基于ZigBee信标模式的无线语音通信研究

ZigBee技术以其低功耗,高网络容量和灵活的自组网能力适合于很多无线通信场景。对ZigBee网络信标模式下,CSMA/CA和GTS两种传输机制分别进行仿真建模,研究在不同语音编码速率时,星型网络能容纳的语音节点数。仿真结果表明:在CSMA/CA方式下,语音编码速率依次为5.15,16和32 kb/s时,ZigBee网络能容纳的节点数分别为8,4和3;在GTS方式下,端节点数超过4时,网络丢包率和吞吐量均优于CSMA/CA,能容纳至多7个端节点同时通信。     

改性含钪薄膜阴极的研究

采用Sc6WO12+W代替传统的Sc2WO3+W材料制备溅射靶,利用三极直流溅射方法制备含钪薄膜阴极。这种方法不需要在覆膜过程中通入氧气或采取其它的复杂氧化工艺,不仅简化了操作也提高了阴极制备的稳定性和一致性。本文研究了这种阴极的发射特性和功函数分布情况。这种阴极在1000℃时能提供86A/cm2的发射电流密度,表现出良好的发射性能。     

新型的基于倾角法海流测量仪的研究与开发

为了在海流测量中更好地使用海流计获取真实的流速和流向信息,设计了一种新型的基于倾角法的海流测量仪。该测量仪采用Atmel公司开发的低功耗、高性能的CMOS型AT89S52单片机,通过串行口与上位机通信,利用VC＋＋6．0友好的设计界面以及Matlab的绘图功能,实现对原始采集数据大容量存储、回放处理功能。海流测量仪操作简单,运行稳定,有较好的应用前景。     

Intense up-conversion emissions of yb3＋/Dy3＋ co-doped A12O3 nanopowders prepared by non-aqueous sol-gel method＊

Yb 3+ /Dy 3+ co-doped Al2O3 nanopowders have been prepared by the non-aqueous sol-gel method and their up- conversion photoluminescence spectra are measured under excitation by a 980-nm semiconductor laser. The results show that there are comparatively abundant spectra of up-conversion emissions centered at 378, 408, 527 and 543, and 663 nm, corresponding to4G9/2 → 6H13/2,4G9/2→6H11/2 ,4I15/2 →6H13/2 , and 4F9/2 → 6H11/2 transitions of Dy 3+ , respectively. Two-photon and three-photon processes are involved in ultraviolet, violet, green, and red up-conversion emissions. The energy transition between Yb3+ and Dy3+ is discussed.     

Painleve Property,Beicklund Transformations and Rouge Wave Solutions of （3 ＋ 1）-Dimensional Burgers Equation

Burgers equation is the simplest one in soliton theory, which has been widely applied in almost all the physical branches. In this paper, we discuss the Painleve property of the （3＋1）-dimensional Burgers equation, and then Becklund transformation is derived according to the truncated expansion of the obtained Painleve analysis. Using the Backlund transformation, we find the rouge wave solutions to the equation via the multilinear variable separation approach. And we aiso give an exact solution obtained by general variable separation approach, which is proved to possess abundant structures.     

NaF晶体中电荷补偿掺杂Ce^3＋离子光谱性质的从头算

用从头算研究NaF晶体中Ce^3＋占据Na＋格位时的光谱性质,电荷补偿由占据格位第一配位壳层的两个氟原子被氧取代 （OF＇） 或第二配位壳层的两个Na空位（Na＇） 来提供. 首先采用基于DFT的超单胞模型方法优化了Ce^3＋的局域结构,并构造以Ce为中心的镶嵌团簇,对其进行基于波函数理论的CASSCF/CASPT2/RASSI-SO计算,获得Ce^3＋的4f1和5d1组态分裂能级能量. 通过将4f→5d跃迁能量计算值与低温实验激发光谱比较,发现实验观测到的最低4f→5d跃迁谱带（390 nm）来自于两个最近邻OF＇补偿的Ce^3＋离子,并不是文献中的两个次近邻VNa＇ 补偿的Ce^3＋. 最后从5d1组态能级重心位移和晶场分裂两方面分析了由两个最近邻OF＇取代造成最低4f→5d 跃迁红移约8000 cm-1的原因.     

Complementary studies on N＊ from e＋e-, pp and pp collisions

Complementary to the conventional experimental studies on N＊ from πN and γ（＊）N reactions, the e＋e-, pp and pp collisions can give novel insights into these N＊ resonances. While the e＋e- collisions through production and decay of vector charmonium ψ provide a nice isospin filter for a simultaneously study of N＊, △＊, ∧＊, ∑＊ and 2＊, the pp collisions should be the best place for producing those △＊＋＋ with large coupling to p＋p though pp →nA＊＋＋ reaction, and the pp collisions should be the best place for looking for those N＊ with large coupling to σN.     

基于VHDL语言的洗衣机控制系统设计

通过洗衣机系统的设计,详细介绍了如何使用硬件描述语言VHDL设计复杂逻辑电路的步骤和过程,以屁应用美国ALTERA公司的MAX＋PLUSII软件进行系统设计及仿真的方法．通过设计,可以看到应用EDA技术进行系统设计、逻辑综合和模块仿真是数字系统设计的重要手段。     

共振瑞利散射光谱法测定人体血浆和尿液中的加替沙星

提出了共振瑞利散射光谱法测定加替沙星的新方法。在pH5.2—5.6的Britton-Robinson缓冲溶液中,加替沙星(Gatifloxacin,GTFX)与钴(Ⅱ)能形成阳离子配合物,它可进一步与酸性染料刚果红(CR)阴离子反应形成2:1:1(GTFX:Co~(2+):CR)的三元离子缔合物,使共振瑞利散射(RRS)急剧增强,其2个散射峰分别位于382nm和560nm处。在382nm处,加替沙星的浓度在0—5.26μg·mL~(-1)范围内,与RRS强度有良好的线性关系,检出限(3σ)为7.5ng·mL~(-1)。此方法简便、快速,且具有良好的选择性,用于片剂、尿液和血浆中加替沙星的测定,其回收率在96.1%—103.6%。     

Monte Carlo generator photon jets used for luminosity at e+e－ colliders

A Monte-Carlo Generator Photon Jets （MCGPJ） to simulate Bhabha scattering as well as production of two charged muons and two photons events is discussed. The theoretical precision of the cross sections with radiative corrections （RC） is estimated to be smaller than 0.2%. The Next Leading Order （NLO） radiative corrections proportional to α are treated exactly, whereas the all logarithmically enhanced contributions, related to photon jets emitted in the collinear region, are taken into account in frame of the Structure Function approach. Numerous tests of the MCGPJ as well as a detailed comparison with other MC generators are presented.