Browsing by Author "Rao, D.S."

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    Assessment of noise induced hearing loss (NIHL) of mine workers in a bauxite mine using fuzzy logic
    (2015) Tripathy, D.P.; Rao, D.S.
    Noise induced hearing loss is a noticeable problem in mining industry and is mainly caused due to constant exposure to noise. Frequent exposures to loud machinery, over a prolonged period of time, present severe risks to human hearing. In surveys conducted by the DGMS/investigators, it was found that noise levels in majority of the mining operations were higher than the recommended limit of 85 dB (A). In this paper, an attempt has been made to conduct audiometry survey of 200 mine workers of a major bauxite mine of Odisha, India. Data of miners exposed to noise (? 85 dB A) were included and tested for noise-induced hearing loss (NIHL) by using Digital Audiometer. Audiometry results showed that 2.3% miners were affected by NIHL in the age group of 38 to 55 years. Further a GUI model was developed to predict NIHL by using noise level, frequency and exposure to noise. GUI model showed that the high level of exposure to noise is directly proportional to percentage of NIHL. � 2015 by ASME.
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    Assessment of noise induced hearing loss (NIHL) of mine workers in a bauxite mine using fuzzy logic
    (The Institute of Noise Control Engineering of the USA, Inc., 2015) Tripathy, D.P.; Rao, D.S.
    Noise induced hearing loss is a noticeable problem in mining industry and is mainly caused due to constant exposure to noise. Frequent exposures to loud machinery, over a prolonged period of time, present severe risks to human hearing. In surveys conducted by the DGMS/investigators, it was found that noise levels in majority of the mining operations were higher than the recommended limit of 85 dB (A). In this paper, an attempt has been made to conduct audiometry survey of 200 mine workers of a major bauxite mine of Odisha, India. Data of miners exposed to noise (≥ 85 dB A) were included and tested for noise-induced hearing loss (NIHL) by using Digital Audiometer. Audiometry results showed that 2.3% miners were affected by NIHL in the age group of 38 to 55 years. Further a GUI model was developed to predict NIHL by using noise level, frequency and exposure to noise. GUI model showed that the high level of exposure to noise is directly proportional to percentage of NIHL. © 2015 by ASME.
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    Comparative hot corrosion performance of APS and Detonation sprayed CoCrAlY, NiCoCrAlY and NiCr coatings on T91 boiler steel
    (Elsevier Ltd, 2021) Sundaresan, C.; Rajasekaran, B.; Varalakshmi, S.; Santhy, K.; Rao, D.S.; Govindarajan, G.
    Hot corrosion performance of Atmospheric Plasma Spray (APS) and Detonation spray (DSC) CoCrAlY, NiCoCrAlY, and NiCr coatings on T91 steel were investigated at 650 °C for 100 cycles under Na2SO4-K2SO4-Fe2O3 mixed salt deposit in ambient air. The hot corrosion resistance of DSC coatings was found to be superior to their APS counterparts. Chromia and spinel oxides provided excellent corrosion resistance while no ?-Al2O3 was observed. DSC NiCr and APS NiCoCrAlY offered the most and the least corrosion resistance, respectively. DFT calculation was performed to validate the thermodynamic stability of each oxide and identify the precise oxide formation. © 2021 Elsevier Ltd
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    Hot corrosion behaviour of plasma and d-gun sprayed coatings on t91 steel used in boiler applications
    (Institute of Physics Publishing helen.craven@iop.org, 2020) Sundaresan, C.; Rajasekaran, B.; Govindarajan, G.; Rao, D.S.
    Material degradation by salt induced hot corrosion is a serious threat to Coal fired Boiler components. Corrosion resistant thermal spray coatings is a proven solution for this problem. Thiswork compares the hot corrosion behaviour of a NiCoCrAlY coating on T91 boiler steel deposited using two different thermal spray methods namely Atmospheric Plasma Spray (APS) and Detonation Gun (D-Gun) spray. The coated samples were exposed to 650C for 100 cycles (1 cycle being 1 hour holding plus 20 minutes cooling in air) in a thermal cycling furnace under a mixed deposit containing Na2SO4, K2SO4 and Fe2O3 to simulate the real time coal ash environment. The exposed coatings were examined using FESEM/EDS and XRD to analyze the extent and nature of corrosion attack. The results indicate that the D-Gun sprayed coatings provided superior corrosion resistance over their APS sprayed counterparts. NiO and Spinel oxide NiCr2O4 which offers corrosion resistance were formed in both the coatingswith the APS sprayed coatingbeing rich in the fast growing NiO which affected its corrosion performance. The enhanced corrosion resistance of the D-Gun sprayed coatings was attributed to its dense microstructure with minimal porosity and good intersplat bonding which minimized corrosion ingress. © Published under licence by IOP Publishing Ltd.
