Search results for " Conduction"

Heat Conduction Problem for Double-Layered Ball

2014

Heat conduction models for double layered spherical sample are developed. Parabolic (classic, based on Fourier’s Law) and hyperbolic (based on Modified Fourier’s Law) heat conduction equations are used to describe processes in the sample during Intensive Quenching. Solution and numerical results are obtained for 1D model using Conservative Averaging method and transforming the original problem for a sphere to a new problem for a slab, with non classic boundary condition. Models include boundary conditions of third kind and non-linear BC case. Numerical results are presented for several relaxation time and initial heat flux values.

Convergence of nociceptive and non-nociceptive inputs onto spinal reflex pathways to the tibialis anterior muscle in humans

1998

The interaction of low-threshold mechanoreceptive and nociceptive inputs onto spinal neurones probably plays a major role in the pathophysiology of the clinical sign of allodynia. This phenomenon was investigated by modulation of the early component of the flexor reflex (FR) in the tibialis anterior (TA) muscle, elicited by electrical stimulation of the medial plantar nerve at the sole of the foot, by homotopically applied painful heat in humans. This early reflex with an electrical threshold of 2.7-fold the detection threshold and a mean afferent conduction velocity of 49 m s-1 is a non-nociceptive FR. When applying conditioning painful heat (46 degrees C) to the sole of the foot this refl…

Mhd-Modeling of the Propagation of a Coronal Mass Ejection

2005

Hydrodynamic modeling of the propagation of a density perturbation launched upwards in the solar corona has been shown to explain some features of a Coronal Mass Ejection (CME) observed in detail with the SoHO/UVCS, but left open the questions of the evidence of thermal insulation of the CME and of its large expansion factor. We investigate whether the interaction with the coronal magnetic field is able to explain these aspects, by performing magnetohydrodynamic simulations. We solve the ideal MHD equations for a fully ionized compressible plasma with different assumptions on the ambient magnetic field, using the FLASH code. We include the effect of the directional thermal conduction. Preli…

QT interval heterogeneities induced through local epicardial warming/cooling. An experimental study

2014

[EN] ntroduction and objectives Abnormal QT interval durations and dispersions have been associated with increased risk of ventricular arrhythmias. The present study examines the possible arrhythmogenic effect of inducing QT interval variations through local epicardial cooling and warming. Methods In 10 isolated rabbit hearts, the temperatures of epicardial regions of the left ventricle were modified in a stepwise manner (from 22 °C to 42 °C) with simultaneous electrogram recording in these regions and in others of the same ventricle. QT and activation-recovery intervals were determined during sinus rhythm, whereas conduction velocity and ventricular arrhythmia induction were determined dur…

Quantum walk on the line through potential barriers

2015

Quantum walks are well-known for their ballistic dispersion, traveling $\Theta(t)$ away in $t$ steps, which is quadratically faster than a classical random walk's diffusive spreading. In physical implementations of the walk, however, the particle may need to tunnel through a potential barrier to hop, and a naive calculation suggests this could eliminate the ballistic transport. We show by explicit calculation, however, that such a loss does not occur. Rather, the $\Theta(t)$ dispersion is retained, with only the coefficient changing, which additionally gives a way to detect and quantify the hopping errors in experiments.

Radiation effects in nitride read-only memories

2010

Abstract We report on the influence of different types of radiation on the nitride read-only memories (NROM®). The memory cells were irradiated by light ions (Boron), X-rays and γ-rays. Memory transistor parameters, such as threshold voltage and subthreshold drain leakage were studied as a function of the accumulated radiation dose and compared to the as-programmed (-erased) devices parameters. Their time evolution was registered in the range from few hours up to 5 months after the irradiation. The NROM® cells showed good radiation robustness up to high accumulated doses. Sufficient program margin (difference of threshold voltage in the programmed state and the read-out voltage level) remai…

Fluoride-Induced Negative Differential Resistance in Nanopores: Experimental and Theoretical Characterization

2021

We describe experimentally and theoretically the fluoride-induced negative differential resistance (NDR) phenomena observed in conical nanopores operating in aqueous electrolyte solutions. The threshold voltage switching occurs around 1 V and leads to sharp current drops in the nA range with a peak-to-valley ratio close to 10. The experimental characterization of the NDR effect with single pore and multipore samples concern different pore radii, charge concentrations, scan rates, salt concentrations, solvents, and cations. The experimental fact that the effective radius of the pore tip zone is of the same order of magnitude as the Debye length for the low salt concentrations used here is su…

A neural classifier for the optimal selection of conduction transfer functions

2008

On some issues in the computational modelling of spacer-filled channels for membrane distillation

2017

Abstract This study addresses issues which arise in the computational and experimental modelling of flow and heat/mass transfer in membrane distillation and other processes adopting spacer-filled channels (either planar or spiral wound), but have not been sufficiently clarified in the literature so far. Most of the argumentations presented are based on original computational results obtained by the authors by finite volume simulations; some literature results are also considered. The questions addressed regard the choice of scales for the reduction of data and the definition of dimensionless numbers ( Re , f , Nu , Sh ); the definition of average heat or mass transfer coefficients; the comb…

Crushing of interstellar gas clouds in supernova remnants. I. The role of thermal conduction and radiative losses

2005

We model the hydrodynamic interaction of a shock wave of an evolved supernova remnant with a small interstellar gas cloud like the ones observed in the Cygnus loop and in the Vela SNR. We investigate the interplay between radiative cooling and thermal conduction during cloud evolution and their effect on the mass and energy exchange between the cloud and the surrounding medium. Through the study of two cases characterized by different Mach numbers of the primary shock (M = 30 and 50, corresponding to a post-shock temperature $T\approx 1.7\times 10^6$ K and $\approx 4.7\times 10^6$ K, respectively), we explore two very different physical regimes: for M = 30, the radiative losses dominate the…