检索结果-南通市图书馆

Anomalous Sorption Kinetics of Self-Interacting Particles by a Spherical Trap

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 2022年第3期31卷 707-738页

作者： Antonio Raudino Antonio Grassi Giuseppe Lombardo giovanni russo Clarissa Astuto Mario Corti Department of Chemical Sciences University of CataniaViale A.Doria 6-95125CataniaItaly Department of Mathematics University of CataniaViale A.Doria 6-95125 CataniaItaly Applied Mathematics and Computational Science King Abdullah University of Science and Technology(KAUST)4700ThuwalSaudi Arabia CNR-IPCF Viale F.Stagno d’Alcontres 3798158 MessinaItaly

In this paper we propose a computational framework for the investigation of the correlated motion between positive and negative ions exposed to the attraction of a bubble surface that mimics the(oscillating)cell membrane.Specifically we aim to investigate the role of surface traps with substances freely diffusing around the cell.The physical system we want to model is an anchored gas drop submitted to a diffusive flowof charged surfactants(ions).When the diffusing surfactantsmeet the surface of the bubble,they are reversibly adsorbed and their local concentration is accurately measured.The correlated diffusion of surfactants is described by a Poisson-Nernst-Planck(PNP)system,in which the drift term is given by the gradient of a potential which includes both the effect of the bubble and the Coulomb interaction between the carriers.The latter term is obtained from the solution of a self-consistent Poisson equation.For very short Debye lengths one can adopt the so called Quasi-Neutral limit which drastically simplifies the system,thus allowing for much faster numerical simulations.The paper has four main objectives.The first one is to present a PNP model that describes ion charges in presence of a trap.The second one is to provide benchmark tests for the validation of simplified multiscale models under current development[1].The third one is to explore the relevance of the term describing the interaction among the apolar tails of the anions.The last one is to quantitatively explore the validity of the Quasi-Neutral limit by comparison with detailed numerical simulation for smaller and smaller Debye lengths.In order to reach these goals,we propose a simple and efficient Alternate Direction Implicit method for the numerical solution of the non-linear PNP system,which guarantees second order accuracy both in space and time,without requiring solution of nonlinear equation at each time step.New semi-implicit scheme for a simplified PNP system near quasi neutrality is also proposed.

关键词： Spherycal trap quasi-neutrality finite differences Coulomb potential Poisson-Nernst-Planck system ADI discretization semi-implicit scheme

Central Schemes and Second Order Boundary Conditions for 1D Interface and Piston Problems in Lagrangian Coordinates

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 2010年第9期8卷 797-822页

作者： Riccardo Fazio giovanni russo Department of Mathematics University of MessinaSalita Sperone 3198166 MessinaItaly Department of Mathematics and Computer Science University of CataniaViale Andrea Doria 695125 CataniaItaly

We study high-resolution central schemes in Lagrangian coordinates for the one-dimensional system of conservation laws describing the evolution of two gases in slab geometry separated by an interface.By using Lagrangian coordinates,the interface is transformed to a fixed coordinate in the computational domain and,as a consequence,the movement of the interface is obtained as a byproduct of the numerical solution.The main contribution is the derivation of a special equation of state to be imposed at the interface in order to avoid non-physical oscillations.Suitable boundary conditions at the piston that guarantee second order convergence are described.We compare the solution of the piston problem to other results available in the literature and to a reference solution obtained within the adiabatic approximation.A shock-interface interaction problem is also treated.The results on these tests are in good agreement with those obtained by other methods.

关键词： Lagrangian central schemes Euler equations interface conditions boundary conditions

Second Order Multigrid Methods for Elliptic Problems with Discontinuous Coefficients on an Arbitrary Interface, I: One Dimensional Problems

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) 2012年第1期5卷 19-42页

作者： Armando Coco giovanni russo Dipartimento di Matematica e Informatica Universitàdi CataniaViale Andrea Doria695125CataniaItaly

In this paper we present a one dimensional second order accurate method to solve Elliptic equations with discontinuous coefficients on an arbitrary interface.Second order accuracy for the first derivative is obtained as well.The method is based on the Ghost Fluid Method,making use of ghost points on which the value is defined by suitable interface conditions.The multi-domain formulation is adopted,where the problem is split in two sub-problems and interface conditions will be enforced to close the problem.Interface conditions are relaxed together with the internal equations(following the approach proposed in[10]in the case of smooth coefficients),leading to an iterative method on all the set of grid values(inside points and ghost points).A multigrid approach with a suitable definition of the restriction operator is provided.The restriction of the defect is performed separately for both sub-problems,providing a convergence factor close to the one measured in the case of smooth coefficient and independent on the magnitude of the jump in the coefficient.Numerical tests will confirm the second order accuracy.Although the method is proposed in one dimension,the extension in higher dimension is currently underway[12]and it will be carried out by combining the discretization of[10]with the multigrid approach of[11]for Elliptic problems with non-eliminated boundary conditions in arbitrary domain.

