Attitude control of spacecraft simulator without angular velocity measurement

In this paper the attitude control of a spacecraft simulator using Reaction Wheels (RW) as the actuators is investigated. The main goal of the current study is to bring the RWs to the rest at the end of the maneuver without angular velocity measurement. A modified feedback linearization controller is applied by considering the Euler angles of the simulator as the output and the RWs angular momentums as the internal state variables. The stability of the proposed controller and the internal dynamics is analyzed using Lyapunov theory. Two modified sliding mode observers are designed to estimate the angular velocities of the spacecraft attitude control subsystem simulator. The proposed observers do not use the control input and the detailed knowledge of the model and thus it can be implemented easily. The global stability of the system is proved. The proposed controller and observers are finally evaluated numerically and experimentally on an attitude spacecraft simulator.     

Diagnostic of fuel cell air supply subsystems based on pressure signal records and statistical pattern recognition approach

A data-driven and application-oriented diagnosis tool is developed for Fuel Cell (FC) air supply subsystems. A bench emulating a FC air line is built to study normal and abnormal operations (clogged inlet, air leakage, error in compressor speed control) and data are collected using the air pressure transducer, which is usually implemented in FC generators. A pattern recognition approach is then applied to statistical features extracted from the pressure signal. The performance of the diagnosis strategy is evaluated from confusion matrices, associated to graphs and performance indicators. Two examples of compressors, air subsystem managements, and data records are considered to examine the method portability. Best classification rates (>95%) are obtained on test profiles, when the pressure regulation is disabled; fault stamps can thus be found in the pressure signal morphology. Regarding the frequency of data logging, both 1 kHz and 100 Hz values are found effective for fault isolations.     

Uncertainty analysis and robust control of fuel delivery systems considering nitrogen crossover phenomenon

In this paper, the fuel delivery subsystem (FDS) with hydrogen recirculation and anode bleeding is applied in proton exchange membrane fuel cell (PEMFC) system, which is utilized to supply hydrogen to the anode of stack and recirculate fuel back to the supply line. As the diffusion of nitrogen from cathode to anode is inevitable in a real PEMFC during long-term operation. To prevent system performance decline due to nitrogen accumulation. Therefore, this paper firstly develops a control-oriented nonlinear dynamic FDS model involving gas diffusion. Additionally, the FDS is very sensitive to operating environment, uncontrolled operation conditions may cause stack degradation. Specifically, a method based on Monte Carlo simulation is proposed to identify the key parameter boundaries. Then the gas distribution in FDS due to nitrogen crossover is analyzed in detail. After this, a hybrid robust methodology based on sliding mode algorithm is also proposed to maintain adequate hydrogen pressure supply, suitable hydrogen and nitrogen content in the system in presence of nitrogen crossover and renewed uncertainties. Finally, the performance of the presented controller is compared with nonlinear PID (NPID) control and nonlinear multi-input-multi-output (NMIMO) control through a hardware-in-the-loop test bench. Experimental results show that the hybrid controller is accurate and suitable for control purpose, the nitrogen content is restricted to the given range and the variation of output voltage is limited to the desired boundaries, the feasibility and effectiveness are validated.     

五台坪上泉岩溶水系统划分研究

以山西省五台坪上泉岩溶水系统为例，介绍了岩溶水系统的概况，并对甲子湾泉、大湾泉、水泉弯泉等岩溶水系统作了明确划分，提出了岩溶水各亚系统间的相互关系。     

IBM ACS布线系统功能及优势

IBM ACS系统是一套主要面向计算机网络和电话系统的综合布线系统，它向用户提供了完整的、高质量的布线结构，ACS系统具有很强的适应性、扩展性、可靠性和长远效益。从计算机网络系统的角度出发，结合了电话系统的特点，研究了工程施工的具体情况，使综合布线系统满足计算机和电话系统的实用和美观要求。     

空间电源系统放电调节器技术的应用研究

结合我国空间电源系统放电调节器技术的发展现状,介绍了几种常用的蓄电池放电调节器的工作原理,给出了每种电路拓扑的工作电流波形,分析了每种电路拓扑的优缺点和应用场合,并对空间电源系统放电调节器技术的发展趋势进行分析和总结。     

刍议炸药库安防系统的设置

介绍了炸药的分类及其主要特点,从综合管理平台、入侵报警系统、视频监控系统、出入口控制系统等方面入手,详细阐述了炸药库安防系统的设置要求,指出了目前安防系统设置存在的主要问题,提出了解决问题的对策。     

微波输能技术的研究进展及发展趋势分析

微波输能技术(MPT)是实现远距离能量无线传输的主要方式之一,也是空间太阳能电站系统的核心技术之一.本文主要介绍了微波输能技术的国内外研究现状,并对微波输能技术的系统组成与关键技术做了分析,其中主要针对微波发射子系统与微波接收子系统两大模块进行了详细的讨论.最后,对微波输能系统技术所存在的问题以及未来发展的趋势进行了概括.     

基于CANopen的风源子系统通信研究

由于低速磁悬浮列车的广阔应用前景,对低速磁悬浮列车进行了介绍,并针对低速磁悬浮列车的通信要求提出了CAN总线。对CAN总线的技术特点进行了全面介绍,根据列车的特点引入了CAN的高层协议CANopen。通过对CANopen协议的剖析,说明此协议在低速磁悬浮列车上应用的优势。最后以低速磁悬浮列车空压系统中的风源子系统为例,对基于CANopen协议的列车通信进行了研究。