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Photoluminescence characteristics of soft PZT 53/47 ceramic doped at A and/or B sites

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Journal of Advanced Ceramics 2018年第2期7卷 109-116页

作者： M.D.DURRUTHY-RODRíGUEZ J.J.GERVACiO-ARCiNiEGA M.HERNáNdeZ-GARCíA J.M.YánEZ-LiMóN Universidad Nacional Evangélica departamento de Física aplicada Instituto de CibernéticaMatemáticay FísicaCITMA Catedrático CONACYT-Facultad de Ciencias Físico matemáticas Benemérita Universidad Autónoma de Puebla CiNVESTAV-Unidad Querétaro del iPN Libramiento Norponiente 2000Fracc.Real de Juriquilla

This study presents the photoluminescence characteristics of the PZT 53/47 system doped at A and/or B sites, with Nb(PZTN), La(PLZT), and Nb–La(PLZTN) in the concentration range from 0.2 to 1.0 molar fraction. The intensity of the emission bands of the system PZTN is two orders higher than the intensity of the emission bands of the systems PLZT and PLZTN, and these emission bands are located at 1.73 eV(718 nm), 2.56 eV(485 nm), and 2.93 eV(424 nm). The origin of the luminescence in these systems is associated with lead and oxygen vacancies produced during the sintering process. The results from X-ray diffraction(XRD) show a mixture of rhombohedral and tetragonal phases. The system PZTN shows a higher tetragonal phase concentration, while PLZT and PLZTN systems show a higher rhombohedral phase concentration. The cell volume shows an increase with dopant concentration only in the case of the PLZTN system. The band gap energy shows a small variation in the PZTN and PLZTN cases around 3.0 eV, a close value to the band gap energy of the pure PZT 53/47 sample. The system PLZT shows an increasing behavior until 4.41 eV for the higher dopant concentration.

关键词： photoluminescence PZT ceramics band structure X-ray diffraction(XRD)

Maximum mass of magnetic white dwarfs

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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

Regular Global Attractors of Type Ⅲ Thermoelastic Extensible Beams

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Chinese Annals of Mathematics,Series B 2010年第5期31卷 619-630页

作者： Michele COTi ZELATi Vittorino PATA Ramon QUiNTANiLLA Mathematics department Indiana UniversityRawles Hall Dipartimento di matematica "F. Brioschi" Politecnico di Milano matemtica aplicada 2 ETSEiAT-UPC Terrassa

For β∈ R,the authors consider the evolution system in the unknown variables u and ααttu+αxxxxu+αxxtα-(β+αxu L22)αxxu=f,αttα-αxxα-αxxtα-αxxtu=0 describing the dynamics of type iii thermoelastic extensible beams,where the dissipation is entirely contributed by the second equation ruling the evolution of the thermal displacement α.Under natural boundary conditions,the existence of the global attractor of optimal regularity for the related dynamical system acting on the phase space of weak energy solutions is established.

关键词：弹性梁热弹性 Ⅲ型自然边界条件进化系统动态扩展 iii 热位移

Trivial and Simple Spectrum for SL(d,R) Cocycles with Free Base and Fiber Dynamics

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Acta Mathematica Sinica,English Series 2015年第7期31卷 1113-1122页

作者： Mrio BESSA Paulo VARANDAS departamento de matemtica Universidade da Beira InteriorRua Marquês d'vila e Bolama6201-001 CovilhPortugal departamento de matemtica Universidade Federal da BahiaAv.Ademar de Barros s/n40170-110 SalvadorBrazil

Let ACD（M, SL（d,R）） denote the pairs （f, A） so that f∈ A C Diff^1（M） is a C^1-Anosov transitive diffeomorphisms and A is an SL（d,R） cocycle dominated with respect to f. We prove that open and densely in ACD（M, SL（d,R））, in appropriate topologies, the pair （f,A） has simple spectrum with respect to the unique maximal entropy measure μf. Then, we prove prevalence of trivial spectrum near the dynamical cocycle of an area-preserving map and also for generic cocycles in AUtLeb（M） × LP（M, SL（d, R））.

