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International Journal of sediment Research 2012年第3期27卷 378-387页

作者： H.MAITY b.s.mazumder Fluvial Mechanics Laboratory Physics and Applied Mathematics UnitIndian Statistical Institute

This paper investigates the phenomena of turbulent bursting events,and to make a comparative study among the events in the scour geometry developed by short circular cylinders of fixed length with different diameters placed on the sand bed transverse to the *** distributions of turbulent kinetic energy(TKE),turbulent diffusion in both longitudinal and vertical directions at different locations of scour marks,and the contributions of burst-sweep cycles to the Reynolds shear stress are presented.

关键词： scour marks TKE Turbulent diffusion Reynolds stress bursting events

Turbulence,suspension and downstream fining over a sand-gravel mixture bed

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International Journal of sediment Research 2013年第2期28卷 194-209页

作者： K.GHOsHAL Rahul mazumder C.CHAKRAbORTY b.s.mazumder Department of Mathematics Indian Institute of TechnologyKharagpur 721302India Assist.Prof. MIT CambridgeUSA Post-Doctoral Assoc. Fluvial Mechanics Laboratory Physics and Earth Science DivisionIndian Statistical InstituteKolkata 700108India Prof.

Flume experiments were carried out to study the turbulence and its impact on suspension and segregation of grainsizes under unidirectional flow conditions over the sand-gravel mixture *** components of fluid velocity with fluctuations were measured vertically using 3-D Micro-acoustic Doppler velocimeter(ADV).The theoretical models for velocity and sediment suspension have been developed based on the concept of mixing length that includes the damping effect of turbulence due to sediment suspension in the flow over the sand-gravel mixture *** analysis of segregation of grain-sizes along downstream of the bed has been performed using the principle of unsupervised learning or clustering *** data analysis suggests that there is a progressive downstream fining of sediment sizes with selective depositions of gravels,sand-gravels and sand materials along the stream,which may be segmented into three regions such as,the upstream,the transitional and the downstream *** contribution is relevant to understand the direction of ancient rivers,the bed material character in the river form,sorting process and its role in controlling the sediment flux through landscape.

关键词： sand-gravel mixture Flow velocity ADV suspension concentration size-sorting Clustering

Hydrodynamic dispersion of reactive solute in a Hagen–Poiseuille flow of a layered liquid

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Chinese Journal of Chemical Engineering 2017年第7期25卷 862-873页

作者： sudip Debnath Apu Kumar saha b.s.mazumder Ashis Kumar Roy Department of Mathematics National Institute of TechnologyAgartala 799046India Fluvial Mechanics Laboratory Physics and Applied Mathematics UnitIndian Statistical InstituteKolkata 700108India Fluid Mechanics and Hydraulic Laboratory(FMHL) Department of Aernspace Engineering and Applied MechanicsIndian Institute of Engineering Science and Technology(IIEST)ShibpurHowrah 711103India

An analysis of the solute dispersion in the liquid flowing through a pipe by means of Aris–barton's ‘method of moments', under the joint effect of some finite yield stress and irreversible absorption into the wall is presented in this paper. The liquid is considered as a three-layer liquid where the center region is Casson liquid surrounded by Newtonian liquid layer. A significant change from previous modelling exercises in the study of hydrodynamic dispersion, different molecular diffusivity has been considered for the different region yet to be constant. For all time period, finite difference implicit scheme has been adopted to solve the integral moment equation arising from the unsteady convective diffusion equation. The purpose of the study is to find the dependency of solute transport coefficients on absorption parameter, yield stress, viscosity ratio, peripheral layer variation and in addition with various diffusivity coefficients in different liquid layers. This kind of study may be useful for understanding the dispersion process in the blood flow analysis.

关键词： Casson liquid Yield stress Axial-dispersion coefficient Irreversible reaction Diffusivity

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Turbulent flow field over fluvial obstacle marks generated in a laboratory flume

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International Journal of sediment Research 2011年第1期26卷 62-77页

作者： b.s.mazumder H.MAITY T.CHADDA Fluvial Mechanics Laboratory HeadPhysics and Applied Mathematics UnitIndian Statistical InstituteCalcutta-700 108India Fluvial Mechanics Laboratory Physics and Applied Mathematics UnitIndian Statistical Institute Calcutta-700 108INDIA Institute for Fluid Dynamics Mechanical and Process Engineering Department.ETH Zurich(Swiss Federal Institute of Technology)

The study is aimed at investigating the mean flow and turbulence characteristics in scour geometry developed near a circular cylinder of length 10cm placed over the sand bed transverse to the *** obstacle placed on a sand bed,on the way of a unidirectional flow,develops a crescent-shaped scour mark on the *** scour is caused by generation of vortex developed on the upstream side of the *** grains eroded by this vortex,are deposited on the downstream side of the obstacle as *** turbulent flow field within the scour mark was measured in a laboratory flume using an Acoustic Doppler Velocimeter(ADV).The scour marks named as current crescents preserved in geological record are traditionally used as indicators of palaeocurrent *** distribution of mean velocity components,turbulent intensities and Reynolds stresses at different positions of the mark are *** experimental evidence also shows that the geometric characteristics of the scour mark(width) depend primarily on the cylinder aspect ratio,cylinder Reynolds number and sediment Froude number.

