3,469 research outputs found
La declaración unilateral de independencia de Kosovo a la luz de la Opinión Consultiva de la Corte Internacional de Justicia, de 22 de julio de 2010 y de las declaraciones, opiniones individuales y disidentes a la misma
The Opinion of the International Court of Justice on the unilateral declaration of independence of Kosovo is an example of what the Court should not do. Saying only that international law does not prohibit declarations of independence and refusing to answer the matters related to this claim, the Court's opinion adopts a vacuum of legal terms and irresponsible
Una aproximación práctica para el diseño de un proceso de reciclado de polímeros mediante disolución
La cantidad de residuos plásticos producidos en los últimos años se ha visto incrementada debido a la variedad de usos y las buenas propiedades que estos presentan. Por este motivo, es necesario ofrecer soluciones que permitan un reciclaje adecuado a cada tipo de residuo, siguiendo con las normativas vigentes. Entre las alternativas desarrolladas se encuentran el reciclado mecánico, químico y la incineración, sin embargo, estos metodos cuentan con determinados inconvenientes que dificultan su aplicación. Para solventar estos, se propone el tratamiento de los residuos mediante disolución, lo que implica la seleccion adecuada del mejor disolvente, con el objetivo de tratar la máxima cantidad de plástico posible. Esta selección se desarrolla siguiendo una serie de modelos teóricos que permiten el cálculo del parametro de solubilidad (d), y su interpretación a traves de distintos metodos gráficos que permiten seleccionar de manera sencilla los disolventes más adecuados. Por último, tambíen se muestran estrategias de cálculo para conocer las condiciones de operación que vienen definidas por una concentración y temperatura críticas, que limitan la región en la que la disolución permanece estable, y por tanto, es posible realizar el proceso de reciclado
Exact relativistic models of thin disks around static black holes in a magnetic field
The exact superposition of a central static black hole with surrounding thin
disk in presence of a magnetic field is investigated. We consider two models of
disk, one of infinite extension based on a Kuzmin-Chazy-Curzon metric and other
finite based on the first Morgan-Morgan disk. We also analyze a simple model of
active galactic nuclei consisting of black hole, a Kuzmin-Chazy-Curzon disk and
two rods representing jets, in presence of magnetic field. To explain the
stability of the disks we consider the matter of the disk made of two
pressureless streams of counterrotating charged particles (counterrotating
model) moving along electrogeodesic. Using the Rayleigh criterion we derivate
for circular orbits the stability conditions of the particles of the streams.
The influence of the magnetic field on the matter properties of the disk and on
its stability are also analyzed.Comment: 17 pages, 14 figures. arXiv admin note: text overlap with
arXiv:gr-qc/0409109 by other author
Quantum Interference in Single Molecule Electronic Systems
We present a general analytical formula and an ab initio study of quantum
interference in multi-branch molecules. Ab initio calculations are used to
investigate quantum interference in a benzene-1,2-dithiolate (BDT) molecule
sandwiched between gold electrodes and through oligoynes of various lengths. We
show that when a point charge is located in the plane of a BDT molecule and its
position varied, the electrical conductance exhibits a clear interference
effect, whereas when the charge approaches a BDT molecule along a line normal
to the plane of the molecule and passing through the centre of the phenyl ring,
interference effects are negligible. In the case of olygoynes, quantum
interference leads to the appearance of a critical energy , at which the
electron transmission coefficient of chains with even or odd numbers of
atoms is independent of length. To illustrate the underlying physics, we derive
a general analytical formula for electron transport through multi-branch
structures and demonstrate the versatility of the formula by comparing it with
the above ab-initio simulations. We also employ the analytical formula to
investigate the current inside the molecule and demonstrate that large counter
currents can occur within a ring-like molecule such as BDT, when the point
charge is located in the plane of the molecule. The formula can be used to
describe quantum interference and Fano resonances in structures with branches
containing arbitrary elastic scattering regions connected to nodal sites.Comment: 12 pages, 11 figure
Representative elementary area for multifractal analysis of soil porosity using entropy dimension
International audienceThe notion of representative elementary area (REA) developed to address heterogeneity and scale problems in quantitative soil pedology comes from the notion of representative elementary volume of fluid dynamics in porous media. The REA allows the identification of the minimum area of a soil block section that is required to represent the pedofeature of interest based on its distribution in soil space. In this paper eight samples were imaged with two different techniques: the confocal microscope and the conventional film camera. These techniques provided information about pore sizes between 3.62 ?m and 161.98 ?m, and between 39.72 ?m and 1776.34 ?m, respectively. Sixteen of the resulting digital images were then analyzed to investigate the representative elementary area of the multifractal patterns of the spatial distribution of voids related to the micro and macroporosity by means of the entropy dimension. Our results permit the location of the REA region over the domain of the microstructures rendered by the analysis of the microscope images. They also suggest that this region seemingly spans scales of the macrostructures as revealed by the analysis of the camera pictures
