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International Journal of Smart and Nano Materials 2020年第1期11卷 38-46页

作者： ravi Kumar Cheedarala Jung Il Song Research Institute of Mechatronics Department of Mechanical EngineeringChangwon National UniversityUichang-guChangwon CityS.Korea

Contact electrification is a direct triboelectrification method for producing current through charge transfer when two different differentiated materials have brought into *** the first time,we developed a simple triboelectric nanogenerator(TENG)where the electronic charges were realized through contact separation mode between sand-polished Kapton(SPK)and Al ***,we demonstrated the energetic interfacial contact between these surfaces and observed satisfactory output *** novel SPK-TENG produced 40 V and 2.8μA,of open-circuit voltages(V_(oc))and short-circuit currents(Isc)at 4 Hz,***,the SPK-TENG was dramatically increased up the performance of TENG,up to 40% of V_(oc) and 42% of I_(sc),with respect to the Kapton film because the mobility of electrons is very high on the device surface compared to the other pristine Kapton *** fabricated SPK-TENGs were good candidates for satisfying the need for alternative contact separation mode TENGs.

关键词： Kapton contactelectrification K-Al TENG SPK-Al TENGs electron transfer mechanism

EDITORIAL:Now is the Time for Energy Materials Research to Save the Planet

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Energy & Environmental Materials 2021年第4期4卷 497-499页

作者： S.ravi P.Silva Advanced Technology Institute University of SurreyGuildfordUK

Linking Energy Supply and Energy Storage to the UN Sustainable Development Goals Our world has witnessed an unprecedented time in the last twelve months,with many activities coming to a standstill because of the COVID-19 *** all walks of life,the world will not be the same as it struggles for normality at present,with many sectors shut for extended periods of time and some businesses shutdown for ***,with all this upheaval.

关键词： Sustainable shutdown struggle

Optimization of Out-of-Band Emission Using Kaiser-Bessel Filter for UFMC in 5G Cellular Communications

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China Communications 2019年第8期16卷 15-23页

作者： ravi Sekhar Yarrabothu Usha Rani Nelakuditi Department of ECE VFSTR (Deem To Be University)

Across the world, we are currently witnessing the deployments of 4 G LTE-Advanced and the 5 G research is reaching its peak point. The 5 G research mainly concentrates on addressing some of the existing OFDM based LTE problems along with use of non-contiguous fragmented spectrum. Universal Filtered Multi Carrier(UFMC) has been considered as one of the candidate waveform for the 5 G communications because it provides robustness against the Inter Symbol Interference(ISI), and Inter Carrier Interference(ICI) and is suitable for low latency scenarios. In this paper, a novel approach is proposed to use Kaiser-Bessel filter based pulse shaping instead of standard Dolph-Chebyshev filter for UFMC based waveform to reduce the spectral leakage into nearby sub-bands. In this paper, UFMC system is simulated using MATLAB software, a comparative study for Dolph-Chebyshev and Kaiser-Bessel filters are performed and the results are also presented in terms of power spectrum density(PSD) analysis, Complementary Cumulative Distribution Function(CCDF) analysis, and Adjacent Channel Power Ratio(ACPR) analysis. The simulated results show a better power spectral density and lower sidebands for UFMC(Kaiser Based window), when compared with UFMC(Dolph-Chebyshev) and conventional OFDM.

关键词： 5G Dolph-Chebyshev filter Kaiser-Bessel filter OFDM UFMC

Near Optimal PID Controllers for the Biped Robot While Walking on Uneven Terrains

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International Journal of Automation and computing 2018年第6期15卷 689-706页

作者： ravi Kumar Mandava Pandu Ranga Vundavilli School of Mechanical Sciences Indian Institute of Technology (IIT) Bhubaneswar

The execution of the gaits generated with the help of a gait planner is a crucial task in biped locomotion. This task is to be achieved with the help of a suitable torque based controller to ensure smooth walk of the biped robot. It is important to note that the success of the developed proportion integration differentiation （PID） controller depends on the selected gains of the controller. In the present study, an attempt is made to tune the gains of the PID controller for the biped robot ascending and descending the stair case and sloping surface with the help of two non-traditional optimization algorithms, namely modified chaotic invasive weed optimization （MCIWO） and particle swarm optimization （PSO） algorithms. Once the optimal PID controllers are developed, a simulation study has been conducted in computer for obtaining the optimal tuning parameters of the controller of the biped robot. Finally, the optimal gait angles obtained by using the best controller are fed to the real biped robot and found that the biped robot has successfully negotiated the said terrains.

关键词： Biped robot staircase sloping surface proportion integration differentiation (PID) controller modified chaotic invasive weed optimization (MCIWO) & particle swarm optimization (PSO) algorithm.

