CAD_4四圆单晶衍射仪的技术改造

对荷兰ENRAF NONIUS公司的CAD4四圆单晶衍射仪在缺乏核心技术资料的情况下进行了技术改造。剖析了仪器构造,控制机理,保留原有良好的四圆测角仪及高压发生器,彻底更换了主机控制和数据处理软件和硬件,使这台已运行十多年的故障频繁的旧仪器又恢复正常工作。软、硬件的升级改造使之达到了全新水平。     

基于非线性流形学习的人脸面部运动估计

由于人脸面部运动变化分布在一个低维非线性流形中,基于线性假设的主动外观模型采用主成分分析算法描述人脸形状的变化必然带来额外的估计误差.为降低或消除这一误差,该文提出一种改进的局部线性嵌入算法构建人脸形状-纹理空间,并将其应用于主动外观模型中.实验结果表明,不仅对于面部形变不大的人脸形状,局部线性嵌入-主动外观模型拥有更...     

The effect of IMU inaccuracies on airborne SAR imaging

When using motion compensation approaches based on the measurement of motion sensors, the residual uncompensated motion errors due to measurement instrument inaccuracies contribute to phase errors and hence degrade Synthetic Aperture Radar (SAR) images. This paper presents a model to compute the phase error caused by Inertial Measurement Unit (IMU) measurement inaccuracies. By analyzing SAR motion compensation method and the effect of lever arm, this model derives the contribution of each term of IMU inaccuracies towards the residual uncompensated motion errors and provides a method to calculate each order of the residual phase error. According to the model, computed results of the airborne X-band SAR system with POS AV510 accord closely with the actual image quality.     

Locally Welded Silver Nano‐Network Transparent Electrodes with High Operational Stability by a Simple Alcohol‐Based Chemical Approach

As an indispensable aspect of emerging flexible optoelectronics, flexible transparent electrodes, especially those comprised of metal nanowires, have attracted great attentions recently. Welding the nanowire junctions is an effective strategy for reducing the sheet resistance and improving the operational stability of flexible nanowire electrode in practical applications. Herein, a simple alcohol‐based solution approach is proposed to weld crossed silver nanowires by chemically growing silver “solder” at the junctions of the nanowires, forming transparent silver nano‐network electrodes with improved electrical conductivity and operational stability. Remarkably, silver nano‐networks can be rapidly formed by this simple approach under ambient condition and room temperature, requiring no assistance from heat, light, electrical current, or mechanical pressure. Furthermore, our results show that the nano‐network electrode formed from large diameter nanowires offers a better operational stability, whose trend is opposite to that of the untreated electrodes. To demonstrate the potential application of the highly stable silver nano‐network from large diameter nanowires, organic solar cells fabricated on the nano‐network electrode incorporated with silicon dioxide nanoparticles achieve comparable performance to the ITO control device. Consequently, strategy demonstrated in this work can contribute to low‐cost and highly stable transparent electrodes in emerging flexible optoelectronics.     

基于VB的主从机串行通信系统设计

串行通信是数据采集系统中最常用的通信手段之一。设计并研制了基于VB的LED大屏幕显示串行数据通信系统,具有编程灵活、控制通信对象容易的优点。通过8250的奇偶校验位与单片机的SM2位的配合,实现了PC机与多个单片机的串行数据通信。介绍了基于VB6.0进行串行通信的流程和编程,较好地解决了同时使用通信方式0与方式1时引起的RXD端口的冲突问题。实验证明,该设计简单、实用,提高了系统设计的效率。     

On the Numerical Stability of the Precise Integration Time-Domain (PITD) Method

In this letter, the stability issue of the recently proposed 3-D precise integration time-domain (PITD) method is reinvestigated. It is found that the PITD is not unconditionally stable; its stability condition is strongly dependent on the preselected number of sub time-steps and sizes of numerical cells as well as the order of the approximation used. However, since the upper limit of time step is found to be proportional to the number of sub time-steps, the time step can be of a value much larger than the Courant-Friedrich-Levy limit of the conventional finite difference time domain. Numerical examples are presented to verify our analysis.