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Thermal effects on the synthesis of acetals in a simulated moving bed adsorptive reactor

Graça, N.S.; Pais, L.S.; Silva, V.M.T.M.; Rodrigues, A.E.
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
65.84%
The effect of temperature on simulated moving bed adsorptive reactor performance was studied by simulation with both isothermal and non-isothermal mathematical models. Simulated results with isothermal mathematical model showed an improvement of SMBR performance criteria and the increase on reaction/separation regions with temperature. It was shown by simulations with non-isothermal mathematical model that the SMBR performance can be also improved by using the adiabatic operation mode. This study of the thermal effects on SMBR operation is an important step for a further implementation of energy integration concepts such as autothermal operation.

The Thermal Effects of Therapeutic Lasers with 810 and 904 nm Wavelengths on Human Skin

JOENSEN, Jon; DEMMINK, Jan Hendrik; JOHNSON, Mark I.; IVERSEN, Vegard V.; LOPES-MARTINS, Rodrigo Alvaro Brandao; BJORDAL, Jan Magnus
Fonte: MARY ANN LIEBERT INC Publicador: MARY ANN LIEBERT INC
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
45.94%
Objective: To investigate the effect of therapeutic infrared class 3B laser irradiation on skin temperature in healthy participants of differing skin color, age, and gender. Background: Little is known about the potential thermal effects of Low Level Laser Therapy (LLLT) irradiation on human skin. Methods: Skin temperature was measured in 40 healthy volunteers with a thermographic camera at laser irradiated and control (non-irradiated) areas on the skin. Six irradiation doses (2-12 J) were delivered from a 200mW, 810nm laser and a 60mW, 904nm laser, respectively. Results: Thermal effects of therapeutic LLLT using doses recommended in the World Association for Laser Therapy (WALT) guidelines were insignificant; below 1.5 degrees C in light, medium, and dark skin. When higher irradiation doses were used, the 60mW, 904 nm laser produced significantly (p < 0.01) higher temperatures in dark skin (5.7, SD +/- 1.8 degrees C at 12 J) than in light skin, although no participants requested termination of LLLT. However, irradiation with a 200mW, 810nm laser induced three to six times more heat in dark skin than in the other skin color groups. Eight of 13 participants with dark skin asked for LLLT to be stopped because of uncomfortable heating. The maximal increase in skin temperature was 22.3 degrees C. Conclusions: The thermal effects of LLLT at doses recommended by WALT-guidelines for musculoskeletal and inflammatory conditions are negligible (< 1.5 degrees C) in light...

Temperature Effects on Suction Measurement Using the Filter Paper Technique

Haghighi, Ali; Medero, Gabriela M.; Marinho, Fernando Antonio Medeiros; Mercier, Baptiste; Woodward, Peter K.
Fonte: AMER SOC TESTING MATERIALS; W CONSHOHOCKEN Publicador: AMER SOC TESTING MATERIALS; W CONSHOHOCKEN
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
55.77%
This paper presents the results of an experimental study of thermal effects on filter paper calibration curves used to obtain the soil suction. When the temperature is significantly different from ambient values, it is essential to consider the influence of temperature on the filter paper calibration curves to obtain a reliable soil suction measurement. The calibration curve of Whatman No. 42 filter paper was determined at 10 degrees C, 25 degrees C, and 50 degrees C using the vapor equilibrium technique with sodium chloride solutions at different concentrations and the axis translation technique. The experimental results showed a major influence of temperature on the filter paper calibration curves. Using the obtained experimental data a calibration equation was proposed, taking into account the effect of temperature. The obtained calibration curves were then used to determine the soil water retention curve of kaolin clay, which showed lower retention capacity at higher temperatures.

Aplicação da técnica de varredura-Z para a determinação de parâmetros térmicos.; Z-scan technique to evaluate thermal parameters.

Agnol, Fernando Fuzinatto Dall'
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 06/03/1998 PT
Relevância na Pesquisa
45.96%
A técnica de varredura-z tem sido bastante utilizada para a determinação do índice de refração não-linear (n2) em meios transparentes. Apresentamos neste trabalho uma análise teórica e resultados da técnica de varredura-z por reflexão, visando o estudo de efeitos térmicos em amostras que possuem coeficientes de absorção muito grandes. Extensões à técnica, tais como: a varredura-z resolvida no tempo e varredura-z resolvidas em freqüência puderam ser aplicadas para medir efeitos térmicos, pois estes são relativamente lentos nos materiais que medimos (água, polímero e vidro). Das componentes linear e quadrática da evolução temporal da transmitância, ou, da segunda componente de Fourier de curvas obtidas em duas freqüências, pode-se extrair parâmetros térmicos como: a capacidade térmica por unidade de massa e a difusividade térmica. Propriedades térmicas são de grande interesse na usinagem de peças, e em estudos sobre tensões estruturais e novos materiais. Pela teoria aqui desenvolvida, dada as constantes térmicas, é possível distinguir os efeitos térmicos e eletrônicos nas amostras que apresentam os dois.; The Z-Scan technique is the most popular one for the determination of the nonlinear index of refraction (n2) of transparent media. In this work we present a theoretical analysis and results of the reflection z-scan technique...

IR-visible upconversion and thermal effects in Pr3+/Yb3+-codoped Ga2O3:La2S3 chalcogenide glasses

Dos Santos, P. V.; Gouveia, E. A.; De Araujo, M. T.; Gouveia-Neto, A. S.; Ribeirot, S. J L; Benedicto, S. H S
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 10003-10010
ENG
Relevância na Pesquisa
65.96%
IR-visible upconversion fluorescence spectroscopy and thermal effects in Pr3+/Yb3+-codoped Ga2O3:La2S3 chalcogenide glasses excited at 1.064 μm is reported. Intense visible upconversion emission in the wavelength region of 480-680 nm peaked around 500, 550, 620 and 660 nm is observed. Upconversion excitation of the Pr3+ excited-state visible emitting levels is achieved by a combination of phonon-assisted absorption, energy-transfer and phonon-assisted excited-state absorption processes. A threefold upconversion emission enhancement induced by thermal effects when the codoped sample was heated in the temperature range of 20-200°C is demonstrated. The thermal-induced enhancement is attributed to a multiphonon-assisted anti-Stokes process which takes place in the excitation of the ytterbium and excited-state absorption of the praseodymium. The thermal effect is modelled by conventional rate equations considering temperature-dependent effective absorption cross-sections for the 2F7/2-2F5/2 ytterbium transition and 1G4-3P0 praseodymium excited-state absorption, and it is shown to agree very well with experimental results. Frequency upconversion in singly Pr3+-doped samples pumped at 836 nm and 1.064 μm in a two-beam configuration is also examined.

Behavior of the PMD coefficient of optical links under influence of mechanical and thermal effects

Dotto, Jeancarlo; Medeiros Neto, Januncio A. de; Pohl, Alexandre A. P.
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Conferência ou Objeto de Conferência Formato: 71-80
ENG
Relevância na Pesquisa
55.9%
This papers presents results on the variation of the PMD coefficient of optical links under influence of mechanical tests, such as tensile strength, bending and compression, and also during the application of a thermal cycle. Results revealed that the link coefficient is more influenced by the application of a tension load and also suffers significant variation under strong temperature changes. Copyrigth © SBMO.

Effects of sportswear design on thermal comfort

Abreu, Maria José Araújo Marques; Catarino, André P.; Cardoso, Cidália; Martin, Elisabeth
Fonte: Universidade do Minho Publicador: Universidade do Minho
Tipo: Conferência ou Objeto de Conferência
Publicado em /06/2011 ENG
Relevância na Pesquisa
45.98%
ISBN 978-2-7466-2858-8; Several technical developments in the sportswear clothing industry resulted in the use of functional textiles for highly-specialized performances in all kind of sports. This paper reports on an experimental investigation on the effects of garment design in thermo-physiological body comfort, measured in terms of clothing insulation for a specific outdoor sport - rowing. The thermal manikins have been used to measure clothing insulation and to evaluate the thermal comfort. Thermal manikins provide a good estimate of the total dry heat loss from the body and the distribution of heat flow over the body surface. In a standard environment, these measurements can be used to describe the thermal characteristics of clothing. Testing of sportswear clothing made of different fibers and garment designs, namely by varying knitting structures, show the possibilities of influencing thermal comfort, especially thermal insulation. The evaluation and understanding of the thermal effects of garment design and fabric materials is important for the development and optimization of functional garments. Therefore, the final aim of this paper is to study and validate the thermal comfort behaviour of active sportswear for rowing using single and multiple knitted zones in the garment design and considering also differences in material composition through thermal manikin measurements.

