David W. Fowler

The Designers’ Workbench: Using Ontologies and Constraints for Configuration

Typically, complex engineering artifacts are designed by teams who may not all be located in the same building or even city. Additionally, besides having to design a part of an artifact to be consistent with the specification, it must also be consistent with the company’s design standards.

Issues in Moving to a Semantic Web for a Large Corporation

In many large engineering design organizations the information systems have developed over time into a set of heterogeneous resources. This makes it difficult for engineers to follow a trail through the resources. This situation becomes particular difficult when the Engineer is new to a company; unfamiliar with the systems and unaware of the history of the designs. This paper presents a demonstrator system developed with a major aerospace company to aid engineers, through the use of knowledge technologies, to locate the documentation they require. The paper presents the systems and lessons learnt to enable the organisation to move towards a more semantically enriched document repository.

Branching Constraint Satisfaction Problems and Markov Decision Problems Compared

Branching Constraint Satisfaction Problems (BCSPs) model a class of uncertain dynamic resource allocation problems. We describe the features of BCSPs, and show that the associated decision problem is NP-complete. Markov Decision Problems could be used in place of BCSPs, but we show analytically and empirically that, for the class of problems in question, the BCSP algorithms are more efficient than the related MDP algorithms.

Branching Constraint Satisfaction Problems for Solutions Robust under Likely Changes

Many applications of CSPs require partial solutions to be found before all the information about the problem is available. We examine the case where the future is partially known, and where it is important to make decisions in the present that will be robust in the light of future events. We introduce the branching CSP to model these situations, incorporating some elements of decision theory, and describe an algorithm for its solution that combines forward checking with branch and bound search. We also examine a simple thresholding method which can be used in conjunction with the forward checking algorithm, and we show the trade-off between time and solution quality

Requirements for Semantic Web Aapplications in Engineering

In this paper we describe some applications of Semantic Web technologies for the engineering design community. Specifically, we use Semantic Wikis to form a central knowledge base, which other applications then refer to. The developed applications include an advisor for performing Computational Fluid Dynamics simulations, a Semantic search engine, and an assistant for airfoil design. In the conclusions we discuss lessons learned and subsequently requirements for future systems.

ConEditor: Tool to Input and Maintain Constraints

We present a tool which helps domain experts capture and maintain constraints. The tool displays parts of an ontology (as classes, sub-classes and properties) in the form of a tree. A number of keywords and operators from a constraint language are also listed. The tool helps a user to create a constraint expression. Additionally, the tool has a facility which allows the user to input tabular data. The expressed constraints can be converted into a standard format, making them portable. It is planned to integrate this tool, ConEditor, with Designers’ Workbench, a system that supports human designers.

An information system to support the engineering designer

Engineering companies are currently shifting their focus from selling products to providing services, hence the products’ designers must increasingly consider life-cycle requirements, in addition to conventional design parameters. To identify possible areas of concern, engineers must consider knowledge throughout the life cycle of similar or related products. However, because of the size and distributed nature of a company’s operation, engineers often do not have access to front-line maintenance data. In addition, the large number of documents generated during the design and operation of a product makes it impractical to manually review all documents thoroughly during a task. As a case study, this paper discusses the concept and development of a large hypermedia based Knowledge Desktop that has been developed to support the maintenance and future design of aircraft engines. As part of the development cycle, the performance of the software and its acceptance by the user community has been fully evaluated. The evaluation method considered in this paper focuses on the subjective opinion of the users and measures the ease with which users could retrieve the information required to perform specific tasks.

Enhancing Grid Service Discovery with a Semantic Wiki and the Concept Matching Approach

An important challenge of realizing the vision of Grid computing that heterogeneous resources are shared in dynamic and multi-institutional virtual organization is that users need to locate, find, select and invoke appropriate Grid services on demand. However, at the current stage, both Grid resource description and discovery mechanisms are still at an immature stage. This paper presents a semantic solution for flexible Grid service discovery. The service description knowledge is collected by using a semantic wiki, and the proposed service matching approach compares the semantic content of user requests against service advertisements and provides a ranked list of candidate service. Based on them, a service information middleware has been developed and integrated into the service-oriented Grid environment, facilitating an enhanced Grid access for users.

NAVIGATION OVER A LARGE ONTOLOGY FOR INDUSTRIAL WEB APPLICATIONS

Ontologies for industrial semantic web applications are often very large. This is especially true in scientific and engineering applications where there exists a large pool of technical terminology necessary for operation within the domain. In this paper we look at the problem of presenting this domain ontology to users for navigation within web applications. The conventional tree view can be considered to be cumbersome and awkward to navigate for ontologies that have a very large breadth and/or depth. We present three approaches to this ontology presentation problem—content dependent filtering, autocompletion text box and partial segments using drop-down lists. All the approaches attempt to limit the ontology presented to users at one time. We implemented two of the proposed methods of ontology presentation in our demonstrators, and have received positive and valuable feedback from engineers.

Decision Network Semantics of Branching Constraint Satisfaction Problems

Branching Constraint Satisfaction Problems (BCSPs) have been introduced to model dynamic resource allocation subject to constraints and uncertainty. We give BCSPs a formal probability semantics by showing how they can be mapped to a certain class of Bayesian decision networks. This allows us to describe logical and probabilistic constraints in a uniform fashion. We also discuss extensions to BCSPs and decision networks suggested by the relationship between the two formalisms.