镍离子与丙酮,丁酮分子的气相反应

用一种结合激光解离和时间飞行质谱仪的方法去研究金属离子与有机分子的气相反应。研究了金属镍离子与丙酮和丁酮分子的气相反应，并讨论了其反应机理。     

气相反应法合成精细AIN粉末

<正> AlN陶瓷有很高的热导性和电阻率,可用作半导体器件的陶瓷基片。工业上合成AlN粉主要采用Al_2O_3热碳还原法。这是一种成批生产的方法,不利于连续生产。用气相反应法可制备出高纯度AlN粉,且适于连续生产。笔者研究了用AlCl_3和NH_3气进行气相反应来合成AlN粉的方法。     

BaO－P_2O_5和R_2O－BaO－P_2O_5系统磷酸盐激光玻璃RAP法除

研究了熔炼温度和气相反应剂（ＣＣｌ４，ＳＯＣｌ２和ＰＯＣｌ３）对ＢａＯ－Ｐ２Ｏ５（Ｎ２１）和Ｒ２Ｏ－ＢａＯ－Ｐ２Ｏ５（ＨＬＣ－５）系统磷酸盐激光玻璃ＲＡＰ法除水速率的影响．讨论了Ｎ２１和ＨＬＣ－５型玻璃中Ｎｄ３＋的荧光寿命与ＯＨ基含量的关系，井对除水前后玻璃的激光性能和物理性质进行了比较。     

分子通信研究综述

基于生物启发的分子通信是一种以生物化学分子作为信息载体、用于互联纳米机器以组成分布式纳米网络的通信技术。归纳了分子通信的定义和特性,以及基于分子通信纳米网络的应用领域和国内外相关领域的重要科研活动与项目;介绍了分子通信的系统结构,其中重点描述了信息分子的传输机制;分别从系统的设计与实现、理论研究和基于分子通信的纳米网络技术3个方向总结和分析了分子通信的研究与发展现状,并展望了未来的研究方向。     

脉冲CO_2激光制备纳米级SiC粉末

采用脉冲ＴＥＡＣＯ２激光诱发ＳＩＨ４＋ＣＨ４等离子体化学气相反应，合成了粒度分布均匀的纳米ＳｉＣ球型陶瓷粉末，采用傅里叶红外光谱、Ｘ射线衍射、元素分析、透射电子显微镜等多种技术对粉末性能进行了分析，利用光学发射谱技术对反应过程进行了初步研究。     

其他激光应用

用TEA CO_2激光诱导四甲基硅烷(TMS)的气相反应,合成了亚微米碳化硅超细粉。基态的TMS并不直接吸收CO_2激光,但可在激光     

激光法合成SiC粉末的机理研究

激光法合成ＳｉＣ粉末的机理研究韩理，于威，傅广生，张连水（河北大学物理系，保定０７１００２）采用强脉冲激光诱发等离子体化学反应制备固态材料是近几年发展起来的激光应用技术。本工作利用脉冲ＴＥＡＣＯＺ激光诱发ＳｉＨ４＋ＣＨ４等离子体气相反应合成了纳米级Ｓ...     

DNA分子操纵与分子电子学

简要介绍了DNA分子研究的进展,包括DNA分子的导电性、DNA分子器件、DNA分子与外界的连接、DNA分子操纵技术及DNA分子和纳米碳管的比较,并展望了DNA分子电子学及相关领域的发展趋势。     

MOCVD生产GaN气相、表面反应的数值模拟

采用计算流体力学方法对生长GaN的立式行星结构金属有机物化学气相沉积(MOCVD)反应室中的流场、空间气相反应和载片表面沉积速率进行了三维数值模拟,研究了载片旋转、反应室高度、氨气流量和基座不同温度布局方式对反应产物浓度分布和载片表面沉积速率等物理参数的影响,并对主要运行参数提出了优化建议,例如采用较低反应室高度、基座中心附近采用较低温度等.     

MOCVD生产GaN气相、表面反应的数值模拟

采用计算流体力学方法对生长GaN的立式行星结构金属有机物化学气相沉积(MOCVD)反应室中的流场、空间气相反应和载片表面沉积速率进行了三维数值模拟,研究了载片旋转、反应室高度、氨气流量和基座不同温度布局方式对反应产物浓度分布和载片表面沉积速率等物理参数的影响,并对主要运行参数提出了优化建议,例如采用较低反应室高度、基座中心附近采用较低温度等.     

无功功率教学新探

本文试图提出一种无功功率的教学方法,使无功功率的定义、物理解释与有功功率保持逻辑上的一致,同时也使无功功率与其它功率概念的联系变得清晰明确。我们在教学中,首先定义旋转电流相量,然后将其与瞬时电压相乘得到复数瞬时功率,最后由复数瞬时功率在一个周期内的平均值即得到无功功率的定义。本教学方法的优势在于:新的无功功率定义在形式上与有功功率统一,与现行无功功率的教学内容没有冲突,且更强调无功功率的功率含义。     

Analysis of reactive jamming against satellite communications

In this paper, we analyze the feasibility of reactive jamming in a satellite communications scenario and propose a countermeasure that takes advantage of the constraints associated with reactive jamming. A reactive jammer is a type of jammer that has the ability to sense a portion of spectrum and immediately transmit a jamming signal when it senses a signal it wants to jam. Thus, a reactive jammer can counter the processing gain associated with frequency hopping spread spectrum. This paper provides a three‐step approach to analyzing the primary constraints associated with reactive jamming, as well as detailed example scenarios (both theoretical and simulated) that demonstrate the feasibility analysis. Additional clarity is provided by splitting the analysis into uplink and downlink jamming. A strategy to mitigate the effects of reactive jamming is presented, which takes advantage of the geometric constraints of reactive jamming by using a coding and interleaving scheme that results in the transmitted bits appearing at the very beginning of each hop. This work demonstrates that reactive jamming is a valid threat to satellite communication systems. The analysis and simulation results suggest that as long as the geographical area around user terminals is free of reactive jammers, substantial mitigation can be achieved using the proposed mitigation strategy. Copyright © 2015 John Wiley & Sons, Ltd.     

