美国UL484《房间空调器安全标准》的探讨

本文说明了在使用UL484《房间空调器安全标准》时应特别注意的诸如产品结构设计、材料使用和元件选择等问题,同时比照空调器国家安全标准进行讨论。文章列举UL标准中有特色的试验作为论据,如“温度压力试验”以及与IEC335-2-40的一些差异。     

大型发电机引出线手包绝缘处理方法

文中介绍了用电位外移测量法,检测发电机定子端部手包缘的密实性,及相对绝缘强度,以弥补端部绝缘缺陷的不足。     

无速度传感器感应电动机矢量控制系统速度辨识方法

分类介绍了当前研究的几种具有代表性的无速度传感器感应电动机矢量控制系统速度辨识方法,分析了各种方法的优缺点,并针对当前研究热点为今后的发展方向提出了一些设想。     

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.     

Enhanced dielectric properties of bismuth titanate/silver composites

Bismuth titanate (BiT) based composites containing silver particles are fabricated by a solution chemical process. Incorporation of silver particles does not result in unwanted reaction phase. SEM micrographs reveal fine silver particles distribute at BiT grain boundaries and into larger BiT plate-like grains. With the addition of silver, the dielectric constant increases up to ∼10 times higher than that of pure BiT ceramic, which can be attributed to the effective electric fields developed around the dispersed metal particles and the percolation effect. Additionally, the dielectric losses are significantly reduced by incorporating silver particles, and the values of BiT/Ag composites are lower than 0.5%. The dielectric properties of BiT/Ag composites are nearly frequency independent in the measured frequency range (1 kHz to 1 MHz).     

论袁枚性灵说情感理论的自然主义偏向

袁枚性灵说情感理论突破了儒家传统情感理论的藩篱,特别是脱离了宋明以来的理学思想的桎梏,而走向了注重个体自然情感的抒发,对传统文学功利主义是一次有力的反拨.这种理论偏向原因颇为复杂.     

高强度放电灯电子镇流器在城市照明中的应用

本文介绍了HID电子镇流器在城市照明中的节能应用。     

有机蒙脱石对酸性大红的吸附性能及吸附工艺条件优化研究

利用壳聚糖对纯蒙脱石进行有机改性,并对有机蒙脱石和纯蒙脱石吸附水溶液中酸性大红进行实验研究。结果表明吸附性能主要受吸附剂投加量,pH值和吸附时间等因素的影响;改性蒙脱石对酸性大红的吸附要优于纯蒙脱石。在本实验条件中,有机柱撑蒙脱石对水中酸性大红(50 ml,浓度为40 mg/l)的最佳吸附工艺条件为:pH2.5,投加量0.2 g,吸附时间35 min,此条件下对水中酸性大红去除率达到了71.26%。20℃时有机柱撑蒙脱石对酸性大红的等温吸附曲线符合Freundlich方程。     

Discrete-time analysis of a CPCH access scheme in W-CDMA

Common packet channel (CPCH) access is an efficient approach to support packet data transmissions in a wideband code division multiple access (W-CDMA) system. Rather than using a continuous-time analysis approach, this paper presents a discrete-time analysis of the CPCH access scheme to fully characterize the complete CPCH operation process. Previous studies using the continuous-time analysis only models a portion of the CPCH process. We assume that a packet arrival process is Poisson distributed and the service time of each packet is geometrically distributed. The study focuses on examining the number of packet arrivals in each CPCH access slot. Performance is evaluated in terms of normalized throughput and it is observed that CPCH performs better when packet mean service time is larger. The performance results are also compared with previous studies using continuous-time analyses