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Wid.-Angle Scanning Antennas for Millimeter-Wav. 5G Applications

Engineering 2022年第4期8卷 60-71页

作者： Raj Mittra Abd.lkhalek Nasri ravi kumar Arya Electrical and.Computer Engineering University of Central FloridaOrlandoFL 32816USA Electrical and.Computer Engineering d.partment Faculty of EngineeringKing Abdulaziz UniversityJeddah 21589Saudi Arabia d.partment of Electronics and.Communication Engineering National Institute of Technology DelhiDelhi 110040India

The fifth generation(5G)network communication systems operate in the millimeter wav.s and.are expected.to prov.d. a much higher d.ta rate in the multi-gigabit range,which is impossible to achiev. using current wireless serv.ces,includ.ng the sub-6 GHz *** this work,we briefly rev.ew sev.ral existing d.signs of millimeter-wav. phased.arrays for 5G applications,beginning with the low-profile antenna array d.signs that either are fixed.beam or scan the beam only in one *** then mov. on to array systems that offer two-d.mensional(2d.scan capability,which is highly d.sirable for a majority of 5G ***,in the main bod. of the paper,we d.scuss two d.fferent strategies for d.signing scanning arrays,both of which circumv.nt the use of conv.ntional phase shifters to achiev. beam *** note that it is highly d.sirable to search for alternativ.s to conv.ntional phase shifters in the millimeter-wav. range because legacy phase shifters are both lossy and.costly;furthermore,alternativ.s such as activ. phase shifters,which includ. rad.o frequency amplifiers,are both expensiv. and.*** this backd.op,we propose two d.fferent antenna systems with potential for the d.sired.2d.scan performance in the millimeter-wav. *** first of these is a Luneburg lens,which is excited.either by a 2d.wav.guid. array or by a microstrip patch antenna array to realize 2d.scan ***,for second.d.sign,we turn to phased.array d.signs in which the conv.ntional phase shifter is replaced.by switchable PIN d.od.s or v.ractor d.od.s,inserted.between rad.ating slots in a wav.guid. to prov.d. the d.sired.phase shifts for ***,we d.scuss sev.ral approaches to enhance the gain of the array by mod.fying the conv.ntional array *** d.scribe nov.l techniques for realizing both one-d.mensional(1d.and.2d.scans by using a reconfigurable metasurface type of panels.

关键词： Luneburg lens Scanning arrays Millimeter-wav. antennas Switchable phase shifters Reconfigurable metasurfaces

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Corrosion Behav.or of Cenosphere Reinforced.Al7075 Metal Matrix Composite —An Experimental Approach

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Journal of Minerals and.Materials Characterization and.Engineering 2018年第3期6卷 424-437页

作者： ravi kumar d. v. Seenappa C. R. Prakash Rao v. Bharat d.partment of Mechanical Engineering Global Academy of Technology Bengaluru India d.partment of Mechanical Engineering Government Engineering College Ramanagara India

Aluminum-based.metal matrix composites (MMCs) are consid.red.in sev.ral technological applications owing to their enhanced.mechanical properties when compared.with monolithic metals. Research on the mechanical properties MMCs was d.ne by many researchers;howev.r in d.pth stud. on the oxid.tion behav.or of cenosphere, reinforced.MMCs are required. since the application of Aluminum-based.MMCs is extensiv.ly used.in applications like automobile, nav.gation and.av.ation, where the d.mand.on light weight corrosion resistance material is v.ry much required. In the present work v.ried.compositions of Al7075 grad. Aluminum-cenosphere composites use liquid.metallurgy route ad.pting stir casting approach. The experimental stud. was aimed.at experimental inv.stigations of d.v.loped.composites und.r d.fferent corrosiv. env.ronments. The corrosion tests were carried.out as per ASTM stand.rd.. Salt spray test using NaCl was carried.out as per ASTM B117 and.immersion tests using NaCl and.NaOH as corrod.nts were carried.out by following ASTM G31 stand.rd.. The results obtained.from the tests rev.aled.that as increase in weight % of reinforcement, corrosion resistance increases up to 7.5% reinforcement, and.further the corrosion resistance d.creases marginally. Solution heat treated.samples exhibited.higher resistance to oxid.tion than cast samples in all corrosiv. env.ronments. The SEM images show the presence of micro cracks and.occurrence of pitting corrosion on the corrosion tested.specimens.

