Showing papers on "Conceptual design published in 1998"

An object oriented approach to Web-based applications design

Abstract: In this paper we discuss the use of an object-oriented approach for web-based applications design, based on a method named Object-Oriented Hypermedia Design Method (OOHDM). We first motivate our work discussing the problems encountered while designing large scale, dynamic web-based applications, which combine complex navigation patterns with sophisticated computational behavior. We argue that a method providing systematic guidance to design is needed. Next, we introduce OOHDM, describing its main activities, namely: conceptual design, navigational design, abstract interface design and implementation, and discuss how OOHDM designs can be implemented in the WWW. Finally, related work and future research in this area are further discussed. © 1998 John Wiley & Sons, Inc.

Conceptual design of data warehouses from E/R schemes

Abstract: Data warehousing systems enable enterprise managers to acquire and integrate information from heterogeneous sources and to query very large databases efficiently. Building a data warehouse requires adopting design and implementation techniques completely different from those underlying information systems. We present a graphical conceptual model for data warehouses, called Dimensional Fact model, and propose a semi-automated methodology to build it from the pre-existing entity/relationship schemes describing a database. Our conceptual model consists of tree-structured fact schemes whose basic elements are facts, attributes, dimensions and hierarchies; other features which may be represented on fact schemes are the additivity of fact attributes along dimensions, the optionality of dimension attributes and the existence of non-dimension attributes. Compatible fact schemes may be overlapped in order to relate and compare data. Fact schemes may be integrated with information of the conjectured workload, expressed in terms of query patterns, to be used as the input of a design phase whose output are the logical and physical schemes of the data warehouse.

A methodological framework for data warehouse design

Abstract: Though designing a data warehouse requires techniques completely different from those adopted for operational systems, no significant effort has been made so far to develop a complete and consistent design methodology for data warehouses. In this paper we outline a general methodological framework for data warehouse design, based on our Dimensional Fact Model (DFM). After analyzing the existing information system and collecting the user requirements, conceptual design is carried out semi-automatically starting from the operational database scheme. A workload is then characterized in terms of data volumes and expected queries, to be used as the input of the logical and physical design phases whose output is the final scheme for the data warehouse.

Current research in the conceptual design of mechanical products

Abstract: Decisions made at the conceptual design stage have significant influence on factors such as costs, performance, reliability, safety and environmental impact of a product. However, knowledge of all the design requirements and constraints during this early phase of a product's life cycle is usually imprecise, approximate or unknown. Faced with such complexity, individual designers have restricted themselves to narrow, well-defined sub-tasks and as a result, progress in this area has been patchy and spasmodic. The purpose of this survey is to document the current state of research and development in this crucial design activity and in doing so, to identify avenues of fruitful exploration. In this paper, we provide a comparison of the advantages/disadvantages and limitations between the various techniques/tools and, where applicable, suggest possible future research directions.

An object-oriented representation for product and design processes

Abstract: We report on the development of a knowledge representation model, which is based on the SHARED object model reported in Shared Workspaces for Computer-Aided Collaborative Engineering (Wong, A. and Sriram, D., Technical Report, IESL 93-06, Intelligent Engineering Systems Laboratory, Department of Civil Engineering, MIT, March, 1993) and Research in Engineering Design (Wong, A. and Sriram, D., SHARED: An Information Model for Cooperative Product Development, 1993, Fall, 21-39). Our current model is implemented as a layered scheme, that incorporates both an evolving artifact and its associated design process. To represent artifacts as they evolve, we define objects recursively without a pre-defined granularity on this recursive decomposition. This eliminates the need for translations between levels of abstraction in the design process. The SHARED model extends traditional OOP in three ways: 1. by allowing explicit relationship classes with inheritance hierarchies; 2. by permitting constraints to be associated with objects and relationships; and 3. by comparing `similar' objects at three different levels (form, function and behavior). Five primitive objects define the design process: goal, plan, specification, decision and context. Goal objects achieve function, introduce constraints, introduce new artifacts or modify existing ones, and create subgoals. Plan objects order goals and link a product hierarchy to a process hierarchy. Specification objects define user inputs as constraints. Decision objects relate goals to user decisions and context objects describe the design context. Operators that are applied to design objects collectively form a representation of the design process for a given context. The representation is robust enough to effectively model four design paradigms [described in Journal of CAD (Gorti, S. and Sriram, R. D., Symbol to Form Mapping: a Framework for Conceptual Design, 1996, 28 (11), 853–870)]: top-down decomposition, step-wise refinement, bottom-up composition and constraint propagation. To demonstrate this, we represent the designs of two TV remote controllers in the SHARED architecture. The example reveals that certain aspects of artifact knowledge are essentially context-independent and that this representation can be a foundation for robust knowledge-based systems in design.

