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Conference on Optical Design and Engineering

作者： Pizarro, C Arasa, J Tomás, N Tech Univ Catalonia Ctr Dev Sensors Instruments & Syst E-08222 Terrassa Spain

ISBN: (纸本)0819451339

In this work, we present a new image-quality-based optimization process using a USAAF test to estimate the contrast function in the image plane. This strategy permits us to estimate the contrast values with only one image for the analyzed field, so the computation time of the method is appropriated for an optimization process. This image-quality-based procedure does not present the typical problems in estimating the contrast value in optical systems with odd wave-aberrations because the method uses an image of one extended object. The optimization process is applied to design triplet systems. For a triplet lens system working with an f-number of eight, we obtain a design with a Strehl ratio of 0.91 at full field of view using our optimization process. Finally, we present the optimization process' dependence on the starting systems which is not in correlation with the starting systems' quality.

关键词： optimization process optimization algorithm contrast function optical design

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Applications of uncertainty analysis to architecture selection of satellite systems

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JOURNAL OF SPACECRAFT AND ROCKETS 2004年第1期41卷 75-84页

作者： Walton, MA Hastings, DE MIT Cambridge MA 02139 USA

One of the most significant challenges in conceptual design is managing the tradespace of potential architectures: choosing which design to pursue aggressively, which to keep on the table, and which to leave behind. The application is presented of a framework for managing a tradespace of architectures not through traditional effectiveness 14 measures such as cost and performance, but instead through a quantitative analysis of the embedded uncertainty in each potential space system architecture. Cost and performance in this approach remain central themes in decision making, but uncertainty serves as the focal lens to identify potentially powerful combinations of architectures to explore concurrently in further design phases.

关键词： Satellite Constellations Standard Deviation Space Systems Architecture Moving Target Indication Ionosphere Medium Earth Orbit optimization algorithm Cost Estimate Constellations Yaw

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Evaluating the cost and risk impacts of launch choices

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JOURNAL OF SPACECRAFT AND ROCKETS 2004年第1期41卷 103-110页

作者： Weigel, AL Hastings, DE MIT Dept Aeronaut & Astronaut & Engn Cambridge MA 02139 USA

A method is presented for quantitatively assessing the generalized cost and risk impacts to a space system architecture of a restrictive government launch policy and application is made to the case of the U.S. space transportation policy of 1994. For both a restrictive and unrestrictive launch policy scenario, a mixed integer optimization algorithm is used to select the best launch vehicle suite for a given satellite system architecture based on the cost or risk selection rule for a particular type of decision maker. The cost and risk impacts that result in the two scenarios are compared over an extensive matrix of satellite masses, altitudes, inclinations, and constellation arrangements. Generalized launch policy cost impact estimating relationships are derived, and risk impacts are represented by descriptive statistics. The analysis finds that the 1994 U.S. launch policy affects the launch cost and launch risk of many types of satellite system architectures.

关键词： Satellite Constellations Launch Vehicles Launch Costs National Security Space Space Systems Architecture optimization algorithm Constellations Medium Earth Orbit Global Positioning System Space Stations

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PACE: A new approach to dynamic voltage scaling

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IEEE TRANSACTIONS ON COMPUTERS 2004年第7期53卷 856-869页

作者： Lorch, JR Smith, AJ Microsoft Corp Res Redmond WA 98052 USA Univ Calif Berkeley Dept Elect Engn & Comp Sci Div Comp Sci Berkeley CA 94720 USA

By dynamically varying CPU speed and voltage, it is possible to save significant amounts of energy while still meeting prespecified soft or hard deadlines for tasks;numerous algorithms have been published with this goal. We show that it is possible to modify any voltage scaling algorithm to minimize energy use without affecting perceived performance and present a formula to do so optimally. Because this formula specifies increased speed as the task progresses, we call this approach PACE (Processor Acceleration to Conserve Energy). This optimal formula depends on the probability distribution of the task's work requirement and requires that the speed be varied continuously. We therefore present methods for estimating the task work distribution and evaluate how effective they are on a variety of real workloads. We also show how to approximate the optimal continuous schedule with one that changes speed a limited number of times. Using these methods, we find we can apply PACE practically and efficiently. Furthermore, PACE is extremely effective: Simulations using real workloads and the standard model for energy consumption as a function of voltage show that PACE can reduce the CPU energy consumption of existing algorithms by up to 49.5 percent, with an average of 20.6 percent, without any effect on perceived performance. The consequent PACE-modified algorithms reduce CPU energy consumption by an average of 65.4 percent relative to no dynamic voltage scaling, as opposed to only 54.3 percent without PACE.

关键词： dynamic voltage scaling energy management power management optimization algorithm

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Optimized loading for particle-in-cell gyrokinetic simulations

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CANADIAN JOURNAL OF PHYSICS 2004年第8期82卷 609-622页

作者： Lewandowski, JLV Princeton Univ Plasma Phys Lab Princeton NJ 08543 USA

The problem of particle loading in particle-in-cell gyrokinetic simulations is addressed using a quadratic optimization algorithm. Optimized loading in configuration space dramatically reduces the short-wavelength modes in the electrostatic potential that are partly responsible for the nonconservation of total energy;further, the long-wavelength modes are resolved with good accuracy. As a result, the conservation of energy for the optimized loading is much better that the conservation of energy for the random loading. The method is valid for any geometry and can be coupled to optimization algorithms in velocity space.