Predictive Fault Diagnosis for Ship Photovoltaic Modules Systems Applications
[EN] In this paper, an application for the management and supervision by predictive fault diagnosis (PFD) of solar power generation systems is developed through a National Marine Electronics Association (NMEA) 2000 smart sensor network. Here, the NMEA 2000 network sensor devices for measuring and supervising the parameters inherent to solar power generation and renewable energy supply are applied. The importance of renewable power generation systems in ships is discussed, as well as the causes of photovoltaic modules (PVMs) aging due to superimposed causes of degradation, which is a natural and inexorable phenomenon that affects photovoltaic installations in a special way. In ships, PVMs are doubly exposed to inclement weather (solar radiation, cold, rain, dust, humidity, snow, wind, electrical storms, etc.), pollution, and a particularly aggressive environment in terms of corrosion. PFD techniques for the real-world installation and safe navigation of PVMs are discussed. A specific method based on the online analysis of the time-series data of random and seasonal I¿V parameters is proposed for the comparative trend analyses of solar power generation. The objective is to apply PFD using as predictor symptom parameter (PS) the generated power decrease in affected PVMs. This PFD method allows early fault detection and isolation, whose appearance precedes by an adequate margin of maneuver, from the point of view of maintenance tasks applications. This early detection can stop the cumulative degradation phenomenon that causes the development of the most frequent and dangerous failure modes of solar modules, such as hot-spots. It is concluded that these failure modes can be conveniently diagnosed by performing comparative trend analyses of the measured power parameters by NMEA sensors.García Moreno, E.; Quiles Cucarella, E.; Zotovic Stanisic, R.; Gutiérrez, SC. (2022). Predictive Fault Diagnosis for Ship Photovoltaic Modules Systems Applications. Sensors. 22(6):1-21. https://doi.org/10.3390/s2206217512122
Anti-inflammatory activity of
The anti-inflammatory activity of the chloroform, methanol and aqueous extracts of Wigandia urens and Acalypha alopecuroides were investigated on carrageenan-induced paw edema at doses of 400 mg/kg. The three extracts of W. urens, and the aqueous extract of A. alopecuroides caused significantinhibition of the edema (58.1±6.5% and 63.5±5.4%, respectively). Indomethacin was used as positive control (8 mg/kg), and inhibited edema by 66.3±5.2%. The methanol extract of W. urens and the aqueous extract of A. alopecuroides, at doses of 200 mg/kg, inhibited pellet implantation-induced granuloma formation by 69.4±6.5 and 70.6±6.6%, respectively. These levels of inhibition are higher than those exhibited by naproxen at doses of 50 mg/kg (46.1±7.1%). Both extracts showed activity on adjuvantinduced arthritis in rats, with the best effect being observed after 96 h (82.2±4.6 and 80.6±7.3%, respectively)
Drag reduction on a blunt body by self-adaption of rear flexibly hinged flaps
We study the aerodynamics of a blunt-based body with rear flexibly-hinged rigid flaps,
subject to a turbulent flow of Reynolds number Re = 12000, under aligned and cross
flow conditions with yaw angle β = 0◦ and β = 4◦. To that aim, different values of
the equivalent torsional stiffness are considered, to cover the range of reduced velocity
U∗ = (0, 3.48] in water tank experiments. The effect of the angular deflection of
plates on the drag and near wake flow is analyzed, experimentally and numerically.
The results show that, in the range of U∗ herein considered, the plates undergo an
inwards quasi-static, self-adaptive deflection, which is symmetric for yaw angles β = 0◦
and asymmetric for β = 4◦. In particular, the plates feature small mean deformation
angles for values of U∗ < 1, whereas a sharp and monotonic increase of such deflection
occurs for U∗ > 1, i.e. for lower values of the hinge’s stiffness, with an asymptotic
trend towards the larger values of U∗. A critical value of reduced velocity of U∗ ≃ 0.96
is obtained as the instability threshold above which plates depart from their initial
equilibrium position. The progressive streamlining of the trailing edge translates into
significant reductions of the associated mean drag coefficients. Thus, reductions close
to 19% with respect to reference static plates configurations are obtained for the most
flexible case of U∗ = 3.48 for both β = 0◦ and β = 4◦. A close inspection of the
near wake reveals that the inwards progressive mean displacement of the plates yields
a reduction in the recirculation bubble size. A symmetric evolution of the recirculating
bubble is observed for β = 0◦, whereas the bubble becomes asymmetric for β = 4◦,
with a larger leeward clockwise vortex. In both cases, the drag coefficient is shown
to vary linearly with the global aspect ratio of the recirculating bubble. The analysis
of the numerical results shows that the reduced extension of the recirculating bubble
significantly alters the formation length and intensity of the eddies size and associated
pressure. It is observed that despite the local pressure decrease in the vortices shed from
the trailing edges, the plates self adaption reduces their size and prevents the eddies
from entering the cavity, thus, creating a dead flow region with a consequent pressure
increase at the body base.Junta de Andalucia FEDER-UJA 1262764Universidad de JaenEuropean CommissionSpanish MCIN/AEI PDC2021-121288-I00European Union Next Generation EU/PRT
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