Faculty Publications
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Item Characterization and process optimization of microwave drying of plaster of Paris(2008) Ganesapillai, M.G.; Iyyaswami, I.; Murugesan, T.The changes in the characteristics of plaster of Paris (pop) during drying operation under microwave irradiation conditions, namely surface morphology, effective moisture diffusivity, and absorption of microwave, were studied. The drying characteristics and kinetics of the process during microwave drying of plaster were studied for rectangular-faced cuboids (80 × 70 × 15, L × B × H in mm) through various drying parameters like microwave power input, initial moisture content, and drying time. Further, the experimental data on moisture ratio of plaster for different operating conditions were obtained and the optimization of the microwave drying process parameters was performed with response surface methodology (RSM) by considering all the above-said independent variables. Based on the RSM analysis, the optimum values of the process variables were obtained as: initial moisture content (A) 60%; microwave power input (B) 180 W; and drying time (C) 480 S.Item Hydrogen Sulfide Removal in Biofilter: Evaluation of a new filter material by immobilization of thiobacillus sp(Walter de Gruyter GmbH peter.golla@degruyter.com, 2009) Potumarthi, R.; Anupoju, G.R.; Mugeraya, G.; Jetty, A.Different agricultural residue was evaluated as a biofilter material for the removal of Hydrogen sulfide (H2S) using Thiobacillus sp. A Combination of four different agricultural residues, viz., sugarcane bagasse, coconut coir pith, rice husk and saw dust were evaluated as biofilter material. From results, it was observed that filter material having composition of 2:4:2:2, 4:4:2:2 and 4:2:2:4 has resulted in retaining 70% moisture content at the end of 10 days. The biofilter was operated for 128 days in three phases by varying inlet H2S concentration from 321 to 2020 ppmv. Biofilter exhibited 100% removal efficiency (RE) at an inlet concentration of 570 ppmv, 99% RE at an inlet concentration of 1416 ppmv and 66% RE at a maximum inlet concentration of 2020 ppmv. The filter performance in terms of RE, dropped to 48% when the air was not humidified before sending to the filter, which has direct relation with the MC of the filter material. The RE recovered to 66% with recovery of moisture content (MC) to 57% upon subsequent re-introduction of the humidifier in to the circuit. The pH has dropped from 7.8 to 4.8 during the course of operation of the filter. H2S was effectively removed under different operating conditions using mixed agricultural residue as filter material. However humidification was most essential to maintain the required moisture content in the biofilter. SEM analysis has shown the good growth of Thiobacillus sp. in the filter bed and hence the new material proved to be good support for the immobilization of Thiobacillus sp. Copyright © 2009 The Berkeley Electronic Press. All rights reserved.Item Effect of soil parameters on dynamic cone penetration indices of laterite sub-grade soils from India(2009) George, V.; Nageshwar Rao, Ch.; Shivashankar, R.The focus of this study was on correlating the effect of grain-size, maximum dry-density (MDD), field moisture content, and the void ratios on penetration measured using the dynamic cone penetrometer (DCP) for laterite soils blended with fines. Tests were performed on soil samples compacted to MDD for moulding water contents set to the optimum moisture content (OMC), dry of OMC, and wet of OMC un-soaked condition. The results indicated that an increase in the fines-content caused a decrease in the MDD, and an increase in the OMC and the DCP penetration. Regressions were developed correlating various parameters. © Springer Science+Business Media B.V. 2008.Item Analysis of observed soil moisture patterns under different land covers in Western Ghats, India(2011) Venkatesh, B.; Lakshman, N.; Purandara, B.K.; Reddy, V.B.An understanding of the soil moisture variability is necessary to characterize the linkages between a region's hydrology, ecology and physiography. In the changing land use scenario of Western Ghats, India, where deforestation along with extensive afforestation with exotic species is being undertaken, there is an urgent need to evaluate the impacts of these changes on regional hydrology. The objectives of the present study were: (a) to understand spatio-temporal variability of soil water potential and soil moisture content under different land covers in the humid tropical Western Ghats region and (b) to evaluate differences if any in spatial and temporal patterns of soil moisture content as influenced by nature of land cover. To this end, experimental watersheds located in the Western Ghats of Uttara Kannada District, Karnataka State, India, were established for monitoring of soil moisture. These watersheds possessed homogenous land covers of acacia plantation, natural forest and degraded forest. In addition to the measurements of hydro-meteorological parameters, soil matric potential measurements