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A 3D Finite Radon Transform 预览
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作者 Mustapha Boukour Abderrahim El Omri 《数学和系统科学:英文版》 2019年第2期64-69,共6页
The present work is devoted to the development of the extension of FRT (Finite Radon Transform) to the tridimensional case. One simple formulation is proposed and it is shown that it is the exact discretization of the... The present work is devoted to the development of the extension of FRT (Finite Radon Transform) to the tridimensional case. One simple formulation is proposed and it is shown that it is the exact discretization of the continuous Discrete Radon Transform. More precisely this is the case when the sampling is given on a regular grid i.e. the continuous function is filtered by the mean of the box function. Relation of this transform with the Discrete Fourier one is given and is for some help in numerical implementation. 展开更多
关键词 RADON TRANSFORM DISCRETE RADON TRANSFORM FRT DISCRETE FOURIER NUMERICAL COMPUTING
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Solutions in the Discrete Fractional Forms of Two Differential Equations with Singular Points
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作者 Okkes OZTURK 《应用数学学报:英文版》 SCIE CSCD 2019年第3期638-644,共7页
In present note,we apply the Leibniz formula with the nabla operator in discrete fractional calculus(DFC)due to obtain the discrete fractional solutions of a class of associated Bessel equations(ABEs)and a class of as... In present note,we apply the Leibniz formula with the nabla operator in discrete fractional calculus(DFC)due to obtain the discrete fractional solutions of a class of associated Bessel equations(ABEs)and a class of associated Legendre equations(ALEs),respectively.Thus,we exhibit a new solution method for such second order linear ordinary differential equations with singular points. 展开更多
关键词 FRACTIONAL CALCULUS DISCRETE FRACTIONAL CALCULUS DISCRETE FRACTIONAL SOLUTIONS Nabla OPERATOR
Discrete symmetrical perturbation and variational algorithm of disturbed Lagrangian systems
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作者 夏丽莉 戈新生 陈立群 《中国物理B:英文版》 SCIE EI CAS CSCD 2019年第3期77-83,共7页
We investigate the perturbation to discrete conformal invariance and the adiabatic invariants of Lagrangian systems. A variational algorithm is proposed for a system subjected to the perturbation quantities. The discr... We investigate the perturbation to discrete conformal invariance and the adiabatic invariants of Lagrangian systems. A variational algorithm is proposed for a system subjected to the perturbation quantities. The discrete determining equations of the perturbations to conformal invariance are established. For perturbed Lagrangian systems, the condition of the existence of adiabatic invariant is derived from the discrete perturbation to conformal invariance. The numerical simulations demonstrate that the variational algorithm has the higher precision and the longer time stability than the standard numerical method. 展开更多
关键词 VARIATIONAL INTEGRATOR DISCRETE PERTURBATION to conformal INVARIANCE DISCRETE adiabatic INVARIANTS disturbed Lagrangian systems
A holistic computational model for prediction of clay suspension structure 预览
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作者 Yuan Guo Xiong (Bill) Yu 《国际泥沙研究:英文版》 SCIE 2019年第4期345-354,共10页
The formation of clay suspensions involves complex interactions among clay particles subjected to the geochemical environment during the sedimentation process. The structural characteristics have a major influence on ... The formation of clay suspensions involves complex interactions among clay particles subjected to the geochemical environment during the sedimentation process. The structural characteristics have a major influence on the physical and mechanical behavior of the suspension. A modeling framework involving a Discrete Element Method (DEM) model with customized particle mechanical interactions is proposed in this paper for the holistic prediction of the physical structure of clay suspensions. The particle interaction force model is based on the Derjaguin, Landau, Verwey, and Overbeek (DLVO) theory that accounts for electrostatic repulsion, van der Waals