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The basic research of phase retrieval algorithm

OPTIK 2016年第4期127卷 1561-1566页

作者： Ma, Xinxue Wang, Jianli Chinese Acad Sci Changchun Inst Opt Fine Mech & Phys Changchun 130033 Cocos Keeling I Peoples R China

This paper introduces two algorithms of the phase retrieval, Gerchberg-Saxton algorithm and gradient search algorithm. We respectively get the function of the object of gradient search algorithm about the generalized pupil, wavefront and the zernike coefficients of the partial derivatives when double-frame images and their defocus as the input. The relationship between GS algorithm and the gradient search algorithm are revealed. This paper designs the simulation experiment with GS algorithm and gradient search algorithm when single-frame images and double-frame images are used as input. The experiment results show that the gradient search algorithm is superior to GS algorithm for a single-frame image as input. Both GS algorithm and gradient search algorithm can primely work out wavefront for double frame images of different defocus as the input, but the convergence rate of gradient search algorithm is evidently better than GS algorithm. (C) 2015 Elsevier GmbH. All rights reserved.

关键词： Phase retrieval GS algorithm gradient search algorithm Object-domain Fourier-domain

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Predictive feedback polarized dispersion control for PCF

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OPTICAL AND QUANTUM ELECTRONICS 2021年第9期53卷 1-22页

作者： Alwin, Tony St Thomas Inst Sci & Technol Dept Elect & Commun Kattaikonam PO Trivandrum 695584 Kerala India

Photonic crystal fibers, also known as microstructured or holey fibers generated great interest in the scientific community. Today, Index Guided photonic crystal fibers (PCFs) are established as an alternative fiber technology. Index Guided PCF addicted to challenges that reduce its durability and sensitivity of numerous PCF sensors according to their application field. Challenges may be in terms of polarization dispersion which arises due to Random imperfections that break the circular symmetry in PCF. To cope up with the above challenges, this work has proposed a Predictive Feedback Polarized Dispersion Control Model. Our model process with predictive feedback optimized error solution using Nonlinear Model Predictive Controller along with gradient search algorithm, which controls the polarization dispersion based on the Sequential Approach. A sequential approach is used here, to detect and separate the overlapped waves. Also, the Finite Element Analysis method has been accomplished to perform numerical analysis. Thus our model enhances the system performance in terms of Dispersion, Refractive Index, Confinement Loss, and Sensitivity.

关键词： Index guided PCF (IGPCF) Nonlinear model predictive controller (NMPC) gradient search algorithm Sequential approach Finite element method analysis (FEM)

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An Optimization-based Adaptive Sliding Mode Control for an Inverted Pendulum

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IETE JOURNAL OF REsearch 2024年第1期70卷 542-557页

作者： Pathak, Rajeev Ranjan Mohanty, Sidhanta Sengupta, Anindita Indian Inst Engn Sci & Technol Dept Elect Engn Howrah 711103 W Bengal India

The work proposes an optimization-based robust adaptive gain sliding mode control technique to handle bounded behavior of uncertainties/perturbations without having the exact knowledge of the bound a priori. The constant of the sliding surface follows dynamical adaptive nature using three optimization techniques, i.e. Harmony search algorithm, Bacterial Foraging Optimization algorithm and gradient search algorithm to extenuate the extent of chattering. The gain of the switching control law, which is a part of the sliding mode control design, is calculated using the gain adaption technique. Lyapunov Stability Criterion is applied to assure the stability of the closed-loop system with adaptable gain and the optimized value of the sliding constant. An inverted Pendulum system has been taken to validate the proposition both in the simulation environment and the hardware platform.

关键词： Adaptive sliding mode control Bacterial foraging optimization algorithm gradient search algorithm Harmony search algorithm Inverted pendulum Sliding mode control

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Application of genetic algorithm for computer-aided design and optimisation of microwave circuits

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IETE JOURNAL OF REsearch 2001年第3-4期47卷 141-144页

作者： Shukla, RK Biswas, A Indian Inst Technol Dept Elect Engn Kanpur 208016 Uttar Pradesh India

The application of genetic algorithm for computer-aided design and optimisation of microwave circuits Is presented using the example of three section Quarter wave transmission line transformers. The circuit chosen In this paper is a classic example to compare different optimisation algorithms[1]. Two different optimisation methods gradient search algorithm and genetic algorithm have been used for the optimisation. It has been found that the optimisation method based on genetic algorithm is very robust for the optimisation of microwave circuits.