Processing and characterization of polymer precursor derived silicon oxycarbide ceramic foams and compacts

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Journal of Advanced Ceramics 2013年第4期2卷 318-324页

作者： Srinivasan NEDUNCHEZHIAN ravindran SUJITH ravi KUMAR Materials Processing Section Department of Metallurgical and Materials EngineeringIndian Institute of Technology MadrasChennai 600036Tamil NaduIndia

This work focused on the fabrication of silicon oxycarbide ceramic(SiOC)foams as well as dense compacts using poly(hydridomethylsiloxane)(PHMS)as a polymer *** room-temperature cross-linking of PHMS was achieved by the addition of 1,4-diazabicyclo[2.2.2]octane(DABCO)with the release of hydrogen gas as a *** resulted in self-blowing of the polymer precursor at room temperature and thereby offered the possibility of producing SiOC foams without the need of any external blowing *** also reported the fabrication of crack-free silicon oxycarbide compacts by cold compaction and pyrolysis route using polyvinyl alcohol(PVA)as a processing ***-shaped pellets were pyrolysed at 1300℃in argon atmosphere with a ceramic yield of approximately 85%.Increased resistance to phase separation and crystallization up to 1400℃was attributed to the presence of large volume fraction of free carbon in the material which was confirmed by Raman spectroscopy.

关键词： silicon oxycarbide foams 1,4-diazabicyclo[2.2.2]octane(DABCO) self-blown polymer poly(hydridomethylsiloxane)(PHMS)

DeNOx Study in Diesel Engine Exhaust Using Barrier Discharge Corona Assisted by V_2O_5/TiO_2 Catalyst

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Plasma Science and Technology 2004年第4期6卷 2411-2415页

作者： B.S.Rajanikanth V.ravi Indian Institute of Science Bangalore 560012IndiaIndian Institute of ScienceBangalore 560012India

A plasma-assisted catalytic reactor was used to remove nitrogen oxides (NOx)from diesel engine exhaust operated under different load conditions. Initial studies were focused onplasma reactor (a dielectric barrier discharge reactor) treatment of diesel exhaust at varioustemperatures. The nitric oxide (NO) removal efficiency was lowered when high temperature exhaust wastreated using plasma reactor. Also, NO removal efficiency decreased when 45% load exhaust wastreated. Studies were then made with plasma reactor combined with a catalytic reactor consisting ofa selective catalytic reduction (SCR) catalyst, V_2O_5/TiO_2. Ammonia was used as a reducing agentfor SCR process in a ratio of 1:1 to NOx. The studies were focused on temperatures of the SCRcatalytic reactor below 200℃. The plasma-assisted catalytic reactor was operated well to remove NOxunder no-load and load conditions. For an energy input of 96 J/l, the NOx removal efficienciesobtained under no-load and load conditions were 90% and 72% respectively at an exhaust temperatureof 100 ℃.

关键词： non-thermal plasma DeNOx barrier discharge diesel exhaust

An automated water dispensing system for controlling fires in coal yards

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International Journal of Coal Science & Technology 2022年第2期9卷 220-228页

作者： Jeevan Jayasuriya Irene Moser ravi de Mel University of Sri Jayewardenepura GangodawilaNugegodaSri Lanka Swinburne University of Technology MelbourneVICAustralia

In spite of recent moves to wean the world of fossil fuels,coal remains the main source of power in many *** yards are prone to spontaneous ignition,a problem faced in every country that stores or transports *** on the environment-temperature,ventilation,and the rank of the coal-heating and self-ignition can be a longer or shorter process,but the possibility can never be entirely dismissed.A plethora of studies have modelled this oxidation behavior and proposed *** often,human intervention is necessary,which is both slow and dangerous for the frefghters *** this study,we propose to build a complete frefghting solution which is mounted on a number of towers sufcient to cover the area of an open coal yard,complete with *** tower includes an inexpensive infrared detector,a water dispenser and a controller programmed to identify areas of elevated temperature,and actuate the *** heat direction algorithm calculates the parameters to position the water dispenser so that it covers the area.A prototype has been built from inexpensive components to demonstrate the efectiveness at detecting and extinguishing arising fres,and a solution has been costed for the coal yard in the case *** work has been conducted in collaboration with the managers of the coal yard of a power plant.