关键词： Turbulence Open channel flow Erosion scour mark sediment transport

Multi-scale analysis for transport of fine settling particles through an ice-covered channel in a laminar flow condition

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International Journal of sediment Research 2022年第6期37卷 794-808页

作者： subham Dhar Nanda Poddar b.s.mazumder Kajal Kumar Mondal Department of Mathematics Cooch Behar Panchanan Barma University Physics and Applied Mathematics Unit Indian Statistical Institute Department of Civil Engineering Indian Institute of Technology Bombay

The current research deals with the dispersion of fine settling particles in a fluid flowing through an icecovered channel under the laminar flow condition. An analytical solution of the two-dimensional convection-diffusion equation, based on the multi-scale homogenization technique, is obtained. To validate the current study, analytical results for the dispersion coefficient are compared with the available earlier research work. Moreover, the proposed analytical solutions for mean concentration distributions of the tracers are compared with the numerical results obtained from the finite difference technique. From the industrial and environmental points of view, the vertical concentration distribution provides a very significant information. The downstream evolution of the concentration distribution also is shown for typical time periods at different values of the settling velocity. The approach to the vertical uniformity shows that it is too slow a process in comparison to that of longitudinal normality. It was found that settling velocities of particles disturb the vertical uniformity and the centroid of the solute cloud rises due to the increase in settling velocity. Results illustrate that in the downstream direction, the vertical concentration distribution increases near the bed surface and it decreases in the proximity of the ice-covered surface of the channel with the increase of settling velocity, but the mean concentration of the solute increases. The current study may play an important role to understand the mechanism of the sedimentation process in a closed channel system.

关键词： sediment transport Dispersion Ice-covered channel Vertical uniformity Multi-scale analysis

VELOCITY AND sUsPENsION CONCENTRATION IN sEDIMENT-MIXED FLUID

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International Journal of sediment Research 2002年第3期17卷 220-232页

作者： b.s.mazumder,K.GHOsHAL Professor Physics and Applied Mathematics Unit Indian statistical Institute Calcutta-700 108 India. Project Fellow Flume Laboratory Physics and Applied Mathematics Unit Indian statistical Institute Calcutta-700 108 India.

The present paper is focussed on the effects of viscous and turbulent shear stresses on both vertical velocity and concentration distributions in large suspension of sands. When the flow carries large amount of sediments in suspension, the properties of fluid mixture are changed in terms of modified viscosity, density and fall velocity, and hence the flow characteristics. Theoretical models have been developed for both velocity and concentration profiles, taking into account the viscous and turbulent shear stresses, which are the function of volumetric concentration. Comparison of theoretical models with experimental data reveals that (i) the modified velocity and concentration profiles agree well with the observed data for high suspension, (ii) the higher the sediment suspension, the smaller the von-Karman constant, and (iii) sediment diffusion coefficient is less than momentum diffusion coefficient for fine sands in suspension.

关键词： sediment suspension Viscosity Turbulent shear stress Hindered settling Velocity and concentration profiles

Quantized autoencoder(QAE)intrusion detection system for anomaly detection in resource-constrained loT devices using RT-loT2022 dataset

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Cybersecurity 2024年第2期7卷 13-27页

作者： b s sharmila Rohini Nagapadma Depatment of Electronics and Communication Engineering The National Institute of EngineeringMysoreKarnataka 570008India

In recent years,many researchers focused on unsupervised learning for network anomaly detection in edge devices to identify *** deployment of the unsupervised autoencoder model is computationally expensive in resource-constrained edge *** study proposes quantized autoencoder(QAE)model for intrusion detection systems to detect *** is an optimization model derived from autoencoders that incorporate pruning,clustering,and integer quantization *** autoencoder uint8(QAE-u8)and quantized autoencoder float16(QAE-f16)are two variants of QAE built to deploy computationally expensive Al models into Edge ***,we have generated a Real-Time Internet of Things 2022 dataset for normal and attack *** autoencoder model operates on normal traffic during the training *** same model is then used to reconstruct anomaly traffic under the assumption that the reconstruction error(RE)of the anomaly will be high,which helps to identify the ***,we study the performance of the autoencoders,QAE-u8,and QAE-f16 using accuracy,precision,recall,and F1 score through an extensive experimental *** showed that QAE-u8 outperforms all other models with a reduction of 70.01%in average memory utilization,92.23%in memory size compression,and 27.94%in peak CPU ***,the proposed QAE-u8 model is more suitable for deployment on resource-constrained IoT edge devices.

