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Particuology 2015年第5期13卷 72-81页

作者： K.Mahalik Y.K.Mohanty K.C.Biswal g.K.roy J.N.Sahu Department of Chemical Engineering Gandhi Institute of Engineering and Technology Department of Chemical Engineering National Institute of Technology Department of Chemical Engineering Faculty of EngineeringUniversity of Malaya Petroleum and Chemical Engineering Programme Area Faculty of EngineeringInstitut Teknologi Brunei(A Technology University)

The present paper describes the statistical modeling and optimization of a multistage gas-solid fluidized bed reactor for the control of hazardous pollutants in flue gas. In this work, we study the hydrodynamics of the pressure drop and minimum fluidization velocity. The hydrodynamics of a three-stage fluidized bed are then compared with those for a single-stage unit. It is observed that the total pressure drop over all stages of the three-stage fluidized bed is less than that of an identical single-stage system. However, the minimum fluidization velocity is higher in the single-stage unit. Under identical conditions, the minimum fluidization velocity is highest in the top bed, and lowest in the bottom bed. This signifies that the behavior of solids changes from a well-mixed flow to a plug-flow, with intermediate behavior in the middle bed.

关键词： Fluidized bed Multi-stage Pressure drop Minimum fluidization velocity Optimization

A novel microscale selective laser sintering(μ-SLS)process for the fabrication of microelectronic parts

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Microsystems & Nanoengineering 2019年第1期5卷 1-14页

作者： Nilabh K.roy Dipankar Behera Obehi g.Dibua Chee S.Foong Michael A.Cullinan Department of Mechanical Engineering The University of Texas at Austin204 E.Dean Keeton StAustinTX 78712USA NXP Semiconductors 6501W William Cannon DrAustinTX 78735US

One of the biggest challenges in microscale additive manufacturing is the production of three-dimensional,microscale metal parts with a high enough throughput to be relevant for commercial *** paper presents a new microscale additive manufacturing process called microscale selective laser sintering(μ-SLS)that can produce true 3D metal parts with sub-5μm resolution and a throughput of greater than 60mm^(3)/***μ-SLS,a layer of metal nanoparticle ink is first coated onto a substrate using a slot die coating *** ink is then dried to produce a uniform nanoparticle ***,the substrate is precisely positioned under an optical subsystem using a set of coarse and fine nanopositioning *** the optical subsystem,laser light that has been patterned using a digital micromirror array is used to heat and sinter the nanoparticles into the desired *** set of steps is then repeated to build up each layer of the 3D part in theμ-SLS ***,this new technology offers the potential to overcome many of the current limitations in microscale additive manufacturing of metals and become an important process in microelectronics packaging applications.

关键词： coating process additive

Hydrodynamics of three-phase fluidization of homogeneous ternary mixture in a conical conduit-Experimental and statistical analysis

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Chinese Journal of Chemical Engineering 2016年第10期24卷 1335-1343页

作者： R.K.Padhi D.T.K.Dora Y.K.Mohanty g.K.roy B.Sarangi Department of Chemical Engineering GIETGunupur-765 022RayagadaOdishaIndia Department of metallurgical Engineering ICITSarangaDhenkanalOdishaIndia

Hydrodynamics of conical fluidized bed differ from that of columnar beds by the fact that a velocity gradient exists along the axial direction of the *** gas–liquid–solid fluidized bed has emerged in recent years as one of the most promising devices for three-phase *** a device is of considerable industrial importance as evident from its wide applications in chemical,refining,petrochemical,biochemical processing,pharmaceutical and food *** explore this,a series of experiments have been carried out for homogeneous well-mixed ternary mixtures of dolomite of varying compositions in a three-phase conical fluidized *** hydrodynamic characteristics determined included the bed pressure drop,bed fluctuation and bed expansion *** single and combined effects of operating parameters such as superficial gas velocity,superficial liquid velocity,initial static bed height,average particle size and cone angle on the responses have been analyzed using response surface methodology(RSM).A 25 full factorial central composite experimental design has been *** of variance(ANOVA) showed a high coefficient of determination value and satisfactory prediction second-order regression models have been *** values of bed pressure drop,bed fluctuation and bed expansion ratios have been found to agree well with the developed correlations.

