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排序方式: 共有487条查询结果,搜索用时 62 毫秒
441.
Rajat Gupta 《International journal of occupational safety and ergonomics》2013,19(4):613-621
Traditional safety and health system measurement procedures, practiced in various industries produce qualitative results with a degree of uncertainty. This paper presents a fuzzy-logic-based approach to developing a fuzzy model for assessing the safety and health status in the tea industry. For this, the overall safety and health status at a tea estate has been considered as a function of 4 inputs: occupational safety, occupational health, behavioral safety and competency. A set of fuzzy rules based on expert human judgment has been used to correlate different fuzzy inputs and output. Fuzzy set operations are used to calculate the safety and health status of the tea industry. Application of the developed model at a tea estate showed that the safety and health status belongs to the fuzzy class of good with a crisp value of 7.2. 相似文献
442.
Bhide M Gupta P 《Journal of environmental biology / Academy of Environmental Biology, India》2006,27(4):745-751
In the present investigation egg capsules of Gyraulus convexiusculus were treated with different concentrations of baygon. A dose and duration dependent deviations in the number of negatively charged protein fractions in the trochophore and veliger larval stages were observed. It resulted into anomalies in the morphogenesis and organogenesis of corresponding larval stages. Most of the protein bands showed the decrease in the protein positive intensities in comparison to control. This suggested that baygon causes larval toxicity in Gyraulus convexiusculus. 相似文献
443.
Kumar A Gupta AK 《Journal of environmental biology / Academy of Environmental Biology, India》2006,27(1):89-92
In the present study short-term (96 hr) toxicity of mercury in relation to water hardness (270 and 560 mg/l) and temperature (16 degrees C and 35 degrees C) to the fingerlings of Indian major carps, i.e. catla, rohu and mrigal has been evaluated using static bioassay. The LC5o indicates that both water hardness and temperature played significant role in mercury toxicity. The test fishes were found most resistant with water hardness of 560 mg/l at 16 degrees C as compared to that of water hardness of 560 mg/l at 35 degrees C and water hardness of 270 mg/l at both the temperatures, i.e. 35 and 16 degrees C. Whereas the order of relative sensitivities of these fishes for mercury ions were recorded as catla>rohu>mrigal. The safe concentrations of mercury were ranged in between 12.133 to 19.689 microg/l for catla; 64.039 to 82.555 microg/l for rohu and 73.510 to 89.585 microg/l for mrigal for both the water hardness and temperature. 相似文献
444.
Mahesh Kumar Sahu Ashim Das Gupta 《Journal of the American Water Resources Association》2001,37(3):675-684
ABSTRACT: Operation of a storage‐based reservoir modifies the downstream flow usually to a value higher than that of natural flow in dry season. This could be important for irrigation, water supply, or power production as it is like an additional downstream benefit without any additional investment. This study addresses the operation of two proposed reservoirs and the downstream flow augmentation at an irrigation project located at the outlet of the Gandaki River basin in Nepal. The optimal operating policies of the reservoirs were determined using a Stochastic Dynamic Programming (SDP) model considering the maximization of power production. The modified flows downstream of the reservoirs were simulated by a simulation model using the optimal operating policy (for power maximization) and a synthetic long‐term inflow series. Comparing the existing flow (flow in river without reservoir operation) and the modified flow (flow after reservoir operation) at the irrigation project, the additional amount of flow was calculated. The reliability analysis indicated that the supply of irrigation could be increased by 25 to 100 percent of the existing supply over the dry season (January to April) with a reliability of more than 80 percent. 相似文献
445.
Archana Gupta Georgia Destouni Marina Bergen Jensen 《Journal of contaminant hydrology》1999,35(4):261
Subsurface solute transport through structured soil is studied by model interpretation of experimental breakthrough curves from tritium and phosphorus tracer tests in three intact soil monoliths. Similar geochemical conditions, with nearly neutral pH, were maintained in all the experiments. Observed transport differences for the same tracer are thus mainly due to differences in the physical transport process between the different monoliths. The modelling is based on a probabilistic Lagrangian approach that decouples physical and chemical mass transfer and transformation processes from pure and stochastic advection. Thereby, it enables explicit quantification of the physical transport process through preferential flow paths, honouring all independently available experimental information. Modelling of the tritium breakthrough curves yields a probability density function of non-reactive solute travel time that is coupled with a reaction model for linear, non-equilibrium sorption–desorption to describe the phosphorus transport. The tritium model results indicate that significant preferential flow occurs in all the experimental soil monoliths, ranging from 60–100% of the total water flow moving through only 25–40% of the total water content. In agreement with the fact that geochemical conditions were similar in all experiments, phosphorus model results yield consistent first-order kinetic parameter values for the sorption–desorption process in two of the three soil monoliths; phosphorus transport through the third monolith cannot be modelled because the apparent mean transport rate of phosphorus is anomalously rapid relative to the non-adsorptive tritium transport. The occurrence of preferential flow alters the whole shape of the phosphorus breakthrough curve, not least the peak mass flux and concentration values, and increases the transported phosphorus mass by 2–3 times relative to the estimated mass transport without preferential flow in the two modelled monoliths. 相似文献
446.
