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APPROXIMATION-BASED GLOBAL optimization STRATEGY FOR STRUCTURAL SYNTHESIS

AIAA JOURNAL 1993年第1期31卷 180-188页

作者： SEPULVEDA, AE SCHMIT, LA University of California Los Angeles Los Angeles California 90024

A global optimization strategy for structural synthesis based on approximation concepts is presented. The methodology involves the solution of a sequence of high-quality approximate problems using a globala* optimization algorithm. The globala* optimization algorithm implemented consists of a branch and bound strategy based on the interval evaluation of the objective function and constraint functions, combined with a local feasible directions algorithm. The approximate design optimization problems are constructed using first-order approximations of selected intermediate response quantities in terms of intermediate design variables. Numerical results for some example problems known to exhibit relative minima are presented to illustrate the efficacy of the design procedure set forth.

关键词： Structural Synthesis Problems optimization algorithm Finite Element Modeling Structural optimization Structural Dynamics Beam (Structures) Trusses Dynamic Displacements Sensitivity Analysis Aerospace Engineering

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IMPROVED COORDINATION IN NONHIERARCHIC SYSTEM optimization

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AIAA JOURNAL 1993年第12期31卷 2367-2373页

作者： RENAUD, JE GABRIELE, GA RENSSELAER POLYTECH INST DEPT MECH ENGN AERONATU ENGN & MECHTROYNY 12180

An improved coordination procedure for the optimization of nonhierarchic systems by decomposition into reduced subspaces is presented. A subspace coordination procedure based on sequential global approximation is extended to include second-order information. This second-order global approximation is formed using information obtained during subspace optimizations. The use of second-order information in the coordination procedure results in improved convergence for nonhierarchic system optimization as compared with the authors' earlier studies using a first-order coordination procedure. The same objective function and cumulative constraints are imposed at each subspace. Nonlocal functions are approximated at the subspaces using global sensitivities. The method optimizes subspace problems concurrently, allowing for parallel processing. Following each sequence of concurrent subspace optimizations, a second-order approximation of the global problem is formed using design data accumulated during the subspace optimizations. The solution of the global approximation problem is used as the starting point for subsequent subspace optimizations in an iterative solution procedure.

关键词： Iterative Solution Taylor Series Multidisciplinary Design optimization algorithm Performance Aeronautical Engineering optimization algorithm Control optimization Structural Dynamics Manufacturing Cost

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DISCRETE-TIME MODEL-REDUCTION IN LIMITED FREQUENCY RANGES

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JOURNAL OF GUIDANCE CONTROL AND DYNAMICS 1993年第6期16卷 1125-1130页

作者： HORTA, LG JUANG, JN LONGMAN, RW NASA Langley Research Center Hampton Virginia 23665

A mathematical formulation for model reduction of discrete-time systems such that the reduced-order model represents the system in a particular frequency range is discussed. The algorithm transforms the full-order system into balanced coordinates using frequency-weighted discrete controllability and observability grammians. In this form a criterion is derived to guide truncation of states based on their contribution to the frequency range of interest. Minimization of the criterion is accomplished without need for numerical optimization. Balancing requires the computation of discrete frequency-weighted grammians. Closed-form solutions for the computation of frequency-weighted grammians are developed. Numerical examples are discussed to demonstrate the algorithm.

关键词： Numerical optimization Frequency Response Functions Spacecraft Dynamics Singular Value Decomposition White Noise optimization algorithm Lyapunov Equation Aerospace Engineering Cost Analysis

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OPTIMAL SELECTION OF WEIGHTING MATRICES IN INTEGRATED DESIGN OF STRUCTURES CONTROLS

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AIAA JOURNAL 1993年第4期31卷 714-720页

作者： SUNAR, M RAO, SS Purdue University West Lafayette Indiana 47907

A methodology is developed for the optimal selection of state and input weighting matrices, Q and R, respectively, of the linear quadratic regulator (LQR) method in the integrated design of structures/controls. An optimal control problem is set up in such a way that design variables are the diagonal entries of Q and R, the objective function is the trace of the solution matrix to the algebraic Riccati equation of the LQR method, P matrix;and constraints are imposed on the closed-loop eigenvalues to satisfy minimum stability conditions for the control system. The procedure finds the optimal diagonal Q and R that enables the actively controlled system to meet the prespecified stability and performance bounds. Furthermore, the resulting Q and R yield the minimum possible performance index and hence the control effort is substantially reduced. The proposed method is integrated with a substructure decomposition scheme which results in substantial savings on the numerical computations with very little loss in the accuracy of the original system response. It is found that for trusslike space structures, the proposed optimization scheme is mostly affected by the changes in the diagonal terms of R and the changes in the velocity diagonal terms of Q of the controlled system. The method is expected to be very useful for large-scale systems and is illustrated with the help of two example problems.

