International Journal of Computational Engineering Science

Engineering projects are increasingly becoming more complex and have to be carried out in close cooperation among several experts from different disciplines and locations. This has resulted from a rapid progress in communication, computing, visualization, and storage technology. Research and applications of distributed computing, visualization and networked collaboration, therefore, is becoming an important subject. We present three ongoing distributed collaborative systems at the National Center for High-performance Computing in Taiwan: (1) A collaborative visualization environment which supports distributed and interactive visualization and collaboration in the three-dimensional virtual world, (2) A collaborative web browser system that creates an HTML document shared environment for supporting remote conferencing, and (3) An Internet-based distributed analysis environment that is designed for distributed simulation and visualization. We have explored and examined various computer tools and communication technologies for the development of the networked collaborative systems. Our endeavor sheds some light on the future development and applications of an efficient networked collaborative infrastructure which supports distributed computing, presentation and visualization, data and information management, documentation, and conferencing.

In this paper we approach the convergence question of the dynamic modes computed in solids by the finite element method. The complete solid elements that we consider are obtained by adding hierarchical degrees of freedom to the standard complete elements with linear strain interpolation; that is, the six-node triangle and the ten-node tetrahedron, If these elements are formulated in energy orthogonal form, there exist a property that could be used as an error indicator to decide if a set of dynamic modes is accepted or not.

This paper presents a new robust, two -phase hybrid optimization algorithm to solve non-linear constrained optimization problems. The proposed algorithm is very much useful when addressing heavily constrained optimization problem in terms of solution accuracy and computation time. It can out perform conventional genetic algorithms (CGAs) is the sense that Hybrid GAs makes it possible to improve both the quality of the solution and reduce the computing expenses. The proposed hybrid scheme is developed in such a way that a simple real coded GA is acting as a base level search, which makes a quick decision to direct the search towards the optimal region, and local search method is next employed to do fine tuning. The phase - 1 uses real coded genetic algorithm, while optimization by direct search and systematic reduction of the size of search region method is employed in the phase - 2. Thirteen test problems were taken from the literature have been simulated and results obtained were compared. The results clearly demonstrate that the proposed hybrid real coded genetic algorithm not only improve the reliability but also make the algorithm more efficient in terms of number of function evaluations to reach the global optimum point. Thus the usefulness and effectiveness of this algorithm is placed in a sharper focus.

The present paper aims to explore an alternatice interpolation strategy for the assumed displacement fields in the finite element buckling analysis of straigth and curved composite beams. The elemental static equilibrium equations are employed to derive the alternate interpolation polynomials for the displacement fields. These polynomials are coupled by means of coefficients involving the generalized co-ordinates and geometrical and material properties of the element. The proposed interpolation scheme lead to an element, which is free from spurious constraints in the Euler's limit of slender beam behaviour, that is in-extensible bending, and hence exhibits no locking. The 2-node beam element having six engineering degrees of freedom per node is developed using this coupled displacement field. The accuracy and convergence characteristics of the element are shown to be independent of material lay-up and slenderness ratio. To establish the consistent performance of the element, several test problems over a wide range of slenderness ratio with straigth-to-deep arch configurations of isotropic/composite materials are considered.

This paper presents a nonlinear finite element procedure for the simulation of the hysteresis behavior and the shape memory effect of shape memory alloy (SMA) materials. The consitutive equation is based on the consistent mathematical description of martensite fraction evolution during the thermoelastic phase transformation in shape memory alloys induced by general thermomechanical loading. The kinematics law is based on an experimentally defined stress-temperature phase diagram, transformation functions for one-dimensional SMA body, and a novel vector hysteresis temperature phase diagram for an initial value of martensite fraction. The solution of the geometrically and physically nonlinear problem is achieved by application of Newton's iteration method. Numerical results which consider the temperature and pseudoelastic effects show that the proposed procedure is an effective computational tool for the simulation of a broad range of shape memory material based applications.

This paper presents the identification and the control of a semi-batch reactor. The process is described by a parametric Volterra model. The control strategy uses a nonlinear model based predictive control law. A practical procedure for the simultaneous estimation of the states and the unknown process parameters is developed. The proposed control action is obtained by solving a fourth order non-linear programming problem on-line subject to contraints on the input and output signals. The control strategy is obtained augmenting the non-adaptive controller with an indirect Weighted Recursive Prediction Error Method, which accounts for unknown and/or slowly time-varying parameter and immeasurable states. The developed control strategy has been evaluated experimentally. The obtained results have been reported and discussed.

This paper presents a development of the p-version hierarchical interpolation functions in one, two three and higher dimensions. The interpolation functions may be used, for example, in obtaining strong solutions of differential equations. The concepts are presented first through the derivation of the Cⁱ-functions in one dimension. Then the one-dimensional functions are used to derive the interpolation functions in two, three and higher dimensions. It is demonstrated that for rectangular finite elements the concepts presented herein allow the construction of any order hierarchical interpolation functions in one, two, three and higher dimensions. The necessary and sufficient conditions that must be satisfied by higher order continuity interpolation functions are presented. Theorems that insure that the proposed procedure of generating the higher order continuity interpolation functions are also presented. With this approach of constructing interpolations it is indeed possible to generate finite element interpolation functions with inter-element continuity in agreement with the strong solutions, which eliminate the need for the weak forms of differential equations.