Hydrodynamic Investigation on Deep Desulfurization of Liquid Fuel at the Microscale

Microscale processes offer a substantial advantage to the process industry as separation is conducted rapidly and efficiently. However, the effectiveness of the separation depends on the stability of the flow regime. Experimental and numerical analysis was carried out to characterize the flow patterns of polyethylene glycol 200 (PEG200) and diesel fuel at several flow ratios in order to achieve optimal conditions for a stable pattern. Computational fluid dynamics (CFD) was employed using the volume-of-fluid (VOF) model and the results were validated with the experimental data. Both experimental and numerical outcomes revealed two-phase flow patterns. These findings enable the application of the simulated module for further liquid-liquid mass transfer studies where sulfuric compounds exist as solutes in the fuel.     

Generalized magneto-thermoviscoelastic plane waves under the effect of rotation without energy dissipation

A new model of the equations of generalized thermoviscoelasticity for a thermally, isotropic and electrically conducting half-space solid whose surface is subjected to a thermal shock is given. The formulation is applied to the generalized thermoelasticity based on the Green and Naghdi (GN) theory under the effect of rotation, where there is an initial magnetic field parallel to the plane boundary of the half-space. The medium is deformed because of thermal shock and due to the application of the magnetic field, it results in induced magnetic and electric fields in the medium. The normal mode analysis is used to obtain the expressions for the variables considered. The distributions of temperature, displacement, stress, induced magnetic and electric fields are represented graphically. Comparisons are made with the results predicted by the types II and III in the presence and absence of rotation.     

Some physical properties of alkali borate tungstate glasses containing iron

A series of borotungstate glasses was prepared. The glass formation was confirmed by using X-ray diffraction measurements on the powder samples then measured using Mo¨ssbauer, differential thermal analysis (DTA), infra-red (IR) and d.c. conductivity. The iron in the alkali borate tungstate glass was found in the ferric state only. The introduction of tungsten to replace 25 mol % sodium tetraborate in the glass samples caused a little shift in the IR bands toward the lower frequency. The iron ions may act as a glass modifier whereas the tungsten ions may act as network former. The electrical conduction increased in the presence of tungsten due to the hopping mechanism between the two sites of tungsten (W⁵⁺, W⁶⁺).     

Thermal fatigue analysis of small-satellite structure

The small-satellite thermal subsystem main function is to control temperature ranges on equipments, and payload for the orbit specified. Structure subsystem has to ensure the satellite structure integrity. Structure integrity should meet two constraints; first constraint is accepted fatigue damage due to cyclic temperature, and second one is tolerable mounting accuracy at payload and Attitude Determination and Control Subsystem (ADCS) equipments’ seats. First, thermal analysis is executed by applying finite-difference method (IDEAS) and temperature profile for satellite components case is evaluated. Then, thermal fatigue analysis is performed applying finite-element analysis (ANSYS) to calculate the resultant damage due to on-orbit cyclic stresses, and structure deformations at the payload and ADCS equipments seats.     

Analysis of phenols and nitrophenols in rainwater collected simultaneously on an urban and rural site in east of France

The behaviour of phenols and nitrophenols in the atmosphere is of concern for environmental research as these are known to be toxic to humans and wildlife. To increase the knowledge about these compounds, the concentrations of 20 phenols and nitrophenols in rainwater were studied in an urban (Strasbourg) and a rural (Erstein) site in Eastern France.The wet rain samples were collected on a weekly basis between January 2002 and July 2003, and analyzed for phenols and nitrophenols using SPME and gas chromatography coupled to mass spectrometry. The compounds were derivatized with MDBSTFA directly in the injection port of the gas chromatograph.Total concentrations ranged from 0 to 1383 µg L^− 1 in Strasbourg and from 0 to 1215 µg L^− 1 in Erstein. These concentrations are in the same range than those measured in other studies, but considerably higher than the concentrations measured for pesticides (about 10 times) and polycyclic aromatic hydrocarbons (about 1000 times) on the same sites and at the same period.Phenols, except for o-cresol, were generally less concentrated than nitrophenols. o-Cresol was one of the major compounds, probably due to its role as raw material in pesticide production. The concentrations of phenols and nitrophenols were found to vary with time. No seasonal trend was observed, but significant correlations with rainfall amount were identified.     

