检索结果-南通市图书馆

LINeAR STIeLTJeS eQUATION WITH GeNeRALIZeD RIeMANN INTeGRAL AND eXISTeNCe OF ReGULATeD SOLUTIONS

在线全文

学校读者我要写书评

暂无评论

Acta Mathematicae Applicatae Sinica 2001年第4期17卷 526-531页

作者： L.BARBANTI instituto de matemática e estatística Departamento de Matemática Universidade de São Paulo São Paulo Brasil

In this work we establish an existence theorem of regulated solutions for a class of Stieltjes equations which involve generalized fuemann kind of integrals. The general method spplied consists in considering the continuous-time Stieltjes equation as limit of discrete processes. This approach will prove fruitful in the study of the controllability of Stieltjes systems, because it will be possible to get properties on the continuous time equation by transferring properties of the discrete ones.

关键词： existence of regulated solutions integral equations approximation scheme in time for Stieltjes equations

Parameter estimation in Manneville–Pomeau processes

在线全文

学校读者我要写书评

暂无评论

Probability, Uncertainty and Quantitative Risk 2023年第2期8卷 213-234页

作者： Barbara P.Olbermann Sílvia R.C.Lopes Artur O.Lopes Faculdade de matemática-PUCRS 90650-002 Porto AlegreRSBrazil instituto de matemática e estatística-ufrgs 91500-900 Porto AlegreRSBrazil

In this paper,we study a class of stochastic processes{X_(t)}t∈N,where X_(t)=φ■T_(s)^(t)(X_(0))is obtained from the iterations of the transformation T_(s),invariant for an ergodic probabilityμ_(s)on[0,1]and a certain constant by partial functionφ:[0,1]→*** consider here the family of transformations T_(s):[0,1]→[0,1]indexed by a parameters>0,known as the Manneville–Pomeau family of *** autocorrelation function of the resulting process decays hyperbolically(or polynomially)and we obtain efficient methods to estimate the parameter s from a finite time *** a consequence,we also estimate the rate of convergence of the autocorrelation decay of these *** compare different estimation methods based on the periodogram function,the smoothed periodogram function,the variance of the partial sum,and the wavelet *** obtain our results we analyzed the properties of the spectral density function and the associated Fourier series.

关键词： Manneville–Pomeau maps Long and not so long dependence estimation Autocorrelation decay Spectral density function

Impact of Zika virus non-structural protein mutations on hippocampal damage

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

Neural Regeneration Research 2025年第8期20卷 2307-2308页

作者： Larissa M.G.Cassiano Roney S.Coimbra Neurogenômica/Imunopatologia Instituto RenéRachouFiocruzBelo HorizonteBrazil departamento de Bioquímica e Imunologia Instituto de Ciências BiológicasUniversidade Federal de Minas GeraisBelo HorizonteBrazil

The Zika virus(ZIKV),a member of the Flaviviridae family,attracted worldwide attention for its connection to severe neurological effects,notably microcephaly in newborns,first reported during the 2015 epidemic in ***,its impact goes beyond fetal and neonatal abnormalities,also affecting the central nervous system(CNS)in both children and adults,leading to enduring cognitive and behavioral impairments.

关键词： damage fetal neonatal

eXISTeNCe OF SOLUTIONS OF nTH-ORdeR NONLINeAR DIFFeReNCe eQUATIONS WITH GeNeRAL BOUNDARY CONDITIONS

在线全文

学校读者我要写书评

暂无评论

Acta Mathematica Scientia 2020年第1期40卷 226-236页

作者： Alberto CABADA Nikolay DIMITROV departamento de estatística Análise Matemática e OptimizaciónInstituto de MatemáticasFacultade de MatemáticasUniversidade de Santiago de CompostelaSantiago de CompostelaGaliciaSpain depatment of Mathematics University of RuseRuse 7000Bulgaria

The aim of this paper is to prove the existence of one or multiple solutions of nonlinear difference equations coupled to a general set of boundary *** to do this,we construct a discrete operator whose fixed points coincide with the solutions of the problem we are looking ***,we introduce a strong positiveness condition on the related Green's function that allows us to construct suitable cones where to apply adequate fixed point *** we have the general existence result,we deduce,as a particular case,the existence of solutions of a second order difference equation with nonlocal perturbed Dirichlet conditions.

关键词： difference equation multiplicity of solutions Green's function positive solutions parameter dependence

Interpolation of Ideal Measures by Abstract K and J Spaces

在线全文

学校读者我要写书评

暂无评论

Acta Mathematica Sinica,english Series 2007年第8期23卷 1357-1374页

作者： Luz M.FeRNNdeZ-CABReRA Antón MARTíNeZ Sección departamental de matemática Aplicada Escuela de EstadísticaUniversidad Complutense de Madrid28040 MadridSpain departamento de matemática Aplicada I E.T.S.Ingenieros IndustrialesUniversidad de Vigo36200

We work with the abstract K and J interpolation method generated by a sequence lattice Г. We investigate the deviation of an interpolated operator from a given operator ideal by establishing formulae for the ideal measure of the interpolated operator in terms of the ideal measures of restrictions of the operator. Formulae are given in terms of the norms of the shift operators on Г.

