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Evaluation of vertical impact factor coefficients for continuous and integral railway bridges under high-speed moving loads

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Earthquake Engineering and Engineering Vibration 2021年第2期20卷 495-504页

作者： Anand M.Gharad ranjan S.Sonparote Civil Engineering Department Shri Ramdeobaba College of Engineering and ManagementNagpur 440013India Department of Applied Mechanics Visvesvaraya National Institute of TechnologyNagpur 440010India

In the railway bridge analysis and design method,dynamic train loads are regarded as static loads enhanced by an impact factor(IF).The IF coefficients for various railway bridges have been reported as a function of span length or frequency of the bridges in Eurocode(2003).However,these IF coefficient values neglect the effects of very high speeds(>200 km/h)and soil-structure interaction(SSI).In this work,a comprehensive study to assess the impact factor coefficients of mid-span vertical displacements for continuous and integral railway bridges subjected to high-speed moving loads is *** different configurations,each for the three-dimensional(3D)continuous and integral bridge,are ***,single-track(1-T)and two-track(2-T)“real train”loading cases for both these bridge types are ***,finite element analysis of the full-scale 3D bridge models,to identify their IF values,considering the effects of SSI for three different soil conditions,is *** IF values obtained from the study for both bridge types are comparable and are greater than the values recommended by Eurocode(2003).The results reveal that with a loss of soil stiffness,the IF value reduces;thus,it confirms the importance of SSI analysis.

关键词： impact factor dynamic soil-structure interaction high-speed moving loads finite element analysis continuous bridge integral bridge

Appropriate method of core selection and crosstalk optimization in single-mode homogeneous multicore fiber

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Optoelectronics Letters 2020年第2期16卷 126-130页

作者： DABLU Kumar RAKESH ranjan Optical Fiber Communication and Photonics Lab Department of Electronics and Communication EngineeringNational Institute of Technology(NIT)PatnaPatna 800005India

The approach for homogeneous core structure design and selection based on low crosstalk, low dispersion, and acceptable mode effective area have been explored. The forward and backward crosstalk behaviors with respect to wavelength, fiber bending radius, and twisting rate in 12-core, and 21-core single-mode trench-assisted homogenous multicore fiber have been analyzed. The new expression for forward crosstalk under bending and twisting conditions has been derived using the conventional method. For the analysis and optimization of crosstalk, three different core structures are considered, it helps to draw the attention to select the appropriate core structure model for multicore fiber, which follows the standards used in telecom services.

关键词： crosstalk fiber trench

Pattern of spatial variability in granulometric and mineralogical characteristics across an ecologically sensitive sub-tropical wetland(Bihar, India)

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International Journal of Sediment Research 2023年第4期38卷 516-529页

作者： Alvia Aslam Rajesh Kumar ranjan Avinash Dass Department of Environmental Science Central University of South Bihar

Floodplain wetlands are dynamic systems undergoing frequent hydro-sedimentological changes. Tropical/subtropical wetlands have even more pronounced climatic and biological influences on the sediment dynamics. In the current study, a protected subtropical wetland in Bihar(India) has been assessed for its sedimentary and mineralogical status. Sediment characteristics and associated granulometric parameters are discussed to highlight the wetland’s hydrogeomorphic character, energy dimension, and the depositional processes taking place. Statistical grain size parameters like graphic mean, graphic skewness,graphic kurtosis, and their interrelations studies have helped in understanding the sources of deposited materials. Multivariate statistics have identified, sand fractions, measures of central tendencies(mean,median, and mode), percent organic matter(%OM) and percent carbonates(%carbonates) as primary factors explaining the maximum variance in the data. The non-parametric Kruskal-Wallis test has identified %sand, %clay, electrical conductivity(EC), and %carbonates as the major factors responsible for significant spatial variability. The grain texture analysis shows that the majority of samples fall in the brackets of clayey silt; silty sand; and sand, silt, and clay. Common mineral components associated with these are quartz, feldspar, clay minerals, etc. The range for the mean grain size lies between 3Φ to 9Φ(Φ is diameter of the sediments) where most of the grain size distributions are symmetrically to fine symmetrically skewed, indicating intermediate energy to adjust to environmental conditions. The granulometric and physicochemical characteristics of the sediment samples also indicate the directional distribution pattern of sediment along the hydrological pathway. Future studies concentrating on the fluvial discharges of water and sediment will be highly insightful in reconstructing the past net sediment accumulation processes in the Baraila Wetland.

