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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

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

A Novel Process of CO_(2) Reduction and CO_(2) Sequestration Through an Innovative Accelerated Carbonation Technique

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Journal of Wuhan University of Technology(Materials Science) 2023年第5期38卷 1105-1117页

作者： Akshay ramesh Bura B Kondraivendhan Department of Civil Engineering Sardar Vallabhbhai National Institute of TechnologySuratGujaratIndia 395007

The efiect of an innovative accelerated carbonation curing technique was evaluated on concrete containing natural zeolite powder and fine aggregate as partial replacement to alleviate the CO_(2) emission up to a certain extent from the concrete production industry and improve sequestration of CO_(2) into the concrete matrix in a stable *** accelerated carbonation curing was accomplished by subjecting the concrete specimens to 0.5 and 0.75 M concentrations of sodium bicarbonate(NaHCO_(3)) solutions up to a curing age of 180 days after the initial 28 days of normal water *** for carbonation depth,pH value,compressive strength,calcium carbonate(CaCO_(3))content,X-ray difiraction,and thermogravimetric(TGA)analyses and Fourier transform infrared spectroscopy(FTIR)were performed to measure the extent of *** obtained results showed an increment in average compressive strength for the zeolite concrete(ZLC)mixes exposed to accelerated carbonation *** ZLC mixes exposed to increasing NaHCO_(3) solution concentration and exposure period exhibited greater carbonation depth and decreased pH at each depth interval indicating higher CO_(2) sequestration within the concrete *** results obtained from the microstructural analysis(XRD,TGA,and FTIR)and CaCO_(3) content measurements confirm that the higher amount of CaCO_(3) formation provides a clear indication of the carbonation enhancement and CO_(2) sequestration within the concrete matrix and in turn contributing to the global warming reduction.

关键词： CO_(2)sequestration accelerated carbonation natural zeolite calcium carbonate

An assessment on the test setups used for energy labeling of ceiling fans

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Building Simulation 2021年第4期14卷 1175-1188页

作者： Dilshan ramesh Casseer Chathura Ranasinghe Department of Mechanical Engineering University of MoratuwaMoratuwaSri Lanka

Ceiling fans are used all over the world as a mean of enhancing indoor thermal comfort. A number of grading programs have been initiated for assessing energy performance of ceiling fans, such as ANSI/AMCA 230, Energy Star, IEC 60879, IS 374 and SLS 1600. The configurations of test setups used for performance evaluations in these standards have significant differences to each other. In this study, the influence of such differences on the calculated performance grade of ceiling fans were investigated and the suitability of each dimension of the test set-up is discussed. Particular emphasis was placed on quantifying the effect of the cylindrical drum used in Energy Star and SLS test methods. For this assessment, extensive three-dimensional numerical simulations and experimental measurements were used. Accordingly, the effect of cylinder height, gap between the fan rotation plane and the cylinder, cylinder diameter and the dimensions of the test chamber were investigated. Results show that, the test cylinder, has no significant impact on the calculated performance grade of the tested ceiling fan (variation is less than 2%), and may be eliminated from the test setup. This justifies the recent decision of AMCA on the removal of test cylinder from the fan test set-up. Further, it was also found that the set up dimensions considered herein is large enough so that the calculated start rating is uneffaced by the surrounding solid walls.

关键词： ceiling fans energy label Energy Star test standards efficiency

Application of HPLC and ESI-MS techniques in the analysis of phenolic acids and flavonoids from green leafy vegetables (GLVs)

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Journal of Pharmaceutical Analysis 2017年第6期7卷 349-364页

作者： ramesh Kumar Bonta Plant Metabolic Pathway Laboratory RGSOIPLIndian Institute of Technology KharagpurKharagpurWest Bengal 721302India

Diets containing high proportions of fruits and vegetables reduce the risk of onset of chronic diseases. The role of herbal medicines in improving human health is gaining popularity over the years, which also increases the need for safety and efficiency of these products. Green leafy vegetables （GLVs） are the richest source of phenolic compounds with excellent antioxidant properties. Increased consumption of diets containing phenolic compounds may give positive and better results to human health and significantly improves the immune system. Highly selective, susceptible and versatile analytical techniques are necessary for extraction, identifica- tion, and quantification of phenolic compounds from plant extracts, which helps to utilize their important biological properties. Recent advances in the pre-treatment procedures, separation techniques and spectro- metry methods are used for qualitative and quantitative analysis of phenolic compounds. The online coupling of liquid chromatography with mass spectrometry （LC-MS） has become a useful tool in the metabolic profiling of plant samples. In this review, the separation and identification of phenolic acids and flavonoids from GLVs by LC-MS have been discussed along with the general extraction procedures and other sources of mass spectrometer used. The review is devoted to the understanding of the structural configuration, nature and accumulation pattern of phenolic acids and flavonoids in plants and to highlighting the recent developments in the chemical investigation of these compounds by chromatographic and spectroscopic techniques. It concludes with the advantages of the combination of these two methods and prospects.

