微波组件典型质量问题分析及对策

总结目前微波组件生产的特点,通过对微波组件生产中典型质量问题的案例剖析,论述微波组件质量问题具有的滞后性和隐蔽性的特征,分析主要失效模式及失效机理,从产品设计、工艺过程控制、元器件质量等方面对影响产品质量的因素进行探讨,并在技术方法上提出具体的解决对策.     

阴极荧光联合分析系统在Ⅲ族氮化物研究中的应用

利用高性能阴极荧光(CL)联合分析系统对几类典型的Ⅲ族氮化物材料进行测试分析.在光谱研究中,利用CL紫外町见光谱系统,对c面蓝宝石衬底上生长的AlxGa1-xN薄膜进行阴极荧光单色谱测试分析,揭示了CL的激发强度与发光带之间的变化关系.进一步研究了掺Mg的Al0.5Ga0.5N薄膜的带边和杂质能级发光机理.利用CL近红外光谱系统对InN薄膜的阴极发光特性进行了研究,验证了InN实际光学带边E8在0.77eV附近.利用微区分析(CL mapping)系统,可在紫外波段确切地给出材料不同波长的荧光发光区这一特点,对HVPE生长的自支撑GaN衬底进行了SEM和CL微区的对比分析,研究了GaN的位错类型和分布.     

人工股骨头置换术治疗高龄股骨转子下骨折

转子下骨折的高龄患者,常合并多种基础性疾病,如采用内固定治疗,患者一般需卧床5至8周才能扶拐部分负重行走,仍易产生坠积性肺炎、褥疮、泌尿系感染、深静脉血栓等严重并发症。本文探讨运用人工半髋关节置换术治疗高龄患者股骨转子下骨折,旨在实现让患者早期下床功能锻炼,减少长期卧床并发症的目的。     

Dopant-Free Hole Transport Materials Based on a Large Conjugated Electron-Deficient Core for Efficient Perovskite Solar Cells

Hole transport materials (HTMs) play a significant role in device efficiencies and long-term stabilities of perovskite solar cells (PSCs). In this work, two simple dopant-free HTMs are designed with a large conjugated electron-deficient core. On the one hand, a large coplanar backbone endows enhanced π–π stacking and reduced hole hopping distance. On the other hand, the incorporation of electron-deficient unit can easily tune the energy levels as well as increase hole mobilities. Combining these two advantages together, 12,13-bis(2-ethylhexyl)-3,9-diundecyl-12,13-dihydro[1,2,5]thiadiazole[3,4-e]thieno[2″,3″:4,5]thieno[2′,3′:4,5]pyrrolo[3,2-g]thieno[2′,3′:4,5]thieno[3,2-b]indole is chosen as the large electron-deficient core to construct two novel dopant-free HTMs, Y6-T and Y-T. Both Y6-T and Y-T behave suitable highest occupied molecular orbital levels, good hole mobilities, as well as strong hydrophobicities. After careful device optimization with a passivation agent, Y-T delivers an impressive power conversion efficiency of 20.29%, which is higher than that of Y6-T (18.82%) and doped spiro-OMeTAD (19.24%). Moreover, PSCs based on Y6-T and Y-T show much better long-term stabilities than spiro-OMeTAD due to the intrinsic hydrophobicity. Therefore, this work provides a promising candidate as well as a useful design strategy for exploring dopant-free HTMs, which may pave the way for the commercialization of PSCs.     