关键词： Elliptic equation discontinuous coefficient second order accuracy multigrid arbitrary interface jump conditions

ASecond-Order Finite-Difference Method for Compressible Fluids in Domains with Moving Boundaries

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 2018年第1期23卷 230-263页

作者： Alina Chertock Armando Coco Alexander Kurganov giovanni russo Department of Mathematics North Carolina State UniversityRaleighNC 27695USA Department of Mechanical Engineering and Mathematical Sciences Oxford Brookes UniversityOxford OX331HXUK Department of Mathematics Southern University of Science and TechnologyShenzhenGuangdong 518055China and Mathematics DepartmentTulane UniversityNew OrleansLA 70118USA Dipartimento diMatematica ed Informatica Universit`a di Catania95125CataniaItaly.

In this paper,we describe how to construct a finite-difference shockcapturing method for the numerical solution of the Euler equation of gas dynamics on arbitrary two-dimensional domainΩ,possibly with moving boundary.The boundaries of the domain are assumed to be changing due to the movement of solid objects/obstacles/walls.Although the motion of the boundary could be coupled with the fluid,all of the numerical tests are performed assuming that such a motion is prescribed and independent of the fluid flow.The method is based on discretizing the equation on a regular Cartesian grid in a rectangular domainΩ_(R)⊃Ω.Ωe identify inner and ghost points.The inner points are the grid points located insideΩ,while the ghost points are the grid points that are outsideΩbut have at least one neighbor insideΩ.The evolution equations for inner points data are obtained from the discretization of the governing equation,while the data at the ghost points are obtained by a suitable extrapolation of the primitive variables(density,velocities and pressure).Particular care is devoted to a proper description of the boundary conditions for both fixed and time dependent domains.Several numerical experiments are conducted to illustrate the validity of themethod.Ωe demonstrate that the second order of accuracy is numerically assessed on genuinely two-dimensional problems.

关键词： Compressible fluids Euler equations of gas dynamics ghost-cell extrapolation moving boundaries finite-difference shock-capturing methods

A Second Order Finite-Difference Ghost-Point Method for Elasticity Problems on Unbounded Domains with Applications to Volcanology

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 2014年第9期16卷 983-1009页

作者： Armando Coco Gilda Currenti Ciro Del Negro giovanni russo Dipartimento di Scienze della Terra e Geoambientali Universita di Bari Aldo MoroBariItaly. Bristol University Queens RoadBristol BS81RJUnited Kingdom. Istituto Nazionale di Geofisica e Vulcanologia Italy. Dipartimento di Matematica e Informatica Universita di CataniaCataniaItaly

We propose a finite-difference ghost-point approach for the numerical solution of Cauchy-Navier equations in linear elasticity problems on arbitrary unbounded domains.The technique is based on a smooth coordinate transformation,which maps an unbounded domain into a unit square.Arbitrary geometries are defined by suitable level-set functions.The equations are discretized by classical nine-point stencil on interior points,while boundary conditions and high order reconstructions are used to define the field variables at ghost-points,which are grid nodes external to the domain with a neighbor inside the domain.The linear system arising from such discretization is solved by a multigrid strategy.The approach is then applied to solve elasticity problems in volcanology for computing the displacement caused by pressure sources.The method is suitable to treat problems in which the geometry of the source often changes(explore the effects of different scenarios,or solve inverse problems in which the geometry itself is part of the unknown),since it does not require complex re-meshing when the geometry is modified.Several numerical tests are successfully performed,which asses the effectiveness of the present approach.

关键词： Linear elasticity Cauchy-Navier equations ground deformation unbounded domain coordinate transformation method Cartesian grid ghost points level-set methods multigrid.

