惯性冲击对低真空封装的RF MEMS电容开关性能的影响

分析了外界惯性冲击对低真空封装的旁路电容式RF MEMS开关性能的影响.得到了近似计算外界惯性冲击引起位移的解析式.在已知最大容许插入损耗和外部惯性冲击环境条件下,MEMS开关支撑梁的最小机械刚度常数以及外部惯性冲击引起的插入损耗可以根据该式得到.通过RF MEMS电容式开关实例,表明设计低真空封装的RF MEMS电容式开关时应考虑外部环境因素.可见,RF MEMS开关用低真空封装可以减小空气阻尼、改善开关速度和执行电压的同时,开关的性能却容易受外界环境因素的影响.该研究对低真空封装的RF MEMS电容式开关的优化设计很有意义.     

MPE2S: 基于多路径纠删编码的无线传感器网络可靠传输策略

传输可靠性是衡量无线传感器(Wireless sensor networks, WSN)网络性能的一个重要指标. 针对节点故障会影响网络传输稳定性和可靠性的问题, 提出了基于多路径纠删编码的 无线传感器网络可靠传输策略(Multi-paths and erasure encoding strategy, MPE2S). 根据反映链路质量的最优最差蚂蚁系统的信息素归一化值, 在相邻等级节点间建立多条互不交叉的传输路径, 将源数据包经纠删编码的 数据片沿多条路径分配和传输以实现负载均衡和故障容错. 理论分析和仿真结果表明,MPE2S具有较高数据包接收率、数据准确率和能效性, 体现了良好的故障容错性、数据传输稳定性和可靠性.     

Robust reliable control for a near space vehicle with parametric uncertainties and actuator faults

Based on fuzzy control techniques, this article is concerned with the problem of robust reliable control for a near space vehicle (NSV) with parametric uncertainties and actuator faults. The nonlinear dynamics of a NSV is represented by the Takagi–Sugeno fuzzy models, and then the actuator fault model and fuzzy state-space observer are developed. Next, the fuzzy observer-based robust reliable control strategy is proposed. It is proved that the fuzzy control systems for the NSV is reliable in the sense that the closed-loop system is asymptotically stable and the actuator components can operate well in the presence of some actuator faults. The developed theoretical results are in the form of linear matrix inequalities, which can be readily solved via standard numerical software. Finally, simulation results are given to illustrate the applicability of the proposed approach.     

Delay-dependent reliable H ∞ filtering for sector-bounded nonlinear continuous-time systems with time-varying state delays and sensor failures

In this article, the reliable H _∞ filtering problem against sensor failures is investigated for a class of continuous-time systems with simultaneous sector-bounded nonlinearities and varying time delays. The focus of this article is on designing a reliable filter such that the filtering error system is asymptotically stable and meets the prescribed H _∞ norm constraint in the normal case as well as in the sensor failure case simultaneously. Linear matrix inequality conditions, which depend not only on the upper and lower bounds of delay but also on the upper bound of delay derivative, are obtained for the existence of admissible filters and, based on these, the filter design is cast into a convex optimisation problem. What is worth mentioning is that the information about the upper bound of the delay derivative is taken into consideration even if this upper bound is not smaller than 1. A numerical example is presented to illustrate the effectiveness and advantage of the developed filter design method.     

CORDIC Processor for Variable-Precision Interval Arithmetic

In this paper we present a specific CORDIC processor for variable-precision coordinates. This system allows us to specify the precision to perform the CORDIC operation, and control the accuracy of the result, in such a way that re-computation of inaccurate results can be carried out with higher precision. It permits a reliable and accurate evaluation of a wide range of elementary functions. The specific architecture designed greatly improves the computational time of previous solutions based on classic polynomial approximation. For controlling error in numerical computation (where intervals are normally narrow) the proposed design performs an interval operation in a time close to that of a point operation.     

