie badanej próbki. Wykonano pomiary termowizyjne rozkładu temperatury i na podstawie uzyskanych wyników oraz modelowania termicznego wyznaczono przewodność cieplną badanych włóknin.
A new method for evaluation of homogenous anisotropic textiles thermal parameters is presented in this paper. The research is a continuation of investigating the thermal properties of textile materials [1-6]. The thermal energy was supplied to textile materials and the temperature distribution on both surfaces of the textile waas recorded using an infrared camera. The setup enabled fast textile heating. A thermal energy impulse was supplied to nonwovens. Using the obtained results and the finite element model of heat conduction, the thermal conductivity of a textile is evaluated. In order to obtain the thermal conductivity, it is necessary to solve an inversed heat conduction problem. The parameterized direct heat conduction model is used to calculate it. The research included both isotropic and anisotropic textile materials. The work was performed as a part of the Research Project 3 T08E 050 28 financed by KBN, entitled "3688/B/T02/2009/36 "The elaboration of the method of evaluation of temperature dependent thermal parameters of smart textile materials".
Źródło:
Pomiary Automatyka Kontrola; 2011, R. 57, nr 10, 10; 1223-1226
0032-4140
Pojawia się w:
Pomiary Automatyka Kontrola
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Determination of thermal diffusivity values based on the inverse problem of heat conduction - numerical analysis
Autorzy:
Adamowicz, Adam
Powiązania:
https://bibliotekanauki.pl/articles/2204678.pdf
Data publikacji:
2022
Wydawca:
Politechnika Białostocka. Oficyna Wydawnicza Politechniki Białostockiej
Tematy:
thermal diffusivity
inverse heat conduction problem
impulse heating
finite element analysis
Opis:
This paper presents a discussion on the accuracy of the method of determining the thermal diffusivity of solids using the solution of the inverse heat conduction equation. A new measurement data processing procedure was proposed to improve the effectiveness of the method. Using the numerical model, an analysis of the sensitivity of the method of thermal diffusivity determination to changes in operational and environmental parameters of the test was carried out. The obtained results showed that the method was insensitive to the parameters of the thermal excitation impulse, the thickness of the tested sample, and the significant influence of convection cooling on its accuracy. The work was completed with the formulation of general conclusions concerning the conditions for determining the thermal diffusivity of materials with the use of the described method.
Źródło:
Acta Mechanica et Automatica; 2022, 16, 4; 399--407
1898-4088
2300-5319
Pojawia się w:
Acta Mechanica et Automatica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The application of Beck’s method combined with FEM and Trefftz functions to determine the heat transfer coefficient in a minichannel
Autorzy:
Maciejewska, B.
Powiązania:
https://bibliotekanauki.pl/articles/281153.pdf
Data publikacji:
2017
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
Beck’s method
FEM
Trefftz functions
heat transfer coefficient
inverse heat conduction problem
flow boiling
Opis:
The aim of this study is to determine the heat transfer coefficient between the heated surface and the boiling fluid flowing in a minichannel on the basis of experimental data. The calculation model is based on Beck’s method coupled with the FEM and Trefftz functions. The Trefftz functions used in the Hermite interpolation are employed to construct the shape functions in the FEM. The unknown local values of the heat transfer coefficient at the foil- -fluid contact surface are calculated from Newton’s law. The temperature of the heated foil and the heat flux on the foil surface are determined by solving a two-dimensional inverse heat conduction problem. The study is focused on the identification of the heat transfer coefficients in the subcooled boiling region and the saturated nucleate boiling region. The results are compared with the data obtained through the one-dimensional method. The investigations also reveal how the smoothing of measurement data affects calculation results.
Źródło:
Journal of Theoretical and Applied Mechanics; 2017, 55, 1; 103-116
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Measurements of absorbed heat flux and water-side heat transfer coefficient in water wall tubes
Autorzy:
Taler, D.
Taler, J.
Kowal, A.
