The design of robust time-delay and saturating controllers based on the range of expected variation of uncertain parameters from their nominal values is investigated. A minimax optimization problem is formulated with ...
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The design of robust time-delay and saturating controllers based on the range of expected variation of uncertain parameters from their nominal values is investigated. A minimax optimization problem is formulated with the objective of minimizing the maximum value of the cost function over the range of the uncertain parameter. By the adoption of the residual energy as the cost function, the optimization problem formulation is simple because it requires only one equation that is used both as the cost function and constraint. To expedite the optimization process, equations are derived for the gradient of the cost and constraint functions with respect to the parameters of the controller. The proposed technique is illustrated on two examples. The first is a spring-mass-dashpot and the second is the two-mass-spring benchmark problem.
Presents a study which analyzed the configuration design sensitivity for dynamic systems using computer-aided design (CAD)-based velocity field. Parameterization and computation of design velocity field with CAD; Conf...
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Presents a study which analyzed the configuration design sensitivity for dynamic systems using computer-aided design (CAD)-based velocity field. Parameterization and computation of design velocity field with CAD; Configuration design sensitivity analysis of Eigenvalue problems; Numerical examples.
The paper deals with the optimum kinematic synthesis and analysis of the five-link independent suspension system (also known as "multilink" suspension, mechanism commonly symbolized 5S-5S). The synthesis goa...
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The paper deals with the optimum kinematic synthesis and analysis of the five-link independent suspension system (also known as "multilink" suspension, mechanism commonly symbolized 5S-5S). The synthesis goal is fulfilling a minimum variation of the wheel track, toe angle and camber angle during jounce and rebound of the wheel. Two solutions obtained by synthesis are analyzed and compared to an existing solution, and the displacement, velocity and acceleration of the wheel carrier relative to the car body are determined, together with the variation of the momentary screw axis and the rear axle roll-center height. Both the kinematic synthesis and the analysis are performed in a simplified, easy to program manner, using a fictitious mechanism that has all the links dismounted from their joints. (C) 2002 Elsevier Science Ltd. All rights reserved.
A method of damage detection for composite plates using Lamb waves and a projection genetic algorithm is investigated in this study. This method first formulates the damage detection as an optimization problem of mini...
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A method of damage detection for composite plates using Lamb waves and a projection genetic algorithm is investigated in this study. This method first formulates the damage detection as an optimization problem of minimizing the error between the measured and calculated surface displacement response derived from Lamb waves. The calculated response is obtained by using the strip element method with the trial crack parameters (location, size). Then a projection genetic algorithm is used to solve the optimization problem and thus identify the actual crack parameters. The projection genetic algorithm is developed from the hybridization of the modified micro-genetic algorithm with a projection operator. It has an excellent convergence performance, taking only 9.9 similar to 14.2% of the number of function evaluations required by the conventional micro-genetic algorithm to obtain the global optima for six benchmark functions. Numerical examples are presented to verify the proposed method for detection of cracks inside composite plates. The maximal error of detected crack parameters is -4.3% for four simulated cases, which is achieved by running only 60 generations of projection genetic algorithm.
作者：
Lucia, DJPachter, MBeran, PSUSAF
Inst Technol Dept Aeronaut & Astronaut Wright Patterson AFB OH 45433 USA USAF
Inst Technol Dept Elect Engn Wright Patterson AFB OH 45433 USA USAF
Res Lab Air Vehicles Directorate Wright Patterson AFB OH 45433 USA
The use of proper orthogonal decomposition-based reduced-order computational fluid dynamics models for multidisciplinary optimization are investigated. An open-loop optimal control problem is solved concerning the reg...
