钢管高强混凝土结构的特点和发展

简要论述钢管高强混凝土结构的特点,并对其发展前景进行了展望．     

New rotary valves for pulse-tube refrigerators

In most used rotary valves in GM-type pulse-tube refrigerators the rotor makes heavy mechanical contact with the stator, so the valve is liable to wear, and large torques are needed. In this paper we will describe two types of valves, which have balanced forces on the rotor. In the first valve the rotor and the stator make no mechanical contact. The second type is a contact valve, like the classical valves, but the forces on the rotor are balanced in a different way. Therefore, these valves are less liable to wear, and the torques needed to rotate the valves are small.     

S型波纹管纯弯曲应力和位移的研究

本文引用圆环壳弯曲方程一般解.计算了有实用价值的S型波纹管纯弯曲应力和位移。着重研究了与波纹管设计及应用有关的最主要参数,即最大应力和刚度随S型波纹管初相角变化情况。     

Experimental and numerical crashworthiness investigation of empty and foam-filled end-capped conical tubes

Foam-filled thin-wall structures exhibit significant advantages in light weight and high energy absorption. They have been widely applied in automotive, aerospace, transportation and defense industries. Quasi-static tests were done to investigate the crash behavior of the empty and polyurethane foam-filled end-capped conical tubes. Non-linear dynamic finite element analyses were carried out to simulate the quasi-static tests. The predicted numerical crushing force and fold pattern were found to be in good agreement with the experimental results. The energy absorption capacities of the filled tubes were compared with the empty end-capped conical tubes. The results showed that the energy absorption capability of foam-filled tube is somewhat higher than that of the combined effect of the empty tube and the foam alone. Finally, the crash performance of the empty and foam filled conical and cylindrical tubes were compared. Results from this study can assist aerospace industry to design sounding rocket carrier payload based on foam-filled conical tubes.     

毛细管两相流特性研究进展

毛细管是广泛使用于小制冷装置中的节流元件，主要介绍了毛细管内制冷工质两相流特性的实验研究及理论研究的国内外现状，阐述了目前研究存在的几个问题，探讨了这一领域内研究的几个发展方向。     

一次清洗剂 HEDP 的试验研究

主要探讨ＨＥＤＰ对热力设备的清洗性能,一次清洗钝化效果,为提高化学清洗效率,改善劳动强度,降低清洗成本、缩短清洗周期、减少环境污染开辟新途径。     

方钢管混凝土柱-钢梁外隔板式节点静力和滞回性能分析

采用有限元软件ANSYS对方钢管混凝土柱-钢梁节点进行了非线性静力分析和滞回分析,讨论外隔板式节点翼缘斜率对节点的应力分布规律、承载力、延性和滞回性能的影响.分析表明,外隔板式节点具有很好的刚度和延性,节点滞回环饱满,耗能能力强,当梁端翼缘斜率不小于1/4时,可获得更好的受力性能.梁柱连接处柱脚附近应力集中现象严重,因此梁柱连接的焊缝质量要有充分保证.     

大滞后系统的分层递阶智能控制研究

盘管出水口温度控制系统和许多化工热工过程温度控制一样，具有大滞后和非线性的特点，根据被控对象的不同情况，分别采用专家控制、模糊控制、神经网络PID控制，提出了一套基于分层递阶智能控制方案，并且通过实验取得了较好的控制效果。     

交流阻抗法在凝汽器黄铜管腐蚀研究中的应用

探讨交流阻抗法研究凝汽器黄铜管在循环冷却水系统中的腐蚀问题.采用热电厂实际使用的黄铜管制作管状传感器,利用交流阻抗法在同种材料三电极体系电解池中测量传感器的电化学阻抗谱,并与经典三电极体系电解池下的数值作比较.结果表明,实验室数据与现场测试数据基本吻合,交流阻抗法可以提供凝汽器黄铜管在循环冷却水系统中的年腐蚀速率和极化电阻,帮助现场工作人员及时了解凝汽器黄铜管的腐蚀状况.交流阻抗法可以有效地评定黄铜管的耐腐蚀性能,为现场腐蚀监测,进而指导生产提供了有益信息.     

A NONDESTRUCTIVE METHOD TO MEASURE RESIDUAL ADSORPTION CAPACITY OF CHARCOAL FILTERS

High surface area charcoal bed filters have been used for over a half a century to adsorb undesirable vapors from gas streams. One problem encountered when using these niter beds is that there is presently no simple, reliable, nondestructive method to measure their Residual Adsorption Capacity, RAC. This is particularly critical in situations where harmful vapors are being adsorbed.

An investigation has been underway to use pulses of weakly adsorbed gases such as ethane and/or methane to measure RAC. The hypothesis being that these weakly adsorbed gases will “count” unoccupied adsorption sites. In the present study, dimethyl methylphosphonate (DMMP) was used to “irreversibly” occupy available siles to various extents on different niters. The Reduced Retention Time. θ, (the ratio of the adjusted retention time to the space time) and the Resolution (R) between peaks of methane and ethane were found to correlate to RAC under dry and wet (humid) conditions.