北京火车站抗震鉴定与加固技术

北京火车站是首都重要的标志性建筑之一 ,195 9年建成 ,当时按 7度设防考虑 ,存在着许多不符合抗震要求的问题 ,一些设施也明显不能满足现代使用功能要求。北京火车站抗震加固与改造设计项目组 ,运用多种先进的加固手段 ,在保持原建筑外貌不变的前提下 ,实现了抗震能力和改善使用功能的协调 ,取得了大型公共建筑加固改造的新经验     

水轮机运行经历的重大问题(美国陆军工程师团的经验)

美国陆军工程师团经管运行的有344台水轮机,有些水轮机运行已超过50年。某些机组曾经历过重大的运行问题。为获得满意的解决,在工程师团成员、设计者、制造者和运行人员之间的有效合作是必需的。美国陆军工程师团已建成的水力发电设施遍布全美国,现在仍有70％在运行。其规模可从弗吉尼亚州罗诺克河上的14MW费尔波特水电站起,到位于华盛顿州和俄勒冈州哥伦比亚河上的2200     

SIMILARITY LAW OF FLUCTUATING PRESSURE WITHIN HYDRAULIC JUMP AREA

Through a series of model tests of five scales for 2-D free hydraulic jump, the da-ta of fluctuating pressure acting on the floor level within the hydraulic jump were obtained. Dur-ing the experiments, Froude number varied from 2.94 to 8.61, and Reynolds number rangedfrom 2×10~4 to 6×10~5. Experiment results indicate that the amplitude scale of fluctuating pres-sure is the length scale of model, i. e. P'=L, which agrees with gravity similarity law: Thefrequency scale of the fluctuating pressure is a unity i. e., f=1, which does not satisfy thegravity similarity law.     

THE FLOW PRODUCED IN PARTICLE-SUSPENSION BY AN INFINITE ROTATING DISK:SERIES SOLUTION

To the flow produced in particle-suspension by a rotating disk of infinite extent,the asymptotic behavior at infinity is analyzed.A corresponding series solution is presented.It isshown that this approach yields widely valid solutions of high accuracy for all the cases in whichthat suction or weak injection at the disk surface exists.For the cases that strong injection or par-ticle-free band exists,the series method fails.     

TURBULENCE MEASUREMENT INSTRUMENT WITH A SILICON PIEZORE-SISTANCE BEAM

A newly developed turbulence measurement instrument is introduced in the paper.The transducer of the device is based on the principle of the effect of silicon piezoresistance that isintegrated in a Wheatstone bridge on a pure silicon beam. At one end of the beam, a small lightball is installed as the target forced by the water flow. The other parts are prevented from thewater flow with a sophisticated stainless steel tube. The instrument can be used to measure turbu-lent velocities either in clear Water or in flows bearing hyperconcentration of sediment. It can al-so be used to measure velocities in both glass flume and model experiments as well as in pipe ex-periment by being mounted in a special way.     

提高动力问题直接积分法的精度

一、概述在结构动力分析中,广泛采用直接积分法求解时域内的运动方程。主要的方法分两类。第一类为显式方法。即将加速度和速度用连续的位移值表示,在运动方程中,加速度和速度被每一时间步长内所要求出的位移矢量所代替。这类方法的主要区别在于有各种不同的假定,它们的—个主要缺陷就是它们是条件稳定的。事实上可以说明所选时间步长增量必须远     

稀释剂和载体

为了使农药的浓度降低到仅对靶标具有一定的毒性水平,需将其用惰性物质进行稀释,根据用途与需要加工成粉剂、可湿性粉剂、颗粒剂、乳油和悬浮剂等各种“农药制剂”。其中,在世界所有农药制剂产品中,粉剂和水分散性粉剂占有主要地位。为了制取这些制剂,往往用粘土及相关的水合硅铝酸盐矿物质为载体和稀释剂。这些矿物除了能降低农药浓度外,还可赋予农药一定的悬浮性和密度等。由于它们具有吸附能力,由此可使农药包含于它     

灰色系统理论用于塔板的评价与选择

本文根据灰色系统理论,提出了一种用于塔板评价与选择的关联分析法。经对实例的分析评判,得出了相应的结果,可供设计和生产部门参考。     

测量生产井含水率的一种新方法：—屏蔽式感应法

提出了利用屏蔽式感应线圈测量生产井中油水混合物的混合电导率进而推断含水率的方案,并用几何因子理论对仪器设计参数范围进行了估算。结果表明,使用1～5MHz的工作频率,二次场感应信号可达到μV数量级。从原理上看,该方案能测量高含水率的油水混合物,并且不受金属套管的影响。