High Order Conservative Semi-Lagrangian Scheme for the BGK Model of the Boltzmann Equation

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 2021年第1期29卷 1-56页

作者： Sebastiano Boscarino Seung-Yeon Cho giovanni russo Seok-Bae Yun Department of Mathematics and Computer Science University of Catania95125 CataniaItaly Department of Mathematics Sungkyunkwan UniversitySuwon 440-746Republic of Korea

In this paper,we present a conservative semi-Lagrangian finite-difference scheme for the BGK model.Classical semi-Lagrangian finite difference schemes,coupled with an L-stable treatment of the collision term,allow large time steps,for all the range of Knudsen number[17,27,30].Unfortunately,however,such schemes are not conservative.Lack of conservation is analyzed in detail,and two main sources are identified as its cause.First,when using classical continuous Maxwellian,conservation error is negligible only if velocity space is resolved with sufficiently large number of grid points.However,for a small number of grid points in velocity space such error is not negligible,because the parameters of the Maxwellian do not coincide with the discrete moments.Secondly,the non-linear reconstruction used to prevent oscillations destroys the translation invariance which is at the basis of the conservation properties of the scheme.As a consequence the schemes show a wrong shock speed in the limit of small Knudsen number.To treat the first problem and ensure machine precision conservation of mass,momentum and energy with a relatively small number of velocity grid points,we replace the continuous Maxwellian with the discrete Maxwellian introduced in[22].The second problem is treated by implementing a conservative correction procedure based on the flux difference form as in[26].In this way we can construct conservative semi-Lagrangian schemes which are Asymptotic Preserving(AP)for the underlying Euler limit,as the Knudsen number vanishes.The effectiveness of the proposed scheme is demonstrated by extensive numerical tests.

关键词： BGK model Boltzmann equation semi-Lagrangian scheme conservative correction discrete Maxwellian

Transperineal laser ablation of the prostate as a treatment for benign prostatic hyperplasia and prostate cancer: The results of a Delphi consensus project

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Asian Journal of Urology 2024年第2期11卷 271-279页

作者： Andrea Cocci Marta Pezzoli Fernando Bianco Franco Blefari Pierluigi Bove Francois Cornud Gaetano De Rienzo Paolo Destefanis Danilo Di Trapani Alessandro Giacobbe Luca Giovanessi Antonino Laganà giovanni Lughezzani Guglielmo Manenti Gianluca Muto Gianluigi Patelli Novello Pinzi Stefano Regusci Giorgio I.russo Juan I.M.Salamanca Matteo Salvi Luigi Silvestri Fabrizio Verweij Eric Walser Riccardo GBertolo Valerio Iacovelli Alessandro Bertaccini Debora Marchiori Hugo Davila Pasquale Ditonno Paolo Gontero Gennaro Iapicca Theo M De Reijke Vito Ricapito Pierluca Pellegrini Andrea Minervini Sergio Serni Francesco Sessa Department of Urology Careggi HospitalUniversity of FlorenceFlorenceItaly Urology Section University of FlorenceFlorenceItaly Urological Research Network MiamiFLUSA Urology Section Prato HospitalPratoItaly Torvergata Oncoscience Research Centre of Excellence TORDepartment of Experimental MedicineUniversity of Rome Tor VergataRomeItaly Department of Urology San Carlo di Nancy HospitalRomeItaly Department of Radiology Hôpital CochinParis Descartes UniversityParisFrance Urology and Andrology Unit II Department of Emergency and Organ TransplantationUniversity of BariBariItaly Unit of Urology Cittàdella Salute e della Scienza HospitalUniversity of TurinTurinItaly Urology Unit Buccheri La Ferla Fatebenefratelli HospitalPalermoItaly Department of Urology Humanitas Gradenigo HospitalTurinItaly Urology Unit Surgical DepartmentFondazione Poliambulanza Istituto OspedalieroBresciaItaly Departement of Urology “S.Giovanni Evangelista”HospitalTivoliItaly Humanitas Clinical and Research CentereIRCCS Department of UrologyRozzanoItaly Department of Biomedical Sciences Humanitas UniversityPieve EmanueleItaly Department of Biomedicine and Prevention University of Rome“Tor Vergata”RomeItaly Department of Diagnostic Imaging and Interventional Radiology University of Rome“Tor Vergata”RomeItaly Department of Interventional Radiology Pesenti-Fenaroli Hospital-ASST Bergamo EstAlzano LombardoItaly Department of Urology University of SienaSienaItaly Swiss International Prostate Center GenevaSwitzerland Clinique Générale Beaulieu GenevaSwitzerland Department of Urology University of CataniaItaly Department of Urology Puerta de Hierro-Majadahonda University HospitalMadridSpain Lyx Institute of Urology Universidad Francisco de VitoriaMadridSpain Department of Medico-Surgical Sciences and Biotechnologies Sapienza University of RomeFaculty of Pharmacy and MedicineUrology Unit ICOTLatinaItaly Department of Urology European Institute of Oncology(IEO)IRCCSMilanItaly Department of Radiology D

