Accurately solving transient nonlinear inverse heat conduction problems in complex structures is of great importance to provide key parameters for modeling coupled heat transfer process and the structure’s optimizati...Accurately solving transient nonlinear inverse heat conduction problems in complex structures is of great importance to provide key parameters for modeling coupled heat transfer process and the structure’s optimization design.The finite element method in ABAQUS is employed to solve the direct transient nonlinear heat conduction problem.Improved particle swarm optimization(PSO)method is developed and used to solve the transient nonlinear inverse problem.To investigate the inverse performances,some numerical tests are provided.Boundary conditions at inaccessible surfaces of a scramjet combustor with the regenerative cooling system are inversely identified.The results show that the new methodology can accurately and efficiently determine the boundary conditions in the scramjet combustor with the regenerative cooling system.By solving the transient nonlinear inverse problem,the improved particle swarm optimization for solving the transient nonlinear inverse heat conduction problem in a complex structure is verified.展开更多
Exploring new acoustic parameters is essential to develop a noninvasive imaging technique for the surgery of silicone oil tamponades. In this study, the acoustic nonlinearity parameters B/A of varied silicone oil samp...Exploring new acoustic parameters is essential to develop a noninvasive imaging technique for the surgery of silicone oil tamponades. In this study, the acoustic nonlinearity parameters B/A of varied silicone oil samples （e.g., linear or hyper-branched） are experimentally measured by using a modified thermodynamic method. The results show that： （i） when the concentration of the silicone oil with a molecular weight of 5 × 10^4 increases from 0.5 g/100 ml to 8 g/100 ml, the corresponding B/A value increases by about 18%, but the acoustic velocity only increases by about 0.1%; （ii） when the molecular weight of the hyper-branched silicone oil is enhanced from 2 × 10^5 to 1 × 10^6, the B/A value increases by about 22%, while the acoustic velocity is only raised by about 0.2%. This study suggests that the B/A parameter of the silicone oil is more sensitive to the change in its molecular structure than that of the acoustic velocity. Thus, the B/A parameter might be utilized as an effective index for the development and optimization of the noninvasive imaging of the surgery of silicone oil tamponades.展开更多
How to accelerate the convergence speed and avoid computing the inversion of a Jacobian matrix is important in the solution of nonlinear algebraic equations(NAEs).This paper develops an approach with a splitting-linea...How to accelerate the convergence speed and avoid computing the inversion of a Jacobian matrix is important in the solution of nonlinear algebraic equations(NAEs).This paper develops an approach with a splitting-linearizing technique based on the nonlinear term to reduce the effect of the nonlinear terms.We decompose the nonlinear terms in the NAEs through a splitting parameter and then linearize the NAEs around the values at the previous step to a linear system.Through the maximal orthogonal projection concept,to minimize a merit function within a selected interval of splitting parameters,the optimal parameters can be quickly determined.In each step,a linear system is solved by the Gaussian elimination method,and the whole iteration procedure is convergent very fast.Several numerical tests show the high performance of the optimal split-linearization iterative method(OSLIM).展开更多
鉴于调谐质量阻尼器(tuned mass damper,TMD)耗能结构在考虑土-结构相互作用(soil-structure interaction,SSI)时,随机地震响应分析方法较为复杂,本文提出一种计算响应谱矩和方差的简明解法,并深入研究SSI效应下结构随机地震动的响应特...鉴于调谐质量阻尼器(tuned mass damper,TMD)耗能结构在考虑土-结构相互作用(soil-structure interaction,SSI)时,随机地震响应分析方法较为复杂,本文提出一种计算响应谱矩和方差的简明解法,并深入研究SSI效应下结构随机地震动的响应特性。首先,根据达朗贝尔原理建立考虑SSI效应的TMD耗能结构的地震动方程,利用有限元动力技术建立基于实模态分解法的TMD耗能结构地震动一般方程;其次,利用功率谱二次式分解法推导出基于杜修力地震动激励的结构位移、TMD位移、基础平动和转动位移响应的0阶—2阶谱矩的简明封闭解;最后,通过算例,验证所提方法并研究了考虑SSI效应的TMD耗能结构地震响应特性。结果表明:在基础固定的情况下,场地土为中硬土、中软土和软弱土时,以层间位移为指标的动力可靠度、结构顶层位移逐渐变大,SSI效应逐渐显著;TMD在各种场地条件下都具有良好的减震效果,且最优参数受场地影响较小。与传统方法相比,本文方法计算过程更为简便,精度更高,能更高效地应用于实际工程。展开更多
基金supported by the National Natural Science Foundation of China(Nos.12172078,51576026)Fundamental Research Funds for the Central Universities in China(No.DUT21LK04)。
文摘Accurately solving transient nonlinear inverse heat conduction problems in complex structures is of great importance to provide key parameters for modeling coupled heat transfer process and the structure’s optimization design.The finite element method in ABAQUS is employed to solve the direct transient nonlinear heat conduction problem.Improved particle swarm optimization(PSO)method is developed and used to solve the transient nonlinear inverse problem.To investigate the inverse performances,some numerical tests are provided.Boundary conditions at inaccessible surfaces of a scramjet combustor with the regenerative cooling system are inversely identified.The results show that the new methodology can accurately and efficiently determine the boundary conditions in the scramjet combustor with the regenerative cooling system.By solving the transient nonlinear inverse problem,the improved particle swarm optimization for solving the transient nonlinear inverse heat conduction problem in a complex structure is verified.
