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Emission colour tuning in kLnF_(4):Yb^(3+),Er^(3+)/Ho^(3+)phosphor

Journal of Rare Earths 2024年第1期42卷 57-65,I0002页

作者： Janani k Gayathri E Vijayatha V Ramasubramanian s Thiyagarajan p Department of science and Humanities Nehru Institute of TechnologyKaliapuramThirumalayampalayamCoimbatoreIndia Department of sciences Amrita School of Physical SciencesAmrita Vishwa VidyapeethamCoimbatoreIndia Department of physics Anna UniversityChennaiIndia

kLnF_(4):Yb^(3+),Er^(3+)/Ho^(3+)(Ln=Y,Yb,Gd)phosphors were prepared by solid-state reaction *** each of the Yb^(3+)/Er^(3+)and Yb^(3+)/Ho^(3+)co-doped phosphors independently,phase confirmation and morphological examination were accomplished using the X-ray diffraction technique and scanning electron microscope analysis.X-ray photoelectron spectroscopy analysis shows the charge state and existence of lanthanides and *** luminescence emissions of green and red colour were detected for the synthesized *** changes in the upconverted emission intensities and colour output pertaining to the change of the lanthanide host matrix along with dopants were investigated for the prepared *** the upconversion luminescence,erbium-doped samples exhibit a predominance of red emission while holmium-doped samples display a prevalence of green *** rare-earth Er/Ho doped kYbF4shows strong red emission compared to other ***_(4):Yb,Er/Ho exhibits relatively significant green upconve rsion emissions,while Yb,Er-doped kGdF_(4)host displays a 10-fold increase in green/red emission ratio with an increase in the input power of 20-780 *** photoluminescence studies and decay curve analysis were carried out using UV light excitation for the developed phosphors.A higher lifetime of 2.2 ms was measured for the downshifting red emission in the Ho doped kYbF_(4)*** study suggests a potential for colour tunability in the upconversion and downshifting emissions through host modifications to the fluoride phosphor.

关键词： Rare earths Energy transfer upconversion Downshifting Colour coordinates

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Turbine passage secondary Flow Dynamics and Endwall Heat Transfer Under Different Inflow Turbulence

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Journal of Harbin Institute of Technology(New series) 2024年第3期31卷 51-62页

作者： Arjun k s Tide p s Biju N Division of Mechanical Engineering School of EngineeringCochin University of Science&TechnologyKalamassery 682022India

This study presents endwall hydrodynamics and heat transfer in a linear turbine cascade at Re 5×105 at low and high intensities of *** are numerically predicted using the standard ssT model and Reθ-γtransition model as well as using the high-resolution LEs *** major secondary flow components,comprising the horseshoe,corner,and passage vortices are recognized and the impact on heat or mass transfer is *** complicated behavior of turbine passage secondary flow generation and establishment are impacted by the perspective of boundary layer attributes and inflow *** passage vortex concerning the latest big leading-edge vane is generated by the enlargement of the circulation developed at the first instance adjacent to the pressure side becomes powerful and mixes with other vortex systems during its migration towards the suction *** study conclusions reveal that substantial enhancements are attained on the endwall surface,for the entire spanwise blade extension on the pressure surface,and in the highly 3-D region close to the endwall on the suction *** forecasted suction surface thermal exchange depicts great conformity with the measurement values and precisely reproduces the enhanced thermal exchange owing to the development and lateral distribution of the secondary flows along the midspan of the blade passage *** impacts of the different secondary flow structures on the endwall thermal exchange are described in depth.

关键词： turbine vane heat transfer endwall turbulence secondary flow

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Optimum profiles of Endwall Contouring for Enhanced Net Heat Flux Reduction and Aerodynamic performance

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Journal of Harbin Institute of Technology(New series) 2024年第2期31卷 80-92页

作者： Arjun k s Tide p s Biju N Division of Mechanical Engineering School of EngineeringCochin University of Science&TechnologyKalamassery 682022India

successfully utilized non-axisymmetric endwalls to enhance turbine efficiencies(aerodynamic and turbine inlet temperatures)by controlling the characteristics of the secondary flow in a blade *** is accomplished by steady-state numerical hydrodynamics and deep knowledge of the field of *** of the interaction between mainstream and purge flow contributing supplementary losses in the stage,non-axisymmetric endwalls are highly susceptible to the inception of purge flow exit compared to the flat and any advantage rapidly *** conclusions reveal that the supreme endwall pattern could yield a lowering of the gross pressure loss at the design stage and is related to the size of the top-loss location being productively *** has led to diminished global thermal exchange lowered in the passage of the vane *** reverse flow adjacent to the suction side corner of the endwall is migrated farther from the vane surface,as the deviated pressure spread on the endwall accelerates the flow and progresses the reverse flow core still *** depleted association between the tornado-like vortex and the corner vortex adjacent to the suction side corner of the endwall is the dominant mechanism of control in the contoured end *** this publication,we show that the non-axisymmetric endwall contouring by selective numerical shape change method at most prominent locations is advantageous in lowering the thermal load in turbines to augment the net heat flux reduction as well as the aerodynamic performance using multi-objective optimization.

