307 research outputs found

    Use of Dynamic Programming for Reliability Engineers

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    This paper aims to obtain the optimum cost allocation to a number of components connected in series (no redundancy) with a view to maximize the system reliability subject to a given total cost of the system. The reliability of each component is a function of its cost. The technique of Dynamic Programming has been employed to achieve the results

    Chemical characteristics and source apportionment of aerosols over Indian Ocean during INDOEX-1999

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    During INDOEX IFP-99, the samples of aerosols were collected onboard ORV Sagar Kanya over Indian Ocean along the cruise track, for chemical characterization and identification of dominating sources of aerosols. The concentrations of nss-SO4, nss-Ca, nss-Mg, NO3, K, NH4 and SO2 were observed to be significantly higher before ITCZ in northern hemisphere than across ITCZ in southern hemisphere. In this study, variation of concentrations of nss-SO4, nss-Ca and nss-K with respect to change in latitude, wind direction, wind speed and relative humidity have been highlighted. North of ITCZ, nss-SO4 varied from 2.20 to 18.31 μg/m3 and south of ITCZ from 0.50 to 2.79 μg/m3 while nss-Ca varied from 0.02 to 0.72 μg/m3 north of ITCZ and from 0.01 to 0.14 μg/m3 south of ITCZ. nss-K ranged 0.09-1.43 μg/m3 and 0.07-0.60 μg/m3 before ITCZ and across ITCZ respectively. nss-Ca and nss-SO4 were contributed mainly by NNW and ENE winds while nss-K was observed to be contributed mainly by SSW and ENE winds. Wind speed greater than 4.5 m/s negatively influenced the concentration of nss-Ca concentrations. Correlation coefficients of nss-SO4 with SO2 (r = 0.7) and RH (r = 0.5) suggested a significant contribution of nss-SO4 by aqueous phase oxidation of SO2. Using PCA, four major sources namely sea salt, biogenic combustion, secondary SO4 and crustal contribution were identified over Indian Ocean during INDOEX period

    Measurements of carbonaceous aerosols at urban and remote marine sites

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    Concentrations of total carbon (TC) and black carbon (BC) in ambient air at Delhi (urban site) and over Indian Ocean (remote marine) were determined as a part of INDOEX programme. Over Indian Ocean, the TC and BC concentrations varied from 1.81 to 10.05 μg/m3 and 0.13 to 1.36 μg/m3 respectively during FFP-98. During the same season at Delhi, the TC and BC ranged from 7.50 to 40.27 μg/m3 and 0.49 to 2.84 μg/m3 respectively. In addition, at Delhi, the TC and BC concentrations were noticed very low during the monsoon season. However, the percentage BC during monsoon season was very high compared to winter season. High concentrations of TC were observed due to high organic carbon (OC) which might be due to biomass burning of various kinds. Similar to Delhi, near Indian coast, the concentration of OC was very high while towards ITCZ and across ITCZ, OC content was relatively lower

    Vertical migration of some herbicides through undisturbed and homogenized soil columns

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    A laboratory experiment was conducted by using three herbicides, two from dinitroaniline group and one from thiocarbamate group to know their degree of downward movement (leachability) through soil columns and their contribution in ground water contamination. Soil columns were loaded with Pendimethalin, Benthiocarb and Oryzalin at doses of 10.0, 10.0 and 7.7 kg/ha, respectively. After 30 days soil samples were analyzed from each segments (i.e. 0–6, 6–12, 12–18, 18–24 and 24–30 cm) for Benthiocarb and Pendimethalin by GLC equipped with Ni63 electron capture detector (ECD) and for Oryzalin by HPLC coupled with UV-VIS detector. The results obtained in the present study reveal that the residues of the three herbicides under investigation were predominantly confined to the upper soil layer (0–6 cm). Comparatively, low mobility of these herbicides in soils could be due to strong adsorption of these chemical to soil colloids

    An Investigation of a (vinylbenzyl) trimethylammonium and N-vinylimidazole-substituted poly (vinylidene fluoride-co-hexafluoropropylene) copolymer as an anion-exchange membrane in a lignin-oxidising electrolyser

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    Electrolysis is seen as a promising route for the production of hydrogen from water, as part of a move to a wider “hydrogen economy”. The electro-oxidation of renewable feedstocks offers an alternative anode couple to the (high-overpotential) electrochemical oxygen evolution reaction for developing low-voltage electrolysers. Meanwhile, the exploration of new membrane materials is also important in order to try and reduce the capital costs of electrolysers. In this work, we synthesise and characterise a previously unreported anion-exchange membrane consisting of a fluorinated polymer backbone grafted with imidazole and trimethylammonium units as the ion-conducting moieties. We then investigate the use of this membrane in a lignin-oxidising electrolyser. The new membrane performs comparably to a commercially-available anion-exchange membrane (Fumapem) for this purpose over short timescales (delivering current densities of 4.4 mA cm−2 for lignin oxidation at a cell potential of 1.2 V at 70 °C during linear sweep voltammetry), but membrane durability was found to be a significant issue over extended testing durations. This work therefore suggests that membranes of the sort described herein might be usefully employed for lignin electrolysis applications if their robustness can be improved

    Drug Susceptibility in Leishmania Isolates Following Miltefosine Treatment in Cases of Visceral Leishmaniasis and Post Kala-Azar Dermal Leishmaniasis

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    Resistance to antimonials has emerged as a major hurdle to the treatment and control of VL and led to the introduction of Miltefosine as first line treatment in the Indian subcontinent. MIL is an oral drug with a long half-life, and it is feared that resistance may emerge rapidly, threatening control efforts under the VL elimination program. There is an urgent need for monitoring treatment efficacy and emergence of drug resistance in the field. In a set of VL/PKDL cases recruited for MIL treatment, we observed comparable drug susceptibility in pre- and post-treatment isolates from cured VL patients while MIL susceptibility was significantly reduced in isolates from VL relapse and PKDL cases. The PKDL isolates showed higher tolerance to MIL as compared to VL isolates. Both VL and PKDL isolates were uniformly susceptible to PMM. MIL transporter genes LdMT/LdRos3 were previously reported as potential resistance markers in strains in which MIL resistance was experimentally induced. The point mutations and the down-regulated expression of these transporters observed in vitro could, however, not be verified in natural populations of parasites. LdMT/LdRos3 genes therefore, do not appear to be suitable markers so far for monitoring drug susceptibility in clinical leishmanial isolates
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