Electromagnetically Modified Filtration of Liquid Aluminium With a Ceramic Foam Filter

Conventional Ceramic Foam Filter(CFF)technology has some difficulties in removing fine particulates(e.g.<20μm)from liquid aluminium.In the present work the filtration behaviour of 30,50 and 80 ppi CFF filters have been studied in the presence of magnetic fields in the range of 0.06-0.2T,produced by induction coils operated at 50 Hz.A feed recipe containing 90 wt.%of the aluminium alloy A356 doped with 10 wt.%A356 composite,containing 15 wt%SiC particles with a particle size ranging from 13 to 23μm,was used.When the results obtained for the experiments conducted under the influence of a magnetic field where compared with similar reference gravity filtration experiments profound changes were observed in the distribution of particulates within,over and below the filter.Significant improvements in the wetting behaviour of the liquid metal to the CFF surface were also observed.It is believed that a successful change in filtration mechanisms is obtained as a result of the presence of the Lorentz forces and the metal recirculation produced by the magnetic field.The magnitude of the Lorentz forces,i.e.the magnetic pressure,are in the present work discussed in relation to the filtration results,and quantified based on experimental data and validated 2D axial symmetric Finite Element Modelling(FEM).     

Electromagnetically Modified Filtration of Aluminum Melts—Part I: Electromagnetic Theory and 30 PPI Ceramic Foam Filter Experimental Results

In the present work, laboratory-scale continuous filtration tests of liquid A356 aluminum alloy have been performed. The tests were conducted using standard 30 PPI (pores per inch) ceramic foam filters combined with magnetic flux densities (~0.1 and 0.2 T), produced using two different induction coils operated at 50 Hz AC. A reference filtration test was also carried out under gravity conditions, i.e., without an applied magnetic field. The obtained results clearly prove that the magnetic field has a significant affect on the distribution of SiC particles. The influence of the electromagnetic Lorentz forces and induced bulk metal flow on the obtained filtration efficiencies and on the wetting behavior of the filter media by liquid aluminum is discussed. The magnitudes of the Lorentz forces produced by the induction coils are quantified based on analytical and COMSOL 4.2^® finite element modeling.     

Mechanically activated reactive synthesis of refractory molybdenum and tungsten silicides

In this study, processing of elemental powders mixtures was carried out by mechanical alloying (MA) and heat treatment in vacuum at 700–1000 °C for 1 h. The phase transformation of the powders was investigated by X-ray diffractometer (XRD). The results showed that mechanical alloying promoted the formation of a solid solution of elemental powders. The energy stored in the powders was increased as a result of exterior energy and the barrier energy of the formation of the compound could be exceeded easily. Intermetallics of MoSi₂, WSi₂, Mo₅Si₃, Mo₃Si and SiC/MoSi₂ composite powders were synthesized by mechanically activated reactive synthesis (MARS). The mechanically induced self-sustaining reaction was observed in MoSi₂ and MoSi₂ + 10 wt%SiC stoichiometry system. It has concluded that mechanically activated reactive synthesis is an effective method for the preparation of high melting-point refractory compounds.     

TD-LTE抢占无线全新商机带动全球发展势态

1 前言 LTE是目前大部分电信运营商首选的下一代移动通信技术,全球已有100多家运营商承诺于2010年开始部署LTE。不过,在非成对频段上部署LTE的商机却常被忽略。     

Removal and recovery of uranium from aqueous solutions by Trichoderma harzianum

Removal and recovery of uranium from dilute aqueous solutions by indigenously isolated viable and non-viable fungus (Trichoderma harzianum) and algae (RD256, RD257) was studied by performing biosorption-desorption tests. Fungal strain was found comparatively better candidate for uranium biosorption than algae. The process was highly pH dependent. At optimized experimental parameters, the maximum uranium biosorption capacity of T. harzianum was 612 mg U g(-1) whereas maximum values of uranium biosorption capacity exhibited by algal strains (RD256 and RD257) were 354 and 408 mg U g(-1) and much higher in comparison with commercially available resins (Dowex-SBR-P and IRA-400). Uranium biosorption by algae followed Langmuir model while fungus exhibited a more complex multilayer phenomenon of biosorption and followed pseudo-second-order kinetics. Mass balance studies revealed that uranium recovery was 99.9%, for T. harzianum, and 97.1 and 95.3% for RD256 and RD257, respectively, by 0.1M Hydrochloric acid which regenerated the uranium-free cell biomass facilitating the sorption-desorption cycles for better economic feasibility.     

