Object Oriented Programming and Numerical Methods

Abstract: A generally applicable mathematical model, tailored for use on a Personal Computer, as the design tool to simulate unsteady flood flow in a network of interconnected rivers has been developed and applied to the Sham Chun River along the border between Hong Kong and the People's Republic of China. The effect on the improved Sham Chun River due to the proposed river training in the River Indus, one of its tributaries, is evaluated. The one-dimensional unsteady flow model itself is broadly applicable to a wide range of hydrologic conditions and varying field situations. It incorporates real hydraulic features including branched channels and 'tidal flats' flooding and drying. The time history of water stages and discharges are computed at any desired location throughout the connected essentially one-dimensional channel network subject to initial and boundary conditions. Details are given of techniques adapted in using the computational scheme to quantify the unsteady flow condition and the means to assure an efficient numerical solution as well as to verify the accuracy of the computed outputs by subjection to carefully selected schematic simplified test cases and real prototype cases with numerical solution method is a useful predictive engineering tool in river design.     

多种数值积分方法比较分析

数值积分是计算方法或数值分析理论中非常重要的内容,数值积分方法也是解决实际计算问题的重要方法。本文对几种常用的数值积分方法进行了简要的分析,并用这几种方法对被积函数是普通函数做了数值积分,龙贝格（Romberg）积分方法效果较好。     

用数字谐波法检测MOA的试验研究

给出当前MOA的检测方法并指出了不足,在此基础上提出一种基于A/D转换和微机处理的试验方法数字谐波法。针对MOA检测中的干扰方式如系统谐波、PT相移以及数字波形失真提出了相应的抗干扰措施,取得了一定的效果。     

多种微分方程数值计算方法分析

数值微分方程的数值解法是计算方法、数值分析理论中非常重要的内容,数值微分方法也是解决实际计算问题的重要方法。本文对几种常用的数值微分方法进行了简要的分析,并用这几种方法对具有光滑性质的被积函数进行数值计算,龙格-库塔方法和4阶阿达姆斯方法的数值计算稳定性和计算精度都比较好。     

Numerical Methods to Simulate and Visualize Detailed Crane Activities

Abstract:   Virtual construction allows engineers to simulate and visualize construction progress on computer before commencing the real project and is becoming an important technique to manage fast-track and complicated construction projects. One major consideration for virtual construction is the simulation of the operation of construction equipment for a construction project. This research specifically focuses on developing a mathematical model to support the simulation and visualization of cranes, the most critical equipment in terms of project controls. This model is composed of two submodels—a kinematics model and a dynamic model. The kinematics model is to present the crane components controlled by the operators. The dynamic model is to present the dynamic behavior in suspended system (including the cable and rigging object), which cannot be controlled directly by the operators. To verify the feasibility of these methods, a computer program that simulates and visualizes detailed crane activities was developed. This program supports the real-time visualization of crane activities with high degree of reality accuracy and also, enables the detailed simulation of long-term construction projects .     

土工数值分析的回顾与展望

本文首先对力学领域内三种最常用数值方法(差分法、有限元法和边界元法)的本质及它们的各自优点作了简要说明。然后回顾这三种方法分别自40年代、60年代及70年代以来的发展以及在土工上的应用。最后,从加强土的本构关系的研究、改善数值分析本身以及工地实测与计算的对比等方面,对土工数值分析今后的发展,提出了具体意见。     

表征真实骨料形态的三维数值骨料建模

利用图像处理技术将骨料截面轮廓处理为二值图像,识别出各独立轮廓的形态特征后获取Hurst指数值的统计学规律,并使用改进的分形布朗运动(FBM)生成随机的数值骨料截面轮廓.使用该轮廓作为垂直于构建轴线的三维骨料上下两部分的连接面,基于改进的随机中点位移法,分别建立三维骨料的上曲面和下曲面并组装成完整的三维骨料模型.按相同纵长比生成的数值骨料与真实骨料具有相近的轮廓、扁平比和球度,且随机生成的数值骨料样本库与实测的真实骨料样本库具有类似的体积分布规律.按级配生成数值骨料并投放生成圆柱形沥青混凝土数值试件,相同工况下的仿真结果与单轴压缩蠕变试验数据的趋势吻合.     

Model Test and Numerical Analysis Methods in Tunnel Excavation Problem

Tunnels serve various functions such as in subway systems, underground electric power lines, gas pipes, telecommunication lines, water supplies and sewer lines and many other pipelines. The trend of tunnel construction is toward deeper and longer tunnels. In addition, the excavation of tunnels in difficult ground conditions is now not uncommon, though the tunnels themselves are still difficult to construct. Advanced studying methods have been developed for the prediction, monitoring and evaluation of the performance of tunnels and ground. Today, experimental methods and analytical methods are the main approaches used in tunnel studies. In this paper, the present state of tunnel construction and the main study methods are discussed, and the various experimental and analysis methods and their usage are compared. Tunnel excavation is very complex because it involves soils, structure and interaction problems. There is no one perfect studying method, though there are good combinations of numerical analyses and experimental methods which provide the optimum approach for solving tunnel related problems.     

