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GENERALIZED COVARIANCE ANALYSIS FOR PARTIALLY AUTONOMOUS DEEP SPACE MISSIONS

JOURNAL OF GUIDANCE CONTROL AND DYNAMICS 1991年第5期14卷 964-972页

作者： BOONE, JN MARTIN MARIETTA CORP DEPT SPACECRAFT ANAL DENVER CO 80201 USA

A new covariance analysis method is presented that is suitable for the evaluation of multiple impulsive controllers acting on some stochastic process x. The method accommodates batch and sequential estimators with equal ease and accounts for time-delay effects in a natural manner. The formalism is developed in terms of a generalized state vector that is formed from the system state vector x, augmented by various fixed epoch estimates, and a data vector formed from discrete time observations of the system. Recursions are developed for time transition, measurement incorporation, and impulsive control updating of the generalized covariance matrix. Means of limiting the dimensional growth of the generalized state vector via the processes of estimator epoch adjustment and measurement vector deflation are described and the application of numerically stable matrix factorization methods to the generalized covariance recursions is outlined. The method is applied to the Magellan spacecraft to demonstrate the capability of ground-based optimal estimation and control of gyro/star scanner misalignment.

关键词： Autonomous Deep Space Missions Kalman Filter Synthetic Aperture Radar Neptune Singular Value Decomposition Orbital Period Data Transmission Computing selection algorithm Spacecraft Attitude

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Sea breeze characteristics on two sides of a shallow gulf: study of the Gulf St Vincent in South Australia

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METEOROLOGICAL APPLICATIONS 2016年第2期23卷 222-229页

作者： Masouleh, Zahra Pazandeh Walker, David John Crowther, John McCauley Univ Adelaide Sch Civil Environm & Min Engn N Terrace Adelaide SA 5005 Australia

A study of the long-term behaviour (1957-2007) of sea breeze characteristics in the coastal city of Adelaide, Australia has been undertaken, applying a sea breeze day selection algorithm that employed four quantitative filters based on the temperature of the sea and land surfaces and the behaviour of surface- and upper-level winds. Despite the similarity of the daily surface wind circulation on non-sea breeze days on both sides of Gulf St Vincent, the westerly wind component of selected sea breeze days for Adelaide has been accompanied by an easterly wind direction on the opposite side of the Gulf, as would be expected. In the last three decades of the study period, where a higher frequency of data was available, the sea breeze has been shown to start at least 4 h after sunrise and normally cease before sunset and thus was of longer duration in summer than in the other seasons. It also appears that the maximum sea breeze intensity in summer months has a comparatively stronger southerly component than in other seasons.

关键词： sea breeze selection algorithm Adelaide

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Calibration and uncertainty analysis for computer simulations with multivariate output

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AIAA JOURNAL 2008年第5期46卷 1253-1265页

作者： McFarland, John Mahadevan, Sankaran Romero, Vicente Swiler, Laura Vanderbilt Univ Dept Mech Engn Nashville TN 37235 USA Vanderbilt Univ Dept Civil & Environm Engn & Mech Engn Nashville TN 37235 USA Sandia Natl Labs Model Validat & Uncertainty Quantificat Dept Albuquerque NM 87185 USA Sandia Natl Labs Optimizat & Uncertainty Estimat Dept Albuquerque NM 87185 USA

Model calibration analysis is concerned with the estimation of unobservable modeling parameters using observations of system response. When the model being calibrated is an expensive computer simulation, special techniques such as surrogate modeling and Bayesian inference are often fruitful. In this paper, we show how the flexibility of the Bayesian calibration approach can be exploited to account for a wide variety of uncertainty sources in the calibration process. We propose a straightforward approach for simultaneously handling Gaussian and non-Gaussian errors, as well as a framework for studying the effects of prescribed uncertainty distributions for model inputs that are not treated as calibration parameters. Further, we discuss how Gaussian process surrogate models can be used effectively when simulator response may be a function of time and/or space (multivariate output). The proposed methods are illustrated through the calibration of a simulation of thermally decomposing foam.

