点焊焊接电流波形的实时液晶显示系统

焊接电流对电阻点焊有着重要的影响,因此在点焊过程中实时显示焊接电流波形是十分必要的。文章设计了采用DSP器件TMS320LF2407A及TFTs6448b液晶控制器,实现对点焊电流波形的实时显示系统。系统设计实现了数据采集存储,并通过软、硬件结合的方式,满足了LCD的时序及实时显示要求。将研制的点焊电流液晶显示系统,在生产现场对NA-16点焊机的焊接电流波形进行了实时测试,在焊接过程中获得了失真度很小的点焊焊接电流波形。结果表明,文章提出的DSP点焊焊接电流波形的液晶显示系统设计是合理的,具有较高的显示精度及较好的实时性。     

视觉测量红外光点图像中心精确提取

提出了一种视觉测量中的红外光点图像中心提取方法。首先,使用一组阈值平面与红外光点灰度能量分布相交确定光点能量等高线,得到各等高轮廓点和阈值平面截得的能量包络。然后,利用最小二乘椭圆拟合等高线上轮廓点的椭圆中心,并计算阈值平面所截得的能量包络的质心,以椭圆中心和包络质心的黄金分割点作为等高层面上的光点中心。最后,利用各等高层面光点的中心获得红外光点图像中心的精确位置。试验验证结果表明,算法对红外光点图像中心提取可取得较高精度。目前,方法已在面阵静态红外地球敏感器标定中得到应用。     

双环斑激光束在克尔介质中的自聚焦和光斑分裂效应

实验上发现了双环斑激光束在克尔介质中的光斑分裂效应。理论上,通过数值求解非线性薛定谔方程,发现当输入光斑功率超过100 kW/cm2时,产生光斑分裂和自聚焦效应,该阈值明显小于单环斑激光的自聚焦和光斑分裂阈值。我们认为是双环之间的耦合效应导致了这种结果,并给出了具体分析。     

对不同洁净室测试规范中条文差异的探讨

本文根据有关国家标准和行业标准，结合工程测试实践，对洁净室洁净度测定中必要测点数及每个测点的必要采样次数等问题进行探讨。     

CAN网络分布式可视对讲系统研究

通过对CAN网络、可视对讲CAN智能节点的研究，开发CAN网络分布式可视对讲系统。这种多主的网络结构在可视对讲系统中得到了充分应用，阐述了设计中的几个主要技术和思想，包括CAN控制器网络、可视对讲CAN智能节点设计、CAN节点软件设计。此系统网络在小区、大楼、医院、仓库等的安防监控中具有广泛的应用价值。     

Fabrication of Spot Size Converters for Optical Chemical Sensors by Distributed-Field-Assisted Ion-Exchange

We propose a new method for fabricating optical waveguides with nonuniform thickness by controlling the electrical field distribution during the field-assisted ion-exchange. We refer to this method as distributed-fild-assisted ion-exchange. The distribution of the intensity of the electrical field was simulated for different electrode configurations, and was compared with experimental diffusion depth distribution of K⁺—Na⁺ exchange in sodalime slide glass. A unique bath was designed for the distributed-field-assisted ion-exchange. Using a three-electrode configuration, we obtained, for instance, a 2 cm-long spot size converter with thickness changes of from 12 μm to 2 μm. This technique can be used to fabricate waveguides for optical chemical sensors.On leave from State Key Laboratory of Transducer Technology, Institute of Electronics, Chinese Academy of Sciences, Beijing, China 100080.     

真空短间隙微弧级联效应观测

利用0.5 mm间隙微通道板成像器观测了微弧放电的斑点级联效应.实验发现,微弧阴极斑点的运动轨迹呈多类型的折线轨迹,斑点间隙在200—300 μm,首发射阴极斑点的放电强度比次级斑点高一个量级以上,而且次级斑点之间的放电强度相对稳定,次级斑点在放电阴极表面无融蚀现象.实验表明,次级斑点产生机制与首发射存在较强的依赖关系. 关键词： 阴极斑点 微弧级联 微通道板成像器     

