CSTN-LCD用铬版清洗效果的改善

利用铬版清洗机对CSTN-LCD用铬版进行清洗处理,分析了清洗过程中出现的铬层脱落现象,铬层脱落与轴向喷射压力和水平切力密切相关,通过调整转速和喷射压力探索了安全使用条件:在转速不超过1000r/min,喷射压力低于0.5×105Pa的情况下使用铬版清洗机进行清洗是相对安全的。同时采用预清洗处理的方法满足清洁要求,使换线时间由平均3h缩短到平均1h以内,年产能提高270000片。     

宽带直升机卫星通信的重发策略研究

针对宽带直升机卫星通信信道的周期性衰落特性建立了周期性删除信道模型,基于此模型研究了重发分集的策略,推导了给定信道删除周期、窗口宽度、突发长度下重发次数、重发间隔的选择方法,讨论了重发模式与参数鲁棒性、系统设计需求的关系,并结合实例讨论了系统设计的设计步骤以及其他考虑因素。分析表明,采用两次重发可在大多数直升机信道条件下实现可靠传输,且具有较好的灵活性、较低的实现复杂度。     

一种快速的DS/FH混合扩频信号捕获方案及其性能分析

为了提高DS/FH混合扩频信号的捕获速度,提出了一种将DS/FH信号中三维搜索转化为二维搜索的快速捕获方案。通过对搜索过程的详细分析,推导出在单、双驻留条件下的平均捕获时间数学表达式以及高斯信道下系统的检测性能计算公式。理论推导与仿真结果表明:相对于传统的捕获方式,该方案有效地缩短了系统的平均捕获时间,具有更强的抗噪性能,适用于存在较强噪声的复杂通信环境。     

对地面弱小目标的检测算法的研究

在研究地面弱小目标时,由于环境、人为误差及成像系统本身的影响,摄像机拍摄的视频会出现画面抖动比较厉害、成像质量差的现象。因此,需要对图像序列进行运动补偿。为实现对地面弱小目标的检测,提出了一种基于Harris角点检测的对地面弱小目标的检测算法。该算法利用了残差图中的灰度信息及残差图序列,在时间上具有连续性,算法的稳定性高,精度较高,实时性好。能够很好地剔除残差图中的虚警点,在较高精度下大大提高了对于地面弱小目标检测的水平。     

Chip‐interleaving direct sequence spread spectrum system over Rician multipath fading channels

Chip interleaving (CI) is a unique technique to exploit time diversity in direct sequence spread spectrum (DS/SS)‐based systems operating in fading environments. In order to facilitate design of CI systems in various fading situations, we present a performance analysis for CI DS/SS system over Rician multipath time‐varying fading channels. We derive the analytical bit error rate (BER) expression for CI DS/SS to allow fast and accurate evaluation of BER performance based on the interleaving depth selected, spreading codes employed, and the time correlation function of the channel. We then discuss some ideal cases by using the analytical results to reveal some of the insights presented in the performance analysis. For the purpose of comparison, we also obtain the BER expression for conventional DS/SS system as a special case of CI system with an interleaving depth of one. Using numerical examples, we verify the analytical results with computer simulations and illustrate the BER performance behavior of CI DS/SS system with varying interleaving depth for all possible combinations of two sets of spreading codes of different type and two different time correlation functions of the channel. Copyright © 2011 John Wiley & Sons, Ltd.     

基于时间差和角度的数据融合定位算法研究

定位系统中大部分现在存在的算法通常没有考虑综合利用空域、时域信息,而只选择了少量的测量信息.为了克服这个缺陷,提出了一种新的TDOA/AOA数据融合定位算法,这种算法充分利用了来自多个传感器的冗长信息,其中包括到达时间、到达方向.仿真实验结果表明与传统的算法相比,这种算法具有更好的定位精度和收敛速度,进一步改进了系统的可靠性,是一种有效、可行的定位算法.     

A source authentication scheme based on message recovery digital signature for multicast

The source authentication is an important issue for the multicast applications because it can let the receiver know whether the multicast message is sent from a legal source or not. However, the previously related schemes did not provide the confidentiality for data packets. In addition, the communication costs of these schemes are still high for real‐time applications in the multicast environments. To solve the aforementioned problems, we propose a new source authentication scheme based on message recovery signature for multicast in this paper. In the proposed scheme, the encrypted data can be embedded in the digital signature, so the communication loads can be greatly reduced. In addition, the digital signature contains the encrypted data, and thus the confidentiality of data packets can be well protected. According to the aforementioned advantages, the proposed scheme is securer and more efficient than the related works for the real‐time applications. Copyright © 2013 John Wiley & Sons, Ltd.     

适用于纹波控制型DC-DC控制器的比较器设计

设计一种适用于纹波控制（Output-Ripple-Based Control）的Buck型DC-DC控制器的比较器,根据PSIM搭建的仿真模型,分析主环比较器性能对系统的影响,设计具有三级预放大的高增益,低延时,低失调电压的比较器电路,采用两种温度系数的电流补偿比较器增益,稳定增益,采用0.5umBiCOMS工艺进行仿真验证,下降沿延时27ns,增益123dB,随温度最大增益变化3.2%,失调电压90uV,达到系统要求。     

Design,fabrication and characterization of miniature RF MEMS switched capacitor based phase shifter

This paper aims to present in detail the design, fabrication and the various characterization techniques adopted in realizing a novel miniature-size switched capacitor based phase shifter. The work strives to provide an all-round development of a DMTL (Distributed MEMS Transmission Line) based phase shifting unit yielding an overall phase shift of 15° at a frequency of 15 GHz. The RF MEMS (Radio Frequency Micro Electro Mechanical Systems) Switched Capacitor based phase shifter has highly miniaturized dimensions, and is capable of solving many limitations to which the conventional Switched Capacitors are mostly susceptible. This miniature RF MEMS switched capacitor actuates at a low actuation voltage of 12 V, exhibits a fundamental frequency of vibration as high as 1.468 MHz and a switching time of 1.4 µs which is an improvement over the other reported designs. Various characterization results seem to validate the simulations.     

局域寿命控制NPT-IGBT瞬态模型

提出了局域寿命控制下NPT-IGBT的瞬态模型,并与数值分析结果进行了对比,验证了模型的正确性.该模型采用了准静态近似,将关断过程分为快速下降阶段和缓慢下降阶段分别加以求解而得到.基于该模型,详细讨论了局域低寿命区参数对关断时间的影响.该模型将有助于理解局域寿命控制NPT-IGBT的关断过程物理图像,同时也可以用于指导该类器件的设计和优化.文中所采用的分析方法具有一定的普适性,其他类似结构和器件亦可采用此方法进行分析.