连轧管机组液压系统管路冲洗方法浅析

通过对液压管路冲洗实质的分析,指出正确选择雷诺数的方法,以此为基础计算冲洗泵站所需的压力和流量,并应用于某连轧管机液压管路冲洗过程中。现场实践表明所设计方法正确,能够缩短冲洗时间,提高冲洗效率。     

锅炉管内壁氧化皮厚度测量影响因素分析

本文针对锅炉管内壁氧化皮厚度的超声波测量，研究了超声波在氧化皮中的传播速度、氧化皮分层、剥落、氧化皮与金属基体间隙等因素对测量准确性的影响规律，同时给出了典型情况下的测量波形。研究结果对氧化皮厚度超声波测量仪器的使用，提高测量准确性具有指导及参考意义。     

An environmental and thermodynamic analysis to select R22 alternative working fluids

R22, a hydrochlorofluorocarbon (HCFC), is used widely in the air-conditioning and refrigeration industry; however, it is being phased out along with other HCFCs, due to concerns about its impact on ozone depletion. In the EEC countries its production, commercialization and use will be forbidden before the end of 1999.

According to the AREP (R22 Alternative Refrigerants Evaluation Program) project, coordinated by the Air-conditioning and Refrigeration Institute (ARI) a group of substances has been pointed out as potential ozone-free R22 alternatives.

In this paper some working fluids, among those one considered by AREP, will be evaluated by means of a comparative thermodynamic analysis. Furthermore, particular interest will be paid to the environmental global impact joined to the substitution. To this aim, the Total Equivalent Warming Impact (TEWI) will be used as a tool to evaluate both direct and indirect contributions to the “greenhouse effect” linked to an operating vapour compression plant.     

On quasi-static crushing of thin-walled steel structures in cold temperature: Experimental and numerical studies

The aim of the study reported herein was to investigate the effects of low temperatures on the crushing characteristics of steel plated structures. The motivation of this study is for the analysis of ship collisions in Arctic waters. A series of tensile coupon tests were performed to examine their material behaviour at low temperatures, and then quasi-static axial crushing tests were carried out on thin-walled square tubes. The test tubes were made of ASTM A500-type carbon steel, and both the tensile coupon tests of the material and the crushing tests of the tubes were performed in a liquid nitrogen cooled chamber. To reflect the conditions of the Arctic environment more realistically, the tensile coupon tests of the material were also carried out in a dry-ice cooled chamber. LS-DYNA nonlinear finite element method simulations applying a practical approach of modelling techniques were performed to investigate the structural crashworthiness of the thin-walled steel tubes numerically. The tests in the liquid nitrogen cooled chamber showed that the fracture strain of the material was not affected (reduced) by temperatures as low as −80 °C, although fracture strain was significantly reduced below −100 °C. The fracture strain results obtained in the dry-ice cooled chamber, however, show this strain to be affected (reduced) by low temperatures even between 0 °C and −80 °C, which is equivalent to the Arctic environment. It was also observed that fracture occurs in thin-walled tubes under crushing loads at low temperatures. The LS-DYNA computations also detected the fracture behaviour of test tubes in cold temperatures in a relevant way.     

压水堆核电厂蒸汽发生器传热管的降质问题

核电厂蒸汽发生器传热管的降质将影响到核电厂一回路边界的完整性。通过对蒸汽发生器传热管的降质模式进行分析，并对在役传热管无损检测技术应用以及寿命预测的介绍，从而针对产生的传热管降质的原因，采取相应的防护措施，确保蒸汽发生器传热管的安全运行。     

预应力混凝土管桩两种施工方法的特点比较

预应力管桩有捶击沉桩和静压沉桩两种施工方法,其各自存在优缺点及适应性,对结构设计师和土建建造师正确了解其特性和正确选用施工方法具有重要意义。     

磨料微粉粒度检测与数据处理系统设计

针对目前沉降管测定微粉粒度普遍存在数据记录和处理过程中人为因素较大,影响测试结果的准确性等问题,利用斯托克丝定律和新一代微处理器的特点,设计了磨料微粉粒度检测与数据处理系统。论文介绍了沉降法基本原理和计算数学模型、沉降液的密度和黏度与温度修正关系,给出了系统软硬件电路。通过对相关样品进行实际测量和数据处理分析,结果表明:数据记录和处理稳定、操作方便、曲线显示美观,易于扩展等特点,具有广泛的应用前景。     

矿用聚乙烯(PE)管材的性能特点

为了满足煤矿安全生产的需要,必须对矿井瓦斯进行抽放。传统抽放管路都是使用钢管,其重量大、安全性差、不易安装。矿用聚乙烯管材具有重量轻、防静电、阻燃、碰撞不起火花、耐腐蚀、耐磨损、易于安装等特点,使用寿命可达到50 a,代表着煤矿瓦斯抽放管道的发展趋势。     

2010年俄罗斯钢管工业的发展情况

2010年国际金融危机的影响逐渐减弱,在俄罗斯政府的一系列扶持政策措施的作用下,俄罗斯钢管工业得到了良性发展,出现了大幅增长.介绍了俄罗斯几大钢管生产企业--俄罗斯钢管冶金公司、俄罗斯联合冶金公司、俄罗斯车里雅宾斯克钢管公司和俄罗斯北方钢铁集团伊若尔斯克钢管厂2010年的生产经营情况.     

Integration of superconducting magnets with cryogen-free dilution refrigerator systems

There has been much recent research interest into “cryogen-free” dilution refrigerators. Cryogen-free systems have some advantages from a safety and convenience point of view as liquid cryogens are unnecessary. However, this also makes integrating the low-temperature system with a high magnetic field environment much more challenging. Here we shall describe recent successes of integrating superconducting magnets and dilution refrigerators into one system requiring a single pulse tube cooler. The resulting environment provides experimental temperatures between 7 mK and 30 K and magnetic fields up to 12 T. We shall describe the effects of AC loss heating in such systems on the pulse tube refrigerator when the field is ramped and also the effects of eddy current heating on the mixing chamber in sweeping fields.