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  • 1
    Electronic Resource
    Electronic Resource
    Thermal conductivity of CVD diamond films (1996)
    Springer
    International journal of thermophysics 17 (1996), S. 695-703 
    Details
    ISSN: 1572-9567
    Keywords: AC calorimetry ; CVD diamond film ; Debye phonon model ; grain boundary ; thermal conductivity ; thermal diffusivity ; U-process
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Diamond films 60 and 170 µm in thickness were grown by PACVD (plasma-assisted chemical vapor deposition) under similar conditions. The thermal diffusivity of these freestanding films was measured between 100 and 300 K using AC calorimetry. Radiation heat loss from the surface was estimated by analyzing both the amplitude and the phase shift of a lock-in amplifier signal. Thermal conductivity was calculated using the specific heat data of natural diamond. At room temperature, the thermal conductivity of the 60 and 170 υm films is 9 and 16 W-cm−1. K−1 respectively, which is 40–70% that of natural diamond, The temperature dependence of thermal conductivity of the CVD diamond films is similar to that of natural diamond, Phonon scattering processes are considered using the Debye model, The microsize of the grain boundary has a significant effect on the mean free path of phonons at low temperatures. The grain in CVD diamond film is grown as a columnar structure, Thus, the thicker film has the larger mean grain size and the higher thermal conductivity. Scanning electron microscopy (SEM) and Raman spectroscopy were used to study the microstructure of the CVD diamond films. In this experiment, we evaluated the quality of CVD diamond film of the whole sample by measuring the thermal conductivity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01441515
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  • 2
    Electronic Resource
    Electronic Resource
    Measurement of the Thermal Conductivity of Si and GaAs Wafers Using the Photothermal Displacement Technique (1998)
    Springer
    International journal of thermophysics 19 (1998), S. 281-290 
    Details
    ISSN: 1572-9567
    Keywords: GaAs ; impurities ; phonons ; photothermal displacement technique ; semiconductors ; Si ; thermal conductivity ; thermal diffusivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Thermal conductivity and thermal diffusivity of Si and GaAs wafers were measured using the photothermal displacement technique, and the temperature dependence of these two quantities was investigated. Thermal diffusivity was obtained from the phase difference between the heating source and the signal, and thermal conductivity was determined from the maximum value of the signal amplitude in the temperature range 80 to 300 K. It was verified that an increase in doping concentration gives rise to a decrease in thermal conductivity at low temperatures. The experimental results obtained on samples with different types and doping concentrations are consistent with those expected from theoretical considerations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1021467606454
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  • 3
    Electronic Resource
    Electronic Resource
    Thermal Diffusivity Measurement of Two-Layer Optical Thin-Film Systems Using Photoacoustic Effect1 (2000)
    Springer
    International journal of thermophysics 21 (2000), S. 543-552 
    Details
    ISSN: 1572-9567
    Keywords: antireflection coating ; parameter estimation ; photoacoustic effect ; thermal diffusivity ; through-plane
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract In this study, we designed and developed two-layer antireflection (AR) optical coating samples on glass substrates, using different evaporation conditions of coating rates and substrate temperatures for two dielectric materials, MgF2 and ZnS, with different refractive indices. The through-plane thermal diffusivity of these systems was measured using the photoacoustic effect. The optical thicknesses of MgF2 and ZnS layers were fixed at 5λ/4 (λ=514.5 nm) and λ, respectively, and the thermal diffusivities of the samples were obtained from the measured amplitude of the photoacoustic signals by changing the chopping frequency of the Ar+ laser beam. The results demonstrated that the thermal diffusivity of the sample fabricated under the conditions of 10μÅ·s−1 and 150°C had the maximum value and that the results were directly related to the microstructure of the film system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006612403028
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  • 4
    Electronic Resource
    Electronic Resource
    On a finite element CFD algorithm for compressible, viscous and turbulent aerodynamic flowsBased as an invited lecture. (1987)
    Chichester : Wiley-Blackwell
    International Journal for Numerical Methods in Fluids 7 (1987), S. 1235-1259 
    Details
    ISSN: 0271-2091
    Keywords: Fluid Mechanics ; CFD ; Finite Element ; Accuracy/Convergence ; Stability ; PNS/TLNS ; Turbulent ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: This paper develops and analyses individual construction aspects of an efficient and accurate finite element algorithm for prediction of viscous and turbulent flow fields of impact in aerodynamics. The theoretical construction employs a Taylor weak statement (TWS) for coincident embedding of stability mechanisms within a classic Galerkin finite element formulation of semi-discrete approximation error orthogonalization. A wide variety of the stabilizing mechanisms of independently derived CFD algorithms are contained within the TWS theory. An implicit construction that meets the requirement of efficient convergence to steady state is developed. The theoretical asymptotic error estimates of the TWS finite element algorithm for supersonic and viscous boundary layer flows are verified. Application to a three-dimensional turbulent flow is cited.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/fld.1650071107
