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Low cycle fatigue properties and cyclic deformation behavior of as-extruded AZ31 magnesium alloy

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Transactions of Nonferrous Metals Society of China 2010年第B07期20卷 533-539页

作者： S.kWON k.SONG k.S.SHiN S.i.kWUN Department of Materials Science and Engineering Korea University School of Materials Science and Engineering Seoul National University

The low cycle fatigue(LCF)properties of as-extruded AZ31 Mg alloy were investigated under total strain amplitudes in the range of 0.4%-1.2%with strain rate of 1×10- 2s -*** to the twinning effect in compression during loading and the detwinning effect during unloading,the alloy showed an asymmetric hysteresis *** cyclic stress response exhibited cyclic hardening at high total strain *** cyclic deformation behaviors were discussed using the Coffin-Manson plot,which divided the plastic strain amplitudes into the tension side and the compression *** the LCF tests that were started from either tension or compression under a total strain amplitude of 1.0%,the interaction between the twinning effect and dislocation was *** twinning effect during the LCF test and the variation of the dislocation density were investigated using optical microscopy and transmission electron microscopy,respectively.

关键词： AZ31 magnesium alloy low cycle fatigue twinning dislocation

Flower-shaped CuO Nanostructures: Synthesis,Characterization and Antimicrobial Activity

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Journal of Materials Science & Technology 2013年第10期29卷 909-914页

作者： k.Mageshwari r.Sathyamoorthy PG & research Department of Physics Kongunadu Arts and Science College

in the present work, flower-like CuO nanostructures were synthesized by reflux condensation method without using any surfactants or templates. Structural analysis by X-ray diffraction （XrD）, Fourier transform infrared spectroscopy （FTir） and raman studies revealed the formation of highly crystalline single phase CuO, exhibiting monoclinic structure. Morphological analysis by field emission scanning electron microscopy （FESEM） showed flower-shaped CuO hierarchical architecture made up of interpenetrating self-assembled nanosheets. Optical analysis by UV-Vis diffused reflectance spectra （DrS） exhibited considerable blue-shift in the optical band gap due to quantum confinement effect. Photoluminescence （PL） spectrum showed both UV as well as visible emissions. The antibacterial activity of flower-shaped CuO nanostructures were tested against gram-positive （Bacillus subtilis, Bacillus thuringiensis） and gram-negative （Salmonella paratyphi, Salmonella paratyphi-a, Salmonella paratyphi-b, Escherichia coil and Pseudomonas aeruginosa） bacteria. Also, the antifungal activity of CuO was investigated against Aspergillus niger, rhizopus oryzae, Aspergi/lus flavus, Cladosporium carrionii, Mucor, Penicilliurn notatum and Alternaria alternata. results demonstrate that the flower-shaped CuO nanostructures act as an effective antimicrobial agent against pathogenic bacteria and fungi.

关键词： CuO nanosheets Hierarchical X-ray diffraction Photoluminescence Antibacterial Antifungal

New exact solutions of the Einstein-Maxwell equations for magnetostatic fields

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Chinese Physics B 2012年第9期21卷 103-108页

作者： Nisha Goyal r.k.Gupta School of Mathematics and Computer Applications Thapar University

The symmetry reduction method based on the Frechet derivative of differential operators is applied to investigate symmetries of the Einstein-Maxwell field equations for magnetostatic fields, which is a coupled system of nonlinear partial differential equations of the second order. The technique yields invariant transformations that reduce the given system of partial differential equations to a system of nonlinear ordinary differential equations. Some of the reduced systems are further studied to obtain the exact solutions.

关键词： Einstein-Maxwell equations symmetry reduction method exact solutions

Effect of Post Heat Treatment on Corrosion resistance of Phytic Acid Conversion Coated Magnesium

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Journal of Materials Science & Technology 2013年第2期29卷 180-186页

作者： r.k. Gupta k. Mensah-Darkwa D. kumar Engineering research Center for revolutionizing Metallic Biomaterials (ErC-rMB) Department of Mechanical Engineering North Carolina A&T State University 1601 East Market Street Greensboro NC 27411 USA

An environment friendly chemical conversion coating for magnesium was obtained by using a phytic acid solution. The effect of post-coating 1heat treatment on the microstructures and corrosion properties of phytic acid conversion coated magnesium was investigated. it was observed that the microstructure and corrosion resistive properties were improved for the heat treated samples. The corrosion current density for bare magnesium, phytic acid conversion coated magnesium, and post-coating heat treated magnesium was calculated to be 2.48 ×10^-5, 1.18×10^-6, and 9.27 × 10^7 A/cm^2, respectively. The lowest corrosion current density for the heat treated sample indicated its highest corrosion resistive effect for the magnesium. The maximum corrosion protective nature of the heat treated sample was further confirmed by the largest value of impedance in electrochemical impedance spectroscopy studies.

关键词： Magnesium Phytic acid Corrosion impedance spectroscopy Scanning electron microscopy

Corrosion Protective Conversion Coatings on Magnesium Disks Using a Hydrothermal Technique

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Journal of Materials Science & Technology 2014年第1期30卷 47-53页

作者： r.k.Gupta k.Mensah-Darkwa D.kumar Department of Chemistry Pittsburg State University Engineering research Center for revolutionizing Metallic Biomaterials(ErC-rMB) Department of Mechanical EngineeringNorth Carolina A&T State University

A uniform, compact, and well adherent conversion coating of magnesium hydroxide has been formed on bioresorbable magnesium disks by means of a hydrothermal technique. Electrochemical results indicate that the coating brings about a significant reduction in magnesium corrosion in phosphate buffered saline （PBS） solution. it is also observed that corrosion resistance of the coating increases with an increase in treatment time, which in turn, increases the coating thickness. The protective behavior of magnesium hydroxide coating is attributed to its chemical inertness in PBS solution. The coatings are found to be free from pores that reduce the direct contact between corroding media and underlying magnesium.

