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2nd International Conference on Power Electronics Systems and Applications

作者： Yanbo, Che Liyun, Liu Cheng, K. W. Eric Tianjin Univ Sch Elect Engn & Automat Tianjin 300072 Peoples R China Hong Kong Polytech Univ Dept Elect Engn Hong Kong Hong Kong Peoples R China

ISBN: (纸本)9789623675444

In order to minimize the volume of HTS magnets and reduce the perpendicular component of magnetic field, two optimal algorithms- iterative algorithm and genetic algorithm are presented to make optimal design of geometry parameter of HTS magnets. The example of optimal design of 500kJ HTS magnet is also given. And the comparison between iterative algorithm and genetic algorithm has done. The iterative algorithm is a optimal method which magnet performance varies with numbers of solenoid coil layer. The magnet geometry parameters should be determined with a rule of heightening the magnet performances and the minimum of magnet volume is found. The improved GA is applied well in magnet optimal design combining Britaina Sheffield University GA toolbox and the optimal results are obtained.

关键词： HTS magnets optimal design minimum of volume iterative algorithm genetic algorithm(GA)

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Free-Space Permittivity Measurement for Inhomogeneous PSV-Coated Si-wafer at Frequencies from 75 GHz to 325 GHz

Free-Space Permittivity Measurement for Inhomogeneous PSV-Co...

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6th IEEE MTT-S International Wireless Symposium (IWS) part of China Microwave Week

作者： Jung, Sohyeon Choo, Moogoong Lee, Jae-Yeong Ahn, In-sung Lee, Kangseop Hong, Wonbin Pohang Univ Sci & Technol POSTECH Pohang 37673 South Korea

ISBN: (纸本)9781728107165

A method to extract dielectric property of inhomogeneous PSV (Passivation)-coated Si-wafer is presented at broadband frequencies from 75 GHz to 325 GHz. Free-space measurement using continuous wave (CW) system is carried out. Numerical iterative algorithm is employed to extract permittivity from complex scattering parameters. Due to scarcity of related previous studies beyond 100 GHz, the discussions on parameters that may affect the results are also described in detail. The calculated permittivity based on the proposed method highly correlates with the analytical values.

关键词： complex permittivity free-space transmission measurement fabry-Perot effect inhomogeneous material iterative algorithm passivation material

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Optical Fish Estimation and Detection in Noisy Environment

Optical Fish Estimation and Detection in Noisy Environment

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Oceans Conference

作者： Boudhane, Mohcine Badri-Hoeher, Sabah Nsiri, Benayad Univ Appl Sci Fac Comp Sci & Elect Engn Grenzstr 5 D-24149 Kiel Germany Univ Hassan 2 Fac Sci Casablanca 20000 Morocco

ISBN: (纸本)9781479949182

Detecting fish in submarine environment is a challenge due to the properties of the water such as light absorption and scattering. In this work, we present a method for preprocessing images in submarine environment. In the first step, we model the underwater environment as overlapp of two processes. The first process is considered as a Poisson distribution, while the second one is considered as a Gaussian mixture. The resulting distribution is called Poisson-Gaussian mixture (PGM). To estimate the noise parameters, we propose an iterative algorithm based on the expectation maximization approach. This allows us to jointly estimate the scale of the Poisson parameter as well as the standard deviation and the mean of all Gaussian distributions. In order to facilitate the detection of objects, to correct the illumination problem of the scene and to restore the colors, we integrate a color correction algorithm. Finally, detection and localization of fish complete the pre-processing in the images. To obtain medium or small regions, the mean shift algorithm is used with a reduced threshold. In the segmentation process, the proposed detector scan the image region by region. This detector allows to estimate statistically the type of the region (object or non-object). The method is tested under different underwater conditions. Experimental results show that the proposed approach outperforms conventional methods.

关键词： Gaussian processes Poisson distribution expectation-maximisation algorithm geophysical image processing image restoration image segmentation iterative methods light absorption light scattering object detection oceanographic techniques underwater optics Poisson parameter Poisson-Gaussian mixture color correction algorithm expectation maximization approach fish localization illumination problem image preprocessing iterative algorithm mean shift algorithm noise parameters noisy submarine environment optical fish detection optical fish estimation segmentation process standard deviation underwater conditions underwater environment water properties Colored noise Estimation Image color analysis Image segmentation PSNR Underwater vehicles

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A Fast Analytic Multiple-Sources Angle-of-Arrival Estimation algorithm for Automotive MIMO Radars

A Fast Analytic Multiple-Sources Angle-of-Arrival Estimation...