Modeling of fluid flow and heat transfer in the plasma region of the dc electric arc furnace

A mathematical model describing the transport processes in the plasma arc in dc electric arc furnaces has been developed. The equations of conservation of mass, momentum, and energy are solved numerically in conjunction with Maxwell's equations of the electromagnetic field to calculate the velocity and temperature distributions in the plasma region. The heat transfer from the arc to a rigid anode surface is calculated. The model is applied to obtain quantitative results on the relative importance of the various modes of heat transfer from the electric arc to the anode surface. Computational results were obtained for varying arc current magnitudes and anode-cathode distances. The model predicts higher arc jet velocity and a broader arc core at higher arc current. The shorter arc length is more efficient for transferring heat to the anode.     

Efficient bi-objective ant colony approach to minimize total tardiness and system unavailability for a parallel machine scheduling problem

In recent years, decision makers give more importance to the maintenance function, viewing its substantial contribution to business productivity. However, most literature on scheduling studies does not take into account maintenance planning when implementing production schedules. The achievement of production plan without taking into account maintenance activities increases the probability of machine breakdowns, and inversely, considering maintenance actions in production planning elongates the achievement dates of orders and affects deadlines. In this paper, we propose a bi-objective model to deal with production scheduling and maintenance planning problems simultaneously. The performance criteria considered for production and maintenance are, respectively, the total tardiness and the unavailability of the production system. The start times of preventive maintenance actions and their number are not fixed in advance but considered, with the execution dates of production tasks, as decisions variables of the problem. The solution of the integrated model is based on multi-objective ant colony optimization approach. The proposed algorithm (Pareto ant colony optimization) is compared, on the basis of several metrics, with well-known multi-objective genetic algorithms, namely NSGA-II and SPEA 2, and a hybrid particle swarm optimization algorithm. Interesting results are obtained via empirical study.     

Investigation on microwave absorption characteristics of ternary MWCNTs/CoFe2O4/FeCo nanocomposite coated with conductive PEDOT-Polyaniline Co-polymers

In this study, ternary MWCNTs/CoFe₂O₄/FeCo nanocomposite coated with conductive PEDOT-polyaniline (PA@MW/F/C) co-polymers were synthesized by microwave-assisted sol-gel followed in-situ polymerization methods. The phases, crystal structures, morphologies, magnetic and electromagnetic features of the as-prepared samples were identified via XRD, SEM, XPS, VSM, and VNA respectively. Absorption characteristics were investigated in the frequency (12–18 GHz) Ku band. XRD, VSM and SEM analysis confirmed the partial reduction process of CoFe₂O₄ and successfully decorated magneto-dielectric particles with co-polymers. By measuring electromagnetic features of the samples, it was found that coating magneto-dielectric particles with conductive co-polymers improved the permittivity and dielectric constant, accordingly affecting the impedance matching characteristic and attenuation constant performance. Moreover, exchange coupling behavior was found significant impacts on the microwave absorption properties. PA@MW/F/C coated nanocomposite revealed the maximum reflection loss of ?90 dB at 13.8 GHz with 4 GHz effective bandwidth and 1.5 mm thickness. Due to the enhanced interfacial polarization, impedance matching and exchange coupling effects of the as-prepared nanocomposite, it owns excellent microwave absorption properties, which can be applied as an absorber with distinguishing features (strong absorption, thin thickness, and broadest effective bandwidth).     

Planktonic foraminiferal and paleoenvironments of the Upper Campanian-Maastrichtian succession in Wadi Qena,Egypt

Quantitative analysis of the Upper Campanian-Maastrichtian foraminiferal assemblages in Hawashiya and Umm Omeiyied exposed sections at Wadi Qena, Eastern Deseret, Egypt is reconstructed to study the paleoenvironments and relative sea level changes. This study recognizes eight planktonic biozones from CF8 to CF2. The preservation of the studied samples ranging from moderate to good and is dominated by small-sized of Heterohelix spp. and Globigerinelloides spp. reflecting nutrient-rich/eutrophic marine environments. Eleven benthonic foraminiferal biofacies are recorded and reflected inner to outer neritic environments. Three sea level drops are noted at the Upper Campanian/Early Maastrichtian; Early/Middle Maastrichtian and Maastrichtian/Paleocene boundaries. These sea level drops match well with the eustatic sea level drops which are tectonically effect especially at the Cretaceous/Paleogene (K/Pg) boundary due to the absence of CF1 to P4a subzones.     

Investigation and Analysis of Data Rate for Free Space Optical Communications System Under Dust Conditions

Wireless Personal Communications - In this study, the performance of free-space optics (FSO) communication link under dust conditions was analysed. The data were modulated by the non-return-to-zero...