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Frontiers of Materials Science 2013年第3期7卷 285-294页

作者： M. JAMESH T. S. n. SAnkARA nARAYAnAn Paul k. CHU II Song PARk Min Ho lee national Metallurgical Laboratory Madras Centre CSIR Madras Complex Taramani Chennai 600 113 India Department of Physics and Material Science City University of Hong Kong Tat Chee Avenue Kowloon Hong Kong China School of Physics University of Sydney NSW 2006 Australia Department of Dental Biomaterials School of Dentistry Chonbuk National University Jeonju 561-756 South Korea

The effect of surface mechanical attrition treatment （SMAT） of commercially pure titanium （CP-Ti） using 8 mm O alumina balls was studied. SMAT induced plastic deformation, increased the surface roughness, reduced the grain size and decreased the contact angle （from 64° to 43°） with a corresponding increase in surface energy （from 32 to 53 mJ/m2）. Untreated CP-Ti and those treateded using alumina bails for 900 s reveals no apatite growth until the 28th day of immersion whereas those treated for 1800 and 2700 s exhibit apatite growth In selective areas and the extent of growth is increased with increase in immersion time an SBF; The study reveals that SMAT using alumina balls is beneficial in imparting the desired surface Cheracteristics, provided the surface contamination is limited, which would otherwise decrease the apatite forming ability.

关键词： kEYWORDS: nanostructured material surface modification sca.ning electron micro-scopy (SEM) surface mechanical attrition treatment(SMAT)

Investigation into machining performance of microstructurally engineered in-situ particle reinforced magnesium matrix composite

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Journal of Magnesium and Alloys 2023年第3期11卷 916-935页

作者： S.k.Sahoo B.n.Sahoo S.k.Panigrahi Department of Mechanical Engineering Indian Institute of Technology MadrasChennai 600036India Applied Magnesium Research Group Center of Excellence in Materials and Manufacturing for Futuristic MobilityIndian Institute of Technology MadrasChennai 600036India Department of Mechanical Engineering Sardar Vallabhbhai National Institute of TechnologySurat 395007India

Magnesium and magnesium in-situ composites have significant potential in the application of design and manufacturing for automotive and aerospace industries because of their high specific strength and reduced fuel *** there are many challenges for machining of Mg based alloys and composites because of the high tendency of fire and *** challenges can be minimized through microstructural *** this present study,the machining performances of AZ91 Mg alloy and in-situ hybrid TiC+TiB_(2)reinforced AZ91 metal matrix composite was *** effectβ-Mg_(17)Al_(12)phases and grain refinement with and without in-situ particles on machinability were studied through microstructural engineering via aging and friction stir *** end milling operation was carried out at different cutting speeds ranging from 25 mm/min to 90 mm/min under dry environment by using an AlTin-coated tungsten carbide *** optimum cutting speed for machining was found to be 75 mm/min based on the surface roughness values of all conditioned *** base material with dendritic microstructure was found to have poor machinability in terms of inadequate surface finish and edge-burrs *** combined effect of in-situ TiC+TiB_(2)particles addition and grain refinement enhanced the machining performance of the material with superior surface finish,negligible edge-burr formation and better tool wear *** influence of in-situ TiC+TiB_(2)particles,β-Mg_(17)Al_(12)phases and grain refinement on machining characteristics are explained based on the tool wear mechanisms,chip behavior and machining induced affected zone.

关键词： Magnesium In-situ composite End-milling Tool wear Chip morphology

Efficient blue perovskite LEDs from quantum confined structures

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Science China Chemistry 2020年第1期63卷 3-4页

作者： Mahesh k.Gangishetty Daniel n.Congreve Rowland Institute Harvard University

Lead halide perovskites have been leading the optoelectronic field for the last several years,with exceptional progress in photovoltaics and rapid improvement in light emitting diodes(LEDs).LEDs are limited by outcoupling and waveguiding to approximately 20%external quantum efficiency(EQE),and infrared and green perovskite LEDs have already reached this threshold[1-3].For most applications,however,blue light is also required,and blue perovskite LEDs have been left behind,with a maximum EQE of 5.7%at 480 nm[4],and〜2%at wavelengths less than 470 nm[5].These lower efficiencies are due to both challenges inherent in blue(i.e.,wide band gap)materials as well as stability and defect problems specific to blue perovskites.

