Adaptive control for a sensorless permanent-magnet synchronousmotor drive

An adaptive velocity controller for a permanent-magnet synchronous motor without using shaft sensor is presented. Two line-to-line voltages and two stator currents are sensed to produce the flux position. The design part is concerned with the formulation of control algorithm for current-regulated pulsewidth modulated inverter and vector control strategy for speed loop. Under the vector control framework, self-tuning, model following, and model referencing adaptive control are applied to design for the speed-loop controllers. The implementational part integrates the control of current and speed loop using microprocessor-based controllers. Experimental case studies that correlate simulation and measurement results are provided. The experimental results validate the theoretical development. A new approach for designing advanced adaptive controller for a sensorless ac drive is provided     

浅谈企业科研课题的组织与管理

论述企业科研课题及其成果的组织管理工作。     

Performance analysis for DOA estimation algorithms: unification,simplification, and observations

Subspace based direction-of-arrival (DOA) estimation has motivated many performance studies, but limitations such as the assumption of an infinite amount of data and analysis of individual algorithms generally exist in these performance studies. The authors have previously proposed a unified performance analysis based on a finite amount of data and achieved a tractable expression for the mean-squared DOA estimation error for the multiple signal classification (MUSIC). Min-Norm, estimation of signal parameters using rotational invariance techniques (ESPRIT), and state-space realization algorithms. However, this expression uses the singular values and vectors of a data matrix, which are obtained by the highly nonlinear transformation of the singular value decomposition (SVD). Thus the effects of the original data parameters such as numbers of sensors and snapshots, source coherence and separations were not explicitly analyzed. The authors unify and simplify this previous result and derive a unified expression based on the original data parameters. They analytically observe the effects of these parameters on the estimation error     

苏—27飞机燃油带式综合仪表的原理特点及维修途径

ＣＴＰ７－２ＡＫ燃油油量表－耗量表系统代表了俄罗斯当代燃油测控系统的水平。本文论述了ＣＴＰ７－２ＡＫ产品的组成、工作原理及技术特点，同国产及英美产品当前的技术水平做了比较，并在此基础上提出了今后维修和国产化的途径。     

基于TCP Vegas的LTE网络拥塞控制算法性能分析

TCP Vegas和TCP Reno相比,虽然性能更强,吞吐量更高,但若将TCP Vegas部署在新的网络上仍存在较多障碍。以4G的LTE系统中部署TCP Vegas为例,分别对慢启动阶段的阈值设置和拥塞避免阶段的拥塞避免机制作相应改进。使用NS-2网络仿真LTE模型,结果表明TCP Vegas与TCP Reno相比具有更好的性能。     

计算机多媒体辅助教学软件设计思想

本文根据几年来制作多媒体课件的实践，详细，系统地阐述了多媒体辅助教学软件开发的总体设计思想。     

Morphology and Frictional Characteristics Under Electrical Currents of Al203/Cu Composites Prepared by Internal Oxidation

Two AhO3/Cu composites containing 0.24 wt.% A1203 and 0.60 wt.% A1203 separately are prepared by internal oxidation.Effectsof sliding speed and pressure on the fi-ictional characteristics of the composites and copper against brass are investigated and compared.The changes in morphology of the sliding surface and subsurface are examined with scanning electron microscope (SEM) and energy dispersive X-ray spectrum (EDS).The results show that the wear resistance of the AI203/Cu composites is superior to that of copperunder the same conditions.Under a given electrical current,the wear rate of AI203/Cu composites decreases as the AleO3-content increases.However,the wear rates of the Al203/Cu composites and copper increase as the sliding speed and pressure increase under drysliding condition.The main wear mechanisms for AleO3/Cu composites are of abrasion and adhesion;for copper,it is adhesion,although wear by oxidation and electrical erosion can also be observed as the speed and pressure rise.     

高端品质 塑造未来——本刊总编辑刘柱与海克斯康测量技术(青岛)有限公司执行副总裁周亮博士对话

海克斯康测量技术(青岛)有限公司(以下简称海克斯康),作为中国目前技术最先进、实力最强的三坐标测量机制造厂商,已经成为制造企业值得信赖的合作伙伴,在制造过程中,海克斯康为用户提供了优质的解决方案,目前在国内市场的占有率达到了55%以上,而且这个数字还大有攀升之势.在多年的运营中,海克斯康是如何在激烈的市场竞争中立于不败之地的?海克斯康为航空航天领域提供了哪些优秀的解决方案?在全球金融危机的大形势下,海克斯康又是如何应对的?近日,本刊总编辑刘柱就一系列业内关注的问题对海克斯康执行副总裁周亮博士进行了专访.     

某型飞机后边条焊接盒段优化研究

某型飞机后边条焊接盒段是用于安装平尾的重要受力构件,由材料为30CrMnSiA的板弯件、机加件及加强筋焊接组合而成。由于盒段焊缝数量多、零件壁厚薄,故在组合焊接时容易出现焊接变形、变形后校形困难等问题,使焊缝质量难以保证。本文对焊接盒段结构方案进行了优化研究,在最终选定的结构优化方案中,其盒段壁板为整体机加成型,大量采用机械连接,焊缝数量少,焊接形式简单,缩短了盒段的焊接周期,改善了焊接盒段生产的工艺性,满足了该型号飞机的批产要求。     

捷联式移动平台重力仪地面测试结果

自主研制移动平台重力仪对我国矿产资源勘探及测绘等领域具有重要意义。研制了一种基于激光捷联惯导的移动平台重力仪,根据移动平台重力测量应用需求及激光捷联惯导系统特点,采用高精度石英挠性加速度计作为重力测量传感器,安装于系统垂向通道,既可作为导航用垂向加速度计,又用于实现标量重力测量。介绍了工程样机系统的组成。利用重力场随高度升高衰减的原理,以相邻楼层间的重力测量差值评价了系统的静态精度;通过地面跑车试验,获得了系统动态测量内符合精度。