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On the Convex Parameterization of Constrained Spacecraft Reorientation

IEEE TRANSACTIONS ON AEROSPACE AND ELECTRONIC SYSTEMS 2010年第3期46卷 1097-1109页

作者： Kim, Yoonsoo Mesbahi, Mehran Singh, Gurkirpal Hadaegh, Fred Y. Univ Stellenbosch Dept Mech & Mech Engn ZA-7600 Stellenbosch South Africa Univ Washington Dept Aeronaut & Astronaut Seattle WA 98195 USA CALTECH Jet Prop Lab Pasadena CA 91109 USA

Guiding the rotational motion of a spacecraft subject to constraints on its permissible orientation often leads to nonconvex optimal control problems. In this paper, we consider convex parameterizations of sets associated with the constrained rigid body orientations. We then elaborate on ramifications of such a parameterization in the development of steering laws for autonomous spacecraft reorientation that are based on convex optimization algorithms. Such problems appear in almost every space science mission equipped with heat- or light-sensitive instruments, e. g., cryogenically cooled infrared telescopes, star trackers, and low-energy ion composition analyzers. An example, demonstrating the viability of the proposed algorithm for constrained multiple spacecraft reorientations concludes the work presented here.

关键词： Vocational Rehabilitation Optimal control Convexity Spacecraft Viability optimization algorithms AEROSPACE SCIENCES SETTING parameterization ROTATIONAL MOTION

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Linking GIS, Hydraulic Modeling, and Tabu Search for Optimizing a Water Level-Monitoring Network in South Florida

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JOURNAL OF WATER RESOURCES PLANNING AND MANAGEMENT 2010年第2期136卷 167-176页

作者： Martinez, Sergio I. Merwade, Venkatesh Maidment, David Purdue Univ Sch Civil Engn W Lafayette IN 47907 USA Univ Autonoma Aguascalientes Aguascalientes 20100 Ags Mexico Univ Texas Austin Ctr Res Water Resources Austin TX 78758 USA

The South Florida Water Management District (SFWMD) has a large and expanding surface water level-monitoring network for various water bodies including lakes and streams. SFWMD seeks to optimize the existing network of monitoring stations to collect the data from the least number of monitoring stations in the best possible locations without compromising information. Tabu combinatorial search algorithm is used to optimize water level-monitoring stations in lakes and streams within the SFWMD. Given a network of n stations, the methodology involves searching for the best spatial combination of r (where r < n) monitoring stations within the existing network to estimate water surface levels in lakes and streams within a given tolerance. Separate techniques are used to compute water levels in lakes and streams to compare possible solutions from Tabu search with observed daily data. Results from application of proposed techniques to Kissimmee River basin show that implementation of Tabu search within geographic information system (GIS) provides a computationally efficient way of optimizing a water level-monitoring network. It is also found that factors such as length of data records, slope of hydraulic profiles, and data at control structures play a significant role in the overall optimization process. The proposed methodology can also be used in the design of new monitoring networks and other water resources applications that involve GIS, computational modeling, and optimization.

关键词： Water levels Water surface profiles Monitoring network Hydraulic models optimization algorithms Combinatorial search

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Optimisation of multi-frequency microstrip antenna using genetic algorithm coupled with method of moments

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IET MICROWAVES ANTENNAS & PROPAGATION 2010年第4期4卷 477-483页

作者： Sathi, V. Taherizadeh, S. Lotfi, A. Ghobadi, C. AREC Tabriz Iran Tarbiat Modares Univ Dept Informat Technol IT Engn Tehran Iran RAZI Univ Dept Elect Engn Kermanshah Iran Urmia Univ Dept Elect Engn Orumiyeh Iran

Derivation of the closed form Green's functions and analytical evaluation of the method of moments (MOM) matrix entries have improved the computational efficiency significantly in the analysis of printed geometries. With this background in mind, an extension of this efficient numerical technique is to incorporate an optimisation algorithm and to assess its potential as a computer-aided design (CAD) tool. Therefore the authors have employed the genetic algorithms (GAs) in conjunction with the electromagnetic (EM) simulation technique, to a number of representative examples. Simulation and experimental results are in good agreement with GA optimisation results. Proposed optimisation method can be safely used in microwave CAD applications.