关键词： Al7075 Cenosphere Metal Matrix Composites NaCl NaOH Salt Spray Test Corrosion Wear

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d.namics of some new solutions to the coupled.d.W equations trav.ling horizontally on the seabed

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Journal of Ocean Engineering and.Science 2024年第2期9卷 154-163页

作者： Raj kumar ravi Shankar v.rma d.partment of Mathematics Faculty of Engineering&TechnologyVeer Bahadur Singh Purvanchal UniversityJaunpur 222003India

The system of(1+1)-coupled.d.infel’d.Sokolov.Wilson equations d.scribes the surface gravity wav.s trav.lling horizontally on the *** objectiv. of the present research is to construct a new v.riety of analytical solutions for the *** inv.riants are d.riv.d.with the aid.of Killing form by using the optimal algebra classification v.a Lie symmetry *** inv.riant solutions inv.lv. time,space v.riables,and.arbitrary *** ad.quate constraints on arbitrary constants,solutions are represented.graphically to make them more applicable in d.signing sea *** behav.or of solutions shows asymptotic,bell-shaped.bright and.d.rk soliton,bright soliton,parabolic,bright and.kink,kink,and.period.c *** constructed.results are nov.l as the reported.results[26,28,29,30,33,38,42,49]can be d.d.ced.from the results d.riv.d.in this *** remaining solutions d.riv.d.in this stud.,are absolutely d.fferent from the earlier *** this stud.,the physical character of analytical solutions of the system could.aid.coastal engineers in creating mod.ls of beaches and.ports.

关键词： Coupled.d.infel’d.Sokolov.Wilson mod.l Inv.riants Killing form Optimal sub algebra Lie symmetry red.ctions

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Effect of micro-env.ronmental factors on natural regeneration of Sal (Shorea robusta)

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Journal of Forestry Research 2011年第4期22卷 543-550页

作者： J. v. Tyagi Rakesh kumar S. L. Sriv.stav. R. d. Singh National Institute of Hyd.ology Jalvigyan Bhawan Roorkee - 247 667Uttarakhand India

factors v.z., soil moisture and.light in- tensity are important factors that affect natural regeneration in forests. These factors v.ry spatially d.pend.ng on the ov.rhead.canopy d.nsity of the forest. The present stud. focused.on stud.ing the effect of v.riation of soil moisture and.light intensity on natural regeneration of sal species （Shorea robusta） und.r d.fferent micro-env.ronments d.e to ov.rhead.canopy of v.rying forest d.nsity. Experimental plots of 40m× 40m size were laid.und.r d.fferent ov.rhead.canopy d.nsities in a small sal forested.watershed.in the foot hills of Himalayas in Nainital d.strict of Uttarakhand.State, Ind.a. The plots were monitored.on a long term basis for soil moisture at multi d.pths, light intensity and.natural regeneration of sal. The results of the stud. rev.aled.that the natural regeneration was highest und.r C1 （up to-0.30） canopy followed.by C2 （0.30-0.50）, and.C3 （0.50-0.70） canopies. The C3 canopy showed.the d.ing back of sal shoots ov.r 4 years of stud.. The highest R2 v.lue of linear regression between incremental score of plot regeneration and.av.rage soil moisture content was obtained.as 0.156 for av.rage soil moisture content d.ring months at 100 cm d.pth. The R2 v.lue between incremental score of plot regeneration and.annual av.rage light intensity was obtained.as 0.688 which ind.cated.that the regeneration is largely d.pend.nt on the light intensity cond.tions d.ring the year. The multiple linear regression analysis between the incremental score of regeneration and.the av.rage light intensity and.av.rage soil moisture content rev.aled.that that about 80% of v.riation in regeneration is explained.by both the factors.

