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Articles by D.V. Singh
Total Records ( 2 ) for D.V. Singh
  B. Singh , D. Katiyar , D.V. Singh , A.K. Kashyap and A.M. Lall
  Rice fields are one of the major biogenic sources of atmospheric methane. Apart from this contribution to the greenhouse effect, rice paddy soil represents a suitable model system to study fundamental aspects of microbial ecology, such as diversity, structure and dynamics of microbial communities as well as structure function relationships between microbial groups. The present study was conducted in rainfed rice fields planted to rice (Oryza sativa) cultivar, NDR-97, to evaluate the variation of population of Methane Oxidizing Bacteria (MOB) in different soil type (Bare, Bulk and rhizosphere) over a period of 13 weeks. Urea was the only fertilizer applied, at a rate of 100 kg N ha-1 in three split doses. The experiment was laid out in a randomized complete block design with three replicate plots for treatments. The soil exhibited higher numbers of MOB in control plots of bulk and rhizospheric (37.4x106 and 58.87x106 cells g-1 dry soil) than in plots treated with urea (28.6x106 and 51.9x106 cells g-1 dry soil) at 80 Days after Sowing (DAS) and were highest in the rhizospheric soil (58.87x106 cells g-1 dry soil) followed by bulk (37.4x106 cells g-1 dry soil) and bare (2.2x106 cells g-1 dry soil) in unfertilized soil but bare (control) soil was attained highest MOB (2.7x106 cells g-1 dry soil) on 40 DAS and MOB significantly decreased in fertilized soil. The concentrations of NH4+-N were significantly (p<0.05) lower in the rhizosphere (1.3 μg g-1 soil) than in bulk (3.7 μg g-1 soil) and bare soils (4.1 μg g-1 soil) on 80 DAS in unfertilized plots. In fertilized soil NH4+-N concentration were increased due to lower number of population at different day’s intervals. The study suggests that the development of the rice rhizosphere brings about a spatial pattern in the distribution of methanotrophic bacteria which increases in size, over time; within the rhizosphere and adjoining bulk soil and that the rhizosphere is a potential microsite of methanotrophic bacterial activity.
  Amit Goyal , Gulshan Taneja and D.V. Singh
  Problem statement: In this study we investigated the probabilistic analysis of a three unit system working in a sugar Mill, wherein one unit is big and the other two units are small and identical, is examined. Upon failure of the big unit, both small units are made operative and failed unit is undertaken for repair immediately. Priority for operation is given to the big unit. Priority for repair is given to big unit if both types (i.e., big and small) of units are in queue to get the repair done. System is able to work with full capacity only if big unit or both small units are in good condition. If only one small unit is operable, the system works at reduced capacity. The system under consideration goes to rest during the non-seasonal period. Approach: System was analyzed by making use of semi-Markov processes and regenerative point technique and various measures of the system effectiveness are obtained including the profit incurred to the system. Results: Graphs had been plotted to depict the behavior of the profit with respect to failure rate for different values of repair rate and with respect to revenue per unit up time for which system is working at full capacity for different values of cost for PM/CM. Conclusion: The profit increases with the decrease in the values of the failure rate and with the increase in the values of revenue per unit up time. It has lower (higher) values on increasing the values of cost (repair rate). Cut-off points obtained for failure rate help decide about having the system with failure rate lesser than that the value at cut-off point. Also, the price of the product should be fixed in such a way so as to get the revenue greater than the value at cut-off point.
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