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General approach to enhance flying qualities via dynamic balancing of aircraft mass

JOURNAL OF AIRCRAFT 2008年第1期45卷 130-141页

作者： Malaek, S. M. Karimi, A. Sharif Univ Technol Dept Aerosp Engn Tehran Iran

This work describes a new mathematical model to predict the so-called aircraft handling qualities via proper positioning of aircraft mass in the early stages of the design process. The methodology aims to help make handling qualities and therefore pilot rating an integral part of the design process. The main idea is to find proper mass distributions for an aircraft in given flight conditions based on the well-known quantitative measures of flying qualities described in military standards. The proposed methodology allows aircraft designers to associate a density to different segments of an aircraft and have a prior insight about an optimum arrangement of internal parts such as fuel tanks,payload containers, passenger seats, and other massy items. Moreover, a new global optimization algorithm based on the Nelder-Mead Simplex method is devised to effectively solve the resulting optimization problem. This work shows how a B-747-100 could be mass balanced to achieve level-I flying qualities for both cruising and turning flights without using any stability augmentation system. Furthermore, the idea of a minimum effort generic control system is introduced that helps reduce the cost of aircraft certification.

关键词： Aircraft Flying Qualities Aeroplane optimization algorithm Nelder Mead Simplex Pilot SAS Control Systems Mathematical Models State Space Representation Aircraft Dynamics

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Deflection-limiting commands for systems with velocity limits

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JOURNAL OF GUIDANCE CONTROL AND DYNAMICS 2008年第3期31卷 472-478页

作者： Sung, Yoon-Gyung Singhose, William E. Chosun Univ Dept Mech Engn Kwangju 501759 South Korea Georgia Inst Technol George W Woodruff Sch Mech Engn Atlanta GA 30332 USA

A new method to generate deflection-limiting commands for systems with velocity limits is presented and evaluated. In addition to limiting transient deflection, the command profiles reduce residual vibration for rest-to-rest motion of oscillatory systems with one dominant mode. A beneficial advantage of the command profiles is that they are described by closed-form functions of the system frequency, deflection-limiting ratio, velocity limit, actuator force-to-mass ratio, and desired move distance. The performance of the commands is evaluated with respect to move duration, transient oscillation energy, maximum transient deflection, and robustness to modeling errors. The proposed approach is illustrated with a numerical simulation of a benchmark system and experimentally validated on a bridge crane.

关键词： Actuators Numerical Simulation Numerical optimization Rigid Body Dynamics Vibrational Energy Fuel Consumption Wireless Local Area Network Inverters optimization algorithm Industrial Applications

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Explicit model predictive control for large-scale systems via model reduction

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JOURNAL OF GUIDANCE CONTROL AND DYNAMICS 2008年第4期31卷 918-926页

作者： Hovland, Svein Gravdahl, Jan Tommy Willcox, Karen E. Norwegian Univ Sci & Technol Dept Engn Cybernet N-7491 Trondheim Norway MIT Dept Aeronaut & Astronaut Cambridge MA 02139 USA

In this paper, we present a framework for achieving constrained optimal real-time control for large-scale systems with fast dynamics. The methodology uses the explicit solution of the model predictive control problem combined with model reduction, in an output-feedback implementation. The explicit solution of the model predictive control problem leads to online model predictive control functionality without having to solve an optimization problem at each time step. Reduced-order models are derived using a goal-oriented, model-constrained optimization formulation that yields efficient models tailored to the control application at hand. The approach is illustrated on a challenging large-scale flow problem that aims to control the shock position in a supersonic diffuser.

关键词： Distributed Parameter System Feedback Control Supersonic Diffusers CFD Analysis Mach Number Algebraic Riccati Equation Kalman Filter optimization algorithm Gaussian White Noise Flow Conditions

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Unsteady discrete adjoint formulation for two-dimensional flow problems with deforming meshes

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AIAA JOURNAL 2008年第6期46卷 1351-1364页

作者： Mani, Karthik Mavriplis, Dimitri J. Univ Wyoming Dept Mech Engn Laramie WY 82071 USA

A method to apply the discrete adjoint for computing sensitivity derivatives in two-dimensional unsteady flow problems is presented. The approach is to first develop a forward or tangent linearization of the nonlinear flow problem in which each individual component building up the complete flow solution is differentiated against the design variables using the chain rule. The reverse or adjoint linearization is then constructed by transposing and reversing the order of multiplication of the forward problem. The developed algorithm is very general in that it applies directly to the arbitrary Lagrangian-Eulerian form of the governing equations and includes the effect of deforming meshes in unsteady flows. It is shown that an unsteady adjoint formulation is essentially a single backward integration in time and that the cost of constructing the final sensitivity vector is close to that of solving the unsteady flow problem integrated forward in time. It is also shown that the unsteady adjoint formulation can be applied to time-integration schemes of different orders of accuracy with minimal changes to the base formulation. The developed technique is then applied to three optimization examples, the first in which the shape of a pitching airfoil is morphed to match a target time-dependent load profile, the second in which the shape is optimized to match a target time-dependent pressure profile, and the last in which the time-dependent drag profile is minimized without any loss in lift.