关键词： Genetic Algorithm (GA) multiple-frequency evaluation method optimization algorithms Microstrip antennas METHOD OF MOMENTS Computational efficiency Numerical methods Computer-Aided Design DFFB gene derivation

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A two-player competitive discrete location model with simultaneous decisions

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EUROPEAN JOURNAL OF OPERATIONAL RESEARCH 2010年第3期207卷 1419-1432页

作者： Godinho, Pedro Dias, Joana Univ Coimbra Fac Econ P-3004512 Coimbra Portugal Univ Coimbra Inesc Coimbra P-3004512 Coimbra Portugal Univ Coimbra GEMF P-3004512 Coimbra Portugal

In this paper we will describe and study a competitive discrete location problem in which two decision-makers (players) will have to decide where to locate their own facilities, and customers will be assigned to the closest open facilities. We will consider the situation in which the players must decide simultaneously, unsure about the decisions of one another, and we will present the problem in a franchising environment. Most problems described in the literature consider sequential rather than simultaneous decisions. In a competitive environment, most problems consider that there is a set of known and already located facilities, and new facilities will have to be located, competing with the existing ones. In the presence of more than one decision-maker, most problems found in the literature belong to the class of Stackelberg location problems, where one dKision-maker, the leader, locates first and then the other decision-maker, the follower, locates second, knowing the decisions made by the first. These types of problems are sequential and differ significantly from the problem tackled in this paper, where we explicitly consider simultaneous, non-cooperative discrete location decisions. We describe the problem and its context, propose some mathematical formulations and present an algorithmic approach that was developed to find Nash equilibria. Some computational tests were performed that allowed us to better understand some of the features of the problem and the associated Nash equilibria. Among other results, we conclude that worsening the situation of player tends to benefit the other player, and that the inefficiency of Nash equilibria tends to increase with the level of competition. (C) 2010 Elsevier B.V. All rights reserved.

关键词： Location Game theory Simultaneous decisions optimization algorithms Nash equilibrium

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Application of the election campaign optimization algorithm to engineering optimum design problems

Application of the election campaign optimization algorithm ...

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2010 International Symposium on Computational Intelligence and Design, ISCID 2010

作者： He, Chunhua Zhang, Xiangwei Faculty of Materials and Energy Guangdong University of Technology Guangzhou China Faculty of Electro-Mechanics Engineering Guangdong University of Technology Guangzhou China

ISBN: (纸本)9780769541983

This paper investigates the application of Election Campaign Algorithm (ECA) in the optimum design of engineering problems. With ECA'S characteristic of running side by side, the overall optimization and feasible operation, the optimum matching of the design variables is obtained based on the optimum design model of engineering problems. Simulation results based on well-known constrained engineering design problems demonstrate the reliability and feasibility of ECA's application. ECA is suitable for solving engineering optimization design problems. © 2010 IEEE.

关键词： Election Campaign Algorithm engineering problems optimization Optimal design design variable design problems Engineering campaign life ECONOMIC COMMISSION FOR AFRICA European Court of Auditors optimization algorithms

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Green Scheduling to minimize Base station Transmit power and UE circuit power consumption

Green Scheduling to minimize Base station Transmit power and...

