间羧基偶氮羧光度法测定痕量铬的研究

研究了间羧基偶氮羧与Cr2 O2 -7的褪色反应 ,建立了一种新的测定痕量Cr(VI)的光度方法 .发现其在高氯酸介质中具有高灵敏的褪色反应 ,摩尔吸收系数达到 3 .5× 10 6L/mol·cmCr(VI)量在 0～ 48μg范围内符合比尔定律     

A study of propagation in Shenzhen city

Surveying the propagation path loss behavior of Shenzhen city and from the data recorded we can obtain the city’s path loss slopes, which can be comparatively regarded as the reliable bases of system design. Biography: ZHANG Yuan-qiao(1975-), male, Master candidate. Research direction: electronic magnetic theory.     

衰减信道下的决策融合问题

本文针对国际上近几年兴起的研究热点——无线传感器网络在信道衰减下的决策融合问题进行探讨。分析了已有传感器决策融合问题算法的结构,在已知信道传输错误概率的条件下,将信道无传输错误的分析方法推广到信道衰减的情况,对传输错误和融合律的关系进行了深入分析。对给定融合律的网络决策融合问题,获得了最优容错传感器观测量化器的必要条件并设计了迭代算法。在没有增加问题的计算复杂度的情况下,得到了最优观测量化器。与国际上现有结果不同,新结果不要求传感器决策条件独立,也不要求各传感器与融合中心之间的信道相互独立,具有更加广泛的使用范围。     

频率色散移动信道的仿真模型分析

通过分析频率色散移动信道的衰落特性，分别对该信道在快衰落特性，慢衰落特性以及同时考虑快衰落和慢衰落这三种情况下建立了数学模型和计算机仿真模型，并对计算机仿真结果进行了分析，提出了相应结论。     

多径衰落短波信道中SFH／MFSK通信系统的性能

分析研究了慢跳频／Ｍ进制频率键控（ＳＦＨ／ＭＦＳＫ）通信系统在存在瑞利（Ｒａｙｌｅｉｇｈ）衰落和莱斯（Ｒｉｃｉａｎ）衰落的多径延时短波信道上的性能，导出了其准确的比特差错率的表达式，表明多径干扰数及其强度对系统性能的影响．同时给出了它们的数值结果和性能曲线．     

Effect of multivalent cation substitution on the capacity fading of lithium manganese spinel cathodes

The introduction of Co, Al, and Ti into LiMn₂O₄ cathode powders has been studied in this work. The substitution of 25% Mn with either of these metals is expected to improve the cycle ability of the cathode, while the Jahn–Teller effect is suppressed. The solid-state reaction method is used in order to produce the cathode materials, which are prepared at 750 or 800 °C. The materials are characterized by X-ray data and, electrochemically, by galvanostatic cycling at the 4-V range. Their capacity fading behavior is evaluated, and a further investigation into cycling at a higher voltage range is also presented.     

岸船通信的抗干扰和保持通信时间预测研究

岸船通信面临着介质对高频电磁波( HF: High Frequency Electromagnetic Wave) 的吸收损耗、海面湍流对电磁波的散射、海面物体对电磁波的反射产生的多径信号干扰的问题。针对岸船通信通信传输信道的特点,建立其信道传输模型,求解出信道的单位冲激响应,提出了在岸船通信中接收机基于双调角器抗多径干扰的方法。该方法能有效地利用多径信号的能量,不需提高发射机功率即能提高通信质量,抗多径效果好且容易实现。建立高频电磁波电离层反射模型,使用解三角形算法研究了岸船通信能保持通信的时间,便于完善通信协议,提高通信质量。仿真结果表明,该方法白天最长能保持4． 5 h 通信,夜晚最长能保持7． 5 h 通信。     

Multiple re-configurable intelligent surfaces based physical layer eavesdropper detection for V2I communications

Inspired by the promising potential of re-configurable intelligent surface (RIS)-aided transmission in achieving the vision of 6th Generation (6G) network, we analyze the security model for a vehicular-to-infrastructure (V2I) network by considering multiple RISs (M-RIS) on buildings to act as passive relays at fixed distances from a source. In addition, multiple eavesdroppers are presented in the vicinity of the intended destination. Our aim is to enhance the secrecy capacity (SC) and to minimize secrecy outage probability (SOP) in presence of multiple eavesdroppers with the help of M-RIS in V2I communications. We propose a key-less physical layer security using beam-forming by exploiting M-RIS. The proposed approach assumes the concept of detecting eavesdroppers before the information can be transmitted via beam-forming by utilizing M-RIS. The results reveal that with consideration of M-RIS and beam-forming, the achievable SC and SOP performance is significantly improved while imposing minimum power consumption and fewer RIS reflectors.     

基于SCTP多归属主机特性的多路径传输算法研究

SCTP协议是新兴的传输层协议，具有许多值得开发的新特性，多归属主机特性就是其中之一。分析了多归属主机特性下数据的多路径同时传输的意义与存在的问题，并在此基础上提出了改进的协议算法，通过试验，改进后的算法解决了发送端不必要的快重传的问题，从而使得SCTP多归属主机特性下的多路径数据同时传输成为可能。     

GSM无线网络优化

先后对GSM无线网络的发展情况以及目前存在的问题进行了介绍,阐述了GSM无线网络优化的技术难点.介绍了BCCH载波与TCH载波的频率配置、信号衰落算法、干扰原理、动态功率控制的调节思路,以及提高网络质量,改善小区登陆与切换性能的措施.介绍了GSM900整体优化思路,以及实施效果.