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This thesis investigates the novel idea of using a computer to create and optimise conceptual designs of a range of differently-shaped three-dimensional solid objects from scratch. An extensive literature review evaluates all related areas of research and reveals that no such system exists. The development of a generic evolutionary design system, using a genetic algorithm (GA) as its core, is then presented. The thesis describes a number of significant advances necessitated by the development of this system. Firstly, a new low-parameter spatial-partitioning representation of solid objects is introduced, which allows a wide range of solid objects to be appropriately defined and easily manipulated by a GA. Secondly, multiobjective optimisation is investigated to allow users to define design problems without fine-tuning large numbers of weights. As a result of this, the new concepts of acceptability, range-independence and importance are introduced and a new multiobjective ranking method is identified as being most appropriate. Thirdly, variable-length chromosomes in GAs are addressed, to allow the number of primitive shapes that define a design to be variable. This problem is overcome by the use of a new hierarchical crossover operator, which uses the new concept of a semantic hierarchy to reference chromosomes. Additionally, the thesis describes how the performance of the GA is improved by using an explicit mapping stage between genotypes and phenotypes, steady-state reproduction with preferential selection, and a new lifespan limiter. A library of modular evaluation software is also presented, which allows a user to define new design problems quickly and easily by picking combinations of modules to guide the evolution of designs. Finally, the feasibility of the generic evolutionary design of solid objects is demonstrated by presenting the successful evolution of both conventional and unconventional designs for fifteen different solid-object design tasks, e.g. tables, heatsinks, penta-prisms, boat hulls, aerodynamic cars.

Many designers find computer-based tools are not as effective during the early stages of design as manual sketching. However, to abandon the computer in these conceptual stages denies designers the computer‟s capability to translate and supplement imaginative design thinking. Recent design studies address conceptual design. What is the impact of computer-based drawing and sketching on designers‟ cognition and productive reasoning? This research focuses on the relationship between the characteristics of sketching using the drawing environment of the computer and the productivity of the conceptual design phase. I provide a theoretical framework that identifies and clarifies both sketching and productivity. Previous specialized studies are selective and sometimes only descriptive in defining this relationship. A review of these studies reveals a gap in our understanding of those aspects of sketching that relate to visualization, imagination and the generation of design ideas. The thesis addresses three objectives: (i) to build a comprehensive theoretical framework that on one hand defines the characteristics of sketching that might affect the generation of design ideas, and on the other hand defines the productivity of conceptual design and its indicators; (ii) to apply this framework in a practical study; and (iii) to extract implications for the relationship. To address the problem of computer-based sketching, I indentify the continuity within the dynamic field of images usually generated while designers sketch as the most effective characteristic of the computer sketching process. I establish a measure of continuity defined by (i) the degree of ease in projecting design images, (ii) the degree of continuity of displaying images due to changing the status of the design objects and due to navigation around the objects, (iii) the degree of provision of a holistic view (i.e., the total view of the design objects on the computer screen). Then I define productivity within this framework in terms of the cognitive operations of dialogical reinterpretation. When sketching, designers seem to perform key operations such as interpreting, reframing and restructuring. I present the case that a process rich with these cognitive operations is productive. The study makes use of the fields of free hand sketching, literature, cognitive psychology and Gestalt theory. Four indicators emerge from this study: the occurrence of pattern discovery, conceptual reinterpretation, alternation of thinking, and restructuring. I identify key variables that define the degree of continuity of the dynamic field of images which relate to designer‟s performance to verify their relationship with productivity. I study ten design participants who are given a design task that involves sketching with various CAD systems. The study involves 21 hours of recorded video analyzed using a method adapted from Goldschmidt's “linkography” tool for representing design protocols. I identify where patterns of relationships between variables exist, and where they do not apply. Not all the selected variables of continuity of the dynamic field of images, nor all the indicators of productivity in the conceptual design phase, support these patterns of relationships. This indicates that there is a special group of characteristics of sketching that maintain the pace of continuity within the dynamic field of images can improve the productivity in the conceptual phase.

Graphic Design by definition, is conceptual, its birth and production process depends on the conceptualization of problems and solutions. This report will explore what role does conceptual art, and conceptual strategies, play in the applied arts or visual communications. Just as in conceptual art, in graphic design “…the aesthetics of the design is less important than the “product” it signifies; its meaning is more important than its appearance.” Strong examples of conceptual strategies will be described through the work of graphic designers Paul Rand, Allan Fleming, and Robert Brownjohn, who experiment with “defamiliarizing the ordinary” and advertising campaigns that have used a conceptual approach. / text

Performance and manufacturability are two important issues that must be taken into account during MEMS design. Existing MEMS design models or systems follow a process-driven design paradigm, that is, design starts from the specification of process sequence or the customization of foundry-ready process template. There has been essentially no methodology or model that supports generic, high-level design synthesis for MEMS conceptual design. As a result, there lacks a basis for specifying the initial process sequences. To address this problem, this paper proposes a performance-driven, microfabrication-oriented methodology for MEMS conceptual design. A unified behaviour representation method is proposed which incorporates information of both physical interactions and chemical/biological/other reactions. Based on this method, a behavioural process based design synthesis model is proposed, which exploits multidisciplinary phenomena for design solutions, including both the structural components and their configuration for the MEMS device, as well as the necessary substances for the chemical/biological/other reactions. The model supports both forward and backward synthetic search for suitable phenomena. To ensure manufacturability, a strategy of using microfabrication-oriented phenomena as design knowledge is proposed, where the phenomena are developed from existing MEMS devices that have associated MEMS-specific microfabrication processes or foundry-ready process templates. To test the applicability of the proposed methodology, the paper also studies microfluidic device design and uses a micro-pump design for the case study. / Singapore-MIT Alliance (SMA)

