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Performance comparison between optimization algorithms for asymmetrical cascaded multilevel inverter control

AUTOMATIKA 2020年第4期61卷 626-642页

作者： Manai, Lazhar Armi, Faouzi Besbes, Mongi Univ Tunis Natl Engn Sch Tunis Lab Robot Informat & Complex Syst BP 37 Tunis 1002 Tunisia Univ Carthage Higher Inst Informat & Commun Technol BP 123 Carthage 1164 Hammam Chatt Tunisia

This paper discusses the hardware and control system design of the asymmetric cascade multilevel inverter. The asymmetric cascaded multilevel inverter structure is adopted to minimize bridges, gate drive circuits and DC power source number. Therefore, the proposed structure is able to generate higher voltage at higher speed with low switching losses and high efficiency. Selective Harmonic Elimination (SHE) based on newton-raphson (N-R) algorithm is developed to calculate a switching angle for a range of modulation index to control asymmetric cascade multilevel inverter. Simulation results prove that newton-raphson technique is more effective than genetic algorithm (G-A) and equal calculated switching angles method (ECSA). A comparison between the algorithm performance for 9-level asymmetric cascade H-bridge inverter control was evaluated and experimentally tested on FPGA-based prototypes

关键词： Asymmetrical CHB multilevel inverter newton-raphson algorithm genetic algorithm switching angles THD FPGA

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Consistent Tangent Stiffness of a Three-Dimensional Wheel-Rail Interaction Element

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INTERNATIONAL JOURNAL OF STRUCTURAL STABILITY AND DYNAMICS 2021年第14期21卷

作者： Gu, Quan Pan, Jinghao Liu, Yongdou Xiamen Univ Sch Architecture & Civil Engn Xiamen 361005 Peoples R China Qinghai Univ Sch Civil Engn Xining 810016 Peoples R China

Consistent tangent stiffness plays a crucial role in delivering a quadratic rate of convergence when using newton's method in solving nonlinear equations of motion. In this paper, consistent tangent stiffness is derived for a three-dimensional (3D) wheel-rail interaction element (WRI element for short) originally developed by the authors and co-workers. The algorithm has been implemented in finite element (FE) software framework (OpenSees in this paper) and proven to be effective. Application examples of wheelset and light rail vehicle are provided to validate the consistent tangent stiffness. The quadratic convergence rate is verified. The speeds of calculation are compared between the use of consistent tangent stiffness and the tangent by perturbation method. The results demonstrate the improved computational efficiency of WRI element when consistent tangent stiffness is used.

关键词： Consistent tangent stiffness wheel-rail interaction vehicle-track systems quadratic convergence rate newton-raphson algorithm finite element method

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New method of compensation the out-of-focus defect introduced by the optical system of a micro-camera

New method of compensation the out-of-focus defect introduce...

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8th International Conference on Wireless Networks and Mobile Communications (WINCOM)

作者： Ghennioui, Hicham El Kamili, Mohamed Univ Sidi Mohammed Ben Abdellah Fac Sci & Technol Syst & Components Lab Fes Morocco Hassan II Univ Casablanca Higher Sch Technol Signals Syst & Components Lab Casablanca Morocco

ISBN: (纸本)9781728190150

This work addresses the problem of the out-offocus defect introduced by the optical system of a micro-camera. We present a new image deblurring technique: it combines a new out-of-focus blur estimation with the modified Wiener filter. The proposed technique consists then of two steps. The first one allows to estimate the point-spread-function of the optical system by the iterative newton-raphson algorithm, however the second one consists to recover the image by the modified Wiener filter: the classical Wiener filter is adjusted by using the proposed blur measurement metric. The main advantage of the proposed technique is that it's no-reference (the blur measurement doesn't need the original image as reference and the deblurring image algorithm is blind). Computer simulations are provided in order to illustrate the effectiveness of the proposed approach. A comparison with a classical Wiener filter is also performed, emphasizing the good behavior of the proposed method.

