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B. Subramanian,V. Swaminathan,M. Jayachandran 한국물리학회 2011 Current Applied Physics Vol.11 No.1
The materials properties of nanostructured Aluminum nitride (AlN) film were studied. AlN films of about 2 μm thick were deposited on Si (100) and glass substrates by means of direct current reactive magnetron sputtering in an Ar + N_2 gas mixture. A hexagonal wurtzite structure with a predominant peak was observed along the (002) plane from XRD analysis. Photoelectron peaks from Al, N, O, C and Ar are detected on the surface of the film. Microstructure and topography were analyzed by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The images showed the presence of continuously covered pebble like spherical grains on the surface. AlN films are transparent in the visible region with an average transmittance of 60%. The optical absorption studies give direct band gap equal to 5.2 eV.
B. Subramanian,V. Swaminathan,M. Jayachandran 대한금속·재료학회 2012 METALS AND MATERIALS International Vol.18 No.6
Thin films of Zirconium Nitride (ZrN) were deposited by DC magnetron sputtering. The structure of the films was examined by X-ray diffraction and the crystallographic parameters were refined by Rietveld analysis. The columnar micro-structure was observed via cross-sectional SEM analysis. Defect induced,first order spectra were observed from Laser Raman studies. XPS showed the presence of Zr (N,O) ZrO2phases on the surface of the film. The pitting corrosion was substantially reduced by the employment of Zr film as an interlayer. Corrosion tests revealed that ZrN films with a Zr interlayer exhibited clear passivation characteristics with considerably better corrosion resistance than the film without an interlayer.
B. Subramanian,S. Mohan,Sobha Jayakrishnan,M. Jayachandran 한국물리학회 2007 Current Applied Physics Vol.7 No.3
X-ray diraction analysis showed a preferential orientation along (11) for both sputter deposited and brush plated Ni nanostructurecoatings. The sputtered Ni lm showed better crystallinity as observed from XRD compared to brush plated Ni lm on steel on accountof the favorable conditions for grain growth in sputtering. SEM analysis indicated that the coatings are very regular without pores, withcolumnar structure for the sputter deposited Ni coatings. AFM was also applied for surface topography examination. Microhardnesselectrochemical techniques and observed that the corrosion resistance of brush plated Ni lm sample was signicantly higher than thatof the sputtered Ni film.
Subramanian, Esakkiappan,Baeg, Jin-Ook,Kale, Bharat B.,Lee, Sang-Mi,Moon, Sang-Jin,Kong, Ki-Jeong Korean Chemical Society 2007 Bulletin of the Korean Chemical Society Vol.28 No.11
Tantalum-containing metal oxides, well known for their efficiency in water splitting and H2 production, have never been used in visible light driven photodecomposition of H2S and H2 production. The present work is an attempt in this direction and investigates their efficiency. A mixed metal oxide, ZnFe2Ta2O9, with the inclusion of Fe2O3 to impart color, was prepared by the conventional ceramic route in single- and double-calcinations (represented as ZnFe2Ta2O9-SC and ZnFe2Ta2O9-DC respectively). The XRD characterization shows that both have identical patterns and reveals tetragonal structure to a major extent and a minor contribution of orthorhombic crystalline system. The UV-visible diffuse reflection spectra demonstrate the intense, coherent and wide absorption of visible light by both the catalysts, with absorption edge at 650 nm, giving rise to a band gap of 1.9 eV. Between the two catalysts, however, ZnFe2Ta2O9-DC has greater absorption in almost the entire wavelength region, which accounts for its strong brown coloration than ZnFe2Ta2O9-SC when viewed by the naked eye. In photocatalysis, both catalysts decompose H2S under visible light irradiation (λ ≥ 420 nm) and produce solar H2 at a much higher rate than previously reported catalysts. Nevertheless, ZnFe2Ta2O9-DC distinguishes itself from ZnFe2Ta2O9-SC by exhibiting a higher efficiency because of its greater light absorption. Altogether, the tantalum-containing mixed metal oxide proves its efficient catalytic role in H2S decomposition and H2 production process also.
P. Subramanian,K.B. Dakshayani 한국식품영양과학회 2006 Journal of medicinal food Vol.9 No.1
The effect of .-ketoglutarate (.-KG) on circadian patterns of lipid peroxides and antioxidants in N-nitrosodi-ethylamine (NDEA)-induced hepatocarcinogenesis in rats has been studied. The circadian rhythm characteristics (acrophase,amplitude, and mesor) of thiobarbituric acid-reactive substances (TBARS), antioxidants, superoxide dismutase, catalase, glu-tathione peroxidase, and reduced glutathione were markedly altered in NDEA-treated rats. The delays in acrophase observedin NDEA-treated rats were brought back to near normal range by the administration of .-KG. An increase in mesor valuesof TBARS and a decrease in mesor values of antioxidants in NDEA-administered rats were reversed by .-KG administra-tion. It can be concluded that .-KG exerts its chemopreventive effect by restoring antioxidants and their circadian rhythms.