关键词： gas-liquid-solid fluidization Conical bed Bed pressure drop Bed fluctuation ratio and bed expansion ratio ANOVA

Adaptive Cell Segmentation and Tracking for Volumetric Confocal Microscopy Images of a Developing Plant Meristem

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Molecular Plant 2011年第5期4卷 922-931页

作者： Min Liu Anirban Chakrabortyt Damanpreet Singh Ram Kishor Yadav gopi Meenakshisundaram g. Venugopala Reddy Amit roy-Chowdhury Department of Electrical Engineering University of California Riverside CA USA Department of Computer Science University of California Irvine CA USA Department of Botany and Plant Sciences and Center for Plant Cell Biology University of California Riverside CA USA

Automated segmentation and tracking of cells in actively developing tissues can provide high-throughput and quantitative spatiotemporal measurements of a range of cell behaviors; cell expansion and cell-division kinetics leading to a better understanding of the underlying dynamics of morphogenesis. Here, we have studied the problem of constructing cell lineages in time-lapse volumetric image stacks obtained using Confocal Laser Scanning Microscopy （CLSM）. The novel contribution of the work lies in its ability to segment and track cells in densely packed tissue, the shoot apical meristem （SAM）, through the use of a close-loop, adaptive segmentation, and tracking approach. The tracking output acts as an indicator of the quality of segmentation and, in turn, the segmentation can be improved to obtain better tracking results. We construct an optimization function that minimizes the segmentation error, which is, in turn, estimated from the tracking results. This adaptive approach significantly improves both tracking and segmentation when compared to an open loop framework in which segmentation and tracking modules operate separately.

关键词： Shoot apical meristem stem cells cell tracking cell segmentation integrated segmentation and tracking

A Review on Thermophysical Properties and Nusselt Number Behavior of Al2O3 Nanofluids in Heat Exchangers

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Journal of Thermal Science 2021年第2期30卷 418-431页

作者： ISSA roy Jean College of Engineering West Texas A&M UniversityCanyonTexas 79016USA

During the last several years,the increase in cooling power requirements for heat exchangers have led to an escalation in heat transfer studies being performed on the use of nanofluids as heat transfer ***,limited effort has been attempted to relate and interpret these findings or the anomalies associated with *** paper compiles test data from several studies conducted on different types of heat *** this review,a concentrated effort is spent to clarify the ambiguities regarding the effect of nanoparticle size on the nanofluid thermal conductivity and Nusselt *** show that the nanofluid thermal conductivity is not influenced by the nanoparticle size,but by the clustering of the particles *** less compact the structure of the nanoparticle clustering is,the greater the enhancement in the nanofluid thermal conductivity *** were also compiled to interpret the relation between the nanofluid flow pattern,nanoparticles volume fraction in the base fluid,and the convective heat *** results from the majority of the heat exchanger studies show an increase in the heat transfer coefficient with the increase in nanoparticle volume ***,studies conducted on plate heat exchanges display some *** the majority of the heat exchanger studies with the exception of few,the decrease in the nanoparticle size is shown to result in an enhancement of the bulk fluid Nusselt *** test data also reveal that the effectiveness of the alumina nanoparticles is dependent on the flow *** increase in the nanoparticles concentration is shown to result in an increase in the nanofluid heat transfer enhancement as the fluid is transitioning from laminar to turbulent *** general,the smaller the nanoparticle size is,the greater the enhancement in the fluid Nusselt number is.

