Angular distribution of radiation in an isotropically scattering slab

The equation of radiative transfer in an isotropically scattering slab subject to general boundary conditions is solved. The Padé approximation technique is used to calculate the reflected and transmitted angular distributions. Numerical results for angular distributions through and at the boundaries of a finite slab are calculated by the Padé approximation technique. The results for a Padé approximation of [0/1] are compared with results obtained by the Galerkin method.     

Research on experiment and calculation of foam bursting device

This research presents experimental data on mechanical foam bursting device,based on the high speed of air fluid impinging insidethe foam bursting device,foam bubbles disrupted as a consequence of pressures changed very quickly as shear force and their impact forces.Experimental data on foam-bursting capacity have been presented.Designed device can provide effective foam bursting on collapse foam.     

Energy albedo for multiregion slabs

An asymptotic solution for the equation of radiative transfer in an inhomogeneous medium was obtained on the basis of the corresponding solutions for homogeneous sub-layers in the slowing down region. Function relations between the reflection and transmission coefficients for the whole slab and those of the sublayers are given. The invariant embedding concepts are used to get the reflection and transmission coefficients for the sub-layers. We assumed different models for the slowing-down kernels. Laplace transform was used to transform the Boltzmann equation to one velocity approximation with re-scaled mean-free path and single-scattering albedo. Numerical results are given for energy albedo as a function of the mass number of the host medium.     

Solute transport in sand and chalk: a probabilistic approach

A probabilistic approach is used to simulate particle tracking for two types of porous medium. The first is sand grains with a single intergranular porosity. Particle tracking is carried out by advection and dispersion. The second is chalk granulates with intergranular and matrix porosities. Sorption can occur with advection and dispersion during particle tracking. Particle tracking is modelled as the sum of elementary steps with independent random variables in the sand medium. An exponential distribution is obtained for each elementary step and shows that the whole process is Markovian. A Gamma distribution or probability density function is then deduced. The relationships between dispersivity and the elementary step are given using the central limit theorem. Particle tracking in the chalky medium is a non‐Markovian process. The probability density function depends on a power of the distance. Experimental simulations by dye tracer tests on a column have been performed for different distances and discharges. The probabilistic approach computations are in good agreement with the experimental data. The probabilistic computation seems an interesting and complementary approach to simulate transfer phenomena in porous media with respect to the traditional numerical methods. Copyright © 2006 John Wiley & Sons, Ltd.     

Hydromagnetic-gravity wave critical levels in the solar atmosphere

It is shown that the discontinuous jump in the vertical wave energy flux of slow hydromagnetic-gravity waves, occurring at a critical level, which is accompanied by wave absorption, and the existence of a reflection point imply that slow waves are trapped in the solar atmosphere. Thus such a system behaves as a leaky wave guide.     

Radiation transfer for an inhomogeneous half-space with an internal source

The emergent flux for radiation transfer in an inhomogeneous half-space with internal source is obtained in terms of the source-function of the diffuse reflection problem. Modified Eddington method is used to calculate the diffuse problem and, hence, the emergent flux. Numerical result are given and compared with previous work.On leave of absence from the Nuclear Research Centre, Cairo, Egypt.     

Open cluster membership probability based on K-means clustering algorithm

In the field of galaxies images, the relative coordinate positions of each star with respect to all the other stars are adapted. Therefore the membership of star cluster will be adapted by two basic criterions, one for geometric membership and other for physical (photometric) membership. So in this paper, we presented a new method for the determination of open cluster membership based on K-means clustering algorithm. This algorithm allows us to efficiently discriminate the cluster membership from the field stars. To validate the method we applied it on NGC 188 and NGC 2266, membership stars in these clusters have been obtained. The color-magnitude diagram of the membership stars is significantly clearer and shows a well-defined main sequence and a red giant branch in NGC 188, which allows us to better constrain the cluster members and estimate their physical parameters. The membership probabilities have been calculated and compared to those obtained by the other methods. The results show that the K-means clustering algorithm can effectively select probable member stars in space without any assumption about the spatial distribution of stars in cluster or field. The similarity of our results is in a good agreement with results derived by previous works.     

