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Improved iterative algorithm for the three-flat test

OPTICAL ENGINEERING 2014年第9期53卷 092004-092004页

作者： Gao, Bo Li, Qiang He, Yuhang Chai, Liqun Fine Opt Engn Res Ctr Chengdu 610041 Peoples R China

An iterative algorithm has been successfully used to process data from the three-flat test. On the basis of the iterative algorithm proposed by Vannoni, which is much faster and more effective than the Zernike polynomial fitting method, an improved algorithm is presented. By optimizing the iterative steps and removing the scaling factors, the surface shape can be easily computed in a few iterations. The validity of the method is proved by computer simulation, and the interpolation error and principle error are analyzed. (C) The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License.

关键词： three-flat test iterative algorithm computer simulation

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Research on the multi-parameter identification of thermal-acoustic-solid coupling problem in an inhomogeneous medium

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JOURNAL OF MATHEMATICAL ANALYSIS AND APPLICATIONS 2023年第2期521卷

作者： Zhu, Liyan Cui, Yue Du, Yanxia Wei, Dong Deng, Youjun Cent South Univ Changsha Sch Math & Stat HNP LAMA Changsha 410083 Hunan Peoples R China China Aerodynam Res & Dev Ctr Mianyang Mianyang 621000 Sichuan Peoples R China

This work considers the multi-parameter identification problem in initial-boundary values of variable coefficient coupled partial differential equations. Based on ultrasonic echo time measurements, we identify the surface heat flux and thickness simultaneously, and then achieve the reconstruction of the internal transient temperature field. Through rigorous theoretical analysis, we show the uniqueness recovery result for the multiparameter identification problem. By reformulating the inverse problem as an optimization problem, we propose an efficient alternating iteration algorithm in solving the related optimization problem and provide a rigorous convergence analysis of the algorithm. Finally, the reliability and feasibility of this algorithm are verified by some numerical examples.(c) 2022 Elsevier Inc. All rights reserved.

关键词： Multi-parameter identification Inhomogeneous medium Uniqueness iterative algorithm

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Analytics and Optimization Techniques on Feeder Identification in Smart Grids 19

Analytics and Optimization Techniques on Feeder Identificati...

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19th International Conference on Smart Technologies (IEEE EUROCON)

作者： Aranburu, Larraitz Unzueta, Aitziber Garin, M. Araceli Modrono, Juan, I Amezua, Aitor Univ Basque Country Dept Matemat Leioa Bizkaia Spain Univ Basque Country Dept Matemat Aplicada Blbao Bizkaia Spain Univ Basque Country Dept Metodos Cuantitat Blbao Bizkaia Spain Univ Basque Country Dept Metodos Cuantitat Bilbao Bizkaia Spain ZIV Automat Zamudio Bizkaia Spain

ISBN: (纸本)9781665432993

One of the problems faced by electric power distribution system operators is to know with certainty the actual location of all their assets in order to manage properly the grid and provide the best service to their customers. In this work, we present a procedure for the identification of low voltage feeders or distribution lines in smart grids that is based on the mathematical formulation of the problem as an optimization model. In particular, we define the model with 0-1 variables (as many as meters to be identified in the different feeders) and with as many restrictions as the number of points in time that are considered. Given the large size of the problem in practice, the use of conventional optimization software becomes unfeasible. Based on this approach, and making use of the linear relaxation of the problem, some analytics over the coefficients (i.e., meter loads) and the special structure of the problem itself, we have developed an iterative procedure that allows us to recover the entire solution of the initial model in an efficient way. We have carried out a computational experience on a set of anonymized real data, obtaining results that support the efficiency of the proposed procedure.