Objective: To evaluate transperineal laser ablation (TPLA) with Echolaser® (Echolaser® TPLA, Elesta S.p.A., Calenzano, Italy) as a treatment for benign prostatic hyperplasia (BPH) and prostate cancer (PCa) using the Delphi consensus method.Methods: Italian and international experts on BPH and PCa participated in a collaborative consensus project. During two rounds, they expressed their opinions on Echolaser® TPLA for the treatment of BPH and PCa answering online questionnaires on indications, methodology, and potential complications of this technology. Level of agreement or disagreement to reach consensus was set at 75%. If the consensus was not achieved, questions were modified after each round. A final round was performed during an online meeting, in which results were discussed and finalized.Results: Thirty-two out of forty invited experts participated and consensus was reached on all topics. Agreement was achieved on recommending Echolaser® TPLA as a treatment of BPH in patients with ample range of prostate volume, from 80 mL (80%), comorbidities (100%), antiplatelet or anticoagulant treatment (96%), indwelling catheter (77%), and strong will of preserving ejaculatory function (100%). Majority of respondents agreed that Echolaser® TPLA is a potential option for the treatment of localized PCa (78%) and recommended it for low-risk PCa (90%). During the final round, experts concluded that it can be used for intermediate-risk PCa and it should be proposed as an effective alternative to radical prostatectomy for patients with strong will of avoiding urinary incontinence and sexual dysfunction. Almost all participants agreed that the transperineal approach of this organ-sparing technique is safer than transrectal and transurethral approaches typical of other techniques (97% of agreement among experts). Pre-procedural assessment, technical aspects, post-procedural catheterization, pharmacological therapy, and expected outcomes were discussed, leading to statements and recommendations.Conclusion: Ech

关键词： Transperineal laser ablation Prostatecancer Benignprostatic hyperplasia Delphi consensus

The Palmanova Cantonments： Conservation, Value-Enhancement and Transformation for an Integrated and Overall Regeneration

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 Civil Engineering and Architecture 2017年第6期11卷 559-570页

作者： Maria Paola Gatti giovanni russo Luca Zecchin Department of CiviL Environmental and Mechanical Engineering University of Trento Trento 38123 Italy

Preface to Focused Section on Efficient High-Order Time Discretization Methods for Partial 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 2021年第4期3卷 605-605页

作者： Sebastiano Boscarino Giuseppe Izzo Lorenzo Pareschi giovanni russo Chi-Wang Shu Universita degli Studi di Catania 95131 CataniaItaly Universita degli Studi di Napoli Federico II 80126 NaplesItaly Universita degli Studi di Ferrara 44121 FerraraItaly Brown University ProvidenceRI02912USA

During May 8-10,2019,the International Workshop on Efficient High-Order Time Discretization Methods for Partial Differential Equations took place in Villa Orlandi,Anacapri,Italy,a Congress Center of the University of Naples Federico II.About 40 senior researchers,young scholars,and Ph.D.students attended this workshop.The purpose of this event was to explore recent trends and directions in the area of time discretization for the numerical solution of evolutionary partial differential equations with particular application to high-order methods for hyperbolic systems with source and advection-diffusion-reaction equations,and with special emphasis on efficient time-stepping methods such as implicit-explicit(IMEX),semi-implicit and strong stability preserving(SSP)time discretization.The present focused section entitled“Efficient High-Order Time Discretization Methods for Partial Differential Equations”in Communications on Applied Mathematics and Computation(CAMC)consists of five regularly reviewed manuscripts,which were selected from submissions of works presented during the workshop.We thank all the authors of these contributions,and hope that the readers are interested in the topics,techniques and methods,and results of these papers.We also want to thank the CAMC journal editorial staff as well as all the referees for their contributions during the review and publication processes of this focused section.

关键词： thank hyperbolic preserving