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IEEE International Symposium on Antennas and Propagation / North American Radio Science Meeting

作者： Cai, Xiuzhang Sarabandi, Kamal Univ Michigan Elect Engn & Comp Sci Dept Ann Arbor MI 48109 USA

ISBN: (纸本)9781728166704

Traditionally, the angle of arrival (AOA) estimation problem for multiple sources is considered as a nonlinear problem with no analytic solutions. In this paper, an analytic iterative multiple-source AOA algorithm (AIMA) is presented for fast and accurate estimation of the AOA. The approach is most useful for automotive MIMO radars where there can be a large number of scatterers in the scene. The AOA estimation problem is divided into two main tasks: (1) estimate one AOA with the prior knowledge of all other AOA;(2) estimate all AOA by iteratively solving Task 1. It can be shown that for a uniform linear array (ULA) Task 1 has analytic solutions and Task 2 converges very fast, which makes this method effective, efficient and practical for real-time processing. Unlike many other AOA estimation methods, this approach doesn't need the information about the number of sources and can be applied for coherent signals and single snapshot as well.

关键词： angle of arrival direction of arrival iterative algorithm

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A dynamic component model for forecasting high-dimensional realized covariance matrices

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ECONOMETRICS AND STATISTICS 2017年 1卷 40-61页

作者： Bauwens, Luc Braione, Manuela Storti, Giuseppe Catholic Univ Louvain CORE B-1348 Louvain La Neuve Belgium Univ Cote dAzur SKEMA Nice France Univ Salerno Dipartimento Sci Econ & Stat DISES Via Giovannni Paolo 2132 I-84084 Fisciano SA Italy

The Multiplicative MIDAS Realized DCC (MMReDCC) model simultaneously accounts for short and long term dynamics in the conditional (co)volatilities of asset returns, in line with the empirical evidence suggesting that their level is changing over time as a function of economic conditions. Herein the applicability of the model is improved along two directions. First, by proposing an algorithm that relies on the maximization of an iteratively re-computed moment-based profile likelihood function and keeps estimation feasible in large dimensions by mitigating the incidental parameter problem. Second, by illustrating a conditional bootstrap procedure to generate multi-step ahead predictions from the model. In an empirical application on a dataset of forty-six equities, the MMReDCC model is found to statistically outperform the selected benchmarks in terms of in-sample fit as well as in terms of out-of-sample covariance predictions. The latter are mostly significant in periods of high market volatility. (c) 2016 ECOSTA ECONOMETRICS AND STATISTICS. Published by Elsevier B.V. All rights reserved.

关键词： Realized covariance dynamic component models multi-step forecasting iterative algorithm

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New System of Quasi-variational-like Inclusions Involving monotone Operators in General Banach Spaces

New System of Quasi-variational-like Inclusions Involving mo...

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International Forum on Information Technology and Applications (IFITA 2009)

作者： Ni Renxing Shaoxing Univ Dept Math Shaoxing 313000 Zhejiang Peoples R China

ISBN: (纸本)9780769536002

A new system of set-valued quasi-variational-like inclusions (in short,QVLI) involving H-n-monotone operators is introduced and studied in general Banach spaces without uniform smoothness. Moreover, A new iterative algorithm to find the approximation solutions of the QVLI is suggested and analyzed. It is proved that the iterative sequences generated by the algorithm converge strongly to the exact solution of the QVLI under suitable assumptions. These new results extend and improve the corresponding ones in this field.

关键词： iterative algorithm new system of set-valued quasi-variational-like inclusions H-n-monotone operator resolvent operator technique

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A hierarchical two-level spectral preconditioning technique for cavity scattering problems

A hierarchical two-level spectral preconditioning technique ...

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International Conference on Microwave and Millimeter Wave Technology

作者： Chen, M. Ding, D. Z. Fan, Z. H. Chen, R. S. Yung, Edward K. N. Nanjing Univ Sci & Technol Dept Elect Engn Nanjing Peoples R China

ISBN: (纸本)9781424418794

A new set of higher order hierarchical basis functions is proposed for expansion of the current in electrical field integral equations (EFIE) solved by multilevel fast multipole algorithm (MLFMA) for the cavity scattering problem. The hierarchical two-level spectral preconditioning technique is developed to solve EFIE with multiple right-hand sides arising in monostatic radar cross section (RCS) calculations. The sparse approximate inverse (SAI) preconditioner based on the higher order hierarchical basis functions is used to damp the high frequencies of the error and the low frequencies is eliminated by a spectral preconditioner in a two-level manner defined on the lower order basis functions. The spectral preconditioner is combined with SAI preconditioner to obtain a hierarchical two-level spectral preconditioner. This newly constructed hierarchical two-level spectral preconditioner is used to speed up the restarted GMRES iterative algorithm. Numerical experiments indicate that the new preconditioner is efficient for the MLFMA and can significantly reduce both the iteration number and computational time.