attraction, contact repulsion, etc. Kaolinite is used as the model clay to demonstrate the model performance. The surface charge density of kaolinite is obtained through Atomic Force Microscope (AFM) force measurement and is implemented in the particle interaction force model in the subsequent simulations. Influencing factors, such as centrifugal acceleration, ionic concentration, platy structure of particles, and particle size, on the formation of kaolinite suspensions are studied with the numerical model and compare favorably well with the experimental data. This work lays down a unique framework consisting of computational modeling and microscale characterization of clay particles to holistically predict the characteristics of clay suspensions, which paves the basis to model and predict their bulk physical and mechanical behavior. 展开更多
关键词 CLAY SUSPENSION Discrete element method DLVO theory Atomic force MICROSCOPE KAOLINITE Surface potential
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Streamline modeling of fluid transport in naturally fractured porous medium 预览
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作者 ZUO Lihua YU Wei +2 位作者 MIAO Jijun VARAVEI Abdoljalil SEPEHRNOORI Kamy 《石油勘探与开发:英文版》 2019年第1期130-137,共8页
To better understand the roles natural fractures play in porous media, an embedded discrete fracture model and streamline modeling method were combined to model natural fractures and compute the flow trajectory and ti... To better understand the roles natural fractures play in porous media, an embedded discrete fracture model and streamline modeling method were combined to model natural fractures and compute the flow trajectory and time of fluid in matrix and fractures systems. The effects of fracture conductivity, number of fractures and fracture locations on fluid flow trajectory and time were examined through analyzing the differences in water breakthrough time and sweeping volume of reservoirs with different fracture networks. When other conditions are the same, compared with homogeneous reservoir without fractures, the fractured reservoir has water breakthrough time 30% sooner and swept volume 10% smaller. Although increase of single fracture can lead to faster water breakthrough and smaller swept volume, adding more fractures wouldn’t necessarily reach the same effect. The effect of water flooding is also related to the strike and position of fractures. Fractures in different strikes and positions can result in 20% discrepancy in water breakthrough time and 9% gap in swept volume. The shorter the fracture, the less its effect on fluid flow trajectory and time will be. The position of fracture has a strong influence on sweeping efficiency, and the change of one fracture position could bring about 1% variation in swept volume. 展开更多
关键词 MULTIPHASE flow water FLOODING embedded DISCRETE FRACTURE model STREAMLINE simulation natural FRACTURE
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多弹性支撑设备的同步定相振动控制研究 预览
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作者 黄迪 杨铁军 +2 位作者 刘志刚 Michael J.Brennan 李新辉 《船舶与海洋工程学报:英文版》 CSCD 2019年第2期195-204,共10页
This paper describes an analytical investigation into synchrophasing,a vibration control strategy on a machinery installation in which two rotational machines are attached to a beam-like raft by discrete resilient iso... This paper describes an analytical investigation into synchrophasing,a vibration control strategy on a machinery installation in which two rotational machines are attached to a beam-like raft by discrete resilient isolators.Forces and moments introduced by sources are considered,which effectively represent a practical engineering system.Adjusting the relative phase angle between the machines has been theoretically demonstrated to greatly reduce the cost function,which is defined as the sum of velocity squares of attaching points on the raft at each frequency of interest.The effect of the position of the machine is also investigated.Results show that altering the position of the secondary source may cause a slight change to the mode shape of the composite system and therefore change the optimum phase between the two machines.Although the analysis is based on a one-dimensional Euler– Bernoulli beam and each machine is considered as a rigid-body,a key principle can be derived from the results.However,the factors that can influence the synchrophasing control performance would become coupled and highly complicated.This condition has to be considered in practice. 展开更多
