摘要:

Engineering design essentially consists of generating specifications for the artifact being designed. It involves complex tasks of generating various feasible solutions and critically evaluating them. Developing knowledge-based systems (KBSs) requires adopting proper knowledge organization, representation schemes and suitable problem-solving techniques, which depend on the nature of the design task and type of knowledge involved. This paper presents one such exercise carried out in the domain of bridge engineering design. A design process model, comprising of rule-based inference, solution generation (synthesis) and evaluation (criticism) tools, is proposed based on the methodologies adopted by bridge design experts. The development of a KBS for the conceptual design of concrete road bridges is then described including the knowledge involved, its organization and representation schemes. Working of the KBS is explained through an application example. The main thrust of this-paper is on the critical evaluation of various generated feasible solutions.

ISSN:0263-0257    

DOI:10.1080/02630259608970183

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Earthmoving operations are a major part of many civil engineering works and as such they present an ideal opportunity for improved estimation forecasts and efficiency. This paper presents a computer simulation model which is based on the assumption that an earthmoving cycle can be broken down into its component parts which can be represented by Erlang probability distributions. Such a distribution can be generated on a computer and incorporated into a discrete-event simulation program. The development of the model and of a program to carry out simulation runs is described. The importance of model validity is discussed; results from a simulation cannot be relied upon if the model does not actually agree with the real system. The results of a validation exercise are shown which compares system output data (obtained from actual contracts in the UK) and model output data. Simulation output data is also shown in a graphical form which is intended to ease the use of the model on a site basis.

ISSN:0263-0257    

DOI:10.1080/02630259608970184

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Accurate prediction of the impact of environmental factors on pavement serviceability is important for a pavement design. In this regard, AASHTO Pavement Design Guidelines (1986) provide a rational method of incorporating the effects of roadbed swelling and frost action. According to the AASHTO (1986) procedure, the present serviceability index (PSI) loss of a pavement segment due to environmental factors is estimated by considering factors such as the moisture supply as well as the fabric, swelling potential and frost susceptibility of the roadbed soil. The swelling potential in turn is governed by the plasticity index of the soil and compaction conditions. The current AASHTO procedure requires most of the above attributes to be qualitatively adjudged. Hence, the designer is called upon to use linguistic assessments as “low rainfall”, “poor drainage”, “tight soil fabric”, “normal field moisture and density conditions” and etc. to evaluate them. Consequent to the use of such vague descriptions, the repeatability of the PSI loss estimation procedure is affected.

ISSN:0263-0257    

DOI:10.1080/02630259608970185

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

This paper discusses problems of identifying and estimating the reliability of complex real production systems in the constructing industry. The influence of the system structure on its reliability has been considered. Types of elements and their connections in the system from the point of view of system reliability have been identified.

ISSN:0263-0257    

DOI:10.1080/02630259608970186

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

The Water Rights Analysis Package (WRAP) is a generalized river basin simulation model for evaluating water availability within the framework of a prior appropriation water rights system, such as the permit system recently implemented in Texas. WRAP is used to evaluate water supply reliabilities for permitted water users and unappropriated streamflows available for additional permit applicants. The historic hydrologic period-of-record is simulated using a monthly computational time step. For each monthly interval, a network flow programming algorithm allocates streamflow and reservoir storage resources in accordance with water rights. The model is generalized for application to river/reservoir systems of essentially any configuration. WRAP and its application to the Brazos River Basin illustrate the use of network flow programming in modeling the allocation of a limited water resource to numerous users within a complex institutional setting.

ISSN:0263-0257    

DOI:10.1080/02630259608970187

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

ISSN:0263-0257    

DOI:10.1080/02630259608970188

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor