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UV/visible spectroscopic analysis of CO^(3+) and CO^(2+) during the dissolution of cobalt from mixed Co-Cu oxidized ores

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International journal of Minerals,Metallurgy and Materials 2011年第3期18卷 260-269页

作者： j. Ndalamo A.F. Mulaba-bafubiandi b.b. Mamba Department of Chemical Technology University of Johannesburg Department of Extraction Metallurgy University of Johannesburg

The leaching of cobalt from four-mixed Co-Cu oxidized ores containing cobalt at levels ranging from 0.5wt% to 34wt% was studied and the results has been reported. Conventional dissolution of these oxidized Co-Cu ores with diluted H2SO4 and SO2 as a reducing agent resulted in a substantial improvement in the solution based recovery of cobalt. UV/visible spectroscopic analysis of the leached solu-tions indicated that the increased cobalt content in the solution was a result of flushing the acidified cobalt leaching solution with SO2. Fur-thermore, UV/visible spectroscopy confirmed that as SO2 was flushed into the acidified leaching solution, Co3＋ bearing minerals were re-duced to the readily soluble Co2＋ bearing minerals, and this resulted in the increase of total cobalt in the collected solution. The mechanism of the reduction of Co3＋ to Co2＋ bearing minerals when SO2 is flushed during the leaching of mixed Co-Cu oxidized ores, including the stability trends of Co3＋, Co2＋, and Cu2＋ complexes, as shown by their UV/visible spectra, are also discussed.

关键词： cobalt metallurgy dissolution leaching reaction kinetics spectroscopic analysis

Influence of TiO_2 on the electrochemical performance of pasted typeβ-nickel hydroxide electrode in alkaline electrolyte

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journal of Energy Chemistry 2016年第1期25卷 41-48页

作者： b.Shruthi b.j.Madhu V.bheema Raju Department of Chemistry Dr. Ambedkar Institute of Technology Post Graduate Department of Physics Government Science College Department of Chemistry Dayananda Sagar College of Engineering

Nickel hydroxide was used as the positive electrode material in rechargeable alkaline batteries, which plays a significant role in the field of electric energy storage devices. β-nickel hydroxide（β-Ni（OH）2 ） was prepared from nickel sulphate solution using potassium hydroxide as a precipitating agent. Pure β-phase of nickel hydroxide was confirmed from XRD and FT-IR studies. The effects of TiO2 additive on the β-Ni（OH）2 electrode performance are examined. The structure and property of the TiO2 added β-Ni（OH）2 were characterized by XRD, TG-DTA and SEM analysis. A pasted–type electrode is prepared using nickel hydroxide powder as the main active material on a nickel sheet as a current collector. Cyclic voltammetry and electrochemical impedance spectroscopy studies were performed to evaluate the electrochemical performance of the β-Ni（OH）2 and TiO2 added β-Ni（OH）2 electrodes in 6 M KOH electrolyte. Anodic（Epa） and cathodic（Epc）peak potentials are found to decrease after the addition of TiO 2 into β-Ni（OH）2 electrode material. Further,addition of TiO2 is found to enhance the reversibility of the electrode reaction and also increase the separation of the oxidation current peak of the active material from the oxygen evolution current. Compared with pure β-Ni（OH）2 lectrode,TiO2 added β-Ni（OH）2 electrode is found to exhibit higher proton diffusion coefficient（D） and lower charge transfer resistance. These findings suggest that the TiO2 added β-Ni（OH）2 electrode possess improved electrochemical properties and thus can be recognized as a promising candidate for the battery electrode applications.

关键词： Nickel hydroxide Electrode material Thermogravimetric analysis Electrochemical properties Impedance spectroscopy

Heat and Mass Transfer Investigation of Hydrocarbon Droplet Evaporation under Rotatory Movement

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Chinese Physics Letters 2005年第11期22卷 2933-2935页

作者： j. Dgheim b. Zeghmati Groupe de Mécanique Acoustique et Instrumentation Centre d'Etudes Fondamentales UPRES EA 2986 Université de Perpignan 52 Avenue de Villeneuve 66860 Perpignan France

The steady-state boundary layer equations of a rotatory movement around hydrocarbon droplets saturated of pure fuel are numerically solved. The transfer equations are schemed by using an implicit finite difference method. The system of algebraic equations is solved by using the Thomas algorithm. The model is compared to the Kreith one and a good agreement is observed between both models. The dimensionless physical parameters of the evaporation phenomena of droplet in rotation are calculated and presented under the effect of the convection.

关键词： Heat and Mass Transfer Investigation of Hydrocarbon Droplet Evaporation under Rotatory Movement

PROXIMAL POINT ALGORITHM FOR MINIMIZATION OF DC FUNCTION

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journal of Computational Mathematics 2003年第4期21卷 451-462页

作者： Wen-yuSun Raimundo.j.b.Sampaio M.A.b.Candido SchoolofMathematicsandComputerScience NanjingNormalUniversityNanjing2100g7China ProgramadePos-GraduacaoemInformaticaAplicada PontificiaUniversidadeCatolicadoParana(PUCPR)CEP:80215-g01CuritibaPRBrazil ProgramadePos-GraduacaoemInformaticaAplicada PontificiaUniversidadeCatolicadoParana(PUCPR)CEP:80215-g01CuritibaPRBrazil

In this paper we present some algorithms for minimization of DC function (difference of two convex functions). They are descent methods of the proximal-type which use the convex properties of the two convex functions separately. We also consider an approximate proximal point algorithm. Some properties of the ε-subdifferential and the ε-directional derivative are discussed. The convergence properties of the algorithms are established in both exact and approximate forms. Finally, we give some applications to the concave programming and maximum eigenvalue problems.

关键词： Nonconvex optimization Nonsmooth optimization DC function Proximal point algorithm ε-subgradient.

SECOND-ORDER INTERACTION OF IRREGULAR WAVES WITH A TRUNCATED COLUMN

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Acta Mechanica Sinica 1997年第2期13卷 130-142页

作者： j.b.Huang R.EatockTaylor Department of Engineering Science University of OxfordParks RoadOxfordOX1 3PJUK

A complete semi-analytical solution is obtained for second-order diffraction of plane bichromatic waves by a fixed truncated circular *** fluid domain is divided into interior and exterior *** the exterior region,the second-order velocity potential is expressed in terms of‘locked-wave’and‘free-wave’ components,both are solved using Fourier and eigenfunction *** re- sulting‘locked wave’potential is expressed by one-dimensional Green's integrals with oscillating *** order to increase computational efficiency,the far-field part of the integrals are carried out *** in both regions are matched on the interface by the potential and its normal derivative continuity *** on the present approach,the sum-and difference-frequency potentials are efficiently evaluated and are used to generate the quadratic transfer functions which correlates the incident wave spectrum with second-order forcing spectrum on the *** sum-frequency QTFs for a TLP column are present,which are compared for some frequency pairs with those from a fully numerical *** agreement has been *** spectra for a case study TLP column,generated using the semi-analytical solution are *** given are the results for nonlinear wave field around the column.

关键词： marine hydrodynamics nonlinear wave force wave-structure interaction second-order wave diffraction

Comprehensive comparison and analysis of the tidal gravity observations obtained with superconducting gravimeters at stations in China,belgium and France

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Chinese Science bulletin 1999年第8期44卷 750-755页

作者： Ducarme b Hinderer j Royal Observatory of belgium B-1180 Brussels BelgiumSchool and Observatory of the Physics of the Earth 67084 Strasbourg France

The long-term tidal gravity observations of about 27 a obtained with superconducting gravimeters (SG) at stations in Wuhan (China), brussels (belgium) and Strasbourg (France) are analyzed comprehensively. The quality factors of these observations at various stations are obtained and the tidal parameters are determined accurately. The efficiency when using various procedures on improving accuracy of the tidal parameters is discussed. The loading corrections on tidal parameters are carried out based on the global ocean tidal models. The correlations between the observed residuals and air pressure change are studied, the atmospheric gravity admittances in both temporal and frequency domains are determined, and the possible reasons of inducing the discrepancy between the observed tidal parameters and those in the standard tidal models are studied.

关键词： tidal gravity superconducting gravimeter. comprehensive comparison accuracy analysis.

