Non-Uniform Sediment Transport Downstream from Reservoir     

李义天  陈飞 《天津大学学报(英文版)》2008,14(4):263-270

The transport characters of non-uniform sediment before and after the reservoir operation are compared and analyzed. Field data from the Three Gorges Reservoir (TGR), Danjiangkou, and Sanmenxia reservoir indicate that the transport character of coarse particle is various in different reaches. Before the reservoir operation, the dramatic decrease of the hydraulic condition in some reaches is the main reason to cause the coarse particle deposited. After the reservoir operation, almost all grain sized sediment may be eroded, when the reach is eroded seriously. However, the transport character of the coarse particle will be consistent with what it was before, when the reach is not eroded seriously. The deposition amount will be less than its pre-dam value, and it will tend to decrease with the time going on. Erosion of fine particle results from its unsaturation. Long-distance erosion downstream from reservoir is caused by shortage of the supply from riverbed, especially the shortage of fine particle. Supported by the National Basic Research Program of China(“973” Program, No.2003CB415200). LI Yitian, born in 1957, male, Prof.  相似文献   

输变电工程地导线压接用液压机的自制化的思考     

潘素坚 《中国科技信息》2006,(23):63-64

针对输变电工程地导线压接用液压机在多年使用后出现的各种弊端,经过反复的试制,通过简化泵站以及对溢流阀位置做相应调整等措施,不仅使得液压机自制化,还降低了设备的购置成本。  相似文献   

Credibility and Security of Weighing System for Large Structure Object     

章青  周延兴 《天津大学学报(英文版)》2006,12(2):92-95

The weighing system designed for large structure object is mainly composed of three parts. The part of hydraulic system is made up of hydraulic cylinders, high pressure hydraulic hoses and electric pumps; the part of computer controlling system comprises pressure sensors, displacement sensors, data acquisitions, RS 485 network and the computer controlling model; the part of loading system is composed of the fulcrum structure and the concrete girder. The measurement principle and composition of the weighing system are discussed in this paper. Credibility and security of the weighing system are fully considered during the design phase. The hydraulic system is controlled by pilot operated check valves in case of the sudden loss of system pressure. The states of all gauges and RS485 network are monitored by computer controlling system functioning in different modules. When the system is running incorrectly, it will be switched to manual mode and give alarm. The finite element method is employed to analyze fulcrum structure so that the system has enough intensity to be lifted. Hence the reliability of the whole system is enhanced.  相似文献   

基于S7-1200PLC的金属打包机控制系统研究          下载免费PDF全文

张淑灏  曹胜敏 《唐山学院学报》2019,32(6):31-33,62

利用S7-1200PLC和MCGS触摸屏实现了对液压金属打包机的全自动控制,其中设计了打包环节的部分控制程序,将传送带送料替代人工送料,改翻包出包为前门推包出包。仿真实验表明,系统稳定可靠,安全性和生产效率较高。  相似文献   

40t燃油铝混合炉门升降机构的改造     

崔文平  侯纯军 《焦作大学学报》2005,19(2):63-64

介绍了40t燃油铝混合炉炉门提升机构改造前存在的问题及改造过程。并对炉门提升机构液压控制原理、液压站布置、液压缸的改造方法进行了详细说明。  相似文献   

浅谈单向阀在液压系统中的应用     

廖广平 《鄂州大学学报》2005,12(3):67-69

单向阀结构简单，性能稳定，被广泛地用于液压系统中，起着其他控制阀不可替代的作用。单向阀还可与其他控制阀组成复合阀，也被广泛地用于液压系统中。  相似文献   

对原175型柴油机机体三面镗组合机床液压系统的改进     

许吉云 《衡阳师范学院学报》1995,(6)

本文介绍采用单电机双联泵控制多油缸动作如何进行防干扰问题，采用立体建模使液压站板块内部结构简单，直观性强，绘制生产图纸容易。改进后的组机节能、高效、维修方便。  相似文献   

液压系统故障诊断方法分析     

方坤  孙翠美  赵强 《鸡西大学学报》2001,(4)

分析了液压系统故障诊断的方法,并结合实例进行分析,对从事液压技术的人员有很好的参考作用.  相似文献   

工程机械液压系统污染分析与控制     

姚永平 《宜春学院学报》2006,28(4):64-65

分析了工程机械液压系统中污染物的来源、污染的危害以及油液中污染物含量的测定方法,提出了控制污染的一些具体措施.  相似文献   

坐标镗床液压系统中的爬行原因及对策     

颜斌 《福建工程学院学报》2004,2(4):413-415

通过时机床液压系统中的工作台产生爬行的机理的分析，认为，系统驱动刚性差、摩擦阻力变化、液压元件间隙大、液压油污染是坐标镗床液压系统中的工作台在以极低的速度移动时产生爬行的主要原因，并针时各具体原因，提出相应时策，以排除爬行。  相似文献