关键词： Linear Quadratic Regulator Trusses Flexible Structures Structural Modeling Algebraic Riccati Equation Multivariable Control Stiffness Matrices Vibration Suppression Young's Modulus optimization algorithm

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OPTIMAL RECOVERY FROM MICROBURST WIND SHEAR

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JOURNAL OF GUIDANCE CONTROL AND DYNAMICS 1993年第6期16卷 1010-1017页

作者： MULGUND, SS STENGEL, RF Princeton University Princeton New Jersey 08544

The flight path of a twin-jet transport aircraft is optimized in a microburst encounter during approach to landing. The objective is to execute an escape maneuver that maintains safe ground clearance, establishes a positive climb rate as soon as possible after the abort is triggered, and maintains an adequate stall margin during the climb out. A cost function penalizing rate of climb deviations from a nominal value and rate of elevator deflection produces qualitatively good results in a variety of microburst encounters. The optimal maneuver is a gradual pitch-up that ceases near the core of the microburst, followed by a slight reduction in pitch attitude in the tailwind area of the microburst. A minimum airspeed constraint in the optimization prevents excessive airspeed loss in very severe microbursts. The aircraft equations of motion include short-period dynamics, so that the optimization produces the control surface deflections required to achieve the optimal flight paths.

关键词： Microburst Rate of Climb Elevator Deflection Elevator Transport Aircraft Trajectory optimization Pilot optimization algorithm Feedback Control Aerodynamic Coefficients

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Toward a Science of Command, Control, and Communications

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丛书名： Progress in Astronautics and Aeronautics

1993年

作者： Carl Jones

ISBN: (数字)9781600866296

ISBN: (纸本)9781563470684

To properly engineer systems to provide unity of effort in command and control systems, it is necessary to have a science of command, control, and communications (C3). This book, the results of the Joint Directors of Laboratories Basic Research Group Program, is a collection of papers toward the goal of a science of C3. The topics include the logic of data fusion, command and control decision systems modeling and behavior, experimental findings, models of command and control, and models of C3 architectures. This variety provides the reader with state-of-the-art perspective on concepts, models, and experiments to understand command, control, and communications. The results of a focused DoD basic research program in command, control and communications will be of particular interest to professionals and students working in the C3 field.

关键词： Aeronautics Air Traffic Control Air Traffic Management algorithms and Data Structures Anti-Submarine Warfare Applied Mathematics Artificial Intelligence Artillery Systems Aviation Aviation Communication Avionics Combat Aircraft Communication System Computational Fluid Dynamics Computer Programming and Language Computing and Informatics Computing, Information, and Communication Control Systems Control Theory Data Analysis Data Analytics Data Management Data Processing Data Science Databases Defense Agencies Evolutionary algorithm Fluid Dynamics General Physics Genetic algorithm Guidance, Navigation, and Control Systems Guided Missiles Information System Kalman Filter Machine Learning Major Command Military Aircraft Military Aviation Military Science Military Technology Missile Defense Missile Guidance and Control Missile Systems, Dynamics and Technology Missiles Navigational Guidance Non-Combat Aircraft Numerical Analysis Operating Systems optimization algorithm RADAR Robotics Sensors Signal Processing Software Systems Statistical Analysis Structural Analysis Structural Engineering Structural Modeling and Simulation Structures, Design and Test Systems Software Tracking and Positioning Systems Transducers United States Air Force United States Armed Forces Warfare and Military Operations Weapon Systems

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INDICIAL LIFT APPROXIMATIONS FOR 2-DIMENSIONAL SUBSONIC FLOW AS OBTAINED FROM OSCILLATORY MEASUREMENTS

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JOURNAL OF AIRCRAFT 1993年第3期30卷 340-351页

作者： LEISHMAN, JG University of Maryland at College Park College Park Maryland 20742

An approach is described to obtain generalized approximations to the indicial lift response due to angle of attack and pitch rate in two-dimensional subsonic flow. Starting from an assumed representation, the approximations are accomplished by means of a nongradienta* optimization algorithm in which the coefficients of the approximation are free parameters. The optimization is subject to prescribed constraints in terms of the known initial and asymptotic behavior of the indicial response, and by requiring the response duplicate the known exact (analytic) solutions at earlier values of time. The approach is applied to extract the intermediate forms of the indicial lift response, generalized in terms of Mach number and pitch axis location, from experimental measurements of the unsteady lift in the frequency domain.

