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Geometric Approach to Spacecraft Attitude Control Using Magnetic and Mechanical Actuation

JOURNAL OF GUIDANCE CONTROL AND DYNAMICS 2010年第2期33卷 590-595页

作者： Forbes, James Richard Damaren, Christopher John Univ Toronto Inst Aerosp Studies Toronto ON M3H 5T6 Canada

IT IS well known that spacecraft in low Earth orbit can generate control torques via the interaction of the Earth's geomagnetic field and onboard magnetic dipole moments (created via current-carrying coils) [1,2]. As mentioned in [3], the major shortcoming of magnetic actuation (as the only onboard actuator) is that control torques can only be applied to the spacecraft in a plane orthogonal to the instantaneous direction of the Earth's magnetic field, which in turn means that the spacecraft is instantaneously underactuated.

关键词： Spacecraft Attitude Linear Quadratic Regulator Magnetic Dipoles Attitude Control System Earth's Magnetic Field Quaternions Earth optimization algorithm Spacecraft Orbits Perigee

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Adjoint-Based Design of Rotors in a Noninertial Reference Frame

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JOURNAL OF AIRCRAFT 2010年第2期47卷 638-646页

作者： Nielsen, Eric J. Lee-Rausch, Elizabeth M. Jones, William T. NASA Langley Res Ctr Computat Aerosci Branch Hampton VA 23681 USA NASA Langley Res Ctr Adv Engn Environm Branch Hampton VA 23681 USA

optimization of rotorcraft flowfields using an adjoint method generally requires a time-dependent implementation of the equations. The current study examines an intermediate approach in which a subset of rotor flowfields are cast as steady problems in a noninertial reference frame. This technique permits the use of an existing steady-state adjoint formulation with minor modifications to perform sensitivity analyses. The formulation is valid for isolated rigid rotors in hover or where the freestream velocity is aligned with the axis of rotation. Discrete consistency of the implementation is demonstrated by using comparisons with a complex-variable technique, and a number of single- and multipoint optimizations for the rotorcraft figure of merit function are shown for varying blade collective angles. Design trends are shown to remain consistent as the grid is refined.

关键词： Rotorcraft Simulations Reynolds Averaged Navier Stokes Aerodynamic Coefficients Upwind Scheme Poisson's Ratio Camber Turbulence Models Euler Equations Transonic Flow optimization algorithm

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Bodies Having Minimum Pressure Drag in Supersonic Flow: Investigating Nonlinear Effects

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JOURNAL OF AIRCRAFT 2010年第4期47卷 1451-1454页

作者： Palaniappan, Karthik Jameson, Antony Stanford Univ Dept Aeronaut & Astronaut Stanford CA 94305 USA

One of the classic research problems in supersonic flight has been that of finding two-dimensional and axisymmetric profiles that have minimum pressure drag in supersonic flow. The two-dimensional sections are used as wing-profile sections, and the axisymmetric profiles are useful in that the distribution of the cross-sectional area is made to follow the optimum distribution (the area rule). This problem becomes redundant without suitable constraints. The minimum drag shape is a flat plate in two-dimensional flow and a needle-like profile in axisymmetric flow. However, recent advances in computational fluid dynamics and aerodynamic shape optimization have made it possible for this problem to be analyzed using a nonlinear flow model.

关键词： Aerodynamic Shape optimization Two Dimensional Flow optimization algorithm Supersonic Flight Pressure Coefficient Computational Fluid Dynamics Flow Equations Astronautics Aeronautics

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Hybrid Evolutionary algorithm for the optimization of Interplanetary Trajectories

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JOURNAL OF SPACECRAFT AND ROCKETS 2009年第2期46卷 365-372页

作者： Sentinella, Matteo Rosa Casalino, Lorenzo Politecn Torino Dipartimento Energet I-10129 Turin Italy

A hybrid evolutionary algorithm is applied to the design of interplanetary trajectories with multiple impulses and gravity assists. The optimization procedure runs three different optimizers based on genetic algorithms, differential evolution, and particle swarm optimization "in parallel";the algorithms, which can also he employed separately, are used synergistically here by letting the best individuals, found by each-algorithm, migrate to the others at prescribed intervals. A comparison with the results presented In recent literature, which state that differential evolution is well suited to deal with this kind of problem, is carried out. The performance of the hybrid optimizer is comparable to that of differential evolution in terms of computational time and function evaluations when problems with a reduced number of variables are considered. The hybrid optimizers may instead exhibit better performance when more complex problems are dealt with. The results also show that the algorithm performance is remarkably improved by introducing a "mass mutation' operator to avoid premature converge nee to suboptimal solutions and by means of a particular choice of the variables to describe the trajectory.