Powiązania:
https://bibliotekanauki.pl/articles/240076.pdf
Data publikacji:
2011
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
kotło parowe
odwrotne przewodzenie ciepła
strumień ciepła
żużel
heat flux meter
inverse heat conduction problem
slagging
steam boiler
Opis:
The tubular type instrument (flux tube) was developed to identify boundary conditions in water wall tubes of steam boilers. The meter is constructed from a short length of eccentric tube containing four thermocouples on the fire side below the inner and outer surface of the tube. The fifth thermocouple is located at the rear of the tube on the casing side of the water-wall tube. The boundary conditions on the outer and inner surfaces of the water flux-tube are determined based on temperature measurements at the interior locations. Four K-type sheathed thermocouples of 1 mm in diameter, are inserted into holes, which are parallel to the tube axis. The non-linear least squares problem is solved numerically using the Levenberg-Marquardt method. The heat transfer conditions in adjacent boiler tubes have no impact on the temperature distribution in the flux tubes.
Źródło:
Archives of Thermodynamics; 2011, 32, 1; 77-88
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Heating source localization in a reduced time
Autorzy:
Beddiaf, S.
Autrique, L.
Perez, L.
Jolly, J. C.
Powiązania:
https://bibliotekanauki.pl/articles/331120.pdf
Data publikacji:
2016
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
parameter identification
inverse heat conduction problem
optimal observation
source localization
identyfikacja parametryczna
odwrotne zagadnienie termiczne
obserwacja optymalna
lokalizacja źródła
Opis:
Inverse three-dimensional heat conduction problems devoted to heating source localization are ill posed. Identification can be performed using an iterative regularization method based on the conjugate gradient algorithm. Such a method is usually implemented off-line, taking into account observations (temperature measurements, for example). However, in a practical context, if the source has to be located as fast as possible (e.g., for diagnosis), the observation horizon has to be reduced. To this end, several configurations are detailed and effects of noisy observations are investigated.
Źródło:
International Journal of Applied Mathematics and Computer Science; 2016, 26, 3; 623-640
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analysis of the possibility of determining the internal structure of composite material by estimating its thermal diffusivity
Autorzy:
Kucypera, S.
Powiązania:
https://bibliotekanauki.pl/articles/240948.pdf
Data publikacji:
2014
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
mathematical model
direct problem
inverse heat conduction problem
composite material
test stand
model matematyczny
zagadnienie proste
odwrotne przewodzenie ciepła
materiał kompozytowy
stanowisko badawcze
Opis:
The aim of this paper is analysis of the possibility of determining the internal structure of the fibrous composite material by estimating its thermal diffusivity. A thermal diffusivity of the composite material was determined by applying inverse heat conduction method and measurement data. The idea of the proposed method depends on measuring the timedependent temperature distribution at selected points of the sample and identification of the thermal diffusivity by solving a transient inverse heat conduction problem. The investigated system which was used for the identification of thermal parameters consists of two cylindrical samples, in which transient temperature field is forced by the electric heater located between them. The temperature response of the system is measured in the chosen point of sample. One dimensional discrete mathematical model of the transient heat conduction within the investigated sample has been formulated based on the control volume method. The optimal dynamic filtration method as solution of the inverse problem has been applied to identify unknown diffusivity of multi-layered fibrous composite material. Next using this thermal diffusivity of the composite material its internal structure was determined. The chosen results have been presented in the paper.
Źródło:
Archives of Thermodynamics; 2014, 35, 1; 3-15
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
New technique of the local heat flux measurement in combustion chambers of steam boilers
Autorzy:
Taler, J.
Taler, D.
Sobota, T.
Dzierwa, P.
Powiązania:
https://bibliotekanauki.pl/articles/240253.pdf
Data publikacji:
2011
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
kocioł parowy
odwrotne zagadnienie przewodzenia ciepła
pomiar strumienia ciepła
żużlowanie komory paleniskowej
CFD simulation
heat flux measurement
inverse heat conduction problem
slagging of combustion chambers
steam boiler
Opis:
A new method for measurement of local heat flux to waterwalls of steam boilers was developed. A flux meter tube was made from an eccentric tube of short length to which two longitudinal fins were attached. These two fins prevent the boiler setting from heating by a thermal radiation from the combustion chamber. The fins are not welded to the adjacent water-wall tubes, so that the temperature distribution in the heat flux meter is not influenced by neighbouring water-wall tubes. The thickness of the heat flux tube wall is larger on the fireside to obtain a greater distance between the thermocouples located inside the wall which increases the accuracy of heat flux determination. Based on the temperature measurements at selected points inside the heat flux meter, the heat flux absorbed by the water-wall, heat transfer coefficient on the inner tube surface and temperature of the water-steam mixture was determined.
