高速电气化铁路的接触网电分相型式探讨

根据目前关节式电分相存在问题，提出一种新型的3个绝缘锚段关节双中性段关节式电分相型式，有效地克服了目前双锚段关节单中性段关节式电分相存在的问题，可较好解决关节式电分相对电力机车受电弓多弓运行条件的限制。     

Spatial distribution of cadmium over a cyclonic eddy in the southern East China Sea

Eddy systems are a unique ecosystem, usually having high biological masses and primary production in the sea. In this study, both particulate and dissolved phases of cadmium in the water column of 15 stations over a cyclonic eddy in the southern East China Sea were determined to obtain their spatial distributions. This allows us to confirm that cyclonic eddy systems play the role of a Cd pump in the sea.Results showed that particulate Cd (PCd) and dissolved Cd (DCd) concentrations in water varied greatly, ranging over two orders and one order of magnitude, respectively. Large spatial variability was found not only for PCd but also for DCd in the upper water, apparently due to the effects of the cyclonic eddy system on the Cd distributions over the study area. DCd accounts for about 99% of the total Cd. For the surface water, DCd concentration at the eddy center was about five times the average of the water surrounding the eddy center. The depth distributions of DCd exhibited a typical surface depletion and a subsequent increase with depth; however, the PCd distribution showed the opposite, i.e. a surface maximum and a subsequent decline with depth. In general, the DCd maxima were found at depths of 600–1000 m, agreeing well with the literature. It reflected the internal biogeochemical cycling of Cd in the water column, which was driven by the utilization of Cd by plankton in the euphotic zone and by the regeneration of Cd at depth. In addition, a remarkably high DCd concentration existed in near-bottom water around the cyclonic eddy center.The horizontal distributions of both PCd and DCd in the upper water shared a common feature with elevated concentrations centering around the eddy center and a decline in concentration with distance from the eddy center. This shows that the cyclonic eddy could bring up the Cd-rich deep water to the surface water around the eddy center and could then expand toward eddy's vicinity via advection–diffusion. It is thus likely that it produces ample biological masses over the eddy system. Hence, this work can demonstrate that the ascending nutrient-rich water driven by the cyclonic eddies can serve as an important source not only for many nutrients but also for Cd in the sea.     

杭州市道路交通高峰拥堵成因分析与对策研究

该文首先对交通拥堵的时空特征进行系统总结,从交通供给(路网、公交、停车、交通管理)与交通需求(人口与用地功能分布、小汽车拥有量与使用率)两方面分析了交通拥堵形成的深层次原因。在此基础上,从城市空间结构调整、交通出行结构调整、基础设施的功能提升与结构完善、管理科学化、长效交通评估机制的建立等角度,提出对杭州市交通拥堵应对策略的建议。最后指出,改善城市交通拥堵状况将是一项长期而艰巨的系统工程,任何急功近利的"头痛医头、脚痛医脚"的短期行为都无助于交通拥堵的有效缓解,交通结构的优化调整及合理的交通需求管理才是最终缓解交通拥堵的有效手段。     

连续相位调制信号的检测

本文主要介绍了CPM信号的解调方法,研究了基于最大似然接收原理的网格搜索最优算法—维特比（viterbi）算法,并且通过Matlab计算机仿真,给出了一定信噪比条件下影响CPM调制体系误码率性能的因素。     

舰船惯导航行数据的重构及混沌特性分析

针对现有舰船航行数据处理研究中,对数据内在属性及不同数据间相关性研究不够深入的问题,应用不同方法对舰船惯导航行数据进行了相空间重构及比较分析。分析结果表明,C-C方法对船舶惯导航行数据的重构效果较好。在此基础上,进行了惯导数据的混沌特性定性分析,并计算了惯导数据的最大Lyapunov指数,对舰船惯导数据进行了混沌动力学特性研究。分析结果证实了舰船航行数据具有较为典型的混沌特性,为进一步研究采用混沌控制等方法对舰船航行中的混沌状态进行控制提供必要的数据基础和比较依据。     

二相流模式下JDC4-55可调桨粘性流场分析

运用CFD方法中的汽-液混合二相流模型模拟JDC4-55可调桨的水动力性能和空泡性能。通过改变进速和调节桨叶角度得到相应的水动力性能参数。分析空泡对螺旋桨水动力性能的影响,进行JDC4-55可调桨桨流场模拟分析。相对于单相流模型而言,JDC4-55可调桨汽-液混合二相流模型性能计算结果与实验值吻合得更好。     

水下地形辅助导航新方法仿真

水下地形辅助导航是水下运载体导航定位技术研究的关键技术之一。传统的水下地形辅助导航采用回声测深仪,导航定位精度低,有时甚至失效。本文将多波束测深引入水下地形辅助导航,将水深映射为灰度值,利用快速傅立叶变换将输入灰度图从空间域变换为频率域。先采用相位相关技术进行粗匹配,再采用图像Hu不变矩特征进行精匹配,实现导航定位。对基于不同实验获取的实测海底地形图、惯性导航数据、DGPS数据以及多波束实测数据进行了实验室仿真。仿真结果表明,新方法可以极大地提高水下地形导航定位精度,使INS误差降低到原误差的15%以内,尤其是在INS初始误差较大时(小于3 km)导航定位精度改进更好。     

长洲枢纽双线船闸堵船原因分析及对策

文章阐述了长洲双线船闸运行3 a来的堵船滞航现象,对其主要原因进行了分析。同时提出了具体措施,包括航道整治及相关配套工程建设,扩建三线四线船闸,建立高效的协调机制,联合调度枢纽水库,协调发电、调水和压咸补淡调水等各方利益。