关键词： Particle Swarm optimization Interplanetary Trajectories Saturn Genetic algorithm Cassini Mission Orbital Period Lambert's Problem optimization algorithm Deep Space Maneuver Artificial Neural Network

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Computational optimization, modelling and simulation–a paradigm shift

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Procedia Computer Science 2010年第1期1卷 1297-1300页

作者： Xin-She Yang Slawomir Koziel Department of Engineering University of Cambridge Trumpington Street Cambridge CB2 1PZ UK Engineering Optimization and Modeling Center School of Science and Engineering Reykjavik University 101 Reykjavik Iceland

Computational optimization forms an integrated part of modern computational science. Any good design should intend to achieve certain optimality, though optimal solutions are often difficult to find in practice since uncertainty and nonlinearity always present in almost all real-world problems. As resources, time and money are always limited, optimization becomes even more important in practice. This workshop on Computational optimization, Modelling and Simulation (COMS 2010) at ICCS 2010 will summarize the latest developments of optimization and modelling and their applications in science, engineering and industry

关键词： algorithm Black-box modelling Computational optimization Derivative-free method optimization algorithm Modelling Nonlinear optimization Surragate-based optimization Simulation

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Toward Adaptive Ant Colony algorithm

Toward Adaptive Ant Colony Algorithm

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2010 International Conference on Measuring Technology and Mechatronics Automation(ICMTMA 2010)(2010年检测技术与机电自动化国际会议)

作者： Mei-lan Chen Information and Educational Technology Center Foshan University Foshan528000 China

ISBN: (纸本)9781424450015;9780769539621

On the basis of author's former work, this paper presents an improved ant colony algorithm, namely adaptive ant colony algorithm. In the proposed algorithm, the value of evaporation rate p is adaptively changed and a minimum value pain is assigned. Thereby, the evaporation rate p is under control and will never be reduced to O. Then the paper applies the proposed algorithm to grid task scheduling. Comparing experimental results with the original algorithm show that the proposed algorithm is more efficient both in task scheduling efficiency and resource load.

关键词： ant colony optimization algorithm grid computing task schedulling

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Path-Planning with Avoidance Using Nonlinear Branch-and-Bound optimization

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JOURNAL OF GUIDANCE CONTROL AND DYNAMICS 2009年第2期32卷 384-394页

作者： Eele, Alison Richards, Arthur Univ Bristol Dept Aerosp Engn Bristol BS8 1TR Avon England

This paper describes a novel method for finding optimal trajectories for a vehicle constrained to avoid fixed obstacles. The key property of the method is that it provides globally optimal solutions while retaining the full nonlinear dynamics model. Applications for the method include guidance of unmanned aerial vehicles, air traffic control,and robot path planning. The core concept is the direct application of branch-and-bound optimization to find guaranteed, globally optimal solutions to nonconvex problems. The method tailors the branch-and-bound approach specifically for avoidance problems by exploiting two new ideas: first, using a geometric branching strategy based on the decision between passing an obstacle clockwise or counterclockwise;and second, solving the resulting subproblems by constructing simple solutions on each chosen "side" and using them to initialize an interior-point optimization. The algorithm is refined by comparing nine geometric branching strategies. The solution time of the method depends on the choice of branching strategy, which determines how the solution tree is explored. A good strategy is one requiring fewer tree branches to be enumerated before the global optimal is found. The best of these branching strategies has been compared with an existing mixed-integer linear programming approach and demonstrated a significant improvement on mixed-integer linear programming solve times.

