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Data Compression Conference (DCC)

作者： Reznik, Yuriy A. Qualcomm Inc San Diego CA 92121 USA

ISBN: (纸本)9780769543529

We study the problem of quantization of discrete probability distributions, arising in universal coding, as well as other applications. We show, that in many situations this problem can be reduced to the covering problem for the unit simplex, yielding precise characterization in the high-rate regime. Our main contribution is a simple and asymptotically optimal algorithm for solving this problem. Performance of this algorithm is studied and compared with several known solutions.

关键词： covering radius enumeration of types lattice quantization source coding two-step codes types unversal coding Quantization Probability distribution source coding crystal lattices statistical distribution optimization algorithms universal coding

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DEVELOPMENT AND VERIFICATION OF A COMPUTATIONAL FLUID DYNAMICS MODEL OF A HORIZONTAL-AXIS TIDAL CURRENT TURBINE

DEVELOPMENT AND VERIFICATION OF A COMPUTATIONAL FLUID DYNAMI...

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30th International Conference on Ocean, Offshore and Arctic Engineering

作者： Lawson, Michael J. Li, Ye Sale, Danny C. Natl Wind Technol Ctr Natl Renewable Energy Lab Golden CO 80401 USA Univ Washington Mech Engn Dept Seattle WA 98195 USA

ISBN: (纸本)9780791844373

This paper describes the development of a computational fluid dynamics (CFD) methodology to simulate the hydrodynamics of horizontal-axis tidal current turbines (HATTs). First, an HATT blade was designed using the blade element momentum method in conjunction with a genetic optimization algorithm. Several unstructured computational grids were generated using this blade geometry and steady CFD simulations were used to perform a grid resolution study. Transient simulations were then performed to determine the effect of time-dependent flow phenomena and the size of the computational timestep on the numerical solution. Qualitative measures of the CFD solutions were independent of the grid resolution. Conversely, quantitative comparisons of the results indicated that the use of coarse computational grids results in an under prediction of the hydrodynamic forces on the turbine blade in comparison to the forces predicted using more resolved grids. For the turbine operating conditions considered in this study, the effect of the computational timestep on the CFD solution was found to be minimal, and the results from steady and transient simulations were in good agreement. Additionally, the CFD results were compared to corresponding blade element momentum method calculations and reasonable agreement was shown. Nevertheless, we expect that for other turbine operating conditions, where the flow over the blade is separated, transient simulations will be required.

关键词： Resolution (Optics) Geometry Tides Turbines Flow (Dynamics) Blades Engineering simulation Simulation Turbine blades Hydrodynamics optimization algorithms Computational fluid dynamics Fluid-dynamic forces Transients (Dynamics) Momentum

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SEMI-SUPERVISED SELF-TRAINING MODEL FOR THE SEGMENTATION OF THE LEFT VENTRICLE OF THE HEART FROM ULTRASOUND DATA

SEMI-SUPERVISED SELF-TRAINING MODEL FOR THE SEGMENTATION OF ...

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8th IEEE International Symposium on Biomedical Imaging (ISBI) - 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 Fernand Fonseca Dept Cardiol Amadora Portugal

ISBN: (纸本)9781424441280

The design and use of statistical pattern recognition models can be regarded as one of the core research topics in the segmentation of the left ventricle of the heart from ultrasound data. These models trade a strong prior model of the shape and appearance of the left ventricle for a statistical model whose parameters can be learned using a manually segmented data set (this set is commonly known as the training set). The trouble is that such statistical model is usually quite complex, requiring a large number of parameters that can be robustly learned only if the training set is sufficiently large. The difficulty in obtaining large training sets is currently a major roadblock for the further exploration of statistical models in medical image analysis problems, such as the automatic left ventricle segmentation. In this paper, we present a novel semi-supervised self-training model that reduces the need of large training sets for estimating the parameters of statistical models. This model is initially trained with a small set of manually segmented images, and for each new test sequence, the system re-estimates the model parameters incrementally without any further manual intervention. We show that state-of-the-art segmentation results can be achieved with training sets containing 50 annotated examples for the problem of left ventricle segmentation from ultrasound data.