有源RFID系统中可靠通信的研究

有源RFID是一种自动识别技术,在追踪和识别高价值商品方面具有突出优势。针对通信距离的增加,有源RFID系统出现识读不可靠、数据出错等问题。构建了基于CC2510的有源RFID系统,并结合硬件特性,重点对读写器与有源电子标签之间的通信数据帧标识、数据帧结构、标签防冲突处理和数据错误重传机制等方面进行探讨和设计。实验结果表明,改进后的通信机制对不同的测试环境具有一定的适应能力,表现出较好的可靠性。     

移动Ad hoc网络可靠多路径路由协议的综述

分析研究了移动Adhoc网络（MANET）的可靠多路径路由协议,可靠多路径路由协议的主要目标是提供可靠的通信、以确保负载平衡以及提高服务质量（QoS）。本文分析了Adhoc网络多路径路由技术的研究进展,论述了典型的Adhoc网络多路径路由协议性能,最后对Adhoc网络多路径路由的发展趋势进行了展望。     

Time-dependent vibration frequency reliability analysis of blade vibration of compressor wheel of turbocharger for vehicle application

Blade vibration failure is one of the main failure modes of compressor wheel of turbocharger for vehicle application. The existing models for evaluating the reliability of blade vibration of compressor wheel are static, and can not reflect the relationship between the reliability of compressor wheel with blade vibration failure mode and the life parameter. For the blade vibration failure mode of compressor wheel of turbocharger, the reliability evaluation method is studied. Taking a compressor wheel of turbocharger for vehicle application as an example, the blade vibration characteristics and how they change with the operating parameters of turbocharger are analyzed. The failure criterion for blade vibration mode of compressor wheel is built with the Campbell diagram, and taking the effect of the dispersity of blade natural vibration frequency and randomness of turbocharger operating speed into account, time-dependent reliability models of compressor wheel with blade vibration failure mode are derived, which embody the parameters of blade natural vibration frequency, turbocharger operating speed, the blade number of compressor wheel, life index and minimum number of resonance, etc. Finally, the rule governing the reliability and failure rate of compressor wheel and the method for determining the reliable life of compressor with blade vibration is presented. A method is proposed to evaluate the reliability of compressor wheel with blade vibration failure mode time-dependently.     

高压高转速服役特征下唇形油封失效机制

坦克车综合传动系统中油封经常处于高压、高转速的工况,出现短时失效泄漏且在工况条件降低后密封性能恢复。针对这一问题,以唇形油封的泵汲理论作为其失效评判标准,首先,通过分析不同介质压力下油封的变形特征和接触特性,发现油封受压后腰部向轴侧塌陷、唇部翘曲,导致其接触宽度增加、最大接触应力减小,不利于产生或失去泵汲效应;其次,基于高速下油封摩擦升温现象,指出转速增加使油封橡胶材料的弹性模量下降,导致油封的抵抗变形能力减弱,其受压时腰部变形量增大;最后,对高压高转速服役特征下的油封进行分析,发现转速作用下油封升温导致其腰部抵抗变形能力下降,同时施加介质压力后加剧其腰部的塌陷程度,降低其工作可靠性,进一步得出了油封的可靠介质压力与转速之间的匹配关系。研究成果可为设计优化耐高压高速油封及油封选型提供参考和理论支持。     

电动汽车充电桩/机校验仪国内技术现状及溯源研究

电动汽车交流充电桩校验仪、电动汽车直流充电机校验仪是电动汽车充电桩/机的计量标准器,其准确可靠可为强检计量器具电动汽车充电桩/机的量值提供保证。通过对国内电动汽车充电桩/机校验仪的长期全面测试和理论研究,较全面掌握了电动汽车充电桩/机校验仪的生产水平和质量状态,在大量实际数据的支撑下,对最小电流、温度系数、失真度、纹波等进行了溯源研究,掌握了关键参数值和检测方法,为相关国家规程的编写打下坚实基础。