A numerical solution of an inverse parabolic problem with unknown boundary conditions

2007 ◽  
Vol 189 (1) ◽  
pp. 228-234 ◽  
Author(s):  
M. Ebrahimian ◽  
R. Pourgholi ◽  
M. Emamjome ◽  
P. Reihani
2002 ◽  
Vol 124 (4) ◽  
pp. 601-608 ◽  
Author(s):  
Jiin-Hong Lin ◽  
Cha’o-Kuang Chen ◽  
Yue-Tzu Yang

A two-dimensional inverse analysis utilizes a different perspective to simultaneously estimate the center and surface thermal behavior of a heated cylinder normal to a turbulent air stream. A finite-difference method is used to discretize the governing equations and then a linear inverse model is constructed to identify the unknown boundary conditions. The present approach is to rearrange the matrix forms of the governing differential equations and estimate the unknown boundary conditions of the heated cylinder. Then, the linear least-squares-error method is adopted to find the solutions. The results show that only a few measuring points inside the cylinder are needed to estimate the unknown quantities of the thermal boundary behavior, even when measurement errors are considered. In contrast to the traditional approach, the advantages of this method are that no prior information is needed on the functional form of the unknown quantities, no initial guesses are required, no iterations in the calculating process are necessary, and the inverse problem can be solved in a linear domain. Furthermore, the existence and uniqueness of the solutions can easily be identified.


2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Wen-Yu He ◽  
Fan-Cheng Meng ◽  
Wei-Xin Ren

AbstractCable force estimation is essential for security assessment of cable-stayed bridges. Cable force estimation methods based on the relationship between cable force and frequency have been extensively studied and used during both construction phase and service phase. However, the effect induced by inclination angle of the cable is not included in the establishment of frequency-cable force relationship as horizontal cable model is normally employed. This study aims to investigate the influence of the inclination angle on vibration based cable force estimation and provide practical formulas accordingly. Firstly numerical examples of fixed-fixed and hinged-hinged cables are simulated to illustrate the necessity of considering the inclination angle effect on the modal parameters and cable force estimation for inclined cables with small sag. Then practical formulas considering the inclination angle effect to estimate the cable force of fixed-fixed and hinged-hinged cables via the fundamental frequency are established accordingly. For the inclined cables with unknown boundary conditions, the coefficients reflecting boundary condition are predicted via the practical formulas for fixed-fixed and hinged-hinged cables. And the cable force considering the influence of inclination angle and unknown boundary conditions is obtained by iteration method. Finally, numerical examples are presented to demonstrate the effectiveness of the proposed method.


2014 ◽  
Vol 06 (02) ◽  
pp. 1450014 ◽  
Author(s):  
S. KHAJEHPOUR ◽  
M. R. HEMATIYAN

A stable technique based on the finite element method for inverse analysis of coupled nonlinear thermo-elastic problems is presented. Not only the time-domain is divided into small intervals, but also the space-domain is divided into several sub-domains. The inverse problem is solved in each sub-domain subsequently. For the inverse analysis in each sub-domain, the unknown boundary conditions are found by using an optimization method and also by employing the information obtained in the previous sub-domain. The method is sufficiently stable to be used for inverse analysis of a thermo-elastic problem under a thermal shock. Three numerical examples are provided to demonstrate the efficiency of the proposed method. The effects of the number of sub-domains are investigated in the examples.


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