左江水利枢纽工程施工导流设计的优化

导流工程在施工条件改变时,应根据工程的实际情况进行相应的调整及优化,以达到节省导流工程投资、满足主体工程施工要求的目的;介绍了左江水利枢纽工程施工导流设计的优化情况。     

弹性心轴的设计

介绍了适合加工衬套类零件的3种弹性心轴的设计原理及应用场所。采用了精度较高的弹性心轴作为工装夹具,能够保证衬套类零件内、外圆精加工后的同轴度精度达到很高要求。     

浅谈水闸安全检测

通过对华东沿海地区80年代以前修建的一些在役水闸工程的系统安全检测和分析,发现了水闸工程存在的安全隐患,同时也了解水闸工程尚有的潜在能力。提醒水闸管理部门,在役水闸满足目前社会发展需要的同时,还必须高度重视水闸的安全生产运行和管理。水闸安全检测就是利用先进的检测手段,为业主及时、高效、经济和高质量地解决水闸工程存在的实际问题。     

反腐败之"高薪养廉"对策辨误

“高薪养廉”是很多人极力推崇的对策之一，无论是从理论上还是实践上看，“高薪养廉”都不适合中国国情，不能从根本上解决腐败问题。腐败问题的解决是一项系统工程。     

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.     

碾压混凝土坝施工进度与质量控制的新措施

碾压混凝土重力坝和拱坝由于连续施工的坝体混凝土体积大，施工期间需要采取较为严格的温度控制措施，而所采取的温控措施是否有效，目前尚没有一个能够用于实际施工过程的快速有效的评估方法和方式，不能根据已施工坝体内的实际情况来控制施工进度和质量。利用分布式光纤温度测量系统来快速地获得坝体混凝土内部的大量温度信息，进而实际标定温度仿真程序并通过标定过程模拟拟施工的连续碾压层，以检验其温控措施的有效性。通过坝体内部的温度、温度变化速率和梯度来达到实时控制坝体碾压上升速度、坝面和仓面养护、以及冷缝灌浆处理等目的。     

A BOUNDARY INTEGRAL EQUATION AND ITS NUMERICAL SOLUTION OF POTENTIAL FLOW AROUND SURFACE-IRREGULA-RITIES

In this paper,using complex functional theory,the authors turn the potentialflow around the surface irregularities in a pressure conduit and semi-infinite platforms intoDirichlet problem.Based on Schwarz formula and by the application of Plemelj's formula,theauthors change the problem into the integration of a Cauchy boundary integral equation in theflow plane through the substitution of variables.Using numerical integration,the authors obtainthe velocity distribution and pressure coefficient along surface irregularities and platforms.Thephysical concept of this method is clear,the convergent speed is rapid and the computative effi-ciency is high.The calculated values agree well with the measured results.It is an effective andsimple method in solving potential flow.     

Firm-level interactions between exporting and productivity: Industry-specific evidence

This paper investigates interactions between exporting and productivity at the firm level, using a panel of firms in the UK chemical industry. This is both highly technology intensive and the UK’s largest exporting sector. We find exporters are more productive than non-exporters, but are also on average smaller. This superior productivity performance among exporters appears to be caused by both self-selection and learning-by-exporting effects. In contrast to other studies, we find learning effects are significantly positive among new entrants, weaker for more experienced exporters and negative for established exporters. JEL no. F14, D21, L65