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10th ACM SIGSOFT International Workshop on Automating TEST Case Design, Selection, and Evaluation (A-TEST)

作者： Turlea, Ana Univ Bucharest Fac Math & Comp Sci Bucharest Romania Univ Bucharest ICUB Bucharest Romania

ISBN: (纸本)9781450368506

Finite state machines (FSMs) are widely used in test data generation approaches. An extended finite state machine (EFSM) extends the FSM with memory (context variables), guards for each transition and assignment operations. In FSMs all paths are feasible, but the existence of context variables combined with guards in EFSMs can lead to infeasible paths. Using EFSMs in test data generation, we are dealing with feasibility problems. This paper presents a test suite generation algorithm for EFSMs. The algorithm produces a set of feasible transition paths (test cases) that cover all transitions using NSGA-III. We also measure the similarities between test cases from the generated test suite.

关键词： genetic algorithms search based testing test case generation model based testing extended finite state machines multi objective genetic algorithm nsga-iii

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Effect of Nonuniform Tip Clearance on the Performance of Transonic Axial Compressors

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JOURNAL OF PROPULSION AND POWER 2018年第3期34卷 808-818页

作者： Li, Zhihui Liu, Yanming Ji, Lucheng Agarwal, Ramesh K. Beijing Inst Technol Sch Aerosp Engn Beijing 100081 Peoples R China Washington Univ Dept Mech Engn & Mat Sci St Louis MO 63130 USA

Tip leakage significantly affects the axial-compressor performance (i.e., its pressure ratio, peak efficiency, and surge margin). The size of the clearance is one of the most important parameters in compressor design. Generally, the tip clearance is uniform from the leading edge to the trailing edge of the compressor-blade section at the tip. In this paper, the effect of chordwise nonuniform tip clearance on the axial-compressor performance is investigated. In addition, the optimum distribution of clearance size is obtained by employing a surrogate model in conjunction with a multi-objective genetic algorithm for optimization. It is shown that the nonuniform tip clearance can effectively reduce the leakage mass-flow rate and eliminate the flow separation, thus enhancing the overall performance of the compressor. Based on the results of the sensitivity analysis, it is found that the changes in clearance size near the trailing edge of the blade tip contribute more toward the improvement of the compressor efficiency than those obtained by changing the clearance near the leading edge. The Pareto optimal front obtained by employing the multi-objective genetic algorithm shows that the transonic axial compressor with well-designed distributions of tip-clearance size gives 0.64% improvement in peak efficiency and 48.18% enhancement in surge margin.

关键词： Transonic Axial Compressors Trailing Edges Mass Flow Rate multi objective genetic algorithm Surrogate Model Sensitivity Analysis Flow Separation Kriging Model Numerical Simulation Mach Number

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Optimization Using multiple Dominance Criteria for Aerospace Design Under Uncertainty

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AIAA JOURNAL 2018年第12期56卷 4965-4976页

作者： Cook, Laurence W. Jarrett, Jerome P. Univ Cambridge Dept Engn Cambridge CB2 1PZ England

In optimization under uncertainty for aerospace design, statistical moments of the quantity of interest are often treated as separate objectives and are traded off in a multi-objective optimization formulation. However, in many design problems, the tradeoff between statistical moments can be large, and the Pareto front representing this tradeoff can include designs with undesirable behavior, such as being robust but being guaranteed to give a worse performance than another design. When a simulation of a system is computationally expensive, obtaining the full Pareto front is unfeasible, and so spending optimization time obtaining such undesirable designs wastes time that could be spent obtaining more desirable alternatives. As a remedy, an optimization formulation is proposed that can use multiple dominance criteria to avoid generating potentially inferior designs. Various orders of stochastic dominance are considered as criteria to use alongside statistical moment-based Pareto dominance, and it is illustrated how this gives rise to improved designs using a limited computational budget in an acoustic horn design problem and a transonic airfoil design problem.

关键词： Aerospace Designs NACA 0012 Cumulative Distribution Function multi objective genetic algorithm Lift to Drag Ratio Mach Numbers CFD Robust Design Reynolds Averaged Navier Stokes Surrogate Model

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multi-objective Optimization of a Pitch Point Absorber Wave Energy Converter

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WATER 2019年第5期11卷 969页

作者： Alamian, Rezvan Shafaghat, Rouzbeh Safaei, Mohammad Reza Babol Noshirvani Univ Technol Sea Based Energy Res Grp Babol Sar 47148 Iran Ton Duc Thang Univ Inst Computat Sci Div Computat Phys Ho Chi Minh City Vietnam Ton Duc Thang Univ Fac Elect & Elect Engn Ho Chi Minh City Vietnam

In this paper, a pitch point absorber wave energy converter (WEC) is selected in order to be optimized for the wave characteristics of the Caspian Sea. The optimization process is a multi-objective optimization. For achieving the optimal WEC, mean absorbed power should be maximized while the construction cost should be minimized. The submerged surface area of the WEC is selected as a cost parameter. The amount of mean absorbed power depends on the installation site and also the shape of the WEC. For optimizing the shape of the WEC, various shapes are considered which are categorized into three different sections. A multi-objective genetic algorithm is used for optimization of the model, and the NEMOH software is used to simulate the wave-body interaction. The results show that the bottom flat and upside chamfered geometry with X:Y ratio of 10:1 is the best geometry for the desired application. Comparing the results from the final optimized shape with the optimized basic parallelepipedic hull shape reveals that much more extractable power can be achieved with less cost.

