Search results for "Power law"
showing 8 items of 188 documents
Dielectric properties of water/lecithin/cyclohexane gels
1993
Dielectric relaxation measurements in the frequency range 0.1–15 GHz have been carried out on water/lecithin/cyclohexane gels using a time domain reflectometry method (TDR). Dielectric dispersions describable in terms of a power law typical of percolated systems, but with exponents significantly different from those characterizing statically or dynamically percolated systems are observed. The dielectric dispersions, attributed to water and/or lecithin head group rotational motions, indicate that these motions are characterized by a wide spectrum of relaxation times.
Testing warm Comptonization models for the origin of the soft X-ray excess in AGNs
2018
The X-ray spectra of many active galactic nuclei (AGN) show a soft X-ray excess below 1-2 keV on top of the extrapolated high- energy power law. The origin of this component is uncertain. It could be a signature of relativistically blurred, ionized reflection, or the high-energy tail of thermal Comptonization in a warm (kT $\sim$ 1 keV), optically thick ($\tau\simeq$ 10-20) corona producing the optical/UV to soft X-ray emission. The purpose of the present paper is to test the warm corona model on a statistically significant sample of unabsorbed, radio-quiet AGN with XMM-newton archival data, providing simultaneous optical/UV and X-ray coverage. The sample has 22 objects and 100 observations…
Melt extraction and accumulation from partially molten rocks
2004
Current models for melt segregation and ascent are not adequate to accurately describe transport and accumulation in combination. We propose that transport is discontinuous and in batches, and that accumulation occurs by stepwise merging of batches. A simple numerical model of jostling spheres that merge when they touch was used to represent stepwise accumulation and transport of batches by propagation of hydrofractures. Results of the numerical model indicate that such a system may quickly develop into a self-organised critical (SOC) state. In this state, the distribution of melt batch volumes can be described by a power law, with an exponent m that lies between 2/3 and 1. Once a self-orga…
Features of W production in p-p, p-Pb and Pb-Pb collisions
2017
We consider the production of inclusive W bosons in variety of high-energy hadronic collisions: p--p, p--$\overline{\rm p}$, p--Pb, and Pb--Pb. In particular, we focus on the resulting distributions of charged leptons from W decay that can be measured with relatively low backgrounds. The leading-order expressions within the collinearly factorized QCD indicate that the center-of-mass energy dependence at forward/backward rapidities should be well approximated by a simple power law. The scaling exponent is related to the small-$x$ behaviour of the quark distributions, which is largely driven by the parton evolution. An interesting consequence is the simple scaling law for the lepton charge as…
The WEBT BL Lacertae Campaign 2001 and its extension : Optical light curves and colour analysis 1994–2002
2004
BL Lacertae has been the target of four observing campaigns by the Whole Earth Blazar Telescope (WEBT) collaboration. In this paper we present UBVRI light curves obtained by theWEBT from 1994 to 2002, including the last, extended BL Lac 2001 campaign. A total of about 7500 optical observations performed by 31 telescopes from Japan to Mexico have been collected, to be added to the ∼15 600 observations of the BL Lac Campaign 2000. All these data allow one to follow the source optical emission behaviour with unprecedented detail. The analysis of the colour indices reveals that the flux variability can be interpreted in terms of two components: longer-term variations occurring on a fewday time …
Spatially Resolved Broadband Synchrotron Emission from the Nonthermal Limbs of SN1006
2018
We present ~400ks NuSTAR observations of the northeast (NE) and southwest (SW) non-thermal limbs of the Galactic SNR SN1006. We discovered three sources with X-ray emission detected at >50keV. Two of them are identified as background AGN. We extract the NuSTAR spectra from a few regions along the non-thermal limbs and jointly analyze them with the XMM-Newton spectra and the radio data. The broad-band radio/X-ray spectra can be well described with a synchrotron emission model from a single population of CR electrons with a power law energy distribution and an exponential cutoff. The power law index of the electron particle distribution function (PDF) is ~1.88-1.95 for both the NE and SW l…
A Power Law Behavior in the Incentivized Italian Photovoltaic Market
2018
The Italian photovoltaic (PV) marketis analyzed by using the data contained in the database that describes all PV Plants installed in Italy under the incentive program called “2nd Conto Energia”. It is shown that the cumulative probability distribution of the size of the installed PV plants has a broken power tail. An approach to partially quantify the effect of the economic, juridical and technical rules is introduced in order to show how the regulatory body influences the power tail of the cumulative probability curve.
Fractional viscoelastic transversally isotropic Timoshenko beam
2014
In this paper the viscoelastic behavior of pultruded beams has been examined. Pultruded beams are constituted by a polymer infilled with reinforcement in longitudinal direction, while in the orthogonal direction no fiber are present for technological reasons. As a consequence the material has two different behaviors in longitudinal and in orthogonal directions. It follows that pultruded beams are transversally isotropic, and the shear deformation may not be neglected. Based upon the previous observations and assuming for Creep and/or Relaxation test the power law, the constitutive equations are ruled by fractional operators. From constitutive laws, and assuming the Timoshenko beam theory to…