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Now showing 1 - 10 of 24
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    Development of noise spectrum based maintenance guideline for reduction of heavy earth moving machinery noise
    (2006) Vardhan, H.; Adhikari, G.R.
    Heavy earth moving machinery (HEMM) is one of the most important sources of noise in open-pit mines. Several studies carried out earlier indicate that noise produced by HEMM can be reduced by proper maintenance. To reduce the overall noise produced by HEMM it is important to identify the components contributing most to the noise. Maintenance of those components can then be carried out rigorously to reduce the noise. This paper presents the development of a maintenance guideline for reduction of HEMM noise based on sound level emissions and noise spectrum studies. The sound level emission and noise spectrum based maintenance guidelines were obtained through noise measurement of HEMM like dumpers, dozers and front-end-loaders over a period of time and under various test conditions. These guidelines can help the maintenance crew for the reduction of noise from HEMM. © 2006 Institute of Noise Control Engineering.
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    Discrete cosine harmonic wavelet transform and its application to signal compression and subband spectral estimation using modified group delay
    (2009) Narasimhan, S.V.; Harish, M.; Haripriya, A.R.; Basumallick, N.
    This paper proposes a new harmonic wavelet transform (HWT) based on discrete cosine transform (DCTHWT) and its application for signal or image compression and subband spectral estimation using modified group delay (MGD). Further, the existing DFTHWT has also been explored for image compression. The DCTHWT provides better quality decomposed decimated signals, which enable improved compression and MGD processing. For signal/image compression, compared to the HWT based on DFT (DFTHWT), the DCTHWT reduces the reconstruction error. Compared to DFTHWT for the speech signal considered for a compression factor of 0.62, the DCTWHT provides a 30% reduction in reconstruction error. For an image, the DCTHWT algorithm due to its real nature, is computationally simple and more accurate than the DFTHWT. Further compared to Cohen-Daubechies-Feauveau 9/7 biorthogonal symmetric wavelet, the DCTHWT, with its computational advantage, gives a better or comparable performance. For an image with 6.25% coefficients, the reconstructed image by DFTHWT is significantly inferior in appearance to that by DCTHWT which is reflected in the error index as its values are 3.0 and 2.65%, respectively. For spectral estimation, DCTHWT reduces the bias both in frequency (frequency resolution) and spectral magnitude. The reduction in magnitude bias in turn improves the signal detectability. In DCTHWT, the improvement in frequency resolution and the signal detectability is not only due to good quality DCT subband signals but also due to their stretching (decimation) in the wavelet transform. The MGD reduces the variance while preserving the frequency resolution achieved by DCT and decimation. In view of these, the new spectral estimator facilitates a significant improvement both in magnitude and frequency bias, variance and signal detection ability; compared to those of MGD processing of both DFT and DCT fullband and DFT subband signals. © Springer-Verlag London Limited 2008.
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    Palladium-Schiff base-triphenylphosphine catalyzed oxidation of alcohols
    (2010) Dileep, R.; Badekai Ramachandra, B.
    Novel palladium(II)-N-(2-pyridyl)-N'-(5-R-salicylidene) hydrazine triphenylphosphine complexes were synthesized and characterized by UV, IR, 1HNMR and31P NMR spectral analysis, C, H, N analysis andmagnetic susceptibilitymeasurements. The complexes were effective in the catalytic oxidation of primary and secondary alcohols in presence of N-methyl-morpholine-Noxide as oxidant. The oxidation reactions were carried out in dichloromethane. A mechanistic study of the above reactions has been proposed. Copyright© 2010 JohnWiley & Sons, Ltd.
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    2D-spectral estimation based on DCT and modified magnitude group delay
    (2013) Sandeep, P.; Shreyamsha Kumar, B.K.; Narasimhan, S.V.
    This paper proposes two new 2D-spectral estimation methods. The 2D-modified magnitude group delay (MMGD) is applied to 2D-discrete Fourier transform (2D-DFT) for the first and to the analytic 2D-discrete Cosine transform for the second. The analytic 2D-DCT preserves the desirable properties of the DCT (like, improved frequency resolution, leakage and detectability) and is realized by a 2D-discrete cosine transform (2D-DCT) and its Hilbert transform. The 2D-MMGD is an extension from 1D to 2D, and it reduces the variance preserving the original frequency resolution of 2D-DFT or 2D-analytic DCT, depending upon to which is applied. The first and the second methods are referred to as DFT-MMGD and DCT-MMGD, respectively. The proposed methods are applied to 2D sinusoids and 2D AR process, associated with Gaussian white noise. The performance of the DCT-MMGD is found to be superior to that of DFT-MMGD in terms of variance, frequency resolution and detectability. The performance of DFT-MMGD and DCT-MMGD is better than that of 2D-LP method even when the signal to noise ratio is low. © 2012 Springer-Verlag London Limited.
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    Polarity dependent photoisomerization of ether substituted azodyes: Synthesis and photoswitching behavior
    (Elsevier, 2015) Gan, S.M.; Pearl, Z.F.; Yuvaraj, A.R.; Lutfor, M.R.; Hegde, H.
