共查询到16条相似文献,搜索用时 500 毫秒
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二阶非定常多宗量热传导反问题的正则解 总被引:1,自引:0,他引:1
引入Bregman距离函数及其加权函数作为正则项,应用Tikhonov正则
化方法,对二阶非定常多宗量热传导反问题进行求解. 利用测量信息和计算信息构造最小二
乘函数,将多宗量反演识别问题转化为一个优化问题. 空间上采用8节点等参元进行离散,
时域上采用时域精细算法进行离散,建立了二阶非定常多宗量热传导问题的有限元正/反演数
值模型. 该模型不仅考虑了非均质和参数分布的影响,而且也便于正反演问题的敏度分析,
可对导热系数和边界条件等宗量进行有效的单一和组合识别. 给出了相关的数值验证,对信
息测量误差以及不同正则项的计算效率作了探讨. 数值结果表明,该方法能够对二阶非定常
多宗量热传导反问题进行有效的求解,并具有较高的计算精度. 相似文献
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共轭梯度法求解非线性多宗量稳态传热反问题 总被引:3,自引:0,他引:3
应用共轭梯度法求解非线性多宗量稳态热传导反问题。采用八节点的等参单元在空间上进行离散,建立了便于敏度分析的非线性正演和反演的有限元模型,可直接求导进行敏度分析。给出了相关的数值验证,对测量误差及测点数目的影响作了初步探讨,结果表明,采用的算法能够对非线性稳态热传导中导热系数和边界条件联合反问题进行有效的求解,并具有较高精度。 相似文献
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不可压流体饱和多孔弹性梁的变分原理及有限元方法 总被引:3,自引:1,他引:2
基于不可压饱和多孔弹性梁动力弯曲的数学模型,建立了以多孔弹性梁挠度和孔隙流体压力等效力偶为宗量的Gurtin型变分原理,并给出了特殊边界条件下解耦时的仅以挠度为宗量的变分原理.同时,作为动力响应的退化情形,讨论了拟静态情形下的相应变分原理.根据所建立的变分原理,导出了一个有限元离散公式.由于Gurtin型变分原理是关于时间的卷积型的泛函,空间的有限元离散导致一个关于时间的对称微分一积分方程组,此方程组可进一步转化为常微分方程组.利用隐式Euler法,给出了时间区域的计算格式.作为一个数值例子,分析了饱和多孔弹性悬臂梁在自由端简谐载荷作用下的动力响应,分析了流相与固相相互作用对饱和多孔弹性悬臂梁动力响应的影响. 相似文献
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蚁群算法求解二维拉压不同模量反问题 总被引:2,自引:2,他引:0
利用光滑函数技术对二维拉压不同模量本构关系进行光滑化处理,采用初应力方法求解二维拉压不同模量正问题的有限元方程。在此基础上,建立了基于连续域蚁群算法的二维拉压不同模量反问题的数值求解模型,考虑了区域非均质的影响,实现了对拉压弹性模量和泊松比的单一/组合识别。通过两个数值算例,对所提算法进行了数值验证,分别探讨了蚁群算法相关参数、测点分布和数据噪音等对识别结果的影响。数值验证表明,所提算法可有效地求解二维拉压不同模量反问题,并具有较好的计算精度。 相似文献
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基于独立分量分析的多源动态载荷识别方法 总被引:1,自引:0,他引:1
提出了基于独立分量分析的多源动态载荷识别方法, 解决了在结构系统未知的情况下载荷波形的识别问题. 该方法基于结构在多源动态载荷作用下, 其响应是载荷与对应的结构脉冲响应卷积的原理, 并假设载荷源相互统计独立. 与既有的载荷识别方法相比,该识别方法特点表现在: 结构质量, 刚度及阻尼等信息可以完全未知, 但以实际载荷间的独立性为优化目标; 用互信息来度量识别载荷间的独立性, 通过梯度下降算法取消识别载荷间的各阶相关性, 使识别载荷间基本满足相互独立; 从波形的角度来进行载荷识别.通过数值仿真表明: 该方法对测点, 噪声, 不同载荷形式及不同结构有较好的鲁棒性; 识别载荷与实际载荷在归一化条件下, 识别载荷与实际载荷相关性系数约为1. 相似文献
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PRECISE INTEGRAL ALGORITHM BASED SOLUTION FOR TRANSIENT INVERSE HEAT CONDUCTION PROBLEMS WITH MULTI-VARIABLES 总被引:2,自引:0,他引:2
IntroductionIHCPs (InverseHeatConductionProblems)arecloselyassociatedwithmanyengineeringaspects,andwelldocumentedintheliteratures,coveringtheidentificationsofthermalparameters[1,2 ],boundaryshapes[3],boundaryconditions[4 ]andsource_relatedterms[5 ,6 ]etc .Howeveritseemsthatonlylittleworkisdirectlyconcernedwithmulti_variablesidentificationsbyauthors’knowledge.Tsengetal.presentedanapproachtodeterminingtwokindsofvariables[7],butonlygavefewnumericalexamplestodeterminethemsimultaneously .Thesol… 相似文献
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This paper presents an improved precise integration algorithm for transient analysis of heat transfer and some other problems.
