检索结果-南通市图书馆

Low-dimensional quadratic relative character varieties for the projective line minus three points Dedicated to my friend Gang Xiao

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Science China Mathematics 2024年

作者： Carlos Simpson cnrs Laboratoire JA Dieudonne Parc Valrose Université C?te d'Azur

We show that relative character varieties having a fixed dimension d > 0, for irreducible orthogonal or symplectic local systems of rank r on P1-{0, 1, ∞}, are isomorphic via Katz's middle convolution to ones with a ...

关键词：

A global analysis of the introduction pathways and characteristics associated with non-native fish species introduction, establishment, and impacts

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Ecological Processes 2024年第2期13卷 16-31页

作者： Camille Bernery Céline Bellard Franck Courchamp Sébastien Brosse Boris Leroy cnrs Agro Paris Tech Ecologie Systématique Evolution Université Paris-Saclay Unité Biologie des Organismes et Ecosystèmes Aquatiques (BOREA UMR 8067) Muséum National d’Histoire Naturelle Sorbonne Universités Université de Caen Normandie Université des Antilles CNRS IRD laboratoire évolution & Diversité Biologique (EDB UMR5174) Université Paul Sabatier-Toulouse 3 CNRS IRD UPS

Background The invasion success of introduced freshwater fishes is influenced by many factors, including ecological, species, and socioeconomic characteristics. Most studies that document the importance of these characteristics are conducted at local scales and/or focus on a single step of the invasion process. In this study, we aim to determine the species characteristics, ecological characteristics, and socioeconomic characteristics of non-native freshwater fish invasions. Our assessment was done at the global scale and considers all three steps of the invasion(i.e., introduction, establishment, and impact). For this purpose, we applied generalized linear models to 20 variables collected for 307 non-native species and modeled them as a function of ecological characteristics(i.e., environmental features), species traits(i.e., functional and morphological), and socioeconomic characteristics(i.e., human use and introduction pathways). We considered the number of countries in which each species was introduced, established, or had ecological impacts as a proxy of invasion step success. We also explored the specifics of species introduced through the aquaculture and the ornamental fish trade *** We found that non-native freshwater fishes with broad diets, high parental care, and multiple introduction pathways are the most widely introduced and established worldwide. The number of countries with impacts reported was best explained by the type of introduction pathway(i.e., aquaculture or fisheries). Moreover, among non-native species introduced through aquaculture, those belonging to Cypriniformes and having broad diets were the most widely introduced and established species. In contrast, the species introduced through the ornamental fish trade pathway belonged to various taxonomic orders but were mainly native to tropical *** Considering several types of factors is important when analyzing the invasion success of freshwater fish and disentang

关键词： Aquaculture Ecology Exotic Freshwater fish Introduction pathway Invasion step Morphology Ornamental fish trade Socioeconomic Trait

A level line of the Gaussian free field with measure-valued boundary conditions

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Science China Mathematics 2024年第2期67卷 367-404页

作者： Titus Lupu Hao Wu laboratoire de Probabilités Statistique et ModélisationSorbonne Universitéand UniversitéParis CitéCNRSParis F-75005France Yau Mathematical Sciences Center Tsinghua UniversityBeijing 100084China

In this article, we construct samples of Schramm-Loewner-evolution-like curves out of samples ofthe conformal loop ensemble and Poisson point processes of Brownian excursions. We show that the laws of thesecurves depend continuously on the intensity measure of the Brownian excursions. Using such a construction ofcurves, we extend the notion of level lines of the Gaussian free field to the case where the boundary conditionis measure-valued.

关键词： Schramm-Loewner evolution conformal loop ensemble Brownian excursion Gaussian free field

维普期刊数据库

Deciphering dynamic surface of PtRu alloy nanocatalysts to revisit their synergistic effects during the electrooxidation

在线全文

学校读者我要写书评

暂无评论

Science China Chemistry 2024年第7期67卷 2224-2233页

作者： Xiao-Chong Li Bo Wang Zhou Yu Qiang Wan Ju-Fang Zheng Emmanuel Maisonhaute Xiao-Shun Zhou Ya-Hao Wang Key Laboratory of the Ministry of Education for Advanced Catalysis Materials Institute of Physical ChemistryZhejiang Normal UniversityJinhua 321004China laboratoire Interface et Systèmes Electrochimiques CNRS UMR 8235Sorbonne UniversitéF-75252 Paris cedex 5France

