Computer-aided Design Methodology Research Articles

Computer-aided design of magnetizing fixtures for the post-assembly magnetization of rare-earth permanent magnet brushless DC motors

A computer-aided design (CAD) methodology for the design of post-assembly impulse magnetizing fixtures for radial-field brushless DC motors is presented. The design methodology has been applied to an air-cored fixture for the post-assembly magnetization of a four-pole external rotor brushless DC motor. Its rotor is constructed from a stack of sintered radially anisotropic NdFeB ring magnets/ss and a solid mild steel core which will tend to act as a short-circuit to the applied magnetizing field and have induced eddy currents which inhibit the penetration of the magnetizing field into the magnet. The post-assembly magnetization of a three-phase brushless DC motor with an exterior rotor equipped with sintered NdFeB magnets has been shown to be feasible, albeit resulting in a slight decrease in performance compared to a motor constructed from premagnetized magnets. However, the post-assembly magnetization of interior rotor topologies is considerably more demanding. Nevertheless, the CAD facility for the design of post-assembly magnetization fixtures has been shown to agree well with results from the practical fixture considered. >

Use of expert systems in the design of thermal equipment and processes

A study has been carried out on the use of knowledge-based computer-aided design methodology for the design of thermal systems. An expert system is developed using a Prolog-based front end, where the design rules, material databases, computational procedures, and the relevant expert knowledge are implemented. A combination of quantitative and heuristic inputs are employed in the design process. The basic approach employs an iterative redesign strategy, starting with an initial design obtained from the available knowledge base, and the design parameters are iteratively varied until the specified design rules and constraints are satisfied. The general approach can be employed for a variety of thermal systems. The application to a practical system is demonstrated by the design of an electrical furnace used in the thermal processing of materials. The results from the numerical simulation and design of this system are presented to indicate the basic features and the versatility of the expert system.

An integrated approach to three-dimensional information management with MACCS-3D

In the past decade, the scientific community has realized the value of three-dimensional (3D) structural information and '3D searching' has started to become an important new methodology for computer-aided drug design. During this time, molecular modeling information generated from various sources has proliferated due to the growing availability of software and hardware and the increasing use of crystallographic and spectroscopic techniques. This information needs to be organized to allow for its effective storage and retrieval. This paper presents an approach to address this problem with a recently introduced program, MACCS-3D. In particular, this approach utilizes MACCS-3D's capability of handling data specific for atoms and atom pairs. With this software, various biological, computational, and spectroscopic data can be merged, allowing scientists from different disciplines to access and use this information more efficiently.

Multiobjective intelligent computer-aided design

A methodology for multiobjective intelligent computer-aided design (MICAD) of large-scale systems is proposed. The proposed MICAD methodology partitions the knowledge base required for the design system to include a progressively acquired preferential component captured using a decision theoretic model and an a priori acquired operational component that can be represented using a wide range of artificial intelligence and expert systems techniques. User preferences are employed to personalize the search for improved designs and dynamic acquisition of those preferences enables the systems, to some extent, to mimic and conform to different users, decision-making styles, and design goals. The primary emphasis is the decision theoretic treatment of user preference in a general search strategy and design domain. The construction of the operational knowledge base is demonstrated to be an opportunity for application of existing artificial intelligence techniques.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Computerized design and manufacturing of plate cams

Abstract Cams are essential mechanical parts in manufacturing industries. Traditional methods of cam design and production are time-consuming and error-prone. This paper is an effort to try to develop a methodology of computer-aided design and manufacturing of plate cams. The computerized procedure is detailed with accompanying examples.

Design work with the support of an expert system

This paper deals with the mechanical design of systems obtained with the assistance of the computer. Whereas the use of CAD (computer-aided design) methodologies has become an integral part of the operator's fundamental expertise in traditional mechanical design work, the use of artificial intelligence logics and methodologies is still under development. Some possibilities will be examined here which are offered by an expert system shell used on a personal computer with 512 K memory. The expert system has been developed and applied so as to summarise the design experience of the authors and to transform the logical conditions they have examined and highlighted into the expert system's constituent elements. The application has focused on the design of mechanical transmission systems. The special case of mechanical transmission with belts, chains, gears, clutch wheels, cables, etc., has highlighted the support which an expert system can provide to assist the designer.

An automated software design assistant

An automated software design assistant was implemented as a part of a long-term project with the objectives of applying the computer-aided technique to the tools in a software engineering environment. A set of quantitative measures are derived based on the degree to which a particular design satisfied the attributes associated with a structured software design. The measure are then used as decision rules for a computer-aided methodology for structured design. The feasibility of the approach is also demonstrated by a case study using a small application system design problem.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Methodology for Large-Scale Process Control System Design

This paper reviews the development and application of a specific computer-aided design methodology called “SIMKON” for large-scale dynamic process control systems. This methodology has been implemented in the SIMKON-IV software system. The set of algorithms used in SIMKON is based on state-of-the-art simulation and control technologies and is a spinoff from the well-known DIGIKON-IV, ADAPS and KONPACT programs developed for aerospace and defense applications by Honeywell over a period of time and includes about 50,000 FORTRAN-IV statements. The significance of this development is that it provides the user with the total system capability of developing alternative controller organizations and corresponding multiperformance figures for large systems under one unified interactive command structure. The interactivity with the user significantly improves the productivity of the user. The richness of its command repertoire and the advanced algorithms it uses for implementing its functions make SIMKON-IV one of the most complete and advanced system engineering tools for control applications in the process industry. Brief descriptions of this tool and its basic capabilities and application areas are given. In addition, typical inputs and outputs are illustrated.