关键词： endwall contouring turbine vane heat transfer phantom cooling coolant injection net heat flux reduction aerodynamic performance

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Enhanced entropy generation and heat transfer characteristics of magnetic nano-encapsulated phase change materials in latent heat thermal energy storage systems

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Applied Mathematics and Mechanics(English Edition) 2024年第6期45卷 1051-1070页

作者： p.s.REDDY p.sREEDEVI Department of Mathematics Rajeev Gandhi Memorial College of Engineering and TechnologyNandyal 518501India

The objective of the current study is to investigate the importance of entropy generation and thermal radiation on the patterns of velocity,isentropic lines,and temperature contours within a thermal energy storage device filled with magnetic nanoencapsulated phase change materials(NEpCMs).The versatile finite element method(FEM)is implemented to numerically solve the governing *** effects of various parameters,including the viscosity parameter,ranging from 1 to 3,the thermal conductivity parameter,ranging from 1 to 3,the Rayleigh parameter,ranging from 102 to 3×10^(2),the radiation number,ranging from 0.1 to 0.5,the fusion temperature,ranging from 1.0 to 1.2,the volume fraction of NEpCMs,ranging from 2%to 6%,the stefan number,ranging from 1 to 5,the magnetic number,ranging from 0.1 to 0.5,and the irreversibility parameter,ranging from 0.1 to 0.5,are examined in detail on the temperature contours,isentropic lines,heat capacity ratio,and velocity ***,the heat transfer rates at both the cold and hot walls are analyzed,and the findings are presented *** results indicate that the time taken by the NEpCMs to transition from solid to liquid is prolonged inside the chamber region as the fusion temperatureθf ***,the contours of the heat capacity ratio Cr decrease with the increase in the stefan number ste.

关键词： volume fraction of nano-encapsulated phase change material(NEpCM) radiation stefan number heat capacity ratio entropy generation

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Understanding the corrosion and bio-corrosion behaviour of Magnesium composites – a critical review

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Journal of Magnesium and Alloys 2024年第3期12卷 890-939页

作者： prithivirajan sekar s.k.panigrahi Department of Mechanical Engineering Indian Institute of Technology MadrasChennai600036India Applied Magnesium Research Center Center of Excellence in Materials and Manufacturing for Futuristic MobilityIndian Institute of Technology MadrasChennai600036India

Realising the potential of Magnesium(Mg),several globally leading ventures have invested in the Mg industry,but their relatively poor corrosion resistance is a never ending saga till *** corrosion and bio-corrosion behaviour of Mg has gained research attention and still remains a hot topic in the application of automobile,aerospace and biomedical *** intrinsic high electrochemical nature of Mg limits their utilization in diverse *** scenario has prompted the development of Mg composites with an aim to achieve superior corrosion and bio-corrosion *** present review enlightens the influence of grain size(Gs),secondary phase,texture,type of matrix and reinforcement on the corrosion and bio-corrosion behaviour of Mg ***,the corrosion and bio-corrosion behaviour of Mg composites manufactured by primary and secondary processing routes are ***,the comprehensive corrosion and bio-corrosion mechanisms of these Mg composites are ***,the individual role of Gs,texture and corrosive medium on corrosion and bio-corrosion behaviour of Mg composites are clarified and *** challenges encountered,unanswered issues in this field are explained in detail and accordingly the scope for future research is *** review is presented from basic concrete background to advanced corrosion mechanisms with an aim of creating interest among the readers like students,researchers and industry experts from various research ***,the corrosion and bio-corrosion behaviour of Mg composites are critically reviewed for the first time to:(i)contribute to the body of knowledge,(ii)foster research and development,(iii)make breakthrough,and(iv)create life changing innovations in the field of Mg composite corrosion.

关键词： Corrosion Bio corrosion Magnesium alloys Magnesium composites Magnesium implants.