关键词： Blind deblurring algorithms Point Spread Function Wiener filter newton-raphson algorithm Blur measurement

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Fitting competing risks data to bivariate Pareto models

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COMMUNICATIONS IN STATISTICS-THEORY AND METHODS 2019年第5期48卷 1193-1220页

作者： Shih, Jia-Han Lee, Wei Sun, Li-Hsien Emura, Takeshi Natl Cent Univ Grad Inst Stat 300 Zhongda Rd Taoyuan 32001 Taiwan

This paper revisits two bivariate Pareto models for fitting competing risks data. The first model is the Frank copula model, and the second one is a bivariate Pareto model introduced by Sankaran and Nair (1993). We discuss the identifiability issues of these models and develop the maximum likelihood estimation procedures including their computational algorithms and model-diagnostic procedures. Simulations are conducted to examine the performance of the maximum likelihood estimation. Real data are analyzed for illustration.

关键词： Bivariate Pareto distribution Frank copula Kendall's tau newton-raphson algorithm Survival analysis

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Weighted estimation for multivariate shared frailty models for complex surveys

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LIFETIME DATA ANALYSIS 2019年第3期25卷 469-479页

作者： Wang, Jing Univ Texas Arlington Arlington TX 76019 USA

Multivariate frailty models have been used for clustered survival data to characterize the relationship between the hazard of correlated failures/events and exposure variables and covariates. However, these models can introduce serious biases of the estimation for failures from complex surveys that may depend on the sampling design (informative or noninformative). In order to consistently estimate parameters, this paper considers weighting the multivariate frailty model by the inverse of the probability of selection at each stage of sampling. This follows the principle of the pseudolikelihood approach. The estimation is carried out by maximizing the penalized partial and marginal pseudolikelihood functions. The performance of the proposed estimator is assessed through a Monte Carlo simulation study and the 4 waves of data from the 1998-1999 Early Childhood Longitudinal Study. Results show that the weighted estimator is consistent and approximately unbiased.

关键词： Multivariate frailty model Sampling weight newton-raphson algorithm Pseudolikelihood

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Logistic regression analysis of non-randomized response data collected by the parallel model in sensitive surveys

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AUSTRALIAN & NEW ZEALAND JOURNAL OF STATISTICS 2019年第2期61卷 134-151页

作者： Tian, Guo-Liang Liu, Yin Tang, Man-Lai Southern Univ Sci & Technol Shenzhen Peoples R China Zhongnan Univ Econ & Law Sch Math & Stat Wuhan 430073 Hubei Peoples R China Hang Seng Univ Hong Kong Hong Kong Peoples R China

To study the relationship between a sensitive binary response variable and a set of non-sensitive covariates, this paper develops a hidden logistic regression to analyse non-randomized response data collected via the parallel model originally proposed by Tian (2014). This is the first paper to employ the logistic regression analysis in the field of non-randomized response techniques. Both the newton-raphson algorithm and a monotone quadratic lower bound algorithm are developed to derive the maximum likelihood estimates of the parameters of interest. In particular, the proposed logistic parallel model can be used to study the association between a sensitive binary variable and another non-sensitive binary variable via the measure of odds ratio. Simulations are performed and a study on people's sexual practice data in the United States is used to illustrate the proposed methods.

关键词： hidden logit model newton-raphson algorithm non-randomized parallel model odds ratio quadratic lower bound algorithm

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On computing maximum likelihood estimates for the negative binomial distribution

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STATISTICS & PROBABILITY LETTERS 2019年 148卷 54-58页

作者： Bandara, Udika Gill, Ryan Mitra, Riten Univ Louisville Dept Math Louisville KY 40292 USA Univ Louisville Dept Bioinformat & Biostat Louisville KY 40202 USA

This paper proves that starting value for the newton-raphson method can be chosen so that the method is guaranteed to find the maximum likelihood estimate of the parameters of a negative binomial distribution when it ... 详细信息

关键词： Negative binomial distribution newton-raphson algorithm Fixed point Maximum likelihood estimation

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Bio-inspired propulsion of micro-swimmers within a passive cervix filled with couple stress mucus

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COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2020年 189卷 105313-105313页

作者： Asghar, Zeeshan Ali, Nasir Javid, Khurram Waqas, Muhammad Dogonchi, Abdul Sattar Khan, Waqar Azeem Natl Univ Technol NUTECH Sch Appl Sci & Humanities Islamabad 44000 Pakistan Int Islamic Univ Dept Math & Stat Islamabad 44000 Pakistan Northern Univ Dept Math Nowshera 24100 Kpk Pakistan Islamic Azad Univ Dept Mech Engn Aliabad Katoul Branch Aliabad Katoul Iran Beijing Inst Technol Sch Math & Stat Beijing 100081 Peoples R China

