Preparation and densification of superconducting YBa2Cu3Ox ceramics

The solid-state reaction method to form the superconducting oxide YBa₂Cu₃O _x was studied. It was found that the starting cupric and yttrium components accelerated the decomposition of the BaCO₃ component. At a constant heating rate of 10 ° Cmin^–1 in thermogravimetric analysis, the temperature of complete decomposition,T _f, was lowered from greater than 1000 ° C in pure BaCO₃ to between 915 and 985 ° C. The effectiveness in decreasingT _f can be ranked in the order of oxalate, carbonate and oxide. The highest sintered density achieved in this study was 6.03 g cm^–3 (/_th = 95%) at 990 ° C and 5.85 g cm^–3 (/_th = 92%) at 960 ° C. The source of cupric ion had the largest effect on densification. The use of cupric carbonate resulted in a consistently high Archimedes density of about 6.00gcm^–3 and large dimensional shrinkage of about 20% at 990 ° C for 12h. In contrast, the use of cupric oxide gave the lowest density and smallest shrinkage. Within the same powder lot, higher sintered density and smaller dimensional shrinkage were observed in samples with higher initial green density and compaction pressure. However, the data suggested that the enhanced densification and higher density achieved by the use of cupric carbonate and oxalate cannot be accounted for by the different physical characteristics of the powders and the mechanics of powder compaction, measured collectively by the green density.     

KYN44-12型中置柜联锁装置的改进设计

介绍了12kV中置柜联锁装置的设计原则,分析了现有中置柜联锁装置在实际运行中存在的问题和不足,提出了改进和完善中置柜联锁装置的设计方法。实际应用表明,改进后的中置柜联锁装置的功能更加完善,安全性更加可靠,完全达到了五防闭锁要求。     

中置式高压电容器柜改进设计

分析了南屯煤矿白马河风井变电所高压电容器柜原设计方案存在的问题,并对其进行了改进设计:选用适用于容性负载的真空断路器;添加放电线圈,并将放电线圈与电容器直接并联,使放电线圈与电容器组成一个完整的放电回路;添加接地开关,接地开关既有机械闭锁又有电气联锁,操作方便,安全性高。实际应用表明,改进设计后的高压电容器柜功能更加完善,更加安全、可靠。     

面向IC装备功能仿真平台的多模式测试方法

为了实现全面对IC装备以及装备功能仿真平台进行功能测试,通过分析装备命令响应特点,提出了包含单指令测试、逻辑指令序列测试以及随机指令序列测试的多模式测试方法;单指令测试验证设备以及由相关设备组成的系统的单指令响应正确性;逻辑指令序列从控制系统角度验证设备或系统的连续动态运行性能;随机指令序列测试验证设备或系统的动态随机响应性能;实际应用表明,提出的测试方法可以满足IC装备功能仿真平台的测试需求。     

网络环境下小学信息教学策略的探究

随着网络技术的不断发展和完善,使得传统意义上的教育有了突破时空限制的张力,引发了教育体制、教育观念、教育思想、教学模式、教学方法和教学内容的深刻变革。面对这种新的机遇与挑战,如何使每位学生都得到充分的发展,关键是教师应适应时代的要求,利用好网络教学资源环境,根据学生身心发展和学习的特点,构建科学合理的网络教学模式,从而培养学生"自主、合作、探究"的学习能力,实现对所学知识的再发现、再创造,实现思维的自主放飞,以适应信息化教育发展趋势。     

CPF低功耗设计的等价性验证策略

文章介绍低功耗设计的方法,着重介绍CPF相关低功耗设计特点。最后总结针对CPF低功耗设计的等价性验证方法,重点讨论隔离单元的验证。     

A cognitive-experiential approach to modelling web navigation

Flow experience, the degree to which a person feels involved in a particular activity, is an important influence on human–computer interaction. Building on Guo and Poole’s (2009) model of flow experience in Web navigation, and van Schaik and Ling's (in press) cognitive-experiential approach to modelling interaction experience, this research demonstrates the crucial role of the preconditions of flow experience in human–computer interaction. In an experiment, the preconditions of flow experience – but not flow experience proper – mediated the effects of artefact complexity, task complexity and intrinsic motivation (as a situation-specific trait) on both flow and task outcome. However, preconditions did not predict overall artefact evaluation. Within a staged model of flow experience, the broader implications of this work for human–computer interaction are explored.     

Dynamics and genetic fuzzy neural network vibration control design of a smart flexible four-bar linkage mechanism

In this paper, a dynamic modeling method and an active vibration control scheme for a smart flexible four-bar linkage mechanism featuring piezoelectric actuators and strain gauge sensors are presented. The dynamics of this smart mechanism is described by the Discrete Time Transfer Matrix Method of Multibody System (MS-DTTMM). Then a nonlinear fuzzy neural network control is employed to suppress the vibration of this smart mechanism. For improving the dynamic performance of the fuzzy neural network, a genetic algorithm based on the MS-DTTMM is designed offline to tune the initial parameters of the fuzzy neural network. The MS-DTTMM avoids the global dynamics equations of the system, which results in the matrices involved are always very small, so the computational efficiency of the dynamic analysis and control system optimization can be greatly improved. Formulations of the method as well as a numerical simulation are given to demonstrate the proposed dynamic method and control scheme.     

机动车车牌识别中SVM的应用

支持向量机是一类新型机器学习方法,成功应用于各个领域,算法在分类性能上优于其它学习算法。该文在字符特征提取基础上,将支持向量机理论应用于车牌识别系统,提高识别率和识别速度,具有很好的推广价值。