FEMLIB: An Object-Oriented Framework for Optimization and Simulation

In this paper we discuss the design of an object-oriented framework for simulation and optimization. Although oriented around high-level problem solving, the framework defines several classes of problems and includes concrete implementations of common algorithms for solving these problems. Simulations are run by combining these algorithms, as needed, for a particular problem. Included in this framework is the capability to compute the sensitivity of simulation results to the different simulation parameters (e.g. material properties, boundary conditions, etc). This sensitivity information is valuable in performing optimization because it allows the use of gradient-based optimization algorithms. Also included in the system are many useful abstractions and implementations related to the finite element method.

Virtual Assembly Design Environment

Virtual reality is a technology which is often regarded as a natural extension to 3D computer graphics with advanced input and output devices. This technology has only recently matured enough to warrant serious engineering applications. The integration of this new technology with software systems for engineering, design and manufacturing will provide a new boost to the field of computer-aided engineering. One aspect of design and manufacturing which may be significantly affected by virtual reality is design for assembly. This paper presents the ideas behind a current research effort aimed at creating a virtual assembly design environment and integrating that environment with a commercial, parametric CAD system.

A Boundary Element Method for Multi-Body Contact Problems and its Application to the Analysis of a Huge Excavator

The derivation of a boundary integral formulation and discretization technique in terms of boundary elements for the solution of multi-body contact problems has been carried out. A FORTRAN program has been developed based on this boundary element formulation and has been applied to the stress analysis of a huge caterpillar excavator woth 16 m3 bucket capacity.

Sharper Labyrinth Seal Edges to Allow Greater Clearance Without Increased Leakage

A numerical study was undertaken to examine the effects of utilizing sharper edges for increasing the leakage resistance of advanced labyrinth seal configurations. Such an increase allows the designer to enlarge the extremely small knife clearance, providing a seal with less damage susceptibility at the same leakage rate. The maximum possible leakage resistance increase from changing three cavity edges to perfectly sharp ones was estimated from the present computations. In addition, previous measurements of the edge sharpness effect on the leakage through orifices are appropriately utilized to obtain a rough estimate of the resistance increase for generic seals. The latter allows consideration of a broader range of application. Further, turbulence energy generation contours reveal that only one particular cavity edge needs to be sharpened in order to obtain a significantly increased leakage resistance.

Variable Focus Three-Dimensional Laser Digitizing System

This paper describes a new three-dimensional scanning technology which is being developed at Colorado State University. Unlike other laser-based scanners which use active or passive triangulation to obtain surface range data, the new variable focus laser digitizing system (VFLDS) uses the principles of optical focal length to measure surface range data. This system should represent a significant step forward in speed and simplicity over current laser-based single point digitizing systems while retaining all of their advantages. The goal of the initial research presented here is to produce preliminary results which will prove the viability of this new approach.

A Hybrid Fuzzy Controller for Industrial Power Plants

The automation of the control to a power plant is indeed a challenge mainly because of the occurrences of random and unpredictable variations in output demands as well as because of highly non-linear behavior of the system itself [1]. It is sometimes argued that the ‘best’ control for a power plant is the operators themselves. Experienced operators are capable of taking decisions on the basis of incomplete and imprecise information. The extent to which these decisions are correct is a matter of speculation. Erroneous conclusions, established post facto, are chalked up to the learning process and in fact, contribute to the forming of a good, experienced control team. The need to automate the control process for a plant is even more acutely felt when considering the complexity of the plants themselves and the volume of data that would have to be processed before a control decision can be taken. Factored into this decision would also be several governing parameters such as costs, reliability, other constraints and their interdependancy, as well as planned and unscheduled outages for maintenance and so on. In this paper, however, only one facet of a power plant operation is considered. It is intended to demonstrate that thermal efficiency may be improved by better techniques for automated control of throttle valves in the steam turbine of the plant. One of these options, fuzzy logic, is selected, and defended, as being the more effective than current techniques. A comparative analysis is conducted of control techniques for plant operations followed by a brief overview of fuzzy control and its application to control of non-linear systems. A method of applying this ‘new’ computer-based technique to control of non-linear, somewhat erratic plants is presented and discussed.

The Significance of Specifications in the Product Development Processes

An approach to support the appropriate definition, formulation and presentation of requirements obeying the needs of the employees is being presented. Classifiying the needs for information of the employees according to some characteristics, a guideline for how to promote the information needed by them can be developed. The goal is to ensure that everyone involved in the process — even the subcontractor — has the right information available in the right form at the right time. Defining requirements lists, splitting them into partial requirements lists for each area of the company, each process phase or each team, and then formulating these requirements and presenting them in an adequate way is the proceeding strived for. The result will be implemented into an information infrastructure to support the product development process continuously.

A Unifying Version Model for Object-Oriented Engineering Database

Versioning has been one of the important requirements for engineering design databases and is of increasing interest to database system designers. While there exist many object-oriented DBMS’s that support various versioning facilities, these systems consider the versioning problems as two separate domains: object versioning and schema versioning. In this paper, we consider both domains together and propose a unifying version model for both objects and schema. In particular, we present how we unify version controls for schema and objects, and describe issues in implementation.

COVIRDS: A Conceptual Virtual Design System

This paper describes the development of a computer system architecture for mechanical conceptual shape design within a virtual environment — COVIRDS1 (COnceptual VIRtual Design System).

Maximal Volume Decomposition and its Application to Feature Recognition

A method has been developed that decomposes an object having both planar and curved faces into volumes, called maximal volumes, using the halfspaces of the object. A maximal volume has as few concave edges as possible without introducing additional halfspaces. The object is first decomposed into minimal cells by extending the faces of the object. These minimal cells are then composed to form maximal volumes. The combinations of such minimal cells that result in maximal volumes are searched efficiently by examining the relationships among those minimal cells. With this decomposition method, a delta volume, which is the volume difference between the raw material and the finished part, is decomposed into maximal volumes. By subtracting maximal volumes from each other in different orders and applying graph matching to the resulting volumes, multiple interpretations of features can be generated.