Influence of thermal effects on the wind field within the urban environment

Dimitrova, R.; Sini, Jean-François; Richards, K.; Schatzmann, M.; Weeks, M.; Perez García, E.; Borrego, C.
Fonte: Springer Publicador: Springer
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
65.9%
Micrometeorological conditions in the vicinity of urban buildings strongly influence the requirements that are imposed on building heating and cooling. The goal of the present study, carried out within the Advance Tools for Rational Energy Use towards Sustainability (ATREUS) European research network, is the evaluation of the wind field around buildings with walls heated by solar radiation. Two computational fluid dynamics (CFD) codes were validated against extensive wind-tunnel observations to assess the influence of thermal effects on model performance. The code selected from this validation was used to simulate the wind and temperature fields for a summer day in a specific region of the city of Lisbon. For this study, the meteorological data produced by a non-hydrostatic mesoscale atmospheric model (MM5) were used as boundary conditions for a CFD code, which was further applied to analyze the effects of local roughness elements and thermodynamic conditions on the air flow around buildings. The CFD modelling can also provide the inflow parameters for a Heating, Ventilation and Air Conditioning (HVAC) system, used to evaluate the building energy budgets and to predict performance of the air-conditioning system. The main finding of the present three-dimensional analyses is that thermal forcing associated with the heating of buildings can significantly modify local properties of the air flow.

Analysis of a porous-inclined slider bearing lubricated with magnetic fluid considering thermal effects with slip velocity

Singh,Jay Pal; Ahmad,Naseem
Fonte: Associação Brasileira de Engenharia e Ciências Mecânicas - ABCM Publicador: Associação Brasileira de Engenharia e Ciências Mecânicas - ABCM
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/09/2011 EN
Relevância na Pesquisa
55.8%
A theoretical model of a porous-inclined slider bearing lubricated with magnetic fluid has been considered together with slip velocity boundary condition. Our aim is to study the influence of various dimensionless parameters arising out of the analysis of the model. By assuming the viscosity µ = µ0 exp [-β(t m - t0)] of magnetic fluid, the expressions for mean temperature and load capacity have been obtained. It has been observed that both mean temperature field and load capacity are the functions of slip parameter, magnetic parameter, thermal parameter and permeability parameter. The dependence of the mean temperature field as well as of load capacity on these parameters has been seen graphically.

Thermal effects on the stability of circular graphene sheets via nonlocal continuum mechanics

Asemi,Saeid Reza; Farajpour,Ali; Borghei,Mehdi; Hassani,Amir Hessam
Fonte: Associação Brasileira de Ciências Mecânicas Publicador: Associação Brasileira de Ciências Mecânicas
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/08/2014 EN
Relevância na Pesquisa
55.93%
Recently, graphene sheets have shown significant potential for environmental engineering applications such as wastewater treatment. Different non-classical theories have been used for modeling of such nano-sized systems to take account of the effect of small length scale. Among all size-dependent theories, the nonlocal elasticity theory has been commonly used to examine the stability of nano-sized structures. Some research works have been reported about the mechanical behavior of rectangular nanoplates with the consideration of thermal effects. However, in comparison with the rectangular graphene sheets, research works about the nanoplates of circular shape are very limited, especially for the buckling properties with thermal effects. Hence, in this paper, an axisymmetric buckling analysis of circular single-layered graphene sheets (SLGS) is presented by decoupling the nonlocal equations of Eringen theory. Constitutive relations are modified to describe the nonlocal effects. The governing equations are derived using equilibrium equations of the circular plate in polar coordinates. Numerical solutions for buckling loads are computed using Galerkin method. It is shown that nonlocal effects play an important role in the buckling of circular nanoplates. The effects of the small scale on the buckling loads considering various parameters such as the radius of the plate...