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IEEE International Symposium on Personal, Indoor and Mobile Radio Communications

作者： Rohit Gupta Emilio Calvanese Strinati CEA LETI MINATEC

ISBN: (纸本)9781457713460

Packet scheduling algorithms are viewed as one of the key mechanisms for increasing the diversity order, robustness and effectiveness of a wireless multi-user communication systems. Traditional packet scheduling algorithms are designed to save energy at the Base-station (BS) in downlink by exploiting tradeoffs between spectral efficiency, delay and energy while at the same time meeting the QoS requirements of the system. However, these algorithms ignore the User-Equipment (UE) circuit power consumption to receive and process downlink traffic. In this paper, we show that the optimization of only BS transmit power consumption in downlink can lead to significant drain of UE battery power. Hence, we propose sub-optimal algorithms that exploit Discontinuous Transmission (DTX) at the base-station to tradeoff delay with energy consumption to improve Energy Efficiency (EE) of the UE circuit power and BS transmit power, while at the same time meeting the application QoS requirements in terms of throughput and service delay. The proposed algorithm is also shown to achieve good performance in saving transmit power at the base-station and also the UE circuit power consumption over traditional scheduling algorithms.

关键词： BASE STATION UNITED ELECTRIC Scheduling algorithms Transmitter power Power consumption Energy sources optimization algorithms Downlink Bahamas

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Selection of locations of knots for linear splines in random regression test-day models

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JOURNAL OF ANIMAL BREEDING AND GENETICS 2010年第2期127卷 87-92页

作者： Jamrozik, J. Bohmanova, J. Schaeffer, L. R. Univ Guelph Ctr Genet Improvement Livestock Dept Anim & Poultry Sci Guelph ON N1G 2W1 Canada

P>Using spline functions (segmented polynomials) in regression models requires the knowledge of the location of the knots. Knots are the points at which independent linear segments are connected. Optimal positions of knots for linear splines of different orders were determined in this study for different scenarios, using existing estimates of covariance functions and an optimization algorithm. The traits considered were test-day milk, fat and protein yields, and somatic cell score (SCS) in the first three lactations of Canadian Holsteins. Two ranges of days in milk (from 5 to 305 and from 5 to 365) were taken into account. In addition, four different populations of Holstein cows, from Australia, Canada, Italy and New Zealand, were examined with respect to first lactation (305 days) milk only. The estimates of genetic and permanent environmental covariance functions were based on single- and multiple-trait test-day models, with Legendre polynomials of order 4 as random regressions. A differential evolution algorithm was applied to find the best location of knots for splines of orders 4 to 7 and the criterion for optimization was the goodness-of-fit of the spline covariance function. Results indicated that the optimal position of knots for linear splines differed between genetic and permanent environmental effects, as well as between traits and lactations. Different populations also exhibited different patterns of optimal knot locations. With linear splines, different positions of knots should therefore be used for different effects and traits in random regression test-day models when analysing milk production traits.

关键词： Knots linear splines optimization algorithms random regressions test-day model

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DIFFERENTIAL-GEOMETRIC CHARACTERISTICS OF OPTIMIZED GENERALIZED COORDINATES PARTITIONED VECTORS FOR HOLONOMIC AND NON-HOLONOMIC MULTIBODY SYSTEMS

DIFFERENTIAL-GEOMETRIC CHARACTERISTICS OF OPTIMIZED GENERALI...

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ASME International Design Engineering Technical Conferences/Computers and Information in Engineering Conference

作者： Terze, Zdravko Matijasevic, Dubravko Vrdoljak, Milan Koroman, Vladimir Univ Zagreb Dept Aeronaut Engn F Mech Eng & Naval Arch Zagreb 41000 Croatia

ISBN: (纸本)9780791849019

Differential-geometric characteristics and structure of optimized generalized coordinates partitioned vectors for generally constrained multibody systems are discussed. Generalized coordinates partitioning is well-known procedure that can be applied in the framework of numerical integration of DAE systems. However, although the procedure proves to be a very useful tool, it is known that an optimization algorithm for coordinates partitioning is needed to obtain the best performance. After short presentation of differential-geometric background of optimized coordinates partitioning, the structure of optimally partitioned vectors is discussed on the basis of gradient analysis of separate constraint sub-manifolds at configuration and velocity level when holonomic and non-holonomic constraints are present in the system. While, in the case of holonomic systems, the vectors of optimally partitioned coordinates have the same structure for generalized positions and velocities, when non-holonomic constraints are present in the system, the optimally partitioned coordinates generally differ at configuration and velocity level and separate partitioned procedure has to be applied. The conclusions of the paper are illustrated within the framework of the presented numerical example.

