WPAN标准的最新发展

随着通信技术的发展,服务于个人工作区域的无线移动通信技术逐渐成为研究开发的热点.文章介绍了无线个域网(WPAN)标准研究组织的概况,并着重介绍了WPAN标准的最新进展和应用情况.     

基于电子管SRPP电路的高保真耳机放大器设计

以电子管微变等效电路分析为基础,设计了一款以驱动高保真耳机为目的的耳机放大器.该放大器以共阴极放大器为输入级,SRPP放大器为输出级,驱动耳机工作.分析了该放大器的开环和闭环参数,并采用客观测量和主观评价的方式对该放大器的品质进行评价.     

Antibacterial Activity of Aureonuclemycin Produced by Streptomyces aureus Strain SPRI-371

Actinomycetes play a vital role as one of the most important natural resources for both pharmaceutical and agricultural applications. The actinomycete strain SPRI-371, isolated from soil collected in Jiangsu province, China, was classified as Streptomyces aureus based on its morphological, physiological, biochemical and molecular biological characteristics. Its bacterial activity metabolites were identified as aureonuclemycin (ANM), belonging to adenosine derivatives with the molecular formula C₁₆H₁₉N₅O₉ for ANM A and C₁₀H₁₃N₅O₃ for ANM B. Simultaneously, the industrial fermentation process of a mutated S. aureus strain SPRI-371 was optimized in a 20 m³ fermentation tank, featuring a rotation speed of 170 rpm, a pressure of 0.05 MPa, an inoculum age of 36–40 h and a dissolved oxygen level maintained at 1–30% within 40–80 h and at >60% in the later period, resulting in an ANM yield of >3700 mg/L. In the industrial separation of fermentation broth, the sulfuric acid solution was selected to adjust pH and 4# resin was used for adsorption. Then, it was resolved with 20% ethanol solution and concentrated in a vacuum (60–65 °C), with excellent results. Antibacterial experiments showed that ANM was less active or inactive against Xanthomonas oryzae pv. oryzae, Xanthomonas citri subsp. citri and Xanthomonas oryzae pv. oryzicola and most bacteria, yeast and fungi in vitro. However, in vivo experiments showed that ANM exhibited extremely significant protective and therapeutic activity against diseases caused by X. oryzae pv. oryzae and X. oryzae pv. oryzicola in rice and X. citri in oranges and lemons. In field trials, ANM A 150 gai/ha + ANM B 75 gai/ha exhibited excellent therapeutic activity against rice bacterial leaf blight, citrus canker and rice bacterial leaf streak. Furthermore, as the dosage and production cost of ANM are lower than those of commercial drugs, it has good application prospects.     

太阳能半导体空调制冷装置模块化实验研究

建立了以水为热交换媒介的太阳能热电模块制冷实验系统.系统配置了双位能量存储装置,用以储存昼夜温差能和太阳光电转换电能,以备无日照或日照不足时系统能够连续工作.热电制冷装置模块化,用以适应制冷功率变化较大的空间制冷,并在制冷启动与温度维持不同阶段实现较大功率的切入或撤出.制冷模块以半导体热电元件为核心,冷热端均以导热性能良好的紫铜作为热交换材料,以热容量较大的水作为冷却液和散热循环液.热交换装置采取集合散热冷却分流的集散一体化热交换系统.对制冷模块制冷性能进行了实验分析,并对制冷效果进行了模拟实验,实验结果基本达到了设计的预期.     

多量子阱垂直腔面发射半导体激光器的速率方程分析

依据多量子阱垂直腔面发射半导体激光器（ＶＣＳＥＬＳ）的结构特点,并考虑到腔量子电动力学中自发辐射增强效应,建立了多量子阱ＶＣＳＥＬＳ的速率方程,并给出了其方程的严格解析解,在此基础之上,讨论了ＶＣＳＥＬＳ的稳态特性,并与普通开腔和三维封闭腔中的结果进行了比较,给出了Ｖ     

Spin transport properties in double quantum rings connected in series

A new model of metal/semiconductor/metal double-quantum-ring connected in series is proposed and the transport properties in this model are theoretically studied.The results imply that the transmission coefficient shows periodic variations with increasing semiconductor ring size.The effects of the magnetic field and Rashba spin-orbit interaction on the transmission coefficient for two kinds of spin state electrons are different.The number of the transmission coefficient peaks is related to the length ratio between the upper arm and the half circumference of the ring.In addition,the transmission coefficient shows oscillation behavior with enhanced external magnetic field,and the corresponding average value is related to the two leads’ relative position.     

低缺陷密度和平整表面的硅基砷化镓外延

Device-quality GaAs thin films have been grown on miscut Ge-on-Si substrates by metal-organic chemical vapor deposition. A method of two-step epitaxy of GaAs is performed to achieve a high-quality top-layer. The initial thin buffer layer at 360 ℃ is critical for the suppression of anti-phase boundaries and threading dislocations. The etch pit density ofGaAs epilayers by KOH etching could reach 2.25 × 10^5 cm^-2 and high-quality GaAs top epilayers are observed by transmission electron microscopy. The band-to-band photoluminescence property of GaAs epilayers on different substrates is also investigated and negative band shifts of several to tens of meVs are found because of tensile strains in the GaAs epilayers. To achieve a smooth surface, a polishing process is performed, followed by a second epitaxy of GaAs. The root-mean-square roughness of the GaAs surface could be less than 1 nm, which is comparable with that of homo-epitaxial GaAs. These low-defect and smooth GaAs epilayers on Si are desirable for GaAs-based devices on silicon substrates.     

运营商大数据平台的敏感信息保护研究

探讨了运营商大数据平台的敏感信息范围,给出了敏感信息保护的方法步骤,总结了该研究领域内的关键技术及每类技术的主流技术方法,并针对实际的运营商大数据平台的分层架构,设计了不同敏感信息保护技术的技术实现方案.     

TD—SCDMA移动终端智能天线技术的算法实现

智能天线技术是第三代移动通信标准TD-SCDMA的标志性技术,是TD—SCDMA标准相对于其他标准的最大区别和优势,具有增加系统容量、扩大系统覆盖范围、络逐渐商用,智能天线技术也愈加成熟。本文阐述了TD势,并通过DSP和FPGA分别实现了自适应算法。改善服务质量等一系列优点。随着TD-SCDMA网SCDMA移动终端智能天线的一些知识及相关的优     

一种用于脉冲式超宽带接收机的低抖动，低杂散多相输出锁相环

本文提出了一种用于脉冲式超宽带接收机的低抖动,低杂散多相输出锁相环。为了同时满足低抖动、低功耗和输出多相时钟这些需求,该锁相环基于一个环形振荡器结构。为了提高多相时钟的时间精度和相位噪声性能,设计了一个改善了噪声和匹配特性的压控振荡器。在设计中,通过良好的匹配电荷泵和仔细选择环路滤波器带宽来抑制参考频率杂散。测试结果表明,当载波频率为264 MHz时,1 MHz失调频率下的相位噪声为-118.42 dBc/Hz,均方根抖动为1.53 ps,参考频率杂散为-66.81 dBc。该芯片采用0.13 µm CMOS工艺制造,1.2 V电源电压下功耗为4.23 mW,占用0.14 mm2的面积。