关键词： Two Dimensional Flow Arbitrary Lagrangian Eulerian Symmetric Airfoil Edge Computing Freestream Mach Number Angle of Attack Euler Equations Roe Approximate Riemann Solver optimization algorithm Computational Fluid Dynamics

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Coordinated standoff tracking of moving targets using Lyapunov guidance vector fields

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JOURNAL OF GUIDANCE CONTROL AND DYNAMICS 2008年第2期31卷 290-306页

作者： Frew, Eric W. Lawrence, Dale A. Morris, Steve Univ Colorado Boulder CO 80302 USA MLB Co Mountain View CA 94043 USA

This paper presents a control structure for cooperative stand-off line-of-sight tracking of a moving target by a team of unmanned aircraft based on a Lyapunov guidance vector field that produces stable convergence to a circling limit cycle behavior. A guidance vector field is designed for a stationary target and then modified with a correction term that accounts for a moving target and constant background wind. Cooperative tracking by multiple unmanned aircraft is achieved through additional phasing, also with a Lyapunov stability analysis. Convoy protection, in which the unmanned aircraft must scout an area ahead of the moving target, is performed by extending the cooperative stand-off line-of-sight limit cycle attractor along the direction of travel. Simulation results demonstrate the behavior of the algorithms as well as the improvement that results from cooperation. Finally, simulations of a larger cooperative search, acquisition, and tracking scenario are described that illustrate the use of the cooperative standoff line-of-sight and convoy protection controllers in a realistic application.

关键词： Lyapunov Stability Theory Standoff Tracking Flight Control System Aircraft Speed Track algorithm optimization algorithm Heading Angle Guidance Laws GPS Control algorithm

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Effectiveness of complex design through an evolutionary approach

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JOURNAL OF THERMOPHYSICS AND HEAT TRANSFER 2008年第1期22卷 115-118页

作者： Pedro, H. Kobayashi, M. H. Coimbra, C. F. M. da Silva, A. K. Univ Hawaii Dept Mech Engn Honolulu HI 96822 USA Univ Calif Sch Engn Merced CA 95344 USA

The effectiveness and the robustness of added complexity of a family of trees through the use of an evolutionary optimization algorithm is presented. The method is use to illustrate the solution process for an area-to-point-type heat transfer problem. The optimization of the dendritic structure is performed using a script developed for the genetic algorithm toolbox from MATLAB. This is suitable for an evolutionary optimization of multi-independent variables problems. Parental selection is based on the stochastic uniform method, which means that the contribution of each parent is proportional to the value of its fitness function. Genetic algorithm evolutionary process presents that the complexity level can be an important parameter in design.

关键词： Conduction Heat Transfer Entropy Generation Finite Element Method Numerical Simulation Genetic algorithm Four Degree of Freedom Laws of Thermodynamics optimization algorithm Topology optimization Reversible Process

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A New Model-Based algorithm for Optimizing the MPEG-AAC in MS-Stereo

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IEEE TRANSACTIONS ON AUDIO SPEECH AND LANGUAGE PROCESSING 2008年第8期16卷 1373-1382页

作者： Derrien, Olivier Richard, Gael Univ Sud Toulon Var ISITV F-83957 La Garde France CNRS LTCI Inst TELECOM F-75014 Paris France

In this paper, a new model-based algorithm for optimizing the MPEG-Advanced Audio Coder (AAC) in MS-stereo mode is presented. This algorithm is an extension to stereo signals of prior work on a statistical model of quantization noise. Traditionally, MS-stereo coding approaches replace the Left (L) and Right (R) channels by the Middle (M) and Sides (S) channels, each channel being independently processed, almost like a monophonic signal. In contrast, our method proposes a global approach for coding both channels in the same process. A model for the quantization error allows us to tune the quantizers on channels M and S with respect to a distortion constraint on the reconstructed,channels L and R as they will appear in the decoder. This approach leads to a more efficient perceptual noise-shaping and avoids using complex psychoacoustic models built on the M and S channels. Furthermore, it provides a straightforward scheme to choose between LR and MS modes in each subband for each frame. Subjective listening tests prove that the coding efficiency at a medium bitrate (96 kbits/s for both channels) is significantly better with our algorithm than with the standard algorithm, without increase of complexity.