关键词： Segmentation of the left ventricle of the heart semi-supervised training self-training deep neural networks optimization algorithms

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The Tooth Form Deviation Correction of CNC Spiral Bevel Gears Grinding Machine

The Tooth Form Deviation Correction of CNC Spiral Bevel Gear...

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International Conference on Power Transmission

作者： Zhang, Weiqing Guo, Xiaodong Zhang, Mingde Chongqing Univ Technol Key Lab Manufacture & Test Tech Automobile Parts Minist Educ Chongqing Peoples R China

ISBN: (纸本)9783037852330

The influencing factors of machining errors are analyzed aiming at the characteristics of the CNC spiral bevel gears grinding machine. The relation between those factors and machine setting errors is built. The optimization model of nonlinear least square is deduced. According to the mathematics model, an experiment of tooth form deviation correction is done in YK2075 CNC spiral bevel gears grinding machine manufactured by Tianjin No.1 Machine Tool Works. And the mathematics model is verified in the experiment.

关键词： bevel gears gear grinding machine optimization algorithms deviation correction

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Language and Compiler Support for Auto-Tuning Variable-Accuracy algorithms

Language and Compiler Support for Auto-Tuning Variable-Accur...

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9th Annual IEEE/ACM International Symposium on Code Generation and optimization (CGO)

作者： Ansel, Jason Wong, Yee Lok Chan, Cy Olszewski, Marek Edelman, Alan Amarasinghe, Saman MIT Comp Sci & Artificial Intelligence Lab Cambridge MA 02139 USA

ISBN: (纸本)9781612843551

Approximating ideal program outputs is a common technique for solving computationally difficult problems, for adhering to processing or timing constraints, and for performance optimization in situations where perfect precision is not necessary. To this end, programmers often use approximation algorithms, iterative methods, data resampling, and other heuristics. However, programming such variable accuracy algorithms presents difficult challenges since the optimal algorithms and parameters may change with different accuracy requirements and usage environments. This problem is further compounded when multiple variable accuracy algorithms are nested together due to the complex way that accuracy requirements can propagate across algorithms and because of the size of the set of allowable compositions. As a result, programmers often deal with this issue in an ad-hoc manner that can sometimes violate sound programming practices such as maintaining library abstractions. In this paper, we propose language extensions that expose trade-offs between time and accuracy to the compiler. The compiler performs fully automatic compile-time and install-time autotuning and analyses in order to construct optimized algorithms to achieve any given target accuracy. We present novel compiler techniques and a structured genetic tuning algorithm to search the space of candidate algorithms and accuracies in the presence of recursion and sub-calls to other variable accuracy code. These techniques benefit both the library writer, by providing an easy way to describe and search the parameter and algorithmic choice space, and the library user, by allowing high level specification of accuracy requirements which are then met automatically without the need for the user to understand any algorithm-specific parameters. Additionally, we present a new suite of benchmarks, written in our language, to examine the efficacy of our techniques. Our experimental results show that by relaxing accuracy requirement

关键词： required precision Language compilers Self tuning algorithms optimization algorithms Recursion

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Electimize: New Evolutionary Algorithm for optimization with Application in Construction Engineering

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JOURNAL OF COMPUTING IN CIVIL ENGINEERING 2011年第3期25卷 192-201页

作者： Khalafallah, Ahmed Abdel-Raheem, Mohamed Univ Cent Florida Dept Civil Environm & Construct Engn Orlando FL 32816 USA

In nonlinear construction optimization problems, the capability of current optimization algorithms to find an optimal solution is usually limited by their inability to evaluate the effects of changing the value of each decision variable on reaching the optimal solution. This paper presents fundamental research aimed at developing a novel evolutionary optimization algorithm, named Electimize, that mimics the behavior of electrons flowing, through electric circuit branches with the least electric resistance. In the proposed algorithm, solutions are represented by electric wires and are evaluated on two levels: a global level, using the objective function, and a local level, evaluating the potential of each generated value for every decision variable. The paper presents (1) the research philosophy and scope, (2) the research methodology, and (3) the development of the algorithm. The proposed algorithm has been validated and applied successfully to an NP-hard cash flow optimization problem. The algorithm was able to find a better optimal solution and identified ten alternative optimal solutions for the same problem. This should prove useful in enhancing the optimization of complex large-scale problems. DOI: 10.1061/(ASCE)CP.19435487.0000080. (C) 2011 American Society of Civil Engineers.

