This paper furthers the development of Evolutionary Computation, specifically Genetic Algorithms (GA's) applied to the waveform design of simultaneously transmitted orthogonal waveforms. The determination of a sui...
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We present a hybrid algorithm that consists of a population based, stochastic, zero-order optimization algorithm and a gradient based optimization algorithm for robust airfoil design optimization. The gradient based o...
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We present a hybrid algorithm that consists of a population based, stochastic, zero-order optimization algorithm and a gradient based optimization algorithm for robust airfoil design optimization. The gradient based optimization algorithm used in the hybrid is to repair solutions (to satisfy the equality constraints) for the problem in contrast to other hybrids where it is usually used to improve the final solution obtained by the stochastic algorithm. approaches involving equality constraints are known to pose difficulties to existing stochastic methods. The inequality constraints in the present stochastic algorithm are handled via the concept of non-dominance, instead of scaling and aggregating the constraint violations. To demonstrate the behavior of the current proposed hybrid algorithm, we present results of two single objective and two multi-objective airfoil design optimization problems. For comparison, a result of an airfoil design using aggregation is included to highlight some of the limitations of aggregation based formulations used in robust design. To improve upon the computational cost for such computationally expensive problems, we have implemented the algorithm to run on multiple processors based on master-slave architecture.
Improving image quality is the backbone of highly competitive display industry. Contemporary video processing system design is a challenging optimization problem. Generally, several video algorithms must be sequential...
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ISBN:
(纸本)3540223436
Improving image quality is the backbone of highly competitive display industry. Contemporary video processing system design is a challenging optimization problem. Generally, several video algorithms must be sequentially applied to real-time video data. Overall image quality depends on the nonlinear interactions between multiple design parameters: variable settings for each module (algorithm), the amount of data being transferred in the video processing chain as well as the order of the cascading modules. Unfortunately, no systematic techniques are currently available to configure the video chain without lengthy trial and error process. We propose a rapid and reliable method for optimization of composite video processing systems based on genetic algorithm coupled with local search heuristics. Video system configuration is evolved toward the best image quality, driven by an objective video quality metric. We analyze several local search approaches, including hill-climbing, simplex and estimation-of-distribution algorithms. Experimental study demonstrates superior performance of memetic strategies over the conventional genetic algorithm. We obtain novel and practical video chain solutions that are typically not attainable by regular design process.
Truss structures are widely employed in the industrialized world. They appear as bridges, towers, roof supports, building exoskeletons or high technology light space structures. This paper investigates the simultaneou...
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ISBN:
(纸本)0791841731
Truss structures are widely employed in the industrialized world. They appear as bridges, towers, roof supports, building exoskeletons or high technology light space structures. This paper investigates the simultaneous size, geometry and topology optimization of real life large truss structures using Genetic Algorithms (GAs) as optimizer and Finite Element Method as analyzer. In general the large truss structures are constructed from the duplication of some basic modules called bays. Thus, the final optimum design may be reached by optimizing the characteristics of the basic bays instead of optimizing the whole structure. Both single and multi-objective functions based on the mass of the structure and the maximum nodal displacement, have been considered as the cost functions. In order to have realistic optimal designs, the cross-sectional areas have been extracted from the standard profiles according to AISC codes and practical conditions are imposed to the bays. The design optimization problem is also constrained by the maximum stress, maximum slenderness ratio and the maximum and minimum cross-sectional area of the truss members. To accommodate all these constraints, two different penalty functions are proposed. The first penalty function considers the normalization of violated constraints with respect to the allowable stress or slenderness ratio. The second penalty function is a constant function, which is used to penalize the violations of the slenderness ratio. Two illustrative examples of realistic planar and space truss structures have been optimized to demonstrate the effectiveness of the proposed methodology.
The concept of simultaneous analysis and design (SAND) is re-visited with two objectives in mind: (i) to propose and evaluate alternate formulations of the structural optimization problem, and (ii) to study implementa...
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Environment impact (EI) is a multi- decision-making, multi-objective and multi-criteria system with uncertainties and ambiguities, and environment impact index (EII) of a chemical compound is difficult to calculate ap...
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Environment impact (EI) is a multi- decision-making, multi-objective and multi-criteria system with uncertainties and ambiguities, and environment impact index (EII) of a chemical compound is difficult to calculate appropriately with traditional *** this paper, fuzzy optimal selection theory based on the concept of relative importance degree is adopted to determine relativity of the degree of environment impact of chemical compounds as EII, and environment impact assessment (EIA) of a chemical process is done with values of compounds EII to select alternatives that cause less pollution to the *** is useful in further process *** paper presents a practical application to the treatment of process condensate in a synthesis ammonia plant to illustrate the procedure, and the calculation result demonstrates the feasibility, practicability, and effectiveness of the suggested method.
The practical use of high-fidelity multidisciplinary optimization techniques in low-boom supersonic business jet designs has been limited because of the high computational cost associated with CFD-based evaluations of...
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ISBN:
(纸本)1563477165
The practical use of high-fidelity multidisciplinary optimization techniques in low-boom supersonic business jet designs has been limited because of the high computational cost associated with CFD-based evaluations of both the performance and the loudness of the ground boom of the aircraft. This is particularly true of designs that involve the sonic boom loudness as either a cost function or a constraint because gradient-free optimization techniques may become necessary, leading to even larger numbers of function evaluations. If, in addition, the objective of the design method is to account for the performance of the aircraft throughout its mission (T/O and landing, climb, acceleration, etc.) while including important multi-disciplinary trade-offs between the relevant disciplines (performance, boom, structures, stability and control, propulsion, etc.) the situation only worsens. In order to overcome these limitations, we propose a hierarchical multi-fidelity design approach where high-fidelity models are only used where and when they are needed to correct the shortcomings of the low-fidelity models. Our design approach consists of two basic components: a multi-disciplinary aircraft synthesis tool (PASS) that uses highly-tuned low-fidelity models of all of the relevant disciplines and computes the complete mission profile of the aircraft, and a hierarchical, multi-fidelity environment for the creation of response surfaces for aerodynamic performance and sonic boom loudness (BOOM-UA) that attempts to achieve the accuracy of an Euler-based design strategy. This procedure is used to create three design alternatives for a Mach 1.6, 6-8 passenger supersonic business jet configuration with a range of 4,500 nmi and with a T/O field length that is shorter than 6,000 ft. Optimized results are obtained with much lower computational cost than the direct, high-fidelity design alternative. The validation of these design results using the high-fidelity model show very good agreeme
The simultaneous design and control of continuous bioprocesses is considered here as a multi-objectiveoptimization problem subject to non-linear differential-algebraic constraints. This type of problem is very challe...
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The simultaneous design and control of continuous bioprocesses is considered here as a multi-objectiveoptimization problem subject to non-linear differential-algebraic constraints. This type of problem is very challenging to solve due to its non-convexity (multi-modality). We present two novel solution approaches based on extensions of an stochastic global optimization method. The robustness and efficiency of these approaches are illustrated with a wastewater treatment plant case study.
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