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131.
In this paper, we are concerned with the partial regularity for suitable weak solutions of the tri-dimensional magnetohydrodynamic equations. With the help of the De Giorgi iteration method, we obtain the results proved by He and Xin (C. He, Z. Xin, Partial regularity of suitable weak solutions to the incompressible magnetohydrodynamic equations, J. Funct. Anal. 227 (2005) 113–152), namely, the one dimensional parabolic Hausdorff measure of the possible singular points of the velocity field and the magnetic field is zero. 相似文献
132.
133.
A.W. Bett F. Dimroth G. Stollwerck O.V. Sulima 《Applied Physics A: Materials Science & Processing》1999,69(2):119-129
Research activities in the field of III-V solar cells are reviewed. III-V compound semiconductors are used for space solar
cells, concentrator solar cells, and in thermophotovoltaic generators. The epitaxial growth of ternary and quaternary material
by MOVPE and LPE allows us to realize various band gaps. Multi-junction solar cells with different band gaps are necessary
to obtain efficiencies larger than 30%. Recent results of the III-V solar cell research at the Fraunhofer ISE are presented.
A mechanically stacked GaAs/GaSb tandem concentrator solar cell achieved an efficiency of 31.1% under 100×AM1.5d. An efficiency
of 23% for a two-terminal concentrator module (486 cm2) with Fresnel lenses has been measured under realistic outdoor conditions.
Received: 1 March 1999 / Accepted: 28 March 1999 / Published online: 24 June 1999 相似文献
134.
Pawe? Szabelski 《Applied Surface Science》2010,256(17):5503-539
The Monte Carlo simulation method was used to model thermal desorption of a pair of enantiomers from a solid surface with a chiral periodic pattern of active sites. The main objective of the study was to determine the optimal number of the active sites and their spatial distribution within the unit cell of the surface to achieve the most efficient separation of the enantiomers. For that purpose we tested the series of chiral patterns which were found previously for the equilibrium adsorption. Temperature programmed desorption spectra were calculated using a square lattice of adsorption sites in which the active sites were distributed spatially according to the candidate patterns. Additionally, influence of relaxation of the adsorbed layer on the relative shift of the TPD peaks of the enantiomers was assessed and the key factors affecting the chiral separation were identified. 相似文献
135.
Claudio Rebbi 《Journal of statistical physics》1986,43(5-6):1117-1127
Some recent Monte Carlo calculations for quantum chromodynamics, performed on Euclidean lattices of rather large extent, are
reviewed. The purpose of the calculations is to provide accurate determinations of quantities, such as interquark potentials
or mass eigenvalues, which are relevant for hadronic spectroscopy. Results obtained in quenched QCD on 163×32 lattices are illustrated, and a discussion of computational resources and techniques required for the calculations is
presented. 相似文献
136.
Interband transitions in GaNyAs1−y/GaAs multi quantum well (MQW) samples with y=0.012 and 0.023 have been studied by contactless electroreflectance spectroscopy (CER). Optical transitions related to absorption in the GaAs barriers and in the GaNyAs1−y/GaAs QWs have been observed and analyzed. The GaAs related transition exhibits clear Franz-Keldysh oscillations with the period corresponding to the built-in electric field of 14 and 17 kV/cm for samples with y=0.012 and 0.023, respectively. The portion of the CER spectrum related to absorption in the GaNyAs1−y/GaAs QW exhibits two clear resonances which are attributed to optical transitions between the ground and excited states confined in the QWs. The resonance attributed to the ground state transition is associated with absorption between the first light- and heavy-hole subbands and the first electron subband (11L and 11H) while the resonance attributed to the excited state transition is associated with absorption between the second heavy-hole subband and the second electron subband (22H). The energies of the 11H and 22H transitions have been matched with those obtained from theoretical calculations performed within the effective mass approximation. Thus, the GaNyAs1−y/GaAs QWs are type-I structures with a conduction band offset, QC, between 70 and 80%. Moreover, the incorporation of N atoms into GaAs is found to cause a significant increase in the electron effective mass. The determined values of electron effective mass for GaNyAs1−y/GaAs QW with y=0.012 and 0.023 are 0.105m0 and 0.115m0, respectively. 相似文献
137.
Giant magnetoresistance (GMR) of sequentially evaporated Fe-Ag structures has been investigated. Direct experimental evidence is given, showing that inserting ferromagnetic layers into a granular structure significantly enhances the magnetoresistance. The increase in the GMR effect is attributed to spin polarization effects. The large enhancement (up to more than a fourfold value) and the linear variation of the GMR in low magnetic fields are explained by scattering of the spin polarized conduction electrons on paramagnetic grains. 相似文献
138.
Huan-You Wang Hui Xu Tie-Tie Huang Chao-Sheng Deng 《The European Physical Journal B - Condensed Matter and Complex Systems》2008,62(1):39-43
The density function perturbation theory (DFPT) is employed to study
the linear thermal expansion and heat capacity at constant pressure
(with the quasiharmonic approximation) for wurtzite GaN. The
calculated results of linear thermal expansion coefficient and heat
capacity at constant pressure are compared with the available
experimental data in a wide temperature range. Generally these
properties calculated agree well with experimental data except at
high temperature, thus it suggests the thermal expansion and heat
capacity can be well calculated from this first-principle approach. 相似文献
139.
Akhlesh Lakhtakia 《Optik》2006,117(4):188-192
When a (frequency-domain) boundary-value problem involving a homogeneous linear material is solved to assess the validity of the Post constraint, a conflict arises between the fundamental differential equations of electromagnetism in the chosen material and a naïve application of the usual boundary conditions. It is shown here that the conflict vanishes when the boundary conditions are properly derived from the fundamental equations, and the validity of the Post constraint in modern macroscopic electromagnetism is thereby reaffirmed. 相似文献
140.
O. Rubel S.D. Baranovskii K. Hantke B. Kunert W.W. Rühle P. Thomas K. Volz W. Stolz 《Journal of luminescence》2007,127(2):285-290
An overview of recent experimental and theoretical results on stationary and time-dependent photoluminescence spectra in disordered semiconductor heterostructures is presented. In particular, temperature-dependent peak position and linewidth of the luminescence spectra, as well as the luminescence intensity are considered along with the time evolution of the luminescence intensity after pulsed excitation. Emphasis is given on the comparison between experimental and theoretical results aiming at a characterization of disorder in the underlying structures. 相似文献