In the current Navy environment of undersea weapons development, the engineering aspect of design is decoupled from the development of the tactics with which the weapon is employed. Tactics are developed by intelligence experts, warfighters, and wargamers, while torpedo design is handled by engineers and contractors. This dissertation examines methods by which the conceptual design process of undersea weapon systems, including both torpedo systems and mine counter-measure systems, can be improved. It is shown that by simultaneously designing the torpedo and the tactics with which undersea weapons are used, a more effective overall weapon system can be created. In addition to integrating torpedo tactics with design, the thesis also looks at design methods to account for uncertainty. The uncertainty is attributable to multiple sources, including: lack of detailed analysis tools early in the design process, incomplete knowledge of the operational environments, and uncertainty in the performance of potential technologies. A robust design process is introduced to account for this uncertainty in the analysis and optimization of torpedo systems through the combination of Monte Carlo simulation with response surface methodology and metamodeling techniques. Additionally, various other methods that are appropriate to uncertainty analysis are discussed and analyzed. The thesis also advances a new approach towards examining robustness and risk: the treatment of probability of success (POS) as an independent variable. Examining the cost and performance tradeoffs between high and low probability of success designs, the decision-maker can make better informed decisions as to what designs are most promising and determine the optimal balance of risk, cost, and performance. Finally, the thesis examines the use of non-dimensionalization of parameters for torpedo design. The thesis shows that the use of non-dimensional torpedo parameters leads to increased knowledge about the scaleability of torpedo systems and increased performance of Designs of Experiments. The integration of these ideas concerning tactics, robust design with uncertainty, and non-dimensionalization of torpedo parameters has lead to the development of a general, powerful technique by which torpedo and other undersea weapon systems can be fully optimized, thereby increasing performance and decreasing the total cost of future weapon systems.

The problem of aircraft concept selection has become increasingly difficult in recent years due to changes in the primary evaluation criteria of concepts. In the past, performance was often the primary discriminator whereas modern programs have placed increased emphasis on factors such as environmental impact, economics, supportability, aesthetics, and other metrics. The revolutionary nature of the vehicles required to simultaneously meet these conflicting requirements has prompted a shift from design using historical data regression techniques for metric prediction to the use of sophisticated physics-based analysis tools that are capable of analyzing designs outside of the historical database. The use of optimization methods with these physics-based tools, however, has proven difficult because of the tendency of optimizers to exploit assumptions present in the models and drive the design towards a solution which, while promising to the computer, may be infeasible due to factors not considered by the computer codes. In addition to this difficulty, the number of discrete options available at this stage may be unmanageable due to the combinatorial nature of the concept selection problem, leading the analyst to select a sub-optimum baseline vehicle. Some extremely important concept decisions, such as the type of control surface arrangement to use, are frequently made without sufficient understanding of their impact on the important system metrics due to a lack of historical guidance, computational resources, or analysis tools. This thesis discusses the difficulties associated with revolutionary system design, and introduces several new techniques designed to remedy them. First, an interactive design method has been developed that allows the designer to provide feedback to a numerical optimization algorithm during runtime, thereby preventing the optimizer from exploiting weaknesses in the analytical model. This method can be used to account for subjective criteria, or as a crude measure of un-modeled quantitative criteria. Other contributions of the work include a modified Structured Genetic Algorithm that enables the efficient search of large combinatorial design hierarchies and an improved multi-objective optimization procedure that can effectively optimize several objectives simultaneously. A new conceptual design method has been created by drawing upon each of these new capabilities and aspects of more traditional design methods. The ability of this new technique to assist in the design of revolutionary vehicles has been demonstrated using a problem of contemporary interest: the concept exploration of a supersonic business jet. This problem was found to be a good demonstration case because of its novelty and unique requirements, and the results of this proof of concept exercise indicate that the new method is effective at providing additional insight into the relationship between a vehicle's requirements and its favorable attributes.

The procedure for developing a new product, in general, is as follows. First, the design engineer must have a thorough understanding regarding the encountered problem. And, he must produce some design concepts based on the perceived requirements. Finally, some solutions are then achieved according to the prescribed design concepts. Unfortunately, few researchers have been able to explain, in a specific rather than abstract manner, the process of generating pertinent design concepts. However, this process has to be a very critical link in the chain. Without obtaining a good design concept the entire design procedure will fall, not to mention to find a suitable solution. In this research we use an interesting analogy between the design procedure and the well-familiarized Sun/Water-cycle system, to concretely describe the task of inspiration of innovative concepts particularly in engineering design. The use of this analogy, we believe, will guide engineers to more effectively and more efficiently go through the stages of conceptual design. Consequently, the entire product development time can be reduced.