分布式光纤测温系统在小湾拱坝温度监测中的运用

小湾水电工程拱坝内铺设了10 km的分布式测温光纤,为目前国内之最.本文总结了测温光纤在常态混凝土下施工埋设,特别是在当前国内没有相关技术规范的情况下,对测温光纤的率定和施工中存在的问题进行了总结.小湾大坝绘制出温度场分布图,为大坝温控工作提供了较为精准的数据依据,为今后测温光纤的推广和使用提供宝贵的经验.     

基于GPRS的闸门监控系统设计

利用通用分组无线电业务(GPRS)通信技术、可编程逻辑控制器(PLC)和RS-485总线设计了稳定、经济的分布式闸门监控系统。该系统采用Internet/数字数据网(DDN)和GPRS Modem方式接入无线通信网络,并根据闸门监控系统的运行特点,采用GPRS实时通信与短信服务(SMS)通信相结合的方式,不仅保证了系统通信的稳定性和平衡性,且优化了系统的运行成本。最后,对基于GPRS的闸门监控系统的经济性和适用性进行了讨论。     

Compact Dipole Antenna for Terrestrial Digital Multimedia Broadcasting Service

A compact dipole antenna for the terrestrial digital multimedia broadcasting (TDMB) application is presented. The length of the antenna is about 0.06λ at the TDMB resonance frequency of 190 MHz. Miniaturization of the antenna is achieved by using meander structures and lumped elements. The proposed antenna has two resonance frequencies and covers the TDMB band from 174 MHz to 216 MHz in Korea. The antenna has good impedance bandwidth and radiation characteristics for the TDMB. The experimental results of the designed dipole antenna are presented and analyzed.     

Tree-Based Concurrency Control in Distributed Groupware

We present a novel algorithm, called dARB, forsolving the concurrency control problem indistributed collaborative applications. Themain issue of concurrency control is resolvingthe conflicts resulting from simultaneousactions of multiple users. The algorithmreduces the need for manual conflict resolutionby using a distributed arbitration scheme. Themain advantages of our approach are thesimplicity of use and good responsiveness, asthere are no lock mechanisms. Our algorithmrequires the applications to use a tree as theinternal data structure. This makes itapplication independent and suitable forgeneral collaborative applications. The treerequirement is reasonable since many newapplications use XML (extensible MarkupLanguage) for data representation and exchange,and parsing XML documents results in treestructures. Example applications of thealgorithm, a group text editor and acollaborative 3D virtual environment calledcWorld, are implemented and evaluated in theDISCIPLE collaboration framework. We alsointroduce awareness widgets that users avoidgenerating the conflicting events and help inmanual conflict resolution.     

Centum-CS系统组态调试及维护

简要介绍了在洛阳石油化工总厂广泛使用的日本横河公司Centum—CS控制系统的组成，着重讨论了系统组态调试经验，以及日常维护和故障的分析判断处理。     

MHD simulation of high-current subsonic vacuum arc under different distributed axial magnetic fields

Based on two-temperature magnetic hydrodynamic (MHD) model, the influence of saddle-shaped distributed axial magnetic field (AMF, linearly increases along radial position) and bell-shaped distributed AMF (linearly decreases along radial position) on plasma loss and heat flux density to anode in subsonic high-current vacuum arc (HCVA) is simulated and analyzed. According to the simulation results, the saddle-shaped AMF can more effectively inhibit plasma loss from arc column than that of bell-shaped AMF. Comparisons between simulation results and experimental results further verify the correctness of model and simulation.     

Proactive resource allocation for asynchronous real-time distributed systems in the presence of processor failures

We present two proactive resource allocation algorithms, RBA^*-FT and OBA-FT, for fault-tolerant asynchronous real-time distributed systems. The algorithms consider an application model where task timeliness is specified by Jensen's benefit functions and the anticipated application workload during future time intervals is described by adaptation functions. In addition, we assume that reliability functions of processors are available a priori. Given these models, our objective is to maximize aggregate task benefit and minimize aggregate missed deadline ratio in the presence of processor failures. Since determining the optimal solution is computationally intractable, the algorithms heuristically compute sub-optimal resource allocations, but in polynomial time. Experimental results reveal that RBA^*-FT and OBA-FT outperform their non-fault-tolerant counterparts in the presence of processor failures. Furthermore, RBA^*-FT performs better than OBA-FT, although OBA-FT incurs better worst-case and amortized computational costs. Finally, we observe that both algorithms robustly withstand errors in the estimation of anticipated failures.     

A Low-Complexity Multiuser Detector for Asynchronous CDMA QPSK Adaptive Antenna Array Systems

This paper proposes a low complexity joint space-time multiuser detection algorithm for asynchronous DS/CDMA antenna array systems. The proposed multiuser detector is composed of an adaptive antenna array, used as a linear beamformer, and a sliding window decorrelator. A QPSK modulation scheme is used in order to increase bandwidth efficiency. Numerical results are given in terms of Bit Error Rate (BER) under the assumption of a frequency-selective Rayleigh slow fading channel. In particular, the proposed receiver is shown to be near-far resistant, even in worst fading cases, and to exploit completely array introduction while maintaining acceptable computational complexity. The proposed architecture avoids linear filter realization of the decorrelator, which is impractical in the case of a large number of users, and operates with relatively short data frames instead of the complete information sequence. Finally, this receiver is very flexible to changes in timing configuration.     

基于RS485总线的面粉厂集散控制系统

概述了面粉厂的基本状况及技术要求，详细介绍了面粉厂控制系统的控制方案及设计方法。给出了基于RS485总线集散控制系统的硬件配置和软件设计。系统实际应用表明，该方法为实现低成本的网络控制系统提供了一个实例。     

MAX6625型温度传感器的原理及应用

MAX6625是美国Maxim公司生产的一种新型智能温度传感器,它在风扇控制、温度告警、系统温度测量及工业设备中得到了广泛应用.介绍MAX6625的功能和结构,分析MAX6625的工作原理,给出采用MAX6625进行温度测控的电路及编程.