超声共沉淀法合成锂离子电池正极材料

采用超声共沉淀法,合成尖晶石型掺杂锰酸锂Li1.05Co0.10Ni0.10Mn1.80O4前驱体,并使用三段热处理方式,制备出尖晶石产物。用粒度分布、XRD、SEM、EDS及电化学性能测试等对其进行表征。结果表明:与未处理试样相比,超声共沉淀法制备的产物的粒度分布变窄,体积比表面积由7.0116m2/cm3缩小至6.9789m2/cm3,晶格常数从0.822nm缩小至0.821nm,晶粒尺寸从67.41nm减小至57.78nm,晶形更加完整,颗粒均匀性更好。经装配成电池测定电化学性能,其充放电平台增长,比容量加大,循环性能更优越。     

基于CAN总线智能查线仪的设计与实现

提出了一种基于CAN总线的智能查线仪的设计和实现方案。将现场可编程芯片、AVR微处理器用于查线设备,使用CAN总线与计算机通信方式来实现各查线模块间的数据通信和结构连接,并通过软件设计来识别有大数量待测端子情况下所需硬件上查线模块的扩充和指定待测查线端点数量,有效地解决了以往各类查线设备缺乏灵活性、扩展性差的问题,能够适应多种场合的不同需求,为各种线缆电气连接关系的检查提供了一种新的解决方案。     

一种基于误差系统稳定性的混沌广义同步方法

该文在将混沌系统分为线性与非线性两部分的基础上,利用反馈控制及参数变换,提出了一种新的混沌广义同步方法。该方法基于线性变换,把系统广义同步问题转化为同步误差系统的稳定性问题,并给出了广义同步存在的条件。该方法可以通过配置同步速度,改善混沌广义同步的性能。且不受混沌系统线性部分稳定性的限制,扩大了混沌广义同步的通用性。通过对Lorenz系统进行仿真,结果表明该方法具有很好的适用性。     

Simulation of Active-Matrix Electrophoretic Display Response Time Optimization by Dual-Gate a-Si:H TFT With a Common Gate Structure

Large off-state drain-source current of the thin-film transistor (TFT) in active-matrix electrophoretic display (AMEPD) pixel leads to dramatic data voltage degradation, which causes severe crosstalk and undesired large response time. In this paper, the leakage current influence on response time is investigated and simulated. A compact model of response time t versus off-state drain-source current I _off is established. The simulation result induces that by reducing I _off the response time can be efficiently shorted. In order to reduce the off-state current, dual-gate amorphous silicon (a-Si:H) TFT with a common gate structure is discussed. Its current regulation mechanism is illustrated, and its fitness for driving the AMEPD pixel is explained. The SPICE simulation results prove that except reducing the crosstalk, dual-gate a-Si TFT can also significantly short the response time by cutting down the off-state current under the operation conditions of AMEPD application, while insignificantly reduces the on-state current.     

二维非线性时域有限差分法分析微孔激光器出射光的近场特性

微孔激光器(VSAL)作为应用于近场光存储系统中的一种新型光源,它的出射光斑的近场特性对于近场光存储是十分重要的。运用二维非线性时域有限差分法(2D-NL-FDTD)分析VSAL出射端即微孔金属膜的近场光学性质,模拟计算了不同参数的微孔金属膜的光强近场分布,对所得结果加以分析,从光学性质的角度,讨论其在近场光存储中的应用,并给出反映其近场光学特性的相关数据。     

UPTIME: an IMS-based mobility framework for next generation mobile networks

Seamless inter-technology mobility is one of the fundamental requirements of next generation mobile networks. For seamless mobility, handover delay and packet loss should be minimized. However, existing solutions suffer from a number of shortcomings in satisfying these requirements: first, handover preparation schemes fail to minimize the handover delay as much as possible. Second, minimizing packet loss which is usually using soft handover (SHO) schemes are excessively wasteful of scarce resources. In this paper, we propose the uninterrupted proactive connection transfer for IMS mobility enhancement (UPTIME) mobility framework which achieves seamless mobility while minimizing excessive power and radio resource consumption. UPTIME incorporates two mechanisms; a proactive handover preparation method and an optimized SHO technique for handover execution. We demonstrate the benefits of the proposed framework through both analysis and simulation. Our simulation results for typical LTE/WiMAX handovers show that the handover preparation delay can be reduced by 70 %, and good packet loss performance can be achieved whilst saving 43 % of radio resources and 48 % of battery power.