Comparative Larvicidal Property of Leaf Extract of Chromolaena odorata L (Composidae) and Chlopyrifos (Organophosphorus Compound) on Simulium Larvae

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biomedical and Environmental Sciences 2007年第4期20卷 313-316页

作者： b.M.MATUR b.j.DAVOU University of Abuja Department of Biological Sciences P.M.B117AbujaNigeria

To assess the phytochemical properties of Chromoleana odorata in the control of blackflies to help check the problem of environmental pollution from the use of chemical insecticides. Methods Dried pulverized leaves of Chromolaena odorata （100 g） were soaked in distilled water for 24 hours and the extract was filtered, marc pressed and evaporated over water bath. Stock solution of the dried mass （1 g） was concentrated by dissolving in 100 mL of water. Serial dilutions （100 mg/mL, 10 mg/mL, 1 mg/mL, 0.1 mg/mL, 0.01 mg/L, and 0.001 mg/mL） of both the extract and Chlopyrifos （organo phosphorus） were prepared and toxicity was tested on the larvae of Simulium species. Results The chemical compound recorded 100% larval mortality at all concentrations while the plant extract recorded 100% larval mortality in three （100, 10, and 1 mg/mL） of its diluent concentration. The percentage of larval mortality by chemical compound and plant extract was statistically insignificant （t = 0.2456, P〉0.05）, but the mortality rate was significant within 30 rain interval of exposure time （t= 3.756, P〈0.05）. The LCs0 of the plant extract was determined at about 0.001 mg/mL concentration. This showed that the plant extract had an appreciable larvicidal property close to that of the chemical compound. Conclusion This result indicates the usefulness of plant materials in the control of obnoxious insect vectors of mn. It also opens additional approach to the management of environment from toxic chemicals that are non-biodegradable and cause environmental imbalance in the ecosystem.

关键词： Chromolaena odorata Chlopyrifos Larvicidal property Simulium species

Effect of periodic heat transfer on the transient thermal behavior of a convective-radiative fully wet porous moving trapezoidal fin

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Applied Mathematics and Mechanics(English Edition) 2023年第4期44卷 653-668页

作者： b.j.GIREESHA M.L.KEERTHI Department of PG Studies and Research in Mathematics Kuvempu UniversityShankaraghatta 577451India

A moving trapezoidal profiled convective-radiative porous longitudinal fin wetted in a single-phase fluid is considered in the current *** periodic variation in the fin base temperature is taken into account along with the temperature sensitive thermal conductivity and convective heat transfer *** modeled problem,which is resolved into a non-linear partial differential equation(PDE),is made dimensionless and solved by employing the finite difference method(FDM).The results are displayed through graphs and *** effects of amplitude,frequency of oscillation,wet nature,Peclet number,and other relevant quantities on the distribution of temperature through the fin length and with the dimensionless time are *** is deciphered that the periodic heat transfer gives rise to the wavy nature of the fin thermal profile against *** analysis is beneficial in the design of fin structures for applications like solar collectors,space/airborne applications,and refrigeration industries.

关键词： convection fully wet porous fin trapezoidal profile moving fin unsteady periodic thermal condition

Effect of base Material on Microstructure and Texture Evolution of a Ti–6Al–4V Electron-beam Welded joint

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Acta Metallurgica Sinica(English Letters) 2017年第5期30卷 499-504页

作者： G.Q.Wang Z.b.Zhao b.b.Yu j.R.Liu Q.j.Wang j.H.Zhang R.Yang j.W.Li School of Materials Science and Engineering University of Science and Technology of China Institute of Metal Research Chinese Academy of Sciences Science and Technology on Power beam Processes Laboratory Beijing Aeronautical Manufacturing Technology Research Institute

The effect of base material（bM） on microstructure and crystallographic orientation evolution of a Ti–6Al–4V electron-beam welded joint was investigated. Meanwhile, the crystallographic orientation of prior b grains was studied by advanced electron backscattered diffraction data processing. The inhomogeneity of microstructure within welded joint was formed due to the different microstructures of bM. by comparing microstructure details of the welded joint, including microstructure morphology and crystallographic orientation with those of the base material, it can be found that both the microstructure morphology and crystallographic orientation of the EbW joint would be controlled by bM.

关键词： Electron-beam welding Titanium alloys Prior b orientation Microstructure Texture