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Designing PAR-constrained periodiciaperiodic sequence via the gradient-based method

SIGNAL PROCESSING 2018年 147卷 11-22页

作者： Tang, Liang Zhu, Yongfeng Fu, Qiang Natl Univ Def Technol Changsha 410073 HN Peoples R China

Periodiciaperiodic sequence with good correlation and stopband properties has received widespread attention and been widely applied in radar and communication systems. To meet the hardware requirement and maximize the transmitter efficiency, the unimodular or peak-to-average ratio (PAR) constraint is always required in sequence design. In this paper, we consider the problem of designing PAR-constrained periodic/aperiodic sequence with good properties. After establishing the corresponding criterions for both correlation and stopband properties, the unified PAR-constrained problem is formulated and then transformed into an unconstrained minimization problem via sequence synthesis. To solve the problem, an efficient gradient-based algorithm is proposed to minimize the objective function directly. As the main steps can be implemented by fast Fourier transform (FFT) operations and Hadamard product, the whole algorithm is computationally efficient. In addition, the proposed algorithm can be applied to design both the periodic and aperiodic sequences by choosing proper parameters. Numerical experiments show that the proposed algorithm has better performance than the state-of-the-art algorithms in terms of the sequence quality and the running time. (C) 2018 Elsevier B.V. All rights reserved.

关键词： Autocorrelation Stopband property Sequence synthesis gradient-based method PAR constraint Periodic/aperiodic sequence design

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Parameter identification for on-line model updating in hybrid simulations using a gradient-based method

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EARTHQUAKE ENGINEERING & STRUCTURAL DYNAMICS 2018年第2期47卷 269-293页

作者： Chuang, Ming-Chieh Hsieh, Shang-Hsien Tsai, Keh-Chyuan Li, Chao-Hsien Wang, Kung-Juin Wu, An-Chien Natl Ctr Res Earthquake Engn Taipei Taiwan Natl Taiwan Univ Dept Civil Engn Taipei Taiwan

To improve the efficiency of model fitting, parameter identification techniques have been actively investigated. Recently, the applications of parameter identification migrated from off-line model fitting to on-line model updating. The objective of this study is to develop a gradient-based method for model updating to advance hybrid simulation also called hybrid test. A novel modification of the proposed method, which can reduce the number of design variables to improve the identification efficiency, is illustrated in detail. To investigate the model updating, simulated hybrid tests were conducted with a 5-story steel frame equipped with buckling-restrained braces (BRBs) utilized in the shaking table tests conducted in E-Defense in Japan in 2009. The calibrated analytical model that was verified with the test results can serve as the reference model. In the simulated hybrid tests, the physical BRB substructure is numerically simulated by utilizing a truss element with the 2-surface model identical to the part of the reference model. Such numerical verification allows simulation of measurement errors for investigation on the performance of the proposed method. Moreover, the feasibility of sharing the identified parameter values, which were obtained from the physical substructure responses, with the relevant numerical models is also verified with the artificial component responses derived from the physical experiments.

关键词： buckling-restrained brace gradient-based method hybrid simulation model updating optimization parameter identification

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Debris flow velocity estimation: A comparison between gradient-based method and cross-correlation method

Debris flow velocity estimation: A comparison between gradie...

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Conference on Image Processing - Algorithms and Systems

作者： Uddin, MS Inaba, H Yoshida, Y Itakura, Y Kyoto Inst Technol Dept Elect & Informat Sci Sakyo Ku Kyoto 6068585 Japan

ISBN: (纸本)0819444073

Debris flow causes lot of damages all over the world. The surface velocity of such a natural random flow is one of the important physical parameters that are considered in drawing a hazard map or constructing a sediment control dam. gradient-based method along with a multiscale smoothing operation finds application in the two-dimensional velocity estimation of a debris flow from its video images. This paper investigates the performance of another optical flow determination technique - the cross-correlation method in the above application and compares the results with those obtained by the gradient-based method. A computer simulation with synthetic random moving images shows that the accuracy of the cross correlation method is higher than that of the gradient-based method.

关键词： debris flow spatial filtering optical flow estimation gradient-based method cross-correlation method

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The Sub-pixel Searching Algorithm based on gradient in Digital Speckle Correlation method

The Sub-pixel Searching Algorithm based on Gradient in Digit...

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International Conference on Mechatronic Sciences, Electric Engineering and Computer (MEC)

作者： Wang, Linlin Tang, Chen Shenyang Aerosp Univ Engn Training Ctr Shenyang Peoples R China Tianjin Univ Dept Appl Phys Coll Sci Tianjin 300072 Peoples R China

ISBN: (纸本)9781479925650

Digital speckle correlation method (DSCM) is an successful nondestructive testing technique for the whole displacements. The computational accuracy is a challenging issue. In this paper, a new gradient-based method is proposed, the accuracy of the method is demonstrated via three computed-simulated speckle image pairs. Combining the method with radial basis function interpolation, two experimentally obtained deformation fields are measured.

