云存储技术及其应用研究

云计算是一种新的网络应用模式,云存储是一个以数据存储和管理为核心的云计算系统。阐述云计算与云存储的原理及应用特点,设计一种基于云存储的高校智慧教学环境——云教学平台,分析该平台的原理、特点等。     

The Influences of DMF Content in Composite Polymer Electrolytes on Li+-Conductivity and Interfacial Stability with Li-Metal

Trace N, N-dimethylformamide(DMF) containing composite polymer electrolytes (CPEs) has attracted much attention owing to the dramatically increased Li⁺-conductivity. But the amount of DMF is critical and needs to be clarified for the interfacial stability, since DMF is easily reduced by Li-metal. Herein, the influences of DMF in poly(ethylene oxide) (PEO) and poly(vinylidene fluoride) (PVDF) based CPEs are studied on the Li⁺-conductivity and interfacial stability. In PEO-based CPEs, owing to a stronger interaction of lithium bis(trifluoromethanesulfon)imide (LiTFSI) with PEO than DMF, DMF can not be confined and be easily evaporated off. Only ≈0.25wt.% DMF is absorbed on ceramic electrolyte fillers, giving two times increased Li⁺-conductivity compared with the DMF-free counterparts and generating stable interface with Li-metal; but over much DMF (≥2.2 wt.%) leads to serious interfacial reactions with Li-metal. While in PVDF-based CPEs, ≈8wt.% DMF is confined by LiTFSI owing to a stronger interaction of LiTFSI with DMF than with PVDF. Short-term stable interface with Li-metal can be obtained, but longer-term cycling or higher current density leads to the gradually aggravated reactions with Li-metal. Thanks to the high-voltage stability of PVDF based CPEs, better cycling performance is obtained when they are used as catholytes to match high-voltage cathodes.     

弹体撞击作用下平纹织物的动态响应分析

利用LS-DYNA有限元软件模拟弹体撞击作用下平纹织物的动态过程,分析织物断裂前的变形特性以及能量吸收特性,讨论边界约束条件和弹体形状对织物动态响应的影响。结果表明:纱线应变能和纱线动能是弹体动能转变的最主要形式,在给定计算的时间内,对于四边无约束、对边固定约束和四边固定约束3种边界条件,不论弹头形状采用平头、半球头和卵形头中的哪一种,两者之和占弹体动能损失量的比例不小于74.6%。模拟结果还表明,边界约束条件和弹体形状对织物的变形、应力分布以及能量吸收特性均有明显影响。边界条件不同,纱线动能和纱线应变能占弹体动能损失量的比例会发生较大变化,织物的能量吸收特性也不同。弹体头部形状不同,受撞击区影响的纱线数目也不同,弹头越钝,织物中抽拔出的纱线数目越多。从织物结构的抗弹性能角度看,织物结构抗钝头弹体的穿透能力要优于尖头弹体。     

An automatic parameter extraction technique for advanced CMOS device modeling using genetic algorithm

We in this paper present an computational intelligence technique to extract semiconductor device model parameters. This solution methodology is based on a genetic algorithm (GA) with an exponential type weight function, renew operator, and adaptive sampling scheme. The proposed approach automatically extracts a set of complete parameters with respect to a specified compact model, such as a BSIM model for deep-submicron and nanoscale complementary metal-oxide-semiconductor (CMOS) devices. Compared with conventional artificial step-by-step fitting approaches, the proposed extraction methodology automatically tracks the shape variation of current-voltage (I-V) curves and examines the first derivative of I-V curves; therefore, highly accurate results can be obtained directly. Applying the renew operator will keep the evolutionary trend improving by removing the individuals without mainly features. The sampling strategy will speed up the evolution process and still maintain the extraction accuracy in a reasonable range. A developed prototype is successfully applied to extract model parameter of N- and P-metal-oxide-semiconductor field effect transistors (MOSFETs). This optimization method shows good physical accuracy and computational performance, and provides an alternative for optimal device modeling and circuit design in nanodevice era. Genetic algorithm based automatic model parameter extraction bridges the communities between circuit design and chip fabrication; in particular, it will significantly benefits design of system-on-a-chip.     

