Search results for " conductivity"

Thermal effects during adsorption of n-butane on a slilicalite-1 membrane. A non-equilibrium molecular dynamics study

2007

Abstract Non-equilibrium molecular dynamic (NEMD) simulations have been used to study the kinetics of adsorption of n-butane molecules in a silicalite membrane. We have chosen this simple well-known process to demonstrate that the process is characterized by two stages, both non-isothermal. In the first stage the large chemical driving force leads to a rapid uptake of n-butane in all the membrane and a simultaneous increase in the membrane temperature, explained by the large enthalpy of adsorption, Δ H = − 61.6 kJ / mol butane. A diffusion coefficient for transport across the external surface layer is calculated from the relaxation time; a value of 3.4 × 10 −9 m 2 / s is found. During the a…

Thermal Diffusion and Partial Molar Enthalpy Variations of n-Butane in Silicalite-1

2008

International audience; We report for the first time the heat of transfer and the Soret coefficient for n-butane in silicalite-1. The heat of transfer was typically 10 kJ/mol. The Soret coefficient was typically 0.006 K−1 at 360 K. Both varied with the temperature and the concentration. The thermal conductivity of the crystal with butane adsorbed was 1.46 ±0.07 W/Km. Literature values of the isosteric enthalpy of adsorption, the concentration at saturation, and the diffusion coefficients were reproduced. Non-equilibrium molecular dynamics simulations were used to find these results, and a modified heat exchange algorithm, Soft-HEX, was developed for the purpose. Enthalpies of butane were al…

Subsurface flow and large-scale lateral saturated soil hydraulic conductivity in a Mediterranean hillslope with contrasting land uses

2017

Abstract The lateral saturated hydraulic conductivity, Ks,l , is the soil property that mostly governs subsurface flow in hillslopes. Determinations of Ks,l at the hillslope scale are expected to yield valuable information for interpreting and modeling hydrological processes since soil heterogeneities are functionally averaged in this case. However, these data are rare since the experiments are quite difficult and costly. In this investigation, that was carried out in Sardinia (Italy), large-scale determinations of Ks,l were done in two adjacent hillslopes covered by a Mediterranean maquis and grass, respectively, with the following objectives: i) to evaluate the effect of land use change o…

An experimental investigation into the permeability and filter properties of pervious concrete for deep draining trenches

2018

The reduction of pore water pressures is one of the most effective measures that can be taken to stabilise landslides or to improve the stability conditions of marginally stable water-bearing slopes. To this end, draining trenches have been used long since. When deep trenches are needed, the usual conventional construction techniques fail and recourse must be made to secant piles or to adjacent vertical panels built by means of the methods well established for diaphragm walls. However, unbonded materials cannot be used, since the excavation of a panel adjacent to previously built ones will instabilise these latter. The problem can be solved using pervious concrete rather unbonded material. …

Design and Test of a Thermomagnetic Motor Using a Gadolinium Rotor

2013

This paper presents a Thermomagnetic Motor, whose design of the motor is based on a thermal-magnetic coupled dynamic model, which models its magnetic as well thermal properties (magnetic permeability and thermal conductivity). The thermal processes are supposed to be influenced by the thermal conductivity, the convection and the advection. An analytical expression of the generated torque, which links this quantity to the magnetic, thermal and geometrical parameters of the generated torque is given. A design of a machine, based on this theory is proposed and the related performances are numerically simulated. An experimental verification of the performances is reported.

The electromigration and diffusion of hydrogen in molybdenum

1990

Abstract The electromigration and diffusion of hydrogen atoms in molybdenum were investigated using the resistance method in the temperature range 293–773 K. The following dependence of the diffusion coefficient D and electrical mobility vE on temperature were obtained: D = (5.3 ± 1.53) × 10 −10 exp {− (0.8 ± 0.01) eV kT } { m 2 s −1 } v E = (1.24 ± 0.19) × 10 −8 exp {− (0.9 ± 0.01) eV kT }{ m 2 ( V s ) −1 } . The hydrogen migrates towards the cathode and the effective valency grows with temperature, fulfilling the relation Z eff = (1.42 ± 0.03) − (5.0 ± 0.2) × 10 −8 (Ω m ) ρ ; where ρ is the specific electric resistance.

Back Cover: Electrical Conductivity and Strong Luminescence in Copper Iodide Double Chains with Isonicotinato Derivatives (Chem. Eur. J. 48/2015)

2015

Misinterpretation caused by 3D effects on 2D Electrical Resistivity Tomography: tests on simple models

2018

Summary The aim of this work is to evaluate the effects of 2D inversion of electrical resistivity data when in presence on 3D structures by testing synthetic and experimental models. Several numerical simulations have been calculated for different resistivity models and 2D datasets were extracted to study and quantify the effects of 2D inversion on 3D structures. Results have been compared with field texts carried out in quarrying sites. The main tests here presented simulates prism-shaped cavities with a square vertical section of 1 × 1 size and a variable lateral extension d, from 1 to infinity (this latter being a 2D tunnel model). Inversion of predicted data show that 2D tomography does…

Dual atmosphere study of the K41X stainless steel for interconnect application in high temperature water vapour electrolysis

2015

Abstract High temperature water vapour electrolysis (HTE) is one of the most efficient technologies for mass hydrogen production. A major technical difficulty related to high temperature water vapour electrolysis is the development of interconnects working efficiently for a long period. Working temperature of 800 °C enables the use of metallic materials as interconnects. High temperature corrosion behaviour and electrical conductivity of a commercial stainless steel, K41X (AISI 441), were tested in HTE dual atmosphere (95%O 2 -5%H 2 0/10%H 2 -90%H 2 O) at 800 °C. The alloy exhibits a very good oxidation resistance compared to single atmosphere tests. However, a supplied electrical current s…

Influence of the three dimensionality of the HF electromagnetic field on resistivity variations in Si single crystals during FZ growth

2000

Abstract Three-dimensional numerical modelling is carried out to analyse the floating zone crystal growth with the needle-eye technique used for the production of high-quality silicon single crystals with large diameters ( ⩾100 mm ). Since the pancake inductor has only one turn, the EM field and the distribution of heat sources and EM forces are only roughly axisymmetric. The non-symmetry together with crystal rotation reflects itself on the hydrodynamic, thermal and dopant concentration fields in the molten zone and causes variations of resistivity in the grown single crystal, which are known as the so-called rotational striations. The non-symmetric high-frequency electromagnetic field of …