HBT Modeling

III-V heterojunction bipolar transistors (HBTs) enjoy several advantages over their conventional silicon cousins. These include: (1) a thinner base and lower base resistance which yields higher gain and f_max; (2) high breakdown voltage; (3) low parasitics; (4) high power density. The combination of a thin base (higher f_T), low base resistance (higher f_max), and low parasitics in particular make HBTs a suitable choice for high- frequency applications.     

电气化铁道异相供电方式向同相供电方式的转换

基于原牵引变电所的结构和接线,增设断路器和变流器.通过闭合和开断断路器,使牵引网电压相位一致,实现异相供电向同相供电的转换;变流器作为平衡变换装置,当端口接线角相差±90°时,采用背靠背单相变流器,相差±120°时,根据接线形式分别采用三桥三端子或三桥四端子变流器;根据所给出的补偿电流公式,不同的平衡变换装置均可输出期望的补偿电流,解决同相供电方式带来的负序电流叠加问题.仿真结果表明,平衡装置投入后,电力系统三相电流为对称的纯正弦基波波形与高频调制波形的叠加,是与电压同相位的正弦波.     

Emerging SiGe HBT reliability issues for mixed-signal circuit applications

We review the emerging reliability issues associated with high-performance SiGe HBT technologies which are being increasingly deployed in a wide variety of mixed-signal circuit applications. For the purposes of this work, we define the concept of device "reliability" to be broader than its standard usage in the industry, to include all possible transistor degradation mechanisms, for all possible mixed-signal circuit designs, in any of the various intended mixed-signal applications. For instance, in addition to classical device reliability mechanisms associated with reverse emitter-base and high forward current density stress, new reliability issues for SiGe HBTs, including impact-ionization induced "mixed-mode" stress, scaling-induced breakdown voltage compression and operating point instabilities, geometrical scaling-induced low-frequency noise variations, and the impact of ionizing radiation on device and circuit reliability, are also addressed.     

Tight electricity supply to return during winter

According to the National Development and Reform Commission (NDRC), China’s power supply will be tight this winter after a brief autumn respite because of a demand spike and uncertain     

能够提高用电安全性的“中性点开关”

文章介绍了中性点开关，并分析了在高压电网中应用中性点开关时将产生的积极效果。指出：在高压电网的中性点上安装中性点开关能够使高压开关获得零电压运行的安全条件；电网中的各种过电压如因为切换负载而产生的操作过电压在向中性点开关传输时将会受到中性点开关前面的电气设备阻抗的阻隔而显著减弱，因此可以提高中性点开关工作的安全性，避免停电损失。文章分析了在应用中性点开关时需要进行的设备改造，建议在各类电网中应推广使用中性点开关，以更加有利于电网的安全运行及提高供电质量。     

基于遗传算法的HBT干涉声定位阵列优化

针对声学定位性能易受麦克风阵列结构影响的问题,提出一种适用于汉伯瑞和布朗-特威斯（Hanbury and Brown-Twiss,HBT）干涉定位的遗传算法阵列结构优化方案。该方法以相邻两阵元距离差值为个体构造中间种群,按基因由升序排序转换到距离间隔种群。接着以方向图函数为适应度函数,构造基于最大旁瓣电平的目标函数,将麦克风间距作为优化对象,把目标函数转化为无约束优化问题。通过遗传算法求解该问题,得到定位性能最高的阵列结构。仿真结果表明七元阵优化效果最为显著,近点定位旁瓣峰值由0.4374降低至0,远点定位干扰旁瓣数降低至0。本文方法可以有效提高定位精度。     

A market approach to long-term security of supply

The problem of ensuring that there is enough generation capacity to meet future demand has been an issue in market design since the beginning of the deregulation process. Although ideally the market itself should be enough to provide adequate investment incentives, there are several factors that prevent this result from being achieved, and some actual markets have already experienced problems related with a lack of generation capacity. A regulatory framework to address this question is presented. The procedure is based on an organized market where reliability contracts (based on financial call options) are auctioned, so both their price and their allocation among the different plants are determined through competitive mechanisms. This results in a stabilization of the income of the generators and provides a clear incentive for new generation investment, with a minimum of regulatory intervention. Additionally, the method represents a market-compatible mechanism to hedge demand from the occurrence of high market prices     

利用神经网络预测供热负荷

阐述了神经网络的基本原理,编制了通用神经网络程序,并用此程序对某供热热源负荷进行了预测,预测结果与实际值相吻合,说明该神经网络是一种新颖、可靠的负荷预测方法.     

Ready to deliver? [security of supply]

This paper discusses how Britain's privatized energy market is working to ensure that there is enough gas and electricity to meet the demand. Since privatization, there has been around #30 billion invested in Britain's gas and electricity networks. This investment in unregulated infrastructure particularly demonstrates the response the market makes to deliver security of supply. Significant investment has also been made to build new plant when it is needed with the Renewables Obligation also leading to considerable investment in new renewable generation. There are also moves to address the upgrade and repair of networks that are more than 40 years old.     

供热系统的"垃圾改造"

为解决目前供热锅炉对环境造成的污染问题,改善空气质量,国家已经决定逐年快速取缔区域性锅炉和分散锅炉.我国面临着工业用热、民用采暖和生活用热量迅速增长的需求,为减少新建供热机组的投资,充分利用原有设备,节约能源,采用垃圾焚烧技术对现有锅炉进行改造,必将具有广阔的发展前景和市场需求.