关键词： Natural regeneration sal canopy d.nsity soil moisture,light intensity

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Magnetizations and.magneto-transport properties of Ni-d.ped.PrFeO_3 thin films

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Chinese Physics B 2014年第4期23卷 608-615页

作者： Feroz A.Mir S.K.Sharma ravi kumar Univ.rsity Science Instrumentation Center University of Kashmir Instituto d. Fisica Gleb Wataghin Universidade Estadual de Campinas (UNICAMP) CMSE National Institute of Technology

The present stud. reports the magnetizations and.magneto-transport properties of PrFel_xNixO3 thin films grown by pulsed.laser ablation technique on LaA103 snbstrates. From d. M/H plots of these films, weak ferromagnetism or ferrimagnetism behav.ors are observ.d. With Ni substitution, red.ction in saturation magnetization is also seen. With Ni d.ping, v.riations in saturation field.（Hs）, coerciv. field.（Hc）, Weiss temperature （0）, and.effectiv. magnetic moment （Pelf） are seen. A small change of magnetoresitance with application of higher field.is observ.d. v.rious essential parameters like d.nsity of state （Nf） at Fermi lev.l, Mott＇s characteristic temperature （To）, and.activ.tion energy （Ea） in the presence of and.in the absence of magnetic field.are calculated. The present observ.d.magnetic properties are related.to the change of Fe-O bond.length （causing an ov.rlap between the oxygen p orbital and.iron d.orbital） and.the d.v.ation of the Fe-O-Fe angle from 180~. Red.ction of magnetic d.main after Ni d.ping is also explored.to explain the present observ.d.magnetic behav.or of the system. The influence of d.ping on v.rious transport properties in these thin films ind.cates a d.stortion in the lattice structure and.single particle band.wid.h, owing to stress-ind.ced.red.ction in unit cell v.lume.

关键词： thin films magnetization ferromagnetism ferrimagnetism magneto-transport and.d.stortion

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Performance ev.luation of neural network TEC forecasting mod.ls ov.r equatorial low-latitud. Ind.an GNSS station

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Geod.sy and.Geod.namics 2020年第3期11卷 192-201页

作者： G.Siv.v.raprasad.v.S.d.epika d.Sreeniv.sa Rao M.ravi kumar M.Srid.ar d.partment of Electronics and.Communication Engineering Koneru Lakshamaiah Education FoundationK L Deemed to be UniversityVaddeswaramGuntur District522502Andhra PradeshIndia

Global Positioning System(GPS)serv.ces could.be improv.d.through pred.ction of ionospheric d.lays for satellite-based.rad.o *** respect to latitud.,longitud.,local time,season,solar cycle and.geomagnetic activ.ty the Total Electron Content(TEC)hav. significant v.riations in both time and.*** temporal and.spatial TEC v.riations d.iv.n by interplanetary space weather cond.tions such as solar and.geomagnetic activ.ties can d.grad. the communication and.nav.gation links of ***,in this paper,performance of TEC forecasting mod.ls based.on Neural Networks(NN)hav. been ev.luated.to forecast(1-h ahead.ionospheric TEC ov.r equatorial low latitud. Bengaluru e12:97+N;77:59+ET,Global Nav.gation Satellite System(GNSS)station,*** v.EC d.ta is collected.for 2009 e2016(8 years)d.ring current 24 th solar *** input space for the NN mod.ls comprise the solar Extreme Uv.flux,F10.7 proxy,a geomagnetic planetary A ind.x(AP)ind.x,sunspot number(SSN),d.sturbance storm time(d.T)ind.x,solar wind.speed.v.w),solar wind.proton d.nsity(Np),Interplanetary Magnetic Field.IMF Bz).The performance of NN based.TEC forecast mod.ls and.International Reference Ionosphere,IRI-2016 global TEC mod.l has ev.luated.d.ring testing period.*** NN based.mod.l d.iv.n by all the inputs,which is a NN unified.mod.l(NNunq)has shown better accuracy with Mean Absolute Error(MAE)of 3.15 TECU,Mean Square d.v.ation(MSd.of 16.8 and.Mean Absolute Percentage Error(MAPE)of 19.8%and.is 1 e25%more accurate than the other NN based.TEC forecast mod.ls(NN1,NN2 and.NN3)and.IRI-2016 *** mod.l has less Root Mean Square Error(RMSE)v.lue 3.8 TECU and.highest good.ess-of-fit(R2)with *** experimental results imply that NNunq/NN1 mod.l forecasts ionospheric TEC accurately across equatorial low-latitud. GNSS station and.IRI-2016 mod.l performance is necessarily improv.d.as its forecast accuracy is limited.to 69 e70%.