关键词： connectivity model integer optimization iterative algorithm linear relaxation smart meter datasets

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IMPROVED SELF-ADAPTIVE iterative algorithmS FOR THE SPLIT EQUALITY COMMON FIXED-POINT PROBLEM OF FIRMLY QUASI-NONEXPANSIVE OPERATORS

JOURNAL OF NONLINEAR FUNCTIONAL ANALYSIS

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JOURNAL OF NONLINEAR FUNCTIONAL ANALYSIS 2020年 2020卷

作者： Zhao, Jing Li, Yuan Zong, Haili Civil Aviat Univ China Coll Sci Tianjin 300300 Peoples R China

In this paper, we investigate the split equality common fixed-point problem of firmly quasi-nonexpansive operators in Hilbert spaces. We introduce new iterative algorithms with a way of selecting the step-sizes such that its implementation does not need any prior information about the operator norms. The new methods are extended from the method for solving the split common fixed-point problem. The range of the new step-sizes even can be enlarged two times. Under suitable conditions, we establish a weak convergence theorem of the proposed algorithm and a strong convergence theorem of its variant by the viscosity approximation method. Numerical results are reported to show the effectiveness of the proposed algorithm.

关键词： Split equality common fixed-point problem iterative algorithm Firmly quasi-nonexpansive operators Fejer-monotone Strong convergence

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A Novel Sensor-less On-line Estimation Method of IGBT Junction Temperature 12

A Novel Sensor-less On-line Estimation Method of IGBT Juncti...

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12th IEEE Energy Conversion Congress and Exposition-Asia (ECCE-Asia)

作者： Zhan, Cao Zhu, Lingyu Zhang, Yaxin Ji, Shengchang Zhang, Jian Yu, Chaoyun Xi An Jiao Tong Univ State Key Lab Elect Insulat & Power Equipment Xian Peoples R China China Southern Power Grid Technol Co LTD Guangzhou Peoples R China

ISBN: (纸本)9781728163444

Thermal management and condition monitoring of power converters demand the accurate estimation of the junction temperature of insulated-gate bipolar transistor (IGBT). With existing iteration methods, the junction temperature is fed forward to calculate the power loss and derive the junction temperature of the next cycle, causing the problem of accumulated calculation error. This letter proposes a novel iterative algorithm to improve the calculation accuracy. Unlike the conventional solutions, utilizing the junction temperature of the previous moment to calculate the power losses, the proposed iteration method uses junction temperature and power losses of the same moment to tackle the accumulated error problem. Since the iterative equation has unique solution, the convergence value is the actual junction temperature and power losses. The initial power losses has no influence on the result, so it is not necessary to obtain the accurate power loss for the estimation of junction temperature. Power cycling experiment is performed to verify the advantages of the novel iterative algorithm. The novel method solves the accumulated error compared to the traditional method. The accuracy of the novel method is also verified by the result of 100mA current test during power cycling.

关键词： IGBT junction temperature iterative algorithm power loss power cycling

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Optimizing Information Transfer Through Chemical Channels in Molecular Communication

Optimizing Information Transfer Through Chemical Channels in...

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IEEE Global Communications Conference (GLOBECOM)

作者： Ratti, Francesca Harper, Colton Magarini, Maurizio Pierobon, Massimiliano Politecn Milan Dipartimento Elettron Informaz & Bioingn I-120133 Milan Italy Univ Nebraska Dept Comp Sci & Engn Lincoln NE 68588 USA

ISBN: (纸本)9781728181042

The optimization of information transfer through molecule diffusion and chemical reactions is one of the leading research directions in Molecular Communication (MC) theory. The highly nonlinear nature of the processes underlying these channels poses challenges in adopting analytical approaches for their information-theoretic modeling and analysis. In this paper, a novel iterative methodology is proposed to numerically estimate achievable information rates. Based on the Nelder-Mead optimization, this methodology does not necessitate analytical formulations of MC components and their stochastic behavior, and, when applied to well-known scenarios, it demonstrates consistent results with theoretical bounds and superior performance to prior literature. A numerical example that abstracts communications between genetically engineered cells via simulation is presented and discussed in light of possible future applications to support the design and engineering of realistic MC systems.

关键词： Molecular Communication Chemical Reaction Channel Diffusion Channel iterative algorithm Mutual Information Achievable Information Rate

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EMPIRICALLY ACCELERATING SCALED GRADIENT PROJECTION USING DEEP NEURAL NETWORK FOR INVERSE PROBLEMS IN IMAGE PROCESSING

EMPIRICALLY ACCELERATING SCALED GRADIENT PROJECTION USING DE...

