| 1. |
- Allison, James, et al.
(författare)
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Aircraft family design using decomposition-based methods
- 2006
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Ingår i: 11th AIAA/ISSMO Multidisciplinary Analysis and Optimization Conference. - Reston, Va. : American Institute of Aeronautics and Astronautics, AIAA. - 156347803X ; , s. 606-617
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Konferensbidrag (refereegranskat)abstract
- This paper explores the use of decomposition-based methods for aircraft family design. The traditional approach in multidisciplinary design optimization is to decompose a problem along disciplinary lines. For aircraft family design problems, a more natural approach is decomposition by individual aircraft. This decomposition facilitates the concurrent development of several aircraft variants, providing substantial autonomy to individual aircraft development programs. Two decomposition-based methods are applied to the aircraft family problem: collaborative optimization and analytical target cascading. This paper marks the beginning of a collaborative effort to clarify the distinctions between these two methods, and to identify how these differences impact the relative performance and applicability of these methods. Initial product family results illustrate how decomposition-based methods can be applied to the aircraft family problem.
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| 2. |
- Allison, James, et al.
(författare)
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Analytical target cascading in aircraft design
- 2006
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Ingår i: 44th AIAA Aerospace Sciences Meeting and Exhibit. - Reston, Va. : American Institute of Aeronautics and Astronautics, AIAA. - 1563477955 ; , s. 16112-16120
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Konferensbidrag (refereegranskat)abstract
- Analytical Target Cascading (ATC) is a product development tool that computes component design specifications such that the final system design is consistent and meets design targets. ATC is useful for complex product design that must be approached by decomposition, and facilitates concurrent design activities. While ATC has been applied successfully to automotive design, this article introduces the application of ATC to aircraft design, and discusses how it can be congruent with current design practice. ATC is used to solve an aircraft design problem where several flight regimes are considered separately. ATC can be used to balance low-fidelity system analysis and component-level multidisciplinary design optimization (MDO) activities. Finally, ATC may be used to coordinate overall aircraft design, with MDO employed to solve tightly coupled disciplinary problems that exist within ATC elements.
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| 3. |
- Allison, James, et al.
(författare)
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On the impact of coupling strength on complex system optimization for single-level formulations
- 2005
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Ingår i: Proceedings of the ASME Design Engineering Technical Conferences and Computers and Information in Engineering Conference - 2005. - New York : American Society of Mechanical Engineers. - 079184739X ; , s. 265-275
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Konferensbidrag (refereegranskat)abstract
- Design of modern engineering products requires complexity management. Several methodologies for complex system optimization have been developed in response. Single-level strategies centralize decision-making authority, while multi-level strategies distribute the decision-making process. This article studies the impact of coupling strength on single-level Multi-disciplinary Design Optimization formulations, particularly the Multidisciplinary Feasible (MDF) and Individual Disciplinary Feasible (IDF) formulations. The Fixed Point Iteration solution strategy is used to motivate the analysis. A new example problem with variable coupling strength is introduced, involving the design of a turbine blade and a fully analytic mathematical model. The example facilitates a clear illustration of MDF and IDF and provides an insightful comparison between these two formulations. Specifically, it is shown that MDF is sensitive to variations in coupling strength, while IDF is not
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| 4. |
- Allison, James T., et al.
(författare)
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On selecting single-level formulations for complex system design optimization
- 2007
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Ingår i: Journal of mechanical design (1990). - : ASME International. - 1050-0472 .- 1528-9001. ; 129:9, s. 898-906
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Tidskriftsartikel (refereegranskat)abstract
- Design of complex products with several interacting subsystems or disciplinary analyses poses substantive challenges to both analysis and optimization, necessitating specialized solution techniques. A product or system may qualify as complex due to large scale or due to strong interactions. Single-level strategies for complex system optimization centralize decision-making authority, while multilevel strategies distribute the decision-making process. This article studies important differences between two popular single-level formulations: multidisciplinary feasible (MDF) and individual disciplinary feasible (IDF). Results presented aim at aiding practitioners in selecting between formulations. Specifically, while IDF incurs some computational overhead, it may find optima hidden to MDF and is more efficient computationally for strongly coupled problems; further MDF is sensitive to variations in coupling strength, while IDF is not. Conditions that lead to failure of MDF are described. Two new reproducible design examples are introduced to illustrate these findings and to provide test problems for other investigations
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| 5. |
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| 6. |
- Allison, James T., et al.
