Journal Articles
Permanent URI for this collectionhttps://idr.nitk.ac.in/handle/123456789/19884
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Item Application of life cycle assessment in municipal solid waste management: A worldwide critical review(Elsevier Ltd, 2019) Khandelwal, H.; Dhar, H.; Thalla, A.K.; Kumar, S.The whopping increase in solid waste generation all over the world calls for the development of waste management strategies for a sustainable environment. By the quantification of environmental impacts, life cycle assessment (LCA) tool can help in answering the call. It evaluates the environmental performance of municipal solid waste management (MSWM) system which helps decision-maker in selecting the best management strategy with minimum impacts on the environment. But, up to what extent the LCA methodology can be applied to MSWM systems? To address this question, the present study analyzed the 153 LCA studies published till date since 2013 all over the world. The present study analyzed the time evolution, geographical distribution, and methodology applied in LCA studies. It summarized the use of the functional unit, LCA model, Life Cycle Impact Assessment (LCIA) method, MSWM options, and the critical findings of the selected LCAs, along with MSW composition, income group, and the gaps in the application of the studies. For evaluating the dependence of publication of studies and country's economic condition, the countries in which LCA studies were conducted are classified into four groups on the basis of income level viz., lower income, lower middle income, upper middle income, and higher income countries. In terms of technological coverage, 1 ton of MSW was the most used functional unit. SimaPro was the majorly used LCA model while 56 of the total studies didn't mention about the use of LCA model, only 66 of the total studies included sensitivity analysis in the assessment. Integrated solid waste management was found to be the most preferred waste management option. Also, a very limited number of studies have included life cycle costing and social aspects of MSWM system. The results indicated that the majority of the LCA studies are based in Europe and Asia. Shockingly, 178 out of the total countries in the world have not published a single LCA study on MSWM since 2013. Also, it was found that the effect of increasing Gross Domestic Product (GDP) on the publication of LCA studies is irrelevant, possible reasons being the lack of data, time and economic constraints. Establishment of environment-friendly policies and initiatives by the Government along with the participation of public, non-government and private organizations through training courses and seminars might help in improving the LCA applicability in the field of MSWM. © 2018 Elsevier LtdItem Critical review of ribbed solar air heater and performance evaluation of various V-rib configuration(Elsevier Ltd, 2021) Nidhul, K.; Yadav, A.K.; Anish, S.; Kumar, S.The low heat transfer rate in a flat plate solar air heater (SAH) is due to the development of a laminar sub-layer near the heated absorber plate. Owing to this, the plate temperature rises substantially, instigating losses and thus reducing the efficiency. Extensive research has been carried out to mitigate this problem, of which passive technique emerged to be a promising solution. The passive method involves the application of fins/turbulators/ribs on the surface where the boundary layer develops so that it breaks the same. Various profiles and configurations of the ribs ranging from transverse to inclined and continuous to discrete have been presented concisely. Correlations on Nusselt number (Nu) and friction factor (f) for different rib configurations have been summarized in order so that it can be accessed for future research. 3-D CFD analysis is carried out to gain insight into the flow pattern of various V-ribbed SAH, and with the help of streamlines and contours, the findings are established. Furthermore, various exergy destruction has been studied in detail for different V-rib configurations, namely– V-rib, multiple V-rib, and multiple V-rib with the gap, and analyzed in detail for prospective studies. Exergetic performance study of these rib configurations indicates that the multiple ribs and the multiple rib-gap combinations enhance exergetic efficiency (ηex) by 12% and 31.6%, respectively, in comparison to V-rib SAH. © 2021 Elsevier LtdItem Directional synthesis of aviation-, diesel-, and gasoline range hydrocarbon fuels by catalytic transformations of biomass components: An overview(Elsevier Ltd, 2023) Dutta, S.; Madav, V.; Joshi, G.; Naik, N.; Kumar, S.Selective