Development of an embedded solar tracker for the enhancement of solar energy utilization

An embedded two‐axis solar tracking system using Laboratory Virtual Instrumentation Engineering Workbench to write the operation and control algorithms was developed for enhancing solar energy utilization. The system consists of a real‐time processor, two motion‐control modules, two step drives, two step motors, feedback devices, and other accessories needed for functional stability. The real‐time processor allows the solar tracker to be used as a stand‐alone, real‐time system that can operate automatically without any external control. The system combines two different solar tracking methods: the optical method and the astronomical method. Cadmium Sulfide (CdS) sensors are employed to continuously generate feedback signals to the controller, ensuring high‐precision solar tracking even under adverse conditions. The CdS sensor is a resistor whose electric resistance decreases with increasing incident light intensity. A database of solar altitude, azimuth, and sunrise and sunset times is provided by this solar tracking system. Other solar trackers operating in an astronomical method may access and use this database over the Internet. Solar position and sunrise and sunset times in the database were compared with those of the Astronomical Applications Department of the U.S. Naval Observatory. The differences were found to be negligible. Copyright © 2011 John Wiley & Sons, Ltd.     

Spacecraft relative rotation tracking without angular velocity measurements

We present a solution to the problem of tracking relative rotation in a leader-follower spacecraft formation using feedback from relative attitude only. The controller incorporates an approximate-differentiation filter to account for the unmeasured angular velocity. We show uniform practical asymptotic stability (UPAS) of the closed-loop system. For simplicity, we assume that the leader is controlled and that we know orbital perturbations; however, this assumption can be easily relaxed to boundedness without degrading the stability property. We also assume that angular velocities of spacecraft relative to an inertial frame are bounded. Simulation results of a leader-follower spacecraft formation using the proposed controller structure are also presented.     

Stochastic dynamic output feedback stabilization of uncertain stochastic state-delayed systems

This paper addresses the problem of stochastic dynamic output feedback (SDOF) stabilization for a class of stochastic continuous-time state-delayed systems with norm-bounded nonlinear uncertainties. The aim is to design a linear, delayless, and SDOF control for all admissible uncertainties. The designed control ensures stochastically exponentially stability in the mean square, independent of the deterministic time delay. Using the Finsler's lemma, the necessary and sufficient conditions for the existence of such a control are proposed in terms of certain linear matrix inequalities. These results are illustrated with a simple example to demonstrate the applicability of the proposed design approach.     

一种基于平衡变压器的单相/三相供电方法

提出了一种新的基于Y/＞/D型平衡变压器的单相变三相供电方法.其原理是将单相电源分成并联的两条支路:一条直接接入平衡变压器一次侧α相,另一条经变流器移相成与之正交的β相,使其符合平衡变压器两相变三相的平衡变换条件,从而在二次侧获得三相对称电压.与单相变三相变流器相比,在同等负载条件下,该方法的变流器部分只需承受总负载的一半,因而更经济.最后,仿真实验证明了该方法的可行性和实用性.     

直线二级倒立摆的状态反馈实时控制

针对直线二级倒立摆系统的单输入三输出、强非线性、强耦合的不稳定系统,提出了状态反馈控制方案。通过仿真试验和实时控制实验验证了所提出的控制方案是可行的、有效的。分析和对比实验结果表明：配置的极点离原点越远,倒立摆在短时间内达到动态平衡的可能性就越大,而且配置的极点离实轴越近,控制效果就越好。     

一种实信号偶型排列信道化IFM接收机

在输入为实信号、滤波器组为偶型排列并且50%重叠的情况下,推导出多相滤波信道化接收机的高效结构,利用Hilbert变换将0信道的实数信号变为复解析信号,然后进行CORDIC算法测相、一阶差分算法测频。通过仿真实验证明该设计方案的正确性与可行性。     

微探针电化学加工机理及针尖尺寸控制技术

研究了电化学腐蚀法加工微探针的机理,建立了微探针成形的理论模型,提出实时控制加工微探针针尖曲率半径的新方法,发展了相应的控制加工技术。     

电信运营商基于大数据的业务模式分析

随着4G网络的大规模商用,移动互联网、物联网蓬勃发展,人们的行为、位置、甚至身体生理数据等每一点变化都成为了可被记录和分析的数据,这使电信运营商面临着不小的机遇和挑战。在综述大数据时代电信运营商所面临的主要机遇的基础上,分析了电信运营商在大数据应用方面的相对优势,介绍了数据挖掘及平台架构,探讨了电信运营商基于大数据的业务模式,以推进相关技术和应用,提升客户感知,支撑流量经营。     

Robust output feedback stabilization via a small gain theorem

In this paper, we give sufficient conditions for designing robust globally stabilizing controllers for a class of uncertain systems, consisting of ‘nominal’ nonlinear minimum phase systems perturbed by uncertainties which may affect the equilibrium point of the nominal system (‘biased’ systems). The constructive proof combines a systematic step-by-step procedure, based on H_∞ arguments, with a small gain theorem, recently proved for nonliner systems. At each step, one finds two Lyapunov functions, one for a state-feedback problem and the other one for an output injection problem. Combining these two functions, one derives at each step a Lyapunov function candidate for solving an ouptut feedback stabilization problem. This approach allows one to put into a unified framework many existing results on robust output feedback stabilization. © 1998 John Wiley & Sons, Ltd.     

Robust decentralized actuator fault detection and estimation for large-scale systems using a sliding mode observer

In this paper, robust decentralized actuator fault detection and estimation is considered for a class of non-linear large-scale systems. A sliding mode observer is proposed together with an appropriate coordinate transformation to find the sliding mode dynamics. Then, based on the features of the observer, a decentralized fault estimation strategy is proposed using an equivalent output error injection, and a decentralized reconstruction scheme follows by further exploiting the structure of the uncertainty which is allowed to have non-linear bounds. The estimation and reconstruction signals only depend on the available measured information and thus the proposed strategy can work on-line. The theoretical results which have been obtained are applied to an automated highway system. Simulation shows the feasibility and effectiveness of the proposed scheme.