Understanding conceptual electronic design using protocol analysis

Abstract: Many theories about the process, of design have been derived from prescriptive or descriptive analysis. There have been few attempts to empirically test these theories. Protocol analysis facilitates detailed inspection of the design process allowing design task analysis across the temporal dimension. Some hypotheses about the design process, derived from the literature, are objectively tested using results obtained from protocol analyses of various electronics designers engaged in conceptual design. Support for the hypotheses is found.

Analyzing Software Specifications for Mode Confusion Potential

Abstract: Increased automation in complex systems has led to changes in the human controller's role and to new types of technology-induced human error. Attempts to mitigate these errors have primarily involved giving more authority to the automation, enhancing operator training, or changing the interface. While these responses may be reasonable under many circumstances, an alternative is to redesign the automation in ways that do not reduce necessary or desirable functionality or to change functionality where the tradeoffs are judged to be acceptable. This paper describes an approach to detecting error-prone automation features early in the development process while significant changes can still be made to the conceptual design of the system. The information about such error-prone features can also be useful in the design of the operator interface, operational procedures, or operator training.

Developing Hypermedia Applications using OOHDM

Abstract: In this paper we discuss the use of an object-oriented approach for hypermedia applications design, including web-based, based on the Object Oriented Hypermedia Design Method (OOHDM). We first motivate our work discussing the problems encountered while designing large scale, dynamic web-based applications, which combine complex navigation patterns with sophisticated computational behavior. We argue that a method providing systematic guidance to design is needed. Next, we introduce OOHDM, describing its main activities, namely: conceptual design, navigational design, abstract interface design and implementation, and discuss how OOHDM designs can be implemented in the WWW. Finally, related work and future research in this area are further discussed. 1. A Brief Overview of OOHDM The Object-Oriented Hypermedia Design Method is a model-based approach for building large hypermedia applications. It has been used to design different kinds of applications such as: web sites and information systems, interactive kiosks, multimedia presentations, etc. OOHDM comprises four different activities namely, Conceptual Design, Navigational Design, Abstract Interface Design and Implementation. They are performed in a mix of incremental, iterative and prototype-based development styles. During each activity a set of object-oriented models describing particular design concerns are built or enriched from previous iterations. As we explain below, treating conceptual, navigational and interface design as separate activities allows us to concentrate on different concerns one at a time. As a consequence we get more modular and reusable designs, and we obtain a framework to reason on the design process, encapsulating design experience specific to that activity. Besides, the interface design primitives can be easily mapped to non object-oriented implementation languages or environments (such as HTML or Toolbook) and thus OOHDM can be used regardless of whether the target system is a pure object-oriented environment one or a hybrid one (as those we usually find in the Internet). In Figure 1 we show a sketch of the activities in OOHDM and in Figure 2 we briefly describe OOHDM activities, primitives, concerns and abstraction mechanisms (an extension of the one shown in [Schwabe 95]).