关键词： Linear cocycles Lyapunov exponents Anosov diffeomorphisms topological conjugacy,maximal entropy measures

Anisotropic stellar structure equations for magnetized strange stars

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Research in Astronomy and Astrophysics 2015年第7期15卷 975-985页

作者： Daryel Manreza Paret Jorge Ernesto Horvath Aurora Pérez Mart'nez departamento de F'sica General Facultad de F'sica Universidad de la Habana instituto de Astronomia Geofisica e Ciencias Atmosfericas USP instituto de Cibernética Matemática y Física (ICIMAF)

The fact that a fermion system in an external magnetic field breaks the spherical symmetry suggests that its intrinsic geometry is axisymmetric rather than spherical. in this work we analyze the impact of anisotropic pressures, due to the presence of a magnetic field, in the structure equations of a magnetized quark *** assume a cylindrical metric and an anisotropic energy momentum tensor for the source. We found that there is a maximum magnetic field that a strange star can sustain, closely related to the violation of the virial relations.

关键词： magnetic fields -- stars: neutron -- equation of state

Coincidence Wecken Property for Nilmanifolds

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Acta Mathematica Sinica,English Series 2019年第2期35卷 239-244页

作者： Daciberg GON?ALVES Peter WONG departamento de matemática-iME-Universidade de S?o Paulo Rua do Mat?o department of Mathematics Bates College

Let f, g: X → Y be maps from a compact infra-nilmanifold X to a compact nilmanifold Y with dim X ≥ dim Y. in this note, we show that a certain Wecken type property holds, i.e., if the Nielsen number N(f, g) vanishes then f and g are deformable to be coincidence free. We also show that if X is a connected finite complex X and the Reidemeister coincidence number R(f, g) = ∞ then f ～ f' so that C(f', g) = {x ∈ X | f'(x) = g(x)} is empty.

关键词： Nielsen coincidence theory nilmanifolds

ASYMPTOTiC LiMiTS AND STABiLiZATiON FOR THE 1D NONLiNEAR MiNDLiN-TiMOSHENKO SYSTEM

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Journal of Systems Science & Complexity 2010年第3期23卷 414-430页

作者： F.D.ARARUNA P.BRAZ E SiLVA E.ZUAZUA departamento de matemática Universidade Federal da Paraíba departamento ikerbasque Research Professor Basque Center for Applied Mathematics(BCAM)

这份报纸出现怎么所谓的 von K ? 潶 ??

关键词：奇异极限系统非线性一维稳定剪切弹性模量阻尼机制四阶色散

Eigenvectors of Permutation Matrices

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Advances in Pure Mathematics 2015年第7期5卷 390-394页

作者： M. isabel Garca-Planas M. Dolors Magret departament de matemàtica aplicada i Universitat Politècnica de Catalunya Barcelona Spain

The spectral properties of special matrices have been widely studied, because of their applications. We focus on permutation matrices over a finite field and, more concretely, we compute the minimal annihilating polynomial, and a set of linearly independent eigenvectors from the decomposition in disjoint cycles of the permutation naturally associated to the matrix.

关键词： Permutation Matrices Eigenvalues Eigenvectors

The tensor embedding for a Grothendieck cosmos

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Science China Mathematics 2023年第11期66卷 2471-2494页

作者： Henrik Holm Sinem Odabasi department of Mathematical Sciences University of CopenhagenCopenhagen 02100Denmark instituto de Ciencias Físicas y matemáticas Universidad Austral de ChileValdivia 5090000Chile

While the Yoneda embedding and its generalizations have been studied extensively in the literature,the so-called tensor embedding has only received a little *** this paper,we study the tensor embedding for closed symmetric monoidal categories and show how it is connected to the notion of geometrically purity,which has recently been investigated in the works of Enochs et al.(2016)and Estrada et al.(2017).More precisely,for a Grothendieck cosmos,i.e.,a bicomplete Grothendieck category V with a closed symmetric monoidal structure,we prove that the geometrically pure exact category(V,ε■)has enough relative injectives;in fact,every object has a geometrically pure injective *** also show that for some regular cardinalλ,the tensor embedding yields an exact equivalence between(V,ε■)and the category ofλ-cocontinuous V-functors from Presλ(V)to V,where the former is the full V-subcategory ofλ-presentable objects in *** many cases of interest,λcan be chosen to be■0 and the tensor embedding identifies the geometrically pure injective objects in V with the(categorically)injective objects in the abelian category of V-functors from fp(V)to *** we explain,the developed theory applies,e.g.,to the category Ch(R)of chain complexes of modules over a commutative ring R and to the category Qcoh(X)of quasi-coherent sheaves over a(suitably nice)scheme X.

关键词： enriched functor exact category (pre)envelope (pure)injective object purity symmetric monoidal category tensor embedding Yoneda embedding