检索结果-南通市图书馆

Efficient Dual Algorithms for Image Segmentation Using TV-Allen-Cahn Type Models

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Communications in Computational Physics 2011年第4期9卷 859-877页

作者： li-lian wang Ying Gu Division of Mathematical Sciences School of Physical and Mathematical SciencesNanyang Technological University637371Singapore

Variational image segmentation based on the Mumford and Shah model[31],together with implementation by the piecewise constant level-set method(PCLSM)[26],leads to fully nonlinear Total Variation(TV)-Allen-Cahn *** commonlyused numerical approaches usually suffer from the difficulties not only with the nondifferentiability of the TV-term,but also with directly evolving the discontinuous piecewise constant-structured *** this paper,we propose efficient dual algorithms to overcome these *** use of a splitting-penalty method results in TVAllen-Cahn type models associated with different"double-well"potentials,which allow for the implementation of the dual algorithm of Chambolle[8].Moreover,we present a new dual algorithm based on an edge-featured penalty of the dual variable,which only requires to solve a vectorial Allen-Cahn type equation with linear∇(div)-diffusion rather than fully nonlinear diffusion in the Chambolle’s ***,more efficient numerical algorithms such as time-splitting method and Fast Fourier Transform(FFT)can be *** numerical tests show that two dual algorithms are much faster and more stable than the primal gradient descent approach,and the new dual algorithm is at least as efficient as the Chambolle’s algorithm but is more *** demonstrate that the new method also provides a viable alternative for image restoration.

关键词： Variational models image segmentation TV-Allen-Cahn type equations dual algorithms splitting-penalty methods FFT.

On Spectral Approximations by Generalized Slepian Functions

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Numerical Mathematics(Theory,Methods and Applications) 2011年第2期4卷 296-318页

作者： Jing Zhang li-lian wang Division of Mathematical Sciences School of Physical and Mathematical SciencesNanyang Technological University637371Singapore

We introduce a family of orthogonal functions,termed as generalized Slepian functions(GSFs),closely related to the time-frequency concentration problem on a unit disk in ***[19].These functions form a complete orthogonal system in L_(ωα)^(2)(−1,1)with̟ω_(α)(x)=(1−x)^(α),α>−1,and can be viewed as a generalization of the Jacobi polynomials with parameter(α,0).We present various analytic and asymptotic properties of GSFs,and study spectral approximations by such functions.

关键词： Generalized Slepian functions orthogonal systems approximation errors spectral accuracy

A MULTI-DOMAIN SPECTRAL IPDG METHOD FOR HELMHOLTZ EQUATION WITH HIGH WAVE NUMBER

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Computational Mathematics 2013年第2期31卷 107-136页

作者： Lunji Song Jing Zhang li-lian wang School of Mathematics and Statistics Lanzhou University Lanzhou 730000 China School of Mathematics and Statistics Huazhong Normal University Wuhan ~300~9 China Division of Mathematical Sciences School of Physical and Mathematical Sciences Nanyang Technological University 637371 Singapore

This paper is concerned with a multi-domain spectral method, based on an interior penalty discontinuous Galerkin （IPDG） formulation, for the exterior Helmholtz problem truncated via an exact circular or spherical Dirichlet-to-Neumann （DtN） boundary con- dition. An effective iterative approach is proposed to localize the global DtN boundary condition, which facilitates the implementation of multi-domain methods, and the treat- ment for complex geometry of the scatterers. Under a discontinuous Galerkin formulation, the proposed method allows to use polynomial basis functions of different degree on dif- ferent subdomains, and more importantly, explicit wave number dependence estimates of the spectral scheme can be derived, which is somehow implausible for a multi-domain continuous Galerkin formulation.

关键词： Helmholtz equation High wavenumber Global DtN boundary condition IPDG Multli-domain spectral method.