Design components: towards software composition at the design level

Abstract: Component-based software development has proven effective for systems implementation in well-understood application domains, but is still insufficient for the creation of reusable and changeable software architectures. Design patterns address these shortcomings by capturing the expertise that is necessary for reusable design solutions. However, there is so far no methodical approach to providing these conceptual design building blocks in a tangible and composable form. To address this limitation, we introduce the notion of design components, reified design patterns fit for software composition. In this paper, we define design components and explain their constituents and services. Furthermore, we detail the activities of design composition and illustrate them as a process within a four-dimensional design space. Moreover, we describe a prototype of a design composition environment. A case study helps illustrating our approach.

A methodology for modelling manufacturing costs at conceptual design

Abstract: This paper describes a method for modelling costs throughout the design phase of a product's life-cycle, from conceptual to detail design. The timely provision of cost data facilitates the quantitative evaluation of designs through a cost function. This approach to design evaluation has the advantages of allowing management to make more accurate bid estimates, encouraging designers to design to cost and reducing the amount of design rework, hence reducing the product's time to market and controlling product cost. The cost modelling strategy adopted incorporates the use of knowledge-based and case-based approaches. Cost estimation is automated by linking design knowledge, required for predicting design features from incomplete design descriptions, to production knowledge. The link between the two knowledge paradigms is achieved through the blackboard framework of problem solving, which incorporates both case-based and rule-based reasoning. The method described is aimed at innovative design activity.

Representation of Design Object Based on the Functional Evolution Process Model

Abstract: One of the crucial issues for developing computer aided conceptual design system is representation of functions which represent designers’ intention. Representing functions is also crucial not only for representing design objects but also for describing conceptual design processes, in which designers operate mainly functional concepts. Namely, function is a key concept to integrate object modeling and process modeling in design. In this paper, first we extend the FBS (Function-Behavior-State) diagram, which we have already proposed, by introducing three additional concepts for representing a function; namely, function body that represents designers’ intention directly, function modifier that qualifies a function body, and objective entity on which the function body occurs. This extended FBS diagram, called FBS/m (modifier) diagram, enables us to represent designers’ intention more precisely than the original FBS diagram. Then, we propose an FEP (Functional Evolution Process) model to represent design processes. In the FEP model, the FBS model of a design object is evolved through three steps, i.e., functional actualization, functional evaluation and functional operation. Functional actualization depicts a process to obtain physical descriptions from functional description. Functional evaluation is a process to measure realizability of functions of the design object. Functional operation is a process to operate functions to improve the design. Based on the FEP model, we analyze an actual design process, and show that the FEP model is suitable for representing designers’ intention along with design processes.

Integrating culture into interface design

Abstract: In this paper, I describe how culture impacts usability and design, present a package of variables for identifying cultural differences, and give localization suggestions. I also present ideas for research leading to specific guidelines for integrating culture into design

Profit-Optimizing Product Line Design, Selection and Pricing with Manufacturing Cost Consideration

Abstract: Much of the literature on product line design or product line selection focuses on revenue or market share maximization, but in many cases, the true objective is to maximize profit In this paper, we survey the literature on models that address decisions regarding the conceptual design of products to be offered, or the selection of products among a large set of potential products, and, in some cases, the prices of the offered products We focus on the combined effects of multiple product offerings on both revenue and manufacturing costs, and emphasize models that would accommodate variable manufacturing costs, the cost of manufacturing facilities, and/or engineering design costs of some form The paper concludes with promising directions for future research

Optimal Configuration Design: An Integrated Approach Using Grammars

Abstract: A computational approach to design that integrates conceptual design, configuration design, and component selection tasks overcomes some of the barriers to successful design automation. FFREADA is an implementation of a general design generation and optimization algorithm featuring hierarchical ordering of grammar-based design generation processes at different levels of abstraction. FFREADA is used to generate near-optimal hand-held drill power trains in a space exceeding 200 million designs that are not limited to any particular functional architecture or component configuration. Drill power train designs with values within I percent of the optimal solution are found in minutes by sampling 302, 000 design states on average. Optimal configurations are found for drill power trains with three different torque requirements.

