A METHOD FOR CHARACTERIZING DUST DEFLAGRATION BEHAVIOR FOR APPLICATION TO VENT RELIEF DESIGN

ABSTRACT

The best available design data for vent relief of dust deflagrations are contained in the nomagraphs presented by NFPA and VDI. In order to utilize these data, experimental measurements must be made to characterize the dust in the enclosure to be protected. In the absence of a single standard test for such measurements, various test vessels of 20 liters or greater volume are in use following the demonstration that the 1.2 liter Hartmann apparatus yields data which are incompatible with the nomograph method. A 26-liter test facility is described and the effect of test variables detailed, showing how these test variables may be standardized. The overall philosophy of vent relief design is outlined and it is shown that various approximations exist at every stage of the design process, which is a compromise rather than a “worst case” solution.     

一种可表征冷却收缩应力对聚合物结晶影响的动力学方法

从Avrami等关于结晶相转变的严格微分公式和准静态假设条件出发,导得了一种可表征体系冷却收缩应力对聚合物结晶影响的动力学处理方法,采用该方法对PP及3种不同分子量的HDPE的研究结果表明,聚合物熔体冷却过程中的收缩应力有促进结晶的作用。可引起体系晶体生长指数n,生长速率常数k和结晶度的显著增大,试样k值随冷速率α的变化率（Δk/Δα)与其材料缺口冲击强度值之间有着良好的对应关系。     

支撑与梁柱板式连接节点低周疲劳分析及设计方法研究

为实现强节点、弱构件的抗震设计思想,保证支撑与梁柱采用板式连接时节点板的低周疲劳寿命高于被连接的支撑构件,使用ANSYS程序对支撑及节点板进行了大量有限元参数分析,研究了支撑轴线与柱夹角、节点板距支撑轴线最近的嵌固点向支撑轴线所做垂线与支撑端部的距离、节点板厚度、支撑长细比、工字形截面支撑翼缘宽厚比等参数对支撑系统(支撑和节点板)低周疲劳寿命的影响规律。提出了基于工字形截面支撑长细比和翼缘宽厚比不同取值情况下节点板支撑端部净距的确定方法,为节点板的抗震设计提供了依据。     

改良BBS法评价聚氨酯发泡催化剂

改良BBs法用光电法测发泡高度-时间曲线,用机械手完成投掷钢球动作,过程用微机控制。本文对此法测得的三乙胺、四甲基乙二胺、二甲基乙醇胺、双(二甲基氨基乙基)醚、三乙烯二胺等催化剂在聚氨酯软质泡沫塑料形成过程中的胶化-发泡曲线进行了讨论,并评价了它们的催化特性。改良BBs法与手工BBs法相比,具有检测精度高,样本采集点多的优点。     

蒙特卡洛法在HIRFL-CSR钛升华泵设计中的应用

介绍了用蒙特卡洛法计算HIRFL-CSR钛升华泵对于不同气体吸附系数在分子流条件下的吸附概率,并分析了挡板的形状、位置设置对于吸附概率的影响.通过实验测试,发现HIRFL-CSR钛升华泵对H2的抽速与计算值接近,证明用蒙特卡洛法模拟计算、设计钛升华泵是可行的.     

A TWO-LEVEL DECOMPOSITION METHOD FOR DESIGN OPTIMIZATION

In this paper, a two-level decomposition method for design optimization is proposed which is an extension of the model coordination methods. The method couples the global monotonicity analysis of the first-level subproblem(s) with an optimization method (single-level method) or the second-level problem. Three classes of problems are considered where in the first-level they have: (1) one subproblem with one local variable, (2) several subproblems with one local variable, and (3) several subproblems with several local variables. Some test results have been presented which shows the improved performance of the proposed approach over a conventional single-level optimization method.     

基于特征的模具参数化设计方法

基于模具的特点，对模具特征的信息构成进行了研究。采用模具的装配特征和零件特征表达模具的装配关系和结构，采用层次结构表达特征信息，在参数化设计时，采用形状尺寸和结构尺寸驱动方式修改特征的形状和定位。该方法可方便模具的结构描述和参数化设计，有利于实现模具ＣＡＤ／ＣＡＭ系统的集成。     

钢筋混凝土框架结构抗连续倒塌设计方法的研究

首先简要介绍了国外抗连续倒塌设计规范的主要设计方法和分类设计体系,然后重点对钢筋混凝土框架结构抗连续倒塌拆除构件设计法和拉结强度设计法进行较为深入的分析研究。在基于非线性动力分析的拆除构件设计法进行分析的基础上,对基于线弹性静力分析的拆除构件法的原理和设计参数进行了分析和验算,提出适合我国工程结构的设计参数。分析了国外规范拉结强度设计法应用于按我国规范设计的框架结构的不适用性及其原因,并对国外规范拉结强度设计法中基本拉结强度的计算模型所存在的不足进行了改进,提出了考虑空间传力路径等因素的拉结强度设计法。通过算例对该文建议的线弹性静力拆除构件设计法和拉结强度设计法进行了设计验证。     

DESIGN AND GROWTH RULES FOR BIOLOGICAL STRUCTURES AND THEIR APPLICATION TO ENGINEERING

Starting from the well-accepted but not proved hypothesis that biological load carrying structures are highly optimized by growth, some examples are given and their degrees of optimization are demonstrated. Especially branch joints, deer antlers, branch holes in trees and modelling growth of trees loaded by contact stresses are discussed. On the basis of the knowledge that biological structures always try to avoid localized stress peaks (notch stresses), and that they try to grow into a locally homogeneous surface stress state, a new method of CAO (computer aided shape-optimization) is proposed which relies on biological growth. Its efficiency and success are demonstrated for two- and three-dimensional structures with very homogenous stress states after optimization.     

