Selective recovery of lanthanides,uranium and thorium from Rosetta monazite mineral concentrate

An innovative procedure for the selective recovery of lanthanides using (NH₄)₂SO₄ from hydrous oxide cake produced after the alkali breakdown of monazite mineral concentrate was proposed. By applying this procedure, 94.6% of the rare earth elements (REEs) content would be dissolved. In this context, partial precipitation of light rare earth elements (LREEs) as their double sulfate took place. To separate uranium completely from thorium and the remaining REEs (5.4%) from hydrous oxide cake, an alkaline leaching procedure has been carried out by using a mixture of 1/3 (Na₂CO₃/NaHCO₃) solution. Finally, the remaining hydrous oxide cake was then dissolved in 4M HCl to separate either Th or REEs contents.     

Influence of wafer thickness and carrier recombination on the cutoff frequency of alloy-junction transistors

The influence of wafer thickness and carrier recombination on the -cutoff frequency of the “intrinsic” transistor is studied. First, M ' solution of the diffusion of minority carriers in a symmetrical junction transistor is used to find the d.c. transport factor. This is then converted to the a.c. case and finally an implicit equation is found for the cutoff frequency as a function of wafer thickness θ and surface recombination velocity S. It is shown that, for S < 3000 cm/sec, the influence of surface recombination is negligible.

At very narrow basewidths the current density is very high at the emitter edge and this decreases the diffusion length. More important seems to be the fact that the carriers' path (from slanted edge of emitter to slanted edge of collector) is longer than the geometrical basewidth. A reduction in wafer thickness decreases this effect and thus increases the cutoff frequency, in spite of increasing the current density at the emitter edge. The most important equations have been represented graphically for the particular case of the STC TK20 transistor.     

Privatization of Sanitation and Desalination Projects in Palestine

Abstract

The present problems that are related to water and sanitation in Palestine are many and varied, and the disparity between water supply and demand is growing with time due to the rapid population growth and aridity. Desalination has the potential to supply unlimited quantities of high-quality freshwater to Palestinian Communities. On the other hand, the situation of the sewerage system in the cities is extremely critical, and there are no sewerage systems in the rural areas. There is an urgent need for substantial improvements and extensions to the sewerage systems and treatment plants. The available funds for the Palestinian Water Authority (PWA) and other municipalities to implement wastewater and desalination projects are limited. As a result, it is important to fully explore the use of public-private partnerships that utilize sector resources to finance such projects. The objective of this study is to understand incentives for privatization of water supply and sanitation services, with more emphasis on the households' Affordability and Willingness-to-Pay (AWTP) for improved water and sanitation services. The results show that people in Palestine bear the burden of high water supply and sanitation costs. Privatization of the water and sanitation sector will guarantee sustainable development of these sectors under limited financial resources and dependency on external funds.     

Composition dependence of optical constants of Ge1 − xSe2Pbx thin films

Optical constants of vacuum-evaporated thin films in the Ge_1 − xSe₂Pb_x (x = 0, 0.2, 0.4, 0.6) system were calculated from reflectance and transmittance spectra. It is found that the films exhibit a non-direct gap, which decreases with increasing Pb content. The variation in the refractive index and the imaginary part of the dielectric constant with photon energy is reported. The relationship between the optical gap and chemical composition in chalcogenide glasses is discussed in terms of the average heat of atomization.     

Environmental impact assessment of bioplastics production from agricultural crop residues

Clean Technologies and Environmental Policy - Bioplastics are alternatives of conventional petroleum-based plastics. Bioplastics are polymers processed from renewable sources and are biodegradable....     

Implications of avoiding overlap between training and testing data sets when evaluating genomic predictions of genetic merit