关键词： wave energy converter point absorber geometry optimization multi objective genetic algorithm Caspian Sea

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A New Convex Hull, Sliding Window Based Online Adaptation Method

A New Convex Hull, Sliding Window Based Online Adaptation Me...

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3rd IFAC Conference on Embedded Systems, Computational Intelligence and Telematics in Control (CESCIT)

作者： Khosravani, H. Ruano, A. Ferreira, P. M. Univ Algarve Fac Sci & Technol Faro Portugal Univ Lisbon Inst Super Tecn IDMEC Lisbon Portugal Univ Lisbon Fac Ciencias LaSIGE Lisbon Portugal

In any online adaptation scheme, two important phenomena should be taken into consideration;parameter shadowing and parameter interference. To alleviate these problems, in this paper a convex hull, sliding window based online adaptation method for fixed-structure Neural Networks is proposed. The method is capable of dealing with the two phenomena, presenting better results than known alternatives. An analysis of the real-time run time and memory consumption of the algorithm demonstrates that it can be used for real-time applications. (C) 2018, IFAC (International Federation of Automatic Control) Hosting by Elsevier Ltd. All rights reserved.

关键词： Convex Hull multi objective genetic algorithm Online Adaptation Process Radial Basis Function Neural Networks Time Series Models

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Design and Optimisation of a 20kW Horizontal Axis Wind Turbine using HARP_Opt*

Design and Optimisation of a 20kW Horizontal Axis Wind Turbi...

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IEEE International Conference on Power and Energy Systems (ICPES)

作者： Krishneel A Singh Mohammed R Ahmed School of Engineering and Physics The University of the South Pacific Suva Fiji

ISBN: (数字)9781728126586

ISBN: (纸本)9781728126593

The design of a 20 kW horizontal axis small wind turbine was carried out using the analysed wind data and the Weibull parameters of a site in Vanuatu. The airfoils were generated for the 20 kW SWT and optimized using XFOIL. The initial airfoil was parameterized using a 7 th order Bezier curve. Three airfoils with thicknesses of 21%, 14% and 9% were generated for the root region, mid region and the tip region respectively. The performance characteristics were studied and Harp_Opt was used to design and optimize the 20 kW wind turbine. A cut-in wind speed of 2 m/s and a rated wind speed of 10 m/s were shown by the power curve. The annual energy production (AEP) of the designed turbine was calculated to be 66.75 MWh/year with a capacity factor of around 38.1%. Small wind turbines will be ideal for the Pacific Island Countries (PICs) since they can operate at low wind speeds and Reynolds numbers less than 500,000. Using larger commercial turbines are not ideal for the PICs due to frequent cyclones and logistics issues thus a SWT is designed in the present work.

关键词： Horizontal axis wind turbine small wind turbine multi objective genetic algorithm HARP_Opt optimization horizontal axis wind turbine Wind Energy Conversion Systems wind speed PICs Weibull parameters multi-objective evolutionary algorithm Reynolds number Standard Widget Toolkit Airfoils Wind data

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Design of a leading edge morphing based on compliant structures for a twin-prop regional aircraft

Design of a leading edge morphing based on compliant structu...

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AIAA/AHS Adaptive Structures Conference, 2018

作者： De Gaspari, A. Gilardelli, A. Ricci, S. Airoldi, A. Moens, F. Department of Aerospace Science and Technology Politecnico di Milano Via La Masa 34 Milano20156 Italy Aerodynamics Aeroelasticity and Acoustcis Department ONERA The French Aerospace Lab 8 rue des vertugadins Meudon92190 France

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Weighted Gradient-Enhanced Kriging for High-Dimensional Surrogate Modeling and Design Optimization

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AIAA JOURNAL 2017年第12期55卷 4330-4346页

作者： Han, Zhong-Hua Zhang, Yu Song, Chen-Xing Zhang, Ke-Shi Northwestern Polytech Univ Sch Aeronaut Natl Key Lab Sci & Technol Aerodynam Design & Res Youyi West Rd 127POB 754 Xian 710072 Shaanxi Peoples R China Northwestern Polytech Univ Sch Aeronaut Natl Key Lab Sci & Technol Aerodynam Design & Res Youyi West Rd 127POB 120 Xian 710072 Shaanxi Peoples R China

