用减压化学气相沉积技术制备应变硅材料

利用减压化学气相沉积技术,制备出应变Si/弛豫Si0.9Ge01/渐变组分弛豫SiGe/Si衬底.通过控制组分渐变SiGe过渡层的组分梯度和适当优化弛豫SiGe层的外延生长工艺,有效地降低了表面粗糙度和位错密度.与Ge组分突变相比,采用线性渐变组分后,应变硅材料表面粗糙度从3.07nm减小到0.75nm,位错密度约为5×104 cm-2,表面应变硅层应变度约为0.45%.     

基于DSP的光电编码器自动检测系统

传统的光电编码器的精度检测利用平行光管和多面体,其缺点是检测时间长,需要有经验的师傅;编码器误码检测则通过旋转编码器,使二进制灯排逐次进位,同样监测效率低,且容易错判。文中设计了一套光电编码器自动检测系统,基准编码器、电机和被检编码器同轴连接,其中24位基准编码器作为精度检测基准和位置反馈元件构成闭环系统,以DSP为核心的控制器控制自动检测系统工作在两种模式下,精度检测工作在位置模式下,错码检测工作在速度模式下,可以检测精度的同时对错码进行判别。采用该系统对两台14位编码器进行检测,实验结果表明精度检测数据与采用平行光管精度检测数据一致。该系统可提高检测效率,缩短编码器设计周期,可以推广到其他型号编码器调试与检测中。     

Synergy of Pickering Emulsion and Sol‐Gel Process for the Construction of an Efficient,Recyclable Enzyme Cascade System

An efficient, easily recyclable enzyme cascade system based on nanoparticle‐stabilized capsules (NPSCs) is constructed through a synergy of a Pickering emulsion and sol‐gel process. Specifically, oligodopa‐coated titania nanoparticles (biomimetic titania) containing the first enzyme (FateDH) are synthesized through a bioadhesion‐assisted biomimetic mineralization approach. The biomimetic titania is then spontaneously assembled at the interface between the oil phase (hexadecane/butyl titanate (BuTi) mixture) and water phase during the formation of Pickering emulsions. The sol‐gel process of BuTi can produce not only butanol for assisting the formation of Pickering emulsions but also titania gel particles (sol‐gel titania) for cross‐linking the biomimetic titania through catechol‐titanium chelating. The NPSCs obtained, which contain the first enzyme, conjugate the second enzyme (FaldDH) onto the surface for constructing the enzyme cascade system. The system exhibits high activity and stability, particularly, superior recyclability for conversion of CO₂ into formaldehyde. In detail, the system shows a formaldehyde yield of 50.0%, and can quickly float onto the air/water interface soon after stopping the agitation of reaction mixtures, which ensures that the formaldehyde yield keeps almost unaltered after 10 times recycling. This study will be useful for facile construction of a wealth of catalytic systems with efficient, recyclable attributes.     

基于TMS320F28335的SVPWM信号发生器

电压空间矢量脉宽调制能提高直流侧电压利用率,其应用范围已跨越变频调速系统,进入各个领域。文中在分析SVPWM原理的基础上,结合三相H桥逆变电路的特点,介绍了TMS320F28335的SVPWM信号发生器设计,并实现了逆变桥一相断路情况下的SVPWM波。通过硬软件结合,在DSP实验平台上进行了调试和实验观察,给出实验结果波形。实验证明,基于DSP的SVPWM信号发生器具有实现简单方便、易于数字化的特点,能更好地满足功率器件对驱动信号的不同要求,便于实现容错控制。     

重性抑郁患者血浆双向电泳图谱的构建

目的：建赢稳定的重性抑郁血浆双向凝胶电泳技术体系。方法：从血浆蛋自质样品制备、等电聚焦和水化方式等方面对双向凝胶电泳分离技术进行优化。结果：建立了稳定的抑郁症血浆双向凝胶电泳图谱,达到了较好的血浆蛋白分离效果。结论：成功的血浆图谱构建,为进一步开展重性抑郁诊断和机制研究奠定基础。     