Źródło:
Archives of Thermodynamics; 2011, 32, 3; 103-116
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Optimum heating of cylindrical pressure components weakened by holes
Autorzy:
Dzierwa, P.
Taler, J.
Powiązania:
https://bibliotekanauki.pl/articles/240098.pdf
Data publikacji:
2012
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
kotły
naprężenie termiczne
normy
odwrotne zagadnienia przewodzenia ciepła
optymalizacja nagrzewania
zbiorniki ciśnieniowe
boiler standards
heating optimization
inverse heat conduction problem
pressure vessels
thermal stress
Opis:
A method for determining time-optimum medium temperature changes is presented. The heating of the pressure elements will be conducted so that the circumferential stress caused by pressure and fluid temperature variations at the edge of the opening at the point of stress concentration, do not exceed the allowable value. In contrast to present standards, two points at the edge of the opening are taken into consideration. The first point, P[1], is located at the cross section and the second, P[2], at the longitudinal section of the vessel. It will be shown that the optimum temperature courses should be determined with respect to the total circumferential stress at the point P[2], and not, as in the existing standards due to the stress at the point P[1]. Optimum fluid temperature changes are assumed in the form of simple time functions. For practical reasons the optimum temperature in the ramp form is preferred. It is possible to increase the fluid temperature stepwise at the beginning of the heating process and then increase the fluid temperature with the constant rate. Allowing stepwise fluid temperature increase at the beginning of heating ensures that the heating time of a thick-walled component is shorter than heating time resulting from the calculations according to EN 12952-3 European Standard. @eng
Źródło:
Archives of Thermodynamics; 2012, 33, 3; 111-121
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Nonlinear solution to a non-Fourier heat conduction problem in a slab heated by laser source
Nieliniowe rozwiązanie problemu niefourierowskiego przewodzenia ciepła w płycie nagrzewanej źródłem laserowym
Autorzy:
Noroozi, M. J.
Saedodin, S.
Ganji, D. D.
Powiązania:
https://bibliotekanauki.pl/articles/950685.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
non-Fourier heat conduction problem
nonlinear analysis
C-V model
Adomian Decomposition Method ADM
laser heating
problem niefourierowski przewodzenia ciepła
analiza nieliniowa
model C-V
metoda dekompozycji Adomiana ADM
nagrzewanie laserowe
Opis:
The effect of laser, as a heat source, on a one-dimensional finite body was studied in this paper. The Cattaneo-Vernotte non-Fourier heat conduction model was used for thermal analysis. The thermal conductivity was assumed temperature-dependent which resulted in a non-linear equation. The obtained equations were solved using the approximate-analytical Adomian Decomposition Method (ADM). It was concluded that the non-linear analysis is important in non-Fourier heat conduction problems. Significant differences were observed between the Fourier and non-Fourier solutions which stresses the importance of non-Fourier solutions in the similar problems.
W artykule badano działanie laserowego źródła ciepła na ciało jednowymiarowe o skończonych wymiarach. Do analizy rozkładu temperatury zastosowano niefourierowski model przewodnictwa ciepła Cattaneo-Vernotte. Założono, że przewodność cieplna jest zależna od temperatury, w wyniku czego otrzymano równania nieliniowe. Do rozwiązania równań zastosowano przybliżoną analityczną metodę dekompozycji Adomiana (ADM). Stwierdzono, że analiza nieliniowa ma istotne znaczenie w problemach przewodnictwa ciepła typu niefourierowskiego. Zaobserwowano istotne różnice między rozwiązaniami fourierowskimi i niefourierowskimi, co podkreśla celowość stosowania tych ostatnich w podobnych problemach.
