适于双周期的干道绿波信号协调控制模型

针对现有双周期干道绿波信号协调控制方法存在的不足,首先推导了适于双周期 协调控制的等式约束条件,其次详细分析了现有研究成果存在的缺陷,再次以双向权重绿波 带宽之和最大为优化目标,建立了适于双周期协调控制的绿波协调控制模型;最后以义乌市 望道路为例,利用VISSIM 仿真平台对比本文模型与改进MULTIBAND模型生成的协调控制 方案之间的优劣.仿真结果对比表明,相比于改进MULTIBAND模型,本文模型生成的协调控 制方案在高、中、低交通需求下均能够有效减少平均延误时间与停车次数,从而验证了本文所 建模型的有效性与实用性.     

真空装置在复杂舱底水扫舱系统的应用

本文以3 000m深水铺管起重船为依托,阐述了真空装置在复杂舱底水扫舱系统中的应用。     

大吨位T形刚构桥转体施工风险评估与对策研究

大吨位T形刚构转体桥施工作业技术难度大,不确定因素多,对其施工过程展开风险评估研究非常必要。根据风险评估与管理理论,利用综合识别法识别出转体过程中的施工风险因素,并对转体过程的主要风险源进行风险评估,提出相应施工风险控制对策,为今后类似桥梁施工管理及风险评估提供借鉴。     

高速公路分离式路基桥梁预制场施工技术

以常张高速公路某段分离式路基桥梁预制场施工为例,从布设、施工方案和人力、物力安排等方面,探讨了如何在短工期内,节约造价并高质量地完成施工,为同行提供参考.     

Shafting coupled vibration research based on wave approach

Because of propeller hydrodynamic influence, the shafting vibration is a coupled vibration which includes torsional, longitudinal and whirling vibrations. It is unsuitable to analyze different vibrations of propulsive shafting systems with development of shipbuilding technologies. To overcome the shortages of traditional marine standards, we establish a new numerical model of the shafting coupled vibration. And we put forward shafting coupled vibration calculation to ensure better reliability of main propulsion system. The shafting system is modeled into two sub-systems, a continuous one and a discrete one. Wave approach and transit matrix method are used to investigate displacement and stress fields in continuous and discrete sub-systems, respectively. And vibrations of different modes in both sub-systems are coupled by using dynamic equilibrium and continuity condition to deduce the global equations governing the motion of shafting. The coupling calculation is then used to research the reason of a very large crude carrier （VLCC） stern hull vibration. It is shown by the comparison of the results from both coupling and dependent vibration calculations that vibration in deferent directions will cause deformation in the same mode, which leads to extra stress and displacements on shafting, especially as the resonant frequencies of different vibration modes match each other. This is helpful to prevent ship stern vibration due to poor shafting vibration calculation.     

Protective effect of glutamine pretreatment on ischemia-reperfusion injury of spinal cord in rabbits

Objective To investigate the effect of glutamine (Gln) on the content of reduced glutathione hormone (GSH) and aminoglutaminic acid (Glu) of spinal cord following ischemia-reperfusion injury. Methods Totally 40 healthy adult male rabbits were randomly divided into five groups: sham-operation group (S group), ischemia-reperfusion injury group (I/R group), low-dose glutamine group (L Gln group), median-dose glutamine group (M Gln group) and high-dose glutamine group (H Gln group). After glutamine preconditioning, the model of spinal cord ischemia-reporfasion injury was established according to Zivin's method. The general status of animals was observed and the changes of Jacobs scoring were recorded in each group. Malondialdehydes (MDA), GSH, Glu and superoxide dismutase (SOD) activity in lumbar spinal cord tissues were determined using chemical colorimetry. The neuron number and deviation rate in spinal cord anterior horn were observed histopathologically. Results There was no significant difference between L Gin group and I/R group in behavior scoring, SOD activity, content of MDA and Glu, neuron number and deviation rate of spinal cord (P>0.05); however, there was a significant difference in GSH content of spinal cord (P<0.05). M Gln group and I/R group differed significantly (P<0.05) in behavior scoring, SOD activity, content of MDA, Glu, GSH, neuron number and deviation rate of spinal cord. Between H Gln group and M Gln group, there was no significant difference in behavior scoring, content of MDA and Glu, SOD activity, neuron number and aberration rate in spinal cord (P>0.05), whereas there was a significant difference in SOD activity and Giu content (P<0.05). Conclusion Pretreatment with medium-dose glutamine has a protective effect on spinal cord ischemia-reporfasion injury in rabbits, which may be related to the maintenance of GSH content, increase of SOD activity and reduction of MDA.     

船舶多学科设计优化中的船型变换模块

为了实现船型优化,第一步需要按照设计变量的改变来生成船型,这样就需要一个变换程序将母型船变换成设计船.当船型优化发展到基于CFD以后,传统的通过主尺度和几个船型参数例如Cp,Cw等来控制船体型线的做法已经不能满足要求,需要对船型进行更加准确,细致的控制.为了解决这个问题,文中开发了一个新的船型变换程序,它直接读人横剖面面积曲线和设计水线,然后变换船体型线以满足这两根曲线的要求.该程序的变换步骤包括主尺度仿射变换,Cm变换,横剖面面积曲线变换和设计水线变换.程序中主要的变换方法为广义Lackenby变换,仿射变换等.该程序由于直接根据横剖面面积曲线和设计水线来控制型线,使船型变换模块的设计变量从10个左右扩展到了40个以上,增加了船型优化提升船体性能的可能性.该程序是船舶多学科设计优化的船型优化模块的前处理程序.     

多媒体教学在航海类专业英语教学中的应用

加入WTO后伴随着海运外贸运输量的大增,给我国航海业带来了巨大商机.而世界海员劳务市场的东移,为我国的航海教育带来了不可多得的契机.运用多媒体教学方式的灵活性与多变性,可以提高专业教学的效果.     

重庆跨坐式单轨交通整体夹持T型汇流排的研究

重庆较新线原有T型汇流排在运行过程中暴露出接触线与汇流排接触电阻增大、汇流排焊接工艺复杂等缺点.采用整体夹持T型汇流排,汇流排之间采用联接板连接的方式进行安装,有效地克服了原汇流排的缺点,同时保持了与原有系统零部件100％的兼容性.     

城市轨道交通综合监控系统的RAMS管理

综合监控系统已日渐成为城市轨道交通自动化系统中的一种基本系统.为了保证综合监控系统可靠安全地工作,可靠性、可用性、可维修性、安全性( Reliability、Availability、Maintainability and Safety,简为RAMS)管理规范已逐渐被应用到城市轨道交通的自动化控制领域中.介绍了城市轨道...