A New Triangular Spectral Element Method II: Mixed Formulation and hp-Error Estimates

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Numerical Mathematics(Theory,Methods and Applications) 2019年第1期12卷 72-97页

作者： Bingzhen Zhou Bo wang li-lian wang Ziqing Xie Key Laboratory of High Performance Computing and Stochastic Information Processing(HPCSIP) College of Mathematics and StatisticsHunan Normal UniversityChangsha 410081P.R.China Division of Mathematical Sciences School of Physical and Mathematical SciencesNanyang Technological University637371Singapore

Mixed triangular spectral element method using nodal basis on unstructured meshes is investigated in this *** method is based on equivalent first order system of the elliptic problem and rectangle-triangle *** fully enjoys the ten-sorial structure and flexibility in handling complex domains by using nodal basis and unstructured triangular *** from the usual Galerkin formulation,the mixed form is particularly advantageous in this context,since it can avoid the singularity in-duced by the rectangle-triangle transform in the calculation of the matrices,and does not require the evaluation of the stiffness *** hp a priori error estimate is pres-ented for the proposed *** implementation details and some numerical exam-ples are provided to validate the accuracy and flexibility of the method.

关键词： Triangular spectral element method hp error analysis mixed form interpolation error in H^(1)-norm

Some Recent Advances on SpectralMethods for Unbounded Domains

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Communications in Computational Physics 2009年第2期5卷 195-241页

作者： Jie Shen li-lian wang Department of Mathematics Purdue UniversityWest LafayetteIN47907USA Division of Mathematical Sciences School of Physical and Mathematical SciencesNanyang Technological University637616Singapore

We present in this paper a unified framework for analyzing the spectral methods in unbounded domains using mapped Jacobi,Laguerre and Hermite functions.A detailed comparison of the convergence rates of these spectral methods for solutions with typical decay behaviors is carried out,both theoretically and computationally.A brief review on some of the recent advances in the spectral methods for unbounded domains is also presented.

关键词： Spectral method unbounded domain orthogonal polynomials rational functions Hermite functions Laguerre functions

A New Spectral Method Using Nonstandard Singular Basis Functions for Time-Fractional Differential Equations

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Communications on Applied Mathematics and Computation 2019年第2期1卷 207-230页

作者： Wenjie liu li-lian wang Shuhuang Xiang Department of Mathematics Harbin Institute of TechnologyHarbin 150001China Division of Mathematical Sciences School of Physical and Mathematical SciencesNanyang Technological UniversitySingapore 637371Singapore Mathematics and Statistics Central South UniversityChangsha 410083China

In this paper,we introduce new non-polynomial basis functions for spectral approximation of time-fractional partial differential equations (PDEs). Different from many other approaches,the nonstandard singular basis functions are defined from some generalised Birkhoff interpolation problems through explicit inversion of some prototypical fractional initial value problem (FIVP) with a smooth source term. As such,the singularity of the new basis can be tailored to that of the singular solutions to a class of time-fractional PDEs,leading to spectrally accurate approximation. It also provides the acceptable solution to more general singular problems.

关键词： Fractional differential equations Generalised Birkhoff interpolation Nonstandard singular basis function

An Efficient and Accurate Spectral Method for Acoustic Scattering in Elliptic Domains

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Numerical Mathematics(Theory,Methods and Applications) 2009年第3期2卷 258-274页

作者： Qirong Fang Jie Shen li-lian wang Department of Mathematics Purdue University West Lafayette IN 47907 USA. Division of Mathematical Sciences School of Physical and MathematicalSciences Nanyang Technological University 637616 Singapore.

An efficient and accurate method for solving the two-dimensional Helmholtz equation in domains exterior to elongated obstacles is developed in this *** method is based on the so called transformed field expansion(TFE) coupled with a spectral-Galerkin solver for elliptical domain using Mathieu *** results are presented to show the accuracy and stability of the proposed method.

关键词： Acoustic scattering high-order methods boundary perturbations spectral-Galerkinmethods.

