Clive L. Dym

Propagation of Ground Vibration: A Review

A review of the current state of the art of ground vibration propagation is presented herein. First the theoretical models of vibration attenuation are reviewed and then measurement techniques are discussed. Finally, measurement and theory are combined into predictive models, whose validity is discussed.

EXPERT SYSTEMS: New approaches to computer-aided engineering

This paper provides an overview of the burgeoning new field of expert (knowledge-based) systems. This survey, is tutorial in nature, intended to convey thegestalt of such systems to engineers who are newly exposed to the field. The discussion includes definitions, basic concepts, expert system architecture, descriptions of some of the programming tools and environments with which knowledge-based systems can be built, and approaches to knowledge acquisition. Some currently extant expert systems are describeden passant, including a few developed for engineering purposes. Comments follow on the engineering of knowledge, as both cultural and social processes. The paper closes with an assessment of the roles that expert systems can play in engineering analysis, design, planning, and education.

A knowledge-based system for automated architectural code checking

Abstract Recent efforts to develop a knowledge-based expert system capable of reviewing an architectural design for conformance with the Life Safety Code (LSC) of the National Fire Protection Association are described. These efforts include the specification of a frame-based representation of floor-plans and the development of a rule-based representation of LSC requirements. The representation was developed to operate on top of a geometrical database contained in a CADD system, within which the expert system will be embedded. That part of the LSC relating to egress requirements and fire protection in hospitals was selected as the particular domain for this prototype. The work reported has implications for the representation of architectural information in the context of computer-aided design, as well as for the representation of legally mandated code requirements.

Transmission loss optimization in acoustic sandwich panels

Considering the sound transmission loss (TL) of a sandwich panel as the single objective, different optimization techniques are examined and a sophisticated computer program is used to find the optimum TL. Also, for one of the possible case studies such as core optimization, closed‐form expressions are given between TL and the core‐design variables for different sets of skins. The significance of these functional relationships lies in the fact that the panel designer can bypass the necessity of using a sophisticated software package in order to assess explicitly the dependence of the TL on core thickness and density.

Toward the integration of knowledge for engineering modeling and computation

Recent developments in computer science, especially in the area of artificial intelligence (AI), have made possible the representation of knowledge in symbolic terms. This, in turn, has made it possible to represent and integrate a broader range of engineering knowledge so as to provide new kinds of computer support for both analysis and design. This paper presents a typology of engineering knowledge to provide a conceptual basis for its computational integration. A review of the roles of numerical, geometric, and symbolic representations is also given within the context of the knowledge typology. Illustrations are provided from the domain of structural engineering.

TRANSMISSION LOSS OF DAMPED ASYMMETRIC SANDWICH PANELS WITH ORTHOTROPIC CORES

Abstract A theoretical model of the acoustic performance of asymmetric sandwich panels is developed and verified by comparison with experimental data. The panel models consist of unequal elastic isotropic skins sandwiching an elastic orthotropic core. Damping is incorporated in both the skins and the core. The roles of various structural and material properties are determined via a parametric study. The importance of phase wave speeds and panel impedances for physically symmetric panels is discussed, as are implications for transmission loss characterization. For asymmetric panels it is seen that a relatively thick skin on one side produces some change in the transmission loss.

Stress and Displacement Estimates for Arches

This paper presents analytical estimates of the behavior exhibited by curved, archlike structures under radially directed and gravitational line loads. The behavior is shown to range from elementary beam bending at one end to a state of pure compression at the other, and its behavior can be tracked by an arch rise parameter that is a function of the arch’s semivertex angle, radius and thickness. The principal results are useful estimates of the dependence of the major displacements and stress resultants on the arch rise parameter. The results also offer some insight into the assumptions underlying Robert Maillart’s arch designs.

Issues in the Design and Implementation of Expert Systems

This article discusses the issues that arise in the design and implementation of expert systems. These issues include: task selection; the stages of development of expert system projects; knowledge acquisition; languages and tools; development and run-time environments; and organizational and institutional issues. The article closes with some speculation about the future development of expert systems.

MODELING AND INFORMATION IN THE DESIGN PROCESS

This paper examines how models and information are used in engineering, and especially in the engineering design process. Model use and information content are both important and strongly coupled, if only because models are used to develop information upon which basis engineering decisions are made and outcomes achieved. Classical decision theory suggests that the quality of a decision-making process is independent of the outcome, and yet models are used to obtain the best information possible in order to achieve the best outcome. This paper considers definitions of models, the implications of the information content of engineering models, and the role(s) models play in design decision making. It is suggested that a taxonomy of design models may be useful to the extent that it connects to both the type and quality of information it imparts, and to the quality of the outcome desired. The type of model is important for self-evident reasons; the quality of information is also important because design models must be predictive in ways that enable design. The quality of the outcome is important since that is the underlying point of a design process.Copyright

Representation and Problem-Solving: The Foundations of Engineering Design

Engineering design, a discipline of vital importance to US industry, is often perceived as lacking rigor and structure. An operational definition of engineering design is offered, to stress that representation is the key element in design. Recent developments in the field of artificial intelligence (AI) provide new techniques for design representation that enable better explication of design concepts. Further, the increased power and the flexibility of Al-based, computer-aided design tools offer opportunities for automating routine design and for creating designers assistants to support the exploration of design alternatives.