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    Investigations on the effect of ball burnishing parameters on surface hardness and wear resistance of HSLA dual-phase steels
    (2008) Rao, D.S.; Hebbar, H.S.; Komaraiah, M.; Kempaiah, U.N.
    Surface finish has a vital influence on most functional properties of a component like fatigue life, wear resistance, corrosion resistance, etc. This has given birth to processes such as lapping, honing, burnishing, etc. Burnishing is a fine finishing operation involving the cold working plastic deformation of surface layers to enhance the surface integrity and the functional utility of a component. The present study has been carried out to establish the effect of burnishing parameters viz. feed rate, speed, force, ball diameter and lubricant on surface hardness, and wear resistance of HSLA dual-phase steel specimens. The result indicates that burnishing parameters have significant effect on the surface hardness and wear resistance.
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    Noise measurement in a mechanized opencast bauxite mine: A case study
    (Multi-Science Publishing Co. Ltd claims@sagepub.com, 2015) Tripathy, D.P.; Rao, D.S.
    Occupational noise is one of the most common pollutants in the mining sector. Prolonged exposure of miners to high levels of noise can cause noise induced hearing loss besides several non-auditory health effects. As these effects have a significant impact on people's health, it is essential to assess the noise exposure and to adopt ameliorative solutions. This work has been carried out to study the noise levels of different machines in a highly mechanized opencast bauxite mine of Odisha, India. A number of measurements have been carried out using an Extech 1/3 Octave band analyser and sound level meter to collect data where the miners are exposed to different tasks during the occupational process. Noise measurements were carried out at work places of 10 different machinery sources in the bauxite mine. The average noise levels generated from the different machines were compared with permissible exposure levels of workers as per OSHA guidelines. Further contour mapping was plotted to show the noise levels at each work place.
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    Studies on the effect of ball burnishing parameters on surface hardness of HSLA dual-phase steels using factorial design
    (2008) Rao, D.S.; Hebbar, H.S.; Komaraiah, M.; Kempaiah, U.N.
    Burnishing is used increasingly as a finishing operation which gives additional advantages such as increased hardness, fatigue strength and wear resistance. Experimental work based on 34 factorial design was carried out to establish the effects of ball burnishing parameters on the surface hardness of HSLA dualphase steel specimens. Statistical analysis of the results shows that the speed, feed, lubricant and ball diameter have significant effect on surface hardness.
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    Studies on the effect of ball burnishing parameters on surface hardness of HSLA dual-phase steels using factorial design
    (Indian Institute of Metals, 2008) Rao, D.S.; Hebbar, H.S.; Komaraiah, M.; Kempaiah, U.N.
    Burnishing is used increasingly as a finishing operation which gives additional advantages such as increased hardness, fatigue strength and wear resistance. Experimental work based on 34 factorial design was carried out to establish the effects of ball burnishing parameters on the surface hardness of HSLA dualphase steel specimens. Statistical analysis of the results shows that the speed, feed, lubricant and ball diameter have significant effect on surface hardness.
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    Surface hardening of high-strength low alloy steels (HSLA) dual-phase steels by ball burnishing using factorial design
    (2007) Rao, D.S.; Hebbar, H.S.; Komaraiah, M.
    Burnishing is used increasingly as a finishing operation which gives additional advantages such as increased hardness, fatigue strength, and wear resistance. Experimental work based on 34 factorial design was carried out to establish the effects of ball burnishing parameters on the surface hardness of high-strength low alloy steels (HSLA) dual-phase (DP) steel specimens. Statistical analysis of the results shows that the speed, feed, lubricant and ball diameter have significant effect on surface hardness.