Wyniki wyszukiwania - Biblioteka Nauki

1

Impact of tissue parameters on temperature distribution in interstitial microwave hyperthermia

100%

Gas P.

Zeszyty Naukowe. Elektryka / Politechnika Łódzka

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2012

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tom z. 124

47-55

EN

The paper attempts to show the application of interstitial microwave hyperthermia in treatment of pathological human tissues. For simplification, a 2D model of the coaxial-slot antenna is considered. Electromagnetic field radiated from the antenna in TM wave form is a source of the temperature gradient in the tissue. Therefore, besides the wave equation, the Pennes equation under steady-state condition is examined. Influence of the parameters of the different tissues, with particular emphasis on permittivity as well as electrical and thermal conductivity, on temperature distribution is investigated. All simulation results have been calculated using the finite element method for the antenna operating frequency of 2.45 GHz and the antenna input power level set to 1 W.

PL

Artykuł pokazuje zastosowanie śródmiąższowej hipertermii mikrofalowej w leczeniu patologicznych tkanek ludzkich. Dla uproszczenia przedstawiono 2D model anteny współosiowej ze szczeliną powietrzną. Pole elektromagnetyczne wytwarzane przez antenę w postaci fali TM stanowi źródło gradientu temperatury w tkance. Z tego względu, oprócz równania falowego, rozpatrzono równanie Pennesa w przypadku stacjonarnym. Zbadano wpływ parametrów różnych tkanek na rozkład temperatury ze szczególnym uwzględnieniem przenikalności elektrycznej oraz przewodności elektrycznej i cieplnej poszczególnych tkanek. Wyniki symulacji zostały wyznaczone przy użyciu metody elementów skończonych dla częstotliwości pracy anteny 2,45 GHz oraz poziomu mocy wejściowej anteny 1 W.

2

Porównanie rozkładów pól temperatury we wsadach nagrzewanych indukcyjnie zamodelowanych jako bezźródłowe lub źródłowe

100%

Cichoń D. , Pasternak J.

Zeszyty Naukowe. Elektryka / Politechnika Łódzka

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2001

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tom z. 97

17-24

PL

W referacie przeanalizowano rozkłady pól temperatury we wsadach nagrzewanych indukcyjnie w oparciu o różne modele. Badano modele z wewnętrznymi i zewnętrznymi źródłami ciepła. Porównano rozwiązania otrzymane numerycznie z analitycznym rozwiązaniem równania przewodnictwa ciepła, formalizującym prawo Fouriera-Kirchhoffa.

EN

The paper deals with an analysis of temperature distribution in induction heated furnace charges. The analysis was performed on the basis of various models, both with internal as well as external heat sources. The numerically obtained results were compared with analytical solutions of the equation describing the conduction of heat according to the Fourier-Kirchoff law.

3

Remarks on an inverse modelling of welding processes

100%

Ranatowski E.

Advances in Materials Science

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2005

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tom Vol. 5, nr 1-3

21-31

EN

At the beginning of this work a short characteristic of the methodology of modelling rules of welding process is provided. The relation between both the intensive and extensive parameters are mainly discussed. Additionally, the theoretical bases of modelling of welding processes are presented. In further on the bases of modelling of inverse heat conduction problem is talked over. It bases on the strategy of solving inverse problems [2], it employs the hybrid an analytic - numerical method for analysis these questions. Finally, the appropriate algorithms in moving and stationary systems are established which can be directly applied to solving inverse problem.

4

Distributions of hydrodynamic pressure in the gap of slide journal bearing lubricated with ferro-oil

100%

Frycz M.

Journal of KONES

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2019

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tom Vol. 26, No. 4

53--61

EN

This research work is part of a broader comprehensive issue, which is the analysis of flow and operating parameters of journal slide bearings lubricated with ferro-oil. In this article, the author presents only the main assumptions and essential transformations of the analytical and numerical model for determining the pressure distributions in the gap of a slide journal bearing lubricated with ferro-oil. It is cardinal that the rheological and magnetic values of ferro-oil parameters adopted in numerical calculations are based on the results of actual values obtained in the author’s earlier research work. There are presented the pressure distributions by abovementioned method in the article for cases of bearings lubricated with ferro-oils with different concentration of magnetic particles. The obtained results are shown in the form of a set of four complementary characteristics of the dimensionless pressure distributions. First and main of them are the calculations for classical Newtonian lubrication but they take into account the influence of the magnetic field on the distributions. The next of the presented characteristics are so-called "corrections" of pressure distribution values, taking into account as follows: effects of changes in ferro-oil viscosity related to temperature changes, impacts of ferro-oil viscosity changes related to pressure changes and the effect of non-oil properties of the lubricant. The article includes a qualitative and quantitative analysis of the obtained results as well as observations and conclusions are presented in it.

