A Systematic Study of Design Conflict: Modeling, Representation, Resolution, and Application

ABSTRACT A Systematic Study of Design Conflict: Modeling, Representation, Resolution, and Application Baiquan Yan, Ph.D. Concordia University, 2013 Conflicts drive the development of technical systems and the evolution of design process. Conflict management, which mainly includes conflict identification and resolution, is a crucial part of design activity. This research conducts a systematic study and proposes a formal structure of design conflicts. The first step of conflict management is to build up a formal model for technical system. Currently, there exist some inconsistences among different design theories because of the lack of a cohesive set of fundamental concepts about technical systems. This lack also causes misunderstanding among researchers and therefore hinders the development of design theories. This thesis presents a formal approach to representing technical systems. Both theoretical derivation and extensive example have shown that this formal representation meets the five requirements: completeness, clarity, independence, flexibility, and adaptability. A set five concepts— purpose, function, structure, behaviour and state— is identified and formally defined as the base set for technical systems. The second step is to model conflicts based on the formalization of technical system. Current studies are based on heuristics and lack a systematic approach, and therefore fail to detect conflicts that are not predefined. This research puts forward a formal structure of design conflicts based on systematic analysis. This formal structure shows that any conflict is composed of at least three objects: two competing objects and one resource object that the former two contend for. This formal structure can be applied to different design fields and helps designers identify all conflicts existed in different design stages. Based on the formal structure of conflicts and analysis of relation among the three objects in a conflict, this research also proposes three formal methods for detecting conflicts and presents a set of general resolution principles, which include modifying resource object, separating conflict relations in time or in space, changing the two competing objects, using optimization methods, and replacing the whole conflict. An example demonstrates the application of the formal structures, followed with conclusion and suggestions for future research

Experimental approaches for understanding conceptual design activities

Designers play an important and critical role in developing innovative product design, which is the key for a company to survive in the highly competitive market with ever-increasing demands from customers. However, how designers think, reason, judge, and make decisions has not yet been studied well. This thesis aims to develop experimental approaches to qualitatively and quantitatively understand designers' cognitive activities in order to explore product innovation in the early design stages. To study designers' cognitive activities, a new protocol analysis method is developed. In the protocol analysis experiment, designers' activities were recorded when solving a design problem. Designers were interviewed to recall their design process immediately after finishing the design. Then, the recorded verbal data were analyzed by transcribing, segmentation and encoding for further analysis. In general, protocol analysis is used to transform the unstructured data collected from designers into structured data. Existing protocol analysis methods used to study designers' cognitive activities heavily depend on specific design problems, specific domains and the persons who analyze the protocol data. The new protocol analysis method presented in this thesis is based on the concept of the state of design and recursive object model. It can be easily applied to any design problem and any domain. Using this method, the changes of designers' cognitive activities during the design process can be quantified. Some guidelines and recommendations for assisting designers to deliver an innovative design are summarized at the end of the present thesis based on the experimental results. The protocol analysis results have also been used to evaluate Environment-Based Design (EBD) as a descriptive design model; hence, EBD can be used as the theoretical foundation to illustrate, describe, and explain how designers conduct a design task. Another part of my thesis is to simulate the design process by developing a virtual experiment. In the virtual experiment, the selected design problem: finite element mesh design, can be automatically solved using a program developed in the computer environment of Visual C++. Net 2003. Then, different settings of the parameters, different strategies, different formulations of design requirements, and different sequences for solving the design problem are simulated to compare the differences of meshes. Three routes leading designers to innovative designs are proposed and examined through this virtual experiment. Based on the three routes, an ANN-based element extraction method for finite element mesh design is developed to illustrate the feasibility of the three routes for changing design solutions. Therefore, the two experimental approaches proposed in this thesis can be used for understanding design activities in a more systematic manne

An ANN-based element extraction method for automatic mesh generation, Expert Systems with Applications

Abstract This paper proposes an artificial neural network based element extraction method for automatic finite element mesh generation. A finite element mesh is a discretized representation of a geometric domain. A domain is discretized into elements, which may be triangles, quadrilaterals, tetrahedron, or hexahedron. The element extraction method repeatedly generates element (s) within the domain using some predefined 'if-then' rules until the whole domain is filled with required elements. This method has an advantage of creating meshes for domains with complex boundaries. However, the 'if-then' rules for element extraction are usually difficult to acquire, because these rules not only generate elements but also change the problem they are designed to solve. In this paper, a Back-Propagation (BP) neural network is used to represent the 'if-then' element extraction rules and to train the relationship behind these rules. The input for this network includes the coordinates of some boundary points while the output defines the parameters for extracting an element. In order to generate good quality element while keeping the updated problem still solvable, the design and definition of the neural network is more complex than those in the traditional classification problems. This paper discusses issues related to the design of the neural network for element extraction. Numerical experiments on quadrilateral mesh generation have shown that this method is effective.