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The use of proper orthogonal decomposition-based reduced-order computational fluid dynamics models for multidisciplinary optimization are investigated. An open-loop optimal control problem is solved concerning the regulation of a rocket engine thrust profile. The control synthesis uses a numerical flowfield solver as the plant model. Controllers are synthesized using both the full-order nonlinear fluid dynamics, which serves as a truth model, and a reduced-order model of the flowfield generated via proper orthogonal decomposition. The latter has been successfully applied to reduce the order of both steady and unsteady subsonic flowfield solutions obtained via computational fluid dynamics. Specifically, the application of reduced-order flowfield solvers to a rocket's thrust controller design is explored. A quasi-one-dimensional supersonic convergent-divergent nozzle with varying backpressure is used as a model problem. Treating the nozzle flow as one-dimensional, the reduced-order model is used to synthesize a nonlinear controller that controls thrust by varying nozzle throat area along an ascent trajectory. The performance of the reduced-order controller is quantified.
Describes the inverse transonic airfoil design using parallel simulated annealing and computational fluid dynamics. Categories of problems on the design of transonic airfoil shapes; Implications of computational fluid...
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Describes the inverse transonic airfoil design using parallel simulated annealing and computational fluid dynamics. Categories of problems on the design of transonic airfoil shapes; Implications of computational fluid dynamics; Definition of simulated annealing; Advantages and disadvantages of simulated annealing.
Design parameters of a flight control system are optimized by a probabilistic method. Simulated annealing is applied for the optimization, and the downhill-simplex method is added to generate new design vector candida...
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Design parameters of a flight control system are optimized by a probabilistic method. Simulated annealing is applied for the optimization, and the downhill-simplex method is added to generate new design vector candidates. The cost function to be minimized is chosen as the probability of violating the design criteria, and it is derived by Monte Carlo evaluation that incorporates various uncertainties. Thus, the designed system is robust against these uncertainties. The feasibility of the algorithm is demonstrated by designing a control system for a simplified model. The results show that simulated annealing is more effective than the downhill-simplex method for parameter optimization, and it requires less computational time than the genetic algorithm. The Automatic Landing Flight Experiment unpiloted reentry vehicle provides a second example. Simulated annealing is shown to produce a more robust longitudinal flight control design than that used in the 1996 flight experiment.
Examines the equivalence between the combined approximations (CA) technique and Krylov subspace methods. Combined approximations technique; Preconditioned Krylov subspace connection; Convergence of the CA technique.
Examines the equivalence between the combined approximations (CA) technique and Krylov subspace methods. Combined approximations technique; Preconditioned Krylov subspace connection; Convergence of the CA technique.
A zero flow, fully three-dimensional, variable impedance, rectangular duct aeroacoustics code that spans the frequency spectrum of interest in duct liner research is developed. The governing equations and boundary con...
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A zero flow, fully three-dimensional, variable impedance, rectangular duct aeroacoustics code that spans the frequency spectrum of interest in duct liner research is developed. The governing equations and boundary conditions in the duct are solved numerically using the finite element methodology. The methodology makes use of a state-of-the-art, sparse equation solver to obtain the capability to study high-frequency sound waves that may require millions of grid points for resolution. Noise suppression levels predicted from the code are in excellent agreement with those obtained from mode theory. Tile single-processor performance of the solver, relative to that of the more commonly used band solver, increases with frequency. At a frequency of 17 kHz, the band solver is 4.25 times slower and consumes 2.5 times more memory than the fully sparse equation solver. The duct aeroacoustics code is combined with an optimization algorithm and used successfully to educe the impedance spectrum of a ceramic liner. The primary problem with using the methodology to perform optimization studies at frequencies above 14 kHz is excessive central processor unit time. The results support the recommendation that research be directed toward exploitation of the multiprocessor capability of the solver to further reduce central processor unit time.
作者：
Jin, GFTan, QFTsing Hua Univ
State Key Lab Precis Measurement Technol & Instru Beijing 100084 Peoples R China
In this paper, a part of research findings on Binary Optics in China is briefly introduced, including several algorithms proposed to improve Gerchberg-Saxton algorithm, Yang-Gu algorithm, some new hybrid optimization ...
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ISBN:
(纸本)0819446866
In this paper, a part of research findings on Binary Optics in China is briefly introduced, including several algorithms proposed to improve Gerchberg-Saxton algorithm, Yang-Gu algorithm, some new hybrid optimization algorithms and a precise design method to realize true beam shaping. Some new methods to fabricate continuous-phase binary optical element and several practical applications are also indicated.
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