The aim of this study was to evaluate and quantify the importance of avoiding overlap between training and testing subsets of data when evaluating the effectiveness of predictions of genetic merit based on genetic markers. Genomic selection holds great potential for increasing the accuracy of selection in young bulls and is likely to lead quickly to more widespread use of these young bulls with a shorter generation interval and faster genetic improvement. Practical implementations of genomic selection in dairy cattle commonly involve results of national genetic evaluations being used as the dependent variable to evaluate the predictive ability of genetic markers. Selection index theory was used to demonstrate how ignoring correlations among errors of prediction between animals in training and testing sets could result in overestimates of accuracy of genomic predictions. Correlations among errors of prediction occur when estimates of genetic merit of training animals used in prediction are taken from the same genetic evaluation as estimates for validation of animals. Selection index theory was used to show a substantial degree of error correlation when animals used for testing genomic predictions are progeny of training animals, when heritability is low, and when the number of recorded progeny for both training and testing animals is low. Even when training involves a dependent variable that is not influenced by the progeny records of testing animals (i.e., historic proofs), error correlations can still result from records of relatives of training animals contributing to both the historic proofs and the predictions of genetic merit of testing animals. A simple simulation was used to show how an error correlation could result in spurious confirmation of predictive ability that was overestimated in the training population because of ascertainment bias. Development of a method of testing genomic selection predictions that allows unbiased testing when training and testing variables are estimated breeding values from the same genetic evaluation would simplify training and testing of genomic predictions. In the meantime, a 4-step approach for separating records used for training from those used for testing after correction of fixed effects is suggested when use of progeny averages of adjusted records (e.g., daughter yield deviations) would result in inefficient use of the information available in the data.     

High performance computing of the Darmstadt stratified burner by means of large eddy simulation and a joint ATF-FGM approach

Current trend in design and operation of industrial gas turbines or internal combustion engines implies using the lean-fuel and stratified conditions aiming at the reduction of the harmful emissions and efficiency improvement. This has led to an increasing use of computational methodology, which allows detailed insight into combustion physics and processes controlling the emission formation. In the present work, the Darmstadt stratified burner is investigated by means of Large Eddy Simulation, implemented into the in-house, finite-volume-based numerical code FASTEST. The code solves the incompressible, variable-density Navier–Stokes equations coupled with the species transport equations. It is parallelized via domain decomposition technique using message passing interface (MPI). The complex chemical mechanisms are described by tabulated detailed chemistry utilizing the Flamelet Generated Manifolds (FGM) approach combined with the Artificially Thickened Flame model (ATF). The results obtained are comparatively assessed along with the complementary measurements. In-depth analysis of the flow field is conducted based on numerical simulations. Further studies have been carried out with respect to grid resolution and scalability.     

Discrete wavelet transform and support vector machine‐based parallel transmission line faults classification

This paper presents a scheme for classification of faults on double circuit parallel transmission lines using combination of discrete wavelet transform and support vector machine (SVM). Only one cycle post fault of the phase currents was employed to predict the fault type. Two features for each phase current were extracted using discrete wavelet transform. Thus, a total of 12 features were extracted for the six phase currents. The training data were collected, and SVM was employed to establish the fault classification unit. After that, the fault classification unit was tested for different fault states. The power system simulation was conducted using the MATLAB/Simulink program. The proposed technique took into account the mutual coupling between the parallel transmission lines and the randomness of the faults on transmission line considering time of occurrence, fault location, fault type, fault resistance, and loading conditions. The results show that the proposed technique can classify all the faults on the parallel transmission lines correctly. © 2015 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Economic Value of Tree Fruit Production in Jordan Valley from a Virtual Water Perspective

The continuous high demand of water resources for agricultural uses in Jordan is leading to a water crisis. A possible partial solution may be to import food which requires large amounts of water to grow instead of cultivating high water consuming crops. Crops such as banana and citrus cause a huge virtual water loss, which can be reduced by cultivating other less water-demanding crops. This paper focuses on analyzing the economic value of cultivating tree fruit from a virtual water perspective. The virtual water calculations in this study depend on the average rainfall, water quota, and the crops’ water requirements (CWR). The gross profit to the water use ratio showed that banana has the lowest value 0.085 JD/m³, while lemon has the highest value 1.65 JD/m³. The calculations show that the average embedded water in fruits varies from about 470 m³/ton for grapes to about 2,500 m³/ton for dates. Banana and citrus plantations consume about 21 and 71 million cubic meters (MCM) annually, respectively, which represent about 85% of the total water consumption in fruit tree plantation. The virtual water flow estimation embedded in fruits shows that Jordan imports about 77 MCM per year. However it exports about 29 MCM per year. The results were analyzed from an integrated water resources management (IWRM) perspective. The analysis shows that a way to recover some of the water costs involved in, e.g., banana production would be to increase the fertilizer cost by about 10%. This would double the water cost and increase the banana production cost by about 6.8%. Using this alternative could be a way to better manage the huge losses in virtual water involved in banana production in the Jordan Valley.