Secrecy performance analysis of AF relaying with relay selection scheme over Nakagami‐m fading channels

This paper investigates the secrecy outage probability (SOP) and intercept behavior for the amplify‐and‐forward network over Nakagami‐m fading channels. Relay selection schemes are evaluated. The optimal and suboptimal criterions require the instantaneous and statistical channel state information of the eavesdroppers' channels, respectively. The enhanced 2‐hop criterion needs the additional information of the target secrecy rate for relay selection. Theoretical analysis reveals that the diversity order of the SOP is dominated by the minimum fading figures of the source‐relay and relay‐destination channels, while that of the intercept probability depends on the fading figure of the relay‐destination channel. In the multirelay scenario, the optimal, suboptimal, and enhanced 2‐hop scheme achieve the same diversity orders of the SOP. For the intercept probability, the optimal and second‐hop relay selection schemes provide the same diversity order, while the diversity orders of the suboptimal and enhanced 2‐hop schemes are the same. Simulation results finally substantiate the accuracy of the theoretical analysis.     

基于m序列调制技术的叶绿素荧光检测系统设计

针对藻类叶绿素荧光信号微弱难以准确检测的问题,提出了基于m序列调制技术的叶绿素荧光检测系统。分析了荧光检测电路的噪声特点,设计了基于T型电阻反馈网络的I/V转换电路和二级放大电路;根据m序列解调原理,设计了双极性转换电路、移相电路和基于AD630的荧光信号解调电路。将系统应用于蛋白核小球藻叶绿素荧光检测,结果表明,对于叶绿素浓度为10 µg/L的蛋白核小球藻,测量相对标准偏差为2.61%。在0~100 µg/L叶绿素浓度范围内,检测系统输出直流电压值与蛋白核小球藻叶绿素浓度之间的线性相关系数达到0.998。     

嵌入式操作系统实践教学方法的探索

针对传统嵌入式系统实践教学与现实企业需求相脱节的问题,介绍一些嵌入式操作系统实践教学的内容和改进方法,提出一些基于μC/OS-II和智能手机linux内核的实践教学内容和项目.     

On the formation of interfacial and internal voids inα-Al2O3 scales

Microstructural observations were used as the basis for a discussion of the formation and growth of voids in alumina scales. Reactive-element additions to alloys and alloy desulfurization appear to inhibit the growth of interfacial voids, thus improving scale adhesion. This phenomenon is analyzed in terms of surface energies. In addition, a model is proposed for the formation of large internal voids in -A_l2O₃ scales. These voids appear to be too large to form as a result of vacancy coalescence and are more frequently observed in scales not doped with a reactive element. The model is based on a growth mechanism where inward and outward growing ridges at scale grain boundaries eventually seal off and form internal voids.     

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 60kg/m钢轨在运行一段时间后表面出现起皮缺陷。采用金相检验和低倍检验等方法对表面起皮钢轨的显微组织和低倍特征等方面进行了分析和研究。结果表明，起皮缺陷的形成是由铸坯角部裂纹和中间裂纹缺陷所引起的。提出了改进措施。     

百米定尺轨焊接生产线布局的探讨

结合南昌局向塘焊轨基地的现状进行相应的生产布局设计,对百米定尺轨的焊接工艺、生产布局进行了分析,提出了50 m工位间隔U字型百米轨焊接工艺布局的思路.     

基于Matlab的m序列的仿真与实现

m序列是一种典型的伪随机序列,它在扩频通信、流密码、信道编码等领域有着十分广泛的应用。本文介绍了m序列构造方法及基本性能,并利用Matlab中的Simulink仿真系统及M语言编程实现它们的产生和分析。仿真结果验证了该方法的正确性和可行性.     

基于模糊推理的Ti-Fe-Mo-Mn-Nb-Zr系钛合金性能预测及成分优化

考察了不同成分的Ti-Fe-Mo-Mn-Nb-Zr合金的压缩强度、硬度，得到了高压缩强度，硬度与牙本质相近的钛合金。在综合考虑钛合金成本、力学性能的基础上，采用模糊推理系统建立了钛合金中的元素质量百分含量与硬度之间的关系，并通过实验法进行了验证，预测结果与实际测定结果的对比是令人满意的。在保证性能的基础上，利用训练好的模糊推理系统对材料的成分进行优化，减少贵重元素的加入量。     

水平荷载作用下单桩的改进m法

关于桩受水平荷载作用的计算,m法运用较为广泛.由于m法是弹性地基法,当桩体位移过大时,不考虑土体的塑性特性,易造成大的误差.在m法计算桩受水平荷载作用的基础上,考虑桩的位移过大而造成土体的屈服,假定土体为理想弹塑性体,在桩体位移达到一定值时,土体对桩的作用力不再随位移的增大而变大.对m法进行了改进,且编制了改进法计算程...     

C8051F020终端温度监控研究

针对传统的检测方法不能及时了解工业现场实际的问题,提出了一种基于C8051F020的自热温度数据采集、传输、分析与处理策略,方便用户进行变量监测和信息管理.调用VB 6.0 ActiveX Mscomm通信控件在上位PC机和主控芯片之间实现串行通信,并将当前和历史数据显示在监控界面,供用户查询和打印.实验证明,受外界环境影响,历史温度平均值高出理论值15.64%.μC/OS-Ⅱ[1]在C8051F020微处理器上开发的终端温度监控软件已经通过了全面调试,通信稳定、数据可靠,达到了预期的设计目标.