conversion of heavily oxygenated biomolecules into hydrocarbon-based liquid transportation fuels with stipulated structural traits is of academic and industrial significance. This work provides an overview of producing fuel precursors from biomass components and their catalytic transformation into aviation-, diesel-, and gasoline-range hydrocarbon fuels (HCFs). Strategic applications of various organic transformations for the molecular design of targeted products have been rationalized. Construction and alteration of the carbon skeletal system in the fuel candidates via chemical-catalytic transformations have been highlighted. Emphasis has also been given to the process conditions and details of the catalysts employed in these processes. Critical analysis of the literature data presented in this review will assist the researchers in developing more proficient processes for the biorenewable production of drop-in HCFs. © 2023 Elsevier LtdItem Abrasive wear behavior of granite-filled glass-epoxy composites by SiC particles using statistical analysis(2011) Basavarajappa, .S.; Manjunath Yadav, S.M.; Kumar, S.; Arun, K.V.; Narendranath, S.This experimental investigation deals with the evaluation of abrasive wear behavior of Glass Epoxy (G-E) composites on pin-ondisc test rig. A plan of experiments, based on the Taguchi Design of Experiments, was performed to acquire data in controlled way. An orthogonal array and the analysis of variance were employed to investigate the percentage of contribution of various process parameters like sliding speed, applied load, sliding distance and their interactions affecting the abrasive wear volume loss of composites. The correlations between the various factors affecting the abrasive wear behavior of composites were obtained by using multiple linear regression equations. The obtained results indicate that applied load and sliding distance were the wear factors that have the highest physical as well as statistical influence on the abrasive wear behavior of both filled and unfilled G-E composites. A good agreement between the predicted and actual wear resistance was observed within±12%. © Taylor & Francis Group, LLC.Item Collapse mechanism of foam cored sandwich structures under compressive load(2011) Manjunath Yadav, S.M.; Arun, K.V.; Basavarajappa, .S.; Narendranath, S.; Kumar, S.In this work the moisture absorption capability, compressive properties, collapse modes of various types of composite sandwich structures are reported. The tested sandwich structures were constructed with varieties of hybridized skin materials and different compositions of the core materials. The moisture absorption, Flatwise compression and Edgewise compression tests are conducted for core as well as sandwich structures. Comparisons of results have been between the hybridized and non-hybridized sandwich structures. Two modes of collapse were noticed in the Edgewise compressive test, one of which being progressive end-crushing of the sandwich structure featured by significant crash energy absorption. This feature was highly desired for the parts of transportation vehicles. Microscopic analysis has been carried out to know the nature of failure under compressive loads. It has been observed that with increasing the debonding strength of the core-face interface, the failure mode changes from unstable collapse mode stable progressive crushing. © Taylor & Francis Group, LLC.Item New dihydropyridine derivatives: Anti-inflammatory, analgesic and docking studies(2013) Ulloora, S.; Kumar, S.; Shabaraya, R.; Vasudeva Adhikari, A.V.The present article describes synthesis of new diethyl 2,6-dimethyl-4-(4- (2-substituted amino-2-oxoethoxy) phenyl)-1,4-dihydropyridine-3,5-dicarboxylates (6a-10b) following multistep synthetic route. Structures of newly synthesized intermediates and title compounds were established by spectral and elemental analyses. The final compounds were screened for their in vivo anti-inflammatory and analgesic activities by carrageenan-induced paw oedema and tail immersion methods, respectively. Moreover, molecular docking studies were carried out for active compounds 6c, 6d, 7d, 8 and 10b to study their mode of action, meanwhile in vivo results indicated that these compounds displayed rapid onset of anti-inflammatory action and exhibited prominent activity when compared with the standard drug. Compounds 6d and 7d carrying amide functionality showed the highest anti-inflammatory as well as analgesic activities. The molecular docking results emphasised the in vivo data and all docked molecules were found to display very low binding constant values in nanomolar scale. © 2012 Springer Science+Business Media, LLC.Item On graceful unicyclic wheels(Charles Babbage Research Centre, 2014) Hegde, S.M.; Kumar, S.A digraph D with e edges is labeled by assigning a distinct integer value ?