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Projective Hilbert modules and sequential approximations

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Science China Mathematics 2025年第1期 137-168页

作者： Lawrence g.Brown Huaxin Lin Department of Mathematics Purdue University Department of Mathematics East China Normal University Department of Mathematics University of Oregon Shanghai Institute for Mathematics and Interdisciplinary Sciences

We show that when A is a separable C*-algebra,every countably generated Hilbert A-module is projective（with bounded module maps as morphisms）.We also study the approximate extensions of bounded module *** the case where A is a σ-unital simple C*-algebra with strict comparison,and every strictly positive lower semicontinuous affine function on quasitraces can be realized as the rank of an element in the Cuntz semigroup,we show that the Cuntz semigroup is equivalent to unitarily equivalent classes of countably generated Hilbert A-modules if and only if A has stable rank one.

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Frequency equation for the submicron CMOS ring oscillator using the first order characterization

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Journal of Semiconductors 2018年第5期39卷 64-69页

作者： Aravinda koithyar T.k.ramesh Department of Electronics and Communication Engineering Amrita School of Engineering

By utilizing the first order behavior of the device,an equation for the frequency of operation of the submicron CMOS ring oscillator is presented.A 5-stage ring oscillator is utilized as the initial design,with different Beta ratios,for the computation of the operating *** on,the circuit simulation is performed from 5-stage till 23-stage,with the range of oscillating frequency being 3.0817 and 0.6705 gHz *** is noted that the output frequency is inversely proportional to the square of the device length,and when the value of Beta ratio is used as 2.3,a difference of 3.64%is observed on an average,in between the computed and the simulated values of *** an outcome,the derived equation can be utilized,with the inclusion of an empirical constant in general,for arriving at the ring oscillator circuit’s output frequency.

关键词： ring oscillator stage delay SPICE model RC model second order effects

Polytypic transformations of aluminum hydroxide: A mechanistic investigation

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Particuology 2012年第3期10卷 359-364页

作者： Thimmasandra Narayan ramesh Centre for Advanced Materials and Department of Chemistry Tumkur University

The diffusion of ammonia vapors into a solution of aluminum nitrate or ferric nitrate results in the precipitation of their respective hydroxides and oxyhydroxides. Polymorphic phase formation of aluminum hydroxide is controlled by the rate of crystallization. The PXRD patterns of products obtained via vapor phase diffusion revealed that poorly ordered aluminum hydroxide is formed during the initial stages of crystallization. After 8 days, the formation of the bayerite phase of aluminum hydroxide was observed. Upon prolonged exposure to ammonia vapors, bayerite was transformed into gibbsite. The infrared spectrum of the product confirmed the presence of different polytypic phases of aluminum hydroxide. The results demonstrated that the crystal structure of metal hydroxides is controlled by the rate of crystallization, nature of the metal ion, site selectivity and specificity and preparative conditions.

关键词： Vapor phase diffusionAluminum hydroxidegibbsiteBayeritePolytypism

Simultaneous effects of MHD and Joule heating on the fundamental flows of a Casson liquid with slip

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Propulsion and Power Research 2021年第2期10卷 118-129页

作者： k.ramesh Arshad Riaz Zahoor Ahmad Dar Department of Mathematics Symbiosis Institute of TechnologySymbiosis International(Deemed University)Pune412115India Department of Mathematics Division of Science and TechnologyUniversity of EducationLahore54770Pakistan Department of Mathematics Lovely Professional UniversityJalandhar144411India

Magnetic field plays a significant role in innumerable fields like mechanical,chemical,biological and medical *** examples include power generation systems,magnetohydrodynamic(MHD)accelerators,liquid metal fluids,cooling of nuclear reactors,hightemperature plasmas,chemical processing equipment and electronic *** view of these facts,the current investigation discusses the fundamental flows of a Casson fluid in horizontal parallel plates(three fundamental situations considered such as the plate walls progresses in the conflicting directions,the progress of lower plate in the flow direction and other is in fixed position,and the progress of the plates in the flow direction respectively).Influences of radiation,velocity slip,porous medium and Joule heating are considered into *** flow situation is assumed in Cartesian coordinate *** momentum and energy equations are transformed into non-dimensional system utilizing appropriate nondimensional *** exact solutions of the non-dimensional differential equations have been *** pictorial representations are provided for the velocity as well as temperature characteristics in all the mentioned *** is concluded by graphical approach that velocity is enhanced in the case of increasing Darcy’s parameter and boundary slip while reduced for the large magnetic *** the other hand,it is found that slip factor is reducing the heat transfer rate while magnetic field is giving rise to it.