一种微波吸收涂层的计算机辅助设计新方法

本文提出一种应用模式的识别优化技术的微波吸收材料多层涂层的计算机辅助设计新方法，避免了常规方法由于变量过多而常常陷入局部最小，从而获得多层涂层的优化设计方案本文还分析了多层涂层扩展频宽和吸收锋的关系，讨论了最佳设计中对表面层和近金属层的材料电磁参数的要求。     

STRATEGY FOR CHARACTERIZING FRACTURE TOUGHNESS IN THE DUCTILE TO BRITTLE TRANSITION REGIME

Abstract— A tentative method is proposed for treating the scatter and size effects of fracture toughness of ferratic steels in the ductile-to-brittle transition regime. The method is aimed at the determination of the probability function for initiation of fast growing cleavage cracks under the plane strain condition. The practical relevance of this method has been checked with toughness data sets obtained from various CT-specimen sizes and CCT-specimens of a pressure vessel steel tested at two different temperatures in the transition regime.     

APPLICATION OF GRIDS TO PLASTICS FOR THE MOIRE FRINGE METHOD OF STRAIN MEASUREMENT

There has been considerable interest during recent years on the measurement of strain using the moiré fringe method. This report reviews the techniques of applying grids to specimens and gives details of methods used at NEL. Strain measurements on a simple tensile test specimen using the moiré mismatch technique are compared with those obtained with a Linley extenso-meter.     

AN OPTIMIZATION METHOD TO DESIGN HYDRAULIC NETWORKS

Nonlinear programming is applied to the solution of hydraulic network problems. The significant differences between the proposed optimization method and other conventional methods are that this method can solve problems with mixed unknowns (e.g. pipe sizes, discharges and pressures), it can optimize solutions involving unknowns defined by inequalities (e.g. specifled minimum discharge and pressure values), it can handle network control problems such as required valve adjustments or in-line booster pump needs, and it may solve problems of networks with continuous discharge distribution along the pipes.     

橡胶悬置元件结构参数优化设计方法

由于橡胶悬置元件的结构比较复杂,截面不规则,无法用传统的优化方法对其结构优化.利用遗传算法和神经网络相结合的策略对橡胶悬置元件的几何结构参数进行优化,即用神经网络学习算法建立橡胶悬置元件几何结构参数与其三个方向刚度的非线性全局映射关系,获得遗传算法求解结构优化问题所需的目标函数,用遗传算法进行优胜劣汰的寻优搜索运算,求出最优解.优化结果表明,橡胶悬置元件结构参数优化设计方法是可行的.     

A SEGMENTAL METHOD FOR THE DISCRETE OPTIMUM DESIGN OF STRUCTURES

A simple method based upon linear programming is described for the design of minimum weight structures under the restrictions that member sizes and/or material properties may be chosen only from discrete sets. The types of structures considered are those composed of axial force bars, membrane plates and shear panels. The method avoids the combinatorial nature of discrete optimization by introducing the concept of segmental members. The segmental optimum design is found by linear programming. Its weight is a lower bound to the weight of the discrete optimum design. A simple method for achieving a discrete optimum design from a segmental optimum design is described. Several examples of discrete optimum truss designs are presented.     

大爆破电力起爆网路的快速设计

在工程爆破设计中，为确保大爆破安全、可靠的起爆，本文对起爆电源一定条件下，大爆破电力复式并串联起爆网路的支路数目确定提出了一种优化方法。     

浅析居民环境行为影响因素在城市设计的应用研究

近年来,随着经济的飞速发展,环境问题也成为热门话题。基于对影响居民环境行为的重要因素的分析,本文对城市居民的环境意识与环境行为进行了关联与研究,同时通过对城市中现有的环保设计进行分析,为提升城市居民环保意识、改善城市环境生态提出了可行性建议。     

六层非对称框架结构大楼控制爆破拆除

根据爆破楼体为非对称框架结构的力学特征和作业空间狭窄、周围环境极其复杂、安全要求高的特点,应用控制爆破理论和技术,对位于盘锦市闹市区长２０．５ｍ、宽１７．５ｍ、高２４ｍ的六层浇筑框架结构的紫澜门大楼成功地进行了定向爆破。在本次爆破中,我们对爆破方案进行了系统的技术论证和爆破参数深化计算,并在爆破施工中采取了有效的安全防护措施和爆破地震效应观测,取得了理想的爆破效果,为今后类似工程提供了技术依据。     

A HIGHER ORDER EXPANSION METHOD FOR OPTIMUM DESIGN OF STRUCTURES FOR SPECIFIED FUNDAMENTAL EIGENVALUE

A higher order expansion method is presented for optimum design of structures for specified fundamental eigenvalue. The design function, fundamental eigenmode and total volume are expressed in terms of the Taylor series expansion with respect to the specified fundamental eigenvalue. A solution with null design function, where all the eigenvalues degenerate to null, is chosen as a trivial initial solution, and higher order terms are incorporated. By using the proposed method, a set of optimum designs for a wide range of fundamental eigenvalues is easily found. The proposed method is applied to an Euler-Bernoulli beam and expanded forms are presented analytically for a simply supported beam. The method is then extended to a plane truss, and the results are compared with those by an optimality criteria method.     

确定铝合金P—S—N曲线的一种简便方法

根据作者提出的应力疲劳公式，建立了确定铝合金Ｐ－Ｓ－Ｎ曲线的简便方法，如果循环应力下材料的疲劳发布已知，且与高循环应力相比，试件在低循环应力下个有更长的疲劳寿命和更同的寿命分散度，则有可能用本文的方法确定材料的疲劳强度分布和Ｐ－Ｓ－Ｎ曲线表达式。