关键词： Incompressible Flow Freestream Mach Number Lift Coefficient Frequency Domain optimization algorithm Cambered Airfoil Wake Vortices Blade Vortex Interaction Compressibility Aeroelastic Analysis

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COMPUTATION OF MAXIMIZED GUST LOADS FOR NONLINEAR AIRCRAFT USING MATCHED-FILTER-BASED SCHEMES

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JOURNAL OF AIRCRAFT 1993年第5期30卷 763-768页

作者： SCOTT, RC POTOTZKY, AS PERRY, B NASA Langley Research Center Hampton Virginia 23681 Lockheed Engineering and Sciences Company Hampton Virginia 23665

This article describes and illustrates two matched-filter-theory-based schemes for obtaining maximized and time-correlated gust loads for a nonlinear airplane. The first scheme is computationally fast because it uses a simple one-dimensional search procedure to obtain its answers. The second scheme is computationally slow because ft uses a more complex multidimensional search procedure to obtain its answers, but it consistently provides slightly higher maximum loads than the first scheme. Both schemes are illustrated with numerical examples involving a nonlinear control system.

关键词： Mach Number Model Aircraft Nonlinear Control Atmospheric Turbulence Nonlinear Systems optimization algorithm Computing Federal Aviation Administration Linear Quadratic Gaussian Aeroservoelasticity

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Introduction to Dynamics and Control of Flexible Structures

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丛书名： AIAA Education Series

1993年

作者： John L. Junkins Youdan Kim

ISBN: (数字)9781600862076

ISBN: (纸本)9781563470547

Effective control laws for mechanical systems are best designed by professionals who understand both the basic mechanics of the system under consideration and the control methodology being used to design the control law. This textbook blends two traditional disciplines: engineering mechanics and control engineering. Beginning with theory, the authors proceed through computation to laboratory experiment and present actual case studies to illustrate practical aerospace applications. Intended for first-year graduate students in engineering and applied science, this book will help structural dynamists and control engineers gain broad competence in mechanics and control. A solutions manual is available for professors.

关键词： Aeronautics algorithms and Data Structures Applied Mathematics Autonomous Systems Avionics Avionics Computers Beam (Structures) Classical Mechanics Computational Fluid Dynamics Computer Networks Computer Programming and Language Computer Storage Devices Computing System Computing and Informatics Computing, Information, and Communication Control Systems Control Theory Data Science Elementary Algebra Embedded Systems Energy Energy Forms Energy Forms, Production and Conversion Feedback Control Finite Element Method Flexible and Active Structures Fluid Dynamics General Physics Geometry Functions Guidance, Navigation, and Control Systems Inverse Problems Kalman Filter Mathematical Analysis Mathematical optimization Mechanical and Structural Vibrations Numerical Analysis Optimal Control Theory optimization algorithm Riccati Equations Robotics Robots Sensors Signal Processing Spacecraft Guidance and Control Structural Analysis Structural Design and Development Structural Engineering Structural Kinematics and Dynamics Structural Modeling and Simulation Structural System Structures, Design and Test Transducers Vibration Control

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GENERALIZED COMPOUND SCALING algorithm AND APPLICATION TO MINIMUM WEIGHT DESIGN OF PLATE STRUCTURES

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AIAA JOURNAL 1992年第10期30卷 2532-2539页

作者： GRANDHI, RV VENUGOPAL, NS VENKAYYA, VB WRIGHT LAB WRIGHT PATTERSON AFB OH 45433 USA

This paper presents the generalized compound scaling algorithm and its application to optimum weight design of plate structures. The optimum designs are reached by simply scaling the design variables to an optimum intersection of multiple constraints. A four-noded isoparametric plate element is used for modeling the structure. Sensitivity computations and thea* optimization algorithm are discussed. The optimization cost involved (excluding the finite element analyses) is very small using this algorithm. The procedure is demonstrated on three example problems using stress and displacement constraints with side bounds on the design variables.

关键词： algorithms and Applications optimization algorithm Finite Element Modeling Transverse Shear Sensitivity Analysis Structural optimization Material Properties Cantilever Beam Nastran Structural Weight

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