关键词 DISCRETE SUPPORTED machines Vibration ISOLATION RAFT Synchrophasing control.Different FORMS of EXCITATIONS
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Diagnosability of a class of discrete event systems based on observations
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作者 S.RESHMILA Devanathan RAJAGOPALAN 《控制理论与技术:英文版》 EI CSCD 2019年第3期265-275,共11页
The diagnosability of discrete event systems has been a topic of interest to many researchers. The diagnosability conditions for various systems have evolved based on a regularity condition that is imposed on faulty t... The diagnosability of discrete event systems has been a topic of interest to many researchers. The diagnosability conditions for various systems have evolved based on a regularity condition that is imposed on faulty traces with respect to their observable continuations. Improving upon this weak but necessary condition, a new model of diagnosability that is based on sensor outputs, which are called observatio ns, upon a command in put is proposed in this paper. Necessary and sufficient con ditions are derived for the proposed diagnosability model. The search performance of the proposed diagnosability condition is of linear complexity in terms of the power set of the system events and observations, compared to the exponential complexity of the search with the existing diag nosability regularity condition. Moreover, a system that is not diag no sable according to the existi ng diag nosability condition may be diagnosable in the proposed diagnosability model, which includes observations. 展开更多
关键词 DISCRETE EVENT system DIAGNOSABILITY FAULT diagnosis mealy AUTOMATA finite state AUTOMATA
Aperiodically intermittent stochastic stabilization via discrete time or delay feedback control
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作者 Lei LIU Matjaz PERC Jinde CAO 《中国科学:信息科学(英文版)》 SCIE EI CSCD 2019年第7期183-195,共13页
In this paper,we present stochastic intermittent stabilization based on the feedback of the discrete time or the delay time.By using the stochastic comparison principle,the Ito formula,and the BorelCantelli lemma,we o... In this paper,we present stochastic intermittent stabilization based on the feedback of the discrete time or the delay time.By using the stochastic comparison principle,the Ito formula,and the BorelCantelli lemma,we obtain two sufficient criteria for stochastic intermittent stabilization.The established criteria show that an unstable system can be stabilized by means of a stochastic intermittent noise via a discrete time feedback if the duration timeτis bounded byτ*.Similarly,stabilization via delay time feedback is equally possible if the lag timeτis bounded byτ**.The upper boundτ*andτ**can be computed numerically by solving corresponding equation. 展开更多
关键词 BROWNIAN motion STOCHASTIC STABILIZATION INTERMITTENT CONTROL discrete time FEEDBACK timedelay FEEDBACK
Voice Recognition by Neuro-Heuristic Method
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作者 Dawid Pofap Marcin Wozniak 《清华大学学报自然科学版(英文版)》 EI CAS CSCD 2019年第1期9-17,共9页
The amount of digital data is increasing every day.At every step of our daily lives,we deal with technologies in which our data are stored (e.g.,mobile phones and laptops),and this is one of the main reasons for the d... The amount of digital data is increasing every day.At every step of our daily lives,we deal with technologies in which our data are stored (e.g.,mobile phones and laptops),and this is one of the main reasons for the design of various types of encryption and user identity verification algorithms.These algorithms are meant not only to fulfill the desire of protecting data but also to address the possibility of granting access of specific digital data to selected individuals.This process brings with it the problem of identity verification.This paper discusses the problem of voice verification and presents a voice verification method based on artificial intelligence methods. Numerous tests are performed herein to demonstrate the effectiveness of the presented solution.The research results are shown and discussed in terms of the advantages and disadvantages of the solution. 展开更多