关键词： optimisation genetic algorithm gradient search algorithm quarter wave transmission line transformer

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Femur Bone Volumetric Estimation for Osteoporosis Classification Using Optimization-Based Deep Belief Network in X-Ray Images

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COMPUTER JOURNAL 2019年第11期62卷 1656-1670页

作者： Shankar, N. Sathish Babu, S. Viswanathan, C. Saveetha Engn Coll Dept Biomed Engn Chennai 602105 Tamil Nadu India Annamalai Univ Dept Elect & Instrumentat Engn Chidambaram 608002 Tamil Nadu India GRT Inst Engn & Technol Dept Elect & Commun Engn Tiruttani 631209 Tamil Nadu India

Osteoporosis classification is a significant requirement in the medical field to automatically classify the patients with skeleton disorder that occurs as a result of aging. The classification algorithms required improved accuracy and computationally less complexity. Accordingly, this paper proposes a classification method using the proposed gradient harmony search (GHS) optimization-based deep belief network. The GHS is developed by integrating the harmony search (HS) in the gradient descent (GD) algorithm. The osteoporosis classification is progressed as five major steps: preprocessing, segmentation using active shape model, geometric estimation using the proposed template search method, feature extraction for extracting the medical and image level features, and osteoporosis classification using the proposed GHS based deep belief network. The proposed template search method updates the geometric points of the femur segment effectively and automatically. Experimentation using the real-time database ensures the effectiveness of the proposed method in terms of accuracy, sensitivity, and specificity. The proposed method acquired the accuracy of 0.9539, proving that the osteoporosis classification using the proposed algorithm seems to be effective in taking accurate decisions regarding the patients.

关键词： femur bone osteoporosis classification deep belief network harmony search algorithm gradient search algorithm

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Automatic filter design for 3-D sound movement in embedded applications

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ACOUSTICAL SCIENCE AND TECHNOLOGY 2007年第4期28卷 219-229页

作者： Tsujino, Kosuke Kobayashi, Wataru Onoye, Takao Nakamura, Yukihiro Kyoto Univ Dept Commun & Comp Engn Kyoto Japan Arnis Sound Technol Co Ltd Tokyo Japan Osaka Univ Dept Informat Syst Engn Suita Osaka Japan

In this paper, we propose an automatic method of designing digital filters for three-dimensional (3-D) sound movement that is dedicated to embedded applications. By this method, read-only memory (ROM) capacity and computational load are reduced with only slight degradation of the 3-D sound effect. For practical applications of 3-D sound, the continuous movement of a virtual sound image is indispensable. To achieve 3-D sound movement, the interpolation of filter coefficients is often required;however, the frequency response of an intermediate filter obtained by interpolation is severely distorted using conventional automatic design methods. The proposed method reduces this distortion by evaluating the response of the intermediate filters in the optimization process. The results of objective evaluation and subjective listening tests show that the proposed method improves the perceptual quality of 3-D sound movement, even with runtime interpolation of filter coefficients.

关键词： 3-D sound Head-related transfer function Interpolation gradient search algorithm

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An iterative Maximum-Likelihood based parameter estimation algorithm for Nakagami-m distribution

An iterative Maximum-Likelihood based parameter estimation a...

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Conference on Wireless Sensing and Processing III

作者： Dianat, Sohail Rao, Raghuveer Rochester Inst Technol Dept Elect Engn New York NY 14623 USA

ISBN: (纸本)9780819471710

Estimation of channel fading parameters is an important task in the design of communication links such as in maximum ratio combining (MRC), where the SNR of the link has to be estimated. The maximum combining weights are directly related to the SNR or the fading channel coefficients. In this paper, we propose iterative techniques based on Maximum Likelihood parameter estimation to estimate the parameters of Nakagami-m distribution in the presence of additive white Gaussian noise. We show that the proposed iterative algorithms converge to a unique solution independent of the initial condition. However, for the purpose of fast convergence, a method is used to find an initial condition close to the true solution. This initial condition is obtained by solving for the unique positive root of a polynomial. Comparisons of our proposed approaches are made with respect to the noise and initial conditions. The performance of the algorithm with respect to the Cramer-Rao bound (CRB) is investigated. Computer simulation results for different signal to noise ratios (SNR) are presented.

