SNR-based weighted cooperative spectrum sensing in cognitive radio networks

Cooperative spectrum sensing (CSS) is an approach to confront fading environment. However, in conventional cooperative spectrum sensing (CCSS), the difference among the secondary users (SUS) is ignored when SUS suffer from different fading. In this article, a signal-to-noise ratio (SNR)-based weighted spectrum sensing scheme is proposed to improve the sensing performance. The sensing performance of the weighted spectrum sensing scheme is then derived. Considering the minor contribution of the SUS with small weighted factor, a selective CSS scheme is proposed, where SUS with low SNR are not selected into cooperative spectrum sensing. The simulation results confirm the analytical results. And the performance of weighted scheme is better than that of conventional schemes. In the case where the SNR of SUS are randomly distributed, the performance of selective scheme is almost the same as the weighted scheme while the number of cooperative SUS is reduced to save the consumption of system resource in cooperation with little additional complexity.     

超视距空战下的态势评估技术研究

态势评估技术是智能战术辅助决策系统的关键技术之一,针对现代超视距空战的特点,提出了一种新的超视距空战下的态势评估算法。通过研究典型的空战态势情形,总结得出超视距空战下对态势起决定性作用的各个因素,结合空战案例分析构造各个因素的优势函数,最后加权综合得到双方的优势指数,在此基础上采用模糊论域划分并加以组合的方法得到双方态势。通过大量的数字仿真,并与现有算法对比验证了该评估算法的有效性。     

某型机载预警雷达盲区计算模型研究

针对某型机载预警脉冲多普勒体制雷达本身的缺陷,对径向速度边界值进行计算,对盲区进行建模,对影响机载雷达盲区大小的各参数进行分析并进行仿真,结果表明模型能够准确地反映该型雷达的探测盲区.该模型已应用于作战训练,实践表明模型能帮助战勤人员了解战场态势,判断特定目标是否进入盲区,有利于战勤人员根据理论盲区指示采取相应的情报处理和协同处置措施,以便对重要目标进行跟踪和监视.如果敌方使用该型雷达,模型也可以作为突袭敌方目标时的理论基础依据.     

数据挖掘技术在供应链管理系统中的应用研究

本文在简要介绍数据挖掘的常用方法及其关联技术的基础上,重点论述了供应链管理系统中的数据挖掘体系结构,并以仓储管理中的库位选择问题为例给出了基于数据挖掘技术的供应链应用模型设计.     

Cooperative Communication Based on Spectrum Aggregation in LTE Further Evolution

The implementation of wide band radio transmission may occur in two parallel ways:designing a new system with larger bandwidth,or constructing a cooperative system based on existing systems.The former is a spectrum aggregation scheme based on multi-carrier transmission within one system,while the latter fulfills spectrum aggregation based on multi-carrier transmission among systems.On the one hand,the advantage of the multi-carrier transmission scheme within a system and among systems is that the existing R...     

基于ICA的AD样本的相关基因研究

为了克服每次运行独立成分分析算法(Independent Component Analysis.ICA)所得到不同的ICs对最后所选择的AD基因造成的不良影响,提出了一种应用ICA选择基因的改进方法.首先运行多次ICA算法,然后通过比较相关系数选出与AD相关的ICs,最后依据基因出现的频数选择相关基因.通过该方法寻找到39个在每个与AD相关的ICs 中都过表达的基因,且其中有一个基因位于X染色体上,通过理论分析和实验结果表明该算法的确是一种可行性的方法.     

TMS320C672x系列浮点DSP的EMIF研究与应用

针对如何灵活应用高性能32/64位浮点DSP TMS320C672x提供的性能优良的外部存储器接口(EMIF),分析了EMIF的特点和使用技巧,以TMS320C6722B型DSP为例,设计了EMIF与外部HY57V281620A型SDRAM和异步AM29LV80OBB-90EC型Flash的硬件接口,并分析了EMIF访问SDRAM和Flash时各控制寄存器配置的方法和具体步骤,列出了该配置命令下EMIF引脚与逻辑地址的对应关系和具体的软件编写例程;同时讨论了通过EMIF并行模式实现二次Boot的原理和方法,提出了在主程序直接烧写和用常用的FlashBurn工具烧写Flash的两种方法,并分析了二者的优缺点.实验证明,此研究方案设计合理、可靠并易于实现,针对TMS320C672x系列DSP具有通用性和可行性.     

Linear Size Optimal $q$-ary Constant-Weight Codes and Constant-Composition Codes

An optimal constant-composition or constant-weight code of weight w has linear size if and only if its distance d is at least 2w-1. When d ? 2w, the determination of the exact size of such a constant-composition or constant-weight code is trivial, but the case of d=2w-1 has been solved previously only for binary and ternary constant-composition and constant-weight codes, and for some sporadic instances. This paper provides a construction for quasicyclic optimal constant-composition and constant-weight codes of weight w and distance 2w-1 based on a new generalization of difference triangle sets. As a result, the sizes of optimal constant-composition codes and optimal constant-weight codes of weight w and distance 2w-1 are determined for all such codes of sufficiently large lengths. This solves an open problem of Etzion. The sizes of optimal constant-composition codes of weight w and distance 2w-1 are also determined for all w ? 6, except in two cases.     

基于作物茎杆生理电容式水分传感器的研究

准确检测作物生长的水分状况,对灌溉决策十分重要。本文介绍了作物茎杆生理电容式水分传感器的原理及电路设计,该传感器可实现对作物生长水分状况的无损检测,通过试验证明该电容传感器测量作物含水量的变化是可行的。基于茎杆生理电容变化的作物水分非破坏性检测技术,研制结构简单、测量准确、抗干扰能力强的作物水分测量传感器,对丰富节水灌溉技术和传感器技术具有重要的意义。     

基于ARM的直流系统接地故障检测应用程序设计

本文提出了基于S3C44B0X的直流系统接地故障检测装置的设计方案,并在此装置上实现了基于小波变换的检测方法,并重点阐述了应用程序的设计。