关键词 neural network HEURISTIC ALGORITHMS DISCRETE FOURIER TRANSFORM (DFT) image processin
基于离散型制造企业的技术标准体系构建研究
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作者 杨汉 秦华 《模具工业》 2019年第1期7-10,共4页
企业技术标准体系是企业生产、经营、管理的技术依据,且各企业(行业)由于其特点,构建路径又有差别,在分析离散型制造企业汽车模具标准化现状和常用技术标准体系架构分类的基础上,以企业为例,并以标准化方法论为指导,阐释了汽车模具行业... 企业技术标准体系是企业生产、经营、管理的技术依据,且各企业(行业)由于其特点,构建路径又有差别,在分析离散型制造企业汽车模具标准化现状和常用技术标准体系架构分类的基础上,以企业为例,并以标准化方法论为指导,阐释了汽车模具行业技术标准体系的构建方案和实施策略,以期夯实企业的技术基础管理。 展开更多
关键词 技术标准体系 汽车模具 离散型 构建
Designing waste rock barriers by advanced numerical modelling 预览
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作者 Klaus Thoeni Martin Servin +1 位作者 Scott W.Sloan Anna Giacomini 《岩石力学与岩土工程学报:英文版》 CSCD 2019年第3期659-675,共17页
Design of waste rock barriers forming safety berms for haul trucks requires knowledge of complex interactions which cannot readily be tested by physical means.An advanced numerical model based on non-smooth multi-doma... Design of waste rock barriers forming safety berms for haul trucks requires knowledge of complex interactions which cannot readily be tested by physical means.An advanced numerical model based on non-smooth multi-domain mechanics is presented together with model calibration using limited fullscale experimental data.Waste rock is represented by spherical particles with rolling resistance,and an ultra-class haul truck is represented by a rigid multibody system interconnected with mechanical joints.The model components are first calibrated and then the calibrated model is used for simulating various collision scenarios with different approach conditions and safety berm geometries.Numerical predictions indicate that the width of the berm is most critical for efficiently stopping a runaway truck.The model can also predict if a certain berm geometry is capable of stopping a runaway truck.Results are summarised in a series of diagrams intended for use as design guidelines by practitioners and engineers. 展开更多
关键词 Discrete element method(DEM) MULTIBODY dynamics(MBD) NON-SMOOTH multi-domain DYNAMICS Granular materials Ultra-class HAUL truck Safety BERM Surface mining
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PERMANENCE OF A DISCRETE LOGISTIC EQUATION WITH PURE TIME DELAYS
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作者 Yangyang Lü Lijuan Chen Liujuan Chen 《应用数学年刊:英文版》 2019年第1期63-70,共8页
In this paper we propose a discrete logistic system with pure delays. By giving the detail analysis of the right-hand side functional of the system, we consider its permanence property which is one of the most importa... In this paper we propose a discrete logistic system with pure delays. By giving the detail analysis of the right-hand side functional of the system, we consider its permanence property which is one of the most important topic in the study of population dynamics. The results obtained in this paper are good extensions of the existing results to the discrete case. Also we give an example to show the feasibility of our main results. 展开更多
关键词 PERMANENCE DISCRETE DELAY LOGISTIC system
Kinetic Simulation of Nonequilibrium Kelvin-Helmholtz Instability
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作者 林传栋 Kai H.Luo +1 位作者 甘延标 刘枝朋 《理论物理通讯:英文版》 SCIE CAS CSCD 2019年第1期132-142,共11页
The recently developed discrete Boltzmann method(DBM), which is based on a set of uniform linear evolution equations and has high parallel efficiency, is employed to investigate the dynamic nonequilibrium process of K... The recently developed discrete Boltzmann method(DBM), which is based on a set of uniform linear evolution equations and has high parallel efficiency, is employed to investigate the dynamic nonequilibrium process of Kelvin-Helmholtz instability(KHI). It is found that, the relaxation time always strengthens the global nonequilibrium(GNE), entropy of mixing, and free enthalpy of mixing. Specifically, as a combined effect of physical gradients and nonequilibrium area, the GNE intensity first increases but decreases during the whole life-cycle of KHI. The growth rate of entropy of mixing shows firstly reducing, then increasing, and finally decreasing trends during the KHI process. The trend of the free enthalpy of mixing is opposite to that of the entropy of mixing. Detailed explanations are:(i) Initially,binary diffusion smooths quickly the sharp gradient in the mole fraction, which results in a steeply decreasing mixing rate.