(?) from (0, l,...,e) to each vertex ?. The vertex values, in turn, induce a value 0(?) ?) on each edge (?, ?) where ? (?, ?) = ?(?) - ? (?)mod(e + 1). If the edge values are all distinct and nonzero, then the labeling is called a graceful labeling of a digraph. In 1985, Bloom and Hsu conjectured that " All unicyclic wheels are gracefulIn this paper we prove the conjecture. © © 2014, Charles Babbage Research Centre.Item Energy storage and management in supercapacitors for application in piezoelectric energy harvesting systems(Sphinx Knowledge House info@sphinxsai.com, 2015) Sripad, S.; Kumar, S.; Jain, A.Electrical double layer capacitors (supercapacitors) were fabricated using activated carbon as the active material and polyvinylidine fluoride (PVDF) as a binder with a suitable conductive additive (MWCNTs) together in an optimized ratio. The supercapacitor cells were assembled using an aqueous solution of 0.5M Na2SO4 as the electrolyte. These cells had an average capacitance of 1.7F each as measured by the constant current charging method. The two electrode symmetric cell had a specific capacitance of 23.05 F/g. The fabrication methodology has been discussed as well as the potential applications of the supercapacitor in piezoelectric element based energy harvesting systems have been elucidated. © 2015, International Journal of ChemTech Research. All rights reserved.Item Comparative study of simulation and experimentation for the u-value of double-glazed windows with inter-pane blinds(Taylor and Francis Inc. 325 Chestnut St, Suite 800 Philadelphia PA 19106, 2015) Sharda, A.; Kumar, S.This article applies the Taguchi design on a simulation as well as on an experimentation technique to determine the thermal transmittance (U-value) of a double-glazed window with inter-panes blinds so as to explore its performance potential for a particular Indian climate. Environmental parameters are selected per the composite climate in India. Simulated results show a maximum of 20% variation when compared with experimental ones. Analysis of results shows that Taguchi methods are effective in ranking the effect of various parameters on the U-value of identified glazing units. The low-emissivity glazing system ranks first, followed by slat angle, temperature difference, pane spacing, and temperature of hotplate (representing climatic conditions). The analysis of means is also carried out to identify the best combination of levels of various parameters. ©2015 ASHRAE.Item Magnetic resonance image denoising using nonlocal maximum likelihood paradigm in DCT-framework(John Wiley and Sons Inc, 2015) Kumar, P.K.; Darshan, P.; Kumar, S.; Ravindra, R.; Rajan, J.; Saba, L.; Suri, J.S.The data acquired by magnetic resonance (MR) imaging system are inherently degraded by noise that has its origin in the thermal Brownian motion of electrons. Denoising can enhance the quality (by improving the SNR) of the acquired MR image, which is important for both visual analysis and other post processing operations. Recent works on maximum likelihood (ML) based denoising shows that ML methods are very effective in denoising MR images and has an edge over the other state-of-the-art methods for MRI denoising. Among the ML based approaches, the Nonlocal maximum likelihood (NLML) method is commonly used. In the conventional NLML method, the samples for the ML estimation of the unknown true pixel are chosen in a nonlocal fashion based on the intensity similarity of the pixel neighborhoods. Euclidean distance is generally used to measure this similarity. It has been recently shown that computing similarity measure is more robust in discrete cosine transform (DCT) subspace, compared with Euclidean image subspace. Motivated by this observation, we integrated DCT into NLML to produce an improved MRI filtration process. Other than improving the SNR, the time complexity of the conventional NLML can also be significantly reduced through the proposed approach. On synthetic MR brain image, an average improvement of 5% in PSNR and 86%reduction in execution time is achieved with a search window size of 91 × 91 after incorporating the improvements in the existing NLML method. On an experimental kiwi fruit image an improvement of 10% in PSNR is achieved. We did experiments on both simulated and real data sets to validate and to demonstrate the effectiveness of the proposed method. © 2015 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 25, 256-264, 2015 © 2015 Wiley Periodicals, Inc.