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951.
半球谐振子密度分布不均匀对输出精度的影响 总被引:1,自引:0,他引:1
为了研究半球谐振子环向密度分布不均匀对输出精度的影响,首先推导了位置激励表达式,利用解微分方程的布勃诺夫-加廖尔金法建立了谐振子环向密度分布不均匀的动力学方程,然后根据动力学方程并利用平均值法推导了含有密度四次谐波误差的短时间内的漂移模型,最后根据Runge-Kutta法对系统长时间漂移进行了仿真计算,通过计算可知当密度四次谐波幅值为0.0001 kg/m3时,角位置1h内的漂移达到0.03°,因此在加工工艺过程中密度四次谐波应小于此值或采用其他方式加以补偿. 相似文献
952.
韩友发 《数学物理学报(B辑英文版)》2011,31(3):1011-1019
The central subject of studying in this paper is incompressible pairwise incompressible surfaces in link complements. Let L be a non-split prime link and let F be an incompressible pairwise incompressible surface in S~3 - L. We discuss the properties that the surface F intersects with 2-spheres in S~3 - L. The intersection forms a topological graph consisting of a collection of circles and saddle-shaped discs. We introduce topological graphs and their moves (R-move and S~2-move), and define the characteristic number of the topological graph for F∩S~2±. The characteristic number is unchanged under the moves. In fact, the number is exactly the Euler Characteristic number of the surface when a graph satisfies some conditions. By these ways, we characterize the properties of incompressible pairwise incompressible surfaces in alternating (or almost alternating) link complements. We prove that the genus of the surface equals zero if the component number of F∩S~2+(or F∩S~2-) is less than five and the graph is simple for alternating or almost alternating links. Furthermore, one can prove that the genus of the surface is zero if #(F) ≤8. 相似文献
953.
In this paper, boundedness and compactness of the composition operator on the generalized Lipschitz spaces Λα (α > 1) of holomorphic functions in the unit disk are characterized. 相似文献
954.
Let S be a finite set of points in the Euclidean plane. Let G be a geometric graph in the plane whose point set is S. The stretch factor of G is the maximum ratio, among all points p and q in S, of the length of the shortest path from p to q in G over the Euclidean distance |pq|. Keil and Gutwin in 1989 [11] proved that the stretch factor of the Delaunay triangulation of a set of points S in the plane is at most 2π/(3cos(π/6))≈2.42. Improving on this upper bound remains an intriguing open problem in computational geometry.In this paper we consider the special case when the points in S are in convex position. We prove that in this case the stretch factor of the Delaunay triangulation of S is at most ρ=2.33. 相似文献
955.
956.
957.
基于红边位置提取验证成像与非成像高光谱数据的一致性 总被引:1,自引:0,他引:1
定量遥感是当前遥感发展的前沿,作物组分信息解析是农业定量遥感的研究热点,而成像高光谱技术为解决微观尺度的作物组分信息探测研究提供了强有力的手段.利用成像光谱仪( pushbroom imaging spectrometer,PIS)与地物光谱仪(FieldSpec ProFR2500,ASD)同步收集冬小麦、玉米不同生... 相似文献
958.
M. G. Marmorino Kayleigh Cassella 《International journal of quantum chemistry》2011,111(14):3588-3596
A generalization of a method to calculate lower bounds to expectation values of non‐negative observables is presented. We consider bounds to three electronic expectation values 〈r2〉, 〈r〉, and 〈r?1〉 in the helium atom as an example. For both 〈r2〉 and 〈r〉, we are able to calculate improved lower bounds. The lower bound to 〈r?1〉 does not improve, but we are able to calculate an upper bound which is much closer to the expectation value than the lower bound. Although our generalization allows for improved bounds and/or upper bounds, these bounds to general observables are much less precise than energy bounds and even the expectation values calculated from variational wave functions. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2011 相似文献
959.
C-H Nitrooxylation at benzylic positions has been achieved by employing the N-hydroxyphthalimide (NHPI) catalyst/cerium(IV) ammonium nitrate (CAN) reagent system. The nitrooxy groups were demonstrated to function as tentative hydroxy protecting groups, as well as excellent leaving groups for N- and C-substitution reactions. Hence, the present method offers a unique way to synthesize diverse O-, N-, or C-functionalized benzylic compounds from simple alkyl aromatics. 相似文献
960.
The third harmonic generation (THG), linear and nonlinear optical absorption coefficients (OACs), and refractive index changes (RICs) are investigated in a Woods–Saxon quantum well (QW) modulated by the hydrostatic pressure and applied electric field. The effect of non-uniform aluminum doping (position-dependent effective mass (PDEM)) on the mass of the system is discussed, and further to explore the influence of PDEM on the nonlinear THG, OACs, and RICs of the Woods–Saxon QW. These nonlinear optical properties above are obtained using the compact-density matrix formalism. The electron states in a Woods–Saxon QW under the constant effective mass (CEM) and PDEM are calculated by solving the Schrödinger equation via the finite difference technique. The contributions from competing effects of the hydrostatic pressure and applied electric field to the nonlinear optical properties with CEM and PDEM are reported, as well as the comparison with each other. The observations reveal that the regulation of external fields and the influence of PDEM play an important role in the photoelectric properties of QW. 相似文献