关键词： optimization algorithms Multibody systems

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ROBUST LEFT VENTRICLE SEGMENTATION FROM ULTRASOUND DATA USING DEEP NEURAL NETWORKS AND EFFICIENT SEARCH METHODS

ROBUST LEFT VENTRICLE SEGMENTATION FROM ULTRASOUND DATA USIN...

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7th IEEE International Symposium on Biomedical Imaging: From Nano to Macro

作者： Carneiro, Gustavo Nascimento, Jacinto Freitas, Antonio Inst Super Tecn Inst Sistemas & Robot Av Rovisco Pais P-1049001 Lisbon Portugal Hosp Fernando Fonseca Dept Cardiol Amadora Portugal

ISBN: (纸本)9781424441266

The automatic segmentation of the left ventricle of the heart in ultrasound images has been a core research topic in medical image analysis. Most of the solutions are based on low-level segmentation methods, which uses a prior model of the appearance of the left ventricle, but imaging conditions violating the assumptions present in the prior can damage their performance. Recently, pattern recognition methods have become more robust to imaging conditions by automatically building an appearance model from training images, but they present a few challenges, such as: the need of a large set of training images, robustness to imaging conditions not present in the training data, and complex search process. In this paper we handle the second problem using the recently proposed deep neural network and the third problem with efficient searching algorithms. Quantitative comparisons show that the accuracy of our approach is higher than state-of-the-art methods. The results also show that efficient search strategies reduce ten times the run-time complexity.

关键词： Segmentation of the left ventricle of the heart deep neural networks optimization algorithms

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A ROBUST METHOD TO DETERMINE STATISTICAL PARAMETERS FOR CLEAVAGE FRACTURE EVALUATION

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Pressure Vessels and Piping Conference of the American-Society-of-Mechanical-Engineers

作者： Ko, Han-Ok Choi, Jae-Boong Kim, Young-Jin Sungkyunkwan Univ Suwon Gyeonggi Do South Korea

ISBN: (纸本)9780791843680

During the last couple of decades, several design guidelines and codes relating to major nuclear components have been introduced and revised for risk-based design and evaluation. It is an important process to determine statistical parameters in practice, for instance, by using the traditional method of moments and Maximum Likelihood Method (MLM). Since appropriate estimation of the parameters is not easy due to mathematical complexity, a robust method adopting concepts of both Chi-Square test and genetic algorithm (GA) is proposed in this paper. The Chi-Square test is a useful technique to get the goodness-of-fit of distributions, which is represented in terms of error between observed frequencies and frequencies calculated by assumed probability density function (PDF) of certain statistical distribution. The GA is an efficient optimization algorithm to solve nonlinear optimum problems. Using the Chi-Square test, statistical parameters can be determined and transferred to an optimum problem, and then solved by the GA employing proper nonlinear objective function. Reliability of the proposed method is verified against fracture toughness test data sets of SA508 reactor pressure vessel material obtained from PCVN specimens at various temperatures. The large scatter of experimental data is examined in use of a distribution reported by Neville and Kennedy, Burr type III and XII distributions by Nadarajah and Kortz as well as well-known Weibull distribution. A systematic assessment is carried out by using the new method and its results are compared with corresponding ones derived from the traditional method. Pros and corns of the alternative distributions as well as technical findings from the statistical assessment are fully discussed to show applicability of them.

关键词： Fracture toughness Goodness-of-fit tests Probability Risk-based design Temperature Fracture (Process) Genetic algorithms Method of moments Design Electromagnetic scattering optimization algorithms Reactor vessels Statistical distributions Fracture (Materials) Weibull distribution Density Reliability Errors

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