电脉冲下TiC颗粒增强Ni-Cr合金中位错组态的变化

TiC颗粒增强Ni80Cr20合金经电脉冲处理后,位错组态发生规整化,平直化排列,位错堆积形成位错墙。这表明电脉冲处理具有类似于退火的回复作用,此外,电脉冲处理还可以起到强化TiC颗粒增强相与基体之间结合的作用。     

重度污染天气下大气颗粒物PM_(1.0)物理化学特征的透射电子显微镜研究

大气颗粒物样品采自徐州市区2013年12月~2014年1月间重度污染天气。采样期间PM1.0主要由烟尘颗粒、复合酸冷凝颗粒、硫酸盐颗粒、矿物颗粒、金属及金属氧化物颗粒等组成。本文通过透射电子显微镜(TEM)及能谱仪(EDS)给出的大气颗粒物PM1.0高分辨结构信息、颗粒相尺寸及化学相尺寸信息、颗粒相中不同化学相嵌布特征信息等,对组成颗粒相的化学相连生关系进行了比较系统的分析研究。分析数据表明,大气颗粒物PM1.0的颗粒模态转变过程与颗粒物形成过程的相关性较强。异相凝结颗粒中化学相物质结构类型的判别是识别颗粒成因及形成过程的重要因素。     

晶片CMP后表面纳米颗粒的去除研究

对晶片化学机械抛光(CMP)后表面吸附的纳米颗粒去除进行了研究,分析了晶片表面吸附物的种类及吸附机理。由于晶片表面吸附的有机物多为大分子物质,它在晶片表面的吸附除了容易处理的物理吸附外,还会和晶片表面构成化学键,形成难以处理的化学吸附。对清洗过程中颗粒的去除有严重的影响,提出利用电化学清洗,结合表面活性剂和兆声波清洗的方法去除晶片表面的纳米颗粒。经金相显微镜观察和原子力显微镜检测,晶片表面纳米颗粒能得到很好地去除,效果明显优于单纯的兆声波清洗方法。     

基于ADSP-21261的数字效果器的设计

介绍了采用AD公司的SHARC ADSP-21261组成的数字音频信号处理系统及系统的软硬件设计，并对音频信号的混响处理算法进行了论述。经实际应用证明，该系统是一个不错的音频信号采集与处理系统。     

复合鱼鳞型超构材料中光控Fano谐振的设计

为解决传统超构材料存在的结构一旦形成,其谐振特性便无法进行动态可调的问题,本文将鱼鳞型超构材料与光电导材料硅相结合,实现了太赫兹波段Fano电磁响应的动态调控。该复合超构材料由鱼鳞型金属线、硅层以及聚酰亚胺组成。在鱼鳞型结构的金属弧线无、有缝隙两种情况下,研究了电磁波的入射角度和硅的电导率对Fano谐振的影响。当硅的电导率达到1×10³ S/m时,多频点电磁响应的调制深度都接近1。结果表明,调节缝隙宽度可以成为Fano谐振工作频率调控的有效方式。本文为实现超构材料中Fano谐振的可调谐特性提供了一种可行途径,对实际应用中太赫兹波的主动调控、传感等方面具有重要意义。     

纳米VO2薄膜相变特性的红外透射表征研究

采用双离子束溅射VOx薄膜附加热处理的方式制备纳米VO2薄膜,利用X射线衍射仪和扫描电子显微镜分别对其结晶结构和表面形貌进行了测试,利用傅立叶变换红外光谱仪(FTIR)对热驱动下纳米VO2薄膜相变过程中的光学性能进行测试与分析。实验结果表明,经400℃N2热处理后,获得了由纳米颗粒组成的VO2薄膜;在所测试的红外波段,纳米VO2薄膜内颗粒发生相变的初始温度随波长的增加而升高,薄膜的相变温度点随波长增加也逐渐升高。     