MODEL-BASED ANALYSIS OF THE MECHANICAL SUBSYSTEM OF AN AIR BRAKE SYSTEM
D. B. SONAWANE,K. NARAYAN,V. S. RAO,S. C. SUBRAMANIAN 한국자동차공학회 2011 International journal of automotive technology Vol.12 No.5
Most commercial vehicles such as buses and trucks use an air brake system, often equipped with an S-cam drum brake, to reduce their speed and/or to stop. With a drum brake system, the clearance between the brake shoe/pad and the brake drum may increase because of various reasons such as wearing of the brake shoe and/or brake drum and drum expansion caused by high heat generation during the braking process. Hence, to ensure proper functioning of the brake system, it is essential that the clearance between the brake shoe and the brake drum is monitored. In this paper, we present a mathematical model for the mechanical subsystem of the air brake system that can be used to monitor this clearance. This mathematical model correlates the push rod stroke transients and the brake chamber pressure transients. A kinematic analysis and a dynamic analysis of the mechanical subsystem of the air brake system were performed, and the results are corroborated with experimental data.
Visible Light Driven ZnFe2Ta2O9 Catalyzed Decomposition of H2S for Solar Hydrogen Production
Esakkiappan Subramanian,Jin-Ook Baeg*,Bharat B. Kale,Sang Mi Lee,문상진,Ki-jeong Kong 대한화학회 2007 Bulletin of the Korean Chemical Society Vol.28 No.11
Tantalum-containing metal oxides, well known for their efficiency in water splitting and H2 production, have never been used in visible light driven photodecomposition of H2S and H2 production. The present work is an attempt in this direction and investigates their efficiency. A mixed metal oxide, ZnFe2Ta2O9, with the inclusion of Fe2O3 to impart color, was prepared by the conventional ceramic route in single- and double-calcinations (represented as ZnFe2Ta2O9-SC and ZnFe2Ta2O9-DC respectively). The XRD characterization shows that both have identical patterns and reveals tetragonal structure to a major extent and a minor contribution of orthorhombic crystalline system. The UV-visible diffuse reflection spectra demonstrate the intense, coherent and wide absorption of visible light by both the catalysts, with absorption edge at 650 nm, giving rise to a band gap of 1.9 eV. Between the two catalysts, however, ZnFe2Ta2O9-DC has greater absorption in almost the entire wavelength region, which accounts for its strong brown coloration than ZnFe2Ta2O9-SC when viewed by the naked eye. In photocatalysis, both catalysts decompose H2S under visible light irradiation (l ³ 420 nm) and produce solar H2 at a much higher rate than previously reported catalysts. Nevertheless, ZnFe2Ta2O9-DC distinguishes itself from ZnFe2Ta2O9-SC by exhibiting a higher efficiency because of its greater light absorption. Altogether, the tantalum-containing mixed metal oxide proves its efficient catalytic role in H2S decomposition and H2 production process also.
Sivakumar Subramanian,A. S. Sekhar,B. V. S. S. S. Prasad 대한기계학회 2015 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.29 No.6
Leakage characteristics, influenced by centrifugal and thermal radial growth are determined computationally for a generic rotating labyrinthseal used in the gas turbine secondary air system. Three seal locations, namely, R25, R50 and R75 are represented by means ofvarying the rotor radius mimicking different radial positions of the seal from the shaft axis. The combined influence of seal location andits radial (Centrifugal and thermal) growth on the leakage performance is investigated for a wide-ranging speeds from 1000 to 3000 rad/s,temperatures ranging from 200 to 450 oC and pressure ratios varying from 1.1 to 2.5, for a chosen initial clearance of 500 micron. Acomparison of the effect of rotation and temperature gradient among different rotors shows that the radial growth and leakage flow ratessignificantly vary with the increasing radius.
MODEL-BASED CONTROL OF AN ELECTROPNEUMATIC BRAKE SYSTEM FOR COMMERCIAL VEHICLES
P. KARTHIKEYAN,D. B. SONAWANE,S. C. SUBRAMANIAN 한국자동차공학회 2010 International journal of automotive technology Vol.11 No.4
A properly functioning brake system is critical for ensuring the safe operation of any vehicle on roadways. Commercial vehicles such as trucks, tractors-trailers and buses are equipped with an air brake system that uses compressed air as the energy transmitting medium. This paper presents a model-based control scheme for an electropneumatic brake system for use in commercial vehicles. A mathematical model for an electropneumatic brake system was developed and corroborated with experimental data. A control scheme was developed based on this model and was used to regulate the pressure of air inside the brake chamber according to a desired pressure trajectory. This control scheme was implemented on an experimental test bench, and its performance was studied for various values of the controller parameter. The control scheme was tested for various desired pressure trajectories reflecting actual brake operation.