Custom design of a VLSI PCM-FDM transmultiplexer from system specifications to circuit layout using a computer-aided design system

The computer-aided design of a VLSI PCM-FDM transmultiplexer is presented. The entire design process from system specifications to integrated circuit layout is carried out with the aid of specialized computer programs for analysis, synthesis and optimization at each design level: the filter network, the architecture and the circuit layout. These CAD tools support a top-down custom design methodology based on bit-serial architectures and standard cells. A customized architecture is constructed, which is integrated using a 5- <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">\mu</tex> m CMOS cell library. The results are compared with a fully manual design and demonstrate the power of architecture based computer-aided design methodologies for VLSI filtering. By combining both synthesis as well as optimization aids at each design level, it is possible to achieve a high degree of automation while retaining an efficient use of silicon area, high throughput and moderate power consumption.

Custom design of a VLSI PCM-FDM transmultiplexer from system specifications to circuit layout using a computer-aided design system

The computer-aided design of a VLSI PCM-FDM transmultiplexer is presented. The entire design process, from system specifications to integrated circuit layout, is carried out with the aid of specialized computer programs for the analysis, synthesis, and optimization at each design level: the filter network, the architecture, and the circuit layout. These CAD tools support a top-down custom design methodology based on bit-serial architectures and standard cells. A customized architecture is constructed which is integrated using a 5-/spl mu/m CMOS cell library. The results are compared with a fully manual design and demonstrate the power of architecture based computer-aided design methodologies for VLSI filtering. By combining both synthesis and optimization aids at each design level it is possible to achieve a high degree of automation while retaining an efficient use of silicon area, high throughput, and moderate power consumption.

Technology transfer between VLSI design and software engineering: CAD tools and design methodologies

Recent research on the explicit transfer of technology used in computer-aided design (CAD) tools and design methodologies is reported. First, several examples are given of applications of these technologies to software engineering. Then, three research projects are described which focused on applying software engineering principles to the VLSI design process. They are: a methodology, language, and assessment tool for multilevel mixed-mode VLSI designs; a research project that explored the potential for transfer of software design methodologies for managing VLSI design complexity; and a specification technique for modules in a VLSI design that localizes the impact of changes to the design. Next, a CAD tool and design methodology are described which consider the design of software and hardware together, and apply common techniques to both. Finally, some observations are made on the appropriateness of technology transfer between VLSI design and software engineering.

Molecular dynamics and minimum energy conformations of GnRH and analogs. A methodology for computer-aided drug design.

Molecular dynamics and minimum energy conformations of GnRH and analogs. A methodology for computer-aided drug design.

Computer-Aided Design of Fractional Factorial Experiments Given A List of Feasible Observations

Abstract When attributes of experimental units serve as independent variables, locating the units possessing the required combinations of attribute values for an experimental design can be a serious practical problem. Often, however, data sets of observable experimental units exist. A computer-aided design methodology is presented which determines which two-level factorial and orthogonal fractional factorial designs are feasible, given the data set of observable experimental units. Contrary to usual practice, the number of factors to consider is an explicit experiment planning variable in the methodology. All combinations of ten and fewer factors and 210 and fewer observations (in steps of powers of 2) are represented by a feasibility matrix. For a given set of observable experimental units, the design methodology attempts to map which cells of the matrix are feasible. Dependency relationships among feasibility matrix cells are stated which allow implicit enumeration of cells. An example taken from highwa...

A computer-aided methodology for conceptual data-base design

In this paper we describe an integrated system to aid data-base conceptual design. In this system, incremental enrichments of the conceptual description of user requirements both with a top-down and a bottom-up discipline are allowed. Such enrichments involve both data and transactions. Data enrichments can be expressed by a disciplined set of design primitives. For every primitive any inconsistencies arising are described and a set of scenarios to eliminate them is suggested. Transaction enrichments are expressed in terms of declarations which define these transactions at various conceptual refinement levels. Such declarations can be compared to the partial conceptual schema obtained by data enrichments and possible incompleteness and inconsistency situations arising are described. Future developments of the research program are also outlined.

Computer aided operability analysis via interactive graphics

A comprehensive computer-aided design methodology utilizing the highly interactive capabilities between a graphics computer and the user is described. The program, CHESOPS, enables a flexible simulation of any arbitrary chemical process by synthesizing the process design about several steady state values and extending the analysis to the effects of design changes on process operability. In this way the process may be visualized within a dynamic environment from which interactive control system design and dynamic simulation takes place. The highly flexible nature of the program enables efficient and comprehensive investigation of alternative designs, control structures, and optimal operating conditions.