应用等效电路模型的频率选择表面有效分析

给出了一种基于等效电路模型的频率选择表面(FSS)快速分析方法。对任意形状单元的FSS结构,采用并联组合形式的LC等效电路,并通过全波模式展开分析,采用线性最小平方拟合和线性代数方法求得到其等效电路参数。对三极形单元夹嵌FSS结构实例的分析表明,文中方法与全波分析结果的一致性非常好,并便于FSS结构的最优化设计,可扩展到多层FSS结构的分析。     

A systematic study on the growth of PZNT films by LPE method

Liquid phase epitaxy (LPE) was used to grow (1−x)Pb(Zn_1/3Nb_2/3)O₃−xPbTiO₃ (PZNT) films on different substrates. The morphology and epitaxial relationship of PZNT films with these substrates were investigated by optical microscopy and XRD. It was found that PZNT grains on planes of (001) MgO, (001) LaAlO₃ (LAO) and two specific planes of SrTiO₃ (STO), i.e. (110) or (111), distribute randomly and show no evident epitaxial relationship with these substrates. However PZNT films on (001) STO substrates exhibit very encouraging in-plane epitaxial relation: [100](001)_PZNT // [100](001)_STO, which was observed directly by OM, SEM and further confirmed by X-ray diffraction.     

The structural and electrical properties of nano-scale Sr2FeMoO6 under high pressures

Using the polymer-network gel method to control the chemical procedure, Sr₂FeMoO₆ powders with grain size of 50 nm (A) and 100 nm (B) have been synthesized, and their structural and electrical properties have been investigated. By comparing the experimental results of samples A and B with that of bulk sample C with grain size in μm obtained before, sample A shows the largest bulk modulus B ₀ and a relatively large slope of the drop in resistance as a function of pressure. The possible reasons are given and discussed.     

Preparation of silver nanoparticles via a non-template method

Silver nanoparticles have been prepared by a non-template method. Silver nitrate can be easily decomposed into silver nanosized materials. Small nanoparticles (less than 2 nm) can be formed in aqueous solution. Larger silver particles of about 100 nm can be formed in ethanol solution. By rationally adjusting the experimental conditions we finally obtain silver particles of about 20 nm with a relatively narrow distribution in ethanol solution. Differing from the previous reports, we find that silver nanoparticles can be formed by direct decomposition of AgNO₃ under UV light irradiation. No catalyst like TiO₂ is needed at all. We believe that it is a further step to precede the preparation of silver nanometer sized materials.     

蚁群算法在配电网冷负荷恢复中的应用

配电网长时间停电后,负荷会失去多样性,引起冷负荷故障恢复问题.为防止变压器过热,通过隔离开关实现配电网负荷的逐步恢复.在电力市场新规则下,电力公司将会因为供电质量不符合要求,而受到严重的惩罚.该文的目标函数考虑了电力市场的影响,采用蚁群算法,选取最优的负荷恢复次序,实现对顾客的公平和供电公司的经济利益.实例计算表明该方法可行、有效.     

基于Matlab的交直流混合输电系统的仿真研究

利用SimPowerSystems工具箱建立了一个两交一直的交直流混合输电系统模型,并对交流故障、直流故障下的系统稳定性和动态响应进行了分析,并给出了仿真结果.通过与交流输电系统仿真结果进行了比较,可以看出,由于直流输电系统的调节速度快和短时过载能力强的特点,所以交直流输电系统具有更好的稳定性能和响应速度.     

广州城区电网黑启动方案的分析计算

广州电网存在多种小概率事件引起电网大面积停电的运行风险,制定广州地区电网特别是城区电网黑启动方案需考虑的特殊问题有:城区电网黑启动电源少;电缆线路多,可能引起过电压;与省级电网黑启动方案的协调配合;地区110kV电网解环运行、3T接线多;调度权限.重点分析和探讨了广州城区电网的多个黑启动路径,并对其黑启动方案开展了发电机自励磁、工频过电压、合空线过电压、合空变过电压、潮流等方面的详细仿真计算,综合多种因素给出了广州城区电网黑启动方案的优先级及其前提条件.     

粉末活性炭和超滤膜组合工艺深度处理黄浦江原水

目的为了提高黄浦江原水中溶解性有机物的去除效果。进一步提高上海自来水水质．方法采用粉末活性炭（PAC）和超滤膜（UF）组合工艺深度处理黄浦江原水．结果粉末活性炭投加量增加可以提高工艺对水体中有机物的去除效果．在投加量为22．0mg／L的条件下，对CODMn、UV254和TOC的去除率分别为33．5％、40．67％、25％，出水CODMn可以达到国家水质标准的要求．该工艺能够有效地保证出水浊度，也能够有效地降低出水的致突变活性．结论PAC和UF组合工艺能有效地降低水体中溶解性有机物的浓度，减少消毒过程中三卤甲烷和四氯化碳的生成量．采用PAC和UF组合工艺深度处理黄浦江原水是可行的．     

新时期我国高技能人才短缺的原因分析及对策研究

近年来，我国众多行业中出现了高技能人才普遍短缺的现象，成为制约企业发展的一个瓶颈。通过高技能人才现状及短缺的原因分析，认为要加强高技能人才队伍建设，必须树立正确的人才观念，优化高技能人才的成长环境，打破干部、工人的身份界限建立科学合理的高技能人才薪酬制度。     

基于Matlab的交直流混合输电系统的仿真研究

利用S imPowerSystem s工具箱建立了一个两交一直的交直流混合输电系统模型,并对交流故障、直流故障下的系统稳定性和动态响应进行了分析,并给出了仿真结果。通过与交流输电系统仿真结果进行了比较,可以看出,由于直流输电系统的调节速度快和短时过载能力强的特点,所以交直流输电系统具有更好的稳定性能和响应速度。