关键词： Grain size analysis Hydrodynamic energy Mineralogy Allogenic source Terrigenous input Wetland

Nonlinear dynamic analysis of dragonfly-inspired piezoelectric unimorph actuated flapping and twisting wing

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International Journal of Smart and Nano Materials 2012年第2期3卷 103-122页

作者： Sujoy Mukherjee ranjan Ganguli Department of Aerospace Engineering Indian Institute of ScienceBangalore-560012KarnatakaIndia

The nonlinear equations for coupled elastic flapping-twisting motion of a dragonfly-inspired smart flapping wing are used for a flapping wing actuated from the root by a PZT unimorph in the piezofan *** by the piezoelectric harmonic force generates only the flap bending motion,which,in turn,induces the elastic twist motion due to interaction between flexural and torsional vibration *** unsteady aerodynamic model is used to obtain the aerodynamic *** simulations are performed using a wing whose size is the same as the dragonfly Sympetrum frequens *** is found that the value of average lift reaches its maximum when the smart flapping wing is excited at a frequency closer to the natural frequency in ***,consideration of the elastic twisting of the flapping wing leads to an increase in the lift *** is also found that the flapping wing generates sufficient lift to support its own weight and carry a small ***,the piezoelectrically actuated smart flapping wing based on the geometry of a Sympetrum frequens wing and undergoing flapping-twisting motions can be considered as a potential candidate for use in micro air vehicle applications.

关键词： piezofan nonlinear vibration coupled flapping-twisting dragonfly smart material micro air vehicle

Modelling of Wideband Concentric Ring Frequency Selective Surface for 5G Devices

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Computers, Materials & Continua 2023年第1期74卷 341-361页

作者： Ankush Kapoor Pradeep Kumar ranjan Mishra Department of Electronics and Communication Engineering Jawaharlal Nehru Government Engineering CollegeSundernagar175018India Discipline of Electrical Electronic and Computer EngineeringUniversity of KwaZulu-NatalDurban4041South Africa Department of Electrical and Electronics Engineering University of Petroleum and Energy StudiesDehradun248007India

Frequency selective surfaces(FSSs)play an important role in wireless systems as these can be used as filters,in isolating the unwanted radiation,in microstrip patch antennas for improving the performance of these antennas and in other 5G *** analysis and design of the double concentric ring frequency selective surface(DCRFSS)is presented in this *** the sub-6 GHz 5G FR1 spectrum,a computational synthesis technique for creating DCRFSS based spatial filters is *** analytical tools presented in this study can be used to gain a better understanding of filtering processes and for constructing the spatial *** of the loop sizes,angles of incidence,and polarization of the concentric rings are the factors which influence the transmission coefficient as per the thorough investigation performed in this paper.A novel synthesis approach based on mathematical equations that may be used to determine the physical parameters ofDCRFSSbased spatial filters is *** proposed synthesis technique is validated by comparing results from high frequency structure simulator(HFSS),Ansys electronic desktop circuit editor,and an experimental ***,the findings acquired from a unit cell are expanded to a 2×2 array,which shows identical performance and therefore proves its stability.

关键词： Spatial filters double concentric ring frequency selective surface(DCRFSS) angle of incidence finite element method(FEM) polarization angles

CFD modeling and laboratory studies of dust cleaning efficacy of an efficient four stage non-clogging impingement filter for flooded-bed dust scrubbers

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International Journal of Coal Science & Technology 2022年第2期9卷 211-219页

作者： Ashish ranjan Kumar Neeraj Gupta Steven Schafrik Department of Mining Engineering University of KentuckyLexingtonKYUSA Department of Mining and Nuclear Engineering Missouri University of Science and Technology1400 N.Bishop AveRollaMO 65401USA

Fibrous-type flters are used to capture dust particles in mining and other occupations where personnel are exposed for prolonged *** cleansing devices including fooded-bed dust scrubbers use these mesh-type multi-layered *** flters trap dust particles efciently on their surface and inside their ***,their continued operation leads to dust build-up and *** results in increased resistance of the flter and lowered airfow rate through the *** could potentially enhance the exposure of the miners.A non-clogging self-cleaning impingement screen type dust flter was designed by the authors for use in mining and industrial dust cleansing *** flter guides dirt-laden air through rapidly turning paths which forces it to shed heavier *** particles impact one of the impermeable solid metallic flter surfaces and are removed from the airstream.A full cone water spray installed upstream prevents any surface buildup of *** paper summaried the computer models generated to show the flter operations and laboratory experiments including optical particle counting to establish the cleaning efciency.