基金Project supported by the National Basic Research Program of China(Grant No.2011CB707900)the National Natural Science Foundation of China(Grant Nos.81127901,11174141,61072027,and 11374155)the Natural Science Foundation of Jiangsu Province,China(Grant No.BE2011110)
文摘Exploring new acoustic parameters is essential to develop a noninvasive imaging technique for the surgery of silicone oil tamponades. In this study, the acoustic nonlinearity parameters B/A of varied silicone oil samples （e.g., linear or hyper-branched） are experimentally measured by using a modified thermodynamic method. The results show that： （i） when the concentration of the silicone oil with a molecular weight of 5 × 10^4 increases from 0.5 g/100 ml to 8 g/100 ml, the corresponding B/A value increases by about 18%, but the acoustic velocity only increases by about 0.1%; （ii） when the molecular weight of the hyper-branched silicone oil is enhanced from 2 × 10^5 to 1 × 10^6, the B/A value increases by about 22%, while the acoustic velocity is only raised by about 0.2%. This study suggests that the B/A parameter of the silicone oil is more sensitive to the change in its molecular structure than that of the acoustic velocity. Thus, the B/A parameter might be utilized as an effective index for the development and optimization of the noninvasive imaging of the surgery of silicone oil tamponades.
基金support provided by the Ministry of Science and Technology,Taiwan,ROC under Contract No.MOST 110-2221-E-019-044.
文摘How to accelerate the convergence speed and avoid computing the inversion of a Jacobian matrix is important in the solution of nonlinear algebraic equations(NAEs).This paper develops an approach with a splitting-linearizing technique based on the nonlinear term to reduce the effect of the nonlinear terms.We decompose the nonlinear terms in the NAEs through a splitting parameter and then linearize the NAEs around the values at the previous step to a linear system.Through the maximal orthogonal projection concept,to minimize a merit function within a selected interval of splitting parameters,the optimal parameters can be quickly determined.In each step,a linear system is solved by the Gaussian elimination method,and the whole iteration procedure is convergent very fast.Several numerical tests show the high performance of the optimal split-linearization iterative method(OSLIM).
文摘鉴于调谐质量阻尼器(tuned mass damper,TMD)耗能结构在考虑土-结构相互作用(soil-structure interaction,SSI)时,随机地震响应分析方法较为复杂,本文提出一种计算响应谱矩和方差的简明解法,并深入研究SSI效应下结构随机地震动的响应特性。首先,根据达朗贝尔原理建立考虑SSI效应的TMD耗能结构的地震动方程,利用有限元动力技术建立基于实模态分解法的TMD耗能结构地震动一般方程;其次,利用功率谱二次式分解法推导出基于杜修力地震动激励的结构位移、TMD位移、基础平动和转动位移响应的0阶—2阶谱矩的简明封闭解;最后,通过算例,验证所提方法并研究了考虑SSI效应的TMD耗能结构地震响应特性。结果表明:在基础固定的情况下,场地土为中硬土、中软土和软弱土时,以层间位移为指标的动力可靠度、结构顶层位移逐渐变大,SSI效应逐渐显著;TMD在各种场地条件下都具有良好的减震效果,且最优参数受场地影响较小。与传统方法相比,本文方法计算过程更为简便,精度更高,能更高效地应用于实际工程。
