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A framework for supporting multidisciplinary engineering design exploration and life-cycle design using underconstrained problem solving
- XIU-TIAN YAN, HIROYUKI SAWADA
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The problem investigated in this research is that engineering design decision making can be complicated and made difficult by highly coupled design parameters and the vast number of design parameters. This complication often hinders the full exploration of a design solution space in order to generate optimal design solution. These hindrances result in inferior or unfit design solutions generated for a given design problem due to a lack of understanding of both the problem and the solution space. This research introduces a computational framework of a new algebraic constraint-based design approach aimed at providing a deeper understanding of the design problem and enabling the designers to gain insights to the dynamic solution space and the problem. This will enable designers to make informed decisions based on the insights derived from parameter relationships extracted. This paper also describes an enhanced understanding of an engineering design process as a constraint centered design. It argues that with more effort and appreciation of the benefits derived from this constraint-based design approach, engineering design can be advanced significantly by first generating a more quantitative product design specification and then using these quantitative statements as the basis for constraint-based rigorous design. The approach has been investigated in the context of whole product life-cycle design and multidisciplinary design, aiming to derive a generic constraint-based design approach that can cope with life-cycle design and different engineering disciplines. A prototype system has been implemented based on a constraint-based system architecture. The paper gives details of the constraint-based design process through illustrating a worked real design example. The successful application of the approach in two highly coupled engineering design problems and the evaluation undertaken by a group of experienced designers show that the approach does provide the designers with insights for better exploration, enabled by the algebraic constraint solver. The approach thus provides a significant step towards fuller scale constraint-based scientific design.
In vitro developmental competence of pig nuclear transferred embryos: effects of GFP transfection, refrigeration, cell cycle synchronization and shapes of donor cells
- Yun-Hai Zhang, Deng-Ke Pan, Xiu-Zhu Sun, Guo-Jie Sun, Xiao-Hui Liu, Xiao-Bo Wang, Xing-Hua Tian, Yan Li, Yun-Ping Dai, Ning Li
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The present study was designed to evaluate the feasibility of producing pig transgenic blastocysts expressing enhanced green fluorescent protein (GFP) and to examine the effects of shape and preparation methods of donor cells on in vitro developmental ability of pig nuclear transferred embryos (NTEs). In experiment 1, the effect of GFP transfection on development of pig NTEs was evaluated. The cleavage and blastocyst rates showed no significant difference between NTEs derived from transfected and non-transfected donors. In experiment 2, the effect of different nuclear donor preparation methods on in vitro development of NTEs was examined. The cleavage rate showed no statistically significant differences among three preparation methods. The blastocyst rates of donor cells treated once at −4 °C and those of freshly digested cells were similar to each other (26.3% vs 17.9%). The lowest blastocyst rates (5.88%) were observed when cells cryopreserved at −196 °C were used as donors. In experiment 3, the effect of different cell cycle synchronization methods on the in vitro development potential of pig NTEs was evaluated. The cleavage rate of NTEs derived from cycling cells was much better than that of NTEs derived from serum-starved cells (64.4% vs 50.5%, p < 0.05), but no significant difference was observed between the the blastocyst rates of the two groups. In experiment 4, the effect of different shapes of cultured fibroblast cells on the in vitro development of pig NTEs was examined. The fusion rate for couplets derived from rough cells was poorer than that observed in couplets derived from round smooth cells (47.8% vs 76.8%, p < 0.05). However, there were no significant differences observed in the cleavage rate and blastocyst rate. In conclusion, the present study indicated that (i) refrigerated pig GFP-transfected cells could be used as donors in nuclear transfer and these NTEs could be effectively developed to blastocyst stage; (ii) serum starvation of GFP-transfected cells is not required for preimplantation development of pig NTEs; and (iii) a rough surface of GFP-transfected donor cells affects fusion rate negatively but has no influence on the cleavage rate or blastocyst rate of pig NTEs.
Exploring decisions' influence on life-cycle performance to aid “design for Multi-X”
- JONATHAN C. BORG, XIU-TIAN YAN, NEAL P. JUSTER
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The problem addressed in this paper is that design decisions can have a propagation effect spanning multiple life-phases influencing life-cycle metrics such as cost, time, and quality. It introduces a computational framework of a “Knowledge of life-cycle Consequences (KC) approach” aimed at allowing designers to foresee and explore effectively unintended, solution specific life-cycle consequences (LCCs) during solution synthesis. The paper presents a phenomena model describing how LCCs are generated from two fundamentally different conditions: noninteracting and interacting synthesis decision commitments. Based on this understanding, the KC approach framework has been developed and implemented as a Knowledge-Intensive CAD (KICAD) tool named FORESEE. The framework consists of three frames: an artefact life modelling frame, an operational frame, and an LCC knowledge modelling frame. This paper focuses on the knowledge modelling frame, composed basically of synthesis elements, consequence inference knowledge, and consequence action knowledge. To evaluate the influence of design decision consequences on artefact life-phases, cost, time and quality performance measures are used within the frame. Using these metrics, the life-cycle implications of a decision can be instantly updated and fully appreciated. An evaluation of the approach was carried out by applying FORESEE to thermoplastic component design. The results provide a degree of evidence that the approach integrates the activity of component design synthesis with the activity of foreseeing artefact life issues including fluctuations in life-cycle metrics. This makes the approach fundamentally different from the conventional approach in which first a candidate design solution is generated and then, at a penalty of extra time, an analysis of the solution for conflicts with artefact life issues is carried out. The framework thus provides a significant step towards the realization of a “Design Synthesis for Multi-X” approach to component design, although further work is required to exploit practically its utilization.
Guiding component form design using decision consequence knowledge support
- JONATHAN C. BORG, XIU-TIAN YAN, NEAL P. JUSTER
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This paper describes a generic approach to guiding designers when making decisions during the early stages of design. The objective of the research is to enable designers to foresee unintended life-cycle consequences during mechanical component design. Engineering design is a process of evolving solutions to a design problem through the commitment of decisions. As a designer commits a new design decision, a more concrete design solution is generated. Decisions made can have intended and unintended consequences on the performance of the life phase activities that follow, such as manufacturing, assembly, and disposal. Many existing tools only consider the impact of the design solution on later life-cycle phases when the solution is almost complete. This makes changes expensive and difficult. This paper presents a novel approach to how consequences encountered in down stream life-cycle phases can be brought to the designer's attention early in generation of component form. For this purpose, a knowledge model has been derived from a phenomena model. The phenomena model describes how life-cycle consequences are generated during component synthesis. An insight into the representation of the resultant knowledge model is discussed through examples. The implementation of a prototype Knowledge Intensive CAD tool, entitled FORESEE, aimed at supporting life-oriented, feature-based component synthesis and exploration, is also described. The results of the evaluation of FORESEE with a range of designers show that by using the system designers are motivated to explore alternative design solutions and are able to make more informed design decisions. This highlights that the knowledge structure provides a base for extending feature-based component design to a ‘Design Synthesis for Multi-X’ approach.