Search results for "saturation"
showing 10 items of 478 documents
Coarsening of Antiferromagnetic Domains in Multilayers: The Key Role of Magnetocrystalline Anisotropy
2002
The domain structure of an antiferromagnetic superlattice is studied. Synchrotron Mössbauer and polarized neutron reflectometric maps show micrometer-size primary domain formation as the external field decreases from saturation to remanence. A secondary domain state consisting mainly of at least 1 order of magnitude larger domains is created when a small field along the layer magnetizations induces a bulk-spin-flop transition. The domain-size distribution is reproducibly dependent on the magnetic prehistory. The condition for domain coarsening is shown to be the equilibrium of the external field energy with the anisotropy energy.
Non-linear inductor modelling for a DC/DC buck converter
2017
The paper is focused on the modelling of an inductor to exploit its non-linear behaviour in the roll-off region when it is employed in a DC/DC converter. The model is set up on the basis of experimental data measured in operating conditions, which are fitted to a polynomial curve describing the inductance variations. The analysis of the buck converter, performed by including the proposed model, is validated by experimental tests.
Analysis of multipactor RF breakdown in a waveguide containing a transversely magnetized ferrite
2016
In this paper, the multipactor RF breakdown in a parallel-plate waveguide partially filled with a ferrite slab magnetized normal to the metallic plates is studied. An external magnetic field is applied along the vertical direction between the plates in order to magnetize the ferrite. Numerical simulations using an in-house 3-D code are carried out to obtain the multipactor RF voltage threshold in this kind of structures. The presented results show that the multipactor RF voltage threshold at certain frequencies becomes considerably lower than for the corresponding classical metallic parallel-plate waveguide with the same vacuum gap
Coupled hydro-mechanical analysis of compacted bentonite behaviour during hydration
2021
Abstract This study analyses the response of compacted bentonites upon hydration based on a coupled hydro-mechanical elasto-plastic framework. As an alternative to multi-porosity interpretation, the framework was selected based on the experimental evidence of adsorbed water behaviour in bentonites and the volumetric response at saturated states, apparently independent of its initial state. Based on these premises, a water retention model was formulated using an explicit distinction between adsorbed water and free water, enabling the postulation of the water properties and behaviour depending on its state. In order to effectively account for the transition between unsaturated to saturated st…
Application of silicon-based camera for measurement of non-homogeneous thermal field on realistic specimen surface
2019
Abstract The high-cost low-resolution infrared cameras operating in middle infrared spectral ranges are widely used to detect the thermal fields. In this study, a low-cost high-resolution silicon-based sensor camera operating in near infrared spectral ranges is used to perform the observation of the thermal fields on the realistic steel specimen surface. In near-infrared spectral ranges, a small temperature variation led to a large modification in the sensor illumination, inducing acquired images with over saturation or poor dynamic range of gray levels. To address this problem, an algorithm was used to precisely adjust the exposure time to acquire images with constant gray level whatever t…
Power losses comparison between Silicon Carbide and Silicon devices for an isolated DC-DC converter
2021
In recent years, new efficient power devices have been implemented. Silicon Carbide has replaced silicon as regards the production and the utilization of many devices, such as MOSFETs, diodes, IGBTs and many others. SiC devices are characterized by a low reverse recovery charge, high carrier saturation velocity, by which it is possible to work at high frequency, and high breakdown voltage. Thanks to the great thermal conductivity and the wide bandgap, these devices can operate at high temperature and reach high voltages and currents. What is important to stress is the fact that power losses in SiC devices are lower than the silicon ones. These are the reasons why these devices are utilized …
Pulsed Direct liquid Injection ALD of TiO2 Films Using Titanium Tetraisopropoxide Precursor
2013
Abstract TiO 2 thin films are grown by pulsed direct liquid injection atomic layer deposition with rapid thermal heating using titanium tetraisopropoxide and water vapor as precursors. The ALD growth rate is constant in the saturation zone range 35-47 ms at the temperature deposition of 280 °C. The TiO 2 growth rate of 0.018 nm/cycle was achieved in a self-limited ALD mode. SEM and AFM analysis showed the as-deposited films have a smooth surface with a low roughness. XPS analysis exhibited the stoichiometry of TiO 2 in the homogenous depth composition.
On the hydro-mechanical behaviour of a lime-treated embankment during wetting and drying cycles
2018
Abstract The paper presents some experimental results obtained on samples extracted from a full-scale embankment obtained by compacting a lime-treated clayey soil. A comprehensive test programme was carried out in order to highlight the improvement of mechanical behaviour induced by lime treatment as well as to assess the durability of the improved material, which may be affected by severe seasonal wetting and drying cycles. Direct shear tests, triaxial compression tests, swelling potential measurement and oedometric tests were performed on samples cured in controlled environmental conditions for at least 18 months. Wetting and drying cycles were applied in a very wide range of suction valu…
Kinetics and isotherm of fibronectin adsorption to three-dimensional porous chitosan scaffolds explored by125I-radiolabelling
2013
In this study, 125I-radiolabelling was explored to follow the kinetics and isotherm of fibronectin (FN) adsorption to porous polymeric scaffolds, as well as to assess the elution and exchangeability of pre-adsorbed FN following incubation in serum-containing culture medium. Chitosan (CH) porous scaffolds with two different degrees of acetylation (DA 4% and 15%) were incubated in FN solutions with concentrations ranging from 5 to 50 µg/mL. The kinetic and isotherm of FN adsorption to CH were successfully followed using 125I-FN as a tracer molecule. While on DA 4% the levels of adsorbed FN increased linearly with FN solution concentration, on DA 15% a saturation plateau was attained, and FN a…
Nonmonotone Saturation Profiles for Hydrostatic Equilibrium in Homogeneous Porous Media
2012
Nonmonotonic saturation profiles (saturation overshoot) occur as travelling waves in gravity driven fingering. They seem important for preferential flow mechanisms and have found much attention recently. Here, we predict them even for hydrostatic equilibrium when all velocities vanish. We suggest that hysteresis suffices to explain the effect. Recently, the observation of nonmonotonicity of traveling wave solutions for saturation profiles during constant-flux infiltration experiments has highlighted the shortcomings of the traditional, seventy year old mathematical model for immiscible displacement in porous media. Several recent modifications have been proposed to explain these observation…