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General A-P Iterative Algorithm in Shift-invariant Spaces

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Acta Mathematica Sinica,English Series 2009年第4期25卷 545-552页

作者： jun xian Song LI Department of Mathematics Sun Yat-sen ( Zhongshan) University Guangzhou 510275 P. R. China Department of Mathematics Zhejiang University Hangzhou 310027 P. R. China

A general A-P iterative algorithm in a shift-invariant space is presented. We use the algorithm to show reconstruction of signals from weighted samples and also show that the general improved algorithm has better conv... 详细信息

关键词： irregular sampling iterative algorithm lattice-invariant space shift-invariant space spline subspace

Improved Sampling and Reconstruction in Spline Subspaces

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Acta Mathematicae Applicatae Sinica 2016年第2期32卷 447-460页

作者： jun xian Song LI Department of Mathematics and Guangdong Province Key Laboratory of Computational Science Sun Yat-sen University Department of Mathematics Zhejiang University

As a special shift-invariant spaces, spline subspaces yield many advantages so that there are many practical applications for signal or image processing. In this paper, we pay attention to the sampling and reconstruction problem in spline subspaces. We improve lower bound of sampling set conditions in spline subspaces. Based on the improved explicit lower bound, a improved explicit convergence ratio of reconstruction algorithm is obtained. The improved convergence ratio occupies faster convergence rate than old one. At the end, some numerical examples are shown to validate our results.

关键词： irregular sampling iterative algorithm error estimate spline subspace

Theoretical Study on the Structures and Electronic Spectra of the Derivatives of C_(60)-P-2,4,6-Triphenyl Borazinc

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Chinese Journal of Structural Chemistry 2005年第10期24卷 1140-1144页

作者： JIANG qi-jun Department of Chemistry Xiaogan University Xiaogan 432000 China

The structures and electronic spectra of the derivatives of C60-P-2,4,6-triphenyl borazinc have been studied by using AM 1 method. The calculated results indicate that this kind of compounds has a lower energy difference between HOMO and LUMO. It is found that the electron cloud on unoccupied frontier orbital mainly comes from the contribution of C60, while that on occupied frontier orbital mainly concentrates on the side chain. A long-lived charge-separated state may occur in the objective compounds.

关键词： derivatives of C60-P-2,4,6-triphenyl borazinc electronic spectra charge-separated state AM1

N-soliton solutions for the nonlocal two-wave interaction system via the Riemann–Hilbert method

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Chinese Physics B 2018年第12期27卷 157-163页

作者： Si-qi Xu xian-Guo Geng School of Mathematics and Statistics Zhengzhou UniversityZhengzhou 450001China College of Civil Engineering Xinyang Normal UniversityXinyang 464000China

In this paper, a nonlocal two-wave interaction system from the Manakov hierarchy is investigated via the Riemann–Hilbert approach. Based on the spectral analysis of the Lax pair, a Riemann–Hilbert problem for the nonlocal two-wave interaction system is constructed. By discussing the solutions of this Riemann–Hilbert problem in both the regular and nonregular cases, we explicitly present the N-soliton solution formula of the nonlocal two-wave interaction system. Moreover,the dynamical behaviour of the single-soliton solution is shown graphically.

关键词： nonlocal two-wave interaction system Riemann–Hilbert problem N-soliton solutions

Interpretation and characterization of rate of penetration intelligent prediction model

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Petroleum Science 2024年第1期21卷 582-596页

作者： Zhi-jun Pei xian-Zhi Song Hai-Tao Wang Yi-qi Shi Shou-Ceng Tian Gen-Sheng Li College of Petroleum Engineering China University of Petroleum(Beijing)Beijing102249China State Key Laboratory of Petroleum Resources and Prospecting Beijing102249China Kunlun Digital Technology Co. Ltd.Beijing102206China

Accurate prediction of the rate of penetration(ROP)is significant for drilling *** the intelligent ROP prediction model based on fully connected neural networks(FNN)outperforms traditional ROP equations and machine learning algorithms,its lack of interpretability undermines its *** study proposes a novel interpretation and characterization method for the FNN ROP prediction model using the Rectified Linear Unit(ReLU)activation *** leveraging the derivative of the ReLU function,the FNN function calculation process is transformed into vector *** FNN model is linearly characterized through further simplification,enabling its interpretation and *** proposed method is applied in ROP prediction scenarios using drilling data from three vertical wells in the Tarim *** results demonstrate that the FNN ROP prediction model with ReLU as the activation function performs exceptionally *** relative activation frequency curve of hidden layer neurons aids in analyzing the overfitting of the FNN ROP model and determining drilling data *** the well sections with similar drilling data,averaging the weight parameters enables linear characterization of the FNN ROP prediction model,leading to the establishment of a corresponding linear representation ***,the quantitative analysis of each feature's influence on ROP facilitates the proposal of drilling parameter optimization schemes for the current well *** established linear characterization equation exhibits high precision,strong stability,and adaptability through the application and validation across multiple well sections.

