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Two-dimensional Trajectory Optimization of a Soft Lunar Landing from a Parking Orbit Considering a Landing Site

IFAC Proceedings Volumes 2010年第15期43卷 178-183页

作者： Jong-Sun Ahn Bong-Gyun Park Min-Jea Tahk Space Exploration Engineering Department Korea Advanced Institute of Science and Technology Daejeon Korea Aerospace Engineering Department Korea Advanced Institute of Science and Technology Daejeon Korea (Tel:82-42-350-5758) Aerospace Engineering Department Korea Advanced Institute of Science and Technology Daejeon Korea

Abstract In this paper, minimum-fuel, two-dimensional trajectory optimization from a parking orbit to the desired landing site is presented. The landing site is usually not considered when performing the trajectory optimization. However, to design the precise trajectories to land at the desired site, the landing site has to be considered as the terminal constraint. To convert the trajectory optimization problem into a parameter optimization problem, a pseudospcetral (PS) method is used, and CFSQP is used as a numerical solver. To check that the results obtained are good solutions, the feasibility check is performed.

关键词： Soft landing trajectory optimization legendre pseudospectral method pseudospectral knotting method sequential quadratic programming

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Planning and Management of a Water Reservoir System Due to Expected Climate Changes

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IFAC Proceedings Volumes 1998年第20期31卷 775-780页

作者： P. Fritsch S. Hopfgarten H. Puta Dept. of Automation and Systems Engineering Technical University of Ilmenau P.O. Box 10 05 65 D-98684 Ilmenau Germany

The paper is dedicated to the problem of planning and management of water resources systems. The tasks are formulated as time-discrete dynamic optimal control problem and transformed to a large-scale structured nonlinear optimisation problem with sparse data structures. The solving procedure is an SQP-type algorithm. Two different hydrological scenarios were investigated applying the proposed approach and compared with an existing reservoir management plan. The simulative management in an extraordinary situation was also performed.

关键词： Model-based control sequential quadratic programming Management Planning Water resources system Hydrological changes

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Engine-switching strategies for interplanetary solar-electric-propulsion spacecraft

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JOURNAL OF SPACECRAFT AND ROCKETS 2005年第4期42卷 765-767页

作者： Gao, Y Kluever, CA Univ Missouri Columbia MO 65211 USA

Two simple-switching schemes for interplanetary SEP spacecraft were investigated. The first scheme was found to operate as many engines as possible , whereas the second scheme operates as few engines for given available power. It was found that scheme 2 results in higher initial power , but this system mass penalty is offset by a much larger increase in launch mass. A scheme that operates fewer engines was expected to increase mission reliability by providing spares in case of engine failures.

关键词： Solar Electric Propulsion Spacecrafts NASA Evolutionary Xenon Thruster Propellant Pluto Interplanetary Mission sequential quadratic programming Power Processing Unit Nonlinear programming Electric Propulsion

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An automated approach to magnetic divertor configuration design

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NUCLEAR FUSION 2015年第1期55卷

作者： Blommaert, M. Dekeyser, W. Baelmans, M. Gauger, N. R. Reiter, D. Forschungszentrum Julich Inst Energy & Climate Res Plasma Phys IEK 4 D-52425 Julich Germany Katholieke Univ Leuven Dept Mech Engn B-3001 Louvain Belgium Rhein Westfal TH Aachen Dept Math D-52062 Aachen Germany Rhein Westfal TH Aachen Ctr Computat Engn Sci D-52062 Aachen Germany

Automated methods based on optimization can greatly assist computational engineering design in many areas. In this paper an optimization approach to the magnetic design of a nuclear fusion reactor divertor is proposed and applied to a tokamak edge magnetic configuration in a first feasibility study. The approach is based on reduced models for magnetic field and plasma edge, which are integrated with a grid generator into one sensitivity code. The design objective chosen here for demonstrative purposes is to spread the divertor target heat load as much as possible over the entire target area. Constraints on the separatrix position are introduced to eliminate physically irrelevant magnetic field configurations during the optimization cycle. A gradient projection method is used to ensure stable cost function evaluations during optimization. The concept is applied to a configuration with typical Joint European Torus (JET) parameters and it automatically provides plausible configurations with reduced heat load.