Basic Principles and Future Aspects of Thermal Fusion and Electrocoagulation – Experimental studies in in-vitro and in-vivo rodent, porcine and human models; Grundlegende Prinzipien und zukünftige Aspekte der Thermofusion und Elektrokoagultion - Experimentelle Studie in in-vitro und in-vivo Tiermodellen sowie in humanen Modellen

Wallwiener, Christian Wilhelm
Fonte: Universidade de Tubinga Publicador: Universidade de Tubinga
Tipo: Dissertação
EN
Relevância na Pesquisa
46.05%
Bipolar vessel sealing and electrosurgery in general is pivotal in surgical and especially minimally-invasive surgical hemostasis. However, quality of vessel sealing is only suboptimal and major coaptive desiccation parameters have yet to be investigated in depth. Moreover, the potentially hazardous capacity of electrosurgery to induce both post-operative adhesions and thermal complications such as tissue necrosis has not been looked into in detail hitherto. In order to (1) optimize bipolar vessel sealing, to (2) better understand the biothermomechanics of thermal fusion, to (3) analyze the relationship between electrocoagulation and adhesion formation and to (4) develop a human in-vivo in-situ model for quantifying electrosurgery-induced thermal tissue effects and thermal tissue damage, the following studies were conducted. It was found that in an isolated porcine renal artery model, self-regulating modulation of energy-based vessel coagulation achieved superior thermal fusion of vascular tissue than CPC. This promising novel technique should therefore be further analyzed to determine its in-vivo efficacy in long-term studies. Moreover it was ascertained that compressive pressure during coaptation determines the seal quality. Upper and lower pressure boundaries for safe coaptation exist for both arteries and veins. Vessel sealing by thermal conduction without electrical current effects is possible but represents a less effective method for coaptation. These findings have implications for the rational design of new electrosurgical instruments. With regards to the adhesiogenic potential of bipolar tissue desiccation...

Theoretical estimation of thermal effects in drilling of woven carbon fiber composite

Díaz Álvarez, José; Olmedo, Álvaro; Santiuste, Carlos; Miguélez, Henar
Fonte: MDPI AG Publicador: MDPI AG
Tipo: info:eu-repo/semantics/publishedVersion; info:eu-repo/semantics/article
Publicado em /01/2014 ENG
Relevância na Pesquisa
55.94%
Carbon Fiber Reinforced Polymer (CFRPs) composites are extensively used in structural applications due to their attractive properties. Although the components are usually made near net shape, machining processes are needed to achieve dimensional tolerance and assembly requirements. Drilling is a common operation required for further mechanical joining of the components. CFRPs are vulnerable to processing induced damage; mainly delamination, fiber pull-out, and thermal degradation, drilling induced defects being one of the main causes of component rejection during manufacturing processes. Despite the importance of analyzing thermal phenomena involved in the machining of composites, only few authors have focused their attention on this problem, most of them using an experimental approach. The temperature at the workpiece could affect surface quality of the component and its measurement during processing is difficult. The estimation of the amount of heat generated during drilling is important; however, numerical modeling of drilling processes involves a high computational cost. This paper presents a combined approach to thermal analysis of composite drilling, using both an analytical estimation of heat generated during drilling and numerical modeling for heat propagation. Promising results for indirect detection of risk of thermal damage...

Thermal Effects on Monitoring and Performance of Reinforced Concrete Structures

DeRosa, DANIELLE
Fonte: Quens University Publicador: Quens University
Tipo: Tese de Doutorado
EN; EN
Relevância na Pesquisa
55.77%
Much of North America’s reinforced concrete infrastructure is reaching the end of its service life and careful inspection and assessment is required to ensure the appropriate capacity is maintained in these structures. The research conducted herein seeks to further the development of two new sensor technologies: fibre optic strain sensors and digital image correlation, which have the potential to provide comprehensive performance data for structures to a level of accuracy previously not possible. The research involves determining the accuracy of these sensor systems to monitor both strain and crack widths in reinforced concrete compared to conventional techniques, such as electrical resistance strain gauges. Preliminary work was also undertaken on correcting the sensor results for temperature. It was determined that temperature variations in the range of +21 °C to 20 °C, result in significant strain errors for both sensor systems. Once the results obtained from the sensors systems are corrected for temperature, crack widths are monitored in four small-scale reinforced concrete tension specimens, and strain and crack width behaviour is monitored in four full-scale beams under four point bending. One of the major problems faced when using the digital image correlation technique is out of plane movement which results in significant error. Techniques to lower this error are addressed. In addition...

