Search results for "Power law"
showing 10 items of 188 documents
Time evolution of size and polydispersity of an ensemble of nanoparticles growing in the confined space of AOT reversed micelles by computer simulati…
2005
The time dependence of size and polydispersity of an ensemble of nanoparticles growing in the confined space of water-containing AOT reversed micelles has been investigated by computer simulations. It has been found that, in a wide time range, the mean nanoparticle size can be described by power laws whose exponent is critically dependent on the efficiency of the intermicellar material exchange process while the nanoparticle polydispersity increases with time. From the analysis of all the disentangled effects arising from the variation of internal and external parameters provided by simulations, useful suggestions for a better and rationale control of the nanoparticle synthetic procedure ar…
Diffusion Measurements on Crystalline Rock Matrix
1994
AbstractA new gas flow technique is introduced such that experiments on very long samples are possible. This new technique together with increased accuracy of the measurements, allows the observation of power law tails in the break-through curves. Dispersion in these experiments can be controlled in great detail, and therefore the power law tails can be used to determine very accurately the parameters relevant in matrix diffusion. Results for rock and metal samples are shown, and they are fitted with model calculations which include both dispersion and matrix diffusion. The introduced technique, which is designed for ordinary drill cores, is suitable for scanning a large number of samples i…
Aging, rejuvenation, and memory phenomena in a lead-based relaxor ferroelectric
2002
Isothermal aging and temperature cycle experiments were done on the relaxor ferroelectric lead magnesium niobate mixed with 10% lead titanate (PMN-10PT) around and below the diffuse maximum of the dielectric loss. With increasing aging time tw the isothermal evolution of the linear susceptibility follows a power law and does not show frequency scaling. The non-linear susceptibility, however, obeys nearly perfect ωt w-scaling. After aging the sample at a single temperature we observed both rejuvenation and memory effects in temperature cycle experiments. This observation indicates symmetric behavior in the sense that it shows up irrespective of whether cooling with subsequent re-heating or h…
Carrier transport mechanism in the SnO(2):F/p-type a-Si:H heterojunction
2011
We characterize SnO(2):F/p-type a-Si:H/Mo structures by current-voltage (I-V) and capacitance-voltage (C-V) measurements at different temperatures to determine the transport mechanism in the SnO2:F/p-type a-Si:H heterojunction. The experimental I-V curves of these structures, almost symmetric around the origin, are ohmic for vertical bar V vertical bar< 0:1 V and have a super-linear behavior (power law) for vertical bar V vertical bar < 0:1 V. The structure can be modeled as two diodes back to back connected so that the main current transport mechanisms are due to the reverse current of the diodes. To explain the measured C-V curves, the capacitance of the heterostructure is modeled as the …
Linear and nonlinear fractional hereditary constitutive laws of asphalt mixtures
2016
The aim of this paper is to propose a fractional viscoelastic and viscoplastic model of asphalt mixtures using experimental data of several tests such as creep and creep recovery performed at different temperatures and at different stress levels. From a best fitting procedure it is shown that both the creep one and recovery curve follow a power law model. It is shown that the suitable model for asphalt mixtures is a dashpot and a fractional element arranged in series. The proposed model is also available outside of the linear domain but in this case the parameters of the model depend on the stress level.
Analytic solutions of the diffusion-deposition equation for fluids heavir than atmospheric air
2008
A steady-state bi-dimensional turbulent diffusion equation was studied to find the concentration distribution of a pollutant near the ground. We have considered the air pollutant emitted from an elevated point source in the lower atmosphere in adiabatic conditions. The wind velocity and diffusion coefficient are given by power laws. We have found analytical solutions using or the Lie Group Analysis or the Method of Separation of Variables. The classical diffusion equation has been modified introducing the falling term with non-zero deposition velocity. Analytical solutions are essential to test numerical models for the great difficulty in validating with experiments.
Finite-size scaling and the crossover to mean-field critical behavior in the two-dimensional Ising model with medium-ranged interactions.
1993
Critical amplitudes in finite-size scaling relations show a singular dependence on the range of the interactions, R. The respective power laws are predicted from phenomenological crossover scaling considerations. These predictions are tested by Monte Carlo simulations for medium-ranged Ising square lattices. It is speculated that some deviations between the simulation results and corresponding predictions may be due to logarithmic corrections.
Electron-phonon heat transport in arrays of Al islands with submicrometer-sized tunnel junctions.
1996
We present experimental evidence of the effect of electrode volume and its shape on thermalization of small metallic islands for single electron tunneling. We have investigated the power law and the magnitude of the thermal transport and found that it obeys the common ${T}^{5}$ law for electron-phonon coupling only for the smallest islands studied, and in other cases considered, with cooling fins attached to the islands, the coupling per unit volume is weaker and it rather follows a law $\ensuremath{\propto}{T}^{p}$, where $pl5$. We attribute this to local hot electrons adjacent to the tunnel junctions.
The effect of wind on jumping distance in ski jumping – fairness assessed
2012
The special wind compensation system recently adopted by Federation Internationale de Ski (FIS; International Ski Federation) to consider the effects of changing wind conditions has caused some controversy. Here, the effect of wind on jumping distance in ski jumping was studied by means of computer simulation and compared with the wind compensation factors used by FIS during the World Cup season 2009/2010. The results showed clearly that the effect of increasing head/tail wind on jumping distance is not linear: +17.4 m/ − 29.1 m, respectively, for a wind speed of 3 m/s. The linear formula used in the trial period of the wind compensation system was found to be appropriate only for a limited…
Plasmon mass scale in two dimensional classical nonequilibrium gauge theory
2018
We study the plasmon mass scale in weakly coupled strongly interacting nonabelian gauge theory in a two dimensional configuration that mimics the boost invariant initial color fields in a heavy ion collision. We numerically measure the plasmon mass scale using three different methods: a Hard Thermal Loop (HTL) expression involving the quasiparticle spectrum constructed from Coulomb gauge field correlators, an effective dispersion relation and the measurement of oscillations between electric and magnetic energies after introducing a spatially uniform perturbation to the electric field. We find that the hard thermal loop expression and the uniform electric field measurement are in rough agree…