(författare)
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Optimal partitioning and coordination decisions in decomposition-based design optimization
- 2009
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Ingår i: Journal of mechanical design (1990). - : ASME International. - 1050-0472 .- 1528-9001. ; 131:8, s. 0810081-0810088
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Tidskriftsartikel (refereegranskat)abstract
- The solution of complex system design problems using decomposition-based optimization methods requires determination of appropriate problem partitioning and coordination strategies. Previous optimal partitioning techniques have not addressed the coordination issue explicitly. This article presents a formal approach to simultaneous partitioning and coordination strategy decisions that can provide insights on whether a decompositionbased method will be effective for a given problem. Pareto-optimal solutions are generated to quantify tradeoffs between the sizes of subproblems and coordination problems as measures of the computational costs resulting from different partitioning and coordination strategies. Promising preliminary results with small test problems are presented. The approach is illustrated on an electric water pump design problem
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| 7. |
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| 8. |
- Chan, Kuei-Yuan, et al.
(författare)
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Propagation of Uncertainty in Optimal Design of Multilevel Systems : Piston-Ring/Cylinder-Liner Case Study
- 2004
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Ingår i: 2004 SAE world congress. - Warrendale, Pa : Society of Automotive Engineers, Incorporated.
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Konferensbidrag (refereegranskat)abstract
- This paper proposes an approach for optimal design of multilevel systems under uncertainty. The approach utilizes the stochastic extension of the analytical target cascading formulation. The reliability of satisfying the probabilistic constraints is computed by means of the most probable point method using the hybrid mean value algorithm. A linearization technique is employed for estimating the propagation of uncertainties throughout the problem hierarchy. The proposed methodology is applied to a piston-ring/cylinder-liner engine subassembly design problem. Specifically, we assess the impact of variations in manufacturing-related properties such as surface roughness on engine attributes such as brake-specific fuel consumption. Results are compared to the ones obtained using Monte Carlo simulation.
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| 9. |
- Cooper, Adam B., et al.
(författare)
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A Dual-Use Enterprise Context for Vehicle Design and Technology Valuation
- 2004
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Ingår i: 2004 SAE world congress. - Warrendale, Pa : Society of Automotive Engineers, Incorporated.
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Konferensbidrag (refereegranskat)abstract
- Developing a new technology requires decision-makers to understand the technology's implications on an organization's objectives, which depend on user needs targeted by the technology. If these needs are common between two organizations, collaboration could result in more efficient technology development. For hybrid truck design, both commercial manufacturers and the military have similar performance needs. As the new technology penetrates the truck market, the commercial enterprise must quantify how the hybrid's superior fuel efficiency will impact consumer purchasing and, thus, future enterprise profits. The Army is also interested in hybrid technology as it continues its transformation to a more fuel-efficient force. Despite having different objectives, maximizing profit and battlefield performance, respectively, the commercial enterprise and Army can take advantage of their mutual needs. Developing the new technology in a dual-use context allows the Army to leverage the design and production capabilities of the commercial enterprise, while the enterprise increases its hybrid production volume with military trucks during the low demand phase of hybrid market penetration. This article describes the valuation of hybrid technology from both the enterprise and military perspectives using a previously developed enterprise decision model, which utilizes comprehensive vehicle simulation to drive decision-making. The enterprise is represented in a mathematical formulation that simultaneously optimizes initial vehicle design, product pricing, operating costs associated with capacity investment and design decisions, and the value created by the new products. The application of hybrid technology in the medium truck market illustrates the impact of dual-use decision-making on the commercial enterprise and satisfaction of military performance targets.
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| 10. |
- Etman, L.F.P., et al.
(författare)
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Coordination specification for distributed optimal system design using the chi language
- 2002
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Ingår i: A collection of technical papers. - Reston, Va. : American Institute of Aeronautics and Astronautics, AIAA. - 1563475502
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Konferensbidrag (refereegranskat)abstract
- Coordination plays a key role in solving decomposed optimal system design problems. Several coordination strategies have been proposed in the multidisciplinary optimization (MDO) literature. They are usually presented as a sequence of statements: the parallel nature of the multidisciplinary subproblems is often either not addressed or only briefly mentioned. However, a more formal description of the concurrency in the coordination is essential, in particular for large and non-hierarchic coordination architectures. This paper proposes to use concepts from communicating sequential processes (CSPs) developed in concurrency theory. CSPs allow the description of the MDO coordination as a number of parallel processes that operate independently and communicate with each other synchronously over pre-defined channels. For this purpose, we introduce elements of the language chi, a CSP-based language that contains data types such as reals, arrays, lists and tuples. The accompanying software tool set that enables the execution of a chi specification has been extended with a Python interface so that function calls to external software can be carried out. Through this interface, chi has been coupled with Matlab to run coordination specifications of distributed optimal system design problems on single or multiple parallel computers. An optimal design example is used to illustrate this. It is concluded that the use of a CSP-based language such as chi for coordinating the solution of MDO problems is quite promising
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