LambdaDNA诱导非细胞体系核重构过程的超微结构研究

非洲爪蟾未受精的卵细胞去胶膜后,经钙离子载体A23187活化及松胞素B处理,10,000G离心裂胞,除掉脂滴、卵黄颗粒、色素颗粒及卵核等,可得到可溶性胞质。在可溶性胞质中先加入ATP再生系统。将在65℃处理5分钟的Lambda DNA引入上述爪蟾卵非细胞体系,置22℃温育。以温育开始为零时,每隔一定时间取样固定做电镜观察,共取到温育4小时。取出的样品用戊二醛、锇酸双固定,Epon812包埋后做超薄切片,经醋酸双氧铀——柠檬酸铅染色,在JEM-100CX透射电镜下观察。同时按常规方法做冰冻蚀刻观察。     

SEM研究表面强化铬镍钢的磨损机制

本文用扫描电子显微镜及其附带的X射线能谱装置,研究了经表面强化和表面强润化复合处理的同种钢试样间的干滑动磨擦磨损所形成的表面形貌及磨损颗粒。研究表明:不同特征的表面磨损形貌和各种有代表性的磨损颗粒与不同类型的磨损作用机制和磨损进程密切相关。而用扫描电子显微镜进行这种研究对于揭示材料磨损过程的微观本质是非常有效的。     

海洋气溶胶组分的EDS分析及其形成机理的研究

研究海洋气溶胶的化学组成,形成机理、及人为排放污染物经长距离输送进入海洋大气产生什么变化,已日益引起人们的重视。通过对来自西太平洋海域上空的气溶胶颗粒的SEM观察和EDS分析,首次证明了在远离陆地的海域上,气溶胶的组分主要是由海水鼓泡运动产生的大量海盐气溶胶(主要成分为NaCl)粒子,在大气中与陆地经长距离输送来的气溶胶细颗粒碰撞而吸附其表面。本文讨论了气溶胶x射线面分布图时某些参数的选择。以及利用气溶胶颗粒处于由不被EDS检测的超轻元素组成的滤膜上的特点,通过阀值设置消除x射线面分布图上的背底。     

纳米硅表面与界面的扫描隧道显微镜研究

本文应用扫描隧道显微镜（ＳＴＭ），对使用等离子体增强化学气相沉积法（ＰＥＣＶＤ）制备的纳米硅（ｎｃ－Ｓｉ：Ｈ）薄膜进行了研究，得到颗粒上以及颗粒间界的原子结构图像，从图像上可以得出：（１）纳米硅薄膜是由许多不同大小的颗粒所组成。这些颗粒同时又是更小的微颗粒所组成。（２）微颗粒的表面及界面原子排列可以分为四种形式；环状结构，线状结构，网装结构以及无规的随机排列。（３）观察到环状结构不仅存在于界面，而     

Some characteristics of commonly used time scales

Various examples of ideally defined time scales are given. Realizations of these scales occur with the construction and maintanance of various clocks, and in the broadcast dissemination of the scale information. Atomic and universal time scales disseminated via standard frequency and time-signal broadcasts are compared. There is a discussion of some studies of the associated problems suggested by the International Radio Consultative Committee (CCIR).     

Multiple time scales for nonlinear systems

In this paper we extend the results on the multiple time-scale structure for linear autonomous systems of the form $$\dot x = A( \in )x$$ (cf. Coderchet al. [1]) to nonlinear autonomous systems. Our main result is in obtaining conditions under which the linearized system and the nonlinear system around an equilibrium point have the same time-scale structure.     

Stability of nonlinear systems with three time scales

We study the asymptotic stability of a singularly perturbed nonlinear time-invariant systemS _v , which has three vastly different time scales. The systemS _v is approximated by three simpler systems over different time intervals. We give a straightforward proof of the fact that the asymptotic stability ofS _v is guaranteed when the equilibrium points of the three simpler systems are exponentially stable and when the parameters and are sufficiently small.Research sponsored by the Joint Services Electronics Program, Contract Number F4962084-C-0057, and NASA, Grant NAG2-243.     