    Two new ether substituted azodyes were synthesized and characterized by different spectral analysis such as 1H NMR, 13C NMR, FTIR and UV/Vis. Synthesized compounds were used to study the photoisomerization phenomenon by using UV-Vis spectro-photometer. Interesting polarity dependent effect is observed for the first time on these materials. Trans-cis (E-Z) and cis-trans (Z-E) conversion occurred within 41 s and 445 min, respectively for both the compounds in solutions. Polarizing optical microscopy studies revealed that there is no liquid crystal phase for both the compounds. The dramatic variation in the optical property is speculated to be the polarity of the chemical species. These derivatives are useful to fabricate optical data storage devices. © 2015 Published by Elsevier B.V.
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    NiWO4-ZnO-NRGO ternary nanocomposite as an efficient photocatalyst for degradation of methylene blue and reduction of 4-nitro phenol
    (Elsevier Ltd, 2017) Mohamed, M.; Shenoy, U.S.; Bhat, D.K.
    A novel NiWO4-ZnO-NRGO ternary nanocomposite has been efficiently synthesized by decorating nitrogen doped reduced graphene oxide (NRGO) with zinc oxide and nickel tungstate nanoparticles via a facile microwave irradiation technique and its capability to catalyze photodegradation of methylene blue (MB) dye in aqueous solution and reduction of 4-nitro phenol (4-NP) to 4-amino phenol (4-AP) using sodium borohydride was explored. The as-synthesized nanocomposite was characterized by X-ray diffraction (XRD), Raman spectroscopy, Brunauer-Emmett-Teller (BET) analysis, energy dispersive X-ray (EDX) analysis, field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), photoluminescence (PL) spectroscopy and diffuse reflectance spectroscopy (DRS) techniques. The photocatalytic activity of the as-synthesized nanocomposite estimated through the photodegradation of MB under visible light irradiation showed 9 times improvement over pure NiWO4. It also showed excellent catalytic activity in reduction of 4-NP to 4-AP. The material also showed excellent stability and reusability. The entire study revealed that the novel NiWO4-ZnO-NRGO ternary nanocomposite can act as a promising bifunctional photocatalyst for environmental remediation and industrial application. © 2017 Elsevier Ltd
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    Effect of Zn doping on the structural, optical, photoluminescence and mechanical properties of thiourea barium chloride (TBC) crystal
    (Elsevier Ltd, 2017) Mahendra, K.; D'Souza, A.; Udayashankar, N.K.
    In the present work, a synthesis and comparative study on the effect of Zinc (Zn) on thiourea barium chloride (TBC) single crystals has been reported. Crystals of thiourea barium chloride and Zn-doped thiourea barium chloride crystals are prepared using slow evaporation from the saturated solution. The samples were subjected to single crystal and powder X-ray diffraction to study the unitcell parameters and structural variations. The functional groups present in the crystals are derived using FTIR and Raman analysis. The enhancement of transmittance with the addition of Zn and the variations in the parameters such as bandgap, extinction coefficient, reflectance, refractive index, optical and electrical conductivity, real and imaginary part of dielectric constant are studied from UV–vis spectrum analysis. Vickers hardness measurements are conducted for pure and Zinc-doped TBC single crystals. The emission spectrum of pure and Zn doped single crystals are studied using photoluminescence analysis. © 2017 Elsevier Ltd
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    Improving the catalytic efficiency of Fibrinolytic enzyme from Serratia marcescens subsp. sakuensis by chemical modification
    (Elsevier Ltd, 2018) Krishnamurthy, A.; Mundra, S.; Belur, P.D.
    Microbial fibrinolytic enzymes have gained increased attention due to their potential to prevent or cure cardiovascular diseases. Promising natural enzymes are often modified to improve/enhance the kinetic constants. Hence an attempt was made to chemically modify the fibrinolytic enzyme produced by marine Serratia marcescens subsp. sakuensis using amino acid specific modifiers. The aim was to enhance the kinetic constants and gather information on the vital amino acid residues involved in the catalysis. Modification of cysteine, histidine, tryptophan and serine residues resulted in drastic reduction in fibrinolytic activity indicating their presence in the active site. Modification of carboxylate residues resulted in a 19-fold increase in specific activity suggesting their presence in the catalytic site. Interestingly, ratio of fibrinolytic to fibrinogenolytic activity of the modified enzyme did not change significantly. There was a 507-fold reduction in Km value after chemical modification and due to that, 219-fold enhancement of catalytic efficiency was evidenced. Circular dichroism spectrum analysis of the modified and native enzyme revealed changes in ?- helix and ß-sheet conformation of the enzyme. Furthermore, the modified enzyme was more responsive to the presence of most of the metal ions tested. © 2018 Elsevier Ltd
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    Effects of transformer-oil temperature on amplitude and peak frequency of partial discharge acoustic signals
    (Institute of Electrical and Electronics Engineers Inc., 2018) Shanker, T.B.; Nagamani, H.N.; Antony, D.; Punekar, G.S.
    The behavior of partial discharge (PD) acoustic emission (AE) signals in the transformer oil for a temperature range of 30-75 °C is studied via laboratory experiments. The AE signals are analyzed using the fast Fourier transform (FFT) to obtain the peak frequency and the AE amplitude. A peculiar behavior of reduction in the peak frequency and the AE amplitude observed above 65 °C is reported. An attempt is made to explain the reduction in the AE amplitude after a certain temperature by correlating it with the properties of the transformer oil such as the viscosity and the breakdown voltage. This AE signal analysis is perhaps an important advancement in the PD diagnosis and the PD spectrum analysis at different temperatures in the transformer oil. © 1986-2012 IEEE.