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A new protocol for concurrently allocating licensed spectrum to underlay cognitive users

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Digital Communications and Networks 2018年第3期4卷 200-208页

作者： Sabyasachi Chatterjee Prabir banerjee Mita Nasipuri Department of Electronics and Communication Engineering Heritage Institute of Technology Kolkata India Department of Computer Science Engineering Jadavpur university Kolkata India

Cognitive radio technology makes efficient use of the valuable radio frequency spectrum in a non-interfering manner to solve the problem of spectrum scarcity. This paper aims to design a scheme for the concurrent use of licensed frequencies by Underlay Cognitive Users （UCUs）. We develop a new receiver-initiated Medium Access Control （MAC） protocol to facilitate the selections of alternative reliable carrier frequencies. A circuit is designed to establish reliable carrier selections based on the Received Signal Strength Indicator （RSSI） at the receiving end. Based on both packet-level simulations and various performance parameters, a comparison is carried out among conventional techniques, including the Multiple Access with Collision Avoidance （MACA） and MACA by invitation（MACA-BI） techniques, and our scheme. The simulated results demonstrate that when conventional techniques are used, the system overhead time increases from 0.5 s on the first attempt to 16.5 s on the sixth attempt. In the proposed scheme under the same failure condition, overhead time varies from 0.5 s to 2 s. This improvement is due to the complete elimination of the exponential waiting time that occurs during failed transmissions. An average efficiency of 60% is achieved with our scheme while only 43% and 34% average efficiencies are achieved with the MACA and MACA-BI techniques, respectively. The throughput performance of our scheme on the fourth attempt is 7 Mbps, whereas for the MACA and MACA-BI protocols, it is 1.9 Mbps and 2.2 Mbps respectively.

关键词： Exponential back-off time Interference temperature limit Medium-access control protocol Received signal strength indicator Underlay cognitive user

Propagating disturbances along a coronal loop from simultaneous EUV imaging and spectroscopic observations

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Research in Astronomy and Astrophysics 2015年第7期15卷 1027-1035页

作者： Ajanta Datta S.Krishna Prasad Dipankar banerjee HKBK College of Engineering Indian Institute of Astrophysics Astrophysics Research Centre School of Mathematics and Physics Queen's University Belfast

Propagating disturbances（PDs） were studied along an active region loop using simultaneous imaging and spectroscopy. An image sequence recorded in the Fe Ⅸ/Fe X 171  channel, from TRACE and spectral data in the Si Ⅻ 520.6  line obtained from CDS/SOHO, are analyzed. A space-time map constructed from the TRACE image sequence shows the presence of PDs close to the loop foot point propagating with an apparent speed of 39 km s-1. The periodicity was found to be 5.4 *** corresponding spectroscopic data from CDS, at a location away from the foot point, show oscillations in all three line parameters roughly at the same period. At locations farther from the foot point, the line width oscillation seems to disappear while the Doppler velocity oscillation becomes prominent. We attribute this to the signature of propagating slow waves that get affected by flows/other events close to the foot point. Spectral line profiles do not show much asymmetry, however, it is difficult to infer anything due to the broadened Gaussian shape of the CDS line profiles.

关键词： Sun: corona -- oscillations -- UV radiation -- imaging spectroscopy

Intrusion Detection System Using Classification Algorithms with Feature Selection Mechanism over Real-Time Data Traffic

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China Communications 2024年第9期21卷 292-320页

作者： Gulab Sah Sweety Singh Subhasish banerjee Computer Science and Engineering National Institute of Technology Arunachal PradeshIndia

The key objective of intrusion detection systems(IDS)is to protect the particular host or network by investigating and predicting the network traffic as an attack or *** IDS uses many methods of machine learning(ML)to learn from pastexperience attack *** based and identify the new *** though these methods are effective,but they have to suffer from large computational costs due to considering all the traffic features,***,emerging technologies like the Internet of Things(Io T),big data,*** getting advanced day by day;as a result,network traffics are also increasing ***,the issue of computational cost needs to be addressed ***,in this research,firstly,the ML methods have been used with the feature selection technique(FST)to reduce the number of features by picking out only the important ones from NSL-KDD,CICIDS2017,and CIC-DDo S2019datasets later that helped to build IDSs with lower cost but with the higher performance which would be appropriate for vast scale *** experimental result demonstrated that the proposed model *** tree(DT)with Recursive feature elimination(RFE)performs better than other classifiers with RFE in terms of accuracy,specificity,precision,sensitivity,F1-score,and G-means on the investigated datasets.

