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Electrostatic and Magnetostatic Forces That Arise from Electrostatic and Magnetostatic Pressures

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Journal of Electromagnetic Analysis and Applications 2019年第3期11卷 25-40页

作者： josé-Luis Jiménez-Ramírez Ignacio Campos-Flores josé-antonio-eduardo roa-neri Departamento de Física Facultad de Ciencias Universidad Nacional Autónoma de México CDMX México área de Física Teórica y Materia Condensada División de Ciencias Básicas e Ingeniería Universidad Autónoma Metropolitana Unidad Azcapotzalco México D. F. México

With the insight provided by a balance equation of electromagnetic momentum, we compare the force on a dielectric slab inside a capacitor with the force on a magnetizable rod inside a solenoid. We conclude that these forces are not exactly analogous, as usually thought. We present a device that is a proper analogy of the case of a dielectric slab inside a capacitor. Our analysis shows the significance of the electrostatic and magnetostatic pressures to the understanding of these effects and shows the conceptual differences between both cases.

关键词： Polarizable Electric and Magnetic Media Electric and Magnetic Pressures Electromagnetic Force Densities Macroscopic Maxwell Equations Balance Equations of Electromagnetic Momentum

Balance Equations of Electromagnetic Angular Momentum

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Journal of Electromagnetic Analysis and Applications 2017年第12期9卷 203-217页

作者： Ignacio Campos-Flores josé Luis Jiménez-Ramírez josé antonio eduardo roa-neri Departamento de Física Facultad de Ciencias Universidad Nacional Autónoma de México Mexico City México área de Física Teórica y Materia Condensada División de Ciencias Básicas e Ingeniería Universidad Autónoma Metropolitana Unidad Azcapotzalco Mexico City México

We give theoretical foundation to torque densities proposed in the past, like the one used by Beth to study experimentally the action of circularly polarized radiation on a birefringent material, or that proposed by Mansuripur to resolve a seeming paradox concerning the Lorentz force law and relativity. Our results provide new insights into electromagnetic theory, since they provide a unified and general treatment of the balance of lineal and angular momentum that permits a better assessment of some torques. Thus in this work we extend the derivations we have made of balance equations for electromagnetic linear momentum to balance equations for electromagnetic angular momentum. These balance equations are derived from the macroscopic Maxwell equations by means of vector and tensor identities and from the different ways in which these equations are written in terms of fields E, D, B, and H, as well as polarizations P, and M. Therefore these balance equations are as sound as the macroscopic Maxwell equations, with the limitations of the constitutive relations.

关键词： Balance Equations Foundations of Electrodynamics Electromagnetic Angular Momentum Macroscopic Maxwell Equations Abraham-Minkowski Controversy

How Does Arise the Force on a Dielectric Slab in a Parallel Plate Capacitor?

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Journal of Electromagnetic Analysis and Applications 2018年第7期10卷 131-142页

作者： Ignacio Campos-Flores josé-Luis Jiménez-Ramírez josé-antonio-eduardo roa-neri Departamento de Física Facultad de Ciencias Universidad Nacional Autónoma de México Mexico City Mexico rea de Física Teórica y Materia Condensada División de Ciencias Básicas e Ingeniería Universidad Autónoma Metropolitana Unidad Azcapotzalco Mexico City Mexico

We address the problem of the force exerted on a dielectric slab partially introduced into a charged parallel plate capacitor. This elementary problem is usually solved calculating this force as the gradient of an energy and attributing its origin to the action of the fringing field outside the capacitor on the dipoles of the dielectric slab. By applying Maxwell’s theory of electromagnetic stresses, we show that this force acts at the interface dielectric-vacuum and originates from the action of these stresses. This approach permits to obtain the force as a volume integration of a force density, or as a surface integral of a stress tensor. This force density and the stress tensor are part of a momentum balance equation derived from Maxwell’s equations.

