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991.
Jürgen Appell 《Journal of Mathematical Analysis and Applications》2007,332(2):1134-1147
Using a continuation theorem for contractions, the existence, uniqueness, and an approximation method for a class of nonlinear boundary value problems on an unbounded interval is obtained. The results apply in particular to the problem in the title. 相似文献
992.
The purpose of this work is to investigate the weakened Ambrosetti–Prodi type multiplicity results for weak doubly periodic solutions of damped beam equations. By using the topological degree theory, the author obtains a result which is similar to the result for damped wave equations in the literature. 相似文献
993.
Fule Li Kaimei Huang 《高等学校计算数学学报(英文版)》2007,16(3):233-252
In this paper,the numerical approximation of a Timoshenko beam with bound- ary feedback is considered.We derived a linearized three-level difference scheme on uniform meshes by the method of reduction of order for a Timoshenko beam with boundary feedback.It is proved that the scheme is uniquely solvable,unconditionally stable and second order convergent in L_∞norm by using the discrete energy method. A numerical example is presented to verify the theoretical results. 相似文献
994.
Leaky wave characteristics of modified NRD (Nonradiative Dielectric) guide with parallel plate length are systemically investigated. A technique is used to investigate the leaky property of the guide structure, whichis formulated by effectively combining the multimode network theory with the mode-matching method. In the paper, two phenomena are carefully studied: First, the asymmetric position of the dielectric rod generates a leaky hybrid mode that could produce cross talk between components of the circuit. Second, when the length of metallic plate is finite, another type of leaky mode creates which influences and even couples to the normal leaky guide mode under appropriate circumstances. 相似文献
995.
Using weighted discretization with the modified equivalent partial differential equation approach, several accurate finite difference methods are developed to solve the two-dimensional advection–diffusion equation following the success of its application to the one-dimensional case. These new methods are compared with the conventional finite difference methods in terms of stability and accuracy. The new methods are more accurate and often more stable than the conventional schemes. 相似文献
996.
997.
Based on the Collins formula and irradiance moments definition, the propagation of the kurtosis parameter of super-Gaussian beams through a spherically aberrated lens is studied. Detailed numerical results are given. It is shown that, as compared with aberration-free super-Gaussian beams, the profile of spherically aberrated super-Gaussian beams can be leptokurtic, mesokurtic or platykurtic, depending on the aberration and propagation distance. The results for the spherically aberrated Gaussian beams can be dealt with as a special case treated in this paper. Finally, the advantage of our method is pointed out. 相似文献
998.
综述了暗中空光束自旋与轨道角动量的一些性质及其与中性原子之间的相互作用,并简单介绍了暗中空光束及其角动量在原子光学和玻色_爱因斯坦凝聚(BEC)以及各种原子光学器件研制方面的应用. 相似文献
999.
P K Chakraborti 《Pramana》1978,11(3):307-311
By means of refinements in the modulated molecular beam technique the signal-to-noise ratio can be greatly improved, and differential
cross-sections, for collision of molecuies of the same species, can be measured. This was accomplished by combining beam modulation
and phase sensitive detection with very sharp turning on the front end of the lock-in-amplifier and long integration times
on the output. In addition, the signal-to-noise ratio of the Ar-Ar system as a function of integration time was investigated
using two different types of electron bombardment detectors an Aberth ion-source and a quadrupole mass filter. With an integration
time of 40 min the estimated upper limit to the signal-to-noise ratio is 1500 to 1 for the Aberth ion-source. Using quadrupole
mass filter with an integration time of 60 min the estimated upper limit to the signal-to-noise ratio is 5 × 104 to 1. For chemical kinetics studies this ratio may be two orders of magnitude higher.
Measurements were carried out at the Purdue University, Lafayette, Indiana, USA. 相似文献
1000.
We have measured time-of-flight (TOF) distributions of Br atoms desorbed from thin (less than 1000 Å) epitaxial films of KBr on (100) InSb with a 2 keV electron beam. Although the general structure of the TOF spectra was similar to that obtained previously for the thick crystals, both the fast and the slow (thermal) components of the distribution were strongly dependent on the film thickness. We argue that this dependence is due to two different diffusion processes involved in the transport of the primary excitation products from the bulk to the surface. By measuring the velocity resolved ESD yield for films of various thicknesses, we determined that a diffusion length of the carriers responsible for the thermal ESD component varied from 30 to 700 Å with temperature in the range 20–300°C. In contrast, for the non-thermal desorption we found the carrier diffusion length of about 140 Å which did not depend significantly on the temperature. 相似文献