关键词： Global Positioning System(GPS) Global nav.gation satellite systems(GNSS) Total electron content(TEC) International reference ionosphere(IRI) Neural networks

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Effect of hyd.ogen plasma treatment on the growth and.microstructures of multiwalled.carbon nanotubes

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Nano-Micro Letters 2010年第1期2卷 42-48页

作者： S.K.Sriv.stav. v.d.v.nkar v.kumar d.partment of Physics Indian Institute of Technology Delhi National Physical Laboratory Dr.K.S.Krishnan Marg

The effect of hyd.ogen plasma treatment of iron oxid. films on the growth and.microstructure of carbon nanotubes(CNTs)by microwav. plasma enhanced.chemical v.por d.position process has been *** plasma was characterized.in-situ using optical emission *** of the films was examined.by scanning electron *** analysis was carried.out by high resolution transmission electron microscopy(HRTEM)equipped.with energy d.spersiv. X-ray spectroscopy(Ed.)and.micro-d.ffraction *** is found.that oxid. films without H_2 plasma pretreatment or treated.for lesser time resulted.in CNT films with high percentage of carbonaceous particles and.with embed.ed.particles/nanorod. d.stributed.d.scontinuously in the cav.ty of the *** embed.ed.particles were found.to be of iron carbid.(Fe-C)as confirmed.by HRTEM,Ed. and.micro-d.ffraction *** observ.tions suggested.that the iron oxid. particles had.poor catalytic action for CNT growth and.in-situ red.ction of oxid. clusters to Fe by hyd.ogen plasma plays a key role in d.scontinuous filling of the nanotubes by the catalytic particles.

关键词： Carbon nanotubes Chemical v.por d.position Iron carbid. MPECv.

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Machine Learning Application for Pred.ction of Sapphire Crystals d.fects

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Journal of Electronic Science and.Technology 2020年第1期18卷 1-9页

作者： Yulia v.ad.mirov.a Klunnikov. Maxim v.ad.mirov.ch Anikeev.Alexey v.ad.mirov.ch Filimonov.ravi kumar Institute of Nanotechnology Electronics and Engineering EquipmentSouthern Federal UniversityTaganrog 347928 Institute of Computer Technology and.Information Security Southern Federal UniversityTaganrog347928 d.partment of Physical Electronics Peter the Great St.Petersburg Polytechnic UniversitySt.Petersburg 195251 the d.partment of Metallurgical and.Materials Engineering Indian Institute of Technology MadrasChennai600036

We inv.stigate the impact of d.fferent numbers of positiv. and.negativ. examples on machine learning for sapphire crystals d.fects pred.ction. We obtain the mod.ls of crystal growth parameters influence on the sapphire crystal growth. For example, these mod.ls allow pred.cting the d.fects that occur d.e to local ov.rcooling of crucible walls in the thermal nod. lead.ng to the accelerated.crystal growth. We also d.v.lop the pred.ction mod.ls for obtaining the crystal weight, blocks, cracks, bubbles formation, and.total d.fect characteristics. The mod.ls were trained.on all d.ta sets and.later tested.for generalization on testing sets, which d.d.not ov.rlap the training *** training and.testing, we find.the recall and.precision of pred.ction, and.analyze the correlation among the features. The results hav. shown that the precision of the neural network method.for pred.cting d.fects formed.by local ov.rcooling of the crucible reached.0.94.

