共查询到19条相似文献,搜索用时 78 毫秒
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无单元伽辽金法解固结问题 总被引:3,自引:1,他引:3
王志亮 《岩石力学与工程学报》2004,23(7):1141-1145
根据土体中平衡微分方程及连续性方程,结合边界条件及初始条件,应用无网格伽辽金法推导出土体二维Biot固结的系统方程并编制了相应的无网格程序。该法基于特定影响域中的一系列随机分布的结点,采用移动最小二乘法进行多项式插值构造形函数,同时,采用罚函数法处理本质边界条件,应用Crank-Nicolson积分方案对时间域进行离散。最后,通过一算例与其理论上精确解及有限元结果相比较,说明了该法的精确性和可行性。 相似文献
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用无网格伽辽金法研究了热弹性薄板的弯曲问题,由移动最小二乘法和虚位移原理得到热弹性板的近似场函数和刚度方程,编制相应的无网格法计算程序,并给出算例.结果表明了该方法可行,且具有广泛的工程应用前景. 相似文献
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无网格伽辽金法求解固结方程的数值误差分析 总被引:2,自引:1,他引:1
作为一种新的计算方法,无网格伽辽金法(EFGM)有着自己的构成特点,在求解固结方程时也会产生数值误差。讨论了EFGM中一些降低数值震荡误差的影响因素和解决方法,首次给出了固结EFGM离散方程的误差分析不等式,针对该公式提出了在EFGM计算中降低误差的参数最优选取方法。最后,通过二维条形地基理论模型的数值试验,验证了积分Cell精细程度对EFGM求解固结方程的初始孔压精度和稳定性的影响。 相似文献
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自然单元法采用自然邻点插值方法在全域构造近似函数和试函数,该方法基于整个求解域内离散结点的Voronoi结构。当采用标准Galerkin法形成系统的平衡控制方程时,对弱形式的积分通常在Voronoi图的对偶图Delaunay三角形内进行,但由于自然邻接插值形函数的特性,自然单元法数值积分存在明显误差。分析了自然单元法数值积分产生误差的各种可能的原因,并提出使用蒙特卡罗方法解决这一问题。该方法权系数直接与精度相关,确定方法简单有效。采用Delaunay三角形内布积分点,使得这种概率积分结果接近数学期望。给出最少积分点数的确定方法,尽可能提高蒙特卡罗积分的计算效率。通过分片试验和悬臂梁等算例验证蒙特卡罗方法解决这些误差的可行性和有效性。 相似文献
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指出无网格伽辽金法模拟裂纹尖端附近(0~0.1a,a为裂纹长度)应力场时可采用裂纹尖端节点加密和扩展基函数两种方法。对两种方法的模拟结果进行了分析,发现加密节点布置方案对模拟结果影响很大,对节点密度梯度过大使模拟结果产生振荡的原因进行分析。对处理不连续域问题的方法进行了探讨,并提出合理化建议。 相似文献
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基于复数表达的随机渗流研究 总被引:1,自引:0,他引:1
以复数形式表示渗透系数,将其变异值设置为复数的虚部.利用有限单元法,通过求解复系数线性方程组计算随机渗流问题,并编制相应程序,计算结点水头和水头变异值.在应用蒙特卡罗法进行渗流计算时,仅考虑帷幕渗透系数的变异,并假设其服从均匀分布.选取水头均值与水头标准差为蒙特卡罗法渗流计算的统计特征值.从数值方面分析了基于复数表达的随机渗流计算所得的水头值及水头变异值与蒙特卡罗法计算的水头均值及标准差之间的关系,验证了所用方法在模拟随机渗流场方面的正确性和可行性.为大型复杂问题的大变异性求解提供了方便快捷的计算方法. 相似文献
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对黄土地区4处不同工程点取得实测数据后,利用GeoStudio软件,用蒙特卡罗法和点估计法进行计算,并对两种计算步骤和计算结果进行比较,发现蒙特卡罗法利用GeoStudio计算简单精确,而在各状态变量未知时,点估计法在变量较少时计算也非常方便,其结果与蒙特卡罗法相当相近。 相似文献
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A Monte Carlo sampling method based on both first- and second-order approximations to the failure region is proposed for the calculation of structural failure probabilities. The method applies to smooth failure surfaes and involves consideration of the hyperplane tangential to the failure surface at the design point and a hyperparabolic approximation to the failure surface. The efficiency of the method is illustrated with two examples and comparisons made with some other Monte Carlo methods. 相似文献
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Yuchuan Du Yuanjing Geng Lijun Sun 《Frontiers of Architecture and Civil Engineering in China》2009,3(2):195-203
For a local area road network, the available traffic data of traveling are the flow volumes in the key intersections, not
the complete OD matrix. Considering the circumstance characteristic and the data availability of a local area road network,
a new model for traffic assignment based on Monte Carlo simulation of intersection turning movement is provided in this paper.
For good stability in temporal sequence, turning ratio is adopted as the important parameter of this model. The formulation
for local area road network assignment problems is proposed on the assumption of random turning behavior. The traffic assignment
model based on the Monte Carlo method has been used in traffic analysis for an actual urban road network. The results comparing
surveying traffic flow data and determining flow data by the previous model verify the applicability and validity of the proposed
methodology. 相似文献
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蒙特卡罗方法应用研究 总被引:17,自引:2,他引:15
介绍了蒙特卡罗(Monte Carlo)方法,即随机模拟方法,提出了任意分布随机数的产生原理及方法,并用算例说明蒙特卡罗方法的使用过程,同时用2χ拟和优度法验证了其合理性. 相似文献
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Eisuke Togashi 《Journal of Building Performance Simulation》2019,12(4):504-522
Demonstrating the economic rationality of investments in energy efficiency is a necessary step in reducing the energy consumption of buildings. Generally, financial instruments are evaluated according to both the return on investment and the risk. However, many previous studies of energy efficiency investments in buildings are based on deterministic scenarios and do not evaluate the risk levels of these investments. Therefore, in this study, we clarify the risk involved in an energy-saving investment by calculating the probability distribution of the energy reduction and evaluating the result using financial engineering methods. We first develop a stochastic model of various conditions that affect the energy consumption of a building. These conditions include weather processes, office worker behavior, tenant characteristics, and tenant replacements. Next, we construct a prediction model of a building's energy consumption, and we use our stochastic model to create the boundary conditions of this prediction model. By repeatedly performing energy consumption predictions using the Monte Carlo method, we can obtain the probability distribution for building energy consumption. Finally, given this probability distribution, we evaluate energy efficiency investments using financial engineering methods. Based on the discounted cash flow distribution, we calculate the risk premium of each energy efficiency investment, and, based on the variance and covariance matrix of the internal rate of return of each energy efficiency investment, we find the optimal investment ratio. 相似文献
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采用可靠度分析的蒙特卡罗法 ,建立了加筋土边坡稳定极限状态方程 ,对其可靠度进行了分析 ,并结合工程事例 ,讨论了土性参数的均值和变异系数对可靠度指标的不同影响 ,指出可靠指标度量加筋土边坡稳定性更合理。 相似文献