The Experts below are selected from a list of 31533 Experts worldwide ranked by ideXlab platform
Yang Zhong - One of the best experts on this subject based on the ideXlab platform.
-
New analytical free vibration solutions of orthotropic rectangular thin plates using generalized Integral Transformation
Journal of Computational and Applied Mathematics, 2020Co-Authors: Jinghui Zhang, Salamat Ullah, Yang ZhongAbstract:Abstract A first endeavor is made to obtain the analytical free vibration solutions of orthotropic rectangular thin plates utilizing the generalized Integral Transformation technique. Owing to the nature of the problem, it is very hard to get the exact solution of the title problem by common inverse/semi-inverse method. In solution procedure, the vibrating beam function is selected as the Integral core to form the generalized Integral Transformation pair. Then, the high order partial differential equation under specific boundary conditions is converted to linear algebraic equations and the exact solution is achieved in a straightforward way. One of the advantages of the proposed method is its simplicity and versatility and does not require pre-determining the deflection function which makes the solving procedure more reasonable. The method has wide applications range and can handle other elastic plate problems, such as shear buckling, buckling, and bending. The present results are validated by comparing with the existing analytical solutions which show satisfactory agreement.
-
Thermal stresses of flexible pavement with consideration of temperature-dependent material characteristics using stiffness matrix method
2011Co-Authors: Yang ZhongAbstract:The asphalt pavement is regarded as a multilayered elastic half space axisymmetrical body. By introducing the relationship between material characteristics and temperature into the fundamental equations of thermoelasticity and using mathematic methods of Laplace and Hankel Integral Transformation, the stiffness matrix for a layer is derived firstly. Then the global stiffness matrix is established for multilayered elastic half space using the finite element concepts in which layers are completely contacted. Therefore, explicit solution for thermal stresses of the asphalt pavement is obtained from the solution of the algebra equation formed by global stiffness matrix and the inverse Hankel and Laplace Integral Transformation. Because the elements of matrix do not include positive exponential function, the calculation is not overflowed. Therefore, the shortages of transfer matrix method are overcome. This approach serves as a better model for real pavement structure as it takes into account the relationships between the material characteristics and temperature in the pavement system.
-
Thermal stresses of flexible pavement with consideration of temperature-dependent material characteristics using stiffness matrix method
Mechanics of Time-Dependent Materials, 2010Co-Authors: Li-tao Geng, Rui-bo Ren, Yang ZhongAbstract:The asphalt pavement is regarded as a multilayered elastic half space axisymmetrical body. By introducing the relationship between material characteristics and temperature into the fundamental equations of thermoelasticity and using mathematic methods of Laplace and Hankel Integral Transformation, the stiffness matrix for a layer is derived firstly. Then the global stiffness matrix is established for multilayered elastic half space using the finite element concepts in which layers are completely contacted. Therefore, explicit solution for thermal stresses of the asphalt pavement is obtained from the solution of the algebra equation formed by global stiffness matrix and the inverse Hankel and Laplace Integral Transformation. Because the elements of matrix do not include positive exponential function, the calculation is not overflowed and the shortages of transfer matrix method are overcome. This approach serves as a better model for real pavement structure as it takes into account the relationships between the material characteristics and temperature in the pavement system.
Leslaw K Bieniasz - One of the best experts on this subject based on the ideXlab platform.
-
highly accurate inexpensive procedures for computing chronoamperometric current Integral Transformation kernel and related Integrals for an inlaid disk electrode
Electrochimica Acta, 2018Co-Authors: Leslaw K BieniaszAbstract:Abstract Recent theory of chronoamperometry at inlaid disk electrodes [L. K. Bieniasz, Electrochim. Acta 199 (2016) 1–11] provided a rigorous formula for the transient Faradaic current. However, numerical evaluation of the formula is costly and requires a multiprecision computing environment. In this work new procedures are developed for calculating the current and also the Integral Transformation kernel and related Integrals needed by the adaptive Huber method for solving electrochemical Volterra Integral equations. The procedures (implemented in C++) are computationally inexpensive (require less than a microsecond, of a contemporary processor time, per a single return value), but highly accurate (yield moduli of relative errors smaller than about 10 − 15 for the dimensionless time t ¯ ≥ 0.01 , and probably smaller than 10 − 13 for t ¯ 0.01 ). To achieve such a performance, new estimates of the coefficients of the small- t ¯ asymptotic current expansion are deduced, the coefficients of the large- t ¯ expansion are rederived with a high accuracy, and these expansions are combined with intermediate- t ¯ polynomial approximations resulting from minimax fittings to reference data. The consistency of all these procedures is tested by simulating chronoamperometry by the adaptive Huber method. The procedures can be useful for simulation, testing/validating of diverse modelling techniques, and for experimental data analysis.