A novel formulation of gradient-enhanced surrogate model, called weighted gradient-enhanced kriging, is proposed and used in combination with the cheap gradients obtained by the adjoint method to ameliorate the curse of dimensionality. The core idea is to build a series of submodels with much smaller correlation matrices and then sum them up with appropriate weight coefficients, aiming to avoid the prohibitive cost associated with decomposing the large correlation matrix of a gradient-enhanced kriging. A self-contained derivation of the proposed method is presented, and then it is verified by surrogate modeling test cases. The present method is integrated into a surrogate-based optimizer and tested for design optimizations. It is further demonstrated for inverse design of a transonic wing, parameterized with a number of design variables in the range from 36 to 108, using Reynolds-averaged Navier-Stokes flow and adjoint solvers. It is observed that, for the wing design with 36 and 54 variables, the weighted and conventional gradient-enhanced kriging are comparable, and both are much more efficient than kriging without using any gradient. For the wing design with 72 and 108 variables, the cost of training a gradient-enhanced kriging increases rapidly and becomes prohibitive. In contrast, the cost of training a weighted gradient-enhanced kriging is kept in an acceptable level, which makes it more practical for higher-dimensional problems.

关键词： Lagrange multipliers Reynolds Averaged Navier Stokes Numerical Simulation Aerodynamic Configurations Sequential Quadratic Programming Hooke Jeeves Pattern Search ANN Aircraft Configurations multi objective genetic algorithm Mathematical Models

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Comparison of Optimization Strategies for High-Lift Design

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JOURNAL OF AIRCRAFT 2017年第2期54卷 642-658页

作者： Iannelli, Pierluigi Moens, Frederic Minervino, Mauro Ponza, Rita Benini, Ernesto Ctr Italiano Ric Aerosp Fluid Mech Dept Aerodynam Technol & Icing Lab I-81043 Capua Italy Off Natl Etud & Rech Aerosp Appl Aerodynam Dept F-92190 Meudon France Piaggio Aero Ind Res & Dev Dept I-17038 Villanova Dalbenga Italy Ctr Italiano Ric Aerosp Fluid Mech Dept Multidisciplinary Anal & Design Lab I-81043 Capua Italy Univ Padua Dept Ind Engn I-35131 Padua Italy

The design of high-lift systems represents a challenging task within the aerospace community, being a multidisciplinary, multi-objective, and multipoint problem. The Design, Simulation and Flight Reynolds Number Testing for Advanced High-Lift Solution project, funded by the European Commission under the Seventh Framework Programme, aimed at improving the aerodynamics of high-lift systems by developing, in a coordinated approach, both efficient numerical design strategies and measurement techniques for cryogenic conditions. Within the Design, Simulation and Flight Reynolds Number Testing for Advanced High-Lift Solution project, different partners used several numerical automatic optimization strategies for high-lift system design purposes. A realistic multi-objective and multipoint optimization problem was defined and solved by adopting different flow model dimensionality, meshing techniques, geometry parameterization, and optimization strategies. Special attention was devoted to perform a fair comparison of the results, and useful information was obtained about trends, pros, and cons of the approaches used. The outcome of these activities is that an efficient design process can be set up through decoupling of the original multi-objective problem into several, sequential suboptimization processes. Nevertheless, several decoupling possibilities exist, and the most efficient one can be identified only on the bases of preanalysis or preknowledge of the specific problem. Second, the exercise carried out demonstrated the maturity and feasibility of a full three-dimensional automatic high-lift design.

关键词： Aerodynamic Force Coefficients CFD Simulation Aerodynamic Efficiency Flap Deflection Reynolds Averaged Navier Stokes multi objective Evolutionary algorithms multi objective genetic algorithm Two Dimensional Flow Optimization algorithm Navier Stokes Solver

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Optimization of Crossflow Staggered Tube Banks for Prescribed Pressure Loss and Effectiveness

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JOURNAL OF THERMOPHYSICS AND HEAT TRANSFER 2017年第4期31卷 878-888页

作者： Yilmaz, Alper Erdinc, Mehmet Tahir Yilmaz, Tuncay Cukurova Univ Dept Automot Engn TR-01330 Adana Turkey Osmaniye Korkut Ata Univ Dept Mech Engn TR-80000 Osmaniye Turkey

For many applications, it is important to transfer a given amount of heat with minimum possible volume of heat exchanger for a given pressure loss and effectiveness. In this study, optimum design of crossflow staggered tube banks for prescribed pressure loss and effectiveness is carried out. For this purpose, the method of Gnielinski-Gaddis is used for the calculation of heat transfer coefficient and pressure loss in tube banks. By prescribing the tube diameter, heat exchanger effectiveness, and pressure loss of the heat exchanger, the pitch length and tube number in the flow direction are determined for the condition of the maximum heat flow per heat exchanger volume. For a given value of total heat to be transferred, the length, height, and width of the heat exchanger can be determined by the equations that are derived using appropriate dimensionless numbers.

关键词： Logarithmic Mean Temperature Difference Heat Exchangers Flow Conditions Finite Volume Method multi objective genetic algorithm Mass Flow Rate Specific Heat Capacity Inlet Temperature Wall Temperature Natural Convection

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