关键词： Probability Distribution Functions Thermocouples Numerical Integration Finite Element Modeling Sandia National Laboratories selection algorithm Bayesian Approach Greedy algorithm Heat Transfer Modeling Maximum Likelihood Estimation

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MINIMUM-TIME REORIENTATION OF A 2-DEGREE-OF-FREEDOM GYROSCOPE

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JOURNAL OF GUIDANCE CONTROL AND DYNAMICS 1995年第4期18卷 782-791页

作者： BOYARSKI, S BENASHER, JZ Tel-Aviv University Ramat Aviv 69978 Israel

The problem of time-optimal reorientation of the inner gimbal of a two-degree-of-freedom gimballed gyroscope mounted on a nonrotating base is considered. The states in the gyro model are the gimbals' angles (nutation is ignored). The model is nonlinear (not limited to small angles), state constrained, control limited, and double input, double output. A simple, explicit solution based on an intuitive observation is presented;it exploits the system's nonlinearity and channel coupling for attaining the minimum-time goal,It is analytically shown, in detail, that the solution satisfies the Maximum Principle and fulfills a sufficient condition for optimality based on the Hamilton-Jacobi-Bellman equation.

关键词： Gyroscopes Degrees of Freedom Hamilton Jacobi Bellman Equation Closed Loop Control Moment Gyroscope Computing Actuator Torque Flexible Spacecrafts selection algorithm Real Time Software

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Microgenetic multiobjective reconfiguration algorithm considering power losses and reliability indices for medium voltage distribution network

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IET GENERATION TRANSMISSION & DISTRIBUTION 2009年第9期3卷 825-840页

作者： Mendoza, J. E. Lopez, M. E. Coello Coello, C. A. Lopez, E. A. Pontificia Univ Catolica Valparaiso Escuela Ingn Elect Valparaiso Chile Ecole Super Elect Dept Energy Gif Sur Yvette France IPN CINVESTAV Dept Comp Sci Mexico City 07738 DF Mexico Univ Concepcion Dept Elect Engn Concepcion Chile

This study proposes and applies an evolutionary-based approach for multiobjective reconfiguration in electrical power distribution networks. In this model, two types of indicators of power quality are minimised: (i) power system's losses and (ii) reliability indices. Four types of reliability indices are considered. A microgenetic algorithm (mGA) is used to handle the reconfiguration problem as a multiobjective optimisation problem with competing and non-commensurable objectives. In this context, experiments have been conducted on two standard test systems and a real network. Such problems characterise typical distribution systems taking into consideration several factors associated with the practical operation of medium voltage electrical power networks. The results show the ability of the proposed approach to generate well-distributed Pareto optimal solutions to the multiobjective reconfiguration problem. In the systems adopted for assessment purposes, our proposed approach was able to find the entire Pareto front. Furthermore, better performance indexes were found in comparison to the Pareto envelope-based selection algorithm 2 (PESA 2) technique, which is another well-known multiobjective evolutionary algorithm available in the specialised literature. From a practical point of view, the results established, in general, that a compact trade-off region exists between the power losses and the reliability indices. This means that the proposed approach can recommend to the decision maker a small set of possible solutions in order to select from them the most suitable radial topology.

关键词： Medium pressures reliability index power loss Power grids voltage distribution selection algorithm Reconfiguration

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Fault-Tolerant Procedures for Redundant Computer Systems

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QUALITY AND RELIABILITY ENGINEERING INTERNATIONAL 2009年第1期25卷 41-68页

