We employ an Artificial Neural Network (ANN) based technique to develop a pipeline for automated segregation of stars from the galaxies to be observed by Tel-Aviv University Ultra-Violet Experiment (TAUVEX). We use synthetic spectra of stars from UVBLUE library and selected International Ultraviolet Explorer (IUE) low-resolution spectra for galaxies in the ultraviolet (UV) region from 1250 to 3220 Å as the training set and IUE low-resolution spectra for both the stars and the galaxies as the test set. All the data sets have been pre-processed to get band integrated fluxes so as to mimic the observations of the TAUVEX UV imager. We also perform the ANN based segregation scheme using the full length spectral features (which will also be useful for the ASTROSAT mission). Our results suggest that, in the case of the non-availability of full spectral features, the limited band integrated features can be used to segregate the two classes of objects; although the band data classification is less accurate than the full spectral data classification. 相似文献
Contamination of groundwater by nitrates leaching from intensive agricultural and livestock operations have become a major concern for surrounding communities that use groundwater as their water supply. High levels of nitrate in drinking water poses a significant risk to human health, i.e., methaemoglobinaemia (“blue baby” syndrome).
The traditional pump-and-treat method is ineffective in medium to fine-textured agricultural soils due to the low hydraulic conductivity. This paper presents the results of a laboratory experiment investigating the feasibility of using electrokinetic treatment in retaining, accumulating, moving and remediating nitrates in a silty loam soil under hydraulic gradients.
A hydraulic gradient of 1.25 was applied to the horizontal soil columns to simulate a groundwater movement system. The study was performed in two stages. During the first stage of the experiment, the anode located at the inflow end of the columns was able to retard the movement of nitrates even under a hydraulic gradient of 1.25. After 15 days of flow, the effluent nitrate concentration in the control column rose to 90 mg l−1 while no nitrates were detected in the effluent from columns subjected to the electrokinetic treatment.
After 15 days, the polarity of the electrodes was switched and this second stage lasted another 20 days. The cathode near the inflow end promoted the conversion of nitrates entering the column to other forms. The anode near the outflow end promoted the migration and accumulation of negatively charged nitrate ions towards the outflow end. By the 12th day, the nitrate concentrations in the electrokinetically treated columns were brought down to <5 mg NO3-N l−1. Electrokinetic treatment retarded nitrate movement against a hydraulic gradient of 1.25 and effectively restored a medium-textured soil contaminated with NO3-N.
The NO2-N level remained below 1 mg l−1 throughout the experiment. The hydraulic conductivity varied between 1.0E–7 and 3.6E–7 m s−1. The current requirement varied between 3 and 6 mA. 相似文献
The Advanced WiFS sensor of RESOURCESAT- 1 satellite offers significantly improved specifications compared to the WiFS sensor
onboard IRS IC, P3 and ID satellites. The improvements are in terms of spatial resolution, radiometry (quantisation levels)
and number of spectral bands. In the present study, an attempt has been made to quantify the gains due to these enhanced specifications.
The study has been carried out in a predominantly agricultural area. For the study reported here, one set of overlapping data
acquired on the same day by WiFS and AWiFS sensors has been selected. This eliminates the need of atmospheric correction/
normalization for comparison. The effect of spatial resolution has been studied by applying ISODATA spectral clustering algorithm
with number of clusters set at three different levels, viz., 10, 20 and 30. They are assumed to mimic first, second and third
level classification, respectively. Output images were filtered using 3 × 3 majority filter. Homogeneous polygons having area
less than 1/2 and 1 pixel of WiFS were recorded. This indicates the minimum loss by using WiFS data. A relative gain of 10
– 15 % is observed due to improvement in spatial resolution. For comparison of radiometry, local variance measure was used.
It was observed that local variance is much larger for AWiFS data in comparison with WiFS data. This indicates presence of
enhanced local contrast, hence heterogeneity, in AWiFS data over WiFS data. Separability analysis has been carried out to
demonstrate improvements due to two additional spectral bands (Green and SWIR). 相似文献
The understanding of geotechnical characteristics of near-surface material is of fundamental interest in seismic microzonation.
Shear wave velocity (Vs), one of the most important soil properties for soil response modeling, has been evaluated through
seismic profiling using the multichannel analysis of surface waves in the city of Dehradun situated along the foothills of
northwest Himalaya. Fifty sites in the city have been investigated with survey lines between 72 and 96 m in length. Multiple
1-D and interpolated 2-D profiles have been generated up to a depth of 30–40 m. The Vs were used in the SHAKE2000 software
in combination with seismic input motion of the recent Chamoli earthquake to obtain site response and amplification spectra.
The estimated Vs are higher in the northern part of the study area (i.e., 200–700 m/s from the surface to a depth of about
30 m) as compared to the south and southwestern parts of the city (i.e., 180–400 m/s for the same depth range). The response
spectra suggest that spectral acceleration values for two-story structures are three to eight times higher than peak ground
acceleration at bedrock. The analysis also suggests peak amplification at 3–4, 2–2.5, and 1–1.5 Hz in the northern, central,
and south-southwestern parts of the city, respectively. The spatial distributions of Vs and spectral accelerations provide
valuable information for the seismic microzonation in different parts of the urban area of Dehradun. 相似文献
Continental weathering plays a dominant role in regulating the global carbon cycle, soil chemistry and nutrient supply to oceans. The CO2-mediated silicate weathering acts as a major CO2 sink, whereas sulphuric acid-mediated carbonate dissolution releases CO2 to the atmosphere–ocean system. In this study, dissolved major ions and silica concentrations of two tropical (Damodar and Subarnarekha) river systems from India have been measured to constrain the type and rate of chemical weathering for these basins. The total dissolved solids (TDS) of these rivers, a measure of total solute supply from all possible sources, are about 2–3 times higher than that of the global average for rivers. Mass balance calculations involving inverse modelling estimate that 63 ± 11% of total cations are derived from rock weathering, of which 27 ± 7% of cations are supplied through silicate weathering. The sulphide-S concentrations are estimated by comparing the water chemistry of these two rivers with that of a nearby river (Brahmani) with similar lithology but no signatures of sulphide oxidation. The outflows of Damodar and Subarnarekha rivers receive 17% and 55% of SO4 through sulphide oxidation, respectively. The sulphide oxidation fluxes from the ore mining areas, such as upper Damodar (0.52 × 109 mol/yr) and lower Subarnarekha (0.66 × 109 mol/yr) basins, are disproportionally (~9 times) higher compared to their fractional areal coverage to the global drainage area. The corresponding CO2 release rate (2.84 × 104 mol/km2/yr) for the Damodar basin is lower by five times than its CO2 uptake rate (1.38 × 105 mol/km2/yr). The outcomes of this study underscore the dominance of sulphide oxidation in controlling the dissolved chemical (cationic and sulphur) fluxes. 相似文献
Linear trends of anomalously high gold values in the Florida Canyon gold deposit, Nevada have been identified using a combination
of contour maps of gold (Au) concentration developed with a geographic information system (GIS) and variogram maps created
using a geostatistical analysis package. These linear trends are interpreted to represent major fault zones that exerted a
prinicipal control on gold mineralization and therefore imparted a spatial anisotropy to gold concentrations. 相似文献
This paper reports the measurement of radon concentration in well water at the site of Jalpaiguri (26°32′N, 88°46′E) near
the active fault zone of West Bengal, India. Radon concentration has been measured in well water with the help of solid-state
nuclear track detectors (SSNTD). The study indicates a positive correlation between radon anomaly and earthquake. The data
of radon content in well water have been compared with that in soil gas at the same site. 相似文献