一种高功率因数的串联变频方案

本文介绍了一种高功率因数的串联变频方案,其新颖之处在于主电路采用晶体管和晶闸管混合逆变器,控制电路全由集成电路组成,文中详细介绍了该串联变频方案的组成和工作原理,并给出了满意的实验结果。     

用六节点三角元计算三相变压器的漏抗

本文用六节点三角元计算了三相变压器的漏抗,同时用三节点、六节点三角元计算了矩形槽中载流导体的矢量位和磁感应强度,并将两种方法的计算结果与解析值进行了对比。从计算结果看,在计算时间相近的情况下,六节点三角元计算磁场的精度远远高于三节点三角元。     

多硫化钠/溴氧化还原液流电池

介绍了氧化还原储能电池的原理与特点，它具有成本低、寿命长、效率高、响应快等优点。大连化学物理研究所在多硫化钠／溴氧化还原液流储能电池的研究上取得突破性进展，组装的单电池50次循环能量效率保持在80％以上，循环性能稳定，在此基础上成功研制了百瓦级、千瓦级电堆系统。开发这一与可再生能源配套的储能技术在当前显得特别重要与迫切，对推动我国国民经济可持续发展具有重大战略意义。     

全球风电成本的初步分析

通常，风电被认为在经济性上没有什么竞争力。但，据Poul Erik Morthorst和Hugo Chandler两位的统计，在过去的15年里，风电的实际成本已经下降了50％之多，而且这种趋势还在继续。     

基于PID控制的摩托车耐久试验台的研制

本文以工控机为控制核心,设计了一种新型摩托车耐久试验台,用计算机控制代替人工操作,提高了摩托车耐久试验的自动化程度。文中叙述了该试验台的系统结构及软、硬件的组成,并详细阐述了用改进的PID算法控制摩托车车速的过程。实践证明:该试验台精度较高、性能稳定,适合实际应用。     

工业炉内火焰图像在线检测系统及其试验

要实现工业炉内三维温度场的可视化,必须采集炉内的辐射图像。用两只火焰图像探测器和相应的计算机图像采集处理系统,在武钢热轧带钢厂3#加热炉中进行了火焰图像在线检测的试验研究。首先介绍了系统的硬件特别是探头的冷却系统配置情况;随后进行烧嘴调试试验,检验了系统的运行情况,特别是检验了探头摄取的图像质量,良好的图像质量为下一步图像处理和三维温度场可视化提供了有效的保证。     

Development of a Highly Selective,Sensitive, and Fast Response Upconversion Luminescent Platform for Hydrogen Sulfide Detection

Hydrogen sulfide (H₂S) has been recognized as one of most important gaseous signaling molecules mediated by a variety of physiological and pathological processes. Yet, its functions remain largely elusive due to the lack of potent monitoring methods. Hereby this issue is addressed with a powerful new platform—dye‐assembled upconversion nanoparticles (UCNPs). A series of chromophores with different absorption bands and fast responses towards H₂S is combined with UCNPs and results in a library of H₂S sensors with responsive emission signals ranging from the visible to the near‐infrared (NIR) region. These nanoprobes demonstrate highly selective and rapid responses to H₂S in vitro and in cells. Furthermore, H₂S levels in blood can be detected using the developed nanoprobes. Hence the reported H₂S sensing platform can serve as a powerful diagnostic tool to research H₂S functions and to investigate H₂S‐related diseases.     

Low-rate turbo-Hadamard codes

This paper is concerned with a class of low-rate codes constructed from Hadamard code arrays. A recursive encoding principle is employed to introduce an interleaving gain. Very simple trellis codes with only two or four states are sufficient for this purpose, and the decoding cost involved in the trellis part is typically negligible. Both simulation and analytical results are provided to demonstrate the advantages of the proposed scheme. The proposed scheme is of theoretical interest as it can achieve performance of BER=10/sup -5/ at E/sub b//N/sub 0//spl ap/-1.2dB (only about 0.4 dB away from the ultimate low-rate Shannon limit) with an information block size of 65534. To the authors' knowledge, this is the best result achieved to date with respect to the ultimate Shannon limit. With regard to practical issues, the decoding complexity of the proposed code is considerably lower than that of existing low-rate turbo-type codes with comparable performance.     

Growth rate reduction in self-limiting growth of doped GaAs by molecular layer epitaxy

Self-limiting growth of GaAs with doping by molecular layer epitaxy (MLE) has been studied using the intermittent supply of TEG, AsH₃, and a dopant precursor, Te(C₂H₅)₂ (diethyl-tellurium: DETe) for n-type growth on GaAs (0 0 1). The self-limiting monolayer growth is applicable at 265°C, however, the growth rate per cycle of doping decreased and saturated at about 0.4 monolayer with increasing doping concentration. To clarify the mechanism of growth with doping and to solve the problem of the growth rate reduction, a doping cycle followed by several cycles of undoped growth was performed. The growth rate reduction in the TEG–AsH₃ system is due to the electrical characteristics of the growing surface, namely, the exchange reaction of TEG is reduced with increasing doping concentration.     

一种基于QoS的QoE到SLA映射方法

该文提出一种算法IQoE2QoS(Improved QoE to QoS),采用模糊理论的方法计算QoE到QoS的映射。该算法有3重目标：从大量的经验数据中通过计算互信息量方式总结被统计指标之间的关联程度。在大量经验数据的基础上通过多指标模糊判定理论将用户感知映射到应用层用户QoS参数。考虑了用户的QoE和QoS的双向映射,并且阐述了得到的QoE如何自然映射到SLA(Service Level Agreement)。通过仿真表明,IQoE2QoS算法对用户体验的分类准确度是线性回归算法的2到3倍。