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Background removal from global auroral images:Data-driven dayglow modeling

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Earth and planetary physics 2024年第1期8卷 247-257页

作者： A.Ohma M.Madelaire k.M.Laundal J.p.Reistad s.M.Hatch s.Gasparini s.J.Walker Birkeland Centre for space science Department of Physics and TechnologyUniversity of BergenBergenNorway

Global images of auroras obtained by cameras on spacecraft are a key tool for studying the near-Earth ***,the cameras are sensitive not only to auroral emissions produced by precipitating particles,but also to dayglow emissions produced by photoelectrons induced by *** emissions and scattered sunlight can contribute to the background *** fully utilize such images in space science,background contamination must be removed to isolate the auroral *** we outline a data-driven approach to modeling the background intensity in multiple images by formulating linear inverse problems based on B-splines and spherical *** approach is robust,flexible,and iteratively deselects outliers,such as auroral *** final model is smooth across the terminator and accounts for slow temporal variations and large-scale asymmetries in the *** demonstrate the model by using the three far ultraviolet cameras on the Imager for Magnetopause-to-Aurora Global Exploration(IMAGE)*** method can be applied to historical missions and is relevant for upcoming missions,such as the solar wind Magnetosphere Ionosphere Link Explorer(sMILE)mission.

关键词： aurora dayglow modeling global auroral images far ultraviolet images dayglow removal

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A Hybrid Machine Learning Approach for Improvised QoE in Video services over 5G Wireless Networks

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Computers, Materials & Continua 2024年第3期78卷 3195-3213页

作者： k.B.Ajeyprasaath p.Vetrivelan school of Electronics Engineering Vellore Institute of TechnologyChennaiTamil Nadu600127India

Video streaming applications have grown considerably in recent *** a result,this becomes one of the most significant contributors to global internet *** to recent studies,the telecommunications industry loses millions of dollars due to poor video Quality of Experience(QoE)for *** the standard proposals for standardizing the quality of video streaming over internet service providers(Isps)is the Mean Opinion score(MOs).However,the accurate finding of QoE by MOs is subjective and laborious,and it varies depending on the user.A fully automated data analytics framework is required to reduce the inter-operator variability characteristic in QoE *** work addresses this concern by suggesting a novel hybrid XGBstackQoE analytical model using a two-level layering *** one combines multiple Machine Learning(ML)models via a layer one Hybrid *** ML models at level one are trained using the entire training data *** level two Hybrid XGBstackQoE-Model is fitted using the outputs(meta-features)of the layer one ML *** proposed model outperformed the conventional models,with an accuracy improvement of 4 to 5 percent,which is still higher than the current traditional *** proposed framework could significantly improve video QoE accuracy.

关键词： Hybrid XGBstackQoE-model machine learning MOs performance metrics QoE 5G video services

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MDCN:Modified Dense Convolution Network Based Disease Classification in Mango Leaves

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Computers, Materials & Continua 2024年第2期78卷 2511-2533页

作者： Chirag Chandrashekar k.p.Vijayakumar k.pradeep A.Balasundaram school of Computer science and Engineering Vellore Institute of Technology(VIT)ChennaiIndia Center for Cyber physical systems School of Computer Science and EngineeringVellore Institute of Technology(VIT)ChennaiIndia

The most widely farmed fruit in the world is *** the production and quality of the mangoes are hampered by many *** diseases need to be effectively controlled and ***,a quick and accurate diagnosis of the disorders is *** convolutional neural networks,renowned for their independence in feature extraction,have established their value in numerous detection and classification ***,it requires large training datasets and several parameters that need careful *** proposed Modified Dense Convolutional Network(MDCN)provides a successful classification scheme for plant diseases affecting mango *** model employs the strength of pre-trained networks and modifies them for the particular context of mango leaf diseases by incorporating transfer learning *** data loader also builds mini-batches for training the models to reduce training ***,optimization approaches help increase the overall model’s efficiency and lower computing *** employed on the MangoLeafBD Dataset consists of a total of 4,000 *** the experimental results,the proposed system is compared with existing techniques and it is clear that the proposed algorithm surpasses the existing algorithms by achieving high performance and overall throughput.