关键词： .Optimized velocity space energy conservation long-wavelength short-wavelength markers optimization algorithm random loading nonconservation of total PIC gyrokinetic

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Design of a film surface roughness-minimizing molecular beam epitaxy process by reduced-order modeling of epitaxial growth

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JOURNAL OF APPLIED PHYSICS 2004年第2期95卷 483-489页

作者： Gallivan, MA Atwater, HA CALTECH Thomas J Watson Lab Appl Phys Pasadena CA 91125 USA

Molecular beam epitaxy of germanium was used along with kinetic Monte Carlo simulations to study time-varying processing parameters and their effect on surface morphology. Epitaxial Ge films were deposited on highly oriented Ge(001) substrates, with reflection high-energy electron diffraction as a real-time sensor. The Monte Carlo simulations were used to model the growth process, and physical parameters were determined during growth under time-varying flux. A reduced version of the simulations was generated, enabling the application on an optimization algorithm. Temperature profiles were then computed that minimize surface roughness subject to various experimental constraints. The final roughness after two layers of growth was reduced to 0.32, compared to 0.36 at the maximum growth temperature. The study presented here is an initial demonstration of a general approach that could also be used to optimize properties in other materials and deposition processes. (C) 2004 American Institute of Physics.

关键词： .epitaxial growth surface morphology reduced-order molecular beam epitaxy optimization algorithm physical parameters time-varying

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Universal equation of state for engineering application: algorithm and application to non-polar and polar fluids

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FLUID PHASE EQUILIBRIA 2004年第222期222卷 107-118页

作者： Sun, LX Ely, JF Colorado Sch Mines Dept Chem Engn Golden CO 80401 USA

Engineering equations of state (EOS) deal with the majority of fluids of interest in process and equipment design in the chemical industries. Accuracy and universality are two desirable features the engineering EOS require, however, both of them cannot be simultaneously obtained without some degree of compromise. Therefore a simultaneous optimization algorithm is proposed to develop an accurate but compact engineering EOS for wide range of fluids with one single functional form. The algorithm is based on a simulated annealing method, and operates on different fluids at the same time to achieve the best average results. A 14-term EOS is developed based on this algorithm that has good accuracy for selected non-polar and polar fluids. The resulting equation is compared with two different 12-term EOS developed by Span and Wagner, one for polar fluids, the other for non-polar fluids. The new 14-term EOS also gives good predictions for some associating fluids such as alcohols and water. (C) 2004 Elsevier B.V. All rights reserved.

关键词： equation of state optimization algorithm non-polar and polar fluids associating fluids thermodynamic properties

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A new approach for constructing match wavelet to signal detection

A new approach for constructing match wavelet to signal dete...

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International Conference on Communications, Circuits and Systems

作者： Shi, GM Ding, AL Jiao, LC Xidian Univ Sch Elect Engn Xian 710071 Peoples R China

ISBN: (纸本)0780386477

This paper proposed a technique for constructing a wavelet matched to given signal. The design of match wavelet can be formulated as finding a minimal or maximal projection of given signal on to scaling subspace. The key development is to construct match wavelet by structural filter bank of wavelet rather than by scaling function. The method can reduce the cost of calculation when decomposed signal by wavelet. The design procedures for match wavelet and an example for matching to ultrasound echo are also presented.

关键词： match wavelet filter banks optimization algorithm

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Applications Of Robust Control To Nonlinear Systems

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丛书名： Progress in Astronautics and Aeronautics

2004年

作者： Richard Colgren

ISBN: (数字)9781600866722

ISBN: (纸本)9781563476662

This book offers a three-step approach to generating a robust nonlinear controller: modeling, synthesis, and robustness analysis. The publication is targeted to practicing engineers and graduate-level students working in guidance, information command and control systems, and CAD/*** methods covered in this book allow the user to design and analyze nonlinear controllers for nonlinear systems with several important and unique characteristics: the ability to specify the closed loop system's frequency response via requirements on the sensitivity (S) and complementary sensitivity (T), the ability to directly minimize an undesirable resonance or peak in the frequency response while simultaneously closing all loops from the input to the output vector in essentially one single design step, and the ability to analyze the stability characteristics for multiple independent and dependent problem variables. The approach uniquely allows the user to achieve stable and robust performance for systems which are both unstable and contain discontinuous nonlinearities using adaptive nonlinear controllers.

关键词： Aerodynamics Aeronautical Engineering Aeronautics Aerospace Electronics Aerospace Engineering Aerospace Sciences Air Forces Aircraft Control Aircraft Design Aircraft Dynamic Modes Aircraft Flight Control System Aircraft Operations Aircraft Operations and Technology Aircraft Performance Aircraft Stability and Control Aircraft Wing Design Aircrafts algorithms and Data Structures Applied Mathematics Autonomous Systems Aviation Avionics Avionics Computers Civil Aircraft Computer Networks Computer Programming and Language Computing and Informatics Computing, Information, and Communication Control Systems Control Theory Data Science Electrical Measuring Equipment Electricity Electromagnetism Elementary Algebra Feedback Control Flight Control Surfaces Flight Dynamics Flight Training Flying Qualities General Physics Guidance, Navigation, and Control Systems Inverse Problems Military Aviation Multivariable Control Nonlinear Control Theory Optimal Control Theory optimization algorithm Riccati Equations Search algorithm Signal Processing

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Universal equation of state for engineering application: algorithm and application to non-polar and polar fluids

Universal equation of state for engineering application: alg...

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15th Symposium on Thermophysical Properties

作者： Sun, LX Ely, JF Colorado Sch Mines Dept Chem Engn Golden CO 80401 USA

关键词： equation of state optimization algorithm non-polar and polar fluids associating fluids thermodynamic properties

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