Hole transfer from PbS nanocrystal quantum dots to polymers and efficient hybrid solar cells utilizing infrared photons

Polymer/inorganic-nanocrystals bulk heterojunction solar cells, where inorganic semiconductor nanocrystals such as CdSe, CdS, CdTe, ZnO, TiO₂, and silicon, replace the fullerene molecules as the electron acceptors, typically exhibit a power conversion efficiency (PCE) below 3% even after tremendous engineering efforts to optimize the nanocrystal size, shape, and nanoscale morphology. One promising feature of polymer hybrid solar cells is the ability to sensitize conjugated polymers, which on their own absorb only in the visible part of solar spectrum, into the infrared spectral range using infrared-active lead salt nanocrystal quantum dots (NQDs). Here we observed for the first time hole transfer from PbS NQDs to polymers as evidenced by the quenching of the PbS photoluminescence (PL), a sign of the presence of charge separating type II heterojunction. The type II band-offset at the NQD/polymer heterojunction enables efficient hole extraction from NQDs and leads to a record PCE of 3.80%, realized in a planar junction configuration under simulated air mass 1.5 global (AM 1.5G) irradiation of 100 mW/cm². The photocurrent has an extended spectral range spanning from the ultraviolet (UV) to the infrared (IR). Contributions from the polymer and PbS to the photocurrent were identified. Infrared photons (>700 nm) contribute about 30% of the photocurrent and yield a high external quantum efficiency (EQE) of 20% at 1050 nm.     

视频编码技术的专利状况分析

随着数字视频技术在通信、计算机以及广播电视等领域的广泛应用,涉及视频编码技术的专利申请量自2000年开始迅速增长。基于视频编码技术领域的专利文献,给出了对该领域专利总体变化情况的统计分析结果。针对视频编码技术的发展情况、重要申请人的专利特点以及专利发展趋势进行了详细的分析和深入的研究。     

前言

人们对后3G的要求是:在全球范围内实现无缝覆盖,进行包括语音、文本、图像、视频等在内的高速多媒体通信。为此,在有限频谱资源条件下,必须缩短无线信号的传输半径,极大限度地复用频谱资源,提高单位空间的信道容量。采用各种先进的无线传输技术的无线传输网络则在中、小范围内提供高速率、高质量的无线移动通信服务。因而WLAN和WPAN的需求和应用在不断增长,超宽带(UWB,ultra wide-band)等短距离、高空间容量的技术日益兴起,成为目前无线通信领域的热点。UWB的核心是冲激无线电技术,即利用持续时间非常短(纳秒、亚纳秒级)的脉冲波形来…     

干线传输线路一体化运维管理系统设计与实现

针对目前线路资源、维护任务和网络质量无法统一管理与集中监控的现状,在研究资源模型、任务流程和工作场景的基础上,提出了一种基于 GIS(地理信息系统)平台和 GPS(全球定位系统)智能终端的整体运维管理方案,并进行了管理流程、信息交互、数据验证、用户界面功能的设计与系统实现。实际应用结果表明,该系统显著提高了干线传输线路运维管理的效率。     

液晶光阀的双稳态特性研究

测量了TB3639型液晶光阀在电压驱动下的光谱特性及其光学双稳态特性,并讨论其产生光学双稳态特性的非线性效应物理机制,分析了液晶光阀的光学双稳态特性不明显的原因.分析结果表明,扭曲角对液晶光阀的光学双稳态特性影响较大,由于TN型液晶光阀的扭曲角只有90°,导致其双稳态特性不是很明显,TB3639型液晶光阀在某一电压范围内存在光学双稳态特性.     

基于FPGA的PCI接口控制器设计与实现

给出了一种基于FPGA实现PCI总线接口控制器的设计方案,从而解决了视频码流高速传输问题,使视频解码芯片能够实时解码.设计在Mode1Sim环境下对Verilog HDL源程序进行前仿真,在Xilinx ISE环境下进行逻辑综合、布局布线后下载到Xilinx公司生产的XC2V6000芯片内.在驱动和应用程序的配合下,FPGA实验板在33MHz时钟频率下,视频数据传输率达到42MB/s,数据传输效果很好,完全符合PCI总线的要求,为能够实时解码提供了高速码流.