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Preference-Based Trajectory Generation

JOURNAL OF AEROSPACE COMPUTING INFORMATION AND COMMUNICATION 2009年第3期6卷 142-170页

作者： Lennon, Jamie A. Atkins, Ella M. USN Res Lab Washington DC 20375 USA Univ Michigan Ann Arbor MI 48109 USA

Numerous techniques exist to optimize aircraft and spacecraft trajectories over cost functions that include terms such as fuel, time, and separation from obstacles. Relative weighting factors can dramatically alter solution characteristics, and engineers often must manually adjust either cost weights or the trajectory itself to obtain desirable solutions. Further, when humans and robots work together, or when humans task robots, they may express their performance expectations in a "fuzzy" natural language fashion, or else as an uncertain range of more-or-less acceptable values. This work describes a software architecture which accepts both fuzzy linguistic and hard numeric constraints on trajectory performance and, using a trajectory generator provided by the user, automatically constructs trajectories to meet these specifications as closely as possible. The system respects hard constraints imposed by system dynamics or by the user, and will not let the user's preferences interfere with the system and user needs. The architecture's evaluation agent translates these requirements into cost-functional weights expected to produce the desired motion characteristics. The quality of the resulting full-state trajectory is then evaluated based on a set of computed trajectory features compared to the specified constraints. If constraints are not met, the cost-functional weights are adjusted according to precomputed heuristic equations. Heuristics are not generated in an ad hoc fashion, but are instead the result of a systematic testing of the simulated system under a range of simple conditions. The system is tested in a two degree of freedom (2DOF) linear and a 6DOF nonlinear domain with a variety of constraints and in the presence of obstacles. Results show that the system consistently meets all hard numeric constraints placed on the trajectory. Desired characteristics are often attainable or, in those cases where they are discounted in favor of the hard constraints, fail by

关键词： Transversality Condition Robots Spacecraft Trajectories Software Architecture Satellite Formation Six Degree of Freedom Linear quadratic Regulator sequential quadratic programming Mixed Integer Linear programming Fuzzy Logic

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System protection scheme for mitigation of cascaded voltage collapses

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IET GENERATION TRANSMISSION & DISTRIBUTION 2009年第3期3卷 242-256页

作者： Amraee, Turaj Ranjbar, A. M. Feuillet, R. Mozafari, B. ENSIEG Inst Natl Polytech Grenoble BP 46 F-38402 St Martin Dheres France Sharif Univ Technol Dept Elect Engn Tehran Iran

A system protection scheme is proposed to mitigate cascaded voltage collapses. Based on the post-contingency conditions of either existence or non-existence of an equilibrium solution, and with regard to the stability and security criteria, the proposed scheme finds the optimal set of remedies. The proposed stabilising scheme brings the non-equilibrium post-contingency operating point back inside a stable region, and then passes this point to the securing scheme. Also, to enhance the performance of the stabilising scheme, a sensitivity analysis method is presented to detect the most effective remedies. The proposed securing scheme converts the stable, but insecure operating point, to a secure and stable one. Inclusion of the contingencies in the voltage security problem increases its difficult and, hence, the Benders decomposition method is used for this purpose. Also, a voltage stability indicator is proposed to monitor the available margin to the collapse point. Both the mathematical models of the stabilising and securing schemes are solved using the sequential quadratic programming technique over the IEEE 30-bus and IEEE 118-bus test cases.

关键词： Scheme sequential quadratic programming Workstations Voltage collapse Stabilising stability region REMEDIES Benders decomposition CASING INSPECTION

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Two-Level Multifidelity Design Optimization Studies for Supersonic Jets

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JOURNAL OF AIRCRAFT 2009年第3期46卷 776-790页

作者： Choi, Seongim Alonso, Juan J. Kroo, Ilan M. Stanford Univ Dept Aeronaut & Astronaut Stanford CA 94305 USA

The conceptual/preliminary design of supersonic jet configurations requires multidisciplinary analyses tools, which are able to provide a level of flexibility that permits the exploration of large areas of the design space. High-fidelity analysis for each discipline is desired for credible results;however, the corresponding computational cost can be prohibitively expensive, often limiting the ability to make drastic modifications to the aircraft configuration in question. Our work has progressed in this area, and we have introduced a truly hybrid, multifidelity approach in multidisciplinary analyses and demonstrated, in previous work, its application to the design optimization of a low-boom supersonic business jet. In this paper, we extend our multifidelity approach to the design procedure and present a two-level design of a supersonic business-jet configuration, in which we combine a conceptual low-fidelity optimization tool with a hierarchy of flow solvers of increasing fidelity and advanced adjoint-based sequential quadratic programming optimization approaches. In this work, we focus on the aerodynamic performance aspects alone: no attempt is made to reduce the acoustic signature. The results show that this particular combination of modeling and design techniques is quite effective for our design problem and the ones in general and that high-fidelity aerodynamic shape optimization techniques for complex configurations (such as the adjoint method) can be effectively used within the context of a truly multidisciplinary design environment. Detailed configuration results of our optimizations are also presented.

