高速铁路环境中无线信道传输特性的探讨

在高速铁路环境下，无线信道的性能发生急剧的变化。针对高速环境下电波传播的特点，阐述了高速铁路中无线信道的特点并对无线信道进行了建模，分析了高速铁路中多普勒频移的特性及对误码率的影响，讨论了隧道传播环境，最后对无线传输的可靠性进行了分析。     

Validation of the 3D biogeochemical model MIRO&CO with field nutrient and phytoplankton data and MERIS-derived surface chlorophyll a images

This paper presents results obtained with MIRO&CO-3D, a biogeochemical model dedicated to the study of eutrophication and applied to the Channel and Southern Bight of the North Sea (48.5°N–52.5°N). The model results from coupling of the COHERENS-3D hydrodynamic model and the biogeochemical model MIRO, which was previously calibrated in a multi-box implementation. MIRO&CO-3D is run to simulate the annual cycle of inorganic and organic carbon and nutrients (nitrogen, phosphorus and silica), phytoplankton (diatoms, nanoflagellates and Phaeocystis), bacteria and zooplankton (microzooplankton and copepods) with realistic forcing (meteorological conditions and river loads) for the period 1991–2003. Model validation is first shown by comparing time series of model concentrations of nutrients, chlorophyll a, diatom and Phaeocystis with in situ data from station 330 (51°26.00′N, 2°48.50′E) located in the centre of the Belgian coastal zone. This comparison shows the model's ability to represent the seasonal dynamics of nutrients and phytoplankton in Belgian waters. However the model fails to simulate correctly the dissolved silica cycle, especially during the beginning of spring, due to the late onset (in the model) of the early spring diatom bloom. As a general trend the chlorophyll a spring maximum is underestimated in simulations. A comparison between the seasonal average of surface winter nutrients and spring chlorophyll a concentrations simulated with in situ data for different stations is used to assess the accuracy of the simulated spatial distribution. At a seasonal scale, the spatial distribution of surface winter nutrients is in general well reproduced by the model with nevertheless a small overestimation for a few stations close to the Rhine/Meuse mouth and a tendency to underestimation in the coastal zone from Belgium to France. PO₄ was simulated best; silica was simulated with less success. Spring chlorophyll a concentration is in general underestimated by the model. The accuracy of the simulated phytoplankton spatial distribution is further evaluated by comparing simulated surface chlorophyll a with that derived from the satellite sensor MERIS for the year 2003. Reasonable agreement is found between simulated and satellite-derived regions of high chlorophyll a with nevertheless discrepancies close to the boundaries.     

深圳港铜鼓航道超大型集装箱船航行限制条件研究

文章以某集装箱船舶为例,根据深圳港铜鼓航道目前航道宽度及水深来确定该集装船安全通过铜鼓航道的限制性条件,从而为超大型船舶安全通过铜鼓航道提供方法依据,具有一定的借鉴意义。     

日本关门海峡航行航法研究

文章针对关门海峡的地理位置、水文气象、航道碍航物、海峡内港口、导航信息、报告制度、通航信号显示等情况进行了论述,并根据多次通过关门海峡的经验总结出一些航行航法建议,以供航经该区域的中国籍船舶自引驾驶员参考。     

抚远水道大桥方案设计

抚远水道位于抚远县境内,地处黑龙江、乌苏里江两江汇合处的黑龙江主槽及其汊江之间。打通抚远水道,建设抚远水道大桥,对促进中俄经济合作,开发黑瞎子岛,带动抚远地区的经济腾飞,都有着重要的意义。详细介绍了大桥的桥位、桥型选择,供技术同行参考。     

渤海湾公路通道与世界实例

对渤海湾公路通道的三个方案进行介绍,并分析优缺点,同时列举了世界范围内的大型跨海工程进行参照,最后提出一些可行的建议.     

基于DCA原理的车道动态分配控制策略

在城市道路交通系统中,由于机动车出行量的不断增长,使得现有道路资源、传统的交通控制及组织方式已无法满足出行者的需求。通过对城市道路交通系统与TD-SCDMA系统的共性进行分析,借鉴TD-SCDMA系统中DcA的原理,并结合现有道路资源分配方法,提出车道动态分配的新思路。在此基础上,分析基于双重缓冲车道和基于部分共享资源的双阈值车道预留动态分配策略。     

荆州市豉湖渠排涝泵站工程设计

该文通过湖北省荆州市豉湖渠排涝泵站工程,介绍了该泵站规模的确定、站址的选择、工程布置以及主要构筑物的设计,可供类似工程参考。     

武汉长江隧道盾构段结构型式研究

武汉长江隧道是我国在高水压、强透水地层中修建的第一条大直径盾构隧道,且左侧河床历年冲淤变化幅度较大,如何选择合理的隧道结构型式是工程设计必须考虑的关键问题.为此,在国内外现有单层管片衬砌和全环双层衬砌的基础上,研究提出了一种新型的“管片衬砌+非封闭内衬”的双层衬砌结构该结构在不增加隧道开挖直径的前提下,允分利用圆形隧道底部和两侧的富余空间现浇钢筋混凝土,并与车道板结构共同组成非封闭二次衬砌结构,可以大幅度地减少河床冲淤变化时的结构横向变形,并确保隧道底部与两侧这些重点部位的防水性能及结构长期稳定性,是一种值得推荐的创新结构方案.     

航标自动监控系统研讨

本文简述了航标自动监控系统的重要性、框架结构、基本组成和监测内容．对系统的作用距离、可用性、可靠性和我国组建该系统的基本条件等进行了研讨。作者认为,我国组建航标自动监控系统不但必需,而且可行