Dissolvable temporary barrier:a novel paradigm for flexible hydrogel patterning in organ-on-a-chip models

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Bio-Design and Manufacturing 2024年第2期7卷 153-166页

作者： Ding wang Qinyu li Chenyang Zhou Zhangjie li Kangyi Lu Yijun liu lian Xuan Xiaolin wang Department of Micro/Nano Electronics School of Electronic Information and Electrical EngineeringShanghai Jiao Tong UniversityShanghai 200240China Department of Ophthalmology LKS Faculty of MedicineThe University of Hong KongHong Kong 999077China Institute of Medical Robotics Shanghai Jiao Tong UniversityShanghai 200240China National Key Laboratory of Advanced Micro and Nano Manufacture Technology Shanghai Jiao Tong UniversityShanghai 200240China National Center for Translational Medicine(Shanghai)SHU Branch Shanghai UniversityShanghai 200444China

A combination of hydrogels and microfluidics allows the construction of biomimetic three-dimensional(3D)tissue models in vitro,which are also known as *** hydrogel patterningwith awell-controlled spatial distribution is typically achieved by embedding sophisticated microstructures to act as a ***,these physical barriers inevitably expose cells/tissues to a less physiologically relevant microenvironment than in vivo ***,we present a novel dissolvable temporary barrier(DTB)strategy that allows robust and flexible hydrogel patterning with great freedom of design and desirable flow stimuli for cellular *** key aspect of this approach is the patterning of a water-soluble rigid barrier as a guiding path for the hydrogel using stencil printing technology,followed by a barrier-free medium perfusion after the dissolution of the *** and multiple tissue compartments with different geometries can be established using either straight or curved DTB *** effectiveness of this strategy is further validated by generating a 3D vascular network through vasculogenesis and angiogenesis using a vascularized microtumor *** a new proof-of-concept in vasculature-on-a-chip,DTB enables seamless contact between the hydrogel and the culture medium in closed microdevices,which is an improved protocol for the fabrication ofmultiorgan ***,we expect it to serve as a promising paradigm for organ-on-a-chip devices for the development of tumor vascularization and drug evaluation in the future preclinical studies.

关键词： Dissolvable temporary barrier Hydrogel patterning Microfluidics Organ-on-a-chip Vascularization

Molecularly imprinted sensor based on carboxylated carbon nanotubes/Keggin-type polyoxometalates nanocomposite for the detection of furazolidone

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Tungsten 2024年第2期6卷 394-409页

作者： Yu-Lan Huang Bing Zhang Yu-lian li li wang Le Dong Jian li College of Ocean Food and Biological Engineering Jimei UniversityXiamen 361021China College of Oceanology and Food Science Quanzhou Normal UniversityQuanzhou 362000China

Due to its properties of mutagenic,teratogenic,and carcinogenic,the detection of furazolidone(FZD)in aquaculture is of great importance for food safety and human *** this study,molecularly imprinted fi lms modifi ed with carboxylated multi-walled carbon nanotube-phosphomolybdic acid composite were used to fabricate an electrochemical sensor for the determination of *** nanocomposites were characterized using infrared spectroscopy,scanning electron microscopy,energy-dispersive X-ray spectroscopy,and X-ray diff *** electrochemical characteristics of the modifi ed electrodes were examined using electrochemical impedance spectroscopy,cyclic voltammetry,and diff erential pulse *** sensor exhibited exceptional catalytic *** calibration curves were acquired in the concentration range of 6 nmol·L^(−1)to 0.6μmol·L^(−1),with a limit of detection of 3.38 nmol·L^(−1).Additionally,the sensor proved successful in recognizing FZD in shrimp samples with satisfactory recoveries and *** method provides a strategy to construct a molecularly imprinted electrochemical sensing platform using nanomaterials,which has great promise in the field of food safety.

关键词： Phosphomolybdate Furazolidone Polyoxometalates Carboxylated multi-walled carbon nanotube Molecularly imprinted polymers Electrochemical sensor