Search results for "thermal [radiation]"
showing 10 items of 1167 documents
Determination of transport and kinetic properties in self-propagating high-temperature synthesis
2007
International audience; Exothermic reactions in solid powders are analyzed using the usual macroscopic modeling based on the heat transfer equation coupled to an Arrhenius type of dynamics. This problem have important applications in the synthesis of intermetallics and ceramic materials which occur when a high temperature reaction wave propagates throughout the system. Understanding the mechanism of such processes are thus crucial in mastering real laboratory experiments. We first analyze the model, both theoretically and numerically, for a set of representative parameters. We then use traditional data analyses procedures to estimate from the temperature profiles the same set of representat…
An experimental study of dynamic behaviour of graphite polycarbonatediol polyurethane composites for protective coatings
2013
Segmented polycarbonatediol polyurethane (PUPH) has been synthesized and modified with different amounts of graphite conductive filler (from 0 to 50 wt%). Thermal and dynamical thermal analysis of the composites clearly indicates changes in the polyurethane relaxations upon addition of graphite. Broadband dielectric spectroscopy has been used to study the dielectric properties of the (PUPH) and one composite in the frequency range from 10−2 to 107 Hz and in the temperature window of −140 to 170 ◦C. Relaxation processes associated with different molecular motions and conductivity phenomena (Maxwell–Wagner–Sillars and electrode polarization) are discussed and related to the graphite content
Magma extrusion during the Ubinas 2013-2014 eruptive crisis based on satellite thermal imaging (MIROVA) and ground-based monitoring
2015
After 3 years of mild gases emissions, the Ubinas volcano entered in a new eruptive phase on September 2nd, 2013. The MIROVA system (a space-based volcanic hot-spot detection system), allowed us to detect in near real time the thermal emissions associated with the eruption and provided early evidence of magma extrusion within the deep summit crater. By combining IR data with plume height, sulfur emissions, hot spring temperatures and seismic activity, we interpret the thermal output detected over Ubinas in terms of extrusion rates associated to the eruption. We suggest that the 2013–2014 eruptive crisis can be subdivided into three main phases: (i) shallow magma intrusion inside the edifice…
Methods for Determining the Thermal Transfer in Phase-Changing Materials (PCMs).
2020
A very important issue that needs to be solved as simply and correctly as possible is how to establish the thermal performance of phase-changing materials (PCM). The undertaken researches have analyzed the values of the thermal performances of the PCM taking into account the method of finite elements and the experimental research, respectively, based on a modern measurement system that was designed and implemented. Butyl stearate which has been encapsulated through complex coacervation in polymethyl methacrylate has been used as a PCM. Samples were made containing 10%, 20%, 30% and 40% PCM, respectively, within their structure. The research has established that at both the hot plate and the…
Mapping snow density through thermal inertia observations
2023
Snow, as a fundamental reservoir of freshwater, is a crucial natural resource. Specifically, knowledge of snow density spatial and temporal variability could improve modelling of snow water equivalent, which is relevant for managing freshwater resources in context of ongoing climate change. The possibility of estimating snow density from remote sensing has great potential, considering the availability of satellite data and their ability to generate efficient monitoring systems from space. In this study, we present an innovative method that combines meteorological parameters, satellite data and field snow measurements to estimate thermal inertia of snow and snow density at a catchment scale.…
Mass transfer in nonisothermal ferrocolloids under the effect of a magnetic field
1999
Abstract The paper presents a review of newest experimental results on particle thermal diffusion in hydrocarbon based ferrofluids. The measurements are performed using a vertical thermal diffusion column, the Soret coefficient is evaluated from particle separation curves employing a simple column theory which accounts for thermal convection in the vertical channel forced by a concentration buoyancy force arising during the thermophoretic transfer of heavy particles. High positive values of the Soret coefficient of lyophilized Fe 3 O 4 and Mn x Zn 1− x Fe 2 O 4 particles in surfacted tetradecane based colloids are measured. Experiments confirm the theoretically predicted anisotropy of parti…
Thermoosmotic transfer of sterically stabilized ferrofluid particles in non-isothermal capillary porous layer
2005
Experiments on thermodiffusive transfer of ferrofluid nanoparticles in capillary porous layer are presented. The layer consists of a number of capillary filter sheets pressed between two plates of different temperatures. Steady profiles of particle concentration are detected after the experiment from magnetization of each filter sheet. It is shown that particle separation in porous layer is remarkably influenced by thermoosmotic forces. The observed effect is different for colloids of various surfactants and of various carrier liquids.
Transport properties of an ionic magnetic colloid: experimental study of increasing the ionic strength
2002
Abstract The phase separation of an ionic magnetic colloid in zero magnetic field by increasing the ionic strength is well known [Universite Paris VI, France, 1987; J. Colloid Interface Sci. 132 (1989) 1]. The present work deals with investigation of an ionic ferrofluid by increasing the ionic strength in the range of 0–0.14 mol/l, being safely below the threshold value at which the effect of phase separation occurs. By the optical grid setup [Fourth International conference PAMIR, France, 2000], the main transport properties of a ferrofluid, i.e. translational mass diffusion and thermal diffusion (Soret) coefficients, are measured. The obtained results show a strong dependence of mass diff…
{CoIII2DyIII2} single molecule magnet with two resolved thermal activated magnetization relaxation pathways at zero field
2014
The new complex [CoIII2DyIII 2(OMe)2(teaH)2(Piv)6] in the {CoIII2DyIII2} family, shows two well resolved thermal activated magnetization relaxation pathways under AC experiments in zero DC field. Fitted crystal field parameters suggest that the origin of these two pathways relies on two different excited mJ sub-levels. Fil: Funes, Víctor Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; Argentina …
Convergence of the finite volume method for a conductive-radiative heat transfer problem
2013
We show that the finite volume method rigorously converges to the solution of a conductive-radiative heat transfer problem with nonlocal and nonlinear boundary conditions. To get this result, we start by proving existence of solutions for a finite volume discretization of the original problem. Then, by obtaining uniform boundedness of discrete solutions and their discrete gradients with respect to mesh size, we finally get L 2type convergence of discrete solutions.