An unequal cluster-based routing protocol in wireless sensor networks

Clustering provides an effective method for prolonging the lifetime of a wireless sensor network. Current clustering algorithms usually utilize two techniques; selecting cluster heads with more residual energy, and rotating cluster heads periodically to distribute the energy consumption among nodes in each cluster and extend the network lifetime. However, they rarely consider the hot spot problem in multihop sensor networks. When cluster heads cooperate with each other to forward their data to the base station, the cluster heads closer to the base station are burdened with heavier relay traffic and tend to die much faster, leaving areas of the network uncovered and causing network partitions. To mitigate the hot spot problem, we propose an Unequal Cluster-based Routing (UCR) protocol. It groups the nodes into clusters of unequal sizes. Cluster heads closer to the base station have smaller cluster sizes than those farther from the base station, thus they can preserve some energy for the inter-cluster data forwarding. A greedy geographic and energy-aware routing protocol is designed for the inter-cluster communication, which considers the tradeoff between the energy cost of relay paths and the residual energy of relay nodes. Simulation results show that UCR mitigates the hot spot problem and achieves an obvious improvement on the network lifetime. Guihai Chen obtained his B.S. degree from Nanjing University, M. Engineering from Southeast University, and PhD from University of Hong Kong. He visited Kyushu Institute of Technology, Japan in 1998 as a research fellow, and University of Queensland, Australia in 2000 as a visiting professor. During September 2001 to August 2003, he was a visiting professor at Wayne State University. He is now a full professor and deputy chair of Department of Computer Science, Nanjing University. Prof. Chen has published more than 100 papers in peer-reviewed journals and refereed conference proceedings in the areas of wireless sensor networks, high-performance computer architecture, peer-to-peer computing and performance evaluation. He has also served on technical program committees of numerous international conferences. He is a member of the IEEE Computer Society. Chengfa Li was born 1981 and obtained his Bachelor’s Degree in mathematics in 2003 and his Masters Degree in computer science in 2006, both from Nanjing University, China. He is now a system programmer at Lucent Technologies Nanjing Telecommunication Corporation. His research interests include wireless ad hoc and sensor networks. Mao Ye was born in 1981 and obtained his Bachelor’s Degree in computer science from Nanjing University, China, in 2004. He served as a research assistant At City University of Hong Kong from September 2005 to August 2006. He is now a PhD candidate with research interests in wireless networks, mobile computing, and distributed systems. Jie Wu is a professor in the Department of Computer Science and Engineering at Florida Atlantic University. He has published more than 300 papers in various journal and conference proceedings. His research interests are in the areas of mobile computing, routing protocols, fault-tolerant computing, and interconnection networks. Dr. Wu serves as an associate editor for the IEEE Transactions on Parallel and Distributed Systems and several other international journals. He served as an IEEE Computer Society Distinguished Visitor and is currently the chair of the IEEE Technical Committee on Distributed Processing (TCDP). He is a member of the ACM, a senior member of the IEEE, and a member of the IEEE Computer Society.     

大气湍流对舰载激光通信中光能量分布的影响

针对激光在洋面上大气湍流中传输时,光能量分布发生变化,影响激光通信质量。本文基于大气光通信信道模型,对激光在大气湍流中的传输进行模拟,分析大气折射率结构常数、传输激光的波长,传输距离对光能量分布的影响,并用MATLAB对其影响进行了数值模拟。结果表明：在仅考虑大气湍流对激光传输影响的条件下,传输激光的波长对光能量分布具有重要影响。     

用于CATV的DFB激光器同轴封装激光焊接技术研究

激光焊接技术广泛应用于光电子封装领域,它能形成很强的结合力,显示出无可比拟的优越性.但激光脉冲形状设置仍存在一定缺陷.研究了用于CATV的DFB激光器同轴封装激光焊接技术,利用Nd:YAG激光焊接系统,在两种不同的激光脉冲形式下,对DFB激光器和光纤进行焊接,分析了焊点宽度、深度与激光脉冲的关系.通过推力实验,测得DFB激光器输出先功率的变化大小,验证焊点质量,得出实际生产中脉宽为5 ms和2 ms、电压为310 V和360 V的激光脉冲,从而提高了焊接质量和工艺水平.