Incorporation of Solid Solution Alloying Effects into Polycrystal Modeling of Mg Alloys

Discrepancies between the strength of slip systems determined directly from Mg single-crystal studies and those estimated from polycrystal simulations of Mg alloys are known to exist. These discrepancies have prohibited the direct use of single-crystal data within polycrystal models, ultimately leading to an increase in the number of adjustable parameters in such models and, accordingly, difficulties in extending such models to Mg alloys of industrial and technological relevance. In this work, a framework is introduced that eliminates these differences by accounting for continuum mechanical and physical metallurgical effects. With respect to the former, it is shown that a stiffer self-consistent grain–matrix interaction scheme than that commonly used better captures the behavior of textured Mg alloy AZ31. With respect to the latter, the impact of grain size and solute concentration on individual deformation modes is considered. Because of a lack of sufficient experimental data describing all possible deformation modes, only basal slip and prismatic slip are treated quantitatively. Of particular note is the strong solid solution strengthening of the basal slip mode and the moderate solute softening of the prismatic slip mode by the common alloying elements Al and Zn. An empirical model describing the Zn solute and temperature dependence of thermally activated prismatic slip is presented. The presented methodology provides a first attempt to eliminate the need for trial-and-error–based approach for determining the slip system flow stress parameters of polycrystal models. Areas where advances in the presented analysis may be attained are highlighted.     

Coupled transport of Pb2+ through tri‐n‐octylamine‐xylene‐polypropylene supported liquid membranes

Transport of Pb²⁺ was carried from acidic solution into alkaline stripping phase through tri‐n‐octylamine‐xylene‐polypropylene supported liquid membrane. The transport of Pb²⁺ through the membrane was studied by varying the concentration of Pb²⁺ and HNO₃ in feed solution, NaOH concentration in strip solution and TOA concentration in membrane phase. The flux data obtained has been used to study the stoichiometry of complex Pb(NO₃)_n+2(HNR₃)_n. The supported liquid membrane (SLM) has been found stable for 10 runs with 24 h between each run. This SLM has been used effectively to extract lead ions along with chromium, copper and zinc ions from aqueous acidic leached solution of paint and industrial effluents. © 2012 Canadian Society for Chemical Engineering     

Synthesis of Polyelectrolyte and Studies of its Conductivity Changes with Respect to Molecular Weight

Aqueous solutions of acrylamide monomer were irradiated by γ-rays using a Co-60 source to synthesize polyacrylamide of different molecular weight (M_w). Solubility tests together with ultraviolet and infrared spectroscopic studies were performed for examining the irradiated samples to ensure that the prepared products were gradually converted from monomer to polymer (polyacrylamide), depending on the radiation dose. Various physico-chemical properties like polymer conversion, gel content, viscosity, and molecular weight of the products were determined. The conversion of polymer from monomer is initiated at a dose of 0.06 kGy and completed at about 0.14 kGy. The gel point, which indicates a dose for the onset of a network polymer structure, is identified to be 0.15 kGy providing valuable information about γ-ray synthesis of polyacrylamides. Viscosity and molecular weight are found to increase with radiation dose. Since polyacrylamides exhibit polyelectrolytic behavior in aqueous solutions, studies on conductivity changes of polyelectrolytes with respect to M_w, which is the main issue of this investigation, also were performed. The equivalent conductance of polyelectrolyte solutions was found to decrease with the molecular weight of the synthesized polymer. This change of conducting property of the prepared samples is explained based on the theory of polyelectrolyte solutions.     