关键词： optoelectronic quantum perovskite

Combustion synthesis and luminescence characteristic of rare earth activated LiCaBO_3

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Journal of Rare Earths 2012年第10期30卷 1005-1008页

作者： n.S. Bajaj S.k. Omanwar Department of Physics SGB Amravati University Amravati-444602 (M.S.)

Lithium calcium borate （LiCaBO3） polycrystalline thermoluminescence （TL） phosphor doped with rare earth （Tb3＋ and Dy3＋） elements was synthesized by novel solution combustion synthesis. The reaction produced very stable crystalline LiCaBO3：D（D=Tb3＋ and Dy3＋） phosphors. These rare earth doped phosphors material showed maximum TL sensitivity with favorable glow curve shape. TL glow curve of X-ray irradiated that LiCaBO3：Tb3＋ and LiCaBO3：Dy3＋ samples showed two major well-separated glow peaks. The TL sensitivity of these phosphors to X-ray radiation was comparable with that of TLD-100（Harshaw）. Photoluminescence spectra of LiCaBO3：Tb3＋ and LiCaBO3：Dy3＋ showed the characteristic Tb3＋ and Dy3＋ peaks respectively. TL response to X-ray radiation dose was linear up to 25 Gy.

关键词： luminescence LiCaBO3 combustion synthesis rare earths kinetics

Aldo-keto synthesis effect on Eu^(3+) fluorescence in YBO3 compared with solid state diffusion

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Journal of Rare Earths 2015年第5期33卷 486-490页

作者： k.A.koparkar n.S.Bajaj S.k.Omanwar Department of Physics Sant Gadge Baba Amravati University

The red-orange emitting phosphor YBO3：Eu3＋was prepared by aldo-keto method and solid state diffusion. Aldo-keto method implied to decrease the processing time and heating temperature. The red-orange emitting phosphor was characterized by X-ray diffraction （XRD）, scanning electron microscopy （SEM）, as well as emission and excitation photoluminescence spectra re-corded at room temperature. The result of aldo-keto method showed that the phosphor YBO3：Eu3＋could be obtained at 900 °C in less time^60%as compared to solid state diffusion （SSD）. The material showed that the strongest emission peak at 595 nm under excitation at 233 nm was only due to forced magnetic dipole 5D0→7F1 transition of Eu3＋ions. Significantly, the emission inten-sity of YBO3：Eu3＋phosphor prepared by aldo-keto method was relatively higher as compared to that obtained by the solid state diffusion.

关键词： aldo-keto method yttria europium optical materials photoluminescence (PL) rare earths

Drop weight impact analysis of GFRP tubes with hollow glass particle-filled matrix

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Defence Technology（防务技术） 2023年第11期29卷 1-9页

作者： Daniel Paul R.Velmurugan n.k.Gupta Department of Aerospace Engineering Indian Institute of Technology MadrasChennaiIndia Department of Applied Mechanics Indian Institute of Technology DelhiNew DelhiIndia

Protecting occupants or payloads in crashes and blasts is of utmost importance in both moving and immobile *** way of achieving this is by using a sacrificial energy *** tubes have been studied as potential energy absorbers due to their ability to fail progressively under axial *** this study,the energy absorption capability of these tubes is enhanced by adding hollow glass particles to the ***-weight tests are performed on composite tubes,and a digital image correlation(DIC)-based technique is used to capture their load-displacement *** eliminates the use of electronic data acquisition systems,load cells,and *** load-displacement curves of the tubes are obtained from the DIC-based technique and examined to understand their crushing *** the mean crush load shows a drop,an increase in crush length is *** specific energy absorbed by the tubes improves with an increase in GMB volume *** addition of 0.1,0.2,0.3 and 0.4 vol fractions of GMB results in the specific energy absorption increasing by6.6%,14.7%,24%and 36.6%,respectively,compared to neat glass fibre-epoxy *** examination of the tubes and comparison with tubes subject to quasi-static compression is also performed.