K.D.P. Nigam R.K. Srivastav S.K. Gupta P. Vasudevan 《Environmental Modeling and Assessment》1998,3(4):249-258
A mathematical model is developed for metal ions uptake by aquatic plants. The model is based on a mechanism which assumes
that the complex biological substances present in the plant react with the metal ions to form complexes of these ions at the
solution–plant interface, and then the metal complexes diffuse through a membrane towards the bulk phase of the plant because
of the concentration gradients present in the membrane. The model predicts the decreasing capacity of the plants for metal
ions uptake as the contact time between the solution and the plant is increased. Experiments are conducted in the laboratory
for the removal of chromium, copper, iron, nickel, lead and zinc by measuring metal ions uptake by two aquatic plants, Salvinia
and Spirodela, in the solution of these metal ions of concentration ranging from 1 to 8 ppm. After estimating the parameters
of the model, it is used for predicting the metal ions concentration in the solution as a function of time and the metal ions
concentration inside the plants after 14 days of contact time. The comparison of the model predictions with the experimental
results shows excellent agreement. The above model may be used for design and analysis of an aquatic‐plant‐based waste water
treatment system.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
447.
The objective of the study is to investigate seasonal and spatial variations of PM10 (particulate matter with aerodynamic diameter less than or equal to 10 μm) and TSP (total suspended particulate matter) of
an Indian Metropolis with high pollution and population density from November 2003 to November 2004. Ambient concentration
measurements of PM10 and TSP were carried out at two monitoring sites of an urban region of Kolkata. Monitoring sites have been selected based
on the dominant activities of the area. Meteorological parameters such as wind speed, wind direction, rainfall, temperature
and relative humidity were also collected simultaneously during the sampling period from Indian Meteorological Department,
Kolkata. The 24 h average concentrations of PM10 and TSP were found in the range 68.2–280.6 μg/m3 and 139.3–580.3 μg/m3 for residential (Kasba) area, while 62.4–401.2 μg/m3 and 125.7–732.1 μg/m3 for industrial (Cossipore) area, respectively. Winter concentrations of particulate pollutants were higher than other seasons,
irrespective of the monitoring sites. It indicates a longer residence time of particulates in the atmosphere during winter
due to low winds and low mixing height. Spread of air pollution sources and non-uniform mixing conditions in an urban area
often result in spatial variation of pollutant concentrations. The higher particulate pollution at industrial area may be
attributed due to resuspension of road dust, soil dust, automobile traffic and nearby industrial emissions. Particle size
analysis result shows that PM10 is about 52% of TSP at residential area and 54% at industrial area. 相似文献
448.
Michel Mench Jean-Paul Schwitzguébel Peter Schroeder Valérie Bert Stanislaw Gawronski Satish Gupta 《Environmental science and pollution research international》2009,16(7):876-900
Purpose
The term “phytotechnologies” refers to the application of science and engineering to provide solutions involving plants, including phytoremediation options using plants and associated microbes to remediate environmental compartments contaminated by trace elements (TE) and organic xenobiotics (OX). An extended knowledge of the uptake, translocation, storage, and detoxification mechanisms in plants, of the interactions with microorganisms, and of the use of “omic” technologies (functional genomics, proteomics, and metabolomics), combined with genetic analysis and plant improvement, is essential to understand the fate of contaminants in plants and food, nonfood and technical crops. The integration of physicochemical and biological understanding allows the optimization of these properties of plants, making phytotechnologies more economically and socially attractive, decreasing the level and transfer of contaminants along the food chain and augmenting the content of essential minerals in food crops. This review will disseminate experience gained between 2004 and 2009 by three working groups of COST Action 859 on the uptake, detoxification, and sequestration of pollutants by plants and consequences for food safety. Gaps between scientific approaches and lack of understanding are examined to suggest further research and to clarify the current state-of-the-art for potential end-users of such green options. 相似文献449.
Nirankar Singh Ravinder Agarwal Amit Awasthi Prabhat K. Gupta Susheel K. Mittal 《Atmospheric environment (Oxford, England : 1994)》2010,44(10):1292-1300
Aerosol (total suspended particulate) samples collected at three diverse locations (urban-commercial, semi-urban and rural-agricultural) in Patiala, India were analyzed for loss on ignition (LOI) and organic tarry matter (OTM) content in ambient air during crop residue burning (CRB) episodes and non-crop residue burning (NCRB) months in 2006–2007. Results showed high levels of LOI and OTM during wheat and rice crop residue-burning periods at all the sites. Higher levels were obtained during rice crop residue-burning period as compared to the wheat residue-burning period. At semi-urban site, LOI varied between 53 ± 36 μg m?3 and 257 ± 14 μg m?3 constituting 38–78% (w/w) part of the aerosols whereas levels of OTM varied between 0.98 ± 0.11 μg m?3 and 7.93 ± 2.76 μg m?3 comprising 0.42–3.28% (w/w) fraction. At rural-agricultural area site, levels of LOI varied between 86 ± 40 μg m?3 and 293 ± 70 μg m?3 comprising 27–84% (w/w), whereas OTM levels varied between 1.31 ± 0.64 μg m?3 and 10.09 ± 6.56 μg m?3 constituting 0.83–2.42% (w/w) fraction of the aerosols. At urban-cum-commercial site, levels of LOI and OTM varied between 48 ± 23 μg m?3 and 281 ± 152 μg m?3 and 2.53 ± 1.23 μg m?3 and 17.40 ± 8.50 μg m?3, constituting 24–62% (w/w) part of the aerosols, respectively. Results also indicated that OTM and LOI were integral parts of aerosols and their concentrations were influenced by the crop residue burning practices with incorporated effect of vehicular activities in Patiala. 相似文献
450.