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1.
有限转角无刷力矩电动机位置伺服系统的电流控制 总被引:3,自引:0,他引:3
提出了有限转角无刷力矩电动机 (LABLTM)位置伺服系统电流控制策略 ,给出了实施方法 ,进行了开关管频率特性的分析。该方法可实现在不同误差时自动调节电动机电流 ,进而控制输出转矩 ,并具有稳态精度高、动态响应快等特点。 相似文献
2.
3.
提出用测量光纤偏振耦合率来确定模耦合系数,从而得到耦合微扰功率谱与双折射关系。它给出了光纤拉制中微扰作用 的信息,是研制偏振光纤的一种有效方法。 相似文献
4.
L. Pamela Cook Emeka Nwankwo Gilberto Schleiniger Bryan Wood 《Journal of Engineering Mathematics》2003,45(3-4):269-282
A general formulation for capillary flow of two miscible fluids – one a dilute plug of polymer fluid inserted into a fully developed Poiseuille flow of the other, a Newtonian stream – is examined for its long time behavior. Phenomenologically, the system evolves from an initial state, that of a plug within the boundaries of sharp, well defined fronts inside a Newtonian stream, to a more homogenized state in the very long time scale. This problem was addressed by G.I. Taylor but with regard to a system of two Newtonian fluids, leading to the well-known results commonly described as `Taylor axial dispersion'. In this paper, a general and systematic perturbation analysis is presented from which Taylor's result is recovered as a special case of a more general solution which applies to fluids incorporating elastic properties. In particular, the influence of viscoelasticity and (polymer) diffusivity on the observed pressure profile in the capillary conduit is examined. This effect is clearly separated out for small Peclet number flows using asymptotic and numerical analysis. The results identify the influence of fluid viscosity, elasticity, and diffusivity on the observed pressure profile and form the basis for the improved characterization of polymeric elasticity using capillaries – a finding that is of significant scientific and commercial interest. These results were obtained by the authors as a class of observations resulting from the perturbation analysis of forced-flow capillary devices in viscoelastic fluid property investigation. 相似文献
5.
Moshe Dayan 《Journal of Superconductivity and Novel Magnetism》2007,20(3):239-247
Here I establish the field perturbation theory of pseudogaps in HTSC. The proposed ground state suggests an internal particle-hole
field, which is normal to nesting surfaces, and having twice the Fermi wave number. It is proved that the system violates
momentum conservation by the wave vector of this internal field. This violation applies to the quasi-particle propagators,
as well as to the interactions. Interaction vertices via the Pauli matrix-τ1 are established. This, in turn, establishes the validity of the pseudogap Hartree self-energy. 相似文献
6.
层状介质中重力,地震联合反演的迭代算法 总被引:14,自引:2,他引:12
本文提出一种用于层状介质中重力、地震资料联合反演层速度、层密度及弯曲界面深度的迭代算法。该方法通过引入加权最小平方目标泛函,将层状介质中的重力、地震资料联合反演问题转化成具体的优化问题。为了得到反问题的最优解,文中系统地研究了层状介质中双摄动处理技术,以及层状介质中波场摄动的一阶 Born 近似解与理论重力异常摄动解。并应用 Tarantola 的反演理论,导出了梯度算子的计算公式。然后应用最速下降法给出了求取最优解的具体算法,得到了一种类似于地震偏移与空间更投影的迭代反演方法。对理论模型进行重力、地震联合反演的结果表明,该方法不仅可碱少未知参数的个数,提高反演的收敛速度,而且可减少反演的不适定性,不失为一种可行的多参数反演方法。 相似文献
7.
V. V. Semenov 《Cybernetics and Systems Analysis》2007,43(2):246-252
For infinitely dimensional convex vector maximization problems, it is proved that there exists, under certain conditions,
an arbitrarily small additive perturbation of the performance criterion by a linear continuous operator such that the perturbed
problem has efficient solutions.
The study was sponsored by the Ukrainian State Fund for Basic Research
__________
Translated from Kibernetika i Sistemnyi Analiz, No. 2, pp. 105–114, March–April 2007. 相似文献
8.
FMS的模型参考自适应调度 总被引:1,自引:0,他引:1
用运筹学研究生产线调度问题已有几十年的历史,但由此得出的调度策略的实时性很差.1986年自动控制工作者提出了“PMS动态自适应计算机调”一词.令人感到十分新奇.可惜.从未见到任何有关的论文.本文研究FMS的模型参考自适应调度.本文采用我们提出的考虑了有限缓冲器容量的极大代数模型.环境的影响反映于对象参数的摄动,本文采用我们提出的摄动计算方法.调度器的设计采用次梯度法,以求解连续变量和离散变量混合的优化问题,附有数字实例,计算和仿真表明:FMS的模型参考自适应调度是可行的,是值得继续深入研究的。 相似文献
9.
The specific heat at constant pressure, C
p, of aluminum measured by Ditmars, Plint, and Shukla has been reduced to the volume V
0 appropriate for 0 K employing the Murnaghan equation. The C
v0 thus obtained is compared with the theoretical C
v0 calculated in the harmonic and the lowest-order anharmonic approximation from three different pseudopotentials (Harrison, Ashcroft, and Dagens-Rasolt-Taylor) as well as a phenomenological Morse potential. The higher-order (
4) anharmonic contributions are calculated from the same nearest-neighbor Morse potential as in the lowest-order anharmonic theory. The role of the vacancy and the higher-order anharmonic contributions to C
v0 has been examined and we conclude that the
4 contributions to C
v0 are much smaller than the vacancy contribution. After removal of the vacancy contribution, the reduced C
v0 is found to be in excellent agreement with the Ashcroft and Harrison pseudopotentials as well as the Morse potential including the
2 and
4 contributions to C
v0. 相似文献
10.
M. Rahman 《化学,工程师,技术》1975,47(17):729-729