were made at four locations in each watershed at 50 cm, 100 cm and 150 cm depths at weekly time intervals during the period October 2004-December 2008.Soil moisture contents derived from potential measurements collected were analyzed to characterize the spatial and temporal variations across the three land covers. The results of ANOVA (p<0.01, LSD) test indicated that there was no significant change in the mean soil moisture across land covers. However, significant differences in soil moisture with depth were observed under forested watershed, whereas no such changes with depth were noticed under acacia and degraded land covers. Also, relationships between soil moisture at different depths were evaluated using correlation analysis and multiple linear regression models for prediction of soil moisture from climatic variables and antecedent moisture condition were developed and tested. A regression model relating near-surface soil moisture (50 cm) with profile soil moisture content was developed which may prove useful when surface soil moisture contents derived from satellite remote sensing are available. Overall results of this study indicate that while the nature of land cover has an influence on the spatio-temporal variability of soil moisture, other variables related to topography may have a more dominant effect. © 2010 Elsevier B.V.Item Effects of soil parameters and moisture content on stiffness of unsaturated blended laterite using tri-axial tests for rural roads(2011) George, V.; Nageshwar Rao, C.; Shivashankar, R.Evaluation of subgrade strength and stiffness is essential in the design of pavements and construction of embankments for highways in order to ensure that roads perform their functions satisfactorily over a longer period. The grain size distribution and compaction moisture-content have an immense influence on the strength and stiffness of subgrades. Among the various laboratory tests for evaluation of shear strength parameters, and the modulus of elasticity of subgrades, the tri-axial test plays a major role in describing the geotechnical characteristics of the subgrade. This paper deals with an experimental investigation on unsaturated laterite soils blended with varying percentages of fines. It focuses on a study of the influence of various soil parameters on the stiffness and strength of soil samples compacted at optimum moisture content (OMC), at the drier side of OMC, and also at the wetter side of OMC, and the development of meaningful correlations. © 2011 CAFET-INNOVA TECHNICAL SOCIETY.Item Design and Development of Single & Dual Resonant Frequency Antennas for Moisture Content Measurement(Springer, 2020) Kumar, P.; Chaturvedi, A.The microstrip antenna is designed for the measurement of soil moisture content for agriculture applications. In this paper, the single and dual-band microstrip antennas are designed, simulated and fabricated. The simulated results are compared and analysed with measured results for both designed for different types of feeds. It is found that the simulated and measured results are similar and better. Therefore, the fabricated antennas can be used for the soil moisture content measurement for agriculture applications. The dual resonant frequency antennas results are better than the single band antenna, it covers wide band thus, and it can be applied for wide applications. © 2020, Springer Science+Business Media, LLC, part of Springer Nature.Item Strength and Durability Characteristics of Cement and Class F Fly Ash-Treated Black Cotton Soil(Springer, 2021) Chethan, B.A.; Ravi Shankar, A.U.This paper analyses improvement of the strength and durability characteristics of black cotton (BC) soil treated with cement and Class F fly ash for pavements. The increase in cement dosage (3–14%) improved the UCS, but the specimens could not resist WD durability cycles. In order to improve, industrial by-product Class F fly ash was used in addition to the cement. Different combinations of cement (10, 12, and 14%) and fly ash (10, 15, 20, 25, and 30%) replacements were evaluated for strength and durability characteristics. The higher dosage of fly ash reduced the plasticity with uniform distribution of cement cluster formations, leading to higher UCS. The soil mixes with (cement + fly ash) stabilizer combinations (10 + 30), (12 + 30), (14 + 25), (14 + 30) were stable against WD test with soil loss < 14%. Mix with (14 + 25) stabilizer showed a maximum retained UCS of 3.6 MPa at 2.9% moisture content (MC) after 12 WD cycles. However, most of the mixes showed high resistance to the FT test. The retained UCS of FT tested specimens was more due to low variations in moisture content. Mix with (14 + 30) stabilizer showed a maximum retained UCS of 2.6 MPa at 23.3% MC after 12 FT cycles. The soil samples with high cement and fly ash contents, with 90 days curing, can exhibit significant strength and more resistance to WD and FT cycles with soil loss < 14%. After drying, severe damage to WD specimens was observed due to the drastic absorption of water during the wetting cycle. Durable samples showed good plunger