浅谈光传输交换平台在长平高速的应用

目前,随着我国各地高速公路的发展,高速公路视频监控系统采用传统模式———传输采用光端机、交换采用模拟矩阵模式已突显瓶颈,越来越不适应现阶段高速公路的发展形势。通过对光传输交换平台与传统模式比较,及简述光传输交换平台在山西长平高速的具体应用,以期为我国高速公路发展提供参考。     

客运专线电力SCADA系统通信组网方案解析

研究目的:为保障客运专线供电的可靠性,各电力箱变需将现场信息传至电力SCADA系统中心进行分析处理,并接受中心下发的各种控制命令.而客运专线沿线电力箱变数量众多,传统的电力SCADA系统通信组网方案已不适应工程的实际需求.因此,研究出一个安全可靠、经济合理、技术先进的客运专线电力SCADA系统通信组网方案,并对其原理进...     

引气粉煤灰混凝土的氯离子扩散系数

基于盐碱寒冷地区的工程环境与混凝土的配制特点,模拟配制了SA溶液,采用正交方案试验研究了水灰比、含气量和粉煤灰掺量3个参数对引气粉煤灰混凝土氯离子扩散系数的影响,建立了氯离子扩散系数计算模型,并采用游程检验法对计算模型进行了检验,结果表明该模型表征的相关关系显著,预测值与实测值无显著差异。     

Application of new parameterizations of gas transfer velocity and their impact on regional and global marine CO2 budgets

One of the dominant sources of uncertainty in the calculation of air–sea flux of carbon dioxide on a global scale originates from the various parameterizations of the gas transfer velocity, k, that are in use. Whilst it is undisputed that most of these parameterizations have shortcomings and neglect processes which influence air–sea gas exchange and do not scale with wind speed alone, there is no general agreement about their relative accuracy.The most widely used parameterizations are based on non-linear functions of wind speed and, to a lesser extent, on sea surface temperature and salinity. Processes such as surface film damping and whitecapping are known to have an effect on air–sea exchange. More recently published parameterizations use friction velocity, sea surface roughness, and significant wave height. These new parameters can account to some extent for processes such as film damping and whitecapping and could potentially explain the spread of wind-speed based transfer velocities published in the literature.We combine some of the principles of two recently published k parameterizations [Glover, D.M., Frew, N.M., McCue, S.J. and Bock, E.J., 2002. A multiyear time series of global gas transfer velocity from the TOPEX dual frequency, normalized radar backscatter algorithm. In: Donelan, M.A., Drennan, W.M., Saltzman, E.S., and Wanninkhof, R. (Eds.), Gas Transfer at Water Surfaces, Geophys. Monograph 127. AGU,Washington, DC, 325–331; Woolf, D.K., 2005. Parameterization of gas transfer velocities and sea-state dependent wave breaking. Tellus, 57B: 87–94] to calculate k as the sum of a linear function of total mean square slope of the sea surface and a wave breaking parameter. This separates contributions from direct and bubble-mediated gas transfer as suggested by Woolf [Woolf, D.K., 2005. Parameterization of gas transfer velocities and sea-state dependent wave breaking. Tellus, 57B: 87–94] and allows us to quantify contributions from these two processes independently.We then apply our parameterization to a monthly TOPEX altimeter gridded 1.5° × 1.5° data set and compare our results to transfer velocities calculated using the popular wind-based k parameterizations by Wanninkhof [Wanninkhof, R., 1992. Relationship between wind speed and gas exchange over the ocean. J. Geophys. Res., 97: 7373–7382.] and Wanninkhof and McGillis [Wanninkhof, R. and McGillis, W., 1999. A cubic relationship between air−sea CO2 exchange and wind speed. Geophys. Res. Lett., 26(13): 1889–1892]. We show that despite good agreement of the globally averaged transfer velocities, global and regional fluxes differ by up to 100%. These discrepancies are a result of different spatio-temporal distributions of the processes involved in the parameterizations of k, indicating the importance of wave field parameters and a need for further validation.     

小型船用PEM燃料电池仿真特性分析

随着能源的逐渐枯竭和环境污染的持续加重,燃料电池的发展越来越受到世界各国的重视,燃料电池具有高效、清洁和环保等特点,特别是质子交换膜(PEM)燃料电池已经得到了广泛的应用。文章基于Matlab/Simulink软件平台,建立PEM燃料电池动态模型,以输入信号源作为外加负载,分析了随负载电流变化时,电池工作温度变化和阴阳极进气压力对PEM燃料电池输出电压和输出功率的影响。仿真结果与实际燃料电池特性曲线基本一致,所搭建的动态模型也能较好的反映PEM燃料电池的动态特性。     

水面舰艇作战系统的回顾和展望

  目的  舰船电子信息系统多方案优选是一个复杂的多属性决策问题。针对舰船电子信息系统的方案属性和权重信息不全、决策成员权重信息不全等问题,提出一种基于优势度测量和群体一致性的不完全信息舰船电子信息系统的方案优选方法。  方法  首先,提出不完全信息的交互准则,定义不完全信息情况下备选系统方案的绝对优势、严格优势和弱优势关系;然后,定义群体优势度指标,提出在不完全信息工况下实现备选方案全序关系的计算方法;最后,以某舰船电子信息系统方案优选为例,开展案例分析。  结果  通过群体一致性计算和迭代,形成了满足决策群成员一致性要求的优劣排序结果,验证了优选方法的合理性和有效性。  结论  研究成果可为信息不完全工况下舰船电子信息系统多属性方案优选提供技术支撑。     

SETBOC协议分析及其再改进方案

基于单向身份认证技术的安全电子交易协议SETBOC(Secure E lectron ic Transation Based onOne-way Certification)具有效率高,易实现的优点,分析了SETBOC改进方案的优点和不足。在保留原协议及其改进协议优点的基础上,提出再改进方案,使SETBOC协议满足非数字商品交易的原子性。再改进后的协议保证了商家与顾客的交易更加公平。     

Surface CO2 measurements in the English Channel and Southern Bight of North Sea using voluntary observing ships

Ships of opportunity have been used to investigate ocean–atmosphere CO₂ fluxes in the English Channel and Southern Bight of the North Sea. Continuous underway measurements of the fugacity of seawater carbon dioxide (fCO₂^sw), chlorophyll, temperature and salinity have been performed along 26 transects during the spring and autumn periods. The spatial fCO₂^sw distribution along the Channel and Southern Bight is modulated by the photosynthetic activity, temperature changes and water mixing between inputs from the North Atlantic Ocean and riverine discharges. The seasonal variability of fCO₂^sw is assessed and discussed in terms of the biology and temperature effects, these having similar impacts. The variation of fCO₂^sw shows similar interannual patterns, with lower values in spring. The annual average of air–sea CO₂ fluxes places the English Channel as neutral area of CO₂ uptake. The spring and autumn data allow differentiating between distal and proximal continental areas. The Southern Bight shows a tendency towards net CO₂ uptake on the distal continental shelf, whereas the Scheldt and Thames Plumes show a CO₂ source behaviour on the proximal continental shelves.     

中国铁通部署网络智能化的思路探讨

在传统的PSTN网上开展全新业务时往往遇到网络制约问题，实施网络智能化，可以将所有呼叫上传到智能网处理，有可能集中管理用户数据，给用户带来全新的业务体验，运营管理更加便捷。从中国铁通的实际出发，探讨了部署网络智能化的思路。