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IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP)

作者： Lee, Byung Hyun Chun, Se Young UNIST Grad Sch AI Seoul South Korea Seoul Natl Univ INMC Dept ECE Seoul South Korea

ISBN: (纸本)9781728176055

Recently, deep neural networks (DNNs) have shown advantages in accelerating optimization algorithms. One approach is to unfold finite number of iterations of conventional optimization algorithms and to learn parameters in the algorithms. However, these are forward methods and are indeed neither iterative nor convergent. Here, we present a novel DNN-based convergent iterative algorithm that accelerates conventional optimization algorithms. We train a DNN to yield parameters in scaled gradient projection method. So far, these parameters have been chosen heuristically, but have shown to be crucial for good empirical performance. In simulation results, the proposed method significantly improves the empirical convergence rate over conventional optimization methods for various large-scale inverse problems in image processing.

关键词： scaled gradient projection deep neural network iterative algorithm convergence

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Numerical Evaluations for Multiplicative Algebraic Reconstruction Technique

Numerical Evaluations for Multiplicative Algebraic Reconstru...

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Biomedical Imaging and Sensing Conference

作者： Aoyagi, Tomohiro Ohtsubo, Kouichi Toyo Univ Fac Informat Sci & Arts 2100 Kujirai Kawagoe Shi Saitama 3508585 Japan

ISBN: (数字)9781510647206

ISBN: (纸本)9781510647206;9781510647190

Image reconstruction can be formulated by the Fredholm equation of the first kind The method of projections onto convex sets (POCS) is an iterative algorithm for solving the equation. Multiplicative algebraic reconstruction techniques (MART) is one of POCS for solving a system of simultaneous equation. By discretizing the image reconstruction problem, we applied the MART to the problems and evaluate the image quality in computer simulations. We also investigated the normalized mean square error of reconstructed images with respect to the variations of the number of detectors and views, the relaxation parameters.

关键词： image reconstruction MART POCS iterative algorithm tomography

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PRIVACY-ACCURACY TRADE-OFF OF INFERENCE AS SERVICE

PRIVACY-ACCURACY TRADE-OFF OF INFERENCE AS SERVICE

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IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP)

作者： Jin, Yulu Lai, Lifeng Univ Calif Davis Dept ECE Davis CA 95616 USA

ISBN: (纸本)9781728176055

In this paper, we propose a general framework to provide a desirable trade-off between inference accuracy and privacy protection in the inference as service scenario. Instead of sending data directly to the server, the user will preprocess the data through a privacy-preserving mapping, which will increase privacy protection but reduce inference accuracy. To properly address the trade-off between privacy protection and inference accuracy, we formulate an optimization problem to find the optimal privacy-preserving mapping. Even though the problem is non-convex in general, we characterize nice structures of the problem and develop an iterative algorithm to find the desired privacy-preserving mapping.

关键词： statistical inference privacy-preserving privacy-accuracy trade-off iterative algorithm

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Source Localization using TDOA and FDOA Measurements with Sensor Information Uncertainties 40

Source Localization using TDOA and FDOA Measurements with Se...

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40th Chinese Control Conference (CCC)

作者： Qu, Xiaomei Liu, Tao Southwest Minzu Univ Key Lab Comp Syst State Ethn Affairs Commiss Chengdu 610041 Sichuan Peoples R China

ISBN: (纸本)9789881563804

This paper explores the source localization problem using the time difference of arrival (TDOA) and frequency difference of arrival (FDOA) measurements when sensor location information suffers from random uncertainties. The analysis of the Cramer-Rao lower bound (CRLB) illustrates that the sensor uncertainties can considerably deteriorate the localization accuracy, so we fully incorporate the sensor location information uncertainties into the problem formulation. An iterative source localization algorithm is proposed to recursively solve the formulated problem, where the sensor information uncertainties is incorporated in each iteration to improve the localization performance.

关键词： Source localization Sensor information uncertainties Cramer-Rao lower bound iterative algorithm

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