母线差动保护在66kV变电所的应用

介绍母线差动保护装置的基本工作原理,结合本单位实际情况,对母线差动保护的二次电流回路及直流回路进行改进,使母线运行方式更加灵活,提高了系统保护的灵敏性和可靠性。     

MKT-I型扭矩仪的设计

简述了MKT－I型扭矩仪的系统设计及结构特点。     

Ordinal judgments of symbolic stimuli by capuchin monkeys (Cebus apella) and rhesus monkeys (Macaca mulatta): The effects of differential and nondifferential reward.

Ordinal learning was investigated in capuchin monkeys (Cebus apella) and rhesus monkeys (Macaca mulatta). In Experiment 1, both species were presented with pairings of the Arabic numerals 0 to 9. Some monkeys were given food rewards equal to the value of the numeral selected and some were rewarded with a single pellet only for choosing the higher numeral within the pair. Both species learned to select the larger numeral, but only rhesus monkeys that were differentially rewarded performed above chance levels when presented with novel probe pairings. In Experiment 2, the monkeys were first presented with arrays of 5 familiar numerals (from the range 0 to 9) and then arrays of 5 novel letters (from the range A to J) with the same reward outcomes in place as in Experiment 1. Both species performed better with the numerals, suggesting that an ordinal sequence of all stimuli had been learned during Experiment 1, rather than a matrix of two-choice discriminations. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

一种低复杂实现框架及在多码元差分检测中的应用

本文基于信息论考虑提出了一种低复杂实现的框架,对最大似然序列检测的分组（block)检测结构分析了该低复杂实现方案的性能并提出两命题,可用于寻求低复杂实现算法,另外,我们将该低复杂实现框架成功应用于高斯白声信道及衰落信道下多码元差分检测（MSDDD,multi-symbol differential detection)的低复杂实现,在基本保持其的条件下实现了检测复杂度多码元观察长度的线性增长,而最佳MSDD复杂度呈指数增工。     

BER Performance of Frequency Domain Differential Demodulation OFDM in Flat Fading Channel

A closed form expression for the bit error rate (BER) performance of frequency domaindifferential demodulation(FDDD) for orthogonal frequency division multiplexing system in flat fadingchannel is derived.The performance is evaluated by computer simulation and compared with the timedomain differential demodulation(TDDD).The results indicate that the performance of FDDD is betterthan that of TDDD,and the lower band of BER in the former is lower than that of the latter.     

SMT焊点元件与基板间隙的预测及其对焊点三维形态的影响

基于能量最小原理，采用三维有限元方法，考究了片式元件与基板的间隙对ＳＭＴ焊点三维开矿的影响，利用焊点系统的能量数据，分析元件与基板的间隙。研究表明，元件与基板的间隙对焊点三维形态有重要影响，元件与基板的间隙随焊点钎料量的增加和焊盘伸出长度匠减小而增加，提出了间隙与钎料量，焊盘伸出长度关系的回归模型。     

Effect of rapid solidification and small additions of Zn and Bi on the structure and properties of Sn-Cu eutectic alloy

The Sn-Cu eutectic alloy has been produced by rapid solidification using the melt-spinning technique, and both Zn and Bi have been added individually to it, in the ratio 0.5 wt.%. X-ray diffraction (XRD) analysis and differential thermal analysis (DTA) have been carried out. Resistivity, Vickers microhardness (HV), and yield stress (σ_y) have been measured. Also a new method for measuring creep has been described using a HV tester. The creep measured by this method is termed “microcreep.” It is a quick, nondestructive method and requires a small sample, about 1 cm², with thickness 1 mm or less. The results show that formation of Cu₃₉Sn₁₁ occurs due to the addition of both Zn and Bi. The addition of Zn increases HV and σ_y, but slightly lowers the creep resistance; however, the addition of Bi deteriorates the creep resistance. Also, it is found that the creep rate of as-quenched melt-spun alloys is high.     

新型移动互联网流量差异化集中计费架构及技术研究

引入新型移动互联网流量差异化集中计费方式,采用网络旁路方式,对用户上网内容采集、进行差异化标识,并集中在一点批价计费,实现基于特定应用、特定APN及特定时间段等流量差异化集中计费,为用户提供更透明、简单和易于理解的计费方式,给运营商带来更灵活的流量经营策略,为内容提供商创造有益的竞争环境。同时,通过集中计费处理方式,有效降低投资和维护成本。     

基于PCB差分功分网络的设计

射频印刷电路板(PCB)上互连线通常采用差分线的形式。当所传输的信号频率很高时,该结构需要利用混合模式的散射参数(S参数)进行研究。在一般射频网络单端S参数基础上,针对差分网络给出混合模式S参数的表达式。利用CST软件混合模式S参数设计了PCB上差分电路系统并进行了测试。实验结果表明,使用混合模式S参数能够快速准确设计出射频差分网络。     

机载高性能多格式视频叠加技术

随着计算机技术与视频图形图像技术的不断发展,机载航空电子系统中的综合显示处理技术也得以长足发展,需要处理和显示的视频信息量越来越大,格式越来越多。文章研究能够在机载综合显示系统中实现多种视频格式的选择和叠加功能。结合机载综合显示系统对视频技术的需求,研究了高性能多格式视频叠加模块的硬件设计和软件叠加算法。在机载综合显示系统液晶显示器上实现了叠加后的视频图像,满足了机载显示系统的要求。