Experimental Study on Turbulent Width around Bridge Piers

Introduction The fluid state near a bridge pier usually changesshortly after the new bridge is built. The unsafe navi-gational area around the bridge pier, where the shipcollisions against bridge piers frequently occur, is de-scribed by turbulent width.Ch…     

混合动力电动汽车ISAD电机控制电路研究

设计了一种新型混合动力电动汽车的电机控制电路,控制电路由电机电压控制电路和PWM脉宽调制电路构成.电机电压控制电路由功率放大电路和H型双极驱动电路组成.以芯片UC3637为核心构成的PWM脉宽调制电路模块用来产生PWM脉冲;以IR2110对称构成的功率电路模块用来进行功率放大;以场效应管IRF640构成的H型双极驱动电路模块用来驱动电机.利用所设计的电机控制电路,进行了电机的线性度和助动转矩等性能试验.结果表明,完全满足混合动力电动汽车性能要求.     

WMTC摩托车排放标准的试验验证及分析研究

通过对WMTC世界摩托车排放标准进行比对试验和验证得出:WMTC标准采用的驾驶循环,能真实反映摩托车在路面上的实际行驶过程及摩托车的实际排放水平;WMTC标准采用的驾驶循环应用于我国摩托车产品上还存在一定缺陷,不能完全按其要求进行试验,需要进行改进.     

体外预应力桥梁关键构造的研究与应用

体外预应力作为预应力体系的重要分支,是当代结构工程建设的流行趋势之一。主要介绍了体外预应力结构的关键部位,包括体外预应力筋和普通钢筋、体外预应力转向块、体外预应力锚固系统等,并指出了体外预应力在工程中的发展前景。     

基于模糊的城市快速路交通流状态判别

“交通状态”具有外延不明确的模糊信息特征,交通流自身特征和评价主体的专业知识都不可忽视。因此,基于快速路检测线圈数据,引入了基于知识的模糊系统来判别快速路交通状态。在充分分析各种交通现象的基础上,提出了交通状态划分原则、依据,评价指标,以及状态判别的模糊集和模糊规则。该方法可以动态的显示路网的交通拥挤范围,为实施交通信息发布以及后期交通瓶颈的判别和改善提供依据。     

Research on vane end face of cam-rotor vane servo motor based on disturbing torque

Cam-rotor vane motor (CRVM) is one of the new continuous hydraulic servo motors with the characteristics of no pulsation of instantaneous flow rate and output torque, small volume and rotating inertia. It is one of the appropriate actuators for hydraulic servo system which has good dynamic and steady-state performance requirements. The ideal output torque of CRVM is pulseless, but the actual output torque of CRVM is pulsating. This is caused by the disturbing torque of contact components, especially the friction between vane and cam-rotor. In order to get better performance of CRVM, which means more stable output torque and smaller disturbing torque, we discuss four kinds of vane end faces (VEFs). Analytic formulae of the normal contact force and the disturbing torque caused by the vane are derived from systematical force analysis. The normal contact force and the disturbing torque vary through a period under different VEF, and the reduced oil pressure is simulated in this paper. The simulation shows that the VEF with the proper round and reduced oil pressure can significantly decrease the disturbing torque and get better servo performance. The experiment results verify the correctness of the theoretical analysis and simulation.     

Simulation-based dynamic adjustments of prices and subsidies for transportation PPP projects based on stakeholders’ satisfaction

Transportation - Public–private partnership (PPP) has been well acknowledged by many as an innovative approach to the procurement of public projects. In their long-term concession periods,...     

惯性制动器在港口起重机大车行走机构的应用

通过对港口起重机大车行走机构的传统制动器与惯性制动器的分析比较,阐述了惯性制动器的优点,以及在不同港口装卸设备上的应用.     

探秘郑和下西洋出发地选择

长江口海运历史绵远,优势独具,这才成为下西洋船队的航海出发地。夏原吉治水,"制淞通娄",娄江口水势骤增,造就了刘家港,而郑和下西洋远航从这里始发也取得了丰厚的收获。