关键词： Dust flter Computational fuid dynamics modeling Iso-kinetic sampling Optical particle counting Flooded-bed dust scrubber

Metamaterial inspired terahertz devices: from ultra-sensitive sensing to near field manipulation

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Chinese Optics Letters 2013年第1期11卷 36-40页

作者：王锦王爽 ranjan Singh 张伟力 School of Electronic Engineering Tianjin University of Technology and Education School of Electrical and Computer Engineering Oklahoma State University AOT-HPE Los Alamos National Laboratory

We present a review of terahertz plasmonic metamaterial devices that have functionalities and applications ranging from sensing, enhanced electromagnetic fields, and near field manipulation. Metamaterials allow the properties of light propagation to be manipulated at will by using a combination of appropriately designed geometry and suitable materials at the unit cell level. In this review, we first discuss the sensing aspect of a planar plasmonic metamaterial and how to overcome its limitations. Conventional symmetric metamaterials are limited by their low Q factor, thus we probed the symmetry broken plasmonic metama- terial structures in which the interference between a broad continuum mode and a narrow localized mode leads to the excitation of the sharp Fano resonances. We also discuss the near field mediated excitation of dark plasmonic modes in metamaterials that is caused by a strong coupling from the bright mode res- onator. The near field coupling between the dark and bright mode resonances leads to classical analogue of electromagnetically induced transparency in plasmonic systems. Finally, we discuss active switching in terahertz metamateriMs based on high temperature superconductors that holds the promise of reducing the resistive losses in these systems, though it fails to suppress the radiation loss in plasmonic metamaterial at terahertz frequencies.

关键词： Dipole antennas Electromagnetic fields Geometry High temperature superconductors Plasmons Resonance

A REMARK ON LARGE TIME ASYMTOTICS FOR SOLUTIONS OF A NONHOMOGENEOUS VISCOUS BURGERS EQUATION

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Acta Mathematica Scientia 2023年第3期43卷 1323-1332页

作者： Manas ranjan SAHOO Satyanarayana ENGU Smriti TIWARI School of Mathematical Sciences National Institute of Science Education and ResearchAn OCC of Homi Bhabha National InstituteBhubaneswarKhurdaOdishaP.O.Jatni752050India Department of Mathematics National Institute of TechnologyWarangalTelangana506004India

The existence, uniqueness and regularity of solutions to the Cauchy problem posed for a nonhomogeneous viscous Burger's equation were shown in Chung, Kim and Slemrod [1] by assuming suitable conditions on initial data. Moreover, they derived the asymptotic behaviour of solutions of the Cauchy problem by imposing additional conditions on initial data. In this article, we obtain the same asymptotic behaviour of solutions to the Cauchy problem without imposing additional condition on initial data.

关键词： modified Bessel functions integral equation large time asymptotics convolution of functions

Non-Newtonian Flow of Blood in a Catheterized Bifurcated Stenosed Artery

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Journal of Bionic Engineering 2018年第1期15卷 173-184页

作者： Jagadis Chandra Misrat Gopal Chandra Shit ranjan Pramanik Centre for Healtheare Science and Technology Indian Institute of Engineering Science and Technology Shibpur 711103 lndia Department of Mathematics Jadavpur University Kolkata 700032 India Department of Mathematics Indian Institute of Technology Kharagpur 721302 lndia

The paper is devoted to study the non-Newtonian behavior of blood flowing in an artery having a stenosis, in a situation when a catheter has been inserted into it. The blood rheology is described by Herschel-Bulkley fluid model. The flow configuration is con- structed by choosing suitable curvature at the lateral junction, where the flow separation is initiated. The effects of insertion of catheter and that of yield stress of blood on the velocity distribution, rate of flow and flow resistance of blood, distribution of shear stress at the arterial wall and the location of yield plane are investigated. The results provide some useful information for the prediction/treatment of some arterial diseases and circulatory disorders of the cardiovascular system, in a situation, when a stenosis is developed on the endothelium of the daughter artery / bifurcated artery. The study reveals that if the ratio between the radii of the catheter and the artery is increased, the shear stress at the arterial wall diminishes. However, when the bifurcation angle is increased, the wall shear stress is enhanced.

关键词： Herschel-Bulkley fluid model arterial bifurcation catheterized artery yield plane flow resistance