关键词： CICIDS2017 dataset classifiers IDS ML NSL KDD dataset RFE

Relativistic compact stars with charged anisotropic matter

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Chinese Physics C 2018年第5期42卷 104-116页

作者： S.K.Maurya Ayan banerjee Phongpichit Channuie Department of Mathematical & Physical Sciences College of Arts & Science University of Nizwa Department of Mathematics Faculty of Applied Sciences Durban University of Technology School of Science Walailak University

In this article, we perform a detailed theoretical analysis of new exact solutions with anisotropic fluid distribution of matter for compact objects subject to hydrostatic equilibrium. We present a family solution to the Einstein-Maxwell equations describing a spherically symmetric, static distribution of a fluid with pressure *** implement an embedding class one condition to obtain a relation between the metric functions. We generalize the properties of a spherical star with hydrostatic equilibrium using the generalised Tolman-Oppenheimer-Volkoff(TOV)equation. We match the interior solution to an exterior Reissner-Nordstr?m one, and study the energy conditions,speed of sound, and mass-radius relation of the star. We also show that the obtained solutions are compatible with observational data for the compact object Her X-1. Regarding our results, the physical behaviour of the present model may serve for the modeling of ultra compact objects.

关键词： Class I spacetime exact solutions compact objects electromagnetic mass models

Superperiodicity,chaos and coexisting orbits of ion-acoustic waves in a four-component nonextensive plasma

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Communications in Theoretical Physics 2020年第11期72卷 87-98页

作者： Asit Saha Jharna Tamang Guo-Cheng Wu Santo banerjee Department of Mathematics Sikkim Manipal Institute of TechnologySikkim Manipal UniversityMajitarRangpoEast-Sikkim 737136India Data Recovery Key Laboratory of Sichuan Province College of Mathematics and Information ScienceNeijiang Normal UniversityNeijiang 641100China Department of Mathematical Sciences "Giuseppe Luigi Lagrange"Politecnico di TorinoCorso Duca degli Abruzzi 24TorinoItaly

Superperiodicity,chaos and coexisting orbits of ion-acoustic waves(IAWs)are studied in a multi-component plasma consisting of fluid ions,q-nonextensive cold and hot electrons and Maxwellian hot *** significant impacts of the system parameters on superperiodic and nonlinear periodic IAWs are *** an external periodic perturbation various types of quasiperiodic and chaotic features for IAWs are studied in different parametric ranges through time series’plots,phase spaces and Lyapunov *** has been observed that there exist some coexisting orbits for *** orbits for IAWs in a classical electron-positron-ion plasma system are reported.

关键词： dynamical system supernonlinear periodic wave quasiperiodicity multistability

Dry sliding tribological behavior of AZ31-WC nano-composites

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Journal of Magnesium and Alloys 2019年第2期7卷 315-327页

作者： Sudip banerjee Suswagata Poria Goutam Sutradhar Prasanta Sahoo Department of Mechanical Engineering Jadavpur UniversityKolkata 700032India

The present study investigates the effect of WC nano-particles on tribological behavior of magnesium based nanocomposites for varying wt%of WC(0.5,1,1.5 and 2 wt%).Nanocomposites are fabricated using ultrasonic vibration assisted stir casting *** microscopy,scanning electron microscopy and energy dispersive x-ray patterns are used to characterize the base alloy and fabricated *** values of as-cast composites are obtained through Vicker’s micro-hardness *** and wear behavior of fabricated composites are studied using pin-on-disk type tribotester at room temperature under dry sliding *** load range is 10-40 N while sliding speed range is 0.1-0.4 m/*** of Mg-composites confirms particle inclusion as well as better microstructural integrity with increase in *** value of composites increases with increase in the amount of WC *** and friction behavior of base matrix are also enhanced due to incorporation of WC *** wear mechanisms occurring at the contact surfaces are ascertained through SEM images and EDAX *** in the tested surface is also identified through SEM and *** yields better tribological behavior in composites.

关键词： Mg-WC nanocomposites Ultrasonic vibration Stir-casting Wear Friction

Effect of optical illumination on DDR IMPATT diode at 36 GHz

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Journal of Semiconductors 2017年第11期38卷 48-54页

作者： Atanu banerjee M.Mitra MCKV Institute of Engineering 243 G T Road (N) Liluah Howrah WB-711204 India Indian Institute of Engineering Science and Technology Shibpur Howrah WB-711103 India

A reverse biased p-n junction diode with proper resonant cavity and boundary conditions is able to generate rf power and shows normal DC and small signal properties designed with semiconductor materials like 4H-SiC, GaAs, InP, Si-based DDR IMPATT structure at Ka band with dark condition. But when it is exposed to optical illumination through a proper optical window for both top mounted（TM） and flip chip（FC） configuration,it shows the influence on the oscillator performances in that band of frequency. The simulated results are analyzed for 36 GHz window frequency in each of the diodes and relative differences are found in power output and frequency of all these diodes with variable intensities of illumination. Finally it is found that optical control has immense effect in both FC and TM mode regarding the reduction of output power and shifting of operating frequency from which optimization is done for the best optically sensitive material for IMPATT diode.