GIS-based multi-criteria land suitability analysis for sustainable agriculture in the northeast area of Tadla plain (Morocco)

Assessment of soil suitability for sustainable intensive agriculture is an appropriate tool to select the land suitable for agricultural production with the least economic and environmental costs. This study was conducted to evaluate the agricultural soil quality in the northeast area of Tadla plain (Morocco) using geographic information system (GIS) and analytical hierarchy process (AHP). Six soil quality indicators, i.e., pH, organic carbon, cation exchange capacity, texture, salinity and slope were considered and performed in 60 subsurface soil samples. AHP method was utilized to identify the weight of each indicator from the pairwise comparison matrix. The weighted sum overlay analysis was then used to generate the soil quality map in a GIS environment, by overlaying both indicator weights and sub-indicator weights. The studied area was classified into four soil quality categories, i.e., poor, medium, good, and excellent, the percentage of each category is 1.12, 20.98, 61.07 and 16.83%, respectively. The results indicated that 1.12% of the study area has poor suitability for sustainable intensive agriculture due to their unsuitable texture and low salinity, while about 77% of cultivated soils are adapted to agricultural production. The above results could be useful for the management of agricultural activity.     

Leachability of radium-226 from industrial phosphogypsum waste using some simulated natural environmental solutions

This study investigated the leaching of radium-226 from phosphogypsum (PG) waste produced from the fertilizer industry by synthetic solutions that replicate water that may contact the waste in natural conditions. The results indicated that the activity concentration of Ra-226 in the PG was 461 ± 12 Bq kg^?1 and compared with other studies carried out worldwide. The leached percentage of Ra-226 represents the exchangeable fraction loosely bounded in the matrix of the PG waste. The leached fraction of Ra-226 was 6.5 ± 0.6 and 9.0 ± 0.5% when the waste was exposed to rainwater and saline solution, respectively. It is also found that the leaching fraction increased 10–12 ± 0.4% when the waste was exposed to the admixture of saline solution containing Sr²⁺ or Ba²⁺ cations, whereas it was lowered to 4–5 ± 0.5% in the presence of carbonate or sulfate anions. When the PG is used as an economic fertilizer, the irrigation water can leach 7.8 ± 0.6% of Ra-226 that could contribute to plant uptake, thereby to animal and/or human consumption. The primary tests of the drinking water (well and tap resources) consumed by the populations surround the PG facility showed that the activity concentration of Ra-226 was below the minimum detectable activity.     

Numerical heat and fluid flow modeling of the Hercynian Draa Sfar polymetallic (Zn–Pb–Cu) massive sulfide deposit,Central Jbilets,Morocco

Draa Sfar is a polymetallic (Zn–Pb–Cu) volcanogenic massive sulfide deposit with an actual resource of 13 Mt at 4.0% Zn and 1.3% Pb. It is part of the central Jbilets area known for its several Cu–Zn ore deposits. The ore is hosted in the upper Visean-Namurien sedimentary formation. Owing to the complexity of the geology of the ore deposits, numerical simulation approach was attempted to shed light into the temperature distribution, the circulation of the hydrothermal fluid and the genesis of massive sulfide ore bodies by evaluating the permeability, porosity, and thermal conductivity. On the basis of this simulation approach, the ore is predicted to be deposited at a temperature ranging between 230 and 290 °C. This temperature range is dependent on the pre-existing temperature of the discharge area where a metal-rich fluid precipitated the ore. The duration of the Draa Sfar ore body formation is predicted to be 15, 000 to 50, 000 years. Based on geological studies of Draa Sfar deposit together with the aforementioned results of the simulation approach, an ore genetic model for the massive sulfide ore bodies is proposed. In this model, the supply of ore-forming fluids is ensured by the combination of seawater and magmatic waters. Magma that generated rhyodacite dome acted as the heat source that remobilized the circulation of these ore-bearing fluids. The NW-SE trending faults acted as potential pathways for both the downward and upward migration of the ore-forming fluids. Due to their high permeability, the ignimbritic facies, host rocks of Draa Sfar ore bodies, have favored the circulation of the fluids. The mixing between the ore-forming fluids of magmatic origin and the descending seawaters and/or in situ pore waters led to the formation the ore bodies in 35,000 years. The position and size of the ore body, determined by the simulation approach, is consistent with the actual field geological data.