关键词： Aerodynamic Shape Optimization Aircraft Configurations Camber Aerodynamic Performance Irrotational Flow Thickness to Chord Ratio Sonic Booms sequential quadratic programming Gradient Free Optimization Aspect Ratio

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An optimization method for dynamics of structures with repetitive component patterns

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STRUCTURAL AND MULTIDISCIPLINARY OPTIMIZATION 2009年第6期39卷 557-567页

作者： Perdahcioglu, D. Akcay Ellenbroek, M. H. M. van der Hoogt, P. J. M. de Boer, A. Univ Twente Dept Appl Mech NL-7500 AE Enschede Netherlands

The occurrence of dynamic problems during the operation of machinery may have devastating effects on a product. Therefore, design optimization of these products becomes essential in order to meet safety criteria. In this research, a hybrid design optimization method is proposed where attention is focused on structures having repeating patterns in their geometries. In the proposed method, the analysis is decomposed but the optimization problem itself is treated as a whole. The model of an entire structure is obtained without modeling all the repetitive components using the merits of the Component Mode Synthesis method. Backpropagation Neural Networks are used for surrogate modeling. The optimization is performed using two techniques: Genetic Algorithms (GAs) and sequential quadratic programming (SQP). GAs are utilized to increase the chance of finding the location of the global optimum and since this optimum may not be exact, SQP is employed afterwards to improve the solution. A theoretical test problem is used to demonstrate the method.

关键词： Hybrid design optimization method Repetitive patterns Component mode synthesis Backpropagation neural networks Genetic algorithms sequential quadratic programming

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Domain-Element Method for Aerodynamic Shape Optimization Applied to a Modern Transport Wing

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AIAA JOURNAL 2009年第7期47卷 1647-1659页

作者： Morris, A. M. Allen, C. B. Rendall, T. C. S. Univ Bristol Dept Aerosp Engn Bristol BS8 1TR Avon England

Generic wraparound aerodynamic shape optimization technology is presented and applied to a modern commercial aircraft wing in transonic cruise. The wing geometry is parameterized by a novel domain-element method, which uses efficient global interpolation functions to deform both the surface geometry and corresponding computational fluid dynamics volume mesh. The technique also provides a method that allows geometries to be parameterized at various levels, ranging from global three-dimensional planform alterations to detailed local surface changes. Combining all levels of parameterization allows for free-form design control with very few design variables. The method provides an efficient combined shape parameterization and high-quality mesh deformation technique that is totally independent of mesh type (structured or unstructured). Optimization independence from the flow solver is achieved by obtaining sensitivity information for an advanced gradient-based optimizer by finite differences. The entire optimization suite has also been parallelized to allow optimization with highly flexible parameterization in practical times. Results are presented for highly constrained optimizations of the modern aircraft wing in transonic cruise, using three levels of parameterization (number of design variables) to assess the effect of parameterization level on the optimization. The highest-level optimization results in a totally-shock-free geometry with an associated substantial reduction in drag.

关键词： Aerodynamic Shape Optimization CFD Blended Wing Body Wing Geometry Commercial Aircraft Aerodynamic Performance sequential quadratic programming Numerical Optimization Multivariate Interpolation Shape Optimization

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A modified SQP-filter method for nonlinear complementarity problem

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APPLIED MATHEMATICAL MODELLING 2009年第6期33卷 2890-2896页

作者： Su, Ke Cai, Hui-ping Hebei Univ Coll Math & Comp Baoding 071002 Peoples R China Tongji Univ Dept Math Shanghai 200092 Peoples R China Shijiazhuang Coll Dept Math Shijiazhuang 050035 Peoples R China

The nonlinear complementarity problem can be reformulated as a nonlinear programming. For solving nonlinear programming, sequential quadratic programming (SQP) type method is very effective. Moreover, filter method, for its good numerical results, are extensively studied to handle nonlinear programming problems recently. In this paper, a modified quadratic subproblem is proposed. Based on it, we employ filter technique to tackle nonlinear complementarity problem. This method has no demand on initial point. The restoration phase, which is always used in traditional filter method, is not needed. Global convergence results of the proposed algorithm are established under suitable conditions. Some numerical results are reported in this paper. (C) 2008 Elsevier Inc. All rights reserved.