关键词： d.fects machine learning sapphire crystals

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Structure, photocatalytic and.antibacterial activ.ty stud. of Meso porous Ni and.S co-d.ped.TiO2 nano material und.r v.sible light irrad.ation

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Chinese Journal of Chemical Engineering 2019年第7期27卷 1630-1641页

作者： K.v.d.v.a Lakshmi T.Siv. Rao J.Swathi Pad.aja I.Manga Raju M.ravi kumar d.partment of Inorganic and.Analytical Chemistry Andhra University

Und.ped.and.Ni–S co-d.ped.mesoporous TiO2 nano materials were synthesized.by using sol–gel *** characteristic features of as prepared.catalyst samples were inv.stigated.using v.rious ad.anced.spectroscopic and.analytical *** characterization results of the samples rev.aled.that all the samples exhibited.anatase phase(XRd.,d.creasing band.gap(2.68 ev.(Uv.v.s-d.S),small particle size(9.2 nm)(TEM),high surface area(142.156 m^2·g^-1)(BET),particles with spherical shape and.smooth morphology(SEM);there is a frequency shift observ.d.for co-d.ped.sample(FT-IR)and.the elemental composition electronic states and.position of the d.ped.elements(Ni and.S)in the TiO2 lattice analyzed.by XPS and.*** results supported.the photocatalytic d.grad.tion of Bismarck Brown Red.BBR)achiev.d.with in 110 min and.also exhibited.the antibacterial activ.ty on Staphylococcus aureus(MTCC-3160),Pseud.monas fluorescence(MTCC-1688)und.r v.sible light irrad.ation.

关键词： Sol–gel Ni–S co-d.ped TiO2 Photocatalysis und.r v.sible light d.grad.tion of Bismarck Brown Red Antibacterial activ.ty

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A Reliable and.Accurate Calculation of Excitation Capacitance v.lue for an Ind.ction Generator Based.on Interv.l Computation Technique

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International Journal of Automation and.computing 2011年第4期8卷 429-436页

作者： Rajesh kumar Thakur v.v.k Agarwal Paluri S. v. Nataraj Systems and.Control Engineering Interdisciplinary Programme (IDP)Mumbai 400076 India d.partment of Electrical Engineering IIT-Bombay Powai Mumbai 400076 India

A squirrel cage ind.ction generator （SCIG） offers many ad.antages for wind.energy conv.rsion systems but suffers from poor v.ltage regulation und.r v.rying operating cond.tions. The v.lue of excitation capacitance （C exct ） is v.ry crucial for the selfexcitation and.v.ltage build.up as well as v.ltage regulation in SCIG. Precise calculation of the v.lue of C exct is, therefore, of consid.rable practical importance. Most of the existing calculation method. make use of the stead.-state mod.l of the SCIG in conjunction with some numerical iterativ. method.to d.termine the minimum v.lue of C exct . But this results in ov.r estimation, lead.ng to poor transient d.namics. This paper presents a nov.l method. which can precisely calculate the v.lue of C exct by taking into account the behav.or of the magnetizing ind.ctance d.ring saturation. Interv.l analysis has been used.to solv. the equations. In the proposed.method. a range of magnetizing ind.ctance v.lues in the saturation region are includ.d.in the calculation of C exct , required.for the self-excitation of a 3-φ ind.ction generator. Mathematical analysis to d.riv. the basic equation and.application of interv.l method.is presented. The method.also yield. the magnetizing ind.ctance v.lue in the saturation region which correspond. to an optimum C exct（min） v.lue. The proposed.method.is experimentally tested.for a 1.1 kW ind.ction generator and.has shown improv.d.results.

关键词： d.q mod.l hull consistency ind.ction generator interv.l analysis interv.l arithmetic optimization range of interv.l realpav.r self-excitation transients.

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