关键词： Coal yard fre Fire detection Internet of things Spontaneous combustion detection Infrared heat detection

Wide-Angle Scanning Antennas for Millimeter-Wave 5G Applications

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Engineering 2022年第4期8卷 60-71页

作者： Raj Mittra Abdelkhalek Nasri ravi Kumar Arya Electrical and Computer Engineering University of Central FloridaOrlandoFL 32816USA Electrical and Computer Engineering Department Faculty of EngineeringKing Abdulaziz UniversityJeddah 21589Saudi Arabia Department of Electronics and Communication Engineering National Institute of Technology DelhiDelhi 110040India

The fifth generation(5G)network communication systems operate in the millimeter waves and are expected to provide a much higher data rate in the multi-gigabit range,which is impossible to achieve using current wireless services,including the sub-6 GHz *** this work,we briefly review several existing designs of millimeter-wave phased arrays for 5G applications,beginning with the low-profile antenna array designs that either are fixed beam or scan the beam only in one *** then move on to array systems that offer two-dimensional(2D)scan capability,which is highly desirable for a majority of 5G ***,in the main body of the paper,we discuss two different strategies for designing scanning arrays,both of which circumvent the use of conventional phase shifters to achieve beam *** note that it is highly desirable to search for alternatives to conventional phase shifters in the millimeter-wave range because legacy phase shifters are both lossy and costly;furthermore,alternatives such as active phase shifters,which include radio frequency amplifiers,are both expensive and *** this backdrop,we propose two different antenna systems with potential for the desired 2D scan performance in the millimeter-wave *** first of these is a Luneburg lens,which is excited either by a 2D waveguide array or by a microstrip patch antenna array to realize 2D scan ***,for second design,we turn to phased-array designs in which the conventional phase shifter is replaced by switchable PIN diodes or varactor diodes,inserted between radiating slots in a waveguide to provide the desired phase shifts for ***,we discuss several approaches to enhance the gain of the array by modifying the conventional array *** describe novel techniques for realizing both one-dimensional(1D)and 2D scans by using a reconfigurable metasurface type of panels.

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

Prevalence of advanced liver fibrosis and steatosis in type-2 diabetics with normal transaminases:A prospective cohort study

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World Journal of Gastroenterology 2021年第6期27卷 523-533页

作者： Jasbir Makker Hassan Tariq Kishore Kumar Madhavi ravi Danial Haris Shaikh Vivien Leung Umar Hayat Muhammad T Hassan Harish patel Suresh Nayudu Sridhar Chilimuri Division of Gastroenterology Department of MedicineBronxCare Health SystemBronxNY 10457United States KU School of Medicine-Wichita University of KansasWichitaKS 67214United States Department of Medicine BronxCare Health SystemBronxNY 10457United States

BACKGROUND Nonalcoholic fatty liver disease(NAFLD)and type-2 diabetes mellitus(T2DM)have an intricate bidirectional *** with T2DM,not only have a higher prevalence of non-alcoholic steatosis,but also carry a higher risk of progression to nonalcoholic *** still differ in their recommendations of screening for NAFLD among patients with *** To study the prevalence of NAFLD and advanced fibrosis among our patient population with *** During the study period(November 2018 to January 2020),59 adult patients with T2DM and 26 non-diabetic control group individuals were recruited *** with known significant liver disease and alcohol use were *** data and lab parameters were *** elastography was performed in all *** In the study group comprised of patients with T2DM and normal alanine aminotransferase levels(mean 17.8±7 U/L),81%had hepatic steatosis as diagnosed by *** hepatic fibrosis(stage F3 or F4)was present in 12%of patients with T2DM as compared to none in the control *** with T2DM also had higher number of individuals with grade 3 steatosis[45.8%vs 11.5%,(P<0.00001)and metabolic syndrome(84.7%vs 11.5%,P<0.00001)].CONCLUSION A significant number of patients with T2DM,despite having normal transaminase levels,have NAFLD,grade 3 steatosis and advanced hepatic fibrosis as measured by liver elastography.

关键词： Advanced liver fibrosis Diabetes Steatosis Normal transaminases Fatty liver disease Metabolic syndrome

A Two-stage Kalman Filter for Cyber-attack Detection in Automatic Generation Control System

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Journal of Modern Power Systems and Clean Energy 2022年第1期10卷 50-59页

作者： Ayyarao S.L.V.Tummala ravi Kiran Inapakurthi GMR Institute of Technology RajamSrikakulamAndhra PradeshIndia Raghu Engineering College DakamarriVisakhapatnamAndhra PradeshIndia

Communication plays a vital role in incorporating smartness into the interconnected power ***,historical records prove that the data transfer has always been vulnerable to *** these cyber-attacks are identified and cordoned off,they may lead to black-out and result in national security *** paper proposes an optimal two-stage Kalman filter(OTS-KF)for simultaneous state and cyber-attack estimation in automatic generation control(AGC)***/cyber-attacks are modeled as unknown inputs in the AGC *** types of cyber-attacks,i.e.,false data injection(FDI),data replay attack,denial of service(DoS),scaling,and ramp attacks,are injected into the measurements and estimated using *** the load variations of each area are seldom available,OTS-KF is reformulated to estimate the states and outliers along with the load variations of the *** proposed technique is validated on the benchmark two-area,three-area,and five-area power system *** simulation results under various test conditions demonstrate the efficacy of the proposed filter.

关键词： Cyber-security automatic generation control(AGC) load frequency control false data injection cyber-attack detection