关键词： Magnesium Polarization Electrochemical impedance spectroscopy (EiS) Scanning electron microscopy (SEM) Conversioncoating Corrosion

Mechanical and Corrosion Properties of Magnesiume-Hydroxyapatite (MgeHA) Composite Thin Films

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Journal of Materials Science & Technology 2013年第9期29卷 788-794页

作者： k.Mensah-Darkwa r.k.Gupta D.kumar Engineering research Center of revolutionizing Metallic Biomaterials Department of Mechanical Engineering North Carolina A & T State University Department of Chemistry Pittsburg State University

Magnesium(Mg)-hydroxyapatite(Ca10(PO4)6(OH)2,abbreviated as HA) composite films have been grown on Mg plates using a pulsed laser deposition *** property measurements and analysis have indicated that hardness and Young’s modulus of nMge(100e n)HA composite coatings increase with Mg content in the coatings and reach a maximum at a 70Mge 30HA composition.n and 100e n in the nMge(100e n)HA represent the relative number of laser pulses impinging on Mg and HA targets,*** current potentiodynamic polarization studies have shown that the corrosion of Mg plate(control) decreases with an increase in the HA ratio in the composite *** example,the corrosion current density of Mg plate reduces by w350 times after coating the Mg plate with 10Mge 90HA composite *** reduction in corrosion current density of Mg plates was also accompanied by a positive shift in the corrosion potential(w6%) due to this *** mechanism behind the reduction in corrosion behavior of Mg plates due to nMge(100e n) HA composite coatings has been understood by electrochemical impedance spectroscopy.

关键词： Magnesium Hydroxyapatite Scanning electron microscopy Pulsed laser deposition Corrosion impedance spectroscopy

Magnetic and flotation studies of banded hematite quartzite (BHQ) ore for the production of pellet grade concentrate

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international Journal of Minerals,Metallurgy and Materials 2010年第6期17卷 675-682页

作者： B. Das B.k.Mishra S. Prakash S.k.Das P.S.r.reddy S.i.Angadi institute of Minerals and Materials Technology Council of Scientific & Industrial Research (CSIR)

To identify and establish beneficiation techniques for banded hematite quartzite （BHQ） iron ore, a comprehensive research on BHQ ore treatment was carried out. The BHQ ore was assayed as 38.9wt% Fe, 42.5wt% SiO2, and 1.0wt% Al2O3. in this ore, hematite and quartz are present as the major mineral phases where goethite, martite, and magnetite are present in small amounts. The liberation of hematite particles can be enhanced to about 82% by reducing the particle size to below 63 μm. The rejection of silica particles can be obtained by magnetic and flotation separation techniques. Overall, the BHQ ore can be enriched to 65.3wt% Fe at 61.9% iron recovery. A flowsheet has been suggested for the commercial exploitation of the BHQ ore.

关键词： hematite beneficiation magnetic separation flotation pelletizing

SEMi-TiErED HOUSiNG FOr LATEriTE EArth SLOPiNG LANDS-A SUSTAiNABLE SOLUTiON WiTH ALTErNATiVE MATEriALS AND METHODS

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Journal of Green Building 2018年第1期13卷 56-72页

作者： M.T.r.Jayasinghe C.Jayasinghe k.k.G.k.D.kariyawasam L.i.N.De Silva Department of Civil Engineering University of Moratuwa-Sri Lanka University of Moratuwa-Sri Lanka

increased demand for affordable housing and the limited availability of flat terrain for its construction are two major problems facing the provision of houses of acceptable quality in many countries around the *** is limited research integrating the utilization of a stepped approach to sloping terrain with appropriate housing models to minimize slope instability *** paper introduces a new semi-tiered housing model where the footprint of the house is located on tiers prepared with short vertical cuts of *** vertical cuts are found to be stable with laterite soil which is a commonly available type of soil in the *** excess soil generated from cut material was transformed into cement stabilized rammed earth,which is a cost effective material with low embodied *** is an ideal candidate for the construction of retaining walls and foundations,and such applications are demonstrated with adequate ***,many other types of sustainable building materials are highlighted with a case study of this housing model in a scheme of 13 housing units in Sri *** attention to detail required in construction and the applicability of alternative building materials and methods to improve the sustainability of such houses have been discussed in *** semi-tiered houses have the potential to address many of the current construction challenges.

关键词： stepped housing stabilized earth micro concrete roofing tiles sustainable construction

Power Quality improvement of Distribution Network Using BESS and Capacitor Bank

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Journal of Modern Power Systems and Clean Energy 2021年第3期9卷 625-632页

作者： F.r.islam A.Lallu k.A.Mamun k.Prakash N.k.roy University of Sunshine Coast Sip-py DownsAustralia University of South Pacific SuvaFiji kJiulna University of Engineering and Technology KhulnaBangladesh

The power demand around the world is increasing *** aging distribution network architectures are used by the existing utility companies to deliver power to the consumers,which significantly affects the reliability,stability and quality of the delivered *** techniques such as compensation devices have been used by power system engineers and researchers to maintain the quality of power transmitted to end *** this paper,wattage and volt-amp reactive(VAr)planning scheme has been proposed by using the combination of battery energy storage systems(BESS)and compensators to deal with the vulnerability of networks to voltage drop and system *** cost-effective combination of BESS and shunt capacitor bank will then be analyzed to indicate the benefit of the proposed scheme.

关键词： Battery energy storage system(BESS) shunt capacitor bank reliability stability quality volt-amp reactive(VAr)planning distribution network