作者： Samet, Refik Ankara Univ Dept Comp Engn TR-06100 Ankara Turkey

Real-time computer systems deployed in life-critical control applications must be designed to meet stringent reliability specfications. The minimum acceptable degree of reliability for systems of this type is '7 nines', which is not generally achieved. This paper aims at contributing to the achievement of that degree of reliability. To this end, this paper proposes a classification scheme of the fault-tolerant procedures for redundant computer systems (RCSs). The proposed classification scheme is developed oil the basis of the number of counteracted fault types. Table I is created to relate the characteristics of the RCSs to the characteristics of the fault-tolerant procedures. A selection algorithm is proposed, which allows designers to select the optimal type of fault-tolerant procedures according to the system characteristics and capabilities. The fault-tolerant procedure, which is selected by this algorithm, provides the required degree of reliability for a given RCS. According to the proposed graphical model only a part of the fault-tolerant procedure is executed depending oil the absence or presence (type and sort) of faults. The proposed methods allow designers to counteract Byzantine and non-Byzantine fault types during degradation of RCSs from N to 3, and only the non-Byzantine fault type during degradation from 3 to 1 with optimal checkpoint time period. Copyright (C) 2008 John Wiley & Sons, Ltd.

关键词： redundant computer system fault-tolerant procedure non-Byzantine and Byzantine fault types classifications selection algorithm graphical model

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Performance analysis of zero-forcing-based multiple-input multiple-output two-way relaying in overlay device-to-device communications

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IET COMMUNICATIONS 2016年第6期10卷 699-708页

作者： Gurjar, Devendra Singh Upadhyay, Prabhat Kumar Indian Inst Technol Indore Discipline Elect Engn Indore 452020 Madhya Pradesh India

In this study, the authors conduct the performance evaluation and resource allocation for two-way multiple-input multiple-output-based device-to-device (D2D) communications overlaying a cellular network. The considered system model comprises of a base station, a mobile user, and a pair of D2D users, where each of them is equipped with multiple antennas and employs transmit/receive zero forcing. Based on overlaying approach, both D2D and cellular communications take place bidirectionally by employing analogue network coding with a best selected D2D user as two-way relay for the cellular links. The authors analyse the outage performance of cellular and D2D systems in a Rayleigh fading environment. They also deduce asymptotic outage behaviour of cellular system and highlight the achievable diversity order. In addition, they derive the expressions of ergodic sum rate for both the systems. Above all, they provide a selection algorithm for the best relaying D2D user and describe feasible range of power splitting factor to maximise the data rate of cellular system for a given data rate of D2D system. Numerical and simulation results validate the authors' theoretical findings and illustrate the performance gains of the considered scheme under various antenna configurations.

关键词： Communication Research Device-to-device communication Bidirectional Writers Cells ANTENNA CONFIGURATIONS multiple antenna Cellular communications multiple input multiple output systems cellular system Overlay relaying Performance Evaluation selection algorithm Data transfer rates

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Optimal Approximations of Coupling in Multidisciplinary Models

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AIAA JOURNAL 2018年第6期56卷 2412-2428页

作者： Baptista, Ricardo Marzouk, Youssef Willcox, Karen Peherstorfer, Benjamin MIT Ctr Computat Engn 77 Massachusetts Ave Cambridge MA 02139 USA MIT Dept Aeronaut & Astronaut Cambridge MA 02139 USA Univ Wisconsin Dept Mech Engn Madison WI 53706 USA

This paper presents a methodology for identifying important discipline couplings in multicomponent engineering systems. Coupling among disciplines contributes significantly to the computational cost of analyzing a system and can become particularly burdensome when coupled analyses are embedded within a design or optimization loop. In many cases, disciplines may be weakly coupled, so that some of the coupling or interaction terms can be neglected without significantly impacting the accuracy of the system output. Typical practice derives such approximations in an ad hoc manner using expert opinion and domain experience. This work proposes a new approach that formulates an optimization problem to find a model that optimally balances accuracy of the model outputs with the sparsity of the discipline couplings. An adaptive sequential Monte Carlo sampling-based technique is used to efficiently search the combinatorial model space of different discipline couplings. An algorithm for selecting an optimal model is presented and illustrated in a fire-detection satellite model and a turbine engine cycle analysis model.

