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991.
992.
一类非线性方程组的奇摄动问题 总被引:20,自引:1,他引:19
本文在较弱的假设下.用校正边界层的方法得到了一类非线性奇摄动方程组的一致有效渐近展开式.并得到了其渐近性态. 相似文献
993.
994.
阐明了3ω方法的机理,并在此基础上讨论了它的一些基本应用.利用3ω方法可以对具有优 良导热和导电能力的材料的热导率和热容进行测量;对不能导电的材料,固态的或液态的, 利用3ω方法能对它们的热导率进行测量.对测量中涉及到的热辐射问题的讨论表明,由于使 用的是小样品,热辐射造成的影响可以忽视.通过理论推导,使用二维隧穿结点阵并借助3ω 方法,可以给出一种性能良好的二维库仑阻塞测温法.
关键词:
3ω方法
热容(定压)
热导率
库仑阻塞 相似文献
995.
KMnF3 and DKDP crystals have been studied around their phase transitions using a conduction calorimetry technique where a long periodical square thermal pulse (0.05 K in amplitude) is superposed to a heating or cooling ramp as low as 0.06 K h−1. Specific heat data obtained in the dissipation and relaxation semiperiods of the square pulse become different inside the phase transition interval. The electromotive force developed by the heat fluxmeters at the end of the relaxation semiperiod (underlying signal) is compared with the DTA trace obtained in a second run with the same temperature ramp but without the modulated perturbation. The comparison between the DTA trace and specific heat data obtained in the first run allows us to determine the value of the latent heat and to obtain information about the kinetic of the phase transition. 相似文献
996.
Y.M. Park Y.J. Park K.M. Kim J.I. Lee K.H. Yoo 《Physica E: Low-dimensional Systems and Nanostructures》2005,25(4):647-653
We have investigated the optical properties of InAs self-assembled quantum dots (SAQDs) with the Si-doped GaAs barrier layer. Two types of samples are fabricated according to the position of the Si-doped GaAs layer. For type A samples the Si-doped GaAs layer is grown below the QDs, whereas for type B samples the Si-doped GaAs layer is grown above the QDs. For both types of samples the excited-state emissions caused by state filling are observed in photoluminescence (PL) spectra at high excitation power densities. The bandgap renormalization of QDs can be found from the shift of the PL peak energy. Particularly, for type A samples the Si atoms act as nucleation centers during the growth of InAs QDs on the Si-doped GaAs layer and affect the density and the size of the QDs. The Si-doped GaAs layer in type A samples has more effects on the properties of QDs, such as state filling and bandgap renormalization than those of type B samples. 相似文献
997.
基于神经网络的钞票真假识别研究 总被引:3,自引:1,他引:2
利用神经网络与光电检测的技术研制了钞票真假识别系统.介绍了系统的结构组成、工作原理、软件系统、神经网络的优化设计、实验及测试结果.经实践验证,其识别结果稳定可靠,可应用于金融智能防伪点钞机与ATM机中. 相似文献
998.
999.
In this Note, we present direct numerical simulation results of a spatial mixing layer generated behind an upstream plate separating two boundary layers. The effect of the shape of the trailing edge of the plate is considered through comparisons between flows obtained from a bevelled or a blunt plate. In the former case, a spatial mixing layer consistent with previous experimental and numerical observations is obtained. In the latter case, the self-excited state that establishes in the near wake region dominates primary and secondary instability mechanisms while understating the importance of inflow perturbations. This behaviour is interpreted in terms of convective or absolute instability. The effects on turbulent statistics are also discussed. To cite this article: S. Laizet, E. Lamballais, C. R. Mecanique 334 (2006). 相似文献
1000.
V. I. Fabrikant 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》2006,57(3):464-490
The contact problem for an arbitrary punch acting on a transversely isotropic elastic layer bonded to a rigid foundation is
solved by the generalized images method developed by the author earlier. The problem is reduced to that of an electrostatic
problem of infinite row of coaxial charged disks in the shape of the domain of contact. The solution can be obtained by the
method of iteration, collocations or any other standard procedure for solving integral equations. Exact inversion can be obtained
in the case of a circular domain of contact. The mean value theorem can be used for estimation of the resultant force and
tilting moment acting on a punch of arbitrary shape and circular domain of contact. A limiting case of general solution gives
the solution for an isotropic layer.
(Received: August 11, 2003) 相似文献