新型可重构结构能适应未来芯片集成度的提高

当前集成电路制造技术远远超过设计技术水平。现在单个芯片上能够提供的逻辑线路的门数,数量是如此众多,如何有效地充分利用这些门数,已经成为困扰计算机科研人员的一个难题了。何况新的制造技术还在继续层出不穷,原子规模级的开关线路虽然尚未成为现实,但是已经显示能够进一步提高芯片集成度的可能性。一旦成为现实,将进一步使这一个困扰设计人员的难题变得更加严重。近来出现了一种称为Cell Matrix（单元阵列）的新结构。看来这种新结构有可能解决这个困扰设计人员的难题。     

Evaluating evapotranspiration at local and regional scales

Combining remotely sensed data with ground-based meteorological data allows the evaluation of evapotranspiration (the evaporation of water from soil and plant surfaces) at local and regional scales. Remote sensors can provide information on reflected solar radiation and surface temperatures. The remaining variables in the energy balance equations must be measured at ground level, estimated, modeled, or ignored. It is how these variables are evaluated that distinguish the several approaches to estimating evapotranspiration. In general, regional scale methods would apply to part or all of a satellite image, and use meteorological data from local weather stations. Local scale techniques would rely largely on airborne remote sensors and on-site measurements of the pertinent meteorological factors at the time of remote-data collection. In this paper, methods for estimating evapotranspiration on both local and regional scales are reviewed, and some factors that complicate its measurement are discussed.     

基于仪表放大器电子秤的设计

为了解决因微弱信号放大而影响电子秤精度的问题,采用了仪表放大器作为压力传感器前置放大器,解决了由放大环节带来的失调电压和温漂等问题。简要论述了电阻应变式称重传感器的工作原理、设计了系统硬件电路与软件。经测试设计的电子秤误差小于0.3%,且具有数据准确稳定、称量快捷等特点。     

Fast implementation of the continuous wavelet transform withinteger scales

We describe a fast noniterative algorithm for the evaluation of continuous spline wavelet transforms at any integer scale m. In this approach, the input signal and the analyzing wavelet are both represented by polynomial splines. The algorithm uses a combination of moving sum and zero-padded filters, and its complexity per scale is O(N), where N is the signal length. The computation is exact, and the implementation is noniterative across scales. We also present examples of spline wavelets exhibiting properties that are desirable for either singularity detection (first and second derivative operators) or Gabor-like time-frequency signal analysis     

音式阶的合理性模识别校对方法

音阶识别方法不能结合乐音的物理和音乐特性,造成乐音处理信号量杂乱无序。针对该问题,通过复音音高确定转录音符集合,引入频谱图、谱平滑性和调和性估计建立HMM模型。分析对比实验结果表明,HMM模型可以完成乐音物理与音乐特性结合,改善乐音处理信号量杂乱无序现象。     

Tipping the scales in your favor when uprating

Many parts with leading-edge technologies (e.g., microprocessors, low-voltage logic devices, and high-capacity DRAMs) are available mostly in commercial or industrial temperature ranges. Some companies are responding by using the available parts in temperature ranges wider than those for which they are specified (uprating). The use of uprated parts should be considered as an option to mitigate environmental mismatch only when no other feasible alternative can be found. Companies who uprate parts must follow documented, controlled and repeatable processes, and they still may be subject to liability if a product that used uprated parts fails or is suspected to have caused harm. Product liability defenses are available to companies who use electronic parts outside the original manufacturer's specified temperature ranges. In order to maximize the effectiveness of these defenses, however, a company must be vigilant in seeking out ways in which it can demonstrate the viability of these defenses before the lawsuit is ever filed. Both the government contractor defense and the contract specification defense are vehicles around which a company can establish a product liability prevention program. In the final analysis, there is no substitute in product liability prevention for the training and education of employees and the endorsement by senior management of such a program     

Alternative time scales for systems with random usage

In various reliability applications, there can be different time scales in which to measure time to failure, or assess the performance of objects. For instance, for automobiles the chronological age & the total number of driving hours, as measures of usage, are good candidates for the time scale. An impact of a random usage on some properties of time to failure distribution functions is studied. It is shown that a random usage can change the shape of the failure rate of an object compared with the shape of the failure rate for the deterministic usage. Specifically, the sharply increasing failure rate can turn into a decreasing one, which is, in fact, surprising. The random usage can also change the aging properties of distributions under consideration, and this should be taken into account in applications. Several simple examples illustrate the developed concept.