(ii) Afterwards, the mixing process is significantly promoted by the increasing length of material interface in the evolution of the KHI.(iii) As physical gradients are smoothed due to the binary diffusion and dissipation, the mixing rate reduces and approaches zero in the final stage. Moreover, with the increasing Atwood number, the global strength of viscous stresses on the heavy(light) medium reduces(increases), because the heavy(light) medium has a relatively small(large) velocity change. Furthermore, for a smaller Atwood number, the peaks of nonequilibrium manifestations emerge earlier, the entropy of mixing and free enthalpy of mixing change faster, because the KHI initiates a higher growth rate. 展开更多
关键词 DISCRETE BOLTZMANN METHOD KELVIN-HELMHOLTZ INSTABILITY NONEQUILIBRIUM effect
Mechanism of toppling and deformation in hard rock slope: a case of bank slope of Hydropower Station, Qinghai Province, China
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作者 CAI Jun-chao JU Neng-pan +4 位作者 HUANG Run-qiu ZHENG Da ZHAO Wei-hua LI Long-qi HUANG Jian 《山地科学学报:英文版》 SCIE CSCD 2019年第4期924-934,共11页
Recently, various toppling slopes have emerged with the development of hydropower projects in the western mountainous regions of China. The slope on the right bank of the Laxiwa Hydropower Station, located on the main... Recently, various toppling slopes have emerged with the development of hydropower projects in the western mountainous regions of China. The slope on the right bank of the Laxiwa Hydropower Station, located on the mainstream of the Yellow River in the Qinghai Province of Northwest China, is a typical hard rock slope. Further, its deformation characteristics are different from those of common natural hard rock toppling. Because this slope is located close to the dam of the hydropower station, its deformation mechanism has a practical significance. Based on detailed geological engineering surveys, four stages of deformation have been identified using discrete element numerical software and geological engineering analysis methods, including toppling creep, initial toppling deformation, intensified toppling deformation, and current slope formation. The spatial and time-related deformation of this site also exhibited four stages, including initial toppling, toppling development, intensification of toppling, and disintegration and collapse. Subsequently, the mechanism of toppling and deformation of the bank slope were studied. The results of this study exhibit important reference value for developing the prevention–control design of toppling and for ensuring operational safety in the hydropower reservoir area. 展开更多
关键词 LAXIWA HYDROPOWER Station Hard rock SLOPE Toppling DEFORMATION MECHANISM Discrete element method SLOPE failure
EULER SCHEME FOR FRACTIONAL DELAY STOCHASTIC DIFFERENTIAL EQUATIONS BY ROUGH PATHS TECHNIQUES 预览
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作者 Johanna GARZON Samy TINDEL Soledad TORRES 《数学物理学报:B辑英文版》 SCIE CSCD 2019年第3期747-763,共17页
In this note, we study a discrete time approximation for the solution of a class of delayed stochastic differential equations driven by a fractional Brownian motion with Hurst parameter H ∈(1/2,1). In order to prove ... In this note, we study a discrete time approximation for the solution of a class of delayed stochastic differential equations driven by a fractional Brownian motion with Hurst parameter H ∈(1/2,1). In order to prove convergence, we use rough paths techniques. Theoretical bounds are established and numerical simulations are displayed. 展开更多
关键词 FRACTIONAL BROWNIAN motion stochastic differential equations ROUGH paths discrete time APPROXIMATION
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离散Leslie-Gower食物链模型的动力学行为研究 预览
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作者 苏倩倩 《数学杂志》 2019年第1期53-59,共7页
本文研究了一类离散Leslie-Gower三维食物链模型动力学行为.利用差分不等式,获得了在一定的条件下种群x1;x3持久而x2绝灭,然后构造适当的差分Lyapunov函数,得到了该系统全局吸引性的充分性条件,推广了Huo在文[2]中的结果.