间歇式能源发电系统无功补偿技术的研究

针对间歇式能源发电系统的特点和无功需求,提出了将无功补偿与风力并网发电相结合的设计方案,通过计算得出了间歇式能源发电系统中电缆和变压器无功损耗.本文利用Mat-lab/Simulink搭建了具有无功补偿功能的并网变流器的仿真模型,并采用有功无功解耦控制和SPWM控制方法,补偿系统所需无功以及有效抑制动态电压波动.最后,仿真结果验证了风力并网变流器在向电网提供有功功率的同时也能够提供一定容量的无功功率,提高系统功率因数,有效抑制电网电压波动.     

Harmonic and reactive power compensation based on the generalizedinstantaneous reactive power theory for three-phase four-wire systems

This paper presents harmonic and reactive power compensation based on a generalized theory of instantaneous reactive power for three-phase power systems. This new theory gives a generalized definition of instantaneous reactive power, which is valid for sinusoidal or nonsinusoidal and balanced or unbalanced three-phase power systems with or without zero-sequence currents and/or voltages. The properties and physical meanings of the newly defined instantaneous reactive power are discussed in detail. A harmonic and reactive power compensator based on the new theory for a three-phase harmonic-distorted power system with zero-sequence components in the load current and/or source voltage is then used as an example to show harmonic and reactive power measurement and compensation using the new theory. Simulation and experimental results are presented     

Ni－Al系粉末压坯激光反应烧结初步研究

对Ni－Al系粉末压坯激光反应烧结的初步研究表明,利用激光反应烧结能够弥补一般激光烧结受试样尺寸的限制。并因其点火时间短、反应层层递进、扩展等特点,使得烧结后试样整体组织和性能均匀,且易得到刚状结构和理想的产物。     

基于瞬时无功功率理论的谐波和无功电流检测

介绍了基于瞬时无功功率的谐波和无功电流实时检测理论。该理论突破了传统的平均值功率定义,系统的定义了瞬时无功功率、瞬时有功功率。可实时的检测电力系统中的谐波和无功电流。讨论了瞬时无功功率理论,得出基于瞬时无功功率理论的谐波和无功电流检测算法。结果表明,这种检测法能为抑制谐波和无功补偿提供可靠的谐波及无功分量。     

基于低通滤波器的含有非正弦无功功率的计量

目前对非正弦无功电能计量的研究还很不完善。为了能够准确地理解和计算非正弦电路的无功功率,导出了非正弦电路的无功功率的计算公式,分析了公式中每一项的物理意义,并提出了一种基于低通滤波器的含有非线性无功功率的计量方法。依据IEC1268标准的技术条件给出了两种无功测试方法测量误差的试验数据,从而得出了低通滤波器方法测量无功功率是一种较好的方法的结论。     

In Situ Exfoliated,N‐Doped,and Edge‐Rich Ultrathin Layered Double Hydroxides Nanosheets for Oxygen Evolution Reaction

The number of catalytically reactive sites and their intrinsic electrocatalytic activity strongly affect the performance of electrocatalysts. Recently, there are growing concerns about layered double hydroxides (LDHs) for oxygen evolution reaction (OER). Exfoliating LDHs is an effective method to increase the reactive sites, however, a traditional liquid phase exfoliation method is usually very labor‐intensive and time‐consuming. On the other hand, proper heteroelement doping and edge engineering are helpful to tune the intrinsic activity of reactive sites. In this work, bulk CoFe LDHs are successfully exfoliated into ultrathin CoFe LDHs nanosheets by nitrogen plasma. Meanwhile, nitrogen doping and defects are introduced into exfoliated ultrathin CoFe LDHs nanosheets. The number of reactive sites can be increased efficiently by the formation of ultrathin CoFe LDHs nanosheets, the nitrogen dopant alters the surrounding electronic arrangement of reactive site facilitating the adsorption of OER intermediates, and the electrocatalytic activity of reactive sites can be further tuned efficiently by introducing defects which increase the number of dangling bonds neighboring reactive sites and decrease the coordination number of reactive sites. With these advantages, this electrocatalyst shows excellent OER activity with an ultralow overpotential of 233 mV at 10 mA cm^?2.     

基于PWM的无功补偿系统设计

随着功率因数低的工业用电设备接入电网中,对电力系统运行稳定性和电压质量提出了更高的要求。文中基于无功补偿的原理,并设计了PWM连续调容的动态无功补偿系统,该系统克服了传统无功补偿器用感性无功覆盖容性无功,以产生可调容性无功的调节方式存在的不足,改进了现有无功补偿系统只能分组分级投切,不能连续调容的现状。能够快速跟踪负载变化,实时补偿无功功率,稳定电网电压,提高功率因数。     

基于单片机控制的低压无功补偿装置的设计

通过对低压端无功补偿问题的分析,结合传统补偿方式的优点,并针对我校部分教学楼供电系统功率因数较低的问题,提出了采用单片机控制的无功补偿改造方案,实施补偿后该系统运行情况良好。