Al Johnson

The retrieval of structured design rationale for the re-use of design knowledge with an integrated representation

Design knowledge can be acquired from various sources and generally requires an integrated representation for its effective and efficient re-use. Though knowledge about products and processes can illustrate the solutions created (know-what) and the courses of actions (know-how) involved in their creation, the reasoning process (know-why) underlying the solutions and actions is still needed for an integrated representation of design knowledge. Design rationale is an effective way of capturing that missing part, since it records the issues addressed, the options considered, and the arguments used when specific design solutions are created and evaluated. Apart from the need for an integrated representation, effective retrieval methods are also of great importance for the re-use of design knowledge, as the knowledge involved in designing complex products can be huge. Developing methods for the retrieval of design rationale is very useful as part of the effective management of design knowledge, for the following reasons. Firstly, design engineers tend to want to consider issues and solutions before looking at solid models or process specifications in detail. Secondly, design rationale is mainly described using text, which often embodies much relevant design knowledge. Last but not least, design rationale is generally captured by identifying elements and their dependencies, i.e. in a structured way which opens the opportunity for going beyond simple keyword-based searching. In this paper, the management of design rationale for the re-use of design knowledge is presented. The retrieval of design rationale records in particular is discussed in detail. As evidenced in the development and evaluation, the methods proposed are useful for the re-use of design knowledge and can be generalised to be used for the retrieval of other kinds of structured design knowledge.

CADET: A software support tool for constraint processes in embodiment design

For the last two decades there has been an attempt to put more “design” in computer-aided design (CAD) through improving CAD for conceptual design, embodiment design, design for manufacturing, and design for environment. This article presents computational methods for supporting constraint specification and satisfaction in mechanical embodiment design. The methods were tested and their feasibility verified through the implementation of the prototype software support tool, CADET (computer-aided-design embodiment tool). CADET is capable of rapidly specifying and satisfying large sets of algebraic design constraints. This article describes the product model developed to maintain design information and describes the use of generic component libraries to automate the specification of design constraints. In addition, adaptive search algorithms to find feasible designs to satisfy the imposed constraints are presented.

Towards a collaborative modeling and simulation platform on the Internet

The design and development of complex engineering systems, e.g. mechatronics, is increasingly characterized as an interdisciplinary process, which entails the co-operative work of distributed teams. However, traditional simulation tools generally emphasize discipline-oriented purposes and centralized running, and cannot adequately support the collaborative simulation in a distributed environment. Although some tools have been developed to enable remote access to simulations, most of them focus on the sharing of information and the provision of simulations via a single and centralized program. The long-term aim of this research is to develop a collaborative modeling and simulation platform, which will provide an integrated environment for multi-disciplinary teams to create, share, and integrate simulation services on the Internet. A step towards such a platform is described which includes the infrastructures for distributed communication, the mechanism for run-time interaction, and the representation of a simulation system at the abstract level. In this paper, we will (1) formulate a collaborative simulation problem; (2) identify the factors influencing the performance of a simulation; (3) propose a method for run-time interaction to achieve optimal simulation accuracy; and (4) illustrate how the components serving different purposes are integrated. A case study is described, based on a prototype implementation of the proposed solution, to explore supporting collaborative simulation in an Internet-distributed environment.

Designing by functions

Abstract Present-day CAD packages play only a small part in the central arena of mechanical engineering design, which involves the synthesis and embodiment of physical components to perform a pre-determined function without unwanted side-effects. The computer cannot properly help the designer in this task until it is able to capture and process the functional requirements of the design. Functional modelling provides a method for achieving this, and raises some challenging geometrical and programming problems.

A Method and Software Tool for Automated Gearbox Synthesis

In today’s economy, engineering companies strive to reduce product development time and costs. One approach to assisting this goal is to introduce computer-aided methods and tools earlier in the development process. This requires providing robust design automation methods and tools that can support design synthesis and the generation of alternative design configurations, in addition to automated geometric design. A new method for automated gearbox design, tailored for integration within an existing commercial gearbox analysis tool, is described in this paper. The method combines a rule-based generative approach, based on a previous parallel grammar approach for mechanical gear systems, with domain specific heuristics and stochastic search using simulated annealing. Given design specifications that include a bounding box, the number of required speeds and their target ratios, a range of valid gearbox configurations is generated from a minimal initial configuration. Initial test results show that this new method is able to generate a variety of designs which meet the design specifications. The paper concludes with a discussion of the method’s current limitations and a description of the work currently underway to improve and extend its capabilities.Copyright