Correlating dynamic structural transformation of catalysts with the surface intermediate species under operating conditions is critical for updating the understanding of structure–performance ***,we probe the electrochemical potentialdependent surface structures and adsorbed intermediates on PtRu binary alloy nanocatalysts to revisit its synergistic mechanisms for CO electrooxidation enhanced ***-situ spectral characteristics by using modified shell-isolated nanoparticle-enhanced Raman spectroscopy,show that in acidic solution,when the potential is positively scanned from 0.1 V to 1.5 V relative to reversible hydrogen electrode(RHE),the surface of the alloy catalyst evolves from metallic PtRu to adsorbed oxygen gradually covering and accumulating on Ru sites(denoted as PtRuO_(x),x≤2),forming segregated RuO_(2),and finally forming a threedimensional oxide layer(denoted as 3D PtRuO_(4)).Moreover,molecular evidence associated with periodic density functional theory calculations reveals that electronic effects promote ruthenium to become more oxidizable and *** particular,we found here that ^(*)O and ^(*)OH at surface RuO_(x) sites are highly efficient CO oxidation active species in comparison to the same entities adsorbed on metallic Ru *** work sheds light on the complex surface dynamic process of practical Pt-based binary nanocatalysts and improves the understanding of synergistic mechanism for the development of fuel cell devices.

关键词： in-situ Raman spectroscopy surface evolution bifunctional mechanism PtRu electrooxidation

维普期刊数据库

Purity-dependent Lorenz number,electron hydrodynamics and electron-phonon coupling in WTe_(2)

在线全文

学校读者我要写书评

暂无评论

Science China(Physics,Mechanics & Astronomy) 2024年第8期67卷 153-158页

作者： Wei Xie Feng Yang Liangcai Xu Xiaokang Li Zengwei Zhu Kamran Behnia Wuhan National High Magnetic Field Center and School of Physics Huazhong University of Science and TechnologyWuhan 430074China laboratoire de Physique et d’Etude des Matériaux(ESPCI-cnrs-Sorbonne Université)PSL University Paris 75005France

We present a study of electrical and thermal transport in Weyl semimetal WTe_(2)down to 0.3 *** Wiedemann-Franz law holds below 2 K and a downward deviation starts *** deviation is more pronounced in cleaner samples,as expected in the hydrodynamic picture of electronic transport,where a fraction of electron-electron collisions conserve *** are the dominant heat carriers and their mean-free-path does not display a Knudsen *** is presumably a consequence of weak anharmonicity,as indicated by the temperature dependence of the specific *** momentum exchange between phonons and electrons leads to quantum oscillations of the phononic thermal ***-Grüneisen picture of electron-phonon scattering breaks down at low temperature when Umklapp ph-ph collisions cease to be a sink for electronic flow of *** with semi-metallic Sb shows that normal ph-ph collisions are amplified by *** both semimetals,at cryogenic temperature,e-ph collisions degrade the phononic flow of energy but not the electronic flow of momentum.

关键词： thermal conductivity Wiedemann-Franz law electron hydrodynamics electron-phonon coupling

维普期刊数据库

同方期刊数据库

High-Order Two-Scale Asymptotic Paradigm for the Elastodynamic Homogenization of Periodic Composites

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Solida Sinica 2024年第1期37卷 124-138页

作者： Wei-Zhi Luo Mu He Liang Xia Qi-Chang He State Key Laboratory of Intelligent Manufacturing Equipment and Technology Huazhong University of Science and TechnologyWuhan 430074China laboratoire Modélisation et Simulation Multi-Echelle MSME UMR 8208 CNRSUniversite Gustave Eiffel77454 Marne-la-ValléeFrance

The classical two-scale asymptotic paradigm provides macroscopic and microscopic analyses for the elastodynamic homogenization of periodic composites based on the spatial or/and temporal variable,which offers an approximate framework for the asymptotic homogenization analysis of the motion ***,in this framework,the growing complexity of the homogenization formulation gradually becomes an obstacle as the asymptotic order *** such a context,a compact,fast,and accurate asymptotic paradigm is *** work reviews the high-order spatial two-scale asymptotic paradigm with the effective displacement field representation and optimizes the implementation by symmetrizing the tensor to be ***,the modified implementation gets rid of the excessive memory consumption required for computing the high-order tensor,which is demonstrated by representative one-and two-dimensional *** numerical results show that(1)the contrast of the material parameters between media in composites directly affects the convergence rate of the asymptotic results for the homogenization of periodic composites,(2)the convergence error of the asymptotic results mainly comes from the truncation error of the modified asymptotic homogenized motion equation,and(3)the excessive norm of the normalized wavenumber vector in the two-dimensional inclusion case may lead to a non-convergence of the asymptotic results.