关键词： IoT constrained system

Fuzzy Reliability and Availability of system under a Calendar-based Inspection Involving Multiple Failures and Its Application to Wind Turbine system

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Journal of systems science and systems Engineering 2024年第2期33卷 187-206页

作者： Mintu Kumar Himani Pant s.b.singh Department of Mathematics statistics and Computer science G.B.Pant University of AgricultureTechnologyPantnagarUttarakhandIndia

Uncertainty is an important factor that needs to be considered while analyzing the performance of any engineering *** order to quantify uncertainty,fuzzy set theory is frequently used by most of researchers,including energy system *** to the classical reliability theory,component lifetimes have crisp parameters,but due to uncertainty and inaccuracy in data,it is sometimes very difficult to determine the exact values of these parameters in real-world *** overcome this difficulty in the current research,failure and repair rates were taken as triangular fuzzy numbers to determine the fuzzy availability of a system undergoing calendar-based periodic inspection subject to multiple failure modes(FMs).It was assumed that each component in the system had an exponential failure rate and repair rate with fuzzy *** FMs were explicitly taken into account when a functional state of the system was *** FM had a random failure *** the occurrence of any failure,a random time was selected for the relevant corrective repair *** proposed research was studied for one of the major sources of green energy,namely a wind turbine system wherein all the derived propositions have been implemented on it.

关键词： Fuzzy reliability fuzzy availability wind turbine system multiple failure modes triangular fuzzy number

study of hybrid nanofluid flow in a stationary cone-disk system with temperature-dependent fluid properties

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Applied Mathematics and Mechanics(English Edition) 2024年第4期45卷 677-694页

作者： A.s.JOHN b.MAHANTHEsH G.LORENZINI Center for Mathematical Needs Department of MathematicsCHRIST(Deemed to be University)Karnataka 560029India school of Mathematical and statistical sciences The University of Texas Rio Grande ValleyTexas 78539U.S.A. Department of Engineering and Architecture University of ParmaParma 43124Italy

Cone-disk systems find frequent use such as conical diffusers,medical devices,various rheometric,and viscosimetry *** this study,we investigate the three-dimensional flow of a water-based Ag-Mg O hybrid nanofluid in a static cone-disk system while considering temperature-dependent fluid *** the variable fluid properties affect the dynamics and heat transfer features is studied by Reynolds's linearized model for variable viscosity and Chiam's model for variable thermal *** single-phase nanofluid model is utilized to describe convective heat transfer in hybrid nanofluids,incorporating the experimental *** model is developed as a coupled system of convective-diffusion equations,encompassing the conservation of momentum and the conservation of thermal energy,in conjunction with an incompressibility condition.A self-similar model is developed by the Lie-group scaling transformations,and the subsequent self-similar equations are then solved *** influence of variable fluid parameters on both swirling and non-swirling flow cases is ***,the Nusselt number for the disk surface is *** is found that an increase in the temperature-dependent viscosity parameter enhances heat transfer characteristics in the static cone-disk system,while the thermal conductivity parameter has the opposite effect.

关键词： hybrid nanofluid cone-disk system laminar flow variable fluid property Nusselt number

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Astrophysical s-factor and reaction rate for 15N(p,γ)16O within the modified potential cluster model

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Chinese Physics C 2024年第4期48卷 130-145页

作者： s.b.Dubovichenko A.s.Tkachenko R.Ya.Kezerashvili N.A.burkova b.M.Yeleusheva Fesenkov Astrophysical Institute 050020 AlmatyKazakhstan New York City College of Technology City University of New YorkBrooklyn11201 New YorkUSA Graduate school and University Center City University of New York10016 New YorkUSA al-Farabi Kazakh National University 050040 AlmatyKazakhstan

We study radiative p^(15)N capture on the ground state of ^(16)O at stellar energies within the framework of a modified potential cluster model(MPCM)with forbidden states,including low-lying *** investigation of the ^(15)N(p,γ0)^(16)O reaction includes the consideration of ^(3)s_(1) resonances due to E1 transitions and the contribution of the ^(3)P_(1) scattering wave in the p+^(15)N channel due to the ^(3)P_(1)→^(3)P_(0)M1 *** calculated the astrophysical low-energy s-factor,and the extrapolated s(0)turned out to be within 34.7−40.4 keV·*** important role of the asymptotic constant(AC)for the ^(15)N(p,γ0)16O process with interfering ^(3)s_(1)(312)and ^(3)s_(1)(962)resonances is elucidated.A comparison of our calculation for the s-factor with existing experimental and theoretical data is addressed,and a reasonable agreement is *** reaction rate is calculated and compared with the existing *** has negligible dependence on the variation of AC but shows a strong impact of the interference of ^(3)s_(1)(312)and ^(3)s_(1)(962)resonances in reference to the CNO Gamow windows,especially at low *** estimate the contribution of cascade transitions to the reaction rate based on the exclusive experimental data from ***.C.85,065810(2012).The reaction rate enhancement due to the cascade transitions is observed from T_(9)>0.3 and reaches the maximum factor~1.3 at T_(9)=*** present the Gamow energy window and a comparison of rates for radiative proton capture reactions ^(12)N(p,γ)^(13)O,^(13)N(p,γ)^(14)O,^(14)N(p,γ)^(15)O,and ^(15)N(p,γ)^(16)O obtained in the framework of the MPCM and provide the temperature windows,prevalence,and significance of each process.

关键词： low and astrophysical energies p^(15)N system thermonuclear reaction rate potential cluster model CNO-cycle

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