关键词： Casson fluid Viscous dissipation Joule heating Porous medium Thermal radiation Magnetofluiddynamics

Late Cenozoic seismic stratigraphy of the Andaman Forearc Basin,Indian Ocean

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Petroleum Science 2017年第4期14卷 648-661页

作者： Dhananjai k.Pandey goli Anitha ramesh Prerna Anju Pandey ESSO-National Centre for Antarctic and Ocean Research Headland SadaVasco da GamaGoa 403 804India

Interpretation of new multichannel seismic reflection data from the Andaman Forearc Basin(AFB) in the northern Indian Ocean is presented here. The highquality multichannel seismic data from the Andaman Forearc region enable us to examine the seismic characters and to demarcate seismic sequences bounded by distinct unconformities. Ages of marked seismic horizons have been calibrated with available litholog data from nearby industry boreholes. Seismic interpretation of new data shows that the AFB is filled with * 4.5-s-two way travel time(TWT) thick Neogene to Recent sediments. The entire basin assemblage exhibits two distinct major sequences pertaining to the Neogene and Quaternary times. A large part of the basin is filled with intermittent mass transport deposits(MTD). We infer that the episodic uplift of the Invisible Bank, protuberance of the outerarc and regular deformation through reactivation of preexisting normal faults since the Pleistocene could be attributed as causal mechanisms for the MTDs. Strong bottom simulating reflectors are identified in the Late Miocene and younger sediments of the outerarc and AFB at a depth of * 0.6 s TWT and correspond to the presence of gas hydrates in this region. Our interpretations have significant implications for geodynamic as well as resource exploration in the AFB.

关键词： Andaman Forearc Basin Neogene Uplift Invisible Bank Outerarc Stratigraphy

Surface Waviness in grinding of Thin Mould Insert Using Chilled Air as Coolant

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厦门大学学报（自然科学版） 2002年第S1期41卷 105-106页

作者： Yeo S H k ramesh School of MPE Nanyang Technological UniversityGintic Institute of Manufacturing Technology Singapore Singapore

On going trend of miniaturization in electronic rel at ed parts, which is an average of two times in every 5～7 years introduce grindin g challenges. In grinding process, the surface waviness control of thin parts is an ardent task due to its warpage, induced by the high specific grinding energy (2～10 J/mm 3). Therefore, coolant is often used to avoid thermal damage, obtai n better surface integrity and to prolong wheel life. However coolant, the incomp ressibility media introduce high forces at the grinding zone creating dimensiona l as well as shape instability. In view of these situations chilled air was ap plied in place of conventional coolant. The chilled air is produced using a two -stage vapor compression refrigeration cycle with characteristics of: temperatu re -35 ℃, pressure 0.2～0.3 MPa and flow rate 0.4 m 3/min. Also traces of eco - oil mist that encompass the chilled air are supplied to the grinding zone. B oth chilled air and eco-oil mist are applied through two independent paths of a specially designed twin compartment nozzle for maximizing the penetration. This paper investigates the grinding characteristics of mold insert which is closer to M2 tool steel (component widely used in connector industries) when using chil led air as coolant media. grinding experiments were conducted using a vitrified bond CBN wheel (B91N100V) and a surface grinder. Initial study was focussed on establishing the most suita ble clamping method for the thin mold insert. FEM analysis and grinding experime nt studies were performed to quantitatively analyze the clamping induced deflect ion. Waviness value (W t) of (24～62) μm was achieved for resin clampi n g whereas (4～8) μm, (4～6) μm were achieved for magnetic and wax clamping res pe ctively. Wax clamping is predominantly used in all the grinding experiments that characterize the grinding process, which use chilled air as the coolant media. Between 0.15 to 0.9 mm 3/mm.s of specific material removal rate, ground sur face tempe

关键词： In Surface Waviness in grinding of Thin Mould Insert Using Chilled Air as Coolant

Maximum Power Enhancement Under Partial Shadings Using a Modified Sudoku Reconfiguration

