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Enhanced entropy generation and heat transfer characteristics of magnetic nano-encapsulated p.ase 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 p.ase 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 p.ase change material(NEpCM) radiation stefan number heat capacity ratio entropy generation

Wind energy feasibility and wind turbine selection studies for the city surat,India

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Clean Energy 2024年第3期8卷 166-173页

作者： Arshi Banu p s Maanat Bhadani Hindustan institute of technology and science ChennaiIndia The Doon school UttarakhandDehradunIndia

Wind energy represents a clean,abundant and cost-effective power source,fostering job growth and environmental *** wind energy harnesses several gigawatts today,its availability hinges on diverse factors,with geographical location standing *** turbines,with varying capacity ranges,saturate the *** site-specific suitability and matching the appropriate turbine to meet specific requirements are of paramount *** study aims to assess the feasibility of wind energy in surat,Gujarat,India and select an optimal small commercial turbine for residential *** research involves rayleigh and Weibull probability distribution functions based on yearlong velocity *** distributions are fitted with actual data,revealing the most probable velocity(v_(mf)=3 m/s)and velocity at maximum power(v_(p.ax)=5 m/s).The power availability of the site has been assessed as 42.6 W/m^(2)using both graphical and analytical *** commercial turbines have been shortlisted based on on-site power criteria and their specifications are evaluated against site power availability.A comparative analysis culminates in identifying the most suitable turbine for the *** best suitable turbine for the site with an annual energy yield of 8 MW has been suggested amongst selected turbines for small-scale residential applications.

关键词： site feasibility wind energy commercial wind turbine probability distribution function rated power

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

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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,p.ase 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 disp.ay 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 disp.ays 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

Temperature-dependent thermal conductivity and fuel performance of UN-UO_(2) and UN-X-UO_(2)(X=Mo,W)composite nuclear fuels by finite element modeling

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Journal of Materiomics 2024年第4期10卷 937-946页

作者： Faris sweidan Diogo ribeiro Costa Huan Liu pär Olsson KTH royal institute of technology Nuclear EngineeringStockholm10691Sweden Westinghouse Electric sweden AB Västerås72163Sweden

The temperature-dependent effective thermal conductivity of UN-X-UO_(2)(X=Mo,W)nuclear fuel composite was *** the experimental design,the thermal conductivity was calculated using Finite Element Modeling(FEM),and compared with analytical models for 10%,30%,50%,and 70%(in mass)uncoated/coated UN microspheres in a UO2 *** FEM results show an increase in the fuel thermal conductivity as the mass fraction of the UN microspheres increases from 1.2 to 4.6 times the UO2 reference at 2,000 *** results from analytical models agree with the thermal conductivity estimated by *** results also show that Mo and W coatings have similar thermal behaviors,and the coating thickness influences the thermal conductivity of the *** higher weight fractions,the thermal conductivity of the fuel composite at room temperature is substantially influenced by the high thermal conductivity coatings approaching that of ***,the thermal conductivity from FEM was used in the fuel thermal performance evaluation during LWr normal operation to calculate the maximum centerline *** results show a significant decrease in the fuel maximum centerline temperature ranging from−94 K for 10% UN to−414 K for 70%(in mass)UN compared to UO2 under the same operating conditions.

关键词： Accident tolerant fuel UN-X-UO_(2) Composite nuclear fuel Thermal conductivity Finite element modeling Thermal performance

Cryogenic and conventional milling of AZ91 magnesium alloy

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Journal of Magnesium and Alloys 2024年第6期12卷 2503-2519页

作者： Vikas Marakini srinivasa pai p Gururaj Bolar Bhaskara p.achar Department of Mechanical engineer.ng Nitte(Deemed to be University)NMAM Institute of Technology(NMAMIT)Nitte 574110India Department of Mechanical and Industrial engineer.ng Manipal Institute of TechnologyManipal Academy of Higher EducationManipal 576104India

