Search results for "CONDUCTIVITY"

A simple analysis of the HA centre destruction temperatures for doped alkali halides

1998

Abstract A simple relation for the destruction temperatures Td of the HA centres (H centres trapped by an impurity cation) as a function of the difference in the radii for a host cation and impurity in alkali halide crystals is presented and theoretically justified. This relation allows to predict Td for H centres trapped by other monovalent cation impurities.

Run duration effects on the hydrodynamic properties of a loam soil estimated by steady-state infiltration methods

2020

Steady-state methods for the analysis of single-ring infiltration data are commonly applied. However, the duration of an infiltrometer experiment is often established quite subjectively based on the assumption that in general infiltration stabilizes rather quickly in the field. For a loam soil, the effect of the duration of a beerkan run on sorptivity, S, and saturated hydraulic conductivity, Ks, was tested by using the BEST (Beerkan Estimation of Soil Transfer parameters)-steady method and SSBI (Steady version of the Simplified method based on a Beerkan Infiltration run) method for data analysis. The standard experiment, based on a total of 15 water volumes each establishing an initial pon…

Comparing two methods of analysis of single-ring infiltrometer data for a sandy – loam soil

2009

The single-ring pressure i n filtrometer (PI) with the steady-state Two-Ponding-Depth (TPD) applic ation method were developed to simulta neously determine the saturated soil hydraulic conductivity, K , and the α ⁎ -parameter in the fi eld. Methods of analysis of transient PI data are also available but they have received little testing so far. The transient WU method and the TPD method were compared for a sandy-loam soil. A linearization technique o f the in filtration curve yielded more reliable K fs fs and α ⁎ results (i.e., falling within expected ranges) than a non-linear optimization technique. The WU method gave both positive and reasonable K and α ⁎ values for all infi ltration tests. U…

Improvement of BEST (Beerkan Estimation of Soil Transfer parameters) method for soil hydraulic characterization

Interpreting and modeling soil hydrological processes require the determination of the soil hydraulic characteristic curves, i.e. the relationships between volumetric soil water content, pressure head, and hydraulic conductivity. Using traditional methods to determine these properties is expensive and time consuming. Haverkamp et al. (1996) pioneered a specific method for soil hydraulic characterization known as the “Beerkan method”. An improved version of this methodology, called the Beerkan Estimation of Soil Transfer parameters (BEST) procedure, was developed by Lassabatère et al. (2006) to simplify soil hydraulic characterization. BEST considers certain analytic formulae for hydraulic c…

Growth and characterisation of MnTe crystals

2001

We report on the low temperature growth of MnTe crystals by means of travelling solution methods. Two different processes are considered; a classical THM process using a low temperature presynthesised MnTe ingot, and a modified THM process, in which an increasing length of solvent zone collects the tellurium that was added to the stoichiometric charge to decrease the reaction temperature. Ingots from the two methods are analysed by means of scanning electron microscopy, X-ray diffractometry, resistivity, susceptibility and optical absorption measurements.

On Infiltration and Infiltration Characteristic Times

2022

In his seminal paper on the solution of the infiltration equation, Philip (1969), https://doi.org/10.1016/b978-1-4831-9936-8.50010-6 proposed a gravity time, tgrav, to estimate practical convergence time and the time domain validity of his infinite time series expansion, TSE, for describing the transient state. The parameter tgrav refers to a point in time where infiltration is dominated equally by capillarity and gravity as derived from the first two (dominant) terms of the TSE. Evidence suggests that applicability of the truncated two-term equation of Philip has a time limit requiring higher-order TSE terms to better describe the infiltration process for times exceeding that limit. Since …

Simplified estimation of field saturated soil hydraulic conductivity from ponded infiltration data

2013

Simple and reasonably rapid experiments are desirable to conduct a spatially distributed determination of field-saturated soil hydraulic conductivity, Kfs, that is a highly variable soil property. Bagarello et al. (2012) recently developed a simplified approach to estimate Kfs that is based on a ponded field infiltration experiment. A cylinder is inserted to a short depth into the soil, so to produce a minimal disturbance of the porous medium, and the infiltration time of a few small volumes of water repeatedly applied at the surface of the confined soil is measured. Calculating Kfs needs to determine the slope of the linearized cumulative infiltration vs. time relationship, the ring radius…

Josephson-junction-based axion detection through resonant activation

2022

We discuss the resonant activation phenomenon on a Josephson junction due to the coupling of the Josephson system with axions. We show how such an effect can be exploited for axion detection. A nonmonotonic behavior, with a minimum, of the mean switching time from the superconducting to the resistive state versus the ratio of the axion energy and the Josephson plasma energy is found. We demonstrate how variations in switching times make it possible to detect the presence of the axion field. An experimental protocol for observing axions through their coupling with a Josephson system is proposed.

Generation of travelling sine-Gordon breathers in noisy long Josephson junctions

2022

The generation of travelling sine-Gordon breathers is achieved through the nonlinear supratransmission effect in a magnetically driven long Josephson junction, in the presence of losses, a current bias, and a thermal noise source. We demonstrate how to exclusively induce breather modes by means of controlled magnetic pulses. A nonmonotonic behavior of the breather-only generation probability is observed as a function of the noise intensity. An experimental protocol providing evidence of the Josephson breather's existence is proposed.

Retrofitting existing buildings by means of innovative envelope components: low-impacting new assemblies

2020

Current policies addressing the energy efficiency of buildings aimed at the control of their overall primary energy demand, require not only that the edifice envelope has to be properly designed to optimize its thermal performances, but also that the eco-friendly properties of the involved building materials have to be properly taken into account, in order of assessing all the associated environmental costs. In fact, the design of envelope structures that are able to realize proper levels of thermal insulation and, in the same time, to employ materials characterized by low environmental impacts, are believed as the most effective strategies to be adopted in the aim of addressing the above-m…