Źródło:
Archive of Mechanical Engineering; 2016, LXIII, 1; 129-144
0004-0738
Pojawia się w:
Archive of Mechanical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Solution of the boundary value problem of heat conduction in a cone
Autorzy:
Ramazanov, Murat
Jenaliyev, Muvasharkhan
Gulmanov, Nurtay
Powiązania:
https://bibliotekanauki.pl/articles/2048719.pdf
Data publikacji:
2022
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
non-cylindrical domain
cone
boundary value problem of heat conduction
singular Volterra integral equation
Carleman–Vekua regularization method
Opis:
In the paper we consider the boundary value problem of heat conduction in a non-cylindrical domain, which is an inverted cone, i.e. in the domain degenerating into a point at the initial moment of time. In this case, the boundary conditions contain a derivative with respect to the time variable; in practice, problems of this kind arise in the presence of the condition of the concentrated heat capacity. We prove a theorem on the solvability of a boundary value problem in weighted spaces of essentially bounded functions. The issues of solvability of the singular Volterra integral equation of the second kind, to which the original problem is reduced, are studied. We use the Carleman–Vekua method of equivalent regularization to solve the obtained singular Volterra integral equation.
Źródło:
Opuscula Mathematica; 2022, 42, 1; 75-91
1232-9274
2300-6919
Pojawia się w:
Opuscula Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A sequential and global method of solving an inverse problem of heat conduction equation
Sekwencyjna i globalna metoda rozwiązania zagadnienia odwrotnego dla równania przewodnictwa ciepła
Autorzy:
Ciałkowski, M.
Grysa, K.
Powiązania:
https://bibliotekanauki.pl/articles/280136.pdf
Data publikacji:
2010
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
inverse problem
heat conduction
sequential method
global method
Opis:
The paper presents a solution to an inverse problem based on the analy- tical form of the direct problem solution in the convolutional form. The analytical form T (r, t) is a surface that is fitted to temperature patterns measured (and charged with errors) at the internal points. In the case of quickly-varying patterns, the solution to the inverse problem is highly sen- sitive to measurement errors (short sampling times). In order to obtain reliable results, the method of sequential (step by step) and global solving of the inverse problem was used together with smoothing the measurement results with the help of hyperbolic spline functions. The numerical results confirm effectiveness of the methods presented in the paper.
W pracy przedstawiono rozwiązanie zagadnienia odwrotnego w oparciu o analityczną postać rozwiązania zagadnienia prostego w postaci splotowej. Ta postać analityczna T (r, t) jest powierzchnią, która jest dopasowywana do przebiegów temperatury pomierzonej (obciążonej błędem) w punktach wewnętrznych. Dla przebiegów szybkozmiennych rozwiązanie zagadnienia odwrotnego jest bardzo wrażliwe na błędy pomiarów (małe czasy próbkowania). Dla otrzymania wiarygodnych wyników zastosowano metodę sekwencyjnego (z kroku na krok) i globalnego rozwiązywania zagadnienia odwrotnego w połączeniu z wygładzaniem wyników pomiarowych za pomocą hiperbolicznych funkcji sklejanych. Wyniki obliczeń numerycznych potwierdzają efektywność przedstawionych metod.
Źródło:
Journal of Theoretical and Applied Mechanics; 2010, 48, 1; 111-134
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On a comparison principle for a quasilinear elliptic boundary value problem of a nonmonotone type
Autorzy:
Křížek, Michal
Liu, Liping
Powiązania:
https://bibliotekanauki.pl/articles/1339322.pdf
Data publikacji:
1996
Wydawca:
Polska Akademia Nauk. Instytut Matematyczny PAN
Tematy:
comparison principle
anisotropic heat conduction
nonlinear boundary value problem
Opis:
A nonlinear elliptic partial differential equation with the Newton boundary conditions is examined. We prove that for greater data we get a greater weak solution. This is the so-called comparison principle. It is applied to a steady-state heat conduction problem in anisotropic magnetic cores of large transformers.
Źródło:
Applicationes Mathematicae; 1996-1997, 24, 1; 97-107
1233-7234
Pojawia się w:
Applicationes Mathematicae
Dostawca treści:
Biblioteka Nauki
Artykuł

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