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Journal of Agricultural Chemistry and Environment 2018年第4期7卷 188-202页

作者： U. A. Birnin-Yauri m. k. musa S. m. Alhaji Department of Pure and Applied Chemistry Usmanu Danfodiyo University Sokoto Nigeria Department of Chemistry Sokoto State University Sokoto Nigeria

The study was conducted to determine the concentrations of heavy metals (Cu, Zn, Co, mn, Fe, Cr, Cd and Pb) in the liver, kidney and flesh of Cattle, Sheep and Goats from Anka and Bukkuyum Local Government areas of Zamfara State Nigeria. The levels of heavy metals in the liver, kidney and flesh of beef, mutton and caprine ranged from 56 to 549 μg·g-1 for Zn;109 to 576 μg·g-1 for Fe;0.0 to 4.0 μg·g-1 for Pb;2.52 to 13.25 μg·g-1 for mn;0.00 to 19.64 μg·g-1 for Cr;0.00 to 0.25 μg·g-1 for Cd;0.00 to 2.71 μg·g-1 for Co and 3.59 to 538 μg·g-1 for Cu. The concentration of Cr, Pb and mn in the kidneys and livers of the samples were observed to be higher than the maximum allowable level. Similarly, the exception of Cr in the liver of sheep and goat from Anka and liver of sheep from Bukkuyum, Pb in some liver and kidney samples and mn in some liver, kidney samples and flesh of cattle from Anka were found to be polluted and hence unsafe for consumption.

关键词： Heavy metals Caprine mutton Beef Environment Cattle Sheep Goats

Newtonian heating effects in three-dimensional flow of viscoelastic fluid

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Chinese Physics B 2014年第5期23卷 373-379页

作者： A.Qayyum T.Hayat m.S.Alhuthali H.m.malaikah Department of mathematics Quaid-i-Azam University 45320Islamabad 44000Pakistan Department of mathematics Faculty of ScienceKing Abdulaziz University

A mathematical model is constructed to investigate the three-dimensional flow of a non-Newtonian fluid. An in-compressible viscoelastic fluid is used in mathematical formulation. The conjugate convective process （in which heat the transfer rate from the bounding surface with a finite capacity is proportional to the local surface temperature） in three-dimensional flow of a differential type of non-Newtonian fluid is analyzed for the first time. Series solutions for the nonlinear differential system are computed. Plots are presented for the description of emerging parameters entering into the problem. It is observed that the conjugate heating phenomenon causes an appreciable increase in the temperature at the stretching wall.

关键词： viscoelastic fluid three-dimensional flow Newtonian heating

Thick and Dense Anodic Oxide Layers Formed on Aluminum in Sulphuric Acid Bath

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Journal of materials Science & Technology 2010年第2期26卷 113-118页

作者： W. Bensalah m. Feki m. Wery H.F. Ayedi URCIm Department of Materials EngineeringNational School of Engineering IUT Orsay-Paris XI University Plateau du Moulon URCIm Department of Materials Engineering National School of Engineering

Thick and dense oxide layers were obtained on aluminium in sulphuric acid electrolyte. For this purpose, the methodology of experimental design was used. A three-variables Doehlert design （bath temperature, anodic current density, sulphuric acid concentration）, was achieved. In order to maximize the growth rate and the density of the anodic oxide layer, optimum path study was conducted. Under the determined optimal anodizing conditions （5.7℃, 3 ***-2,Csul=140 g.L-1）, the estimated response values were 0.86 μmin-1 and 3.12 ***-2 for growth rate and density, respectively. The morphology of optimum layer was examined by scanning electron microscopy （SEm）. The compactness of the optimum anodic layer can be correlated with its morphology revealed by SEm observations.

关键词： Sulphuric anodization Experimental design Growth rate Density

Surface Waviness in Grinding of Thin mould Insert Using Chilled Air as Coolant

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厦门大学学报（自然科学版） 2002年第S1期41卷 105-106页

作者： Yeo S H k Ramesh School of mPE Nanyang Technological UniversityGintic Institute of Manufacturing Technology Singapore Singapore