Integrated intelligent design and assembly planning: A survey

Abstract: This paper reviews the relevant literature of the development of methodologies and systems for integrated intelligent design of assembled products and processes. Based on a combination of the concurrent engineering approach and artificial intelligence techniques, an assembly oriented intelligent scheme for the integration of design and planning is proposed, in which the following components or activities are considered and carried out concurrently and intelligently: assembly modelling and design (conceptual design; preliminary design; detailed design), assembly process planning, assembly system layout and design, assembly simulation, econo-technical (e.g. assembl-ability, assembly time and cost) and ergonomic analysis and evaluation. The literature is reviewed and discussed in relation to the methodologies and systems of implementing the above components or activities and an integrated environment to support them. In addition, some research of our group on this topic is introduced.

Systems engineering and analysis. Third edition

Abstract: The topics presented in this book have been organized into 6 parts and 19 chapters. Part 1 presents an introduction to systems and systems engineering in the context of system science and good engineering practice. Part 2 addresses the system design process as a series of evolutionary steps, progressing from the identification of a need through conceptual design, preliminary design, detail design and development, and test and evaluation. Part 3 derives some of the most useful mathematical models and tools for systems analysis. Emphasis is placed upon the application of modeling and analysis techniques as an integral part of the systems engineering process. Part 4 addresses design for operational feasibility by discussing those characteristics of design found to be most significant for successful system operation and customer satisfaction. Separate chapters are devoted to reliability, maintainability, usability (human factors), supportability (serviceability), producibility, disposability, and affordability (life-cycle cost). Part 5 presents an overview of systems engineering management, with planning and organization discussed in one chapter and program management and control in another. Part 6 contains a set of comprehensive appendices providing supporting topics, checklists, tables, references, and related resource materials.

An architecture for exploring large design spaces

Abstract: We describe an architecture for exploring very large design spaces, for example, spaces that arise when design candidates are generated by combining components systematically from component libraries. A very large number of candidates are methodically considered and evaluated. This architecture is especially appropriate during the stage of conceptual design when high-level design decisions are under consideration, multiple evaluation criteria apply, and a designer seeks assurance that good design possibilities have not been overlooked. We present a filtering technique based on a dominance criterion that can be used to select, from millions of design candidates, a relatively small number of promising candidates for further analysis. The dominance criterion is lossless in that it insures that each candidate not selected is inferior to at least one of the selected candidates. We also describe an interactive interface in which the selected designs are presented to the designer for analysis of tradeoffs and further exploration. In our current implementation, the computational load is distributed among a large number of workstations in a client-server computing environment. We describe the results of experiments using the architecture to explore designs for hybrid electric vehicles. In a recent experiment more than two million distinct designs were evaluated.

Conceptual predesign bridging the gap between requirements and conceptual design

Abstract: To overcome the impedance mismatch between requirement analysis and conceptual design, we introduce an intermediate step between the two phases, called conceptual pre-design. A (semantic) model for that phase should allow for an easy collection of requirements as well as for an unproblematic transformation of the collected requirements into entries of a conceptual scheme. We present a model that has been developed along these postulates. Following the classical DATA-ID approach, this model uses a "glossary metaphor" for scheme representation. It's basic semantic notions are 'thing type' and 'connection type'.

Conceptual design of free flight with airborne separation assurance

Abstract: The study described in this paper originally only aimed at studying the human factors problems of airborne separation hi a Free Flight environment. However to define the Free Flight environment with sufficient detail, a concept was designed at NLR. This conceptual design includes rules-of-the-sky, a conflict resolution algorithm, conflict detection, cockpit display recommendations, system description as well as operational implications. The feasibility of the design has been evaluated in three sub-studies: (i) off-line traffic simulations with very high traffic densities and a total of up to 300 aircraft, (ii) a safety analysis comparing the resolution method with current day ATC and (iii) a man-in-the-loop simulator experiment hi traffic densities up to three times the average WestEuropean traffic density with eight air line crews. None of these studies could refute the feasibility of the Free Flight conceptual design.