5

Experimental values of temperature distribution in a sliding bearing sleeve lubricated with non-Newtonian oils

100%

Miszczak A.

Polish Maritime Research

|

2005

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tom nr 3

16-26

EN

This paper presents results of experimental investigations of temperature distributions on inner surface of a sleeve of transverse sliding bearing lubricated with non-Newtonian oils. The measurements were performed by means of Pt100 miniature sensors placed close to internal surface of the sleeve. To measure sleeve temperature distributions use was made of a test stand installed at Gdynia Maritime University. Delo 1000 Marine 30 oil, SAE 15W40 basic oil, and aferro-oil made of the SAE 15W40 basic oil were used as a lubricating medium. During measuring temperature distributions for the ferro-oil different intensity values of external magnetic field generated by electromagnets were applied.

6

Termograficzna ocena rozkładu temperatury na powierzchni przedmiotu obrabianego podczas toczenia nieortogonalnego

100%

Jóźwik J.

Eksploatacja i Niezawodność

|

2001

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tom nr 5

58-61

PL

W artykule przedstawiono termograficzną analizę rozkładu temperatury na powierzchni przedmiotu obrabianego podczas toczenia nieortogonalnego. W postaci wykresów przedstawiono rozkład temperatury na powierzchni przedmiotu obrabianego w funkcji położenia źródła ciepła oraz czasu. Pomiary prowadzono przy użyciu kamery termograficznej typu V-20ER005-25 wyprodukowanej przez firmę VIGO SYSTEM z Warszawy. Dane termograficzne analizowano przy wykorzystaniu specjalistycznego oprogramowania TERMOGRAF v.1.95 c.

EN

The thermographic analysis of temperature distribution on surface of workpiece during non-orthogonal turning is presented in the article. The distribution of temperature on the surface ofworkpiece in function of moving heat source and lime is shown inform of graphs. Measurements were performed with thermographic camera ofV-20ER005-25 type, produced by VIGO SYSTEM in Warsaw. Thermografic data were analysed with specialistic THERMOGRAPH v. 1. 95 c software.

7

The model of winter night-time temperature distribution in Łódź

100%

Fortuniak K. , Kłysik K. , Uniwersytet Łódzki Z. M. i. K.

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tom 3

PL

Opracowanie zawiera prosty model przestrzennego zróżnicowania miejskiej wyspy ciepła w Łodzi podczas bezchmurnych, zimowych nocy. Zmiany temperatury powietrza na terenie miasta (dT) obliczone zostały na podstawie spadków temperatury na obszarach zamiejskich (dT) z wykorzystaniem zależności dT u = A . dT,. Formułę tę stosowano dla poszczególnych sektorów miasta (komórki 500 x 500 m) o różnym stopniu urbanizacji, z krokiem czasowym równym 100 min. Współczynnik A dobrany został zależnie od prędkości wiatru i stopnia urbanizacji. Dodatkowo po każdym kroku iteracji stosowano procedurę wygładzającą pole temperatury zależnie od prędkości wiatru. Mimo prostoty, model w zadowalający sposób opisuje zarówno przestrzenny rozkład temperatury, jak i czasowy rozwój miejskiej wyspy ciepła (rys. 2-5).

EN

In the paper a simply model of the um shape in Łódź during cloudless, winter night is presented. Decreases of the temperature in the city (dT J were calculated with the aid of rural temperature decreases (dT,) basing on the relation: dTu =A ·dT,. This formula was applied to the city sectors (cells 500 x 500 m) with different urbanization ratio with the time step equal 10 min. Factor A was choosen empirically depending on wind speed and urbanization ratio. Additionally, in each iteration temperature field was smoothed proportionally to the wind speed. In spite of simplicity the model well describe temporal evolution and spatial distribution of the UHI.

8

Experimental testing of the vehicle heating system

100%

Kucybała P. , Gawlik A.