-
a highly accurate inexpensive procedure for computing Integral Transformation kernel and its moment Integrals for cylindrical wire electrodes
Journal of Electroanalytical Chemistry, 2011Co-Authors: Leslaw K BieniaszAbstract:Abstract Cylindrical wire or fiber electrodes are attractive for electro-analytical applications, but the theory of transient methods at such electrodes is complicated, necessitating approximate expressions or procedures for computing various special functions occurring in the theory. One of such functions is the Integral Transformation kernel function corresponding to semi-infinite pure diffusion conditions. In the present work a highly accurate and computationally inexpensive procedure for computing the cylindrical contribution to this kernel function is presented. The procedure relies on local polynomial approximations covering the entire argument domain, and it provides at least 14–15 significant digits. The procedure also computes q th order moment Integrals of the kernel function (where q ⩾ 0 is a real number). The relative accuracy of 14–15 digits, of the moment Integrals, has been verified for q = 0, 1 and 2. The procedure can be used in conjunction with numerical algorithms for the solution of Integral equations or for the convolution analysis of experimental transients. It can also be used for the computation of chronopotentiometric responses to the programmed current density following the power-time dependence i ( t ) = i 0 t q with integer q ⩾ 0, which is shown as an example application.
R M Cotta - One of the best experts on this subject based on the ideXlab platform.
-
Conjugate Heat Transfer: Analysis Via Integral Transforms and Eigenvalue Problems
Journal of Engineering Physics and Thermophysics, 2020Co-Authors: D. C. Knupp, R M Cotta, C. P. Naveira-cottaAbstract:An Integral transform approach to the solution of the problem on conjugate heat transfer, combining the singledomain formulation with the convective eigenfunction expansion basis within the total Integral Transformation framework, which leads to a nonclassical eigenvalue problem, is presented. The problem on the conjugate heat transfer in the transient two-dimensional incompressible laminar flow of a Newtonian fluid in a parallel-plate channel is considered to illustrate the hybrid numerical-analytical approach. To demonstrate the improvement of the convergence rate achieved with the methodology proposed, a critical comparison against the traditional total Integral Transformation solution of the diffusive eigenvalue problem is provided, and results are presented and discussed for three representative situations realized with different Peclet numbers: Pe = 1, 10 and 100. A remarkable improvement of the convergence rate, obtained especially with the large Péclet numbers, offers evidence of the validity of the expansion constructed upon the nonclassical eigenvalue problem proposed.
-
conjugated heat transfer in complex channel substrate configurations hybrid solution with total Integral Transformation and single domain formulation
Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems, 2017Co-Authors: Jose Luiz Zanon Zotin, Diego Campos, R M CottaAbstract:Integral transforms have been extensively employed in the analysis of linear and nonlinear convection-diffusion problems, in light of the robust, precise and cost-effective hybrid numerical-analytical solutions that can be achieved in several different classes of problems in heat and fluid flow. In recent years, a single domain reformulation strategy has been introduced which, in combination with the Generalized Integral Transform Technique (GITT), allows for the straightforward handling of complex geometries, rewritten with space variable equation coefficients such as in heterogeneous media. This work further advances the solution of conjugated heat transfer problems for complex channel-substrate geometrical configurations through the GITT approach, here combining a single domain formulation and a total Integral Transformation scheme based on a multidimensional eigenvalue problem. An application is considered more closely to illustrate the approach for a two-dimensional geometry, consisting of a horseshoe-like microchannel within a rectangular substrate. The results presented demonstrate the adequacy of the solution methodology for the thermal analysis and design of thermal microsystems with complex shapes.
-
experimental identification of thermophysical properties in heterogeneous materials with Integral Transformation of temperature measurements from infrared thermography
Experimental Heat Transfer, 2013Co-Authors: Diego C Knupp, Carolina P Naveiracotta, Helcio R B Orlande, R M CottaAbstract:This work deals with the experimental estimation of spatially variable thermal conductivity and diffusivity in heterogeneous media, with temperature measurements obtained via infrared thermography being used in the inverse analysis. The direct problem solution for a one-dimensional heat conduction experiment is analytically obtained via Integral transforms, and the related eigenvalue problem is solved by the generalized Integral transform technique. The inverse problem is handled by Bayesian inference through a Markov chain Monte Carlo algorithm. The functional representation and estimation is based on the eigenfunction expansion of the thermal conductivity and diffusivity themselves, and the unknown parameters become the corresponding expansion coefficients. The inverse analysis is performed on the transformed experimental temperature field instead of employing the actual local temperature measurements, thus promoting a significant data reduction through the Integral Transformation of the experimental me...