关键词： optical modulation flip chip structure top mounted structure window frequency DDR IMPATT diode

Influence of various shapes of nanoparticles on unsteady stagnation-point flow of Cu-H_(2)O nanofluid on a flat surface in a porous medium:A stability analysis

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Chinese Physics B 2022年第4期31卷 404-413页

作者： Astick banerjee Krishnendu Bhattacharyya Sanat Kumar Mahato Ali J.Chamkha Department of Mathematics Sidho-Kanho-Birsha UniversityPurulia 723104India Department of Mathematics Institute of ScienceBanaras Hindu UniversityVaranasi 221005India Faculty of Engineering Kuwait College of Science and TechnologyDoha DistrictKuwait

The nanofluid and porous medium together are able to fulfill the requirement of high cooling rate in many engineering ***,here the impact of various shapes of nanoparticles on unsteady stagnation-point flow of Cu-H_(2)O nanofluid on a flat surface in a porous medium is ***,the thermal radiation and viscous dissipation effects are *** problem governing partial differential equations are converted into self-similar coupled ordinary differential equations and those are numerically solved by the shooting *** computed results can reveal many vital findings of practical ***,dual solutions exist for decelerating unsteady flow and for accelerating unsteady and steady flows,the solution is *** presence of nanoparticles affects the existence of dual solution in decelerating unsteady flow only when the medium of the flow is a porous *** different shapes of nanoparticles are not disturbing the dual solution existence range,though it has a considerable impact on thermal conductivity of the *** shapes of nanoparticles act differently to enhance the heat transfer characteristics of the base fluid,i.e.,the water *** the other hand,the existence range of dual solutions becomes wider for a larger permeability parameter related to the porous *** the cooling rate of the heated surface,it rises with the permeability parameter,shape factor(related to various shapes of Cu-nanoparticles),and radiation *** surface drag force becomes stronger with the permeability ***,with growing values of nanoparticle volume fraction,the boundary layer thickness(BLT)increases and the thermal BLT becomes thicker with larger values of shape *** decelerating unsteady flow,the nanofluid velocity rises with permeability parameter in the case of upper branch solution and an opposite trend for the lower branch is *** thermal BLT is thicker with radiation *** to the ex

关键词： Cu-H_(2)O nanofluid various shapes of nanoparticles unsteady stagnation-point flow dual solutions stability analysis

Tracking sources and paleotectonic settings of Mesozoic sandstones in interlinked rift basins of western India:An integrated approach using petrography and heavy mineral chemistry

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Journal of Palaeogeography 2022年第2期11卷 173-193页

作者： Pawan Kumar Rajak Angana Chaudhuri Naraga Prabhakar Santanu banerjee Department of Earth Sciences Indian Institute of Technology BombayMumbai 400076India

Based on integration of field,petrographic and heavy mineral chemical data,this study highlights the source and tectonic setting of the Mesozoic sandstones of Kutch,Saurashtra,Narmada and Cambay basins at the western margin of India,formed by the progressive splitting of the eastern *** Kutch Basin is dominated by arkosic sandstone,whereas Saurashtra,Narmada and Cambay basins show the predominance of sub-arkose and *** modal analyses of framework grains in Kutch sandstones indicate basement uplift and transitional continent *** contrast,the sandstones of Saurashtra,Narmada and Cambay basins bear imprints of recycled orogenic and craton interior *** presence of abraded and detrital quartz overgrowth and rounded zircons in most sandstones reveal the recycling of sediments in these *** and rutile mineral compositions constrain the possible lithology of source *** tourmaline mineral chemistry(Ca-Fe_(tot)-Mg plot)suggests the derivation of sediments from various sources,including Li-poor granitoids associated with pegmatites,aplites,Ca-poor metapelites,metapsammites and quartz-tourmaline-rich granitic *** compositions of rutile grains(Cr *** plot)in sandstones indicate metapelitic *** gamut of all mineral chemical data supports the predominance of sediment sources from quartzo-feldspathic rocks with minor inputs from mafic *** on available paleocurrent data and correlation of source compositions,we infer that the Mesozoic sediments of Kutch,Saurashtra,Narmada and Cambay basins were primarily sourced by various lithologies of the Aravalli *** Narmada Basin possibly received additional sediment input from the Bundelkhand Craton.

关键词： Mesozoic sandstones Rift basins Tourmaline chemistry Rutile chemistry Kutch Basin Saurashtra Basin Cambay Basin Narmada Basin