In this paper we present a new data structure which gives a steering capability to a computer-assisted scientific-simulation environment or a problem solving environment (PSE) for partial-differential-equations (PDEs)-based problems. One of the important key issues in PSE researches is a steering capability including the interaction between a PSE and a user. In order to tackle this key issue, the new data structure is proposed to introduce the process steering capability to the PSE. The data structure is used to describe PDEs, boundary conditions, the initial conditions, all processes including PDE discretization, equation manipulation and program generation, and a generated program flow. In the data structure each PDE, each term, each symbol, each process and each component of the generated program flow have their meanings, which are linked and referred by pointers. We apply the data structure to a PDEs PSE called NCAS system. Based on the proposed data structure, the steering capability is realized, and the PSE communicates with the user smoothly and flexibly through an interactive visual interface.

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A problem solving environment(PSE) is a computer software system or a computational facility to solve, for example, partial-differential-equations(PDEs) -based problems. Solving PDEs problems in a PSE requires smooth and flexible interactions between a PSE and a user. We have developed a PSE for PDEs problems called NCAS system. NCAS tracks the process of problem solving task, and allows the user to visualize and modify/steer the program generation process at any point. So far several PSEs for PDEs problems have been developed. Most of them do not allow users to visualize and/or to modify the process of program generation. The capabilities of visualization and steering allow the users to understand the whole process well. The capabilities of process visualization and steering are essentially important to steer a problem solving process to an appropriate direction. The effective visualization and steering of the problem solving process in NCAS are demonstrated in this paper.

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The finite element method (FEM) is an effective technique in the numerical analysis for solving partial differential equations. However, since the mesh subdivision has become a very burdensome process, applications of meshless or element-free methods, which require only nodal data, are desired to the analysis systems. In this paper, an overview of the newly developed element-free analysis prototype system, intended for the elasticity problems in two dimensions, and some of its tools are given. Since the system is based on the element-free Galerkin method (EFGM), which is a kind of meshless method, grid and mesh partitioning is totally unnecessary. A tool to create and record the nodal data, which will be introduced later in the passage, is something unique to this system. In order to simplify the tasks necessary to run an analysis, the authors created a paintbrush tool for the prototype system on the Apple Macintosh to “draw” or “paint” such data onto the defined domain.

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This paper describes an integrated and automated computer aided engineering (CAE) system for multidisciplinary design and its interface in the Internet. The CAE system is based on an object oriented approach, allows fully automated finite element (FE) analyses of various physical/mechanical phenomena, and facilitates an employment of existing software. The system operates in a distributed computer environment. An advanced interface for the system is also developed using VRML Ver.2.0 and JAVA. A user can easily access to the system from anywhere in the world through the Internet using a WWW browser, and manipulate analysis results lively under a multi-display environment. The CAE system and its interface were successfully applied to the shape design of a novel microaccelerometer based on a tunneling current concept.

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