关键词： Path Planning Mixed Integer Linear Programming Nonlinear Dynamics Uninhabited Aerial Vehicle Obstacle Avoidance Branch and Bound algorithm Air Traffic Management Air Traffic Control optimization algorithm Vehicle Trajectories

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optimization of Nonlinear Lateral Characteristic of Lifting-Body Type Reentry Vehicle

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JOURNAL OF AEROSPACE COMPUTING INFORMATION AND COMMUNICATION 2009年第3期6卷 239-255页

作者： Jeong, Shinkyu Suzuki, Kunihiro Obayashi, Shigeru Kurita, Mitsuru Tohoku Univ Inst Fluid Sci Aoba Ku Sendai Miyagi 9808577 Japan Japan Aerosp Explorat Agcy Inst Aerosp Technol Tokyo 1828622 Japan

The nonlinear lateral characteristics of a lifting-body type reentry vehicle were improved by applying efficient optimization techniques to determine the optimum configuration. First, the causes for the nonlinear lateral characteristics were investigated by computational fluid dynamics analysis. The results indicated that fins mounted on the Japan Aerospace Exploration Agency's baseline lifting-body configuration cause unsymmetrical development of vortices and result in nonlinear lateral characteristics. An efficienta* optimization algorithm, called efficient global optimization for multiobjective problems, was adopted to improve these nonlinear lateral characteristics. Efficient global optimization for multiobjective problems predicts potential optimum solutions based on the probability estimated by the Kriging model. The computational time for optimization was markedly reduced owing to use of the Kriging model. Further investigations were also performed to determine the effects of the upswept upper-aft and swept-back fin angles. The results indicated that the swept-back fin angle is an important factor controlling the lateral characteristics of the lifting-body type reentry vehicle.

关键词： Reentry Vehicles Lifting Body Kriging Model Vortices CFD Analysis Japan Aerospace Exploration Agency optimization algorithm Angle of Attack Surface Modeling Aerodynamic Characteristics

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optimization of Flapping Motion Parameters for Two Airfoils in a Biplane Configuration

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JOURNAL OF AIRCRAFT 2009年第2期46卷 583-592页

作者： Kaya, Mustafa Tuncer, Ismail H. Jones, Kevin D. Platzer, Max F. Middle E Tech Univ Dept Aerosp Engn TR-06531 Ankara Turkey USN Postgrad Sch Dept Mech & Astronaut Engn Monterey CA 93943 USA

Flapping motion parameters of airfoils in a biplane configuration are optimized for maximum thrust and/or propulsive efficiency. Unsteady, viscous flowfields over airfoils flapping in a combined plunge and pitch are computed with a parallel flow solver on moving and deforming overset grids. The amplitudes of the sinusoidal pitch and plunge motions and the phase shift between them are optimized for a range of flapping frequencies. A gradient-baseda* optimization algorithm is implemented in a parallel computing environment. The deforming overset grids employed remove the restriction on the flapping motion of airfoils, and improve the optimization results obtained earlier. In the Strouhal number range 0.17 < Sr < 0.25, an airfoil in a biplane configuration produces more thrust than a single airfoil. Yet, at a higher Strouhal number, the airfoil in a biplane configuration produced less thrust at a significantly lower efficiency than a single flapping airfoil.

关键词： Biplane Flapping Airfoil Propulsive Efficiency Flapping Frequency Strouhal Number Separated Flows Parallel Computing Environment optimization algorithm Aerodynamic Performance Freestream Mach Number

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Airspace Sector Redesign Based on Voronoi Diagrams

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JOURNAL OF AEROSPACE COMPUTING INFORMATION AND COMMUNICATION 2009年第12期6卷 624-634页

作者： Xue, Min UC Santa Cruz Moffett Field CA 94035 USA

Dynamic resectorization is a promising concept to accommodate the increasing and fluctuating demands of flight operations in the National Airspace System. At the core of dynamic resectorization is finding an optimal sectorization. Finding such an optimal sectorization is challenging, because it mixes the graph partition problem and non-deterministic polynomial-time-hard optimization problem. This paper revisits Voronoi diagrams and genetic algorithms, and proposes a strategy that combines these algorithms with the iterative-deepening algorithm. Voronoi diagrams accomplish the graph partition, which then needs to be optimized. By defining a multi-objective cost, the combination of the genetic algorithm and iterative deepening algorithm solves the optimization problem. Experimental results show that this method can accomplish sector design by setting an appropriate cost. Without a need of clustering, this method can capture the dominant flow, which is one of the major concerns in sector design. The design can have balanced aircraft count and low coordination. If the capacity is defined and incorporated into the cost, the sectorization will lead to a design with increased capacity. The whole process can be finished within a feasible time period without the need for parallel schemes.

关键词： Airspace Region Aircraft Situation Display to Industry Genetic algorithm Current Flight Plan Future Air Traffic Management Concepts Evaluation Tool optimization algorithm Flight Tracking Computing Probability Distribution Machine Learning

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