一种相干分布目标的DOA-时延联合估计算法

在城市密集环境情况下,基于传统点目标模型的多径空时参数(波达方向与相对时延)联合估计算法往往出现性能恶化。本文通过重新构造空间流形与时间流形,给出了一种更符合密集环境的空时相干分布信号模型,并在获得空时联合信号子空间后,分别抽取空间、时间子矩阵构造空间谱与时间谱,通过搜索谱峰得到所需空、时多径参数,最后利用空时流形向量与空时联合噪声子空间的正交性质实现空时参数配对。与TST-MUSIC等算法相比,该算法仅需要两次搜索及一次配对过程。仿真实验表明,该方法能够有效估计相干分布信号空时参数,抑制分布扩展影响,实现多个参数的自动配对。     

网络融合与业务创新

从分析用户需求的根本性变化,提出应对一些挑战和变化的措施。通过提供网络融合和业务创新的五大核心要素,介绍阿尔卡特朗讯的网络融合和业务的创新解决方案。     

Design and Fabrication of Asymmetric MOSFETs Using a Novel Self-Aligned Structure

A novel asymmetric MOSFET with no lightly doped drain on the source side is simulated on bulk Si using a device simulator (SILVACO). To overcome the problems of the conventional asymmetric process, a novel asymmetric MOSFET using a mesa structure and a sidewall spacer gate is proposed, and it provides a self-alignment process, aggressive scaling, and better uniformity. First of all, we have compared the simulated characteristics of the asymmetric and symmetric MOSFETs. Basically, both asymmetric and symmetric MOSFETs have an n-type channel and the same physical parameters. Compared with the symmetric MOSFET, the asymmetric MOSFET shows better device performance. Moreover, we have successfully fabricated 50-nm asymmetric NMOSFETs based on simulation results and investigated its operation and characteristics.     

Simple adaptive matching antenna

The performance of handheld wireless devices can be affected when they are held close to parts of the human body. Deterioration can vary from person to person or even different forms or types of use. One of the problems is antenna impedance mismatch in different situations. Reported is an adaptive matching antenna realised by combining a simple monopole antenna and an oscillator with a phase-locked loop (PLL). The PLL helps to monitor return loss and to adjust the matching network automatically. It is found that the antenna can operate in the whole 2.4 GHz ISM band no matter how close it is to the human body after the adaptive matching circuit is applied.     

Properties of Indium-Doped ZnO Films Prepared in an Oxygen-Rich Plasma

Indium-doped zinc oxide (ZnO:In) films were prepared in an Ar:O₂ plasma by reactive magnetron sputtering. The x-ray diffraction (XRD) patterns presented the crystal structures of ZnO:In films, while transmission spectra and photoluminescence (PL) spectra showed the changed band gap and the visible emission from defects, as compared to the PL spectra of undoped ZnO films. It was concluded that the increase of substrate temperature enhanced the crystal quality of ZnO:In films; the incorporation of In made the c-axis constant of the samples larger than that of undoped ZnO films; the blue emission was due to the transition from an unknown donor level by indium doping to the valance band; and the orange-green emission originated from acceptor defects (O_Zn) formed in the O-rich plasma. Meanwhile, the current- voltage characteristics and persistent photoconductivity phenomenon also could be explained by the increased acceptor defects (O_Zn) that formed when the substrate temperature was increased.     

X射线安检系统的图像非均匀性校正方法

首先分析了X射线安检系统应用中图像非均匀性的原因,并在此基础上提出了一种新的软硬件结合的校正方法。此方法根据线性校正算法给每个探测单元以相应的校正参数,然后通过增益控制电路和零点补偿电路来调整最终的输出。实验结果表明,经过软硬件校正后图像水平条纹基本消失,图像效果明显改善。     

通道在层次化验证平台中的应用

本文首先引入了通道的概念;接着介绍了层次化验证平台的结构,并说明了RVM验证方法学中Channel类的函数及其用法.最后,我们在USB测试平台上给出了一个用通道连接处理器和驱动器的实铡.     

Reliability-centered predictive maintenance scheduling for a continuously monitored system subject to degradation

This paper tries to integrate sequential imperfect maintenance policy into condition-based predictive maintenance (CBPM). A reliability-centered predictive maintenance policy is proposed for a continuously monitored system subject to degradation due to the imperfect maintenance. It is assumed that the system hazard rate is a known function of the system condition and then can be derived directly through CBPM. A hybrid hazard rate recursion rule based on the concept of age reduction factor and hazard rate increase factor is built up to predict the evolution of the system reliability in different maintenance cycles. Whenever the system reliability reaches the threshold R, an imperfect preventive maintenance (PM) is performed on the system. The optimal reliability threshold R is determined by minimizing the cumulative maintenance cost per unit time in the residual life of the system which is based on simulation. Finally, a discussion is presented to show how the optimal results depend on the different cost parameters.     

大容量NOR Flash与8位单片机的接口设计

在8位单片机系统中使用NOR Flash存储器,可以实现用简单设计完成复杂任务的目标,从而有效地缩短产品的开发周期,降低产品的制造成本.本文以NOR Flash存储器SST39SF040和MCS-51系列单片机为例,详细介绍大容量NOR Flash存储器与8位单片机的接口技术,给出硬件连接电路和扇区擦除操作的源程序代码.     

运载火箭减载缓释机构缓释特性分析

为了提高发射可靠性,未来的运载火箭拟采用牵制释放系统.以一种新型强制式牵制释放系统为例,应用结构分析软件MSC/Marc建立了分析该系统中减载缓释机构缓释特性的有限元模型.计算结果表明:缓释销选用应变率无关型材料时,该机构的缓释力-行程曲线受火箭起飞速度等因素的影响较小,运载火箭的缓释行程以及缓释力-行程曲线可由减载缓释机构的设计来准确的控制.该机构对机械加工精度的要求不苛刻,易于加工.在选择缓释销的材料时应注意缓释过程中销内部可能出现的中心破裂.