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CSEE Journal of Power and Energy Systems 2021年第6期7卷 1187-1201页

作者： kandipati Rajani Tejavathu ramesh the Electrical Engineering Department National Institute of Technology Andhra PradeshWest Godavari-534101India

Partial shading is one of the important factors in reducing maximum power generation from PV(Photovoltaic)*** power generation can be improved by selecting a PV array through a Total-Cross-Tied(T-C-T)***,maximum power generated from T-C-T can still be improved by distribution of shading over various *** to distribution of shading,the current entering the node increases and results in improved maximum power *** can be done effectively by using Sudoku reconfiguration *** techniques are economical,since they don’t require any sensors and switching *** technique only changes the physical location of the PV panel but the electrical connection between the panels remains the *** paper proposes a Modified Sudoku reconfiguration pattern which enhances the maximum power from the T-C-T connected PV ***,the theoretical calculation of row current and power output have been done for existing and proposed topologies under various shading *** performance of the proposed pattern has been analyzed and compared using specifications,such as global Maximum Power(gMP),Fill Factor(FF),mismatch losses,and *** the results,it can be concluded that the Modified Sudoku reconfiguration enhances the gMP under all shading conditions.

关键词： Efficiency fill factor global maximum power point mismatch losses partial shadings PV array reconfiguration shading patterns sudoku and total-cross-tied

Influence of Sputtering gas on Morphological and Optical Properties of Magnesium Films

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Journal of Materials Science & Technology 2011年第1期27卷 51-58页

作者： Yogendra k.gautam Amit k.Chawla Vipin Chawla R.D.Agrawal ramesh Chandra Department of Metallurgical and Materials Engineering Indian Institute of Technology Roorkee Nano Science Laboratory Institute Instrumentation CentreIndian Institute of Technology Roorkee

The influence of sputtering gas（He Ar） on the structural properties of Mg thin films has been *** optical property（reflectance） that results from the growth of films at varying substrate temperatures（Tsub） was also *** deposited films were characterized by using X-ray diffraction（XRD）,field emission scaning electron microscopy（FE-SEM）,atomic force microscopy（AFM） and UV-Vis-NIR *** smaller crystallite size and lower deposition rate were observed in the presence of Helium atmosphere compared to *** of the films shows 2D hexagonal geometry of grains in the deposition temperature range（Tsub≈50-150℃） in both the sputtering *** surface roughness of the polycrystalline films were found to increase with increase in the deposition temperature of both ambient *** reflectance of Mg films was measured in near infrared region and larger reflectance was observed from Mg films sputtered in He atmosphere compared to that in argon.

关键词： X-ray diffraction(XRD) Atomic force microscopy(AFM) Reflectance Mg films Microstructure

Closed-Form Solutions of Stress Intensity Factors for Semi-elliptical Surface Cracks in a Cylindrical Bar Under Pure Tension

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Acta Mechanica Solida Sinica 2022年第2期35卷 344-356页

作者： M.k.Ramezani S.ramesh J.Purbolaksono R.Das Centre of Advanced Manufacturing and Materials Processing Department of Mechanical EngineeringFaculty of EngineeringUniversity of MalayaKuala Lumpur 50603Malaysia Department of Mechanical Engineering University of PertaminaJakarta 12220Indonesia Sir Lawrence Wackett Aerospace Research Centre School of EngineeringRMIT UniversityMelbourneVI 3000Australia

In this work,the stress intensity factors(SIFs)for a wide range of semi-elliptical surface cracks with different inclination angles in a cylindrical bar subjected to pure tension were investigated *** main parameters considered to evaluate the SIFs were the crack size ratio(a/d),the crack aspect ratio(a/c),and the crack inclination angle(0).The dual-boundary element met hod implemented in software BEASY was used to compute the SIF values for *** her more,the general closed-form solutions were proposed to evaluate the corresponding SIFs for Mode I,Mode II and Mode III types of fracture through curve fitting *** solutions can provide accurate and reliable values of stress intensity factors for a crack on a cylindrical bar under pure tension in a rapid way compared to those obtained using computational *** addition,these results can be used as inputs for failure studies and life evaluations of cracked cylinder under working conditions.

关键词： Stress intensity factor Surface crack Solid cylinder Closed-form solution Dual-boundary element method