A prediction method for thermal conductivity of alternative refrigerants in the liquid phase

A prediction method for the thermal conductivity of halocarbon refrigerants in the saturated liquid state in the reduced temperature range 0.3 to well above 0.9 is presented in this paper. The aim of the method is to present a very simple calculation of the transport property useful for engineering purposes. The method determines thermal conductivity as a sole function of the reduced temperature and requires the knowledge of a parameter dependent upon easily available physical constants characteristic of each compound. The method is validated against experimental data available in the literature, giving average absolute deviations which are usually less than 5%, with maximum absolute deviations generally less than 10%. An extension of the method to estimate thermal conductivity of binary mixtures is also presented, along with a comparison with the few experimental data available in the literature.Paper presented at the Twelfth Symposium on Thermophysical Properties, June 19–24, 1994, Boulder, Colorado, U.S.A.     

Dynamic elastic-plastic behaviour of whipping pipes: experiments and theoretical model

This paper is concerned with the problem of pipe whip, the dynamic response of a high pressure piping system subjected to an end force as the result of a pipe break which releases a jet of fluid from the broken section. Both experimental and theoretical results are presented concerning the dynamic elastic-plastic behaviour of cantilever pipes subjected to a transverse force pulse at the free end. Comparisons between experimental data and theoretical predictions are made for mild-steel pipes with outer diameter-to-thickness ratios of 19.5, 28 and 32. It is demonstrated that, for these geometries, the whipping pipes display three characteristically different responses, viz. elastic, plastic hardening behaviour for thick pipes, elastic, plastic hardening-softening behaviour for moderately thick pipes and elastic, plastic hardening-softening-collapse behaviour for thinner pipes. The experimental data taken from a series of high-speed films are compared with the predictions of the instantaneous shapes of the whipping pipes derived from both a rigid, perfectly-plastic, large deflection, dynamic beam model and a more comprehensive model which incorporates the effects of elasticity and plastic hardening and softening, the details of which are presented in the paper.     

间断Galerkin方法的最优误差限

本文考虑了数性双曲方程的离散Ｇａｌｅｒｋｉｎ方法。如果精确到光滑的并且同是几乎均匀的，证明了对于分层常数元的最优的和超收敛的误差限。     

Intelligent Control of Consolidation and Solidification Processes

Intelligent processing of materials (IPM) deals with the integration of process models and in situ sensors into an intelligent process controller to achieve desired material properties. IPM-based control systems recently have been developed for both consolidation and solidification processes. This article explores the application of models based on the finite- element method (FEM) to develop process actuation systems, to design process schedules and component shape, and to develop a control model with which to control the process. The results in this article were presented at the AeroMat ’93 Advanced Aerospace Materials/Processes Conference and Exposition, Anaheim, CA, 7–10 June 1993     

柔性机械手系统的动力学方程

本文应用动力学普遍方程,导出了单链柔性机械手系统的动力学方程;并以递推形式分析该方程的求解过程,递推的每一步只须解低维的方程组,因而便于计算.还讨论了多链柔性树状系统动力学方程的求解方案,它与单链柔性机械手系统具有相似性,便于编制程序.     

天然调味料──酵母抽提物的研究进展

着重论述了酵母抽提物的特性、在食品中的应用前景、制造方法、工业化生产中存在的问题及其解决方法，并对酵母抽提物的发展方向作一展望。     

压力传感器的应力计算

从弹性力学的板壳理论出发,对不同参数的凸型板结构形变膜受压后的应力分布作了近似计算,为高线性度SOI压力传感器的芯片设计提供了理论指导。用BESOI技术研制的凸型板结构集成压力传感器的非线性度达0 09%,样品灵敏度的实测值与应力计算理论值的差别约17%。     

紧凑式换热面瞬态实验中的全程直接配比法

在紧凑式换热面的瞬态实验中，为获得准确的实验结果，不仅要建立符合试验工况的理 论解，而且还要选择合适的配比方法，以便尽可能减小测量误差对配比结果的影响．本文就瞬态实 验的配比，提出了一种新的基于计算机的全程直接配比法，由于它采用了所有可用测试点进行配 比并且其理论解与实测值的配比误差是通过最小搜索步长来控制的，因此，实验结果的准确性和 可靠性优于通常应用的间接配比法和选点配比法．     

羊皮服装革的弯曲应力松弛性能及其与(手感)弹性之关系研究

本文研究了羊皮服装革的弯曲应力衰减性能。对应力衰减常数（αｂ）及其与羊皮服装革手感弹性的关系进行了讨论。结果表明：αｂ与革的手感弹性相关。αｂ值定量反映出革的手感弹性优劣。     

武钢 3×10~4m~3/h 空分手动变负荷生产的探索与实践

对武钢引进的两台３×１０４ｍ３／ｈ空分设备，为改变其自动变负荷生产调节范围小、时间长的问题，采用了人工手动变负荷的操作方法。实践表明：扩大了增减产范围，缩短了调节时间，有十分明显的综合经济效益，可供大型空分变负荷生产借鉴参考。