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Journal of Rare Earths 2019年第9期37卷 916-923,I0001页

作者： M.s. Geetha H.n. shivananjaiah Vijaya Composite College Bangalore560 003India Government science College Nrupatunga RoadBangalore 560 001India

This paper reports a facile environmentally safe green combustion synthesis method of La3+doped CdO nanoparticles(nPs)using different concentrations of Aloe vera(A.V)gel as combustible *** crystallite size obtained using PXRD pattern is found to be 12-22 *** structural analysis was further analysed by Rietveld refinement *** X-ray photoelectron spectroscopy(XPs)analysis reveals the presence of two electronic states of CdO around 400 and 411 eV attributed to Cd 3 d3/2 and 3 d3/2,*** photoluminescence(PL)studies were carried upon 350 nm excitation *** PL emission spectra are found to have two prominent peaks centered at 410 and 510 nm and are attributed to 5D3→7F1 and 5D1→7F0 transitions,*** Commission International de l’Eclairage(CIE)chromaticity diagram reveals blue-green color *** correlation color temperature(CCT)value is found to be around^9793 *** obtained results suggest that the product is quite useful for cool light emitting diode applications when doping concentration is 2 mol%.

关键词： Green synthesis nanostructures Photoluminescence Judd-ofelt Rare earths CdO

Mat hematical modeling and analysis of innate and humoral immune responses to dengue infections

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International Journal of Biomathematics 2019年第7期12卷 95-110页

作者： sulanie Perera s.s.n.Perera Research and Development Center for Mathematical Modeling Faculty of ScienceUniversity of ColomboColombo 3Sri Lanka

Dengue is an acute arthropode-borne virus,belonging to the family ***,there are no vaccines or treatments available against *** it is important to understand the dynamics of dengue in order to control the *** this paper,we study the long-term dynamics of the model that is presented in[*** and ***,simulation model for dynamics of dengue with innate and humoral immune responses,*** Med.2018(2018)8798057,18 ***:10.1155/2018/8798057]which describes the interaction of virus with infected and uninfected cells in the presence of innate and humoral immune *** was found the model has three equilibria,namely:infection free equilibrium,no immune equilibrium and endemic equilibrium,then analyzed its stability *** analytical findings of each model have been exemplified by numerical *** the fact that intensity of dengue virus replication at early times of infection could determine clinical outcomes,it is important to understand the impact of innate immunity,which is believed to be the first line of defense against an invading *** this we carry out a simulation case study to investigate the importance of innate immune response on dengue virus dynamics.A comparison was done assurming that innate immunity was active;innate immunity was in quasi-steady state and innate immunity was inactive during the virus replication *** a further analysis of the qualitative behavior of the quasi-steady state,it was observed that innate immune response plays a pivotal role in dengue virus *** can change the dynamical behavior of the system and is essential for the virus clearance.

关键词： Dengue humoral inate equilibrium stability quasi-steady state

Combustion synthesis of Ce^(3+), Eu^(3+) and Dy^(3+) activated naCaPO_4 phosphors

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Journal of Rare Earths 2011年第6期29卷 527-535页

作者： K n shinde s J Dhoble Animesh Kumar Department of Physics RTM Nagpur University national Environmental Engineering Research Institute

The preparation of naCaPO4 doped with rare earth （RE） ions Ce3＋, Eu3＋ and Dy3＋ by combustion method was described. Under UV excitation （251 nm） of naCaPO4：Ce3＋ showsd emission （367 nm） in UV range. When naCaPO4：Dy3＋ phosphor was excited at 349 nm, the emission spectrum showed intense bands at 482 nm （blue） and 576 nm （yellow）. In Eu activated naCaPO4 phosphor, the emission spectrum showed a dominant peak at 594 nm （orange） while others were at 614 and 621 nm （red） when excited at 393 nm. The prepared phosphor was characterized by X-ray diffraction （XRD）, scanning electron microscope （sEM） and photoluminescence （PL） measurement. Thus, the photoluminescence behavior of naCaPO4：Ce3＋ was strongly suggested for scintillator. Likewise, Eu3＋ and Dy3＋ activated naCaPO4 phosphors were recommended for near-UV white light-emitting diodes （LEDs）.