The original precise integration method is improved by means of the inverse accuracy analysis so that the parameterN, which has been taken as a constant and an independent parameter without consideration of the problems in the original method,
can be generated automatically by the algorithm itself. Thus, the improved algorithm is adaptive and the accuracy of the algorithm
is not dependent on the length of the time step in the integration process. It is shown that the numerical results obtained
by the method proposed are more accurate than those obtained by the conventional time integration methods such as the difference
method and others. Four examples are given to demonstrate the validity, accuracy and efficiency of the new method.
Project supported by the National Natural Science Foundation of China (No. 19872016, 19872017), the National Key Basic Research
Special Foundation (G1999032805) and the Foundation for University Key Teachers by the Ministry of Education of China. 相似文献
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A novel method is suggested to deal with so-called uncertainty inverse problems (UIPs) which are a class of inverse problems with uncertainty in the system parameters of the forward model.
Interval which represents a closed bounded set of real numbers is used to model and characterize the uncertainty in our formulation,
and hence only the bounds of the uncertainty of the system parameters are needed. For a specific input vector, the possible
values of the outputs form an interval vector because of the uncertainty. An error function is defined using the measured interval vector of the outputs and those computed
using a forward model. The UIP is then formulated as an optimization problem which minimizes the error function. To improve
the optimization efficiency, an interval forward model is constructed based on the interval analysis method which can calculate
very efficiently the bounds of the outputs caused by the uncertainty of the system parameters. The present method is applied
to a complex inverse problem, namely material characterization of composite laminates using elastic waves. Uncertainty of
load is considered, and the hybrid numerical method (HNM) is used to compute the transient displacement responses. The engineering
constants of two kinds of laminates are successfully identified using the simulated measurements of the outputs. 相似文献
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In this paper, solution of inverse problems in heat conduction transient fields is investigated. For this purpose, a new time-domain version of linear sampling method (TDLSM) is developed for cavity detection in a heat conductor. The linear sampling method (LSM) is an effective approach to image the geometrical features of unknown targets. Although this method has been used in the context of inverse scattering problems such as solid, acoustics, and electromagnetism, there is no specific attempt to apply this method to identification of cavities in heat conductors. This study emphasizes the implementation of the LSM in the time-domain fields using finite element method. A set of numerical simulations on two-dimensional transient heat conduction problems is presented to highlight many effective features of the proposed TDLSM fast qualitative identification method. 相似文献
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《Experimental Thermal and Fluid Science》2005,29(2):227-238
In this paper, a new experimental method of phase interface motion control with time dependent boundary cooling is presented for ice–water solidification problems. A numerical method for inverse heat transfer problems was developed to predict the transient boundary conditions, which produce a prescribed phase interface motion. In the experimental study, the predicted boundary temperatures from the numerical simulation were used to control the ice–water interface movement for various specified interface motions. Two cases of different phase interface velocities were considered. Water supercooling was observed during each experiment. A time delay in the thermal control was calculated based on an analytical solution. Close agreement between measured data and specified interface motion was achieved for the ice–water solidification problems. 相似文献