关键词： divertor design edge plasma modelling magnetic topology power deposition sequential quadratic programming parameter optimization

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On-Line Path Generation for Unmanned Aerial Vehicles Using B-Spline Path Templates

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JOURNAL OF GUIDANCE CONTROL AND DYNAMICS 2013年第6期36卷 1642-1653页

作者： Jung, Dongwon Tsiotras, Panagiotis Korea Aerosp Res Inst Taejon 305333 South Korea Georgia Inst Technol Atlanta GA 30332 USA

The problem of generating a smooth reference path, given a finite family of discrete, locally optimal paths, is investigated. A finite discretization of the environment results in a sequence of obstacle-free square cells. The generated path must lie inside the channel generated by these obstacle-free cells, while minimizing certain performance criteria. Two constrained optimization problems are formulated and solved subject to the given geometric (linear) constraints and boundary conditions in order to generate a library of B-spline path templates offline. These templates are recalled during implementation and are merged together on the fly in order to construct a smooth and feasible reference path to be followed by a closed-loop tracking controller. Combined with a discrete path planner, the proposed algorithm provides a complete solution to the obstacle-free path-generation problem for an unmanned aerial vehicle in a computationally efficient manner, which is suitable for real-time implementation.

关键词： UAV Obstacle Avoidance B Splines Path Planning sequential quadratic programming Linear Interpolation Search Algorithm Proximity Sensors Navigation Algorithm Computer Memory

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Three-dimensional ascent trajectory optimization for stratospheric airship platforms in the jet stream

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JOURNAL OF GUIDANCE CONTROL AND DYNAMICS 2007年第5期30卷 1341-1352页

作者： Lee, Sangjong Bang, Hyochoong Korea Aerosp Res Inst Air Vehicle Syst Dept Div Aircraft Taejon 305333 South Korea Korea Adv Inst Sci & Technol Div Aerosp Engn Taejon 305701 South Korea

Full three-dimensional optimal-ascent trajectory design is addressed for a stratospheric airship platform, considering real jet stream and flight constraints. The target airship's equations of motion are first constructed by including wind effects and its inherent features such as added mass and buoyancy effects. For realistic trajectory optimization, additional necessary modeling of the jet stream, aerodynamic force, and thrust are established based on a flight test, wind-tunnel test, and meteorological observation data. In addition, detailed path constraints such as the target airship's performance and local airspace are also accounted for. The sequential quadratic programming approach is employed as a numerical solver for both minimum flight time and minimum-energy performance indices. The solutions obtained satisfy all of the constraints and are largely affected by the jet stream of high wind speed. From the optimization results, the minimum flight time trajectory is recommended due to the low flight performance of the airship in contrast to its huge size and heavy weight.

关键词： Stratospheric Airship Trajectory Optimization Jet Stream Aerodynamic Coefficients Flight Testing Airspace sequential quadratic programming Buoyancy Effects Wind Tunnel Tests Flight Performance

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Structural design optimization of shallow frame structures undergoing large deflections

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AIAA JOURNAL 2004年第12期42卷 2592-2599页

作者： Sedaghati, R Suleman, A Concordia Univ Dept Mech & Ind Engn Montreal PQ H3G 1M8 Canada Univ Victoria Dept Mech Engn Victoria BC V8W 3P6 Canada

An optimization algorithm for structural design against instability is developed for shallow beam structures undergoing large deflections. The algorithm is based on the maximization of the limit load under specified volume constraint. The analysis for obtaining the limit load involves coupling of axial and bending deformations and is based on the nonlinear finite element analysis using the displacement control technique. The optimization is carried out using both the sequential-quadratic-programming (SQP) and optimality-criterion (OC) techniques, and the results are compared. For the SQP technique, the sensitivity derivatives of the critical load factor are calculated using the adjoint method based on the information obtained from the nonlinear buckling analysis. A shallow plane arch illustrates the structural design optimization methodology, and the results are compared with those in the literature. It is shown that a design based on the generalized eigenvalue problem (linear buckling) gives an optimum limit load less than the initial limit load, whereas the optimization using the nonlinear buckling analysis obtains a larger value for the optimum limit load compared to the initial limit load. It has also been demonstrated that the optimum results obtained using OC technique are in good agreement with those obtained through SQP technique. However, the computational time for the OC is significantly lower than that of SQP, which requires search techniques and sensitivity of the limit load for its successful completion and termination.