关键词： Green leafy vegetables Phenolic acids Flavonoids HPLC ESI-MS

Energy Spectra of the Coulomb Perturbed Potential in N-Dimensional Hilbert Space

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Chinese Physics Letters 2012年第6期29卷 35-38页

作者： ramesh Kumar Fakir Chand Department of Physics Kurukshetra UniversityKurukshetra-136119India

We deal with the solutions to the radial Schr(o)dinger equation for the Coulomb perturbed potential in Ndimensional Hilbert space by using two methods,*** power series technique via a suitable ansatz to the wavefunction and the Virial *** expressions for eigenvalues and normalized eigenfunctions are derived.A recursion relation among series expansion coefficients,a condition for convergence of series and interdimensional degeneracies are also *** special cases,the problem is solved in 3 and 4 dimensions with some specific parameter *** obtained analytical and numerical results are in good agreement with the results of other studies.

关键词： dimensions normalized perturbed

Detailed parametric design methodology for hydrodynamics of liquid-solid circulating fluidized bed using design of experiments

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Particuology 2017年第2期15卷 59-68页

作者： Ritesh ramesh Palkar Vidyasagar Shilapuram Chemical Engineering Department National Institute of Technology Warangal 506004 Telangana India

A design-of-experiments methodology is used to develop a statistical model for the prediction of the hydrodynamics of a liquid–solid circulating fluidized bed. To illustrate the multilevel factorial design approach, a step by step methodology is taken to study the effects of the interactions among the independent factors considered on the performance variables. A multilevel full factorial design with three levels of the two factors and five levels of the third factor has been studied. Various statistical models such as the linear, two-factor interaction, quadratic, and cubic models are tested. The model has been developed to predict responses, viz., average solids holdup and solids circulation rate. The validity of the developed regression model is verified using the analysis of variance. Furthermore, the model developed was compared with an experimental dataset to assess its adequacy and reliability. This detailed statistical design methodology for non-linear systems considered here provides a very important tool for design and optimization in a cost-effective approach

关键词： Hydrodynamics Liquid-solid circulating fluidized bed Statistical design Factorial design approach Response prediction Analysis of variance

Experimental Investigation for NO_x Emission Reduction in Hydrogen Fueled Spark Ignition Engine Using Spark Timing Retardation, Exhaust Gas Recirculation and Water Injection Techniques

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Journal of Thermal Science 2019年第4期28卷 789-800页

作者： JEERAGAL ramesh K.A.Subramanian Engines and Unconventional Fuels Laboratory Centre for Energy Studies IIT Delhi

The experimental tests were carried out on a single cylinder hydrogen fueled spark ignition(SI)generator set with different spark timings(4-20℃A bTDC),exhaust gas recirculation(EGR)up to 28% by volume and water injection up to 1.95 kg/h(maximum water to fuel mass ratio of 8:1).The engine speed was kept constant of 3000 r/*** NOx emission and thermal efficiency of engine with gasoline and hydrogen fuel operation at 1.4 kW power output are 5 g/kWh and 12.1 g/kWh,and 15% and 20.9% *** order to reduce the NOx emission at source level,retarding spark timing,exhaust gas recirculation(EGR),and water injection techniques were *** emission decreased with spark timing retardation,EGR,and water *** emission with hydrogen at 1.4 kW power output decreased from 12.1 g/kWh with maximum brake torque(MBT)spark timing(10℃A bTDC)to 8.1 g/kWh with retarded spark timing(4℃A bTDC)due to decrease in the in-cylinder peak pressure and *** Nox emission decreased to 6.1 g/kWh with 20% EGR due to thermal and chemical dilution ***,thermal efficiency decreased about 33% and 17% with spark timing retardation and 20EGR respectively as compared to that of MBT spark ***,in the case of water injection,the NOx emission decreased significantly without affecting the thermal efficiency of the engine and it is 5.6 g/kWh with water-hydrogen ratio of 4:1(water flow rate of 0.92 kg/h).Water injection is the best suitable method to reduce the NOx emission in a hydrogen fueled engine compared with the spark timing retardation and EGR technique.

关键词： hydrogen spark ignition engine spark timing exhaust gas recirculation NOx emission water injection

Why is graphene an extraordinary material? A review based on a decade of research

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Frontiers of Materials Science 2022年第2期16卷 1-39页

作者： Sachin Sharma Ashok KUMAR Shahid BASHIR Kasi ramesh Subramaniam ramesh Centre for Ionics University of Malaya Department of PhysicsFaculty of ScienceUniversiti MalayaKuala Lumpur 50603Malaysia Higher Institution Centre of Excellence(HICoE) UM Power Energy Dedicated Advanced Centre(UMPEDAC)Level 4Wisma R&DUniversiti MalayaJalan Pantai BaharuKuala Lumpur 59990Malaysia

During this decade,graphene which is a thin layer of carbon material along at ease with synthesis and functionalization has become a hot topic of research owing to excellent mechanical strength,very good current density,high thermal conductivity,superior electrical conductivity,large surface area,and good electron *** research on graphene has exponentially accelerated specially when Geim and Novoselov developed and analyzed *** this basis,for industrial application,researchers are exploring different techniques to produce high-quality ***,reviewed in this article is a brief introduction to graphene and its derivatives along with some of the methods developed to synthesize graphene and its prospective applications in both research and *** this work,recent advances on applications of graphene in various fields such as sensors,energy storage,energy harvesting,high-speed optoelectronics,supercapacitors,touch-based flexible screens,and organic light emitting diode displays have been summarized.

关键词： graphene graphene oxide electrochemical sensor fuel cell supercapacitor dye-sensitized fuel cell lithium battery energy storage