建筑外墙热工性能现场检测方法与数值模拟分析

热流计法是现有测试墙体热物性能最常用的方法,但由于周围复杂环境的影响,墙体的导热过程很难达到一维稳态工况。近些年来,数值模拟与实验相结合是墙体热阻测定的一个必然趋势。本文首先利用热流计法测试建筑外墙的导热热阻,然后运用FLUENT对一维导热区和四季典型日进行分析计算,并对测试热阻进行修正,得到更准确的数据。     

核电厂土方工程计算方法探讨

文章重点叙述人工模拟建立DTM模型进行两期数据比较计算彭泽核电正挖阶段不同时期挖、填土石方量的方法,并通过方格网法计算结果进行校核,以此互相论证计算结果的可靠性。     

建筑结构连续倒塌的数值模拟方法对比研究

建筑结构连续倒塌,是一类由偶然作用引起,可能造成重大生命财产损失的结构安全事故。针对建筑结构连续倒塌的数值模拟问题,本文分析了结构倒塌过程中面临的力学计算难点,对比研究了常用的数值模拟方法,并介绍了作者提出的质点元法。     

解析法和数值法在基坑降水和回灌系统设计中的综合应用

以卡塔尔某基坑降水工程为例,综合运用解析法和数值法对基坑降水和回灌系统进行设计计算,通过对比分析和相互验证,解析法和数值法的计算结果基本一致,并与工程现场实际监测的地下水位和水量较好地吻合,表明解析法和数值法的综合应用是一种可靠的基坑降水和回灌系统的设计方法。     

混凝土强度非破损检测中修正方法的模拟比较

混凝土强度的非破损检测方法有回弹法、超声法和超声回弹综合法等,其推定原则是先按照基准强度曲线求得测区的混凝土计算强度(相当于1块立方体试块的强度),然后根据若干个测区的推定强度,对1个构件或1批同强度等级混凝土的构件,或对采用相同强度等级混凝土连续整体浇筑的整个结构的混凝土强度作出总体评价,作为验收的辅助依据。但现场混凝土的原材料、配合比以及施工条件等不可能与基准强度曲线的制作条件完全一致,因此,强度计算值往往偏差较大。为了提高结果的可靠性,可结合现场情况对基准曲线进行修正。《超声回弹综合法检测混凝土强度技…     

北京地铁西四站暗挖段施工工法数值模拟研究

北京地铁西四车站暗挖段,地处闹市,地面交通繁忙,地质条件复杂,施工难度较大,因此在具体施工前对其施工工法和洞室稳定性进行细致研究是十分必要的。本文采用有限差分程序FLAC3D对施工方案中设计的管棚、注浆、喷层等支护措施和支护效果进行数值模拟分析,对具体工法做出了定量的评价,对后期工程的施工有很大的参考价值和一定的指导作用。     

非比例阻尼结构体系动力计算显式算法及其稳定性分析

讨论了当前几种用于非比例阻尼结构体系动力计算的显式算法稳定性机理,结合此类算法递推格式的稳定性特点,提出了一种适用于非比例阻尼结构体系动力计算的改进显式算法.基于多自由度体系,采用以单元Rayleigh阻尼矩阵组装形成整体阻尼矩阵的方法,借助开源有限元软件OpenSees的二次开发,对中心差分法及前述显式算法进行了稳定性分析和讨论,并给出了稳定性判定的建议.     

双连拱隧道不同施工工法的施工力学机理数值分析

为了研究双连拱隧道不同施工工法下的位移和受力特征,确保施工安全顺利进行,依托惠州市四环路南段西坑东双连拱隧道工程,采用MIDAS有限元软件分别对Ⅴ级围岩下三导洞法施工、Ⅳ级围岩下中导洞法施工进行模拟,得到拱顶沉降、洞身位移、锚杆轴力以及中隔墙内力的计算结果。通过对结果进行对比分析,为西坑东双连拱隧道的施工提供相关建议。     

堤坝防渗墙完整性快速检测方法及数值仿真

堤坝防渗墙的质量安全关乎国计民生,寻求有效方法快速检测防渗墙缺陷十分重要。弹性波映像法是基于弹性波反射原理的无损检测方法,具备检测效率高、结果直观等特点。针对堤坝防渗墙的常见缺陷类型,以弹性波在堤坝模型中的传播特性为理论基础,采用数值模拟方法分别分析了弹性波在防渗墙竖向通缝缺陷、防渗墙深度不足、空洞缺陷处的传播特性,根据计算结果建立响应能量与防渗墙缺陷之间的关系,为堤坝防渗墙缺陷的检测提供了一种快速的评价方法。     

不同通风方式与地板供冷结合的热环境模拟研究

利用计算流体动力学方法,通过PHOENICS分别对辐射地板与置换通风(DV),层式通风(SV)和混合通风(MV)相结合的复合系统进行模拟分析.得出不同地板温度,送风方式以及送风参数的室内速度和温度分布.结果 表明在不考虑室内污染物的情况下,通过改变送风温度,速度以及地板温度时,置换通风中由垂直温差引起的竖直不满意率略高...