关键词： Classical Electromagnetism Maxwell Equations Electrostatics Maxwell Balance Equation Maxwell Stress Tensor

Induced Dipoles in Electromagnetic Media in Motion

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Journal of Electromagnetic Analysis and Applications 2018年第11期10卷 185-192页

作者： josé-antonio-eduardo roa-neri josé-Luis Jiménez-Ramírez Ignacio Campos-Flores área de Física Teórica y Materia Condensada División de Ciencias Básicas e Ingeniería Universidad Autónoma Metropolitana Unidad Azcapotzalco México D. F. México Departamento de Física Facultad de Ciencias Universidad Nacional Autónoma de México México D. F. México

We present a non-relativistic approach to the equivalent polarization Peq=(1/c2)v×Meq, that appears in a magnetized medium in motion. We apply an analogous method to that used by Panofsky and Phillips to calculate the symmetric effect, the equivalent magnetization that appears in a polarized dielectric in motion, Meq=P×v,?This method is based on a particular expression of Maxwell’s equations and the application of the convective derivative. These authors argue, however, that the equivalent polarization can be obtained only with a relativistic approach. We show that with the same method, but with a different and equivalent expression of Maxwell’s equations, this effect can also be calculated. In this way both effects can be considered relativistic effects to first order in v/c.

关键词： Moving Media Polarized Dielectric Macroscopic Maxwell Equations Induction of Magnetic Dipoles

Thermal and salinity effects on locomotor performance of Thoropa taophora tadpoles(Anura,Cycloramphidae)

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Integrative Zoology 2020年第1期15卷 40-54页

作者： antonio C.GALLO Cinthia ABRASILEIRO Fábio Cury DE BARROS joséeduardo DE CARVALHO Department of Ecology and Evolutionary Biology Federal University of São PauloDiademaSão PauloBrazil

It is well known that environmental temperature influences several biological functions of ectotherms,notably in *** high permeability of anuran skin,associated with the effect of elevated environmental temperature,potentiates the dehydration process and this combination may restrict locomotor ***pa taophora is an endemic species from the Atlantic Rainforest whose tadpoles are semiterrestrial and predominantly diurnal,and are found in rocky seashores where they are exposed to sea spray and high *** this study we investigated how temperature and salinity conditions affect the locomotor performance in Thoropa taophora *** also assessed how different osmotic concentrations affect the activity of the metabolic pathways that support muscle *** measured the sprint speed of tadpoles of various sizes at different temperatures and salinities in the *** also measured the activity of the enzymes pyruvate kinase(PK),lactate dehydrogenase(LDH)and citrate synthase(CS)in different temperatures and osmotic concentrations,and calculated the thermal sensitivity and the activity constants for each *** results showed that,in general,sprint speed decreased with increasing temperature and ***,whereas the effect of increased salinity was similar in smaller and larger tadpoles,increased temperature had a higher negative impact on sprint speed of larger tadpoles,thus indicating low thermal sensitivity of small *** and LDH thermal sensitivities and LDH constant of activity decreased as the osmolality *** conclusion,the locomotor capacity of tadpoles was decreased by temperature and salinity,which may be related to a decrease in anaerobic metabolism both in terms of sensitivity and total energy turnover through enzymatic *** discuss the ecological consequences,including the potential impacts on predator escape behavior promoted by changes in metabolism and locomotor performance

关键词： amphibians energy metabolism enzyme activity sprint speed

Effect of rhenium on the microstructure and mechanical behavior of Fe–2.25Cr–1.6W–0.25V-0.1C bainitic steels

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Journal of Materials Science & Technology 2017年第12期33卷 1487-1493页

作者： josé antonio Jiménez Manuel Carsí Oscar antonio Ruano Department of Physical Metallurgy Centro Nacional de lnvestigaciones MetalurgicasC.S.I.CAvda.Gregorio del Amo 828040 MadridSpain

