大型油池火灾实验研究进展

文章回顾了日本近年来大型油池火灾的实验研究结果。进行大型火灾实验需要巨大的投资和大型敞开空间 ,但进行大型实验对于获得真实大型油罐火灾数据是很重要的。     

发电厂大型电动机检修及故障处理

发电厂大型电动机的安全正常运行是电力生产正常运行的重要环节,从大型电动机常见故障、电动机故障处理方法以及大型电动机检修方案和步骤三方面阐述了大型电动机运行故障检修的主要内容,简单总结了大型电动机常见故障,提出了电动机故障处理的一般步骤和方法,分析了大型电动机运行检修的主要内容,分析结果可以为大型电动机的检修提供参考。     

浅谈城市发展背景下的大型体育建筑可持续利用

赛事导向的大型体育建筑建设成为城市发展的重要触媒．同时．城市发展带来大型体育建筑的区位、交通、环境以及功能需求的变化．在城市发展背景下．大型体育建筑如何实现可持续利用值得探讨。本文分析城市发展对大型体育建筑发展的影响．研究城市发展背景下的大型体育建筑功能演变．探析大型体育建筑可持续利用方向．在此基础上提出适应城市发展的大型体育建筑设计策略。     

关于加强大型石油化工火灾消防通信的几点建议

通过对大型石油化工火灾的危害性进行分析,指出大型石油化工火灾消防通信的重要性,对大型石油化工火灾由于受地理位置、火灾现场环境等因素限制消防通信存在的问题进行分析,提出加强大型石油化工火灾消防通信的建议,以确保大型石油化工火灾消防通信畅通。     

基于SEM的大型工程项目质量管理因素指标体系研究

随着我国经济的快速发展,国家对大型工程建设的投资力度越来越大,大型工程建设对我国的国民经济发挥着不可替代的作用,因此对大型工程建设的管理不可忽视。虽然总体上我国大型工程质量有了显著提高,但仍存在一些问题。而且大型工程事业关系着我们每个人的生活和国家的经济发展,其质量又是大型工程的生命线,所以大型工程质量问题是一个具有重要研究意义的课题。本文首先介绍了结构方程模型相对传统分析方法的优势,接着运用结构方程模型（SEM）对大型工程质量的影响因素进行了具体分析,估计出其简单路径图,最后得出了大型工程质量管理的结构方程模型及其关键影响因素,此方法将对大型工程质量管理有一定的指导作用。     

谈大型及特殊建设工程消防安全及对策

通过对大型及特殊建设工程发展趋势的调查,重点分析了大型及特殊建设工程的消防安全形势,提出了大型及特殊建设工程的消防安全对策,以供大型及特殊建设工程消防安全管理参考。     

大型煤炭企业内部供应链构建及相关研究

本文以大型煤炭企业为研究对象,界定了大型煤炭企业内部供应链概念,分析了大型煤炭企业内部供应链内涵。最后指出了煤炭企业的不确定性研究和供需突发事件研究对大型煤炭企业的必要性。     

大型公共建筑用电能耗预测模型及预测数据

本文通过对我国大型公共建筑的能源消耗的分析,首先介绍了我国大型公共建筑用电能耗的机构;然后介绍了我国大型公共建筑空调系统用电能耗影响的因素;其次介绍了大型公共建筑的空调系统用电能耗的预测方法;最后介绍了大型公共建筑能耗预测和分析系统的设计。     

我国大型公共建筑节能改造EPC模式选择研究

推进合同能源管理模式在大型公共建筑节能改造市场中的应用,是解决我国大型公建能效低、改造难的有效途径.结合合同能源管理模式分析,总结大型公建节能改造现状,从大型公建业主、节能服务公司以及外部环境等方面探讨大型公建节能改造合同能源管理模式选择的影响因素,基于模糊综合分析,构建具有实用性和操作性的大型公共建筑节能改造合同能源...     