Journal of KONES

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2017

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tom Vol. 24, No. 3

135--141

EN

An important problem in the design of machinery and equipment at the stage of determining their structure is the issue of providing adequate thermal comfort to users while operating in variable climatic and environmental conditions. This issue is of particular importance because all types of machinery and devices are equipped with very expensive and automated control and monitoring system, which should guarantee adequate warming conditions and should work under different climatic conditions. Examples of these tendencies are special solutions for vibroacoustic insulation of the inside of the devices, special air conditioning equipment, special constructions, ergonomic inside solutions. The process of shaping the discussed structural design of vehicles in terms of meeting the relevant technical and operational criteria is currently being increasingly realized through experimental tests of prototypes supported by numerical calculations. The purpose of this paper is to present the methodology of conducting test stand as a stage for the experimental determination and verification of temperature distribution, the location of heating and air conditioning devices in a prototype vehicle in variable climatic conditions (minus 15º C). The research was carried out in a large-scale climate chamber. It covered the process of heating up the passenger area of the bus and the time of temperature stabilization on the inside of the vehicle while operating the heating systems. An additional attempt was made to test the heating system while the vehicle was in motion and to open the vehicle door to simulate the stopping of the vehicle at the bus stop. Another aspect that was analysed was the impact of the installed convector on the vehicle when the liquid heater was off.

9

Variation of temperature field created at pulsed laser irradiation of amorphous Fe73.7Si15.5B7.4Nb2.4Cu1.0 alloy

100%

Nykyruy Y. S. , Mudry S. I.

TASK Quarterly : scientific bulletin of Academic Computer Centre in Gdansk

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2015

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tom Vol. 19, No 1

75--82

EN

The temperature in the laser irradiation area of an amorphous iron-based ribbon was calculated. As a result of the calculation a spatial temperature distribution and its time dependence were structured which allowed reproducing the geometric and structural characteristics of exposed areas. Simultaneously, an irradiated amorphous alloy was investigated by scanning electron microscopy which allowed determining the geometric and structural characteristics of these areas experimentally and obtaining their dependencies on the laser pulse parameters. The results of theoretical calculations were compared with the experimental data.

10

Numerical thermal analysis of a car braking system

100%

Różyło P.

Advances in Science and Technology. Research Journal

|

2017

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tom Vol. 11, no 2

38--43

EN

The study involved performing a numerical thermal analysis of selected components in a car braking system. The primary goal of the study was to determine the regions which are most susceptible to variations in temperature, and to determine the degree of thermal impact upon them. The analysis was performed using the Abaqus environment. The examined components of the braking system were made of materials reflecting mechanical properties of the real subassemblies. The FEM analysis enabled determination of the distribution of temperature in the system with respect to the properties of the investigated materials and applied boundary conditions.

11

The Numerical Modeling of Thermal Stress Distribution in Thermal Barrier Coatings

100%

Jasik A.

Archives of Metallurgy and Materials

|

2017

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tom Vol. 62, iss. 3

1433--1437

EN

The paper presents the results of numerical calculations of temperature and thermal stress distribution in thermal barrier coatings deposited by thermal spraying process on the nickel based superalloy. An assumption was made to apply conventional zirconium oxide modified with yttrium oxide (8YSZ) and apply pyrochlore type material with formula La2Zr2O7. The bond coat was made of NiCoCrAlY. Analysis of the distribution of temperature and stresses in ceramic coatings of different thicknesses was performed in the function of bond-coat thickness and the type of ceramic insulation layer. It was revealed that the thickness of NiCrAlY bond-coat has not significant influence on the stress distribution, but there is relatively strong effect on temperature level. The most important factor influenced on stress distribution in TBC system is related with type and properties of ceramic insulation layer.

12

The inﬂuence of temperature on dynamics of the rotor – foil bearing system

100%

Bagiński P. , Żywica G.

