变频器调速装置节能浅析

1概述 近十多年来,随着电力电子技术、微电子技术及现代控制理论的发展,变频调速技术已经广泛地用于交流电动机的速度控制,其最主要的特点是具有高效率的驱动性能及良好的控制特性.它是一种高新技术电力节能装置,它通过改变（降低）电源工作频率,来降低动力设备（电机）的转速,减少设备的输出功率,达到输出功率与工作负荷的最佳匹配,实现节能目的,有效地提高了经济效益和产品质量.几乎可以说,有电动机的地方就有变频器,在一切需要进行速度控制的场合,变频器以其操作方便、体积小、控制性能高而获得广泛应用.     

用LabVIEW演示PID控制规律

利用虚拟仪器技术,采用LabVIEW图形编程环境,设计了一个程序,用于演示PID控制规律,可将其用于教学中,以此为例说明LabVIEW对传统教学方法所带来的巨大变化.     

Synthesis of amphiphilic magnetic microspheres by dispersion copolymerization of styrene and poly(ethylene oxide) macromonomer

Amphiphilic magnetic microspheres ranging in diameter from 5 to 100 µm were prepared by dispersion copolymerization of styrene and poly(ethylene oxide) vinylbenzyl (PEO‐VB) macromonomer (MPEO) in the presence of Fe₃O₄ magnetic fluid. The effects of various polymerization parameters on the average particle size were systematically investigated. The average particle size was found to increase with increasing styrene concentration and initiator concentration. It also increased with decreasing stabilizer concentration and molecular weight of MPEO. The content of the hydroxyl groups localized in the microspheres ranged from 0.01 to 0.2 mmol g^?1. © 2003 Society of Chemical Industry     

产出水处理设备的腐蚀和机械磨损

提供了能够延长与产出水举升、加工、处置和注入有关的油气生产设备使用寿命的成功经验和技术,并按照产出水的处理程序进行介绍,即从油藏中的液体进入井筒到举升到地面(井筒管理),地面生产/加工设备和处理/注入设备的整个处理过程.由于井筒是最主要的设备,多数作业成本都与将液体举升到地面有直接关系,因此要重点强调井筒的管理.通过减少井的事故(抽油杆、油管和泵)可以大大降低操作成本,延长边缘井的生产时间.地面处理成本包括如何使泄漏、漏出物清洗及原油携带量降到最低的费用.上述经验来源于2002年8月对Permian盆地上成功优化水处理成本的作业商进行的采访;已发表的油气技术文献;本文作者在油气作业领域的个人经验(31年以上).     

WC/Cu复合材料制备及其高温性能

用机械合金化法结合冷变形，制备了WC／Cu复合材料，研究了冷变形后复合材料的组织特征和高温退火时韵性能变化。结果表明：烧结后的材料经冷变形，组织呈显著纤维状，WC颗粒弥散分布，密度明显提高，达到理论密度的99．2％；复合材料经600～900℃高温退火，强度和硬度略有下降，塑性则有大幅提高；900℃退火时未发生明显的再结晶，界面结合良好；所制备的WC／Cu复合材料有优良的综合性能。     

电磁超声流量计的研制

基于电磁声换能器的原理，研制了一种新型的电磁超声流量计，并讨论提高测量精度的措施。     

On the physical and logical topology design of large-scale optical networks

We consider the problem of designing a network of optical cross-connects (OXCs) to provide end-to-end lightpath services to large numbers of label switched routers (LSRs). We present a set of heuristic algorithms to address the combined problem of physical topology design (i.e., determine the number of OXCs required and the fiber links among them) and logical topology design (i.e., determine the routing and wavelength assignment for the lightpaths among the LSRs). Unlike previous studies which were limited to small topologies with a handful of nodes and a few tens of lightpaths, we have applied our algorithms to networks with hundreds or thousands of LSRs and with a number of lightpaths that is an order of magnitude larger than the number of LSRs. In order to characterize the performance of our algorithms, we have developed lower bounds which can be computed efficiently. We present numerical results for up to 1000 LSRs and for a wide range of system parameters such as the number of wavelengths per fiber, the number of transceivers per LSR, and the number of ports per OXC. The results indicate that it is possible to build large-scale optical networks with rich connectivity in a cost-effective manner, using relatively few but properly dimensioned OXCs.     

分布式光纤拉曼放大器的增益平坦设计

介绍了在波分复用（WDM）系统中分布式光纤拉曼放大器（FRA）的理论分析模型。在此基础上，对增益平坦设计所需考虑的因素进行了分析；最后通过试验证明了它的有效性。     

一种多晶硅高温压力传感器

制作压力传感器时，在二氧化硅层上淀积多晶硅膜，既可利用优良的机械特性，又可保证压敏电阻与衬底间具有良好的绝缘性，由此可大大提高器件的温度特性。介绍了一种多晶硅压力传感器的原理和设计。实验结果表明，这类传感器具有灵敏度好，精度高等特点，电路工作范围为０－２５０℃，且具有良好的温度稳定性。