Conceptual design using a synergistically compatible morphological matrix

Abstract: The morphological matrix is a key methodology that can improve the effectiveness of the concept generation phase of the design process. However, as discussed in the paper, there are difficulties identifying independent design functions and determining the synergistic compatibility of combining solution alternatives. In order to address these difficulties, the authors extend the morphological matrix methodology by including the theory of coupling. A case study is presented to illustrate the overall methodology and its impact.

Ontology-Based Multimedia Data Mining for Design Information Retrieval

Abstract: Design information systems rich multimedia content with symbolic retrieval Design information systems serve different purposes during different phases of the design process. During the early conceptual design stage the information they define the required function and the constraints, and sketches indicate the alternatives considered. Once a partial design is developed, they provide information for its further elaboration. During later stages designers need information about the physical components for the detailing the design solution. If the final design is used and constructed, there is also a need to collect and file related information for later recall. It is not surprising that design information systems probably span the whole variety of today's multimedia information systems, as shown in Figure 1.

Displacement feature modelling for conceptual design

Abstract: Although the support of surface features, where a surface feature represents a local geometric detail imposed on a surface, is welldefined on prismatic objects, this is not the case for sculptured surface models. Current methods often lead to data-explosion, high polynomial results, or procedural solutions. In this paper a method is described that allows explicit modelling of protrusions and depressions in free-form B-spline surfaces. As this functionality is intended to be used by industrial designers during conceptual design, distinct requirements are formulated to allow its use in this early stage of design. A method is described that calculates a blending geometry approximating G 1 cross-boundary smoothness effectively. Using these requirements and approximations, protrusions and depressions can be modelled with real-time response, and with unprecedented flexibility.

A-Design: Theory and Implementation of an Adaptive, Agent-Based Method of Conceptual Design

Abstract: A new theory of engineering design known as A-Design is introduced that models the workings of realistic engineering design in a complex adaptive system of interacting software agents. The methodology is general enough to be used on a variety of search problems, however the motivation behind the research is to create design configurations. The system constructs meaningful designs from a catalog of electromechanical components based on a variety of user-defined objectives while accom—modating changes that might occur in the focus of the problem.

Tool for the Management of Concurrent Conceptual Engineering Design

Abstract: The following article presents in summary, a prototype computational tool supporting localized design agents in the generation and management of conceptual engineering design variants within a distributed concurrent engineering design environment.

Getting the Full Benefits of CFD in Conceptual Design

Abstract: The applied aerodynamics community is struggling to develop a means of incorporating computational fluid dynamics (CFD) into the early stages of aircraft systems design, where it can have the greatest impact on vehicle design. This paper describes developments in computational design methodology arising from research into multidisciplinary design optimization (MDO) done recently by the authors that addresses this problem. The premise is that advanced CFD should be used to precompute a database of solutions which is then interpolated during the design process. Design of experiments theory is used to select the "conditions" or "design points" used to populate the database, and statistical methods are then used to develop a mathematical model of the CFD solutions which is used to "interpolate" the database. The specific models we use, called "response surface models" are quadratic least squares fits to functions of the CFD results. Populating the database is made possible through the use of coarse grained parallel computing. We demonstrate the method using a recent example from our MDO work.

The Aerospace Corporation’s Concept Design Center

Abstract: The Concept Design Center (CDC) developed by The Aerospace Corporation has enhanced support to its customers by providing a process for bringing together the conceptual design capabilities and experts throughout The Aerospace Corporation. The members meet as a group on an as-needed basis in a computer laboratory to create and evaluate conceptual designs in a synergistic and concurrent manner. The CDC consists of a number of teams, each of which focuses on a different segment of the mission. This paper will focus on the general characteristics of the CDC and on the Space Segment Team (SST) whose primary function is the conceptual design of the spacecraft.