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61.
We address the problem of inverse dynamics for flexible multibodies, which arises, in trajectory tracking control of flexible multibodies such as space manipulators and articulated flexible structures. Previous research has resolved this trajectory tracking problem by computing the system inputs for feedforward control of actuators at the joints. Recently, the use of distributed actuators like electro-strictive actuators in flexible structures has introduced a new dimension to this trajectory tracking problem. In this paper we optimally utilize such actuators to aid joint actuators for tracking control, and introduce a new inverse dynamics scheme for simultaneously (1) tracking a prescribed trajectory and (2) minimizing ensuing elastic deflections. We apply this scheme for trajectory tracking of a two-link two-joint planar manipulator with joint motors and distributed electro-strictive actuators. Experimental results are presented to contrast our new scheme with other existing methods. 相似文献
62.
Surface functionalization of the plasma‐pretreated polycarbonate (PC) track‐etched membranes via plasma‐induced thermally graft copolymerization of acrylic acid (AAc) was carried out. The resulting PC membranes with grafted AAc side chains were characterized by X‐ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR) spectroscopy, and thermogravimetric (TG) analysis. The morphology of the PC membranes was studied by scanning electron microscopy (SEM). The results showed that the grafted PAAc polymers were formed uniformly inside the pores throughout the entire membrane thickness. With increase in the pore‐filling ratio, the pore diameters of PAAc‐grafted membranes became smaller. The PC‐g‐PAAc membranes exhibit rapid and reversible response of the flux to the environmental pH as pH is switched between 3 and 9. Between pH 3.5 and 5.5, the membranes demonstrate a pH‐valve function as the carboxyl group changes from neutral to charged with a corresponding variation in chain configuration. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
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64.
两轴光电跟踪仪高仰角跟踪盲区分析 总被引:1,自引:0,他引:1
从轴准直误差、动态滞后误差两方面分析了采用俯仰轴叠加于方位轴光机座结构方式的光电跟踪仪在高俯仰角跟踪时的误差变化及由此导致的盲区问题,从轴准直误差和动态滞后误差两方面对高仰角跟踪盲区的形成及其空间分布进行分析,并用MATLAB进行了仿真,给出跟踪盲区随方位、俯仰角变化的的分布图形。从盲区分布图形可以看出:光电跟踪仪在性能一定的情况下,跟踪盲区随着仰角增大而增大,并结合直线航路给出这两种误差导致的跟踪盲区的计算方法。跟踪直线航路实验数据显示跟踪误差随着仰角增大而增大。 相似文献
65.
66.
I consider two cases where QCD string is described by an effective theory of long strings: the static potential and meson scattering amplitudes in the Regge regime. I show how they can be solved in the mean-field approximation, justified by the large number of space–time dimensions, and argue that it turns out to be exact. I compare contributions from QCD string and perturbative QCD and discuss experimental consequences for the scattering amplitudes. 相似文献
67.
Javad Sharifi 《Physics letters. A》2011,375(3):522-528
The quantum trajectory renders the optimal estimation of quantum state. It is a classical Itô stochastic differential equation. The Lyapunov global stabilization problem is solved for squeezed noise quantum trajectory. Lyapunov control stabilizes the quantum system toward one eigenstate. A two-level bistable quantum system is simulated as an example. 相似文献
68.
针对嫦娥三号软着陆轨道设计与控制策略问题,在合理假设的前提下,建立动力学模型,求解得到了嫦娥三号着陆准备轨道近月点和远月点的速度。针对软着陆过程的6个阶段,通过受力分析,建立了嫦娥三号运动的微分方程模型,以燃料消耗最小为优化目标,以每个阶段的起止状态为约束条件,将软着陆轨道的优化设计问题转化为主发动机推力的泛函极值问题,并将其控制函数转化为近似的多项式函数优化问题。运用四阶Runge-Kutta差分迭代方法进行求解计算,从而得到各个阶段的最优控制函数和控制策略。结果表明,嫦娥三号软着陆过程耗时695s,消耗燃料1 269.1kg。 相似文献
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70.
J. Valenta V. Bradnováa V. Kohlováa F. Jukl S. I. Kulikova N. M. Nevzorova 《辐射效应与固体损伤》2013,168(4):333-336
Abstract Solid-state nuclear track detectors, made of Cd doped AgCl crystals, are commonly prepared by rolling into the form of thin foils. Subsequent long-term relaxation is however needed to obtain good quality tracks. The present communication shows for the first time that this detector “ageing” is reflected in lowtemperature (77 K) luminescence spectra. Maximum of the emission band shows a slow (lasting for ~ 100 hours) blue shift, the magnitude of which (as much as 25 nm) depends on the compression ratio caused by the rolling. The shift is believed to be due to the rearrangement of Cd++ ions around freshly introduced dislocations. This finding opens the possibility of monitoring non-destructively the process of detector ageing and to determine the minimum time required for saturation. 相似文献