We investigate the degree to which the nearly symmetric form of X-ray emission lines seen in Chandra spectra of early-type supergiant stars could be explained by a possibly porous nature of their spatially structured stellar winds. Such porosity could effectively reduce the bound-free absorption of X-rays emitted by embedded wind shocks, and thus allow a more similar transmission of redvs. blue...

This study focuses on the effects of elevated building substructure porosity on the accumulation of drifting snow. We conducted wind tunnel experiments of the snowdrift accumulation and numerical simulations to determine the flow field around a prototypical elevated building (based on the Martin A. Pomerantz Observatory or MAPO) with varying substructure porosity. We found that the total drift ...

in this work, experimental studies of internal friction coefficient and porosity of four high productive rice varieties in iran (nemat, neda, pajouhesh and pardis) have been presented. moisture content varied in four different ranges between 8 and 20%. the obtained results indicated that the internal friction coefficient decreased with increasing the moisture content from 8 to 11%, then decreas...

2014 Temperature dependence of electrical conductivity has been studied for hot pressed AlN ceramic having different volume percentage of porosity (0.2 to 15 %) in the temperature range (500 K to 950 K). It has been observed that electrical conductivity decreases by two orders of magnitude as the volume percentage of porosity increases from 0.2 to 15 %. The effect of moisture on electrical cond...

We studied the mechanism of volatile-induced surface porosity formation during the resin transfer molding (RTM) of aerospace composites using a blended benzoxazine/epoxy resin, and identified reduction strategies based on material and processing parameters. The influence of viscosity and pressure on resin volatilization were determined. Then, in situ data was collected during molding using a la...

We model the formation of lunar complex craters and investigate the effect of preimpact porosity on their gravity signatures. We find that while preimpact target porosities less than ~7% produce negative residual Bouguer anomalies (BAs), porosities greater than ~7% produce positive anomalies whose magnitude is greater for impacted surfaces with higher initial porosity. Negative anomalies result...

Dealing with several structures of different complexities, we adopt various strategies to extract information. The general idea is to find appropriate tools to analyze the variation of the corresponding autocorrelation functions. First, for homogeneous media under different conditions, we recover, in a statistical way, a relationship between porosity and the autocorrelation function. Then, for ...

In this paper nuclear techniques were used to describe the structural characteristics of ceramic samples. These samples were produced mainly with silica to simulate sandstones. Three sets of samples with different characteristics were analyzed using gamma ray transmission to obtain point by point porosity and X-ray microtomography to obtain the porosity, for 2D sections and the scanned bulk, as...

• A new in-column methacrylate-based polymerization procedure was developed for imaging the internal morphology of bare silica HPLC columns Polymerization performed in a commercial and home-made column The obtained silica/polymeric rod can be mechanically cut allowing cross section SEM allows mapping local external porosity packed could assistance to steer optimization packing processes columns...