减小压电陶瓷驱动电源纹波的一种有效方法

为了解决直流放大式压电陶瓷驱动电源在实际应用中存在输出电压纹波较大且幅值随输出电压大小而改变的问题，对其工作原理进行了深入分析，在此基础上提出了采用恒流源代替基在级电路负载的方法。实验表明，这种有效地抑制了电源的纹波及其变化。     

磁悬浮硬盘中非记录磁场的研究

介绍了磁悬浮硬盘的概念，测量并分析了普通硬盘的音圈电机和主轴电机产生的非记录磁场以及磁悬浮硬盘中的磁力轴承产生的非记录磁场，分析了非记录磁场对记录磁场的影响，为磁悬浮硬盘的设计和研究提供了依据。     

Analysis of the effects of end connection quality on the dielectric loss of metallized film capacitors

Plasma sprayed metal end connections of metallized film capacitors are the weak link for pulse power applications which involve discharge times of tens of microseconds and less. This problem will only get worse with increased capacitor energy density. The present contribution quantifies the relationship between the "quality" of the end connection and dielectric loss of the capacitor winding. The analysis suggests that even for very poor end connections, the effect on dielectric loss of the total capacitor is relatively small. This makes a low stress production test for end connection quality problematic since such tests can only show the total capacitor dissipation factor resulting from various factors.     

Preparation and Photolunlinescence of Ordered ZnO Nanowire Arrays

Ordered ZnO nanowire arrays embedded in anodic aluminum oxide (AAO) membranes were fabricated by electrochemical deposition of Zn(NO3)2+H3BO3 solution in a boiling bath. Scanning electron microscope (SEM) and transmission electron microscope (TEM) observation results show that the polycrystalline ZnO nanowires with diameters around 100 nm were uniformly assembled into the ordered nanochannels of the AAO. The results of the investigation into photoluminescence (PL) and electronic paramagnetic resonance (EPR) measurements reveal that the interfaces between the ZnO nanowires and the pore walls of the AAO create a lot of oxygen vacancies, which are responsible for the green light emission (peaking around 512 nm) and the huge enhancement of the PL emission.     

基于Agent的股票交易模拟及应用

股票市场是市场经济的重要组成部分。但是现有的基于演绎推理的理论分析方法在处理股市这类复杂性系统时遇到了很多困难,因此基于归纳推理的实验经济学方法成为一种可行的选择。论文基于多Agent系统,采用再励学习算法模拟交易者行为特征,实现了一个股票市场的模拟系统,并且应用这一系统研究了涨跌停板交易机制对于股市的影响。     

基于迭代回溯的数据库查询优化算法

查询优化器是数据库系统最重要的组件之一。该文提出了一类新的查询优化算法,并对其性能进行了评估、讨论。它是基于分层回溯的一种查询优化算法,其优点主要在于对于一些复杂的应用环境,它在枚举算法的高复杂性和算法产生方案的质量之间取一个权衡点,以产生“次优”的优化结果来换取算法的执行效率,大大节省了运行环境的资源。该算法可以应用于当今一些新型数据库,如对象数据库和XML数据库等。     

直动式溢流阀的分岔分析与实验

为了改善广泛应用的直动式溢流阀的颤振行为,考虑油液压缩性、管道弹性和阀芯碰撞阀座时的能量损失,建立了溢流阀无量纲形式的数学模型。以4种不同的弹簧预压缩量,作出了相位和向量场分布图,得到了系统的稳定平衡状态。应用非光滑动态系统理论和计算软件MATLAB,画出了单参数和双参数分岔图,发现系统存在Hopf分岔、极限环鞍结点分岔、广义Hopf分岔和尖点分岔等分岔现象。搭建了测试平台,得到了阀芯位移分岔图和频谱瀑布图,对数学模型进行了实验验证。结果表明,小流量时为混沌或周期碰撞震荡,增大流量可改善阀芯颤振行为,为周期非碰撞震荡或稳定平衡状态。此研究工作为直动式溢流阀的失稳机理和颤振行为提供了理论依据。     

核级阀门流体阻断试验技术研究

在试验装置上开展了压水堆运行参数范围内动力驱动阀门的流体阻断试验研究和止回阀的动态逆流与静态逆流试验研究。试验结果表明：开展动力驱动阀门流体阻断试验时，在设施能力不足的情况下可将阀门开启度适当减小，也能验证阀门阻断流体的能力；止回阀静态逆流试验相较于动态逆流试验能更苛刻地考验止回阀的阻断性能。本文结果可为开展同类验证试验在试验方法的选取上提供依据。     

3D QSAR Studies,Pharmacophore Modeling and Virtual Screening on a Series of Steroidal Aromatase Inhibitors

Aromatase inhibitors are the most important targets in treatment of estrogen-dependent cancers. In order to search for potent steroidal aromatase inhibitors (SAIs) with lower side effects and overcome cellular resistance, comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA) were performed on a series of SAIs to build 3D QSAR models. The reliable and predictive CoMFA and CoMSIA models were obtained with statistical results (CoMFA: q² = 0.636, r²_ncv = 0.988, r²_pred = 0.658; CoMSIA: q² = 0.843, r²_ncv = 0.989, r²_pred = 0.601). This 3D QSAR approach provides significant insights that can be used to develop novel and potent SAIs. In addition, Genetic algorithm with linear assignment of hypermolecular alignment of database (GALAHAD) was used to derive 3D pharmacophore models. The selected pharmacophore model contains two acceptor atoms and four hydrophobic centers, which was used as a 3D query for virtual screening against NCI2000 database. Six hit compounds were obtained and their biological activities were further predicted by the CoMFA and CoMSIA models, which are expected to design potent and novel SAIs.     

Research on Failure Occurred During Switching in Bypass Pair of Valve Base Electronics for Converter Station

In the paper"Research on Failure Occurred During Switching in Bypass Pair of Valve Base Electronics for Yulong Converter Station,"the author proposed a control strategy basedon shortest job first algorithm.Shortest job first