用标度理论和蒙特卡洛方法研究微晶硅薄膜的生长机制

使用热丝化学气相沉积技术制备微晶硅薄膜(沉积速度为1.2nm/s),通过原子力显微镜研究了薄膜前期生长的粗糙化过程.按照标度理论获得微晶硅薄膜的生长因子为β≈O.67,粗糙度因子为α≈O.80,动力学因子为1/z=0.40.这些标度指数不能用一般的生长模型来解释.通过蒙特卡罗模拟给出与实验一致的结果.模拟表明,入射流方向、生长基元的类型和浓度、生长基元的粘滞、再发射和影蔽过程都对微晶硅薄膜的表面形貌有比较重要的影响.     

Digesting Commercial Clips from TV Streams

A commercial system that performs syntactic and semantic analysis during a TV advertising break could facilitate innovative new applications, such as an intelligent set-top box that enhances the ability of viewers to monitor and manage commercials from TV streams.     

Excel求解常微分方程组的两种方法

在实际应用中,常需要建立多个物理量随某一物理量(如:时间、温度等)变化的常微分方程组及对其求解,Excel广泛应用于经济、金融、工程、科研、教学等领域,用Excel求解常微分方程组具有一定的实际意义。笔者叙述2种Excel求解常微分方程组方法:用VBA编程求解、调用Matlab求解,并在实际编程环境中调试运行。     

Scaling and technological limitations of 1/f noise and oscillator phase noise in SiGe HBTs

This paper examines the impact of SiGe HBT scaling on 1/f noise and phase noise of oscillators and frequency synthesizers. The increase of transistor speed with scaling is shown to significantly increase the sensitivity of oscillation frequency to 1/f noise and, thus, degrade close-in phase noise, but decrease the sensitivity of oscillation frequency to base current shot noise and base resistance thermal noises. The results show that corner offset frequency defined by the intersect of the 1/f³ and 1/f² phase noise has little to do with the traditional 1/f corner frequency. The relative importance of individual noise sources in determining phase noise is examined as a function of technology scaling, device sizing, and oscillation frequency. The collector current shot noise and base resistance noise are shown to set the fundamental limits of phase noise reduction. A methodology to identify the maximum tolerable 1/f K factor is established and demonstrated for the HBTs used     

Improved voltage clamping scheme for ZVS PWM three-level converter

This paper proposes an improved zero-voltage-switching pulsewidth-modulation (ZVS PWM) three-level converter, which is improved from the original ZVS PWM three-level converter by merely exchanging the position of the resonant inductance and the transformer, such that the transformer is connected with the lagging switches. The improved converter has several advantages over the original, e.g., the clamping diodes conduct only once in a switching period, and the resonant inductance current is smaller in zero state, leading to a higher efficiency and reduced duty-cycle loss. A blocking capacitor is usually introduced to the primary side to prevent the transformer from saturating. This paper analyzes the effects of the blocking capacitor in different positions, and a best scheme is determined. A 2.5-kW prototype converter verifies the effectiveness of the improved converter and the best scheme for the blocking capacitor.     

航空多角度偏振成像仪及其光学系统设计

航空多角度偏振成像仪采用面阵CCD探测器进行画幅式成像,分时获取三个偏振方向图像的工作方式,并最终解析出偏振信息.光学系统设计充分考虑了该系统的特点,设计出了全视场80°的像方远心超低畸变的镜头,满足了航空多角度偏振成像仪的系统要求.     

High Temperature Superconducting Magnetic Energy Storage and Its Power Control Technology

High temperature superconducting （HTS） power inductor and its control technology have been studied and analyzed in the paper. Based on the results of simulations and practical experiments, a controlled release scheme has been proposed and verified for developing a practical HTS SMES prototype.     

三维两粒子赤道纠缠态的概率远程制备

提出了一个概率远程制备三维两粒子赤道纠缠态的方案.在该方案中,用两个非最大三维两粒子纠缠态作为量子信道,通过三维两粒子的投影测量、引入辅助的三维单粒子并运用相应的幺正变换可实现量子态的几率远程制备.     

简易LED点阵汉字显示控制模块设计

LED控制模块在程序上完成了内码到区位码、区位码到字模的转换,给出了关键代码。硬件设计上由12块8×8LED点阵模块组成显示屏,控制器采用AT89S52微处理器,由P0口和P2口控制显示屏的行、3块4-16译码器74LS154控制显示屏的列,将字模扫描到LED显示屏,从而显示汉字。     

Channel estimation and interference suppression for uplink CDMA mobile communication systems

Wireless communications for mobile telephone and data transmission is currently undergoing very rapid development. Code division multiple‐access (CDMA) implemented with direct sequence spread spectrum signaling is among the most promising multiplexing technologies for cellular telecommunications services. In this paper, jointly period inserted pilot symbols assisted recursive (PIPSAR) channel estimation and interference suppression techniques are proposed for uplink CDMA mobile communication systems. The uplink CDMA mobile communication system model is described in the form of space‐time domain through antenna array and multipath expression. Interference suppression is achieved by using adaptive minimum mean squared error (MMSE) digital filters that span several successive received chip oversampling vectors of a symbol interval. PIPSAR techniques are used to estimate channel parameters. The correlation between the successive periods is considered to further improve the performance of the proposed scheme. Analysis and simulations are used to evaluate the performance of the proposed scheme. Copyright © 2004 John Wiley & Sons, Ltd.