坐标测量机激光非接触式测头的研制

本文介绍适用子精密大型测试仪器──坐标测量机的激光非接触式测头的研制。该测头采用ＰＳＤ作为敏感元件并采用单片机技术完成对测量数据的处理。     

复合材料四结点四边形多层退化壳单元

本文提出了一个复合材料四结点四边形多层退化壳单元。单元从修正的Hu-Washizu变分原理导出,独立假设位移场、每层内部应变场和应力场。文中给出了几个复合材料板和壳静力线性问题实例。计算结果表明本文的单元是准确和有效的。     

半绝缘InP（Fe）的低温氯化物VPE生长

介绍了一种半绝缘ＩｎＰ（Ｆｅ）的低温氯化物气相外延（ＶＰＥ）生长方法，生长温度为５５０℃，可为金属有机气相淀积的量子阱结构二次外延半绝缘ＩｎＰ（Ｆｅ）盖层。４０μｍ层厚时电阻率超过５×１０８Ωｃｍ，临界击穿电压达到１０Ｖ以上。用这种方法制备的激光器阈值电流达８０ｍＡ，较平板式的降低３倍，远场图样平行和垂直结平面方向光功率曲线对称性良好，远场发散角，器件测试得到较好光谱。目前尚未见到其它类似报道。     

基于IFMOP的玉环市区域水资源配置

引入无概率分布的区间数表示不确定性影响范围,选取经济效益、供需水效率和COD排放量分别构建经济目标、社会目标和环境目标优化函数,构建了玉环市不确定性模糊多目标规划(IFMOP)水资源配置模型,并计算了不确定性解集。结果表明:IFMOP配置计算成果可实现玉环市区域水量水质协调高效利用和社会-经济-生态系统均衡发展;在75%来水保证率下各行业配置总水量不确定性范围为14 375万~15 154万m³。IFMOP水资源配置模型在信息不充分的条件下能够全面使用各类数据信息进行水资源配置,更好地满足水资源在各行业配置过程中的动态管理需求。     

适用于复杂环境下的实时目标跟踪技术

针对复杂环境下目标跟踪过程中目标存在旋转、视角、尺度等变化以及噪声干扰的问题,提出了一种基于尺度不变特征与快速模板匹配相结合的目标跟踪技术;该技术通过分别提取预先存储模板和实时采集图像的尺度不变特征,建立初始模板;采用菱形搜索策略对模板的低分辨率子图和待跟踪图像的低分辨率子图进行快速互相关检测,根据检测结果在该帧高分辨率图像中建立紧凑ROI,在此区域内进行模板匹配,对目标进行精确定位;在目标跟踪的过程中采用自适应模板更新策略,以保证在目标发生变化时跟踪的稳定性;实验结果表明,该技术在稳定性、准确性和实时性等方面均优于传统方法。     

基于PLC的火电厂电除尘器振打控制的研究

为了提高火电厂中静电除尘器的稳定性、可靠性、自动化水平,采用了高性能施耐德Twido可编程控制器(PLC)以及Twidosoft编程软件,设计了电除尘器电机振打控制方案,编制了振打控制梯形图程序;当沉降室侧壁振打3分钟,停7分钟;第一电场振打2分钟,停8分钟;第二电场振打2分钟,停18分钟;第三电场振打2分钟,停28分钟时,振打效果较好;运行结果表明:采用Twido可编程控制器之后,实现了电机振打的自动运行,与传统继电器振打控制系统相比,可靠性高,稳定性好,除尘效率高,粉尘排放浓度低于50mg/m3,为火电厂静电除尘器电机振打系统的自动控制提供了新的方法。     

基于北斗卫星的森林火灾监控终端设计

针对传统森林火灾监控方式存在的受地形限制,导致火灾发现不及时和定位难的缺陷,设计了基于北斗卫星的森林火灾监控系统,实现了火灾智能识别和预警,并且可以对火源、火场进行快速定位和信息通报;终端包括烟采集处理模块、图像采集模块、DSP处理模块、ARM主控模块和北斗卫星通信模块五部分,从烟和火焰两个方面对森林实时进行监控,分别采用离子烟雾传感器和DSP火焰识别混合算法,提取火焰图像差值和火焰图像边界参数的方法,提高了识别的准确率;试验证明,系统具有结构简单、使用方便和识别智能化的特点。     

Optimal tracking performance of MIMO discrete‐time systems with communication constraints

The optimal tracking problem for multiple‐input multiple‐output linear‐time‐invariant discrete‐time systems with communication constraints in the feedback path is studied in this paper. The tracking performance is measured by the energy of the error signal between the output of the plant and the reference signal. The objective is to obtain an optimal tracking performance, attainable by all possible stabilizing compensators. It is shown that the optimal tracking performance consists of two parts, one depends on the nonminimum phase zeros and zero direction of the given plant, as well as the reference input signal direction, and the other depends on the nonminimum phase zeros, unstable poles, and pole direction of the given plant, as well as the bandwidth and additive white Gaussian noise of the communication channel. It is also shown that, if the constraint of the communication channel does not exist, the optimal tracking performance reduces to the existing tracking performance of the control system without communication constraints. A typical example is given to illustrate the theoretical results. Copyright © 2011 John Wiley & Sons, Ltd.     

Stability analysis and H∞ control for hybrid complex dynamical networks with coupling delays

This paper formulates and studies a model of complex dynamical networks with switching topology and coupling delays. Based on the hybrid control and Lyapunov function, the stability and robust H_∞ control of such networks with impulsive and switching effects, which have not been studied before, are addressed with some criteria derived. Examples are given to illustrate the effectiveness of the theoretical results. Copyright © 2011 John Wiley & Sons, Ltd.     

Optimal Performance in Tracking Stochastic Signal Under Disturbance Rejection

The analysis method of optimal tracking performance is proposed for multiple‐input multiple‐output (MIMO) linear time‐invariant (LTI) systems under disturbance rejection. An H₂ criterion of the error signal between the output of the plant and the reference signal is used as a measure for the tracking performance. Spectral factorization is applied to obtain the optimal solution of the system tracking error. The explicit expressions are derived for this minimal tracking error with respect to random reference signals under disturbance rejection. It is shown that the nonminimum phase zeros, the zero direction, the unstable poles, the pole direction of a given plant, statistical characteristics of the reference input signal, and disturbance signal have a negative effect on a feedback system's ability to reduce the system error with disturbance rejection. The results show that the optimal tracking performance will further be damaged because of disturbance rejection. Some typical examples are given to illustrate the theoretical results.