关键词： real interpolation ideal measures operator ideals shift operators

Maximum mass of magnetic white dwarfs

在线全文

学校读者我要写书评

暂无评论

Research in Astronomy and Astrophysics 2015年第10期15卷 1735-1741页

作者： Daryel Manreza Paret Jorge ernesto Horvath Aurora Pérez Martínez departamento de Fisica General Facultad de FísicaUniversidad de la Habana instituto de Astronomia Geofisica e Ciencias Atmosfericas USP instituto de Cibernética Matemática y Física(ICIMAF)

We revisit the problem of the maximum masses of magnetized white dwarfs （WDs）. The impact of a strong magnetic field on the structure equations is addressed. The pressures become anisotropic due to the presence of the magnetic field and split into parallel and perpendicular components. We first construct stable solutions of the Tolman-Oppenheimer-Volkoff equations for parallel pressures and find that physical solutions vanish for the perpendicular pressure whenB ≥ 10^13 G. This fact estab- lishes an upper bound for a magnetic field and the stability of the configurations in the （quasi） spherical approximation. Our findings also indicate that it is not possible to obtain stable magnetized WDs with super-Chandrasekhar masses because the val- ues of the magnetic field needed for them are higher than this bound. To proceed into the anisotropic regime, we can apply results for structure equations appropriate for a cylindrical metric with anisotropic pressures that were derived in our previous work. From the solutions of the structure equations in cylindrical symmetry we have con- firmed the same bound for B- 10^13 G, since beyond this value no physical solutions are possible. Our tentative conclusion is that massive WDs with masses well beyond the Chandrasekhar limit do not constitute stable solutions and should not exist.

关键词： magnetic fields -- white dwarfs -- equation of state

ASYMPTOTIC RAReFACTION WAVeS FOR BALANCe LAWS WITH STIFF SOURCeS

在线全文

学校读者我要写书评

暂无评论

Acta Mathematica Scientia 2009年第6期29卷 1613-1628页

作者： W. Lambert D. Marchesin 1-instituto Nacional de matemtica Pura e Aplicada Estrada Dona Castorina 11022460-320 Rio de Janeiro RJ Brazil instituto de matemtica Pura e Aplicada Estrada Dona Castorina 11022460-320 Rio de Janeiro RJ Brazil

We study the long time formation of rarefaction waves appearing in balance laws by means of singular perturbation methods. The balance laws are non standard because they contain a variable u that appears only in the flux terms. We present a concrete example occurring in flow of steam, nitrogen and water in porous media and an abstract example for a class of systems of three equations. In the concrete example the zero-order equations resulting from the expansion yield a type of conservation law system called compositional model in Petroleum engineering. In this work we show how compositional models originate from physically more fundamental systems of balance laws. Under appropriate conditions, we prove that certain solutions of the system of balance laws decay with time to rarefaction wave solutions in the compositional model originating from the system of balance laws.

关键词： balance laws asymptotic expansion rarefaction waves compositional models

Noether conserved quantities and Lie point symmetries of difference Lagrange-Maxwell equations and lattices

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2009年第7期18卷 2634-2641页

作者：傅景礼聂宁明黄健飞 Jiménez Salvador 唐贻发 Vzquez Luis 赵维加 Institute of Mathematical Physics Zhejiang Sci-Tech University State Key Laboratory of Scientific and engineering Computing ICMSECAcademy of Mathematics and Systems ScienceChinese Academy of Sciences department of Mathematics Qingdao University departamento de matema'tica Aplicada TTII E.T.S.I.Telecomunicacio'nUniversidad Polit'ecnica de Madrid28040-MadridSpain departamento de matemática Aplicada Facultad de MatemáticasInstituto de Matemática Interdisciplinar(IMI)Universidad Complutense de Madrid28040-MadridSpain departamento de matemática Aplicada Facultad de InformáticaInstituto de Matemática Interdisciplinar(IMI)Universidad Complutense de Madrid28040-MadridSpain

This paper presents a method to find Noether-type conserved quantities and Lie point symmetries for discrete mechanico-electrical dynamical systems,which leave invuriant the set of solutions of the corresponding difference scheme. This approach makes it possible to devise techniques for solving the Lagrange Maxwell equations in differences which correspond to mechanico-electrical systems,by adapting existing differential *** particular,it obtains a new systematic method to determine both the one-parameter Lie groups and the discrete Noether conserved quantities of Lie point symmetries for mechanico-electrical *** an application,it obtains the Lie point symmetries and the conserved quantities for the difference equation of a model that represents a capacitor microphone.

关键词： Lagrange Maxwell equation Lie point symmetry discrete mechanico-electrical system conserved quantity

Obstruction Theory and Coincidences in Positive Codimension

在线全文

学校读者我要写书评

暂无评论

Acta Mathematica Sinica,english Series 2006年第5期22卷 1591-1602页

作者： Daciberg GONCALVeS Jerzy JeZIeRSKI Peter WONG departamento de matemática-instituto de matemdtica e estatística-Universidade de Sǎo Paulo Caixa Postal 66.281-CEP 05311-970 Sǎo Paulo-SP Brasil department of Mathematics University of Agriculture Nowoursynowska 166 02766 Warszawa Poland department of Mathematics Bates College Lewiston ME 04240 USA

Let f, g ： X→Y be two maps between closed manifolds with dim X ≥ dim Y = n ≥ 3. We study the primary obstruction on（f, g） to deforming f and g to be coincidence free on the n-th skeleton of X. We give examples f... 详细信息

关键词： Nielsen number Reidemeister number coincidence theory obstruction theory