锇在甲酸体系抛光液中化学机械抛光研究

基于金属锇有可能成为大规模集成电路铜互连扩散阻挡层新材料,利用自制的甲酸(HCOOH)体系抛光液对金属锇进行了化学机械抛光研究,利用原子力显微镜(AFM)观察抛光后锇的表面形貌。采用电化学分析方法研究双氧水(H2O2)、HCOOH和苯丙三氮唑(BTA)对样品腐蚀效果的影响。结果表明:当抛光液中仅含H2O2时,金属锇表面腐蚀不明显;而在H2O2-HCOOH体系中,H2O2浓度的增加可使金属锇表面的腐蚀速度明显加快,但不利于金属锇表面钝化膜的形成;缓蚀剂BTA的加入促进了金属锇表面钝化膜的生成,降低了抛光速率,但同时提高了金属锇的表面质量,表面粗糙度Ra由8.0 nm降低到4.2 nm。     

基于偏振控制技术提高光纤受激布里渊散射慢光稳定性研究

基于对光纤中抽运光束和斯托克斯光束的偏振态控制,提出了一种提高受激布里渊散射(SBS)慢光稳定性的实验方案。通过在保偏光纤两端分别熔接保偏光环行器(快轴阻塞)组成一个慢光单元,确保了光纤中抽运光束和斯托克斯光束具有一致的偏振态(沿保偏光纤慢轴)。建立了基于此慢光单元的SBS慢光实验研究系统,对脉宽为38ns的高斯脉冲获得了0.87ns/dB的时间延迟;相对于不加偏振控管的单模石英光纤而言,该慢光单元系统的布里渊增益因子提高了3倍。研究表明:该方案能有效地提高SBS效应和SBS慢光时延的稳定性。     

基于去噪卷积神经网络的雷达信号调制类型识别

针对低截获概率雷达(LPI)信号处理复杂,低信噪比条件下识别率低的问题,该文提出一种基于去噪卷积神经网络和Inception网络的信号分类识别系统.首先对8种LPI雷达信号进行Choi-Williams分布(CWD)时频变换,得到2维时频图像,然后使用去噪卷积神经网络进行时频图像去噪处理,最后将图像发送到Incepti...     

面向电网业务质量保障的5G高可靠低时延通信资源调度方法

该文研究面向电网业务质量保障的5G 高可靠低时延通信(URLLC)的资源调度机制,以高效利用低频段蜂窝通信系统内有限的频谱和功率资源来兼顾电力终端传输速率和调度时延、调度公平性,保障不同电力业务的通信质量（QoS）。首先,基于URLLC的高可靠低时延传输特性,建立电力终端多小区下行传输模型。然后,提出面向系统下行吞吐量最大化的资源分配问题模型并对其进行分步求解,分别提出基于定价机制与非合作博弈的功率分配算法和基于调度时延要求的改进比例公平算法（DPF）动态调度信道资源。仿真结果表明,提出的资源调度方法能在保证一定传输可靠性和公平性的条件下降低电力终端调度时延,满足不同业务等级的QoS需求,与已知算法对比有一定的优越性。     

H2 In Situ Inducing Strategy on Pt Surface Segregation Over Low Pt Doped PtNi5 Nanoalloy with Superhigh Alkaline HER Activity

Surface segregation constitutes an efficient approach to enhance the alkaline hydrogen evolution reaction (HER) activity of bimetallic Pt_xNi_y nanoalloys. Herein, a new strategy is proposed by utilizing the small gas molecule of H₂ as the structure directing agent (SDA) to in situ induce Pt surface segregations over a series of PtNi₅-n samples with extremely low Pt doping (Pt/Ni = 0.2). Impressively, the sample of PtNi₅-0.3 synthesized under 0.3 MPa H₂ delivers an extremely low overpotential of 26.8 mV (−10 mA cm⁻²) and Tafel slope of 19.2 mV dec⁻¹, which is superior to most of the previously reported Pt_xNi_y electrocatalysts. This is substantially related to the strong H₂ in situ inducing effect to generate Pt-rich@Ni-rich core-shell nanostructure of PtNi₅-0.3 with an ultrahigh Pt surface content of 46%. The specific mechanistic effects of H₂ during the PtNi₅-n synthesis process are well illustrated based on the combined experimental and theoretical studies. The density functional theory mechanism simulations further unravel that the evolved active site of PtNi₅-n can efficiently reduce the reaction Gibbs free energies; especially for the scenario of PtNi₅-0.3, the downward-shifted d band center of the Pt active site significantly reduces the Pt H bond strength, eventually resulting in the lowest absolute value of ΔG_H.