关键词： combustion synthesis photoluminescence phosphor scintillator solid state lighting rare earths

The effect of K2siF6 on the MgH2 hydrogen storage properties

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Journal of Magnesium and Alloys 2020年第3期8卷 832-840页

作者： M.Ismail M.s.Yahya n.A.sazelee n.A.Ali F.A.Halim Yap n.s.Mustafa Energy storage Research Group Faculty of Ocean Engineering Technology and InformaticsUniversity Malaysia Terengganu21030 Kuala TerengganuMalaysia Faculty of Innovative Design and Technology Universiti Sultan Zainal AbidinGong Badak Campus21300 Kuala NerusTerengganuMalaysia

The catalytic effect of K2siF6 on MgH2 was first timely *** MgH2+5 wt.%K2siF6 was prepared via the ball milling *** catalyst had lessened the initial decomposition temperature by 134℃ and 48℃ as compared to both pristine and milled MgH2 samples,*** 2 minutes,4.5 wt.%of hydrogen was absorbed(250℃)by the doped composite,which was 0.8 wt.%higher than the milled ***,for the desorption kinetics(320℃,1 atm),the amount of desorbed hydrogen was increased by 2.4 wt.%and 2.3 wt.%for the first 10 and 20 ***,contracting volume and Johnson-Mehl-Avrami models were used to analyse the kinetics *** decomposition activation energy calculated based on Kissinger equation was 114 kJ/*** for the active species,Mg2si,MgF2 and KH were formed during the heating *** active species are speculated to be responsible for the improvement of the hydrogenation properties of the composite.

关键词： Catalytic effect Magnesium hydride Hydrogen storage sorption properties Contracting volume model

A novel Application of Multi-Resonant Dissipative Elastic Metahousing for Bearings

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Acta Mechanica solida sinica 2021年第4期34卷 449-465页

作者： Muhammad C.W.Lim n.s.Vyas Department of Architecture and Civil Engineering City University of Hong KongKowloonHong Kong SARChina Department of Mechanical Engineering Indian Institute of Technology KanpurKanpur208016India

Bearing as an important machine element is widely used for industrial and automotive *** certain operational speed,bearings induce disturbing vibrations and noises that affect machine service life,productivity and passenger comfort in case of vehicle *** elastic metamaterials have caught considerable attention of scientific community due to their effective medium properties and peculiar dynamic characteristics including frequency bandgaps that can be effectively applied to attenuate and control undesirable vibration and *** a substantial amount of theoretical work for effective medium characteristics and dynamic properties of acoustic/elastic metamaterials has been reported,the practical design and application of these composite structures for real-life engineering problems still remain *** present study intends to investigate a potential application of dissipative elastic metamaterials in controlling the bearing-generated vibration and noises over an ultrawide frequency *** study is based on a simple analytical model together with rigorous finite element numerical *** has been established that the dissipative characteristic of resonant system caused by larger material mismatch broadens the local resonance bandgaps beyond the bounding resonance frequency at the cost of wave *** order to achieve broadband vibration and noise control,multi-resonant composite structures are embedded inside the bearing housing in five different *** reported results revealed the presence of broadband wave attenuation zone distributed from 3 to 52 kHz with consideration of material *** bearing-generated vibration and noises lying inside the wave attenuation zone will be *** feasibility study provides a new concept for the design and application of acoustic/elastic metamaterials in the bearing industry to improve machine service life and to enhance productivity and passenger comfo

关键词： Bearing metahousing Dissipative elastic metamaterials Frequency Local resonance bandgap Vibration attenuation zone

nonplanar dust acoustic solitary and rogue waves in an ion beam plasma with superthermal electrons and ions

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Plasma science and Technology 2018年第7期20卷 64-71页

作者： nimardeep kaur kuldeep singh yashika ghai n s saini Guru nanak Dev University Amritsar-143005India

The propagation characteristics of dust acoustic solitary and rogue waves are investigated in an unmagnetized ion beam plasma with electrons and ions following kappa-type distribution in nonplanar geometry. The reductive perturbation method （RPM） is employed to derive the cylindrical/spherical Korteweg-de Vries （KdV） equation, which is further transformed into standard KdV equation by neglecting the geometrical effects. Using new stretching coordinates, nonlinear schrrdinger equation （nLsE） has been derived from the standard KdV equation to study the different order rational solutions of dust acoustic rogue waves （DARWs）. The impact of various physical parameters on the characteristics of dust acoustic solitary waves （DAsWs） is elaborated specifically in nonplanar geometry. Further, the effects of ion beam and superthermality of electrons/ions on the characteristics of DARWs are studied. The results obtained in the present investigation may be useful in comprehending a variety of phenomena in Earth＇s magnetosphere polar cap region where the presence of positive ion beam has been detected and also in other regions of space/astrophysical environments where dust along with superthermal electrons and ions exists.