关键词： cavity resonators integral equations iterative methods radar cross-sections cavity scattering electrical field integral equation hierarchical basis function iteration number iterative algorithm monostatic radar cross section multilevel fast multipole alg

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Stability of an iterative multiwavelength lidar scheme

Stability of an iterative multiwavelength lidar scheme

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Conference on Laser Radar Technology for Remote Sensing

作者： Vargas, M Gross, B Moshary, F Ahmed, S CUNY City Coll Opt Remote Sensing Lab New York NY 10031 USA

ISBN: (纸本)0819451231

Multiwavelength elastic lidar is often used to probe the aerosol profiles of the atmosphere. Normally, the atmosphere is considered homogeneous and an a-priori aerosol ratio is given for each wavelength channel which is then processed independently. However, it is clear that the multiwavelength retrieved backscatter profiles should contain information that can be used to estimate particle size distribution which may provide a new estimate to range dependant aerosol ratio profiles which can be repeated until convergence. In this paper, we illustrate the basic idea of using multiwavelength data using a two wavelength lidar to obtain local information on the lidar ratio which can be used to improve lidar profiling in inhomogeneous atmospheres and show that a key feature of any scheme is the monotonic dependance between the optical data ratio and the distribution parameter. In addition. we extend the approach to a prototypical Nd:YAG three wavelength (355, 532, 1064 nm) lidar arrangement and show that while an iterative lidar procedure can be used to extract range dependant profiles, imprecision in the inversion procedure as well as error propagation of the lidar back integration can hamper convergence.

关键词： elastic lidar multwavelength iterative algorithm

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Low-Complexity Channel Estimation Based on Weighted Kapteyn Series Expansion for Massive MIMO Systems 9

Low-Complexity Channel Estimation Based on Weighted Kapteyn ...

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9th International Conference on Wireless Communications and Signal Processing (WCSP)

作者： Li, Zhengquan Wang, Bing Sun, Yaoyao Yan, Feng Xing, Song Shen, Lianfeng Southeast Univ Natl Mobile Commun Res Lab Nanjing 210096 Jiangsu Peoples R China Beijing Univ Posts & Telecommun State Key Lab Networking & Switching Technol Beijing 100876 Peoples R China Calif State Univ Los Angeles Dept Informat Syst Los Angeles CA 90032 USA

ISBN: (纸本)9781538620625

An improved MMSE method aimed to reduce the computational burden is proposed in this paper. In the method, the covariance matrix inversion is approximated by the expansion of N-order polynomials of weighted Kapteyn series which has low truncation errors. In this method, an unconstrained non-linear optimization model is established and an iterative algorithm based on coordinate rotation is used to solve this problem. Analysis and numerical results show that the mean square error (MSE) of our proposed weighted Kapteyn-MMSE estimation approaches MMSE performance quickly when the series order of N is increasing, while the computational complexity of this method is significantly reduced. And the proposed method improves the convergence to ordinary MMSE performance when compared to traditional Taylor-MMSE estimator or Kapteyn-MMSE, which means the latter needs a higher N-order than the former to approach MMSE estimation.

关键词： Channel Estimation Massive MIMO Kapteyn Series Polynomial Expansion iterative algorithm

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Information Theoretic Optimal Broadband Matching for Communication Systems

Information Theoretic Optimal Broadband Matching for Communi...

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IEEE Global Telecommunications Conference (GLOBECOM 2010)

作者： Taluja, Pawandeep S. Hughes, Brian L. N Carolina State Univ Dept Elect & Comp Engn Raleigh NC 27695 USA

ISBN: (纸本)9781424456383

We present an information theoretic perspective on optimal broadband matching. Most of the broadband matching and communication theory literature assumes a frequency-flat reflection coefficient. We derive the optimal capacity and matching network characteristic for a broadband system from an information theoretic view point while incorporating the broadband matching limitations. We also propose an iterative algorithm to arrive at the optimal solution. We illustrate by an example that a white characteristic for a matching network is often sub-optimal for a system with a non-white transfer function.

关键词： MIMO communication MIMO systems communication systems communication theory frequency-flat reflection coefficient information theoretic optimal broadband matching iterative algorithm iterative methods matching network characteristic nonwhite transfer funct

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