Search results for "Partial"
showing 10 items of 1477 documents
Structural and conductivity study of the proton conductor BaCe(0.9−x)ZrxY0.1O(3−ı) at intermediate temperatures.
2009
International audience; The perovskite BaCe(0.9−x)ZrxY0.1O(3−ı) is prepared by solid-state reaction at 1400 ◦C and sintering at 1700 ◦C. It is characterised using X-ray diffraction, Raman spectroscopy and electrical measurements. A distortion fromthe cubic structure at roomtemperature is noticeable in the Raman spectra for 0.2 < x < 0.8, but not in the X-ray diffraction patterns. This work points out the rhombohedral nature of this distortion. Phase transitions are studied up to 600 ◦C. The direct current conductivity is measured as a function of oxygen partial pressure, and at a water vapour partial pressure of 0.015 atm. The total conductivity is resolved into an ionic and a p-type compon…
High-Speed Machines: Typologies, Standards, and Operation under PWM Supply
2018
This paper presents an overview of the most recent state of the art in the field of high-speed electric machines fed through high-frequency converters. This type of systems is rapidly wide spreading in aeronautical and automotive applications, as well as microturbines. Each typology has its own advantages and downsides, which are analytically presented in this paper. Some types of high-speed electric machines require high-frequency voltage supply, highly stressing the dielectric materials of the winding insulation system. For this reason, in high-speed electric drives, premature failure may occur and a reduction of the total system reliability has been observed in the past years. Such issue…
CLONIDINE, A PARTIAL AGONIST OF THE HISTAMINERGIC H2 RECEPTORS?
1978
Detrás de las palabras: usos políticos del concepto de imparcialidad y su función en la construcción de la historia de América en la Ilustración espa…
2018
En tiempos de renovado debate sobre el presentismo y la objetividad de los historiadores, pretendo indagar en los usos ideológicos y las funciones políticas que desempeñó el concepto de imparcialidad en la Ilustración española, su relación con la escritura de la historia y, más particularmente, con la conquista de América. A partir de diversos textos impresos de finales del s. XVIII e inicios del s. XIX —apologías, elogios, diccionarios y otros textos literarios— y adoptando una metodología que aúna la historia cultural y de los conceptos, me detendré en cómo las élites culturales dieciochescas atribuyeron al concepto un significado positivo y necesario para construir los discursos sobre lo…
La primera aproximación de Hollywood a la Guerra Civil española: <em>The Last Train From Madrid (1937)</em> / First Approach of Hollywood…
2017
La Guerra Civil española fue un tema prohibido de forma tácita en el Hollywood regulado por la autocensura de la Oficina Hays y la PCA. Como consecuencia, las productoras cinematográficas norteamericanas sólo realizaron tres films sobre la contienda mientras se desarrolló (1936-1939). Este artículo analiza el contenido histórico y discurso ideológico de The Last Train From Madrid (James Hogan, 1937), la primera aproximación de Hollywood a la guerra de España. Se trata de un film menor, apenas estudiado, que sigue sin estar editado comercialmente. Sin embargo, posee gran relevancia en lo que atañe a la visión inaugural que se ofreció al público estadounidense sobre la beligerancia española e…
Post-Double Hopf Bifurcation Dynamics and Adaptive Synchronization of a Hyperchaotic System
2012
In this paper a four-dimensional hyperchaotic system with only one equilibrium is considered and its double Hopf bifurcations are investigated. The general post-bifurcation and stability analysis are carried out using the normal form of the system obtained via the method of multiple scales. The dynamics of the orbits predicted through the normal form comprises possible regimes of periodic solutions, two-period tori, and three-period tori in parameter space. Moreover, we show how the hyperchaotic synchronization of this system can be realized via an adaptive control scheme. Numerical simulations are included to show the effectiveness of the designed control.
Turing Instability and Pattern Formation for the Lengyel–Epstein System with Nonlinear Diffusion
2014
In this work we study the effect of density dependent nonlinear diffusion on pattern formation in the Lengyel---Epstein system. Via the linear stability analysis we determine both the Turing and the Hopf instability boundaries and we show how nonlinear diffusion intensifies the tendency to pattern formation; in particular, unlike the case of classical linear diffusion, the Turing instability can occur even when diffusion of the inhibitor is significantly slower than activator's one. In the Turing pattern region we perform the WNL multiple scales analysis to derive the equations for the amplitude of the stationary pattern, both in the supercritical and in the subcritical case. Moreover, we c…
A year in the life of an aluminous metapelite xenolith—The role of heating rates, reaction overstep, H2O retention and melt loss
2011
Abstract Xenoliths of aluminous metapelite within the Platreef magmatic rocks of the Bushveld Complex, South Africa, are mineralogically and texturally zoned, with coarse-grained margins rich in acicular corundum, spinel and feldspar and cores rich in finer-grained aluminosilicate and cordierite. Xenoliths exhibiting remarkably similar features occur within other intrusions, suggesting a common origin. Using a single 3 m wide xenolith as a case study, a model is proposed to explain their petrogenesis. Mineral equilibria calculations in the NCKFMASHTO system show that the thermal stability of the solid phases, in particular corundum, is highly sensitive to the quantity of H 2 O retained in t…
The Interdependence of Respiratory Gas Values and pH as a Function of Base Excess in Human Blood at 37°C
1973
The accurate estimation of the transport function of human blood for respiratory gases as well as the respiratory gas exchange in human body requires detailed knowledge of the respiratory gas partial pressures and the acid-base status in the blood. Because there is an interdependence between the different respiratory gas parameters described as Bohr and Haldane effect (3,4), it is possible to obtain a general picture of the whole transport system, if these interrelations are known.
Interannual persistence effects in vegetation dynamics of semi-arid Africa
2005
[1] Over 15 years of Normalized Difference Vegetation Index (NDVI) data from the Advanced Very High Resolution Radiometers (AVHRR) are used to study the response of vegetation activity to rainfall in three semi-arid regions of Africa. The relationships between annual NDVI and annual precipitation (PPT) time series are examined using statistical approaches (simple and partial correlations, linear multiple regressions). It appears that annual NDVI highly depends on PPT of the concurrent year and the previous year. An analysis of particularly dry and wet years enables to better diagnose two distinct responses of vegetation activity to rainfall. The “recovery” effect represents the difficulty o…