Transactions of the Institute of Fluid-Flow Machinery

|

2016

|

tom nr 134

11--28

EN

The paper presents the research on the eﬀect of elevated temperature on the dynamic performance of a rotor supported by foil bearings. The tests were carried out on the test rig equipped with a module for increasing temperature around the bearings. A 3 kW motor with two ceramic ball bearings was connected to the shaft by means of a ﬂexible coupling. The shaft was supported by gas foil bearings. The maximum rotational speed of the rotor was 24000 rpm. The tests were performed with the operating rotor, covering multiple start and stop cycles at room and elevated temperatures. During the ﬁrst stage of experimental investigation vibration, displacement and temperature values for the two bearings were recorded. Then, the temperature was raised to approx. 200 ◦C within one of the bearing supports. The parameters mentioned above were registered and compared with the results obtained during room temperature operation. After each test bearings were disassembled, regenerated as necessary and reassembled. After analysis of the results achieved, it could be noted that the system was sensitive to the altering of operating conditions of the rotor. The elevated temperature around the shaft has increased its diameter, thereby reducing the lubricating gap. In spite of adverse operating conditions aﬀecting the rotor, the whole system operated in a safe and stable manner.

13

On temperature distributions in a semi-infinite periodically stratified layer

100%

Kulchystyky-Zhyhailo R. , Matysiak S. J.

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2006

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tom Vol. 54, nr 1

45-49

EN

The paper presents same problems of beat conduction in a semi-infinite periodically stratified layer. The layer is subjected to acting a constant temperature on the part of boundary, normal to the layering. The tree beat exchange with surroundings is assumed on the remaining part of the boundary. The composite layer is supposed to be composed of n periodically repeated two-component lamina. The problem is solved in two ways: (1°) directly as a beat conduction problem, (2°) by using model with microlocal parameters [1,2]. The main aim of the paper is a comparison of the obtained results and to conclude possibilities of applications of the homogenized model with microlocal parameters.

14

Thermal models of pulse electrochemical machining

100%

Kozak J.

Bulletin of the Polish Academy of Sciences. Technical Sciences

|

2004

|

tom Vol. 52, nr 4

313-320

EN

Pulse electrochemical machining (PECM) provides an economical and effective method for machining high strength, heat-resistant materials into complex shapes such as turbine blades, die, molds and micro cavities. Pulse Electrochemical Machining involves the application or a voltage pulse at high current density in the anodic dissolution process. Small interelectrode gap, Iow electrolyte flow rate, gap state recovery during the pulse off-times lead to improved machining accuracy and surface finish when compared with ECM using continuous current. This paper presents a mathematical model for PECM and employs this model in a computer simulation of the PECM process for determination of the thermal limitation and energy consumption in PECM. The experimental results and discussion of the characteristics PECM are presented.

15

Heat dissipation and temperature distribution in long interconnect lines

100%

Gnidzińska K. , Mey G. , Napieralski A.

Bulletin of the Polish Academy of Sciences. Technical Sciences

|

2010

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tom Vol. 58, nr 1

119-124

EN

Thermal and time delay aspects of long interconnect lines have been investigated. To design a modern integrated circuit we need to focus on very long global interconnects in order to achieve the desired frequency and signal synchronization. The long interconnection lines introduce significant time delays and heat generation in the driver transistors. Introducing buffers helps to spread the heat production more homogenously along the line but consumes extra power and chip area. To ensure the functionality of the circuit, it is compulsory to give priority to the time delay aspect and then the optimized solution is found by making the power dissipation as homogenous as possible and consequently the temperature distribution T (relative to ambient) as low as possible. The technology used for simulations is 65 nm node. The occurring phenomena have been described in a quantitative and qualitative way.

16

Shape sensitivity analysis of temperature distribution in a non-homogeneous domain

100%

Freus K. , Freus S.

Prace Naukowe Instytutu Matematyki i Informatyki Politechniki Częstochowskiej

|

2012

|

tom Vol. 11, nr 2

33-41

EN

The heated non-homogeneous domain from the two sub-domains compound is considered. The temperature distribution is described by the system of two Laplace equations. At the surface Γ c between sub-domains the ideal contact is assumed, at the remaining surfaces the Dirichlet, Neumann and Robin conditions are taken into account. The problem is solved by means of the boundary element method. To estimate the changes of temperature due to the change of local geometry of internal boundary Γ c the implicit variant of shape sensitivity analysis is applied. In the final part, the results of computations are shown and the conclusions are formulated.

17

Formula for temperature distribution in multi-layer optical fibres for high-power fibre lasers

100%

Grábner M. , Peterka P. , Honzátko P.