关键词： Nonlinear complementarity problems Filter method sequential quadratic programming Global convergence

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A novel approach for synthesis of cost-optimal heat exchanger networks

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COMPUTERS & CHEMICAL ENGINEERING 2009年第8期33卷 1363-1370页

作者： Khorasany, R. Mohammadhasani Fesanghary, M. Louisiana State Univ Dept Mech Engn Baton Rouge LA 70808 USA Behbahan Azad Univ Dept Mech Engn Behbahan *** Iran

This study presents a new hybrid methodology for synthesis of cost-optimal heat exchanger networks (HENs). The problem is solved in a two-level approach. The upper level generates the structure of HENs using harmony search (HS) algorithm. To evaluate the minimum cost of each structure, it is sent to the lower level in which the heat load of units and stream-split fractions are optimized by a combination of the HS and sequential quadratic programming (SQP). Based on the cost obtained for each structure HS ranks the HENs and produces new structures until algorithm converges to optimal solution. For validation purpose, three benchmark problems are examined and also a real-world industrial-sized problem is solved to demonstrate the applicability of this method for large-sized problems. The results of this study show that the new approach is able to find more economical networks than those generated by other methods. (C) 2008 Elsevier Ltd. All rights reserved.

关键词： Harmony search Heat exchanger network synthesis Hybridization Optimization sequential quadratic programming

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Optimized compact filtering schemes for computational aeroacoustics

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INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS 2009年第8期60卷 827-845页

作者： Liu Zhanxin Huang Qibai Hu Li Yuan Jixuan Huazhong Univ Sci & Technol Dept Mech Engn Wuhan 430074 Hubei Peoples R China

Spurious waves are inevitably introduced in the simulation of computational aeroacoustics problems by finite difference schemes. Filters are proposed to damp the Spurious waves as soon as they are generated. A family of filtering schemes, both interior and boundary, are optimized in this paper. The transfer functions of the filters are approximated to modified Gaussian functions and sharp spectral cutoffs are obtained. The advanced sequential quadratic pro.-ramming method is employed to get the approximation. Although all of the optimized filters are stable and perform well in the computation, we find that the optimized fourth-order filters are sufficient for different kinds of requirements. The improvements of the accuracy and convenient application of the optimized filters are demonstrated when applied to one- and two-dimensional problems. Copyright (C) 2008 John Wiley & Sons, Ltd.

关键词： filtering schemes compact schemes optimization finite difference sequential quadratic programming computational aeroacoustics

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Global convergence of an SQP method without boundedness assumptions on any of the iterative sequences

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MATHEMATICAL programming 2009年第1期118卷 1-12页

作者： Solodov, Mikhail V. Inst Matematica Pura & Aplicada BR-22460320 Rio De Janeiro Brazil

Usual global convergence results for sequential quadratic programming (SQP) algorithms with linesearch rely on some a priori assumptions about the generated sequences, such as boundedness of the primal sequence and/or of the dual sequence and/or of the sequence of values of a penalty function used in the linesearch procedure. Different convergence statements use different combinations of assumptions, but they all assume boundedness of at least one of the sequences mentioned above. In the given context boundedness assumptions are particularly undesirable, because even for non-pathological and well-behaved problems the associated penalty functions (whose descent is used to produce primal iterates) may not be bounded below for any value of the penalty parameter. Consequently, boundedness assumptions on the iterates are not easily justifiable. By introducing a very simple and computationally cheap safeguard in the linesearch procedure, we prove boundedness of the primal sequence in the case when the feasible set is nonempty, convex, and bounded. If, in addition, the Slater condition holds, we obtain a complete global convergence result without any a priori assumptions on the iterative sequences. The safeguard consists of not accepting a further increase of constraints violation at iterates which are infeasible beyond a chosen threshold, which can always be ensured by the proposed modified SQP linesearch criterion.

关键词： sequential quadratic programming Global convergence Nonsmooth penalty function Linesearch Slater condition

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Leak detection in pipelines by inverse backward transient analysis

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JOURNAL OF HYDRAULIC RESEARCH 2009年第3期47卷 311-318页

作者： Shamloo, Hamid Haghighi, Ali KN Toosi Univ Technol Dept Civil Engn Tehran 19697 Iran

A new method of leak detection in pipelines is introduced based on the inverse transient analysis. The transient state can be initiated in pipes by closing the downstream end valve. The time history of pressure fluctuations is measured at the valve location as a downstream boundary condition. The duration of valve closure is considered long enough to minimize effects of the friction factor and of waterhammer. The numerical modeling of transient analysis in time domain uses the backward Method Of Characteristics (MOC). An inverse problem is applied for leak detection by defining the least-squares criterion objective function. The leak areas at characteristic nodes are considered as decision variables. Leak parameters are determined using the sequential quadratic programming (SQP) method. To eliminate undesirable noisy and uncertainties due to the valve modeling, a method independent of valve type, closure duration and valve operation was considered. Finally, numerical examples are solved based on this method.

关键词： Inverse problem leak detection method of characteristics sequential quadratic programming time domain transient state

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