Use of magnesium is the need of the hour due to its low density as well as its high strength-to-weight and stiffness-to-weight ratio *** study focuses on the effectiveness of liquid nitrogen(LN_(2))assisted cryogenic machining on the surface integrity(sI)characteristics of AZ91 magnesium *** milling using uncoated carbide inserts have been performed under liquid nitrogen(LN_(2))assisted cryogenic condition and compared with conventional(dry)*** are performed using machining parameters in terms of cutting speeds of 325,475,625 m/min,feed rates of 0.05,0.1,0.15 mm/teeth and depth of cuts of 0.5,1,1.5 mm *** significant surface integrity characteristics such as surface roughness,microhardness,microstructure,and residual stresses have been *** of sI characteristics with respect to milling parameters have been identified using statistical technique such as ANOVA and signal-to-noise(s/N)ratio ***,the multi criteria decision making(MCDM)techniques such as additive ratio assessment method(ArAs)and complex proportional assessment(COp.as)have been utilized to identify the optimal conditions for milling AZ91 magnesium alloy under both dry and cryogenic *** of LN_(2)during machining,resulted in reduction in machining temperature by upto 29%with a temperature drop from 251.2℃under dry condition to 178.5℃in cryogenic *** showed the advantage of performing cryogenic milling in improving the surface integrity to a significant *** machining considerably minimized the roughness by upto 28%and maximised the microhardness by upto 23%,when compared to dry *** speed has caused significant impact on surface roughness(95.33%-dry,92.92%-cryogenic)and surface microhardness(80.33%-dry,82.15%-cryogenic).Due to the reduction in machining temperature,cryogenic condition resulted in compressive residual stresses(maximumσ║=-113 Mpa)on the alloy *** indicate no

关键词： Magnesium alloy Cryogenic machining roughness Microhardness Microstructure residual stress Multi criteria decision making

Temperature and structure measurements of heavy-ion-heated diamond using in situ X-ray diagnostics

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Matter and radiation at Extremes 2024年第4期9卷 80-89页

作者： J.Lutgert p.Hesselbach M.schorner V.Bagnoud r.Belikov p.Drechsel B.Heuser O.sHumphries p.Katrik B.Lindqvist C.Qu r.redmer D.riley G.schaumann s.schumacher A.Tauschwitz D.Varentsov K.Weyrich X.Yu B.Zielbauer Zs.Major p.Neumayer D.Kraus institut fur physik Universitat RostockAlbert-Einstein-Str.2318059 RostockGermany GsI Helmholtzzentrum fur schwerionenforschung Planckstr.164291 DarmstadtGermany institut für Angewandte physik Goethe-Universität Frankfurt am MainMax-von-Laue-Str.160438 Frankfurt am MainGermany institut fur Geowissenschaften Goethe-Universitat Frankfurt am MainAltenhoferallee 160438 Frankfurt am MainGermany Helmholtz-Zentrum Dresden-rossendorf Bautzner Landstr.40001328 DresdenGermany Europ.an XFEL GmbH Holzkoppel 422869 SchenefeldGermany Centre for p.asma physics School of Mathematics and PhysicsQueen’s University BelfastUniversity RoadBelfast BT71NNUnited Kingdom institut für Kernphysik Technische Universität DarmstadtSchlossgartenstr.964289 DarmstadtGermany state Key Laboratory of Nuclear physics and technology Institute of Heavy Ion PhysicsPeking UniversityBeijing 100871China Helmholtz institut Jena Frobelstieg 307743 JenaGermany

We present in situ measurements of spectrally resolved X-ray scattering and X-ray diffraction from monocrystalline diamond samples heatedwith an intense pulse of heavy *** this way,we determine the samples’heating dynamics and their microscopic and macroscopic structuralintegrity over a timespan of several *** the ratio of elastic to inelastic scattering with state-of-the-art density functionaltheory molecular dynamics simulations allows the inference of average temperatures around 1300 K,in agreement with predictions fromstopping power *** simultaneous diffraction measurements show no hints of any volumetric graphitization of the material,butdo indicate the onset of fracture in the diamond *** experiments pave the way for future studies at the Facility for Antiproton andIon research,where a substantially increased intensity of the heavy ion beam will be available.

关键词： heated intense structure

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 engineer.ng 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

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 engineer.ng 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 p.antom cooling coolant injection net heat flux reduction aerodynamic performance

An Efficient Approach to Escalate the speed of Training Convolution Neural Networks

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china communications 2024年第2期21卷 258-269页

作者： p pabitha Anusha Jayasimhan Department of Computer technology Anna UniversityMadras Institute of Technology CampusChennai 600044India

Deep neural networks excel at image identification and computer vision applications such as visual product search, facial recognition, medical image analysis, object detection, semantic segmentation,instance segmentation, and many others. In image and video recognition applications, convolutional neural networks(CNNs) are widely employed. These networks provide better performance but at a higher cost of computation. With the advent of big data, the growing scale of datasets has made processing and model training a time-consuming operation, resulting in longer training times. Moreover, these large scale datasets contain redundant data points that have minimum impact on the final outcome of the model. To address these issues, an accelerated CNN system is proposed for speeding up training by eliminating the noncritical data points during training alongwith a model compression method. Furthermore, the identification of the critical input data is performed by aggregating the data points at two levels of granularity which are used for evaluating the impact on the model *** experiments are conducted using the proposed method on CIFAr-10 dataset on resNet models giving a 40% reduction in number of FLOps with a degradation of just 0.11% accuracy.

关键词： CNN deep learning image classification model compression