A new ferritic creep resistant steel has been developed by eliminating Nb and adding 1.5 mass % Re to a ferritic steel grade T/P23 with the aim of enhancing its mechanical properties at high *** ingots of both steels, new grade and ASTM T/P 23, were hot rolled at 900℃ and then submitted to a thermal treatment consisting of solubilization at 1050℃ and tempering at 700℃. Tempered bainitic microstructures obtained contain second phases reinforcing carbide particles, mainly M_6C and M_（23）C_6 at the boundaries of both, prior austenite grains and bainitic ferrite laths, as well as MC within the grains. Mechanical properties at temperatures ranging from 540 to 600℃ were studied by strain-ratechange tests in compression at strain rates between 10^（-7） and 10^（-4）s^（-1）. These tests showed high stress exponents（n ≥ 20） and activation energies（Q ≈ 400 k J/mol） for both alloys, which were associated with a dislocation movement mechanism with a strong interaction between dislocations and precipitates. On the other hand, a creep exponent of 5 was derived for the stress dependence of minimum creep rate from conventional-type creep tests at 600℃. Although this stress exponent is usually related to a dislocation climb controlled creep mechanism, remarkable microstructural degradation observed with increasing creep time makes difficult to elucidate the true deformation mechanism controlling creep.

关键词： Creep resistant steel T/P23 Thermal treatment Tempered bainite High temperature mechanical properties Creep

A Proof of Wedderburn＇s Theorem

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Algebra Colloquium 2015年第4期22卷 603-606页

作者： josé antonio Cuenca Mira Departamento de álgebra Geometría y Topología Facultad de Ciencias Universidad de Málaga 29071 Málaga Spain

In this note we first introduce the finite weak Herstein condition, which is a property that holds for every finite field. For a field F satisfying the finite weak Herstein condition, we then characterize whether all the finite-dimensional division F-algebras are commutative. This gives an alternate proof of Wedderburn＇s Theorem.

关键词： division algebra finite-dimensional algebra finite field Galois extension

Gravitational waves from compact objects

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Research in Astronomy and Astrophysics 2010年第11期10卷 1071-1099页

作者： josé antonio de Freitas Pacheco University of Nice-Sophia Antipolis Observatoire de la Cote d'Azur Laboratoire Cassiopée-UMR 6202 BP 4229-F606304-Nice Cedex 4-France

Large ground-based laser beam interferometers are presently in operation both in the USA （LIGO） and in Europe （VIRGO） and potential sources that might be detected by these instruments are revisited. The present generation of detectors does not have a sensitivity high enough to probe a significant volume of the universe and, consequently, predicted event rates are very low. The planned advanced generation of interferometers will probably be able to detect, for the first time, a gravitational sig- nal. Advanced LIGO and EGO instruments are expected to detect few （some）： binary coalescences consisting of either two neutron stars, two black holes or a neutron star and a black hole. In space, the sensitivity of the planned LISA spacecraft constellation will allow the detection of the gravitational signals, even within a ＂pessimistic＂ range of possible signals, produced during the capture of compact objects by supermassive black holes, at a rate of a few tens per year.

关键词： gravitational waves -- neutron stars -- black holes

Evaluation of the effectiveness of horizontal subsurface flow constructed wetlands for different media

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Journal of Environmental Sciences 2010年第6期22卷 820-825页

作者： antonio Albuquerque josé Oliveira Sabrina Semitela Leonor Amaral Department of Civil Engineering and Architecture and C-MADE University of Beira Interior Municipality of Penamacor Department of Sciences and Environmental Engineering Faculty of Sciences and TechnologyNew University of Lisbon

Two media bed （gravel and Filtralite NR） were tested in a mesocosm to evaluate the removal of organic matter （as chemical oxygen demand （COD））, ammonia （NH4-N）, nitrite, nitrate and solid matter （as total suspended solids （TSS）） for a synthetic wastewater （acetate-based） and a domestic wastewater. The use of Filtralite allowed average removal rates （6--16.8 g COD/（m^2·day）, 0.8-1.1 g NH4-N/（m^2·day） and 3.1 g TSS/（m^2·day）） and removal efficiencies （65%-93%, 57%-85% and 78% for COD, NH4-N and TSS, respectively）, higher than that observed in the experiments with gravel. The applied loads of COD, ammonia, nitrate and TSS seem to influence the respective removal rates but only for the treatment of domestic wastewater with nigher correlation coefficients for Filtralite. Regardless the type of media bed and the type of wastewater, nitrate was completely removed for nitrogen loading rates up to 1.3 g NO3-N/（m^2·day）. There was no evidence of the influence of nitrate loads on the removal of organic matter.

关键词： media bed constructed wetlands pollutants removal rates