The thermal effects on the methanol-to-olefins reaction: A modelling and experimental approach

Pereira, Sara Filipa Fagulha
Fonte: Universidade Nova de Lisboa Publicador: Universidade Nova de Lisboa
Tipo: Dissertação de Mestrado
Publicado em /09/2015 ENG
Relevância na Pesquisa
55.77%
With the projection of an increasing world population, hand-in-hand with a journey towards a bigger number of developed countries, further demand on basic chemical building blocks, as ethylene and propylene, has to be properly addressed in the next decades. The methanol-to-olefins (MTO) is an interesting reaction to produce those alkenes using coal, gas or alternative sources, like biomass, through syngas as a source for the production of methanol. This technology has been widely applied since 1985 and most of the processes are making use of zeolites as catalysts, particularly ZSM-5. Although its selectivity is not especially biased over light olefins, it resists to a quick deactivation by coke deposition, making it quite attractive when it comes to industrial environments; nevertheless, this is a highly exothermic reaction, which is hard to control and to anticipate problems, such as temperature runaways or hot-spots, inside the catalytic bed. The main focus of this project is to study those temperature effects, by addressing both experimental, where the catalytic performance and the temperature profiles are studied, and modelling fronts, which consists in a five step strategy to predict the weight fractions and activity. The mind-set of catalytic testing is present in all the developed assays. It was verified that the selectivity towards light olefins increases with temperature...

IR-visible upconversion and thermal effects in Pr3+/Yb3+-codoped Ga2O3 : La2S3 chalcogenide glasses

Santos, P. V. dos; Gouveia, E. A.; De Araujo, M. T.; Gouveia-Neto, A. S.; Ribeirot, S. J. L.; Benedicto, S. H. S.
Fonte: Iop Publishing Ltd Publicador: Iop Publishing Ltd
Tipo: Artigo de Revista Científica Formato: 10003-10010
ENG
Relevância na Pesquisa
65.96%
IR-visible upconversion fluorescence spectroscopy and thermal effects in pr(3+)/Yb3+-codoped Ga2O3:La2S3 chalcogenide glasses excited at 1.064 mum is reported. Intense visible upconversion emission in the wavelength region of 480-680 nm peaked around 500, 550, 620 and 660 nm is observed. Upconversion excitation of the Pr3+ excited-state visible emitting levels is achieved by st combination of phonon-assisted absorption, energy-transfer and phonon-assisted excited-state absorption processes. A threefold upconversion emission enhancement induced by thermal effects when the codoped sample was heated in the temperature range of 20-200 degreesC is demonstrated. The thermal-induced enhancement is attributed to a multiphonon-assisted anti-Stokes process which takes place in the excitation of the ytterbium and excited-state absorption of the praseodymium. The thermal effect is modelled by conventional rate equations considering temperature-dependent effective absorption cross-sections for the F-2(7/2)-F-2(5/2) ytterbium transition and (1)G(4)-P-3(0) praseadymium excited-state absorption, and it is shown to agree very well with experimental results. Frequency upconversion in singly Pr3+-doped samples pumped at 836 nm and 1.064 mum in a two-beam configuration is also examined.

Thermal effects in the size distribution of SiC nanodots on Si(111)

Fuenzalida, V.; Häberle, P.; Flores, M.
Fonte: Universidade do Chile Publicador: Universidade do Chile
Tipo: Artículo de revista
EN_US
Relevância na Pesquisa
55.8%
We have used scanning tunneling microscopy (STM), Auger electron spectroscopy (AES) and X-ray Photoelectron spectroscopy (XPS) to investigate the formation of nanoscopic structures on Si(111), from wafers with a high bulk C concentration. The samples were prepared by long time thermal annealing of the silicon samples, followed by a high temperature flash in ultrahigh vacuum. An increased surface C concentration is induced by segregation from the bulk. The surface is found to roughen on the nanososcopic length scale, exhibiting a random distribution of nanostructures. The height range of the structures varies between 2 and 20 nm. The size distribution is strongly dependent on the low-temperature preparation conditions. Ex-situ XPS measurements reveal the formation of SiC bonds, thus confirming the nanodots are formed by a surface recombination of SiC.