关键词： Structural Optimization Finite Element Analysis sequential quadratic programming Buckling Analysis Critical Loading Beam (Structures) Lagrange Multipliers Energy Density Young's Modulus Composite Structures

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Reliability Analysis for Multidisciplinary Systems with Random and Interval Variables

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AIAA JOURNAL 2010年第1期48卷 82-91页

作者： Guo, Jia Du, Xiaoping Missouri Univ Sci & Technol Rolla MO 65401 USA

Tremendous efforts have been devoted to developing efficient approaches to reliability analysis for multidisciplinary systems. Most of the approaches are only capable of dealing with random variables modeled by probability distributions. Both random and interval variables, however, may exist in multidisciplinary systems. Their propagation through coupled subsystems make s reliability analysis computationally expensive. In this work, a unified reliability analysis framework is proposed to deal with both random and interval variables in multidisciplinary systems. The framework is an extension of an existing unified uncertainty analysis framework for single-disciplinary problems. The new framework involves probabilistic analysis and interval analysis. Both probabilistic analysis and interval analysis are decoupled from each other and are performed sequentially. The first order reliability method is used for probabilistic analysis. Three supporting algorithms are developed. The effectiveness of the algorithms is demonstrated with a mathematical example and an engineering application.

关键词： Cumulative Distribution Function Aerodynamic Characteristics MDO Search Algorithm High Aspect Ratio Aircraft Wings Finite Element Method Lift Coefficient Shear Strength sequential quadratic programming

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Optimal Power Flow Solution for Bipolar DC Networks Using a Recursive quadratic Approximation

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ENERGIES 2023年第2期16卷

作者： Montoya, Oscar Danilo Gil-Gonzalez, Walter Hernandez, Jesus C. Univ Distrital Francisco Jose de Caldas Fac Ingn Grp Compatibil & Interferencia Electromagnet GCEM Bogota 110231 Colombia Univ Tecnol Bolivar Fac Ingn Lab Inteligente Energia Cartagena 131001 Colombia Univ Tecnol Pereira Dept Elect Engn Pereira 660003 Colombia Univ Jaen Dept Elect Engn Campus Lagunillas S-NEdificio A3 Jaen 23071 Spain

The problem regarding of optimal power flow in bipolar DC networks is addressed in this paper from the recursive programming stand of view. A hyperbolic relationship between constant power terminals and voltage profiles is used to resolve the optimal power flow in bipolar DC networks. The proposed approximation is based on the Taylors' Taylor series expansion. In addition, nonlinear relationships between dispersed generators and voltage profiles are relaxed based on the small voltage voltage-magnitude variations in contrast with power output. The resulting optimization model transforms the exact nonlinear non-convex formulation into a quadratic convex approximation. The main advantage of the quadratic convex reformulation lies in finding the optimum global via recursive programming, which adjusts the point until the desired convergence is reached. Two test feeders composed of 21 and 33 buses are employed for all the numerical validations. The effectiveness of the proposed recursive convex model is verified through the implementation of different metaheuristic algorithms. All the simulations are carried out in the MATLAB programming environment using the convex disciplined tool known as CVX with the SEDUMI and SDPT3 solvers.

关键词： recursive optimal power flow solution sequential quadratic programming bipolar DC networks unbalanced loads power loss minimization

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Solar sail hybrid trajectory optimization for non-Keplerian orbit transfers

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JOURNAL OF GUIDANCE CONTROL AND DYNAMICS 2002年第3期25卷 602-604页

作者： Hughes, GW McInnes, CR Univ Glasgow Dept Aerosp Engn Glasgow G12 8QQ Lanark Scotland

A trajectory optimization tool was developed which hybridized a genetic algorithm (GA) with sequential quadratic programming (SQP). When applied to the difficult problem of preliminary mission planning for high-performance solar sail transfers to displaced non-Keplerian orbits (NKOs), it appeared to identify near-optimal trajectories with relative ease. A small number of segments reduced the computational burden imposed by using a GA.

关键词： Trajectory Optimization Solar Sail Non Keplerian Orbit Earth sequential quadratic programming Ecliptic Earth Centered Inertial Propellant Feedback Control System Nonlinear programming

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