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  • 5
    Electronic Resource
    Electronic Resource
    A taylor weak-statement algorithm for hyperbolic conservation laws (1987)
    Chichester : Wiley-Blackwell
    International Journal for Numerical Methods in Fluids 7 (1987), S. 489-520 
    Details
    ISSN: 0271-2091
    Keywords: CFD Algorithm ; Weak Statement ; Hyperbolic ; Parabolic ; Dissipation ; Dispersion ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Finite element analysis, applied to computational fluid dynamics (CFD) problem classes, presents a formal procedure for establishing the ingredients of a discrete approximation numerical solution algorithm. A classical Galerkin weak-statement formulation, formed on a Taylor series extension of the conservation law system, is developed herein that embeds a set of parameters eligible for constraint according to specification of suitable norms. The derived family of Taylor weak statements is shown to contain, as special cases, over one dozen independently derived CFD algorithms published over the past several decades for the high speed flow problem class. A theoretical analysis is completed that facilitates direct qualitative comparisons. Numerical results for definitive linear and non-linear test problems permit direct quantitative performance comparisons.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/fld.1650070505
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  • 6
    Electronic Resource
    Electronic Resource
    A SIMPLE AND EFFICIENT MIXED FINITE ELEMENT FOR AXISYMMETRIC SHELL ANALYSIS (1996)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 39 (1996), S. 1903-1914 
    Details
    ISSN: 0029-5981
    Keywords: axisymmetric shell ; mixed finite element ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: An efficient, perhaps simplest, three-noded mixed finite element is proposed for axisymmetric shell analysis. The key feature in the present formulation is to start with a better variational principle in which the independent unknowns are only the quantities that can be prescribed at the shell edges. If the consistency for field approximations is satisfied, no other numerical consideration is necessary in the present element. Several examples confirm the satisfactory numerical behaviour of the present mixed element.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 7
    Electronic Resource
    Electronic Resource
    A simple and efficient mixed harmonic element for shells of revolution (1997)
    Chichester : Wiley-Blackwell
    Communications in Numerical Methods in Engineering 13 (1997), S. 565-572 
    Details
    ISSN: 1069-8299
    Keywords: mixed harmonic element ; shells of revolution ; consistent stress parameters ; Engineering ; Numerical Methods and Modeling
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: A simple and efficient three-noded mixed harmonic axisymmetric element for shells of revolution under non-symmetric loading is developed. The present element considering shear strain is based on a modified mixed variational principle in which the independent unknowns are only the quantities prescribable at the shell edges. The non-symmetric variations of the displacements and stress resultants in the circumferential direction are decomposed in terms of Fourier series. The stress resultants are eliminated on the element level so that the standard stiffness equations are obtained. The importance of consistent stress parameters is addressed and the efficiency of the present consistent mixed element is shown. © 1997 John Wiley & Sons, Ltd.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    A finite element formulation with stabilization matrix for geometrically non-linear shells (1992)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 33 (1992), S. 1703-1720 
    Details
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: An assumed strain finite element formulation with a stabilization matrix is developed for analysis of geometrically non-linear problems of isotropic and laminated composite shells. The present formulation utilizes the degenerate solid shell concept and assumes an independent strain as well as displacement. The assumed independent strain field is divided into a lower order part and a higher order part. Subsequently, the lower order part is set equal to the displacement-dependent strain evaluated at the lower order integration points and the remaining higher order part leads to a stabilization matrix. The strains and the determinant of the Jacobian matrix are assumed to vary linearly in the thickness direction. This assumption allows analytical integration through thickness, independent of the number of plies. A nine-node element with a judiciously chosen set of higher order assumed strain field is developed. Numerical tests involving isotropic and composite shells undergoing large deflections demonstrate the validity of the present formulation.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nme.1620330810
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