On going trend of miniaturization in electronic rel at ed parts, which is an average of two times in every 5～7 years introduce grindin g challenges. In grinding process, the surface waviness control of thin parts is an ardent task due to its warpage, induced by the high specific grinding energy (2～10 J/mm 3). Therefore, coolant is often used to avoid thermal damage, obtai n better surface integrity and to prolong wheel life. However coolant, the incomp ressibility media introduce high forces at the grinding zone creating dimensiona l as well as shape instability. In view of these situations chilled air was ap plied in place of conventional coolant. The chilled air is produced using a two -stage vapor compression refrigeration cycle with characteristics of: temperatu re -35 ℃, pressure 0.2～0.3 mPa and flow rate 0.4 m 3/min. Also traces of eco - oil mist that encompass the chilled air are supplied to the grinding zone. B oth chilled air and eco-oil mist are applied through two independent paths of a specially designed twin compartment nozzle for maximizing the penetration. This paper investigates the grinding characteristics of mold insert which is closer to m2 tool steel (component widely used in connector industries) when using chil led air as coolant media. Grinding experiments were conducted using a vitrified bond CBN wheel (B91N100V) and a surface grinder. Initial study was focussed on establishing the most suita ble clamping method for the thin mold insert. FEm analysis and grinding experime nt studies were performed to quantitatively analyze the clamping induced deflect ion. Waviness value (W t) of (24～62) μm was achieved for resin clampi n g whereas (4～8) μm, (4～6) μm were achieved for magnetic and wax clamping res pe ctively. Wax clamping is predominantly used in all the grinding experiments that characterize the grinding process, which use chilled air as the coolant media. Between 0.15 to 0.9 mm 3/mm.s of specific material removal rate, ground sur face tempe

关键词： In Surface Waviness in Grinding of Thin mould Insert Using Chilled Air as Coolant

Solution of nonlinear cubic-quintic Duffing oscillators using He’s Energy Balance method

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2009年第9期10卷 1263-1268页

作者： D.D.GANJI m.GORJI S.SOLEImANI m.ESmAEILPOUR Department of mechanical Engineering University of Mazandaran

In this study, He＇s Energy Balance method （EBm） was applied to solve strong nonlinear Duffing oscillators with cubic-quintic nonlinear restoring force. The complete EBm solution procedure of the cubic-quintic Duffing oscillator equation is presented. For illustration of effectiveness and convenience of the EBm, different cases of cubic-quintic Duffing oscillator with different parameters of α,β and y were compared with the exact solution. We found that the solutions were valid for small as well as large amplitudes of oscillation. The results show that the EBm is very convenient and precise, so it can be widely appli- cable in engineering and other sciences.

关键词： Energy Balance method (EBm) Cubic-quintic Duffing equation Oscillator

Effects of self-fields on electron trajectory and gain in two-stream electromagnetically pumped free-electron laser with ion channel guiding

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Chinese Physics B 2011年第7期20卷 158-164页

作者： S.Saviz Farzin m.Aghamir H.mehdian m.Ghorannevis Plasma Physics Research Center Science and Research BranchIslamic Azad UniversityTehranP.O.Box.14665-678Iran Department of Physics University of TehranN.Kargar AveTehran 14399Iran Department of Physics and Institute for Plasma Research Tarbiat Moallem University49Dr.Mofatteh avenueTehran 15614Iran

A theory for the two-stream free-electron laser with an electromagnetic wiggler （EmW） and an ion channel guiding is developed. In the analysis, the effects of self-fields have been taken into account. The electron trajectories and the small signal gain are derived. The stability of the trajectories, the characteristics of the linear gain and the normalized maximum gain are studied numerically. The dependence of the normalized frequency ω corresponding to the maximum gain on the ion-channel frequency is presented. The results show that there are seven groups of orbits in the presence of the self-fields, which are similar to those reported in the absence of the self-fields. It is also shown that the normalized gains of 2 groups decrease while the rest increase with the increasing normalized ion-channel frequency. Furthermore, it is found that the two-stream instability and the self-field lead to a decrease in the maximum gain except for group 4.

关键词： free electron laser two-stream

Bound States of (1+1)-dimensional Dirac Equation with kink-like Vector Potential and Delta Interaction

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Acta mathematicae Applicatae Sinica 2015年第4期31卷 1131-1140页

作者： m.ESHGHI H.mEHRABAN Sameer m.IkHDAIR Yang Researchers and Elite Club Central Tehran BranchIslamic Azad University Faculty of Physics Semnan University Department of Electrical Engineering Near East University Department of Physics Faculty of ScienceAn-Najah National University

The relativistic problem of spin-1/2 fermions subject to vector hyperbolic （kink-like） potential （- tanh kx） is investigated by using the parametric Nikiforov-Uvarov method. The energy eigenvalue equation and the ... 详细信息

关键词： (1+1)-dimensional Dirac equation kink-like potential Rosen-morse potential NU method

New turbulence modeling for air/water stratified flow

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Journal of Ocean Engineering and Science 2020年第1期5卷 55-67页

作者： m.Ghafari m.B.Ghofrani Department of Energy Engineering Sharif University of TechnologyAzadi Ave.TehranIran