关键词： dust acoustic ion beam kappa distribution rogue waves

Dust acoustic shock waves in magnetized dusty plasma

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Plasma science and Technology 2018年第7期20卷 27-34页

作者： yashika ghai nimardeep kaur kuldeep singh n s saini Department of Physics Guru Nanak Dev UniversityAmritsar-143005India

We have presented a theoretical study of the dust acoustic （DA） shock structures in a magnetized, electron depleted dusty plasma in the presence of two temperature superthermal ions. By deriving a Korteweg-de Vries-Burgers equation and studying its shock solution, we aim to highlight the effects of magnetic field and obliqueness on various properties of the DA shock structures in the presence of kappa-distributed two temperature ion population. The present model is motivated by the observations of Geotail spacecraft in the Earth＇s magnetotail and it is seen that the different physical parameters such as superthermality of the cold and hot ions, the cold to hot ion temperature ratio, the magnetic field strength, obliqueness and the dust kinematic viscosity greatly influence the dynamics of the shock structures so formed. The results suggest that the variation of superthermalities of the cold and hot ions have contrasting effects on both positive and negative polarity shock structures. Moreover, it is noted that the presence of the ambient magnetic field affects the dispersive properties of the medium and tends to make the shock structures less wide and more abrupt. The findings of present investigation may be useful in understanding the dynamics of shock waves in dusty plasma environments containing two temperature ions where the electrons are significantly depleted.

关键词： dusty plasma KdV-Burgers superthermal distribution Earth's magnetotail

Mechanical and microstructural variations in ECAP of Ti-6Al-4V alloy with equiaxed microstructure

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Rare Metals 2022年第8期41卷 2732-2738页

作者： Hamid Arabi Mostafa Ketabchi s.H.n.Alhosseini Mining and Metallurgical Engineering Department Amirkabir University of TechnologyTehran***Iran University Complex of Material and Manufacturing Malek Ashtar University of TechnologyTehran***Iran

The aim of this study is to investigate mechanical and microstructural variations of Ti-6 Al-4 V acquired through various equal channel angular pressing(ECAP)*** ECAP of Ti-6 Al-4 V alloy with the first equiaxed micros tructure was carried out by an isothermal warm and isothermal die *** A pressing carried out on cylindrical samples at 650℃.Mechanical and microstructural investigations were performed concerning Ti-6 Al-4 V in the first state after 2,4,and 8 *** microscopy(OM)investigation shows that alpha grain size increases and beta grain size decreases with the pass numbers *** phase content initially decreases in the first two ECAP *** results show that more equiaxed alpha grains are achieved after four ECAP *** of X-ray diffraction(XRD)analysis show that crystallite size decreases with the number of passes *** two ECAP passes,a vivid increase in mechanical strength is observed;however,the increment dramatically slows down by the increasing number of passes.

关键词： Ti-6Al-4V alloy Equal channel angular pressing Equiaxed microstructure Mechanical properties

A solids mixing rate correlation for small scale fluidized beds

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Particuology 2015年第4期13卷 55-64页

作者： s.Gorji-Kandi s.M.Alavi-Amleshi n.Mostoufi Department of Chemical Engineering Iran University of Science and Technology school of Chemical Engineering College of EngineeringUniversity of Tehran

A new first degree solids mixing rate is proposed to evaluate the mixing of solids in small scale Iluidized beds. Particle mixing experiments were carried out in a 2D fluidized bed with a cross-section of 0.02 m × 0.2 m and a height of Im. white and black particles with average diameters of 850 and 450 μm were used in our experiments. Image processing was used to measure the concentration of the tracers at different times. The effects of four representative operating parameters （superficial gas velocity, ratio of tracer particles to bed particles, tracer particle position, and particle size） on mixing are discussed with reference to the mixing index. We found that the Lacey index depends on the concentration of the tracers, The position of the tracers affects the initial mixing rate but not the final degree of mixing. However, the new mixing rate equation does not depend on the initial configuration of the particles because this situation is considered to be the initial condition. Using the data obtained in this work and that found in literature, an empirical correlation is proposed to evaluate the mixing rate constant as a function of dimensionless numbers （Archimedes, Reynolds, and Froude） in small scale fluidized beds. This correlation allows for an estimation of the mixing rate under different operating conditions and for the detection of the end point and/or the time of mixing.

关键词： Fluidized bed solids mixing Tracer Digital image processing Mixing index Mixing rate

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