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Resampling is the technique of manipulating a digital image and transforming it into another form. This manipulation could
be for various reasons - change of resolution, change of orientation, i.e. rotation, change of sampling points, etc. This
technique is used extensively in image processing for all applications, including medical, industrial and of course in remote
sensing. This is because the image as it is captured will have limitations imposed by the imaging geometry or camera. However,
for analysis, we would like to have the image in a different and better form. By this technique, we are trying to achieve
what we are not able to achieve by the imaging process. Thus, if we consider remote sensing data, the data acquired will have
the constraints imposed by the satellite orbit, payload, etc. However, for applications, the input resolution might not be
sufficient. Besides, the image will be acquired in a way consistent with the orbit. Thus in the case of sun synchronous orbits,
the images are always inclined to true North. Besides, the images will have inherent distortions due to the peculiar characteristics
of the payload and the relative geometry with the earth. However, for extraction of correct information from these images,
these distortions have to be removed. Besides, if we are to compare these images with maps, the sampling intervals have to
be made uniform, and the data put in proper map projections. All these call for resampling of the input image. So far, we
have been using either the cubic convolution or nearest neighbor method in all the data products generated from the IRS (Indian
Remote Sensing ) series of satellites. These two methods were sufficient for the data we have been getting till now. However,
with the impending launch of TES (Technology Experiment Satellite) and 1RS P6, we are entering an era of obtaining very high-resolution
data. Manipulating such data needs improved resampling algorithms. To this end, this paper surveys the existing methods of
resampling and describes some experiments that were carried out to evaluate the various methods, and finally concludes on
the method to be adopted for the IRS program under consideration. 相似文献
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Measurements of river water quality at Haridwar, India, taken during 2005–2006 show that the river water does not meet the World Health Organization and Bureau of Indian Standards criteria of drinking water quality, especially with respect to total coliform and fecal coliform. This study investigates the removal of pathogens at a river bank filtration site in Haridwar. Using the quality of river water and the quality of abstracted water from a nearby production well, semi‐empirical models based on the concept of filtration coefficient are developed and tested for their effectiveness in removing pathogens under varying bacteriological quality of source water. A two‐tier model, which includes the effect of clogged layer, is developed to obtain an equivalent filtration coefficient. This coefficient is found to be linearly related with natural logarithm of the concentration of pathogens in the source water. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
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Formulation, application and evaluation of a stack emission model for coal-based power stations 总被引：1，自引：1，他引：0
P. P. Walvekar B. R. Gurjar 《International Journal of Environmental Science and Technology》2013,10(6):1235-1244
Estimation of coal power plant emissions is a vital step to visualise emission trends with respect to specific policy implementations and technological interventions so that their effectiveness in terms of emission reductions and ambient air quality improvement can be quantitatively assessed. However, research work concerning stack emission estimations specifically for coal power plants in India is limited. To bridge the present gap, we present a plant-specific multi-year and multi-parameter Coal Power Stack Emission Model. This model has been developed to explore current and historical annual stack emissions from a coal-based thermal power plant taking into account essential variables such as coal characteristics, process attributes and control equipment aspects, which can significantly influence the stack emissions. This study concentrates on development of Coal Power Stack Emission model and its application for the estimation of plant and year-specific emission factors and stack emissions for a coal-based power plant at Badarpur, New Delhi, for the period of 2000–2008. The validation of Coal Power Stack Emission model has also been successfully carried out by comparing the trends of percentage change in annual emission estimates and observed ambient air concentrations of total suspended particles, PM10 and sulphur dioxide at two nearby air quality monitoring stations, namely Siri Fort and Nizamuddin. 相似文献
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Manju Mohan Yukihiro Kikegawa B. R. Gurjar Shweta Bhati Narendra Reddy Kolli 《Theoretical and Applied Climatology》2013,112(3-4):647-658
Urban heat island intensities (UHI) have been assessed based on in situ measurements and satellite-derived observations for the megacity Delhi during a selected period in March 2010. A network of micrometeorological observational stations was set up across the city. Site selection for stations was based on dominant land use–land cover (LULC) classification. Observed UHI intensities could be classified into high, medium and low categories which overall correlated well with the LULC categories viz. dense built-up, medium dense built-up and green/open areas, respectively. Dense urban areas and highly commercial areas were observed to have highest UHI with maximum hourly magnitude peaking up to 10.7 °C and average daily maximum UHI reaching 8.3 °C. UHI obtained in the study was also compared with satellite-derived land surface temperatures (LST). UHI based on in situ ambient temperatures and satellite-derived land surface temperatures show reasonable comparison during nighttime in terms of UHI magnitude and hotspots. However, the relation was found to be poor during daytime. Further, MODIS-derived LSTs showed overestimation during daytime and underestimation during nighttime when compared with in situ skin temperature measurements. Impact of LULC was also reflected in the difference between ambient temperature and skin temperature at the observation stations as built-up canopies reported largest gradient between air and skin temperature. Also, a comparison of intra-city spatial temperature variations based UHI vis-à-vis a reference rural site temperature-based UHI indicated that UHI can be computed with respect to the station measuring lowest temperature within the urban area in the absence of a reference station in the rural area close to the study area. Comparison with maximum and average UHI of other cities of the world revealed that UHI in Delhi is comparable to other major cities of the world such as London, Tokyo and Beijing and calls for mitigation action plans. 相似文献
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Journal of Seismology - Seismic catalogue preparation is one of the important steps of probabilistic seismic hazard assessment (PSHA). Catalogue preparation includes homogenization and declustering... 相似文献
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