penetration resistance with an expansion of < 2%. Scanning electron microscopy (SEM) images showed the formations of cemented interclusters. CSH formed resulted in strength improvement, as observed from XRD patterns. The 7 days cured WD specimens did not exhibit any volume expansion on soaking, thawing in water. A maximum volumetric shrinkage of 3.2% on drying and 1.91% on freezing was observed for stabilized soil. Hence, the stronger and durable stabilized soil mixes with high volume stability can be used for pavements. © 2021, Indian Geotechnical Society.Item Evaluation of a new vibrating screen for dry screening fine coal with different moisture contents(Routledge, 2022) Shanmugam, B.K.; Vardhan, H.; Raj, M.G.; Kaza, M.; Sah, R.; Hanumanthappa, H.A new vibrating screen was developed with a circular mode of vibration for dry screening of moist coal of size fraction ?3 + 1 mm. Screen mesh of 2 mm aperture size will be used to separate the finer coal particles of size fraction ?2 + 1 mm. The new vibrating screen has the flexibility in changing the operational parameters such as the angle of the screen in upward or downward sloping direction and frequency of vibration of the screen deck. The circular mode of vibration provided to the screen deck will incorporate the inertial force on the particle in the screen deck, reducing screen clogging. The present study involves the analysis of the screening performance of the new vibrating screen with the coal feed of varying moisture content of 4%, 6% and 8%. The maximum screening efficiencies obtained for screening the coal feed with the moisture contents of 4%, 6% and 8% were 85.96%, 77.84%, and 68.27%, respectively. The higher screening performance of new vibrating screen was obtained due to good exposure time, particle mixing, particle segregation and particle stratification of coal on the screen deck. The results of the new vibrating screen will be a breakthrough in dry screening technology and accelerate the pilot-scale development. © 2019 Taylor & Francis Group, LLC.Item Experimentation and statistical prediction of screening performance of coal with different moisture content in the vibrating screen(Routledge, 2022) Shanmugam, B.K.; Vardhan, H.; Raj, M.G.; Kaza, M.; Sah, R.; Hanumanthappa, H.Screening of coal is one of the processes carried out to produce clean coal suitable for the blast furnace. In this work, the screening of moist coal was carried out for different angles of the screen and frequencies. A 2 mm screen perforation was used to separate undersize coal of size +1 mm-2 mm from the +1 mm-3 mm coal samples. For each experimental condition, the screening efficiency was calculated. Maximum screening efficiency of 85.96%, 75.64%, and 63.46% was obtained at 4%, 6%, and 8% moisture content, respectively. As the moisture content of coal increases, the efficiency minimizes due to high screen clogging. After determining the screening efficiency, prediction was carried out using regression modeling. In this work, linear and second-order polynomial regression modeling was utilized to develop a prediction model for the experimental values. From the results, it was clear that the polynomial regression model has high regression coefficient (R2) percentage and low P-value in comparison with the linear regression model. After prediction, validation was carried out on the best fit model. The value of Variance Account For (VAF), Root Mean Square Error (RMSE), and Mean Absolute Percentage Error (MAPE) was in the acceptable range, which shows that the developed model was most effective. © 2020 Taylor & Francis Group, LLC.Item Application of fractional factorial design for evaluating the separation performance of the screening machine(Taylor and Francis Ltd., 2022) Shanmugam, B.K.; Vardhan, H.; Raj, M.G.; Kaza, M.; Sah, R.; Hanumanthappa, H.Implementing the planned execution of experiments will optimize the resources and time of a newly developed process or equipment. In the present work, the screening machine is newly developed equipment designed for the separation of coal. The present work was carried out to evaluate the performance of separation efficiency of the screening machine using generalized and forward selection fractional factorial experimental design. Further, the present work will also determine the significance of each operational variable, such as moisture content, angle, and frequency, for increasing separation efficiency. A cube plot was developed from the experimental design, which shows the highest and lowest condition of separation efficiency for each level of the operational variables. Further, a Pareto chart was developed to evaluate the significant operational variable for the screening machine. The results of the generalized method and forward selection method of fractional design show that the moisture content was the most significant operational variable, followed by angle and frequency. The results also show that the screen blinding of a screening machine plays an important role in reducing the separation efficiency of a screening machine. © 2021 Taylor & Francis Group, LLC.