64-QAM传输系统的Optisystem仿真设计

64-QAM是一种高效的数字调制方式,广泛应用于各种通信系统中。首先对64-QAM的调制/解调原理进行了理论研究,然后借助Optisystem光仿真软件,搭建了64-QAM传输/接收模型,并对模型的接收和发射模块进行了详细的分析,最后对模型的传输性能进行了仿真验证。仿真结果表明,接收端64-QAM的星座图清晰,即64-QAM调制格式能有效地实现数据信号的传输,该模型能为实际的工程设计提供理论上指导。     

64DAPSK-OFDM与64QAM-OFDM系统性能比较

针对OFDM系统中的MQAM和MDAPSK两种子载波高阶调制技术,介绍了64QAM和64DAPSK信号的比特软输出解调方法,比较了64DAPSK-OFDM和64QAM-OFDM系统的误码性能。仿真结果表明,在频率选择性和时间选择性衰落信道下,若信道相邻子载波或相邻OFDM符号的相关性能得到保证,采用64DAPSK调制可以用较少的信噪比损失换取OFDM系统复杂度的大大降低。     

Co64Fe11Nb5Si12B8合金磁导率与温度的关系

采用铁芯测试仪测得合金样品的初始磁导率随温度的变化曲线, 用磁化强度小角旋转法测量非晶及晶化合金条带的饱和磁致伸缩系数λs;研究了不同温度退火后Co64Fe11Nb5Si12B8合金的磁导率随温度的变化、磁性以及磁致伸缩系数;结果表明:合金在580、590℃热处理磁性变好的反常现象是由于磁致伸缩系数变小所致.     

基于HTTP协议多维随机参数插入通信隐藏算法

基于HTTP协议参数插入的信息隐藏算法可以将待隐藏的信息嵌入到目前Internet上使用最为广泛的协议数据包中,逃避防火墙等网络安全工具拦截和窜改。经过试验总结出了,为了增强通信的隐秘性,算法设计需要考虑的一些问题。提出了一种多维随机插入算法,增加了通信的隐秘性。为了进一步增加隐秘性和可靠性,待隐藏信息在隐藏之前进行了加密和数字摘要计算。同时针对嵌入算法多维随机性,计算该隐蔽信道的带宽模型,并在试验中进行了验证。     

低温SOFC用阴极材料LaNi0.6Fe0.4O3

用固体氧化物燃料电池技术,考察了钙钛矿型氧化物LaNi0.6Fe0.4O3(LNF-64)作为阴极材料在低温(400℃、500℃)下的电化学性能,以复合材料[Ce0.8Sm0.2O2-δ(SDC)和碳酸盐(Na2CO3和Li2CO3)]为电解质,分别以NiO和LNF-64为阳极和阴极.结果表明,通过碳酸盐共沉淀法得到的LNF-64前驱体粉末,在900℃下煅烧4 h,形成了单一的菱形结构,粉末粒径约为300～500 nm.单体电池在500 ℃下的最大功率密度和短路电流密度分别为213 mW/cm2和720 mA/cm2.     

64排CT在糖尿病下肢动脉硬化闭塞症中的应用

目的:探讨64排CT在糖尿病下肢动脉硬化闭塞症中的应用.方法:选择我院收治的糖尿病下肢动脉硬化闭塞症患者86例,先进行64排CT扫描(CTA),后再进行数字减影检查(DSA),比较两种方法诊断的准确性和血管病变检查情况.结果:CTA对下肢血管病变准确范围、部位等显示清晰.其检测的敏感性显著高于DSA,P<0.05.且前...     

基于C8051F120的可燃气体无线报警系统设计

介绍一种基于Silicon Lab公司的C8051F120单片机设计的可燃气体无线报警仪,并阐述了报警平台的软硬件设计。无线报警系统由报警器和报警平台两部分组成,两者通过射频芯片SI4432实现数据的无线传输,并由报警平台上的GR64模块通过GSM网络以SMS方式实现远程报警功能。测试结果表明:该系统性能稳定、抗干扰能力强,具有很高的应用价值。     

Mechanics of Oil Sands Slurry Flow in a Flexible Pipeline System

Slurry transportation is an economic haulage system in oil sands and coal-mining operations characterized by long haulage distances and rugged terrain. In such conditions, the ton-km-hr limits are exceeded creating extreme tire wear and high maintenance costs. Steep haul grades and rugged terrain also cause mechanical wear and tear, which decrease haulage equipment economic life. Hydraulic transportation is a proven and viable technology for slurry transportation in such conditions. Currently, stationary pipeline transportation is being used in transporting minerals in many mines. There is an increasing demand to create slurrified minerals at the mining faces to be transported to the processing plant. However, stationary pipelines are not capable for dealing with the rapidly changing configuration of the mining faces. In this paper, the authors develop the ground articulating pipeline (GAP) technology to address this problem. The GAP system consists of pipelines connected together with flexible joints in each pipe section, which allows deflection to avoid torsional stresses from the adjoining frames. This flexible arrangement accommodates the horizontal and vertical displacements of the mobile system as it follows the hydraulic shovels in the excavation process. The mechanics of the GAP system, as well as the production–economic function, are formulated and simulated over an extended period using data and information from Syncrude’s North Mine. The results show that the GAP system is technically and economically viable for productivity between 6,300 and 6,500 tons per hour. The simulated head loss for the GAP system is 15.66 m per 400 m, which compares with 20 m per 400 m for the existing stationary system at Syncrude. The pressure gradient-radius curves are asymptotic to the pipe boundaries, which indicates steep axial pressure gradient in these areas.     

高速数据传输中64DAPSK解调的简化算法

提出了一种简化的解调算法,与常规的解调算法相比,这种算法简单、容易实现,且误码率和传统算法相比几乎没有降低,使64DAPSK实现难度得到简化.仿真了本算法和传统算法误码率的比较结果,以及几何平均数和代数平均数作为幅度阈值解调的误码率比较结果.