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Graphene foam resonators:Fabrication and characterization

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Nano Research 2022年第1期15卷 225-229页

作者： Yahav Ben-Shimon siva kreddy Assaf Ya'akobovitz Department of Mechanical Engineering Faculty of Engineering SciencesBen-Gurion University of the NegevIsrael

Three-dimensional graphene foams(GFs)benefit from a large surface area and unique physical *** present here the first-ever miniaturized GF-based *** developed a simple yet reliable fabrication process,in which GFs are synthesized and assembled on a cavity to form suspended GF *** electrostatically excited these devices and analyzed their resonance and ring-down *** observed significant energy dissipation,as the quality factor of the devices was in the order of several ***,we investigated the influence of temperature on the operation of the devices and found that high temperatures mechanically soften the resonators but also considerably enhance energy ***,our devices demonstrated a mode-coupling of a resonance mode and a mode having twice its ***,this work paves the way toward the development of novel GF resonators that could be integrated into future devices,such as GF-based nano-electromechanical sensors,electrical circuits,and oscillators.

关键词： energy dissipation graphene foam micro/nano electromechanical systems three-dimensional graphene resonators

Effect of Diffuser Vane Shape on the Performance of a Centrifugal Compressor Stage

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Journal of Thermal Science 2014年第2期23卷 127-132页

作者： T Ch siva reddy GV Ramana Murty MVSSSM Prasad Sreenidhi Institute of Science and Technology GhatkesarHyderabadA.P.India Vasavi College of Engineering Hhyderabad

The present paper reports the results of experimental investigations on the effect of diffuser vane shape on the performance of a centrifugal compressor stage. These studies were conducted on the chosen stage having a back- ward curved impeller of 500 turn tip diameter and 24.5 mm width and its design flow coefficient is Фd=0.0535. Three different low solidity diffuser vane shapes namely uncarnbered aerofoil, constant thickness flat plate and circular arc cambered constant thickness plate were chosen as the variants for diffuser vane shape and all the three shapes have the same thickness to chord ratio （t/c=0.1）. Flow coefficient, polytropic efficiency, total head coeffi- cient, power coefficient and static pressure recovery coefficient were chosen as the parameters for evaluating the effect of diffuser vane shape on the stage performance. The results show that there is reasonable improvement in stage efficiency and total head coefficient with the use of the chosen diffuser vane shapes as compared to conven- tional vaneless diffuser. It is also noticed that the aero foil shaped LSD has shown better performance when com- pared to flat plate and circular arc profiles. The aerofoil vane shape of the diffuser blade is seen to be tolerant over a considerable range of incidence.

关键词： Centrifugal compressor Vaneless diffuser Low solidity diffuser

Finite element analysis on transient magnetohydrodynamic(MHD)free convective chemically reacting micropolar fluid flow past a vertical porous plate with Hall current and viscous dissipation

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Propulsion and Power Research 2018年第4期7卷 353-365页

作者： siva reddy Sheri M.D.Shamshuddin Department of Mathematics.G1TAM University Hyderabad CampusTelangana 502329India Department of Mathematics.Vaagdevi College of Engineering WarangalTelangana 506005India

This article deals with boundary layer analysis of magnetohydrodynamics on an unsteady chemically reactive micropolar rotating fluid flow past a semi-infinite vertical plate with been developed under Boussinesq *** governing partial differential equations are transformed into a set of coupled partial differential equations using suitable dimensionless *** resultant equations are solved numerically using variational finite element method.A parametric study illustrating the influence of different pertinent parameters is performed and the numerical results for translational velocity,microrotation velocity,temperature and concentration distributions near the boundary layers are discussed and presented graphically for the parametric ***,the skin-friction,wall couple stress,surface heat transfer and mass transfer rate dependency on the emerging thermo-physical parameters are also *** finite element code is benchmarked with the results reported in the literature to check the validity and accuracy under some limiting cases and excellent agreement with published solutions is achieved.

关键词： Hall current Chemical reaction Micropolar fluid Magnetohydrodynamic(MHD) Finite elementmethod(FEM)

Microwave synthesis and spectroscopic characterization of manganese oxalate nanocrystals

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Particuology 2013年第3期11卷 340-345页

作者： S.Lakshmi reddy G.Udayabashkar reddy R.Ramasubba reddy G.siva reddy Ray L.Frostc Tamio Endo Department of Physics Sri Venkateswara Degree College Department of Chemistry Sri Venkateswara University School of Chemistry Physics and Mechanical EngineeringScience and Engineering FacultyQueensland University of Technology Faculty of Engineering Mie University