关键词： estimation Nakagami-m distribution Maximum Likelihood Cramer-Rao bound (CRB) gradient search algorithm variance contraction mapping

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Phase Retrieval Hybrid algorithm for Optical Surface testing of the high dynamic range error 7

Phase Retrieval Hybrid Algorithm for Optical Surface testing...

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7th International Symposium on Advanced Optical Manufacturing and Testing Technologies (AOMATT) - Optical Test and Measurement Technology and Equipment

作者： Feng Liang Zeng Zhi-ge Wu Yong-qian Chinese Acad Sci Inst Opt & Elect Chengdu 610209 Peoples R China Univ Chinese Acad Sci Beijing 100049 Peoples R China

ISBN: (纸本)9781628413571

The phase retrieval hybrid algorithm based on gradient search algorithm and GS algorithm is designed for surface testing of the high dynamic range error beyond one wavelength after the rough polish process. Phase retrieval is a wave front sensing method that uses the intensity distribution to reconstruct the phase distribution of optical field. In the rough polish process of optical surface testing, there is the problem of phase wrapping caused by the high dynamic range error, which makes it hard to be measured by interferometers. In this condition, infrared interferometers are widely used for optical testing, but the operation of infrared interferometer is complicated because of the invisibility of infrared light and it's very sensitive to the temperature, vibration and turbulence. The phase retrieval hybrid algorithm derives from gradient search algorithm and GS algorithm, aiming to solve the problem of phase wrapping caused by the high dynamic range error. Firstly, phase distribution is described by Zernike polynomials and the coefficients of Zernike polynomials are optimized by the gradient search algorithm to retrieve the low frequency error beyond one wavelength. Then GS algorithm is used to retrieve the high frequency error of small value. In the simulated calculation, the hybrid algorithm is used for surface testing of a spherical mirror with PV 2.42 lambda, RMS 0.41 lambda. The retrieved surface is PV 2.53 lambda, RMS 0.42 lambda. The simulation result shows that the hybrid algorithm is effective and accurate for optical surface testing of high dynamic range error.

关键词： optical surface testing Phase retrieval gradient search algorithm GS algorithm High dynamic range error

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Rate Maximization in Coupled MIMO Systems: A Generic algorithm For Designing Single-Port Matching Networks

Rate Maximization in Coupled MIMO Systems: A Generic Algorit...

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IEEE Wireless Communications and Networking Conference (WCNC)

作者： Hassan, Yahia Wittneben, Armin Swiss Fed Inst Technol Commun Technol Lab CH-8092 Zurich Switzerland

ISBN: (纸本)9781479930838

Compact arrays are known to be associated with antenna coupling and noise correlation. The noise can be either antenna noise, LNA noise or downstream noise. Due to these effects, it was shown that the matching network affects the performance of MIMO systems with coupled receiver antennas. Since the optimal multiport matching network is of very high complexity as well as very narrow operation bandwidth, development of single-port (SP) matching networks that boost the performance became inevitable. In this paper we develop a gradient-search algorithm to design the matching network for achievable rate maximization of multi user MIMO systems. For arty combination of noise sources, we rigorously derive the exact gradient of the achievable rate with respect to the components of the matching network. We assume either full knowledge of the spatial channel or knowing its statistical properties. In the later case we optimize the matching network to maximize the Jensen's bound. Substantial performance enhancement is shown when our algorithms are used. Significant reduction in the array area is gained in comparison to the often used lambda/2 antenna spacing without taking coupling into account. This can be vital for future wireless systems adopting massive MIMO arrays. Via eigenvalues distribution simulations at different SNR regimes, we show an intuitive link to the communication theory.

关键词： MIMO communication antenna arrays gradient methods MIMO systems antenna coupling coupled receiver antenna eigenvalues distribution simulations generic algorithm gradient search algorithm massive MIMO array matching network design multiuser MIMO system noise correlation noise sources optimal multiport matching network single port matching networks Antenna arrays MIMO Noise Receiving antennas Symmetric matrices

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