SDG密度仪填土压实度检测试验

SDG密度仪是一种基于电磁学原理的密度检测仪,在用于路基填土压实度检测过程中,可进行现场压实填土密实度的快速无损检测,从而实现对现场填土压实质量的动态实时检验与控制。根据密度仪的特性实施现场与室内模拟试验,结果显示SDG密度仪具有良好的稳定性与可靠性,适合于黏性填土密度的快速无损检测,尤其是对于干密度为1.5 g/cm3以上的黏性填土显示良好的准确性与可靠性。     

国外市域轨道交通共线运营方式的发展和启示

给出了城市轨道交通共线运营的定义.介绍了国外轨道交通共线运营的概况.从制式分类方面可将共线运营方式分为:不同投资主体的线路共线运营;制式不同线路的共线运营;岔线形态的不同线路共线运营.分析了在市域轨道交通实施共线运营方式的利弊.上海市域轨道交通线路规划应充分考虑共线运营的可能性     

基于波数积分的点声源海底地震波计算方法研究

将舰船地震波简化为液固多层半无限空间低频点声源引起的地震波动问题,基于波数积分方法,通过FFP数值积分求解了海底表面声压、位移和加速度幅值,得到了海底表面声压、位移和加速度的频率特性曲线.对硬质和软质两种海底条件下远场海底地震波信号特征的分析结果表明:随频率增大,海底表面声压的传播损失逐渐增加;软质海底的位移、加速度总体上比硬质海底大;和硬质海底相比,软质海底更有利于声源较低频率成分的传播.     

Viscous micropump simulation by particle/continuum methods

A novel viscous micropump consisting of a cylindrical rotor eccentrically placed inside a microchannel is simulated by the two Volume-CAD (V-CAD) framework-based flow solvers, i.e., the direct simulation Monte Carlo (DSMC) package (named as V-DSMC) and the Navier-Stoke solver (named as V-Flow). V-DSMC is used in the case of the pump applied to gas, while V-Flow is applied to model the pump in the case of liquid working medium. The pumping performance curves under different liquid media with the variation of Reynolds number, as well as under different eccentricity factors are obtained. The performance and the flow filed characteristics are very sensitive to the tangential momentum accommodation coefficient in the case of gas medium. Three recirculations exist in the flow field, and the sizes of recirculation are different at the different operating points in a performance curve.     

一类二阶二次差分方程的动力学分析

针对一类可化为不可逆映射系统的二阶二次差分方程,应用二维不可逆连续叠映射动力系统理论研究其动力学行为.分析该映射系统不动点的局部稳定性及其分叉,运用不可逆映射的关键集理论研究该映射系统关于有限吸引集的吸引域的全局分叉问题.     

客运专线基础设施维修管理体系信息化建设方案探讨

客运专线的综合维修是列车高速、高密度、安全、平稳运行的保障。建立高效率、高质量、低成本的综合维修体系,按照统一指挥、协调工作、协同作业的方式进行综合维修,必须采用当前先进、成熟的信息技术建设客运专线基础设施综合维修管理信息系统,实现信息传递快捷、信息沟通及时、信息统计分析准确、信息共享高效等目的,为实现＂高质量、高效率、少用人、低成本＂的综合维修目的、应急应变快速反应和服务行车安全提供充分的技术支撑手段。     

上海市中心区常规公交线网调整策略研究

上海在大规模建设城市轨道交通线网之后,城市公交线网需要大幅度调整,中心区的公交线网会有结构性的变化.本文分析了上海市中心城区公交线网存在的问题,剖析了东京、巴黎的中心区公交线网的规模、结构和线路布设等特征.借鉴东京、巴黎的公交线网布设经验,结合上海市中心区公交线网的供需特点,提出了上海市中心区公交线网3种调整策略:减少...     

基于DSP的多普勒无线电引信检测系统设计

文章在介绍了TMS320LF2407芯片的性能参数后,利用其实时控制能力对无线电引信性能进行实时检测。文中对该系统的硬件和软件进行了设计。并将其应用到实际的实验中,试验结果表明该检测系统基本实现了既定的目的,缩短测试时间,为引信战时的稳定性提供了一定保障。     

建筑物的变形观测方法及常见问题的处理

对建筑物变形观测的常用方法、沉降原因进行了讨论,并分析了沉降观测中常见的问题及其处理方法。     

Causality of future and spot grain prices between China and the US: Evidence from soybean and corn markets against the surging import pressure

As the boom of the world grain market phases out, the challenge for Chinese government has gradually moved from retarding grain exports to restraining imports. This study tries to examine the causalities of soybean and corn price movement among the United States (US) future market, Chinese domestic future market and Chinese spot markets. We find that the daily prices of all these three types of grains belong to I(1) series, and there are long-run integrations. Also Chinese soybean future prices adjust more quickly than its spot prices, while Chinese corn future prices adjust slower. This paper finds that the soybean price movement originates from the US future market, then passes through Chinese future market, and finally reaches Chinese spot market, while the corn price movement starts in Chinese spot market, then spreads to the future markets in both China and the US. Finally, this paper also provides some policy implications on how to release the pressure from the grain imports.