关键词： Digital speckle correlation method (DSCM) computational accuracy gradient-based method radial basis function

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Adaptive centre-frequency bandpass state-space digital filters and their l2-sensitivity analysis

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SICE JOURNAL OF CONTROL MEASUREMENT AND SYSTEM INTEGRATION 2025年第1期18卷

作者： Hinamoto, Yoichi Doi, Akimitsu Natl Inst Technol Kagawa Coll Dept Elect & Comp Engn Takamatsu Japan Hiroshima Inst Technol Dept Comp Sci 2-1-1 MiyakeSaeki Ku Hiroshima 7315193 Japan

This paper explores an adaptive centre-frequency bandpass state-space digital filter by expanding a sign algorithm into the gradient-based method. To this end, a simple method for deriving a bandpass state-space digital filter with tuneable centre-frequency from a prototype low-pass filter and low-pass/bandpass transformation is presented. An adaptive iterative algorithm is then developed by expanding a sign algorithm into the gradient-based method. Also, l(2)-sensitivities for the bandpass state-space digital filter with tuneable centre-frequency are analysed where an l(2)-sensitivity measure for evaluating the whole l(2)-sensitivities is deduced. Numerical experiments are included to demonstrate the validity and effectiveness of the adaptive centre-frequency bandpass state-space digital filter and the l(2)-sensitivity analysis.

关键词： Adaptive centre-frequency bandpass digital filter gradient-based method l(2)-sensitivity analysis sign algorithm state-space approach

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SA-ISAR imaging algorithm based on the gradient signal recovery method

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JOURNAL OF ENGINEERING-JOE 2019年第20期2019卷 6577-6581页

作者： Ji, Bingren Zhao, Bin Wang, Yong Xu, Rongqing Harbin Inst Technol Res Inst Elect Engn Technol Dept Informat & Commun Engn Harbin 150001 Heilongjiang Peoples R China

As the radar system tends to be complex, obtaining well-focused images with discontinued apertures becomes a challenge. Here, a new sparse aperture inverse synthetic aperture radar (SA-ISAR) imaging approach through the signal recovery method is proposed. Considering the available samples of data sets as fixed values and the missing samples as variables, the algorithm employs a gradient-based method to approach the true values of missing samples by iterations. The algorithm can recover the complete signals with a high precision. Experiments based on the measured data are carried out to validate the superiority of the novel algorithm.

关键词： synthetic aperture radar radar imaging iterative methods complete signals SA-ISAR imaging algorithm gradient signal recovery method radar system discontinued apertures sparse aperture inverse synthetic aperture radar imaging approach available samples missing samples gradient-based method

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On the determination of material parameters for internal variable thermoelastic-viscoplastic constitutive models

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INTERNATIONAL JOURNAL OF PLASTICITY 2007年第8期23卷 1349-1379页

作者： Andrade-Campos, A. Thuillier, S. Pilvin, P. Teixeira-Dias, F. Univ Aveiro Dept Engn Mecan P-3810193 Aveiro Portugal Univ Bretagne Sud Lab Genie Mecan & Mat LG2M F-56231 Lorient France

The work presented in this paper deals with the determination of material parameters used in internal variable constitutive models. In order to determine the best suited material parameter set, in the less computationally expensive way, two optimization approaches are used: (i) a gradient-based method and (ii) a continuous evolutionary algorithm (EA) method. The first approach uses a combination of the steepest descent gradient and the Levenberg-Marquardt techniques. The performance of this method is known to be highly dependent on the starting et of parameters and its results are often inconsistent. The EA-based technique provides a better way to determine an optimized set of parameters (the overall minimum). Thus, the difficulty of choosing a starting set of parameters for this process is minor. The main application in this work is a 16 parameter thermoelastic-viscoplastic constitutive model. Experimental data was obtained from tensile and shear tests at different temperatures and used to compare with numerical results and to determine the correct set of material parameters. Numerical constraints were introduced to enforce physical requirements on the material parameters. Both methods are used to determine the 12 material parameters needed for an AA1050-O aluminium alloy. Although the EA-based method achieved a slightly better result, it proved to be computationally more expensive than the gradient-based method. (c) 2006 Elsevier Ltd. All rights reserved.

关键词： parameter identification thermoelastic viscoplastic constitutive model optimization gradient-based method evolutionary algorithm

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methodology to analyse carbon fibre/epoxy composite pressure vessel based on finite element modelling and classical laminated theory

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JOURNAL OF THE BRAZILIAN SOCIETY OF MECHANICAL SCIENCES AND ENGINEERING 2023年第6期45卷 1-9页

作者： Iwasaki, Kelvin Masakazu Kuroki Reis, Pedro Almeida Oliveira, Luiz Gabriel Rauber, Willian Kevin De Medeiros, Ricardo Santa Catarina State Univ Dept Mech Engn UDESC Rua Paulo Malschitzki 200 BR-89219710 Joinville SC Brazil

