Pilot power minimization with coverage and locatability constraints in CDMA systems

Position location (PL) of a UE requesting E-911 services should be provided by wireless communication service providers, according to the Federal Communications Commission (FCC) regulations. Raising pilot power fraction can improve the system locatability, while it may also cause pilot pollution and increase interference to UEs in neighboring cells. In this letter we find the optimal pilot power allocation subject to coverage and locatability constraints. The results have shown that with new localization techniques such as idle period downlink (IPDL) and cumulative virtual blanking (CVB), the coverage and locatability constraints can be satisfied without requiring long integration time and large pilot power fraction.     

光电探测器的激光破坏（损伤）阈值分析

本文系统收集各种光电探测器及其相似材料在受到激光辐照时所导致的软、硬破坏效应（有时称为激光损伤）,综合对比分析各种破坏阈值的大小,为激光与光电探测器相互作用的研究提供一个较为全面系统的参考。     

LP-MOCVD生长InGaAlP外延层In组分控制的动力学分析

本文分析了低压转盘ＭＯＣＶＤ生长室中气流的流动特征,首次提出了在高温（７００℃左右）下生长ＩｎＧａＡｌＰ外延层时,抑制Ｉｎ组分脱吸附的“动压力模型”．解释了托盘转速和生长压力等生长参数对Ｉｎ组分控制的影响．     

软件无线电中直接波形合成的研究

直接数字频率合成（DDS）是一种新型的频率合成技术。介绍了如何利用DDS技术来产生调频波形及其他的数字调制波形;阐述了一种新的适合于软件无线电实现的算法,即采用预先计算后存贮在贮存器中的波形来代替实时运算,直接合成数字调制波形（DWS）;研究了一种压缩查找表的方法。此外,还对此算法在实现过程中遇到的截断误差、运算量和存贮量的问题进行了探讨。对于所提及的算法,给出了仿真结果。     

Super-Stretchable,Anti-Freezing,Anti-Drying Organogel Ionic Conductor for Multi-Mode Flexible Electronics

Due to their intrinsic flexibility, tunable conductivity, multiple stimulus-response, and self-healing ability, ionic conductive hydrogels have drawn significant attention in flexible/wearable electronics. However, challenges remain because traditional hydrogels inevitably faced the problems of losing flexibility and conductivity because of the inner water loss when exposed to the ambient environment. Besides, the water inside the hydrogel will freeze at the water icing temperatures, making the device hard and fragile. As a promising alternative, organogels have attracted wide attention because they can, to some extent, overcome the above drawbacks. Herein, a kind of organogel ionic conductor (MOIC) by a self-polymerization reaction is involved, which is super stretchable, anti-drying, and anti-freezing. Meanwhile, it can still maintain high mechanical stability after alternately loading/unloading at the strain of 600% for 600 s (1800 cycles). Using this MOIC, high-performance triboelectric nanogenerator (TENG) is constructed (MOIC-TENG) to harvest small mechanical energy even the MOIC electrode underwent an extremely low temperature. In addition, multifunctional flexible/wearable sensors (strain sensor, piezoresistive sensor, and tactile sensor) are realized to monitor human motions in real time, and recognize different materials by triboelectric effect. This study demonstrates a promising candidate material for flexible/wearable electronics such as electronic skin, flexible sensors, and human-machine interfaces.     

Correlating mobility with social encounters: distributed localization in sparse mobile networks

Wireless Networks - Most existing connectivity-based localization algorithms require high node density which is unavailable in many large-scale sparse mobile networks. By analyzing large datasets...     

信息化建设过程风险分析及其智能化管理方法

针对信息化项目低成功率的现状,分析信息化建设过程中存在的技术选择、体制改造、建设效益和系统整合等各种建设风险,探讨智能化管理方法在信息化建设过程风险防范中的应用途径,通过使用智能化策略生成、智能化风险评估和智能辅助决策与修正等方法,增强识别、分析和处理信息化建设过程系统中风险因素的能力。该研究可为促进我国信息化建设的发展提供参考。     

预警机飞行器管理系统的功能结构研究

介绍飞行器管理系统的发展背景,阐释机载系统综合发展的必然趋势。未来预警机作为探测、指挥、引导、控制、通信的综合载体,根据其任务特点,讨论预警机飞行器管理系统应该具备的基本功能,运用综合系统控制结构原理将整个系统的功能结构划分为感知层、辅助决策层、执行层3部分。该研究可为设计预警机的飞行器管理系统提供参考。     

引入GaN过渡层对Si（111）衬底上生长GaN外延的影响

本文研究了在Si(111)衬底上生长GaN外延层的方法。相比于直接在AlN缓冲层上生长GaN外延层,引入GaN过渡层显著地提高了外延层的晶体质量并降低了外延层的裂纹密度。使用X射线双晶衍射仪、光学显微镜以及在位监测曲线分析了GaN过渡层对外延层的晶体质量以及裂纹密度的影响。实验发现,直接在AlN缓冲层上生长外延层,晶体质量较差, X射线(0002)面半高宽最优值为0.686°,引入GaN过渡层后,通过调整生长条件,控制岛的长大与合并的过程,从而控制三维生长到二维生长过渡的过程,外延层的晶体质量明显提高, (0002)面半高宽降低为0.206°,并且裂纹明显减少。研究结果证明,通过生长合适厚度的GaN过渡层,可以得到高质量、无裂纹的GaN外延层。