关键词： Leaf disease detection deep convolutional neural networks transfer learning optimization MangoLeafBD Dataset

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Excellent photoluminescence and electrochemical properties of sm^(3+) doped Ca_(2)Mgsi_(2)O_(7) nanophosphor:Display and electrochemical sensor applications

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Journal of Rare Earths 2024年第6期42卷 1046-1055,I0002页

作者： R.B.Basavaraj k.sureshkumar D.p.Aarti M.B.Madhusudana Reddy G.Nagaraju T.Ramakrishnappa G.R.Navyashree k.R.Venkatesha Babu k.s.Hemalatha Department of physics BMS Institute of Technology and ManagementBangalore560064India Department of Chemistry BMS Institute of Technology and ManagementBangalore560064India Department of Chemistry School of Applied SciencesREVA UniversityBangalore560064India Energy Materials ResearchLaboratory Department of ChemistrySiddaganga Institute of TechnologyTumakuru57203KarnatakaIndia school of physical sciences REVA UniversityBangalore560057Indi Department of physics Govt.Science CollegeBengaluru560001India Department of physics Maharani Science College for WomenMaharani Cluster UniversityBengaluru560001India

A series of orange-red light emitting Ca_(2)Mgsi_(2)O_(7):sm^(3+)nanopowders were fabricated via low-cost ecofriendly green combustion technique using Aloe vera gel as *** phase purity of the samples were confirmed by the powder X-ray diffraction(pXRD)*** single-phase tetragonal structure is observed from the pXRD results with no additional impurity *** band gap energy of the fabricated powders was estimated by diffuse reflectance spectra(DRs)and is found to be in the range of 4.01-5.98 eV.A high resolution scanning electron microscope(sEM)was used to study the morphological behaviour of the ***-like structures are observed from the sEM *** particle size was evaluated by transmission electron microscopy(TEM)and is found to be~50 *** interplanar distance is found to be 0.53 *** properties were systematically studied in *** phosphors are successfully excited at 403 nm NUV light,producing reddish-orange characteristic *** emission peaks are centered at 558(^(4)G_(5/2)→^(6)H_(5/2)),607(^(4)G_(5/2)→^(6)H_(7/2))and 645 nm(^(4)G_(5/2)→^(6)H_(9/2)),*** the observed peaks the red emanation(^(4)G_(5/2)→^(6)H_(7/2))is stronger than the orange emission(^(4)G_(5/2)→^(6)H_(5/2))in the current *** photoluminescent concentration quenching is noticed above 5 mol%sm^(3+)ion doping *** dipole-dipole interaction resulting in cross relaxation is found to be the principal cause of concentration quenching *** color features such as Commission Internationale de I’Eclairage(CIE)and correlated color temperature(CCT)were studied in *** optimized chromaticity coordinates were estimated to be(0.6363,0.3632),which fall in the reddish-orange *** average CCT value obtained is 3362 *** average color purity is found to be~82%.sm^(3+)incorporated Ca_(2)Mgsi_(2)O_(7) samples are possible contender for single white light generation commercial candidates owing to

关键词： Green combustion photoluminescence Orange-red emission Color purity sensors Rare earths

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Enhancing Multicriteria-Based Recommendations by Alleviating scalability and sparsity Issues Using Collaborative Denoising Autoencoder

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Computers, Materials & Continua 2024年第2期78卷 2269-2286页

作者： s.Abinaya k.Uttej kumar school of Computer science&Engineering Vellore Institute of TechnologyChennaiTamilnadu600127India

A Recommender system(Rs)is a crucial part of several firms,particularly those involved in *** conventional Rs,a user may only offer a single rating for an item-that is insufficient to perceive consumer ***,businesses in industries like e-learning and tourism enable customers to rate a product using a variety of factors to comprehend customers’*** the other hand,the collaborative filtering(CF)algorithm utilizing AutoEncoder(AE)is seen to be effective in identifying user-interested ***,the cost of these computations increases nonlinearly as the number of items and users *** triumph over the issues,a novel expanded stacked autoencoder(EsAE)with kernel Fuzzy C-Means Clustering(kFCM)technique is proposed with two *** the first phase of offline,the sparse multicriteria rating matrix is smoothened to a complete matrix by predicting the users’intact rating by the EsAE approach and users are clustered using the kFCM *** the next phase of online,the top-N recommendation prediction is made by the EsAE approach involving only the most similar user from multiple *** the EsAE_kFCM model upgrades the prediction accuracy of 98.2%in Top-N recommendation with a minimized recommendation generation *** experimental check on the Yahoo!Movies(YM)movie dataset and TripAdvisor(TA)travel dataset confirmed that the EsAE_kFCM model constantly outperforms conventional Rs algorithms on a variety of assessment measures.

关键词： Recommender systems multicriteria rating collaborative filtering sparsity issue scalability issue stacked-autoencoder kernel Fuzzy C-Means Clustering

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