关键词： heat exchanger Nusselt number alumina nanofluid

An Estimation of the geometrical Structure of Polar Cap and Emission Property of Radio Pulsar:A Treatment from an Analytical Approach

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Research in Astronomy and Astrophysics 2023年第4期23卷 44-55页

作者： Tridib roy Indian Institute of Astrophysics Sarjapur Main RoadKoramangala 2nd BlockBangalore 560034India SN Bose National Cenre for Basic Science SaltlakeSector 3JD BlockKolkata 700106India

Pulsars are believed to be one of the most interesting objects in the *** emission mechanism of pulsars is still a conundrum to physicists,as there is no completely acceptable theory that can establish a consensus between theory and *** possess a g.g.ntic magnetic field,to the order of 10^(12)gauss,and generate a very powerful radio beam from the magnetic ***,the powerful radio beam is generated by some complicated coherent plasma processes and acceleration in the pulsar *** location of the origin of the radio waves has been predicted to come out exclusively from the polar cap zone,whose boundary is defined by the footprint of the last open field ***,in this paper,we mainly try to generate the shape of the polar cap structure from an analytical solution and discuss how it gets distorted for different geometrical parameters due to the presence of perturbation such as polar cap current ***,apart from that,we try to emphasize understanding the variation of radio emission height and polarization angle with respect to different geometryrelated parameters as well as with frequency.

关键词： (stars:)pulsars general-stars neutron-radiation mechanisms non-thermal

Promise and pitfalls of modeling.g.assland soil moisture in a free-air CO_(2) enrichment experiment(BioCON)using the SHAW model

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Pedosphere 2021年第5期31卷 783-795页

作者： Raquel H.FLINKER M.Bayani CARDENAS Todd g.CALDWELL gerald N.FLERCHINgER roy RICH Peter B.REICH Department of geological Sciences The University of Texas at AustinAustin 78712(USA) Bureau of Economic geology The University of Texas at AustinAustin 78713(USA) Agricultural Research Service United States Department of AgricultureBoise 83712(USA) Smithsonian Environmental Research Center Edgewater 20137(USA) Department of Forest Resources University of MinnesotaSt.Paul 55108(USA) Hawkesbury Institute for the Environment Western Sydney UniversitySydney 2753(Australia)

Free-air carbon dioxide(CO_(2))enrichment(FACE)experiments provide an opportunity to test models of heat and water flow under novel,controlled situations and eventually allow use of these models for hypothesis *** study assesses whether the United States Department of Agriculture SHAW(Simultaneous Heat and Water)numerical model of vertical one-dimensional soil water flow across the soil-plant-atmosphere continuum is able to adequately represent and explain the effects of increasing atmospheric CO_(2) on soil moisture dynamics in temperate *** in a FACE experiment,the Bio CON(Biodiversity,CO_(2),and Nitrogen)experiment,in Minnesota,USA,were compared with results of vertical soil moisture *** scenarios represented by different plots were assessed:bare,vegetated with ambient CO_(2),and similarly vegetated with high CO_(2).From the simulations,the bare plot soil was generally the wettest,followed by a drier high-CO_(2) vegetated plot,and the ambient CO_(2) plot was the *** SHAW simulations adequately reproduced the expected behavior and showed that vegetation and atmospheric CO_(2) concentration significantly affected soil moisture *** differences in modeled soil moisture amongst the plots were largely due to transpiration,which was low with high CO_(2).However,the modeled soil moisture only modestly reproduced the ***,while SHAW is able to replicate and help broadly explain soil moisture dynamics in a FACE experiment,its application for point-and time-specific simulations of soil moisture needs further *** typical design of a FACE experiment makes the experimental observations challenging to model with a one-dimensional distributed *** addition,FACE instrumentation and monitoring will need improvement in order to be a useful platform for robust model *** after this can we recommend that models such as SHAW are adequate for process interpretation of datasets from FACE exp

关键词： carbon dioxide FACE experiment soil water flow vadose zone vegetation

A synchronous duty-cycled reservation based MAC protocol for underwater wireless sensor networks

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Digital Communications and Networks 2021年第3期7卷 385-398页

作者： Alak roy Nityananda Sarma Department of Information Technology Tripura UniversityWest TripuraIndia Department of Computer Science and Engineering Tezpur UniversityAssamIndia

