A novel method of preparation-adsorption desulfurization process for dibenzothiophene over sawdust-derived nickel/activated carbon

In this work we proposed a novel preparation-adsorption desulfurization method for dibenzothiophene over sawdust-derived nickel/activated carbon prepared by 400°C one step carbonization-activation-modified process. The adsorbent was characterized by X-ray Diffraction (XRD), Boehm titration method, Scanning Electron Microscope (SEM) and N₂ adsorption-desorption technology. The result show that 30% HNO₃ aqueous solution and calcination 2 h for the 30%-NiO/AC adsorbent trend to better desulfurization performance with NiO active adsorption sites and surface oxygen-containing functional groups. After high temperature adsorption desulfurization, the sawdust-derived nickel/activated carbon occurred activation and reaming again, both the specific surface and the microspore volume have been great changed.     

Polyoxometalate-based silica-supported ionic liquids for heterogeneous oxidative desulfurization in fuels

With the aim of deep desulfurization, silica-supported polyoxometalate-based ionic liquids were successfully prepared by a one-pot hydrothermal process and employed in heterogeneous oxidative desulfurization of various sulfur compounds. The compositions and structures of the hybrid samples were characterized by various methods such as FT-IR, XPS, Raman,UV–Vis, wide-angle XRD and N_2 adsorption–desorption. The experimental results indicated that the hybrid materials presented a high dispersion of tungsten species and excellent catalytic activity for the removal of 4,6-dimethyldibenzothiophene without any organic solvent as extractant, and the sulfur removal could reach 100.0% under mild conditions.The catalytic performance on various substrates was also investigated in detail. After cycling seven cycles, the sulfur removal of the heterogeneous system still reached 93.0%. The GC-MS analysis results demonstrated that the sulfur compound was first adsorbed by the catalyst and subsequently oxidized to its corresponding sulfone.     

一个过采样增量－总和调制器的设计与实现

本文设计实现了一个高精度的双通道过采样Ａ／Ｄ电路，它采用由两个二阶调制器级联实现的四阶增量－总和调制器结构，并通过优化调制器内部各级增益，在改善过采样Ａ／Ｄ的大信号过载特性的同时提高其最大输出信嗓比．为降低数字开关噪声对过采样Ａ／Ｄ性能的影响，本文采用了一种低噪声电流控制逻辑设计数字电路．实验芯片的测试结果表明，在６４倍的过采样率下，电流控制逻辑通道和静态ＣＭＯＳ逻辑通道分别获得了９１ｄＢ和８４．５ｄＢ的输出动态范围．     

对一种新型代理签名方案的分析与改进

Gu-Zhang-Yang(2005)提出了一个不需要可信第三方参与的匿名代理签名方案,由于该方案的签名验证数据中没有回避孤悬因子这一现象,因此并不满足强不可伪造性,原始签名人可以伪造一个有效的代理签名通过验证,并成功地在代理签名者身份揭示阶段向公众证明该伪造的代理签名是由合法的代理签名者产生的。本文在分析该方案安全性的基础上提出了改进的匿名代理签名方案,克服了原方案的不足。     

不断探索中的电子战——电子战技术与装备的发展

简述了电子战的发展概况及其在现代信息战中的重要地位和作用,着重介绍了在未来电子战中所应用的两大关键技术,即电子侦察和电子进攻。通过分析目前外军电子侦察和电子进攻在技术、装备方面的升级改进情况及未来电子战系统的发展趋势,提出了我方电子战建设的对策措施。从高新技术、作战理念入手,在作战方式上进行全新的调整和转型,以适应未来电子战的高要求,从而全面提高对敌的纵深打击能力,为打赢信息化战争奠定坚实基础。     

光探测器芯片小信号等效电路模型的建立

提出了一种光探测器芯片小信号等效电路模型及其建立方法.首先根据光探测器的物理结构确定其等效电路模型,模型考虑了影响光探测器高频性能的主要因素.然后精确测量了光探测器芯片的S参数,通过遗传算法对测量的S参数进行拟合,最终计算出模型的各个参量.在130MHz～20GHz范围内的实验结果表明,模型仿真结果与测量结果相吻合,证明了建模方法的可靠性.该模型有效地模拟了光探测器芯片的高频特性,利用该模型可以对光探测器及相应光电集成器件进行电路级仿真和优化.     

GaN HEMT开关器件小信号模型

GaN高电子迁移率晶体管(HEMT)开关器件模型的研究对提高电路性能和缩短研发周期有着重要的意义.为了开发更加精确的电路模型,基于AlGaN/GaN HEMT开关器件的物理结构得到其等效电路模型.利用不同的方法提取开关器件的寄生电容、寄生电感以及寄生电阻.对于栅极附加有千欧姆量级偏置电阻的开关器件提出了一种新的本征参数提取方法.最后通过引入误差因子来评估该模型的准确性和应用在单刀双掷(SPDT)开关电路中检验模型的正确性.结果表明,误差因子E11 =E22＜2.96％,E12 =E21 ＜1.27％,开关电路拟合S参数与实测S参数结果基本吻合.所设计的小信号模型对未来GaN基电路设计提供了一定的理论指导.     

多用户多载波无线携能通信系统的上下行联合资源分配

无线携能通信(SWIPT)技术是解决无线网络能量受限问题的有效方法,该文研究一个由基站(BS)和多用户组成的多载波SWIPT系统,其上行和下行链路均采用正交频分复用(OFDM)技术。在下行链路中,基站向用户同时进行信息与能量传输;在上行链路中,用户利用从基站接收的能量向基站回传信息。该文以最大化上下行加权和速率为目标,联合优化上行和下行的子载波分配和功率分配,提出基于拉格朗日对偶法和椭球法的最优联合资源分配算法。计算机仿真结果证实了该算法的有效性。     

Fabrication of thick, high-quality strained SiGe layer on ultra-thin silicon-on-insulator and modeling of film strain

Fabrication of a thick strained SiGe layer on bulk silicon is hampered by the lattice mismatch and difference in the thermal expansion coefficients between Si and SiGe, and a high Ge content leads to severe strain in the SiGe film. When the thickness of the SiGe film is above a critical value (90 nm for 18% Ge), drastic deterioration of the film properties as well as dislocations will result. In comparison, a silicon-on-insulator (SOI) substrate with a thin top Si layer can mitigate the problems and so a thick SiGe layer with high Ge concentration can conceivably be synthesized. In the work reported here, a 110 nm thick high-quality strained Si_0.82Ge_0.18 layer was fabricated on an ultra-thin SOI substrate with a 30 nm top silicon layer using ultra-high vacuum chemical vapor deposition (UHVCVD). The thickness of the SiGe layer is larger than the critical thickness on bulk Si. Cross-sectional transmission electron microscopy (XTEM) reveals that the SiGe layer is dislocation-free and the atoms at the SiGe/Si interface are well aligned, even though X-ray diffraction (XRD) data indicate that the SiGe film is highly strained. The strain factors determined from the XRD and Raman results agree well.     

利用背面曝光技术制造大高宽比SU8结构的一种新方法

提出了一种解决大高宽比SU8结构的新方法.该方法是将SU8胶涂在一块掩模上,紫外光从掩模的背面照射,这样SU8胶的曝光将从底部开始,不需要进行过曝光来保证底部胶的曝光剂量,从而很容易控制曝光剂量和SU8胶结构的内应力.实验结果表明,该方法能够得到高宽比为32的SU8结构,而文献报道的SU8胶结构的高宽比最大仅为18.