大型水泥集团的现状

概述我国水泥工业大型水泥集团的现状,在行业中的地位及大型水泥集团区域分布情况,分析了大型水泥集团的经济运行状况,指出了当前大型水泥集团所存在的主要问题。     

矩阵重排序算法在结构分析快速求解中的应用

结构有限元分析中最基本的计算是大规模线性方程组的求解,求解方法有直接法和迭代法两种.由于收敛性问题迭代法的应用受到很大限制,而解决求解规模和速度问题是直接法应用的关键.用直接法求解线性方程组,可通过减小矩阵的带宽与轮廓来减少数据存贮量及浮点运算次数,从而提高求解规模和速度.本文基于图论原理并针对结构总刚矩阵的一维变带宽存贮特点,对RCM算法进行了改进,以减少总刚矩阵的轮廓及带宽.算例表明,本文提出的在大规模线性方程组求解中采用改进的RCM算法快速求解技术,其算法是高效的,编制的计算程序是稳定、可靠的.     

A beam finite element for non-linear analyses of thin-walled elements

The aim of the present paper is to investigate a theoretical and numerical model which is able to study the behaviour of thin-walled beams with open cross section in presence of large torsion. The presented model takes into account for large torsion, linear and non-linear warping currently named shortening effects, pre-buckling deformation and flexural–torsional coupling. In numerical analysis, a 3D beam with two nodes and seven degrees of freedom per node is adopted. The equilibrium equations and the material behaviour are derived in discrete form without assumption on torsion angle amplitude. Due to large torsion context, all the equilibrium equations are non-linear and highly coupled. The linear behaviour is made possible by disregarding non-linear terms. For non-linear behaviour and stability, the tangent stiffness matrix is carried out. Due to large torsion context, new matrices are present. The element is incorporated in a homemade finite element code. Newton–Raphson iterative methods are used with different control parameters. In order to prove the efficiency of the model many examples are presented in linear and non-linear behaviour with presence of bifurcations.     

CPU-GPU混合计算构架在岩土工程有限元分析中的应用

计算机技术的快速发展促进了岩土工程数值模拟技术的进步和有限元仿真技术的应用。对于三维有限元建模,有限元离散所获得的线性方程系统规 模较大,这些线性方程系统的求解通常支配着整个有限元计算的时间。为了提高有限元求解的效率,需要采用先进的基础迭代算法和高性能计算构架。使用 性价比较高的GPU计算硬件对目前流行的预处理Krylov子空间迭代法进行了加速,重点研究了GPU对Krylov子空间迭代过程中矩阵矢量乘积的加速效果。由于 预处理迭代方法的计算性能依赖于计算构架,采用数值算例对几种流行的预处理迭代方法在不同计算构架下的计算性能进行了评测,对在不同计算构架下采 用何种预处理迭代方法给出了相应的建议。     

Direct‐Iterative Hybrid Solution in Nonlinear Dynamic Structural Analysis

Although many advanced sparse direct solvers are widely used in structural analysis, these often require longer computing times than iterative solvers for well‐conditioned structural systems. However, iterative solvers cannot efficiently solve an ill‐conditioned system when a structure becomes highly nonlinear. This work proposes a hybrid solution integrating a direct solver and an iterative solver to reduce overall computing time in solving a series of linear equations arising from nonlinear dynamic structural analysis. The hybrid solution selects the iterative solver, which reuses the factorized matrices for preconditioning, and switches to the direct solver in the initial stage or when factorized matrices need updating. The performance of the hybrid solution is tested on the OpenSees platform. The results show that the hybrid solution outperforms the direct solver, even when the structure becomes highly nonlinear during analysis.     

Nonlinear aeroelastic response of slender wings based on Wagner function

This paper presents a method for nonlinear aeroelastic analysis of Human Powered Aircraft (HPA) wings. In this type of aircraft there is a long, highly flexible wing. Wing flexibility, coupled with long wing span can lead to large deflections during normal flight operation; therefore, a wing in vertical and torsional motion using the second-order form of nonlinear general flexible Euler–Bernoulli beam equations is used for structural modeling. Unsteady linear aerodynamic theory based on Wagner function is used for determination of aerodynamic loading on the wing. Combining these two types of formulations yields the nonlinear integro-differentials aeroelastic equations. Using the Galerkin's method and modes summation technique, the governing equations will be solved by introducing an iterative numerical method to predict the aeroelastic response of the problem. The obtained results for a test case are compared with those of linear study which shows good agreement for speeds less than the flutter speed, but the nonlinear model shows limit cycle oscillations for the wing beyond the flutter boundary.     