关键词： optimization algorithms Construction Cash flow

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Rate-Allocation for Spatially Scalable Video Coding

Rate-Allocation for Spatially Scalable Video Coding

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7th International Symposium on Image and Signal Processing and Analysis (ISPA)

作者： Peng, Guan-Ju Hwang, Wen-Liang Chen, Sao-Jie Acad Sinica Inst Informat Sci Taipei Taiwan Natl Taiwan Univ Grad Inst Elect Engn Taipei Taiwan

ISBN: (纸本)9789531841597

In this paper, we analyze the distortion propagation of temporal and spatial prediction in scalable video coding (SVC) and show that the average peak-signal-to-noise (PSNR) of SVC is a weighted combination of the bit rates assigned to all the layers. Our analysis utilizes the end user's preference for certain resolutions. In addition, we propose the rate-distortion optimization algorithm, which employs the known user preference. The results of experiments on H.264/SVC demonstrate that the algorithms outperform the approach proposed in [1], [2].

关键词： scalable video coding Bit rate Static VAr compensators User preferences optimization algorithms Video coding Peak signal-to-noise ratio Rate distortion End users

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Harmony Search Method for Multimodal Size, Shape, and Topology optimization of Structural Frameworks

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JOURNAL OF STRUCTURAL ENGINEERING-ASCE 2011年第11期137卷 1332-1339页

作者： Martini, Kirk Univ Virginia Dept Architecture Charlottesville VA 22904 USA

This paper describes and demonstrates modifications of the harmony search method to support multimodal structural optimization. Several researchers have recognized the potential of population-based optimization methods, such as genetic algorithms and particle swarm optimization, to support multimodal optimization, that is, generating a range of good alternative solutions, rather than a single best solution. Among these population-based methods is the harmony search method, which has been demonstrated to be efficient and effective in many unimodal structural optimization problems. Toward the goal of making the harmony search method more effective in multimodal optimization, this paper describes a new strategy for generating solutions called close-harmony improvisation, and a new strategy for replacing solutions called local replacement. Examples demonstrate the effect of the two strategies used individually and in tandem. The discussion compares results with conventional harmony search and finds that close-harmony improvisation consistently improves the fitness of the search results, although the effect is sometimes mild, whereas local replacement is quite effective in increasing the diversity of the search result. DOI: 10.1061/(ASCE)ST.1943-541X.0000378. (C) 2011 American Society of Civil Engineers.

关键词： optimization algorithms Structural design

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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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22nd IEEE International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC)

作者： Gupta, Rohit Strinati, Emilio Calvanese CEA LETI MINATEC F-38054 Grenoble France

ISBN: (纸本)9781457713484

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 down link 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 trade off 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 through put 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 Scheduling algorithms Transmitter power Power consumption Energy sources Downlink optimization algorithms

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Knowledge management in the development of optimization algorithms

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Symposium on Human Interface held at the HCI International 2007

作者： Crawford, Broderick Castro, Carlos Monfroy, Eric Pontificia Univ Catolica Valparaiso Valparaiso Chile

ISBN: (纸本)9783540733447

This paper captures our experience developing algorithms to solve Combinatorial Problems using different techniques. Because it is a Software Engineering problem, then to find better ways of developing algorithms, solvers and metaheuristics is our interest too. Here, we fixed some concepts from Knowledge Management and Software Engineering applied in our work.

关键词： knowledge management software engineering agile development creativity optimization algorithms

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