关键词： Bitrate constraint distortion constraint MPEG-Advanced Audio Coder (AAC) MS-stereo optimization algorithm perceptual audio coding scalefactor statistical model quantization

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Modeling and parameter identification of microbial bioconversion in fed-batch cultures

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JOURNAL OF PROCESS CONTROL 2008年第5期18卷 458-464页

作者： Wang, Gang Feng, Enmin Xiu, Zhilong Dalian Univ Technol Dept Appl Math Dalian 116024 Liaoning Peoples R China Dalian Univ Technol Dept Biotechnol Dalian 116024 Liaoning Peoples R China

In this study, the nonlinear dynamical system of glycerol bio-dissimilation to 1,3-propanediol by Klebsiella pneumoniae in fed-batch cultures is investigated. Because of the abrupt changes of reactant concentrations in fed-batch cultures, the continuous dynamical system previously used is inappropriate to describe the process of fed-batch cultures. In this respect we present a nonlinear impulsive dynamical system of glycerol bioconversion to.1,3-propanediol in fed-batch cultures based on the dynamical system of batch cultures. Then we study some properties of the piecewise continuous solutions to the proposed impulsive system. More important, observing the bigger errors between the experimental results and computational ones obtained from the initial parameters of the dynamical system of batch cultures which was derived from hundreds of practical chemical experiments, we establish a parameter identification model for the impulsive system. Subsequently the existence of the optimal solutions of model is demonstrated by using the compactness of the set of the system solutions and an optimization algorithm is constructed to seek to the optimal parameters of the proposed system by means of the genetic optimization. Finally an illustrative numerical example shows the appropriateness of the nonlinear impulsive system and the validity of optimization algorithm. (c) 2007 Elsevier Ltd. All rights reserved.

关键词： fed-batch bioconversion nonlinear impulsive system parameter identification optimization algorithm

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Modified PSO algorithm for solving planar graph coloring problem

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自然科学进展（英文版） 2008年第3期18卷 353-357页

作者： Guangzhao Cui Limin Qin Sha Liu Yanfeng Wang Xuncai Zhang Xianghong Cao College of Electrical and Electronic Engineering Zhengzhou University of Light IndustryZhengzhou 450002China Research Institute of Biomolecular Computer Huazhong University of Science and TechnologyWuhan 430074China

The graph coloring is a classic NP-complete problem. Presently there is no effective method to solve this problem. Here we propose a modified particle swarm optimization (PSO) algorithm in which a disturbance factor is added to a particle swarm optimizer for improving its performance. When the current global best solution cannot be updated in a certain time period that is longer than the disturbance factor, a certain number of particles will be chosen according to probability and their velocities will be reset to force the particle swarm to get rid of local minimizers. It is found that this operation is helpful to improve the performance of particle swarm. Classic planar graph coloring problem is resolved by using modified particle swarm optimization algorithm. Numerical simulation results show that the per-formance'of the modified PSO is superior to that of the classical PSO.

关键词： Planar graph coloring problem PSO optimization algorithm

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Providing fault tolerance in wireless backhaul network design with path restoration

Providing fault tolerance in wireless backhaul network desig...

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3rd International Conference on Availability, Reliability and Security

作者： Leesutthipornchai, Pakorn Wattanapongsakorn, Naruemon Charnsripinyo, Chalermpol Natl Elect & Comp Technol Ctr Pathum Thani Thailand King Mongkuts Univ Technol Dept Comp Engn Bangkok 10140 Thailand

ISBN: (纸本)9780769531021

This paper presents a survivable network design using network path restoration approach to provide fault tolerance in cellular backhaul network design, so that any breakdown of links within a network path can no longer interrupt the network services. As a consequence, the network design can greatly enhance the network reliability and quality of services. We adopt a two-phase network design approach to reduce the complexity of network design and to provide a design mechanism for enhancing reliability in existing networks. The first phase provides a minimum-cost initial network design. The problem is to find a minimum-cost network topology which includes selecting the location and type of base station controllers and mobile switching controllers as well as their link types. The second phase provides backup paths and spare capacity to the network topology from phase one to improve network reliability. Due to the complexity of network design problem, a genetic algorithm is applied as a meta-heuristic technique for obtaining good solutions. Various problem sizes of example networks are considered and discussed,

关键词： survivable network design network path restoration optimization algorithm genetic algorithm

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