The microwave synthesis of MnC204.2H2O nanoparticles was performed through the thermal double decomposition of oxalic acid dihydrate （C2H204.2H20） and Mn（OAc）2.4H2O solutions using a CATA-2R microwave reactor. Structural characterization was performed using X-ray diffraction （XRD）, particle size and shape were analyzed using transmission electron microscopy （TEM）. The chemical in the structures was investigated using electron paramagnetic resonance （EPR） as well as optical absorption spectra and near-infrared （NIR） spectroscopies. The nanocrystals produced with this method were pure and had a distorted rhombic octahedral *** oxalate

关键词： Lindbergite Electron paramagnetic resonance Optical absorption and NIR spectra Mn(ll) Water fundamentals

Novel continuous single-step synthesis of nitrogen-modified TiO_2 by flame spray pyrolysis for photocatalytic degradation of phenol in visible light

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Journal of Materials Science & Technology 2018年第9期34卷 1494-1502页

作者： Thirupathi Boningari siva Nagi reddy Inturi Makram Suidan Panagiotis G.Smirniotis Chemical Engineering Program College of Engineering & Applied Science University of Cincinnati Environmental Engineering College of Engineering & Applied Science University of Cincinnati

A novel rapid and continuous process has developed for the synthesis of nitrogen-doped TiO2（N-TiO2）with flame spray pyrolysis（FSP） method. The nitrogen incorporation into TiO2 was achieved by a facile modification（addition of dilute nitric acid） in the precursor for the synthesis. The catalysts were characterized by X-ray diffraction, Raman spectroscopy, transmission electron microscopy, diffuse reflectance spectroscopy, and X-ray photoelectron spectroscopy. The doping of nitrogen into the TiO2 was confirmed by X-ray photoelectron spectroscopy（XPS） and energy dispersive X-ray（EDX） spectroscopy. The UV-vis spectra of the modified catalysts（with primary N source） exhibited band-gap narrowing for 4 N-TiO2 with band gap energy of 2.89 eV, which may be due to the presence of nitrogen in TiO2 structure. The introduction of secondary N-source（urea） into TiO2 crystal lattice results in additional reduction of the band gap energy to 2.68 eV and shows a significant improvement of visible light absorption. The N-TiO2 nanoparticles modified by using secondary N-source showed significant photocatalytic activity under visible light much higher than TiO2. The higher activity is attributed to the synergetic interaction of nitrogen with the TiO2 lattice. The lowering of the band-gap energy for the flame made N-doped TiO2 materials implies that the nitrogen doping in TiO2 by aerosol method is highly effective in extending the optical response of TiO2 in the visible region. The nitrogen atomic percentage has increased monotonically（0.09%-0.15%）with the increase in primary nitrogen source（nitric acid）, and significantly boosted to 0.97% when secondary nitrogen source（urea） was introduced. The highest rate of phenol degradation was obtained for catalysts with secondary N source due to increase in N content in the catalyst.

关键词： Flame spray pyrolysis(FSP) Titania (TiO2) Visible-light-induced Liquid phase Phenol photodegradation

One-dimensional numerical investigation on multicylinder gasoline engine fueled by micro-emulsions,CNG,and hydrogen in dual fuel mode

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Chinese Journal of Aeronautics 2023年第5期36卷 57-65页

作者： Ufaith QADIRI D.siva kRISHNA reddy Amjad ALI PASHA Mohammad IRFAN ALAM Department of Mechanical Engineering Sreenidhi UniversityYamnampetGhatkesar Hyderabad 501301India School of Mechanical Engineering SRM Institute of Science and TechnologyKattankulathurChennai 603203India Aerospace Engineering Department King Abdulaziz UniversityJeddah 21589Saudi Arabia Department of Aerospace Engineering VIT Bhopal UniversitySehore 466665India

This research work is the novel state-of-the-art technology performed on multi-cylinder SI engine fueled compressed natural gas,emulsified fuel,and hydrogen as dual *** work predicts the overall features of performance,combustion,and exhaust emissions of individual fuels based on AVL Boost simulation *** types of alternative fuels have been compared and *** results show that hydrogen produces 20%more brake power than CNG and 25%more power than micro-emulsion fuel at 1500 r/min,which further increases the brake power of hydrogen,CNG,and micro-emulsions in the range of 25%,20%,and 15%at higher engine speeds of 2500-4000 r/min,*** addition,the brake-specific fuel consumption is the lowest for 100%hydrogen,followed by CNG 100%and then micro-emulsions at 1500 r/*** 2500-5000 r/min,there is a significant drop in brake-specific fuel consumption due to a lean mixture at higher engine *** CO,HC,and NOx emissions significantly improve for hydrogen,CNG,and micro-emulsion *** fuel shows zero CO and HC emissions and is the main objective of this research to produce 0%carbon-based emissions with a slight increase in NOx emissions,and CNG shows 30%lower CO emissions than micro-emulsions and 21.5%less hydrocarbon emissions than micro-emulsion fuel at stoichiometric air/fuel ratio.