On estimating the feasible solution space of design

The feasible solution space for a mechanical engineering design is determined by the variables and constraints involved in the design. Although constraint satisfaction programs can be used to find individual solutions in this space, their search strategies become very inefficient if the search space is much larger than the solution space. The user then cannot be sure whether a prolonged unsuccessful search is due to this inherent inefficiency, or because no solution space actually exists. In addition, such programs provide no information about the amount by which a satisfactory design solution can be adjusted without violating any constraints. This paper presents the implementation of a computer program which utilises a domain propagation algorithm to estimate the feasible design space. The theoretical descriptions of domain propagation and the algorithm are also discussed. Case studies show that this program enhances the efficiency and robustness of the constraint-based design process.

A collaborative system for capturing and reusing in-context design knowledge with an integrated representation model

Current research on design knowledge capture and reuse has predominantly focused on either the codification view of knowledge or the personalisation view of knowledge, resulting in a failure to address designers’ knowledge needs caused by a lack of context of information and insufficient computational support. Precisely motivated by this gap, this work aims to address the integration of these two views into a complete, contextual and trustworthy knowledge management scheme enabled by the emerging collaborative technologies. Specifically, a knowledge model is developed to represent an integrated knowledge space, which can combine geometric model, knowledge-based analysis codes and problem-solving strategies and processes. On this basis, a smart collaborative system is also designed and developed to streamline the design process as well as to facilitate knowledge capture, retrieval and reuse as users with different roles are working on various tasks within this process. An engineering case study is undertaken to demonstrate the idea of collaborative knowledge creation and sharing and evaluate the effectiveness of the knowledge representation model and the collaborative technologies employed. As evidenced in the development and evaluation, the methods proposed are effective for capturing an integrated knowledge space and the collaborative knowledge management system not only facilitates problem-solving using knowledge-based analysis but also supplies in-context tacit knowledge captured from the communications between users throughout the design process.

Requirements and use of in-service information in an engineering redesign task: Case studies from the aerospace industry

A huge number of informal messages are posted every day in social network sites, blogs, and discussion forums. Emotions seem to be frequently important in these texts for expressing friendship, showing social support or as part of online arguments. Algorithms to identify sentiment and sentiment strength are needed to help understand the role of emotion in this informal communication and also to identify inappropriate or anomalous affective utterances, potentially associated with threatening behavior to the self or others. Nevertheless, existing sentiment detection algorithms tend to be commercially oriented, designed to identify opinions about products rather than user behaviors. This article partly fills this gap with a new algorithm, SentiStrength, to extract sentiment strength from informal English text, using new methods to exploit the de facto grammars and spelling styles of cyberspace. Applied to MySpace comments and with a lookup table of term sentiment strengths optimized by machine learning, SentiStrength is able to predict positive emotion with 60.6p accuracy and negative emotion with 72.8p accuracy, both based upon strength scales of 1–5. The former, but not the latter, is better than baseline and a wide range of general machine learning approaches.

Towards real CAD

Abstract Present-day computer-aided design (CAD) packages play only a small part in the area of mechanical engineering design, which involves the synthesis and embodiment of physical components to perform a pre-determined function without unwanted side effects. The computer cannot properly help the designer in this task until it is able to capture and process the function requirements of the design. This paper describes the computer system being developed for this purpose at the Engineering Design Centre at Cambridge University Engineering Department. The paper also explores some of the geometrical and programming implications raised.

The Assembly of Computational Models for the Collaborative Development of Virtual Prototypes

In the context of collaborative product development, new requirements need to be accommodated for Virtual Prototyping Simulation (VPS), such as distributed processing and the integration of models created using different tools or languages. Existing solutions focus mainly on the implementation of distributed processing, but this paper explores the issues of combining different models (some of which may be proprietary) developed in different software environments. In this paper, we discuss several approaches for developing VPS, and suggest how it can best be integrated into the design process. An approach is developed to improve collaborative work in a VPS development by combining disparate computational models. Specifically, a system framework is proposed to separate the system-level modeling from the computational infrastructure. The implementation of a simple prototype demonstrates that such a paradigm is viable and thus provides a new means for distributed VPS development.Copyright