Cylindrical pressure vessels are commonly used for storing gaseous fuels on-board, but they have several disadvantages. The domed heads of these vessels are frequently over-designed, and their manufacture poses challenges. In this study, a novel approach is presented to optimize the design of a composite pressure vessel that achieves maximum strength while minimizing thickness. The composite vessel used in the study has a thin-walled elliptical head with a 2:1 axis ratio. To determine the optimal design, the researchers employ the gradient method, which involves extracting membrane forces from a critical section of the finite element (FE) model. They then use in-house classical laminated theory (CLT) software, which incorporates the Tsai-Wu failure criterion and keeps the thickness of each ply constant, to update the stacking sequence and meet the design constraints. The thickness and orientation of each ply are ensured to satisfy the safety factor established by the ASME standard for a specific class of pressure vessels. The number of layers in the optimal stacking sequence was reduced by three layers compared to the initial stacking sequence. Using this approach, the researchers were able to reduce the number of layers required while finding the optimal stacking sequence for the initial composite pressure vessel. This methodology can be applied to enhance the design of composite pressure vessels and aid in their development.

关键词： Composite pressure vessel gradient-based method Finite element analysis Classical laminated theory Failure modes

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Compressive sensing for noisy solder joint imagery based on convex optimization

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SOLDERING & SURFACE MOUNT TECHNOLOGY 2016年第2期28卷 114-122页

作者： Zhao, Huihuang Chen, Jianzhen Xu, Shibiao Wang, Ying Qiao, Zhijun HengYang Normal Univ Dept Comp Sci Hengyang Peoples R China Chinese Acad Sci Natl Lab Pattern Recognit Inst Automat Beijing Peoples R China Univ Texas Pan Amer Dept Math Edinburg TX 78541 USA

Purpose - The purpose of this paper is to develop a compressive sensing (CS) algorithm for noisy solder joint imagery compression and recovery. A fast gradient-based compressive sensing (FGbCS) approach is proposed based on the convex optimization. The proposed algorithm is able to improve performance in terms of peak signal noise ratio (PSNR) and computational cost. Design/methodology/approach - Unlike traditional CS methods, the authors first transformed a noise solder joint image to a sparse signal by a discrete cosine transform (DCT), so that the reconstruction of noisy solder joint imagery is changed to a convex optimization problem. Then, a so-called gradient- based method is utilized for solving the problem. To improve the method efficiency, the authors assume the problem to be convex with the Lipschitz gradient through the replacement of an iteration parameter by the Lipschitz constant. Moreover, a FGbCS algorithm is proposed to recover the noisy solder joint imagery under different parameters. Findings - Experiments reveal that the proposed algorithm can achieve better results on PNSR with fewer computational costs than classical algorithms like Orthogonal Matching Pursuit (OMP), Greedy Basis Pursuit (GBP), Subspace Pursuit (SP), Compressive Sampling Matching Pursuit (CoSaMP) and Iterative Re-weighted Least Squares (IRLS). Convergence of the proposed algorithm is with a faster rate O(k*k) instead of O(1/k). Practical implications - This paper provides a novel methodology for the CS of noisy solder joint imagery, and the proposed algorithm can also be used in other imagery compression and recovery. Originality/value - According to the CS theory, a sparse or compressible signal can be represented by a fewer number of bases than those required by the Nyquist theorem. The new development might provide some fundamental guidelines for noisy imagery compression and recovering.

关键词： Noisy solder joint imagery Compressive sensing (CS) Convex optimization gradient-based method Orthogonal matching pursuit Greedy basis pursuit Subspace pursuit and compressive sampling matching pursuit Iterative re-weighted least squares

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gradient-based optimizer: A new metaheuristic optimization algorithm

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INFORMATION SCIENCES 2020年 540卷 131-159页

作者： Ahmadianfar, Iman Bozorg-Haddad, Omid Chu, Xuefeng Behbahan Khatam Alanbia Univ Technol Dept Civil Engn Behbahan Iran Univ Tehran Coll Agr & Nat Resources Fac Agr Engn & Technol Dept Irrigat & Reclamat Engn Tehran Iran North Dakota State Univ Dept Civil & Environm Engn Dept 2470 Fargo ND USA

In this study, a novel metaheuristic optimization algorithm, gradient-based optimizer (GBO) is proposed. The GBO, inspired by the gradient-based Newton's method, uses two main operators: gradient search rule (GSR) and local escaping operator (LEO) and a set of vectors to explore the search space. The GSR employs the gradient-based method to enhance the exploration tendency and accelerate the convergence rate to achieve better positions in the search space. The LEO enables the proposed GBO to escape from local optima. The performance of the new algorithm was evaluated in two phases. 28 mathematical test functions were first used to evaluate various characteristics of the GBO, and then six engineering problems were optimized by the GBO. In the first phase, the GBO was compared with five existing optimization algorithms, indicating that the GBO yielded very promising results due to its enhanced capabilities of exploration, exploitation, convergence, and effective avoidance of local optima. The second phase also demonstrated the superior performance of the GBO in solving complex real-world engineering problems. Source codes of the GBO algorithm are publicly available at http://***/codes/. (c) 2020 Elsevier Inc. All rights reserved.

关键词： Optimization gradient-based method Metaheuristic algorithm Constrained optimization problem

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