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971.
972.
The system considered is a generalized system E
= Ax + Bu, Y = Cx with matrix E singular. When the impulsive modes of the system are both controllable and observable, it is shown in this paper that these modes can be eliminated by almost any constant output feedback. For a strongly controllable and observable generalized system, after its impulsive modes are eliminated, the poles of the system can be assigned arbitrarily by state feedback. Even if the states are not available, the paper adopts an efficient method to design a compensator for the system. 相似文献
973.
974.
兆瓦级同步风力发电机变桨距控制策略研究 总被引:2,自引:2,他引:2
变桨距风力发电机已成为风力发电机组的主要研究和发展方向,结合长星集团同步风力发电机组,对变桨距控制技术进行了研究,在额定风速以下时实行变速运行,控制发电机的励磁电流从而控制发电机的转速,使得风力机转速能够跟随风速变化,保持最佳叶尖速比使系统获得最大的风能利用系数;额定风速以上时,采用PID控制算法控制桨距角,使发电机输出功率恒定,并提出了实现方法;通过仿真工具进行计算机仿真,验证了本方法的有效性。 相似文献
975.
张贵川 《河北建筑工程学院学报》2008,26(2):74-75
合理的户型设计将成为未来住宅市场上的核心竞争力.通过分析当前张家口住宅产业发展现状和市场需求,提出了进行中小套型住宅的开发策略. 相似文献
976.
张贵川 《河北建筑工程学院学报》2008,26(2):90-91
随着城市化进程的加快,旧城改造力度也随之加大.结合张家口的古建筑特征,探讨了进行古建筑保护的原则. 相似文献
977.
Lower bounds on lengths of checking sequences 总被引:1,自引:0,他引:1
Guy-Vincent Jourdan Hasan Ural Hüsnü Yenigün Ji Chao Zhang 《Formal Aspects of Computing》2010,22(6):667-679
Lower bounds on the lengths of checking sequences constructed for testing from Finite State Machine-based specifications are
established. These bounds consider the case where a distinguishing sequence is used in forming state recognition and transition
verification subsequences and identify the effects of overlapping among such subsequences. Empirical results show that the
existing methods for construction of checking sequences provide checking sequences with lengths that are within acceptable
distance to these lower bounds. 相似文献
978.
979.
Research on planar-to-stereo image conversion has significant theoretical and practical implications for image processing. In this paper we use a method which segments an image into sub-blocks to perform this kind of conversion; parameters such as random variables are used for conversion control. We use two quantitative criteria, cross-entropy and root-mean-square error, to evaluate the stereo effect. Furthermore, the stereo effect that the random variables create is discussed. The results of the experiment show that, (i) when all random variables have the same distribution, different values of these random variables only slightly affect the stereo effect; and (ii) when different distributions are applied to the random variables, the cross-entropies or root-mean-square errors are slightly different, which indicates different distributions have a small influence on the stereo effect. Generally, we recommend normal distribution for better stereo effect in most cases. 相似文献
980.
Kaizhi Zhang Haidong Yu Zhongpo Liu Xinmin Lai 《Simulation Modelling Practice and Theory》2010,18(7):1019-1031
In this paper, by taking into account the periodically varying mesh stiffness in multiple pinions transmission and the speed–torque characteristics of variable frequency motor drives, the dynamic model for the revolving system of tunnel boring machine (TBM) has been established. Based on the soft ground/hard rock assumption of mixed-face conditions and the analysis of cutting force on each disc cutter and each drag bit, the time-varying excavation torque on the TBM cutterhead in mixed-face tunnelling is obtained. The dynamic excavation torque and cutterhead rotation speed are discussed and compared for TBM tunnelling in several typical mixed-face conditions, which are characterized by the area percentage of soft ground on the excavation face and the uniaxial compressive strength (UCS) of rock. The results show that the excavation torque may run up to a critical value and fluctuate greatly in extremely adverse excavation environments, which may lead to an unexpected TBM stoppage and even a catastrophic failure of the drive motor. To decrease the penetration per revolution in time through applying a lower advance velocity and a higher cutterhead revolution will significantly reduce the excavation torque and effectively avoid such situations. 相似文献