关键词： Satellites Attitude Control System High Pressure Turbine Thrust Specific Fuel Consumption Feedforward selection algorithm Eclipses Feedback Loop Number of Particles Numerical Stability

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Selecting profitable custom instructions for reconfigurable processors

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JOURNAL OF SYSTEMS ARCHITECTURE 2010年第8期56卷 340-351页

作者： Tao Li Wu Jigang Lam, Siew-Kei Srikanthan, Thambipillai Lu, Xicheng Natl Univ Def Technol Sch Comp Hunan 410073 Peoples R China Tianjin Polytech Univ Sch Comp Sci & Software Tianjin 300160 Peoples R China Nanyang Technol Univ Sch Comp Engn Singapore 639798 Singapore

Custom-instruction selection is an essential phase in instruction set extension for reconfigurable processors. It determines the most profitable custom-instruction candidates for implementing in the reconfigurable fabric of a reconfigurable processor. In this paper, a practical computing model is proposed for the custom-instruction selection problem that takes into account the area constraint of the reconfigurable fabric. Based on the new computing model, two heuristic algorithms and an exact algorithm are proposed. The first heuristic algorithm, denoted as HEA, dynamically assigns priorities to the custom instruction candidates and incorporates efficient strategies to select custom instructions with the highest priority. The second heuristic algorithm, denoted as TSA, employs an efficient tabu search algorithm to refine the results of HEA to near-optimal ones. Also, a branch-and-bound algorithm (BnB) is proposed to produce exact solutions for relatively small-sized problems or problems with stringent area-constraints. Experimental results show that HEA can produce more specific approximate solutions with a difference of only about 3% when compared to the optimal solutions produced by BnB. This difference is further reduced to about 0.6% by TSA. In addition, for large-sized problems where the exact algorithm becomes prohibitive, HEA and TSA can still produce solutions within reasonable time. (C) 2010 Elsevier B.V. All rights reserved.

关键词： Custom instruction selection algorithm Reconfigurable processors Heuristic Branch-and-bound

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FLIGHT CONTROL-SYSTEM MODE TRANSITIONS INFLUENCE ON HANDLING QUALITIES AND TASK-PERFORMANCE

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JOURNAL OF AIRCRAFT 1994年第5期31卷 1037-1042页

作者： REID, LD RAJAGOPAL, P GRAF, WO University of Toronto Toronto Ontario M3H 5T6 Canada

The Flight Research Simulator of the University of Toronto Institute for Aerospace Studies was modified to represent a fly-by-wire helicopter with a digital flight control system (FCS) and a side-arm controller. Three FCS modes were employed (in addition to the basic airframe version of the helicopter): rate command/attitude hold, attitude command/attitude hold, and translation rate command. A smooth FCS mode selection algorithm was developed and successfully tested. Three types of mode transition were evaluated: 1) transition selected manually by the pilot, 2) transition selected by the FCS accompanied by an audio warning, and 3) transition initiated without warning by a system failure. The pilot/helicopter response to mode transitions was studied for formation flying and precision hover. Both normal- and failure-induced transitions were investigated by a group of 9 evaluation pilots. The results were obtained in the form of Cooper-Harper handling qualities ratings (HQR) and stationkeeping performance measurements. It was found that for the present mode selection algorithm, the type of mode transition from the initial FCS mode to the final FCS mode (i.e., within a mode pair) did not significantly influence the experimental results. However, the mode pair itself was found to influence both HQRs and performance. The mode pairs producing most of the significant effects on HQR and performance contained as one of their elements, the FCS mode having the poorest handling qualities. For mode pairs producing significant effects, it was found in some instances that the mode in place before transition actually influenced the HQRs and performance after transition.

关键词： Handling Qualities Digital Flight Control System Test Pilots Helicopters Flying Wires selection algorithm Airframes Formation Flying Flight Testing Analysis of Variance

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