The prediction of interfacial turbulence characteristics is one of the still challenging of two-phase stratified *** evaluation of some important parameters such as interfacial heat transfer coefficient based on turbulence kinetic energy and turbulence dissipation rate in some models,intensifies the importance of turbulence flow correct *** gradient of velocity and turbulence kinetic energy at the interface of two-phase stratified flow leads to a major overestimation or underestimation of flow characteristics without any special *** of a source function of turbulence eddy frequency at the interface is one of the common solution employed in past *** this solution remedies some shortcomings of traditional methods in smooth stratified flow,its application in wavy stratified flow needs the other *** examination of turbulence characteristics near the free surface reveals that,in addition to turbulence eddy frequency,the other source function of turbulence kinetic energy should be considered near the free ***,a new source function of turbulence kinetic energy is proposed at the interface based on flow *** new method has been employed for Fabre et al.(1987)experiment designed for air/water stratified *** results of simulation have a good agreement with experimental data and turbulence characteristic can be captured near the free surface.

关键词： Stratified flow Turbulence model Turbulence kinetic energy Source function

Ultrafast synthesis and sintering of materials in a single running experiment approach by using electric fields

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Journal of Advanced Ceramics 2019年第2期8卷 265-277页

作者： Lílian m.JESUS Ronaldo S.SILVA Jean-Claude m’PEkO Sao Carlos Institute of Physics University of Sao Paulo(USP)P.O.Box:369CEP:13560-970 Sao CarlosSPBrazil Group of Advanced Ceramic materials Department of PhysicsFederal University of Sergipe(UFS)CEP:49100-000 Sao CristovaoSEBrazil Department of Physics Federal University of Sao Carlos(UFSCar)13560-905 Sao CarlosSPBrazil

Processing of materials in the form of ceramics normally involves several steps including calcination at a relatively low temperature for synthesis of the end-product powder and sintering at a high temperature for *** work we have been developing introduces a novel approach enabling synthesis plus sintering of materials in a single running experiment by using electric fields,ending with dense ceramics that display grains noticeably finer than in conventional *** new paradigm is fully illustrated with experiments conducted on amorphous CaCu3Ti4O12 precursor powder,shown to experience,on heating,crystallization through intermediate phases,followed by chemical reaction leading to synthesis of the end-product powder,plus densification depending on field *** processing time and furnace temperature are considerably reduced,demonstrating that enhanced synthesis and sintering rates applied under field *** results found in Bi2/3Cu3Ti4O12are also *** different factors that may contribute to this unique scenario,including Joule heating,defect generation,and reduction of free energy for nuclei formation promoted by the applied field,are briefly ***,the findings we bring here are exclusive as they show an exploitable way that allows rapid processing of materials with good control over particle and grain coarsening.

关键词： field-assisted processing synthesis sintering microstructure dielectric response

The Influence of the Imperfectness of Contact Conditions on the Critical Velocity of the moving Load Acting in the Interior of the Cylinder Surrounded with Elastic medium

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Computers, materials & Continua 2018年第2期54卷 103-136页

作者： m.Ozisik m.A.mehdiyev S.D.Akbarov Department of mathematical Engineering Yildiz Technical UniversityDavutpasa Campus34220Esenler-Istanbul-Turkey Institute of mathematics and mechanics of the National Academy of Sciences of Azerbaijan 37041BakuAzerbaijan Department of mechanical Engineering Yildiz Technical UniversityYildiz Campus34349BesiktasIstanbulTurkey

The dynamics of the moving-with-constant-velocity internal pressure acting on the inner surface of the hollow circular cylinder surrounded by an infinite elastic medium is studied within the scope of the piecewise homogeneous body model by employing the exact field equations of the linear theory of *** is assumed that the internal pressure is point-located with respect to the cylinder axis and is axisymmetric in the circumferential ***,it is assumed that shear-spring type imperfect contact conditions on the interface between the cylinder and surrounding elastic medium are *** focus is on the influence of the mentioned imperfectness on the critical velocity of the moving load and this is the main contribution and difference of the present paper the related other *** other difference of the present work from the related other ones is the study of the response of the interface stresses to the load moving velocity,distribution of these stresses with respect to the axial coordinates and to the *** the same time,the present work contains detail analyses of the influence of problem parameters such as the ratio of modulus of elasticity,the ratio of the cylinder thickness to the cylinder radius,and the shear-spring type parameter which characterizes the degree of the contact imperfection on the values of the critical velocity and stress *** numerical results are presented and *** particular,it is established that the values of the critical velocity of the moving pressure decrease with the external radius of the cylinder under constant thickness of that.

关键词： moving internal pressure critical velocity circular hollow cylinder surrounded by elastic medium shear-spring type imperfection interface stresses