To design an energy-efficient Medium Access Control(MAC)protocol for the Underwater Wireless Sensor Networks(UWSNs)is an urgent research issue since depleted batteries cannot be recharged or replaced in the underwater ***,the underwater acoustic channels are affected by hindrances such as long propagation delay and limited bandwidth,which appear in the design of the MAC protocol for the *** available MAC protocols for the terrestrial wireless sensor networks exhibit low performance in energy efficiency,throughput and reliability in the UWSNs,and cannot be used in the UWSNs directly because of their unique *** paper proposes a synchronous duty-cycled reservation-based MAC protocol named Ordered Contention MAC(OCMAC)*** basic mechanism of this protocol is to schedule data transmission by transmitters through the scheduling of Ready To Send(RTS)*** protocol eliminates the possible collision during data transmission and improves communication *** paper analyzes the performance in energy efficiency,throughput and reliability of the protocol by modeling the queuing behavior of OCMAC with a Markov Chain ***,the analytical model is validated through a simulation *** analysis results demonstrated that while providing.g.od throughput and reliability,OCMAC can achieve energy saving.

关键词： Underwater wireless sensor networks MAC protocol Energy efficiency Throughput Reliability Acoustic communication OCMAC

Structural,optical,electrical,and dielectric relaxation properties of rare earth containing sodium bismuth titanate Na_(0.5)Bi_(0.5)TiO_(3) perovskite:Effect of ionic radius

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Journal of Rare Earths 2024年第2期42卷 383-391,I0006页

作者： Rajdip roy Abhigyan Dutta Department of Physics The University of BurdwanBurdwan713104India

The main focus of this work is to study the effect of the ionic radius of different rare earth dopant cations RE^(3+)(RE=La,Sm,Dy,and Ho) on structural and various physical properties of sodium bismuth titanate(Na_(0.5)B_(0.5)TiO_(3),NBT) based perovskite *** X-ray diffraction data indicate the successful formation of the rhombohedral phase(space group R3c) of NBT nano perovskite incorporated with various rare earth ions in *** lattice parameters were found to increase linearly with the ionic radius of the dopant *** ionic radii and atomic mass of rare earth dopants appear to be essential factors in the grain growth of the prepared *** grain growth results in better crystallinity of the sample by reducing the microstrain with the increase of dopant ionic *** emission scanning electron microscopy and energy-dispersive X-ray spectra confirm the prepared compositions' phase purity and *** UV-Vis spectra reveal that La-doped NBT composition exhibits the lowest optical band gap,which unfolds the application of NBT-based perovskite as photoactive *** ac conductivity and complex impedance spectra unveil that the composition with the largest ionic radius,i.e.,La-doped NBT compound,exhibits the highest dc and bulk conductivity with the lowest activation *** frequency-dependent dielectric data follows Havriliak-Negami(HN) formalism and non-Debye type relaxation *** also indicate that La-doped NBT composition exhibits the highest dielectric strength ***,this study first elaborates that the increasing ionic radius of the rare earth dopant cation in the Bi-site of NBT perovskite improves its microstructural,optical,and electrical properties.

关键词： Rare earth doped NBT Microstructural analysis Optical band gap AC Conductivity Dielectric relaxation Rare earths

Time evolution of the matter content of the expanding universe in the framework of Brans-Dicke gravity

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Research in Astronomy and Astrophysics 2019年第4期19卷 137-150页

作者： Sudipto roy Department of Physics St.Xavier's College30 Mother Teresa Sarani (Park Street)

A cosmological model has been constructed in the framework of Brans-Dicke(BD) gravity,based on an inter-conversion between matter and dark energy, for a spatially flat universe in the era of pressureless dust. To account for the non-conservation of the matter content, a function of time f(t) has been arbitrarily put into the expression for the density of matter(ρa^3= f(t)ρ_0 a_0~3). By definition, f(t) is proportional to the matter content of the universe. Using suitable ansatzes for the scale factor and scalar field, the functional form of f(t) has been determined from the BD field equations. The scale factor has been so chosen that it would cause a signature flip in the deceleration parameter with time. The function f(t) decreases monotonically with time, indicating a transformation of matter into dark energy. The time dependence of the proportions of matter and dark energy in the universe has been determined. The effect of non-conservation of the matter content upon various cosmological parameters has been explored in the present study. Two models of matter-energy interaction have been proposed and f(t) has been expressed as a function of their interaction term. The dark energy equation-of-state(EoS) parameter has been expressed and analyzed in terms of f(t).

关键词： cosmology:cosmological parameters dark energy Brans-Dicke theory