关键词： Composite tubes Syntactic foam Impact Axial compression Digital image correlation

Models and form factors for stand volume estimation in natural forest ecosystems: a case study of katarniaghat Wildlife Sanctuary (kGWS), Bahraich District, India

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Journal of Forestry Research 2013年第2期24卷 217-226页

作者： V. A. J Adekunle k. n. nair A. k. Srivastava n. k. Singh Federal University of Technology Dept of Forestry & Wood Technology national Botanical Research Institute (Council for Scientific & Industrial Research) Plant Diversity Systematics & Herbarium Division Rana Pratap Marg Department of Forests Sidhauli Forest Division

In view of the difficulties in stand volume estimation in natural forests, we derived real form factors and models for volume estimation in these types of forest ecosystems, using katarniaghat Wildlife Sanctuary as a case study. Tree growth data were obtained for all trees （dbh 〉10 cm） in 4 plots （25 × 25 m） randomly located in each of three strata selected in the forest. The form factor calculated for the stand was 0.42 and a range of 0.42 0.57 was estimated for selected species （density 〉10）. The parameters of model variables were consistent with general growth trends of trees and each was statistically significant. There was no significant difference （p〉0.05） between the observed and predicted volumes for all models and there was very high correlation between observed and predicted volumes. The output of the performance statistics and the logical signs of the regression coefficients of the models demonstrated that they are useful for volume estimation with minimal error. Plotting the biases with respect to considerable regressor variables showed no meaningful and evident trend of bias values along with the independent variables. This showed that the models did not violate regression assumptions and there were no heteroscedacity or multiculnarity problems. We recommend use of the form factors and models in this ecosystem and in similar ones for stand and tree volume estimation.

关键词： natural forest tree volume Estimation biodiversity tree height forest inventory

Structural and mass transport properties of liquid ytterbium in the temperature range 1123 k–1473 k

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Chinese Physics B 2023年第6期32卷 481-488页

作者： D D Satikunvar n k Bhatt B Y Thakore Department of Physics Sardar Patel UniversityVallabh VidyanagarGujarat 388120India Department of Physics Maharaja Krishnakumarsinhji Bhavnagar UniversityBhavnagarGujarat 364001India

We have studied the structural and atomic transport properties of liquid f-shell Yb in the temperature range 1123 k–1473 k. Pair interactions between atoms are derived using a local pseudopotential. The potential parameters are fitted to the phonon dispersion curve at room temperature. The local pseudopotential used in the present study is computationally more efficient with only three parameters, and it is found to be transferable to the liquid phase without changing the *** the various computed properties agree with reported theoretical and experimental findings, the adopted fitting scheme is justified. As a significant outcome of the study, we find that(i) the melting in Yb is governed by the Lindemann's law,(ii)the mass transport mechanism obeys the Arrhenius law,(iii) the role of the three-particle correlation function in deriving the velocity autocorrelation function is small,(iv) the mean-square atomic displacement is more sensitive to the choice of interaction potential than the other bulk properties, and(v) liquid Yb does not show liquid–liquid phase transition within the studied temperature range. Further, due to the good description of the structural and mass transport properties, we propose that Yb remains divalent at reduced density.

关键词： transport properties pseudopotential single-particle dynamics ytterbium

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

An Integrated Die Casting Design System

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厦门大学学报（自然科学版） 2002年第S1期41卷 208-209页

作者： Y k Woon k S lee Dept. of Mechanical and Production Engineering National University of SingaporeDept. of Mechanical and Production Engineering National University of Singapore SingaporeSingapore

Die casting process is one of the prime options for m anufacturing precisely dimensioned, sharply defined metal parts. The design of d ie casting dies comprises several stages and entails a large amount of time. Tra ditionally, the different stages of the die design were not integrated but exist as separate entities. Moreover, recurring modifications or even redesigns are r equired due to the complexity in achieving an accurate initial die design. As a result, die design is usually time-consuming and costly with respect to resourc es. The die casting industry will greatly benefit if proper application software are developed that integrates the different die design stages and allows editin g of die design as and when needed. Hence it is imperative to create an integrat ed die design system that shortens the die design time. This paper presents a research that establishes a prototype of an integrated die design system. It is developed using the commercial SolidWorks CAD system and n amed DiWorks. The aim of building the system on a commercial CAD system is to ut ilise the resources and features of the CAD system to speed up the die design pr ocess. DiWorks consists of six distinct modules: Project Manager, Cavity Insert Builder, Gating System Constructor, Die Base Designer, Ejector System Constructo r and Standard Components Library. Through these six modules, the die designer c an create a complete die casting die beginning from a product part model. It is a user-friendly system that allows both experienced and novice die designers to easily accomplish the task of die design. The practical goal of this research is twofold: to develop a system that integra tes the die design process and at the same time facilitates the editing of d ie design during or after the course of the design process. The research approac h includes (i) parametric design, (ii) feature-based design (iii) system modeli ng and implementation. Parametric design deals with variable dimensions as cont

关键词： integrated die design system parametric design feature-based design