Opto-Electronics Review

|

2021

|

tom Vol. 29, No. 4

126--132

EN

High power fibre lasers need to be cooled efficiently to avoid their thermal damage. Temperature distribution in fibre should be estimated during the fibre laser design process. The steady-state heat equation in a cylindrical geometry is solved to derive a practical formula for temperature radial distribution in multi-layered optical fibres with arbitrary number of the layers. The heat source is located in one or more cylindrical domains. The validity of the analytical formula is tested by comparison with static heat transfer simulations of typical application examples including octagonal double clad fibre, air-clad fibre, fibre with nonuniform, microstructured core. The accuracy sufficient for practical use is reported even for cases with not exactly cylindrical domains.

18

Modelowanie rozkładu temperatury w powłokowych barierach cieplnych

88%

Jasik A.

Rudy i Metale Nieżelazne Recykling

|

2016

|

tom R. 61, nr 2

78--82

PL

W artykule przedstawiono przykład zastosowania obliczeń numerycznych metodą elementów skończonych, jako narzędzia charakteryzującego rozkład temperatury w powłokowych barierach cieplnych o różnego rodzaju ceramicznych warstwach izolacyjnych. Dokonano analizy rozkładu temperatury w powłokach o różnej grubości. Założono zastosowanie konwencjonalnego tlenku cyrkony modyfikowanego tlenkiem itru (8YSZ) oraz nowego typu materiału ceramicznego z grupy tzw. pirochlorów o wzorze La2Zr2O7.

EN

The paper presents an example of application of numerical calculations using finite element method as a tool of temperature distribution characterization in thermal barrier coatings based on different type pf outer ceramic insulation layers. The paper shows the results of the temperature distribution in ceramic layers with different thickness. As an outer layer the conventional yttria stabilized zirconia (8YSZ) and pyrochlore type material with formula La2Zr2O7 were used.

19

Bench Tests for Exhaust Gas Temperature Distribution in an Aircraft Piston Engine with and without a Turbocharger

88%

Czarnigowski J. A. , Skiba K. , Rękas D. , Ścisłowski K. , Jakliński P.

Advances in Science and Technology. Research Journal

|

2021

|

tom Vol. 15, no 3

155--166

EN

In ultralight aviation, a very important engine parameter is the power-to-weight ratio. On the one hand, there is a tendency to minimize the size and weight of engines, and on the other hand, there is a demand to achieve the highest possible power by using supercharging systems. Increasing power brings many benefits, but it also increases temperature in the exhaust system, posing a threat to delicate parts of the ultralight aircraft fuselage. Therefore, it is necessary to control temperature values in the engine exhaust system. This article presents the temperature distribution in the exhaust system of an aircraft engine by the example of a four-cylinder Rotax 912 engine with an electronic fuel injection system. The research was conducted in two stages: measurements were made first for the engine without a turbocharger with an original exhaust system and later for its modified version with an added turbocharger system. The paper presents a comparative analysis of exhaust gas temperatures measured at three points: 30, 180 and 1000 mm from the cylinder head. The tests were conducted for the same preset engine operating conditions at constant speed and manifold air pressure. It has been shown that the exhaust temperature in the exhaust manifold decreases with the distance from the cylinder head. The highest gradient, over three times higher than the gas temperature from 589.9 °C to 192.3 °C, occurred in the manifold with a turbocharger for 2603 RPM and 31 kPa of manifold air pressure. The introduction of turbocharging causes an increase in exhaust gas temperatures before the turbocharger by an average of 12%, with this increase being greater for operating points of higher inlet manifold pressure. Turbocharging also causes a significant decrease in exhaust gas temperatures behind the turbocharger and the silencer because the temperature drops there by an average of 25%.

20

Effect of hydrostatic initial stress in Green-Naghdi (Type III) thermoelastic half-space subjected to ramp-type heating and loading

88%

Ailawalia P.

Journal of Technical Physics

|

2009

|

tom Vol. 50, no 4

403-415

EN

The Green and Naghdi theory of thermoelasticity is employed to study the deformation of thermoelastic solid half-space under hydrostatic initial stresses, subjected to ramp-type heating and loading at the free surface. A linear temperature ramping function is used to more realistically model thermal loading of the half-space surface. The components of displacement, stress arid temperature distribution are obtained in Laplace and Fourier domain by applying integral transforms. These components are then obtained in the physical domain by applying a numerical inversion method. Numerical computations are carried out for a particular example of the model. The results are also presented graphically to show the effect of hydrostatic initial stress and ramping parameter in the medium.