Modelling thermal effects in machining of carbon fiber reinforced polymer composites

Santiuste, Carlos; Díaz Álvarez, José; Soldani, Xavier; Miguélez, Henar
Fonte: SAGE Publicador: SAGE
Tipo: info:eu-repo/semantics/acceptedVersion; info:eu-repo/semantics/article
Publicado em /04/2014 ENG
Relevância na Pesquisa
65.98%
Machining-induced damage is commonly observed when manufacturing components based on carbon fiber reinforced polymer (CFRP) composites. Despite the importance of thermal effects in machining CFRPs, this problem has been poorly analyzed in the literature. Predictive tools are not available for thermal phenomena involved during cutting, while only few experimental studies have been found. In this paper, a three-dimensional (3D) finite element model of orthogonal machining of CFRPs including thermal effects is presented. Predicted thermal and mechanical intralaminar damage showed strong influence of fiber orientation. Thermally affected area was larger than mechanically damaged zone. This fact confirms the importance of accounting for thermal effects when modelling CFRP machining.; The authors acknowledge the financial support for the work to the Ministry of Economy and Competitiveness of Spain under the projects DPI2011-25999 and DPI2010-15123.

Thermal effects in Jaynes-Cummings model derived with low-temperature expansion

Azuma, Hiroo; Ban, Masashi
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
45.95%
In this paper, we investigate thermal effects of the Jaynes-Cummings model (JCM) at finite temperature with a perturbative approach. We assume a single two-level atom and a single cavity mode to be initially in the thermal equilibrium state and the thermal coherent state, respectively, at a certain finite low temperature. Describing this system with Thermo Field Dynamics formalism, we obtain a low-temperature expansion of the atomic population inversion in a systematic manner. Letting the system evolve in time with the JCM Hamiltonian, we examine thermal effects of the collapse and the revival of the Rabi oscillations by means of the third-order perturbation theory under the low-temperature limit, that is to say, using the low-temperature expansion up to the third order terms. From an intuitive discussion, we can expect that the period of the revival of the Rabi oscillations becomes longer as the temperature rises. Numerical results obtained with the perturbation theory reproduce well this temperature dependence of the period.; Comment: 43 pages, 6 eps figures, Latex2e; v2: a new section about thermal effects of the counter-rotating terms is added

On thermal effects in solid state lasers: the case of ytterbium-doped materials

Chenais, Sebastien; Druon, Frederic; Forget, Sebastien; Balembois, Francois; Georges, Patrick
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 05/04/2007
Relevância na Pesquisa
45.96%
A review of theoretical and experimental studies of thermal effects in solid-state lasers is presented, with a special focus on diode-pumped ytterbium-doped materials. A large part of this review provides however general information applicable to any kind of solid-state laser. Our aim here is not to make a list of the techniques that have been used to minimize thermal effects, but instead to give an overview of the theoretical aspects underneath, and give a state-of-the-art of the tools at the disposal of the laser scientist to measure thermal effects. After a presentation of some general properties of Yb-doped materials, we address the issue of evaluating the temperature map in Yb-doped laser crystals, both theoretically and experimentally. This is the first step before studying the complex problem of thermal lensing (part III). We will focus on some newly discussed aspects, like the definition of the thermo-optic coefficient: we will highlight some misleading interpretations of thermal lensing experiments due to the use of the dn/dT parameter in a context where it is not relevant. Part IV will be devoted to a state-of-the-art of experimental techniques used to measure thermal lensing. Eventually, in part V, we will give some concrete examples in Yb-doped materials...

Possibility to measure thermal effects in the Casimir force

Geyer, B.; Klimchitskaya, G. L.; Mostepanenko, V. M.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 27/08/2010
Relevância na Pesquisa
45.99%
We analyze the possibility to measure small thermal effects in the Casimir force between metal test bodies in configurations of a sphere above a plate and two parallel plates. For sphere-plate geometry used in many experiments we investigate the applicability of the proximity force approximation (PFA) to calculate thermal effects in the Casimir force and its gradient. It is shown that for real metals the two formulations of the PFA used in the literature lead to relative differences in the obtained results being less than a small parameter equal to the ratio of separation distance to sphere radius. For ideal metals the PFA results for the thermal correction are obtained and compared with available exact results. It is emphasized that in the experimental region in the zeroth order of the small parameter mentioned above the thermal Casimir force and its gradient calculated using the PFA (and thermal corrections in their own right) coincide with respective exact results. For real metals available exact results are outside the application region of the PFA. However, the exact results are shown to converge to the PFA results when the small parameter goes down to the experimental values. We arrive at the conclusion that large thermal effects predicted by the Drude model approach...