关键词： Fully connected neural network Explainable artificial intelligence Rate of penetration ReLU active function Deep learning Machine learning

Spiral Wave Dynamics in a Response System Subjected to a Spiral Wave Forcing

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Chinese Physics Letters 2011年第2期28卷 73-76页

作者： LI Guang-Zhao CHEN Yong-qi TANG Guo-Ning LIU jun-xian College of Physics and Technology Guangxi Normal UniversityGuilin 541004

Unidirectional linear error feedback coupling of two excitable medium systems displaying spiral waves is *** spiral wave in the response system is thus subjected to a spiral wave *** find that the unidirectional feedback coupling can lead to richer behaviour than the mutual *** spiral wave dynamics in the response system depends on the coupling strength and frequency *** the coupling strength is small,the feedback coupling induces the drift or meander of the forced spiral *** the coupling strength is large enough,the feedback coupling may lead to the transition from spiral wave to anti-target or target-like *** generation of anti-target wave in coupled excitable media is observed for the first ***,when the coupling strength is strong,the synchronization between two subsystems can be established.

关键词： wave coupling wave

Inhibition Performance of Enhanced-Mo Inhibitor for Carbon Steel in 55% LiBr Solution

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Journal of Iron and Steel Research International 2008年第1期15卷 49-54页

作者： LIANG Cheng-hao HU xian-qi Electromechanics and Materials Engineering College Dalian Maritime University Dalian 116026 Liaoning China School of Chemical Engineering Dalian University of Technology Dalian 116012 Liaoning China

The inhibition performance of enhanced-Mo inhibitor for carbon steel in 55% LiBr solution was measured by means of chemical immersion,electrochemical measurements,and physical detection *** indicated that enhanced-Mo inhibitor showed excellent inhibition performance of carbon steel in 55% LiBr solution,especially at high *** increasing the temperature of solution from 160 ℃ to 240 ℃,the corrosion rates of carbon steel increased from 17.67 μm/a to 33.07 μm/***-Mo inhibitor might improve the anodic polarization performance of carbon steel and widen the passive potential region of carbon steel in 55% LiBr ***-Mo inhibitor belongs to anodic *** 55% LiBr solution,the relationship between corrosion current density icorr and corrosion potential Ecorr of carbon steel accorded with the equation lgicorr=-2.66-3.54Ecorr,and the value of cathodic Tafel constant βc for the H2 reaction was 282 *** 55% LiBr solution contained enhanced-Mo inhibitor,a passive film comprising Fe3O4 and MoO2 was formed on the carbon steel surface by electrochemical *** corrosion of carbon steel might be retarded by this protective film,and the anticorrosion performance of carbon steel in 55% LiBr solution might be improved by enhanced-Mo inhibitor.

关键词： corrosion enhanced-Mo inhibitor carbon steel

Austenite Grain Refinement and Isothermal Growth Behavior in a Low Carbon Vanadium Microalloyed Steel

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Journal of Iron and Steel Research International 2014年第8期21卷 757-764页

作者： Geng-wei YANG Xin-jun SUN qi-long YONG Zhao-dong LI Xiao-xian LI Key Laboratory for Ferrous Metallurgy and Resources Utilization of Ministry of Education Wuhan University of Science and Technology Department of Structural Steel Central Iron and Steel Research Institute Department of Materials Science and Engineering Kunming University of Science and Technology

The austenite grain refinement through control of the grain growth during reheating process after thermomechanical controlled process （TMCP） in a vanadium microalloyed steel was achieved. The formation of ultra-fine grained austenite was attributed to the high density of austenite nucleation at the ferrite/martensite structure and to the inhibition of austenite growth by （Ti~ V）C particles at the relatively low reheating temperature. Corresponding with the precipitation behavior of （Ti,V）C with temperature, the growth behavior of austenite in the vanadium mi- croalloyed steel could be divided into two regions. At lower reheating temperature, austenite grains grew slowly, and ultra-fine grained austenite smaller than 5 ~m was successfully obtained. By contrast, the austenite grains grew rap- idly at high temperature due to the dissolution of （Ti, V）C particles. According to the measured and predicted results of austenite growth kinetics, two models were developed to describe the growth behavior of austenite grains in two different temperature regions, and the apparent activation energy Qapp for grain growth was estimated to be about 115 and 195 kJ/mol, respectively.

关键词： grain refinement austenization (Ti, V) C precipitationl grain growth austenite

The theory of early nonlinear stage of m=1 instability with locally flattened q-profile

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Matter and Radiation at Extremes 2018年第5期3卷 243-247页

作者： Kai-qi Cao xian-Qu Wang Institute of Fusion Science School of Physical Science and TechnologySouthwest Jiaotong UniversityChengduSichuan 610031China

In this paper,we analyze the modification of fast particles on the nonlinear radial displacement of m=1 internal kink mode with a shoulderlike equilibrium current *** the matching method on the solutions of the outer and inner regions,we derive the analytical form of nonlinear radial displacement in the limit of q'=q"=0,which is valid to the cases of weak shear due to a slight flattening of the q(r)profile around q=*** have taken into consideration the effects of the circulating and trapped fast particles on the nonlinear state of the *** is found that a fast particle can modify the nonlinear saturation level by the change of potential energy,depending on the fast particle *** the matching of linear dispersion relation to early nonlinear result,we also obtain the relations of radial displacement to the mode frequency and linear growth rate,and discuss the scaling for different stabilities of the MHD modes.

关键词： Tokamak Magnetohydrodynamics Weak magnetic shear Internal kink mode Fast particle