Pre-processing for time domain image formation in SS-BSAR system

A pre-processing procedure is designed for a space-surface bistatic synthetic aperture radar (SS-BSAR) system when a time domain image formation algorithm is employed. Three crucial technical issues relating to the procedure are fully discussed. Firstly, unlike image formation algorithms operating in the frequency domain, a time domain algorithm requires the accurate global navigation satellite system (GNSS) time and position. This paper proposes acquisition of this information using a time-and-spatial transfer with precise ephemeris and interpolation. Secondly, synchronization errors and compensation methods in SS-BSAR are analyzed. Finally, taking the non-ideal factors in the echo and the compatibility of image formation algorithms into account, a matched filter based on the minimum delay is constructed. Experimental result using real data suggest the pre-processing is functioning properly.     

Capacitated stochastic coloured Petri net-based approach for computing two-terminal reliability of multi-state network

Classical network reliability problems assume both networks and components have only binary states,fully working or fully failed states.But many actual networks are multi-state,such as communication networks and transportation networks.The nodes and arcs in the networks may be in intermediate states which are not fully working either fully failed.A simulation approach for computing the two-terminal reliability of a multi-state network is described.Two-terminal reliability is defined as the probability that d units of demand can be supplied from the source to sink nodes under the time threshold T.The capacities of arcs may be in a stochastic state following any discrete or continuous distribution.The transmission time of each arc is also not a fixed number but stochastic according to its current capacity and demand.To solve this problem,a capacitated stochastic coloured Petri net is proposed for modelling the system behaviour.Places and transitions respectively stand for the nodes and arcs of a network.Capacitated transition and self-modified token colour with route information are defined to describe the multi-state network.By the simulation,the two-terminal reliability and node importance can be estimated and the optimal route whose reliability is highest can also be given.Finally,two examples of different kinds of multistate networks are given.     

列车运行监控装置文件丢失故障探讨

列车运行监控装置是确保列车安全运行的重要设备,具有监控和记录两大功能,如果记录文件丢失,将给后续的分析工作造成不便,为列车安全运行造成隐患。针对列车运行监控装置记录文件丢失故障问题,分析了故障产生的原因,探讨了解决办法。     

浅析RTK技术在地形测量中的运用

介绍了RTK的3种测量模式,通过分析RTK技术对临汾市地形进行测绘的实战作业,总结出常规作业模式的特点。     

暂准进境货物内销缓稅利息计征与否之决定因素探究

暂准进境货物进境后的状态有加工、储存和使用三种,在不同状态下的暂准进境货物有的内销需征收缓稅利息,有的则不征收。通过对各类暂准进境货物的异同、状态变化和对税收优惠政策的利用情况进行分析,结果表明:暂准进境货物内销缓稅利息计征与否的关键因素是公平原则的要求,即缓税利息制度存在与执行的意义所在。     

浅谈寒冷地区大体积砼冬季施工技术

文章重点介绍了寒冷地区侯家沟大桥承台大体积砼施工技术方案及实施工艺.     

An advanced algorithm of electrical capacitance tomography

We describe a new two-phase flow electrical capacitance tomography algorithm of image reconstruction which is based on 12-electrode capacitance transducers. According to the result of computer simulation, this algorithm is able to greatly increase the imaging fidelity without decreasing the imaging velocity. Supported by the Natural Science Foundation of Guangdong Province (No. 950490) Yan Jie: born in 1969. Ph.D.     

综合录井仪实时软件的设计及应用

设计了一种监测钻井参数的实时软件系统。这种软件系统采用汇编语言,并启用8087(或80287)数值处理器,用汉字显示,便于数据监测与采集,钻井动态数据可直接存储在磁盘上,随时监测钻井工况。现场使用证明,该程序能满足钻井工程需要。文中论述了软件系统的功能设计原理,分析了钻井参数的变化情况及确定方法,介绍了数据转换模块的特点。     

单电容有源带阻滤波器

这种新型的有源滤波器,只用一个电容器、一个运算放大器和两个电阻器。该电路能实现带阻和低通滤波特性,其极点品质因数可以独立调整而不影响其它参数。文中给出了实验结果,证明了理论分析的正确性,分析了在中心频率处阻带衰减为有限值的原因,认为这是运放附加相移的影响。     

豚草传播特性的初步观察

豚草具有很强的生态适应性,其种子萌发受温度的制约明显,豚草从侵入某一地区到进入稳定阶段以前,其群聚度往往与侵入时间的长短呈正相关,当外界阻力达到或接近足够阻止豚草种群在该地区的继续扩展时,此种群就进入了稳定阶段。建议采取综合防除措施。