-
Integral Transformation of the navier stokes equations in cylindrical geometry
Computational Mechanics, 1998Co-Authors: L M Pereira, J S Perezguerrero, R M CottaAbstract:The Generalized Integral Transform Technique (G.I.T.T.) is extended to handle the incompressible Navier-Stokes equations for two-dimensional steady laminar flow in cylindrical geometries. Hybrid numerical-analytical solutions with controlled accuracy are obtained, as a result of an appropriate choice of the associated eigenfunction expansion basis, extracted from the diffusion operator of the stream function-only formulation for this class of problems. The approach is illustrated for developing laminar flow within an annular channel and numerical results are obtained to demonstrate the excellent convergence characteristics of this hybrid method. Critical comparisons against the boundary layer formulation are provided, and a set of benchmark results is produced, for different values of Reynolds number and aspect ratio.
Y C Shiah - One of the best experts on this subject based on the ideXlab platform.
-
new domain Integral Transformation in boundary element analysis for 2d anisotropic thermoelasticity
Journal of Engineering Mechanics-asce, 2016Co-Authors: Y C Shiah, Sheng Hung WangAbstract:AbstractAs is well known in the boundary element method (BEM), thermal effect reveals itself as an additional volume Integral in the associated boundary Integral equation. Any attempt to directly integrate it shall require domain discretization that will destroy the BEM’s most distinctive notion of boundary discretization. For anisotropic elastostatics, this additional volume Integral can be exactly transformed onto the boundary; however, additional line Integrals intersecting the domain are invoked in such a Transformation. For simply connected domains, evaluation of the extra line Integrals can be avoided by simply employing branch-cut redefinitions; however, the evaluation is inevitable for multiply connected domains. This paper presents a new approach to validate the exact Transformation yet without invoking extra line Integrals. For the two-dimensional thermoelastic analysis of anisotropic bodies, the present approach has completely restored the BEM’s feature of boundary discretization without extra ...
-
the solution to an elliptic partial differential equation for facilitating exact volume Integral Transformation in the 3d bem analysis
Engineering Analysis With Boundary Elements, 2015Co-Authors: Y C ShiahAbstract:Abstract In the direct boundary element method (BEM), the body-force or its equivalence will reveal itself as a volume Integral that shall destroy the important notion of boundary discretisation. For resolving this issue, the most elegant approach would be to analytically transform the volume Integral to boundary ones. In the process of such attempt for 3D anisotropic elastostatics, the key lies in analytically formulating the fundamental solution to a partial differential equation. In this paper, the partial differential equation is presented in an elliptic form, followed by formulating its analytical solution. In the BEM analysis, the formulated solution will be a key part to the success of performing exact volume-to-surface Integral Transformation.
-
direct volume to surface Integral Transformation for 2d bem analysis of anisotropic thermoelasticity
Cmes-computer Modeling in Engineering & Sciences, 2014Co-Authors: Y C Shiah, M H Aliabadi, Chyanbin HwuAbstract:As has been well documented for the boundary element method (BEM), a volume Integral is present in the Integral equation for thermoelastic analysis. Any attempt to directly integrate the Integral shall inevitably involve internal discretisation that will destroy the BEM's notion as a true boundary solution technique. Among the schemes to overcome this difficulty, the exact Transformation approach is the most elegant since neither further approximation nor internal treatments are involved. Such Transformation for 2D anisotropic thermoelasticity has been achieved by Shiah and Tan [1] with the aid of domain mapping. This paper revisits this problem and presents a modified Transformation process for 2D anisotropic thermoelasticity, where no domain distortion is involved. Being defined in the original Cartesian coordinate system, the volume Integral is analytically transformed to the boundary, being derived using the Stroh formulism. This Transformation is favorable especially when the corresponding anisotropic field is directly calculated using the anisotropic Green's function without resorting to domain mapping. At the end, numerical examples are provided to show the validity of such Transformation.
-
exact boundary Integral Transformation of the thermoelastic domain Integral in bem for general 2d anisotropic elasticity
Computational Mechanics, 1999Co-Authors: Y C Shiah, C L TanAbstract:In the direct formulation of the boundary element method, body-force and thermal loads manifest themselves as additional volume Integral terms in the boundary Integral equation. The exact Transformation of the volume Integral associated with body-force loading into surface ones for two-dimensional elastostatics in general anisotropy, has only very recently been achieved. This paper extends the work to treat two-dimensional thermoelastic problems which, unlike in isotropic elasticity, pose additional complications in the formulation. The success of the exact volume-to-surface Integral Transformation and its implementation is illustrated with three examples. The present study restores the application of BEM to two-dimensional anisotropic elastostatics as a truly boundary solution technique even when thermal effects are involved.
L.d. Gusarevich - One of the best experts on this subject based on the ideXlab platform.
-
On the non-convolution Transformation with the Macdonald type kernel function
Fractional Calculus and Applied Analysis, 1998Co-Authors: S.b. Yakubovich, L.d. GusarevichAbstract:Integral Transformation, involving a Macdonald type function in the kernel, is considered in this paper. Some L2-properties, relationship with the Hilbert and the Kontorovich-Lebedev transforms, the Parseval equality and inversion theorem are established.