Nonlinear free vibration of tapered Mindlin plates with edges elastically restrained against rotation using DQM

Large amplitude free vibration analyses of tapered Mindlin rectangular plates with elastically restrained against rotation edges are investigated using different differential quadrature method (DQM). The governing equations are based on the first-order shear deformation plate theory in conjunction with Green's strain and von Karman assumption. The spatial derivatives are discretized using DQM and the harmonic balance method is used to transform the resulting differential equations into frequency domain. A direct iterative method is used to solve the nonlinear eigenvalue system of equations. The convergence of the method is shown and their accuracy is demonstrated by comparing the results with those of the limiting cases, i.e. nonlinear free vibration analysis of plates with classical boundary conditions and also linear free vibration analysis of tapered plates. The effects of the elastic restraint coefficient at the edges and the geometrical parameters on the ratio of the nonlinear natural frequency to linear natural frequency of plates with linearly and bi-linearly varying thickness are studied.     

Lateral post-buckling analysis of thin-walled open section beams

Thin-walled beams with open sections are studied using a nonlinear model. This model is developed in the context of large displacements and small deformations, by accounting for bending-bending and bending-torsion couplings. The warping and shortening effects are considered in the torsion equilibrium equation. The governing coupled equilibrium equations obtained from Galerkin’s method are solved by a Newton–Raphson iterative process. It is established that the buckling loads are highly dependent on the pre-buckling deformations of the beam. The bifurcated branches are unstable and strongly influenced by shortening effects. Some comparisons are presented with the solutions commonly used in linear stability, like in the standard European steel code (Eurocode 3). The regular solutions appear to be very conservative, especially for I sections with large flanges.     

Linear Form Finding Approach for Regular and Irregular Single Layer Prism Tensegrity

In an irregular prism tensegrity, the number of force equilibrium equations is less than the number of unknown parameters of nodal coordinates and member force ratios. As a result, the form-finding process normally becomes nonlinear with additional conditions or needs to be carried out with the use of iterative procedures. For cases of irregular prism tensegrity which involves large number of members, it was found that previously proposed methods of form-finding are not practical. Moreover, there is a need for a form-finding approach which is able to cater to different requirements on final configuration. In this paper, the length relation condition is introduced to be used in combination with the force equilibrium equation. With the combined use of length relation and equilibrium conditions, a linear form-finding approach for irregular prism tensegrity was successfully formulated and developed. An easy-to-use interactive form-finding tool has been developed which can be used for form-finding of irregular prism tensegrities with large number of elements as well as under diverse specific requirements on their configurations.     

沉入式圆筒结构与土相互作用的模式及位移计算方法

本文提出了沉入式无底大直径圆筒结构筒体与土协同工作的一种分析模型.该模型假设土体中任一点对筒壁竖向位移的剪切变形刚度系数与该点的土下深度和筒体水平位移成正比.在这一假设下得到的求解筒体位移的平衡方程为—非线性方程组,为此建立了求解这一方程组的迭代算法,并用模型试验结果对该模型及其计算方法进行了检验.     

边坡稳定性分析最小二乘法

利用经典土压力理论设定合理土条推力线位置,对土条底滑面采用摩尔-库伦破坏准则,根据静力平衡及力矩平衡条件建立线性超定方程组,应用MATLAB软件基于最小二乘法原理对此方程组求解,得到比较精确的安全系数。该法从设定合理土条推力线位置出发,避免了对条间力函数的不合理设定,采用MATLAB求解线性超定方程组得解,克服了求解非线性方程组不能迭代收敛得解的缺点,经算例验证其在精度方面比较可靠,对于评价边坡的稳定性具有参考意义。