Sorption potential of rice husk for the removal of 2,4-dichlorophenol from aqueous solutions: kinetic and thermodynamic investigations

The sorption potential of chemically and thermally treated rice husk (RHT) for the removal of 2,4-dichlorophenol (DCP) from aqueous solutions has been investigated. Sorption of DCP by rice husk was observed over a wide pH range of 1-10. The effect of contact time between liquid and solid phases, sorbent dose, pH, concentration of sorbate and temperature on the sorption of DCP onto rice husk has been studied. The pore area and average pore diameter of RHT by BET method are calculated to be 17+/-0.6 m2g-1 and 51.3+/-1.5 nm, respectively. Maximum sorption (98+/-1.2%) was achieved for RHT from 6.1x10(-5) moldm(-3) of sorbate solution using 0.1g of rice husk for 10 min agitation time at pH 6 and 303K, which is comparable to activated carbon commercial (ACC) 96.6+/-1.2%, but significantly higher than chemically treated rice husk (RHCT) 65+/-1.6% and rice husk untreated (RHUT) 41+/-2.3%. The sorption data obtained at optimized conditions was subjected to Freundlich, Langmuir and Dubinin-Radushkevich (D-R) isotherms. Sorption intensity 1/n (0.31+/-0.01) and sorption capacity multilayer C(m) (12.0+/-1.6 mmolg(-1)) have been evaluated using Freundlich sorption isotherm, whereas the values of sorption capacity monolayer Q (0.96+/-0.03 mmolg(-1)) and binding energy, b, (4.5+/-1.0)x10(4)dm(3)mol(-1) have been estimated by Langmuir isotherm. The Langmuir constant, b, was also used to calculate the dimensionless factor, R(L), in the concentration range (0.6-6.1)x10(-4) moldm(-3), suggesting greater sorption at low concentration. D-R sorption isotherm was employed to calculate sorption capacity X(m) (2.5+/-0.07 mmolg(-1)) and sorption energy E (14.7+/-0.13 kJmol(-1)). Lagergren and Morris-Weber equations were employed to study kinetics of sorption process using 0.2g of RHT, 25 cm(3) of 0.61x10(-4)moldm(-3) sorbate concentration at pH 6, giving values of first-order rate constant, k, and rate constant of intraparticle transport, R(id), (0.48+/-0.04 min(-1) and 6.8+/-0.8 nmolg(-1)min(-1/2), respectively) at 0.61x10(-4)moldm(-3) solution concentration of DCP, 0.1g RHT, pH 6 and 2-10min of agitation time. For thermodynamic studies, sorption potential was examined over temperature range 283-323 K by employing 6.1x10(-4)moldm(-3) solution concentration of DCP, 0.1g RHT at pH 6 and 10 min of agitation time and values of DeltaH (-25+/-1 kJmol(-1)), DeltaS (-61+/-4 Jmol(-1)K(-1)) and DeltaG(303K) (-7.1+/-0.09 kJmol(-1)) were computed. The negative values of enthalpy, entropy, and free energy suggest that the sorption is exothermic, stable, and spontaneous in nature.     

Young children's productivity with word order and verb morphology.

Four studies examined English-speaking children's productivity with word order and verb morphology. Two- and 3-year-olds were taught novel transitive verbs with experimentally controlled argument structures. The younger children neither used nor comprehended word order with these verbs; older children comprehended and used word order correctly to mark agents and patients of the novel verbs. Children as young as 2 years 1 month added -ing but not -ed to verb stems; older children were productive with both inflections. These studies demonstrate that the present progressive inflection is used productively before the regular past tense marker and suggest that productivity with word order may be independent of developments in verb morphology. The findings are discussed in terms of M. Tomasello's (1992a) Verb Island hypothesis and M. Rispoli's (1991) notion of the mosaic acquisition of grammatical relations. (PsycINFO Database Record (c) 2010 APA, all rights reserved)