关键词： Composites Homogenization Asymptotic analysis Dynamics Dispersion

Guillaume Broux-Quemerais,Sarah Kaakai, Anis Matoussi,Wissal Sabbagh

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Probability, Uncertainty and Quantitative Risk 2024年第2期9卷 149-180页

作者： Guillaume Broux-Quemerais Sarah Kaakarl Anis Matoussi Wissal Sabbagh laboratoire Manceau de Mathematiques&FR cnrs No 2962 Institut du Risque et de I'AssuranceLeMansUniversityFrance Centre de Mathématiques Appliquees(CMAP) CNRSEcole polytechniqueInstitut Polytechnique de Paris91120 PalaiseauFrance

In this paper,we present a probabilistic numerical method for a class of forward utilities in a stochastic factor *** this purpose,we use the representation of forward utilities using the ergodic Backward Stochastic Differential Equations(eBSDEs)introduced by Liang and Zariphopoulou in[27].We establish a connection between the solution of the ergodic BSDE and the solution of an associated BSDE with random terminal time T,defined as the hitting time of the positive recurrent stochastic *** viewpoint based on BSDEs with random horizon yields a new characterization of the ergodic cost^which is a part of the solution of the *** particular,for a certain class of eBSDEs with quadratic generator,the Cole-Hopf transformation leads to a semi-explicit representation of the solution as well as a new expression of the ergodic cost>.The latter can be estimated with Monte Carlo *** also propose two new deep learning numerical schemes for ***,we present numerical results for different examples of eBSDEs and forward utilities together with the associated investment strategies.

关键词： Deep leaming scheme Forward utilities Ergodic BSDEs Markovian solution Deep learning algorithm

The inhomogeneous incompressible Hall-MHD system with only bounded density

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Science China Mathematics 2024年

作者： Jin Tan Lan Zhang laboratoire de Math′ematiques AGM UMR CNRS 8088 Cergy Paris Universit′e Center for Mathematical Sciences and Department of Mathematics Wuhan University of Technology

This paper is dedicated to the global-in-time existence and uniqueness issues of solutions for the inhomogeneous incompressible Hall-magnetohydrodynamics(MHD) system with merely bounded density. In a three-dimensional case, assuming that the initial density is a small perturbation of a positive constant in the L∞norm, we prove global well-posedness for small initial velocity and magnetic fields in critical Besov spaces. Next, we consider the so-called 21/2D flows for the inhomogeneous Hall-MHD system(that is 3D flows independent of the vertical variable) and establish the global existence of strong solutions by only assuming that the initial magnetic field is small in critical spaces and the initial density is bounded and bounded away from zero. In particular, those solutions allow piecewise constant density with jumps so that a mixture of fluids can be considered. Compared with inhomogeneous incompressible Navier-Stokes equations, the new difficulties of proving these results come from the additional so-called Hall term, which endows the magnetic equation with a quasi-linear character. In order to overcome them, we reformulate the system by taking advantage of the curl form of the magnetic equation and develop some new maximal regularity estimates for the Stokes system with just bounded coefficients.

关键词：

The algebra of symmetric tensors on smooth projective varieties In Memory of Professor Gang Xiao

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Science China Mathematics 2024年

作者： Arnaud Beauville Jie Liu cnrs Laboratoire J.-A.Dieudonné Université C?te d'Azur Institute of Mathematics Academy of Mathematics and Systems ScienceChinese Academy of Sciences

In this paper, we discuss the C-algebra H0(X, S~·TX) for a smooth complex projective variety *** compute it in some simple examples, and give a sharp bound on its Krull dimension. Then we propose a conjectural charac...

关键词：