关键词 离散 食物链 持久性 绝灭性 全局吸引性
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A note on “Lattice soliton equation hierarchy and associated properties”
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作者 徐西祥 郭敏 《中国物理B:英文版》 SCIE EI CAS CSCD 2019年第1期669-670,共2页
We demonstrate that the new hierarchy of integrable lattice equations in Chin. Phys. B 21 090202(2012) can be changed into the integrable lattice hierarchy in Chin. Phys. B 13 1009(2004) by using a very simple transfo... We demonstrate that the new hierarchy of integrable lattice equations in Chin. Phys. B 21 090202(2012) can be changed into the integrable lattice hierarchy in Chin. Phys. B 13 1009(2004) by using a very simple transformation. 展开更多
关键词 INTEGRABLE lattice HIERARCHY transformation between POTENTIALS discrete zero CURVATURE equation LAX PAIR
考虑异质车流的信号交叉口实时排队估计 预览
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作者 陈之锴 成卫 +1 位作者 李黎山 李冰 《物流科技》 2019年第5期73-78,共6页
信号交叉口排队长度是交通信号控制的一项重要指标,为了提高排队估计精度以及实用性,文章以相邻信号交叉口的下游交叉口排队长度作为研究对象,在关联信号交叉口排队长度计算模型基础上,提出了一种考虑异质车流的影响下的实时排队长度的... 信号交叉口排队长度是交通信号控制的一项重要指标,为了提高排队估计精度以及实用性,文章以相邻信号交叉口的下游交叉口排队长度作为研究对象,在关联信号交叉口排队长度计算模型基础上,提出了一种考虑异质车流的影响下的实时排队长度的估计方法。通过异质车流的行程时间,拟合双峰模型得到车辆离散模型,研究表明:利用该模型分析上游车辆离去流量,得到下游到达流率;通过信号控制方案以及停车波波速,估计交叉口车辆排队长度。大量实证研究检验平均绝对误差在0.3veh/lane/s内,提高了信号交叉口排队长度估计的有效性与实用性,从而为后续异质交通环境下信号配时优化提供理论依据。 展开更多
关键词 智能交通 排队实时估计 离散 异质车流
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离散粒子群优化算法求解多目标柔性作业车间调度问题 预览
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作者 喻明让 陈云 张志刚 《制造技术与机床》 北大核心 2019年第1期159-165,共7页
对多目标柔性作业车间调度优化问题进行研究,提出了一种基于Pareto档案的离散粒子群优化算法。在该算法中,种群中的粒子通过与其自身历史最优位置(pbest)以及种群全局最优位置(gbest)的交叉实现粒子位置的更新。对于多目标优化问题来说... 对多目标柔性作业车间调度优化问题进行研究,提出了一种基于Pareto档案的离散粒子群优化算法。在该算法中,种群中的粒子通过与其自身历史最优位置(pbest)以及种群全局最优位置(gbest)的交叉实现粒子位置的更新。对于多目标优化问题来说,一次迭代可能产生多个gbest,引入一个Pareto档案用于保存迭代产生的优秀个体。并将Pareto档案维护与gbest选择同时进行以确保Pareto档案中的个体必然为一些粒子的gbest。进而将变异操作引入到粒子群算法以增强其局部搜索能力。最后,将该算法应用于几个典型实例,并通过与几种已有算法的对比验证了其有效性。 展开更多
关键词 柔性作业车间调度 多目标优化 Pareto档案 离散 粒子群优化算法
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Variable exponent Hardy spaces associated with discrete Laplacians on graphs
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作者 Victor Almeida Jorge J.Betancor +1 位作者 Alejandro J.Castro Lourdes Rodriguez-Mesa 《中国科学:数学英文版》 SCIE CSCD 2019年第1期73-124,共52页
In this paper we develop the theory of variable exponent Hardy spaces associated with discrete Laplacians on infinite graphs. Our Hardy spaces are defined by square integrals, atomic and molecular decompositions. Also... In this paper we develop the theory of variable exponent Hardy spaces associated with discrete Laplacians on infinite graphs. Our Hardy spaces are defined by square integrals, atomic and molecular decompositions. Also we study boundedness properties of Littlewood-Paley functions, Riesz transforms, and spectral multipliers for discrete Laplacians on variable exponent Hardy spaces. 展开更多
关键词 GRAPHS discrete LAPLACIAN HARDY SPACES variable EXPONENT square functions spectral MULTIPLIERS
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