关键词： CNG Emissions Hydrogen Ignition Micro-emulsions Performance

A Fast and Highly Efficient Protocol for Reductive Amination of Aromatic Aldehydes Using NaBH4 and Isoxazole Amines in an Ionic Liquid Medium

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Chinese Journal of Chemistry 2011年第4期29卷 769-772页

作者： Eligeti, Rajanarendar Atthunuri, siva Rami reddy Samala, Raju Shaik, Firoz Pasha Govardhan reddy Department of Chemistry Kakatiya University Warangal 506009 Andhra Pradesh India

Reductive amination of aromatic aldehydes using NaBH4 and isoxazole amines is carried out in a Bronsted acidic ionic liquid 1 -methylimidazolium tetrafluoroborate [（HMIm）BF4]. The ionic liquid plays dual roles of solvent as well as catalyst for the efficixcellent yields without any undesired side product formation. The newly synthesized compoundsent transformation of aromatic aldehydes to heterocyclic substituted amines in e （3, 6 and 7） were characterized by IR, 1H NMR and mass spectral techniques.

关键词： ionic liquid green chemistry reductive amination 1-methylimidazolium tetrafluoroborate isoxazole amine

Expeditious method for the synthesis of novel 2,3,5,6-tetrahydrobenzo[g] [1,3,5]oxadiazocine-4-thiones linked with isoxazole

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Chinese Chemical Letters 2008年第12期19卷 1415-1418页

作者： E.Rajanarendar A.siva Rami reddy M.Srinivas Department of Chemistry Kakatiya UniversityWarangal 506009India

Synthesis of novel 3-aryl-5-（3,5-dimethylisoxazol-4-yl）-2,3,5,6-tetrahydrobenzo[g][1,3,5],oxadiazocine-4-thiones 5 has been accomplished from 3,5-dimethylisoxazol-4-amine 1 by condensation with salicylaldehydes, followed by reduction, treatment with aryl isothiocyanates and subsequent smooth ring closure via acetal formation in the presence of formaldehyde.

关键词： Isoxazolyl-2,3,5,6-tetrahydrobenzo[g]oxadiazocine-4-thiones Ring closure New methodology

Mechanical properties of Ni_(0.83)Co_(0.15)Cu_(0.02)Fe_(1.9)O_(4-δ)+PbZr_(0.52)Ti_(0.48)O_(3)particulate composites by composite oscillator technique and the correlation with the results of magnetoelectric properties

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Journal of Advanced Ceramics 2012年第4期1卷 317-326页

作者： M.Venkata RAMANA M.Penchal reddy N.Ramamanohar reddy B.S.MURTY k.V.siva kUMAR Shenhua SONG Shenzhen key Laboratory of Advanced Materials Department of Materials Science and EngineeringShenzhen Graduate SchoolHarbin Institute of TechnologyShenzhen 518055China Department of Physics Changwon National UniversityChangwonRepublic of Korea Ceramic Composite Materials Laboratory Department of PhysicsSri Krishnadevaraya UniversityAnantapur 515003India Nanotechnology Laboratory Department of Metallurgical and Materials EngineeringIndian Institute of TechnologyChennai 600036India

The xNi_(0.83)Co_(0.15)Cu_(0.02)Fe_(1.9)O_(4-δ)+PbZr_(0.52)Ti_(0.48)O_(3)(PZT)particulate magneto ferroelectric composites with x=0,0.1,0.2,0.3,0.4,0.5 and 0.6 mole fraction were prepared by conventional ceramic double sintering *** presence of two phases(perovskite structure of ferroelectric phase and spinal structure of ferromagnetic phase)was confirmed by X-ray *** magnetoelectric(ME)property of the particulate composites was determined at room temperature as a function of intensity of magnetic *** temperature variation of the longitudinal modulus(L)and the internal friction(Q−1)of these particulate composites at 104.3 kHz was studied in the wide temperature range 30-420℃.The temperature variation of the longitudinal modulus in each composition of these particulate composites showed two abrupt *** minimum coincided with the ferroelectric-paraelectric Curie transition temperature(θE)and the other with the ferromagnetic-paramagnetic Curie transition temperature(θM).The internal friction measurement also showed two sharp peaks in each composition corresponding to those temperatures where the minima were noticed in the temperature variation of the longitudinal modulus behaviour.

关键词： X-ray diffraction magnetoelectric effect piezoelectric coefficient internal friction Curie transition temperature