Background and objective: The swimming mechanism of self-propelling organisms has been imitated by biomedical engineers to design the mechanical micro bots. The interaction of these swimmers with surrounding environment is another important aspect. The present swimming problem integrates Taylor sheet model with couple stress fluid model. The thin passage containing micro-swimmers and mucus is approximated as a rigid (passive) two-dimensional channel. The spermatozoa forms a pack quite similar as a complex wavy sheet. Methods: Swimming problem with couple stress cervical liquid (at low Reynolds number) leads to a linear sixth order differential equation. The boundary value problem (BVP) is solved analytically with two unknowns i.e. speed of complex wavy sheet and flow rate of couple stress mucus. After utilizing this solution into equilibrium conditions these unknowns can be computed via newton-raphson algorithm. Furthermore, the pairs of numerically calculated organism speed and flow rate are utilized in the expression of power dissipation. Results: This work describes that the speed of micro-swimmers can be enhanced by suitable rheology of the surrounding liquid. The usage of couple stress fluid as compared to newtonian fluid enhances the energy dissipation and reduces the flow rate. On the other hand complex wavy surface also aids the organisms to swim faster. (C) 2020 Elsevier B.V. All rights reserved.

关键词： Complex wavy sheet Couple stress fluid Low Reynolds number newton-raphson algorithm

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A Novel newton-raphson-Based Searching Method for the MTPA Control of PMaSynRM Considering Magnetic and Cross Saturation 23

A Novel Newton-Raphson-Based Searching Method for the MTPA C...

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13th International Conference on Electrical Machines (ICEM)

作者： Wang, Shuo Degano, Michele Kang, Jinsong Galassini, Alessandro Gerada, Chris Tongji Univ Coll Elect & Informat Engn Shanghai Peoples R China Univ Nottingham Power Elect Machines & Control Grp Nottingham England Univ Nottingham Ningbo China PEMC Grp Ningbo Peoples R China

ISBN: (纸本)9781538624777

Maximum torque per ampere control (MTPA) takes full advantage of the reluctance torque aiming at the minimum copper loss, which can increase the torque output under the minimum current conditions. The traditional MTPA method makes use of equations with constant inductance values which are implemented as look-up tables. However, the inductances of the motor present both magnetic saturation and cross-saturation characteristics. Those parameters are changing depending on the operating point. This paper presents a novel MTPA control strategy of permanent-magnet assisted synchronous reluctance motor (PMaSynRM) implementing a newton-raphson-Based Searching Method for improving the control accuracy for optimal current reference. The proposed method eliminates the need of fitting operations due to the nonlinearity of the MTPA formulation and takes the inductance variation, due to magnetic saturation, into account. Finally, the effectiveness of the proposed method is verified by means of Matlab/Simulink simulations.

关键词： PM assisted Reluctance Motor MTPA control newton-raphson algorithm Magnetic Saturation Cross Saturation

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A numerical method for forward kinematics of general Stewart manipulator using natural coordinates

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JOURNAL OF ADVANCED MECHANICAL DESIGN SYSTEMS AND MANUFACTURING 2019年第1期13卷

作者： Wang, Ruobing Wu, Hongtao Liu, Yanli Yang, Xiaolong Zhang, Xuexiang Nanjing Univ Aeronaut & Astronaut Coll Mech & Elect Engn 29 Yudao St Nanjing 210016 Jiangsu Peoples R China Jiangsu Coll Safety Technol Dept Mech Engn 1 Univ Rd Xuzhou 221011 Jiangsu Peoples R China

In this paper, a numerical method for forward kinematics of general Stewart manipulator using natural coordinates is presented. The kinematic equations are in quadratic foul's and the corresponding Jacobian matrix is a linear function of coordinates because of using natural coordinates. According to the characteristics of the kinematic equations, the newton-raphson algorithm is simplified to decrease the renewal time of iterations between equations and Jacobian matrix, and used to solve the kinematic equations. The singularity and convergence problems of the algorithm are discussed. Furthermore, the method using natural coordinates is compared with the traditional method using rotation matrix through numerical examples. Comparison results show that the method using natural coordinates is very accurate, more efficient, and has a greater convergence domain.

关键词： Natural coordinates Forward kinematics Stewart manipulator newton-raphson algorithm Numerical method

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