Intrusion and upliftment of Mahakoshal rocks between Vindhyan and Gondwana in Narmada Son Lineament, Central India     

G. K. Ghosh  C. L. Singh 《Journal of the Geological Society of India》2013,81(4):556-564

The Narmada-Son Lineament (NSL) is one of the most prominent geomorphic features in Central India, which, divides the Indian Peninsula into two parts, northern and southern India. The present study carried near the Shahdol-Katni area of Narmada-Son lineament situated in complex transition zone, encompasses with seismically active, robust changes of gravity-magnetic field, undulating sub-surface topography, existence of hot springs and complex geological setting, which, cause the resettlement of inner dynamic progression. The area covers a range of diverse formations viz. alluvial, Deccan traps, Gondwana, Vindhyan and Mahakoshal groups with different ages. Geologically the area is divided into two parts, Vindhyan and Gondwana. The Vindhyan are exposed in the northern part and Gondwana are exposed in the southern part. It can be inferred that the Mahakoshal rocks are non-magnetic and reasonably higher density rocks which are exposed and intruded in between the Vindhyan and Gondwana rocks during the crustal resetting processes, which, may cause changes in magnetic field in the central part near Tala-Barhi area. Based on magnetic data, the area can also be divided into two parts, the northern part containing higher magnetic values (upto 900 nTesla) and the southern part with the values upto -1000 nTesla. The resettlement process may cause the separation of Vindhyan and Gondwana rocks because of the two existing active faults viz. Son Narmada North Fault (SNNF) and Son Narmada South Fault (SNSF). To know the geological setting of the Narmada Son Lineament, the knowledge of basement depth study plays a major role for understanding the inner mechanism of structural scenery of the ground sub-surface. There are number of studies carried out in and around the study area, but present technique plays an important role with sufficient evidences to validate the structural setting carried by the earlier geoscientists. Werner and Euler deconvolution techniques have been jointly carried out over the study area on the available magnetic dataset for basement depth estimation. As per study, the basement depth varies from 4 km to 5 km in the central part compared to both the split ends of the profiles, which, convincingly correlate the consequences carried by earlier studies. As the magnetic method can provide a non-unique solution, it is always recommended for integrated approach for better understanding and substantiation.  相似文献   

Variogram Fractal Dimension Based Features for Hyperspectral Data Dimensionality Reduction   总被引：1，自引：0，他引：1  

Kriti Mukherjee  Jayanta K Ghosh  Ramesh C. Mittal 《Journal of the Indian Society of Remote Sensing》2013,41(2):249-258

In this paper a new approach for fractal based dimensionality reduction of hyperspectral data has been proposed. The features have been generated by multiplying variogram fractal dimension value with spectral energy. Fractal dimension bears the information related to the shape or characteristic of the spectral response curves and the spectral energy bears the information related to class separation. It has been observed that, the features provide accuracy better than 90 % in distinguishing different land cover classes in an urban area, different vegetation types belonging to an agricultural area as well as various types of minerals belonging to the same parent class. Statistical comparison with some conventional dimensionality reduction methods validates the fact that the proposed method, having less computational burden than the conventional methods, is able to produce classification statistically equivalent to those of the conventional methods.  相似文献   

Earthquake-induced built-up damage identification using IRS-P6 data: a comparative study using fuzzy-based classifiers     

Sandeep Singh Sengar  Anil Kumar  Sanjay Kumar Ghosh  Hans Raj Wason 《国际地球制图》2013,28(2):211-225

The 8 October 2005 earthquake caused widespread destruction in both the state of Jammu and Kashmir of India and Northern Pakistan. Due to poor accessibility in the hazardous and difficult mountainous terrain, a proper and comprehensive ground-based survey was not possible. However, with the help of remote sensing data and its analysis techniques, it is feasible to undertake both earthquake-related damage identification and assessment. This study attempts to document and identify built-up damaged (BD) areas using spectral indices taking temporal multispectral images from IRS-P6 LISS-IV. Five spectral indices have been used to identify BD areas using supervised possibilistic c-means (PCM) and noise cluster (NC) classifiers, to analyse the satellite data. The result indicates that Class Based Sensor Independent (CBSI) based Transformed Normalized Difference Vegetation Index (TNDVI) temporal indices provide the best results for identifying BD areas, while Simple Ratio (SR) index gives the best results for built-up undamaged area identification. Further, it observed that PCM classifier performed better in comparison to NC classifier.  相似文献   

Higher dimensional thick domain wall in Lyra geometry     

F. Rahaman  P. Ghosh  S. Shekhar  S. Mal 《Astrophysics and Space Science》2003,286(3-4):373-379

An exact solution is obtained for a thick domain wall in a five dimensional Kaluza-Klein space time within the framework of Lyra geometry. The space time is nonsingular both in its spatial and temporal behavior. It is shown that the domain wall has no particle horizon and the gravitational force due to them is attractive. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Orbital evolution measurement of the accreting millisecond X-ray pulsar SAX J1808.4-3658     

Chetana Jain  Anjan Dutta  Biswajit Paul 《Journal of Astrophysics and Astronomy》2007,28(4):197-206

We present results from a pulse timing analysis of the accretion-powered millisecond X-ray pulsar SAX J1808.4-3658 using X-ray data obtained during four outbursts of this source. Extensive observations were made with the proportional counter array of the Rossi X-ray Timing Explorer (RXTE) during the four outbursts that occurred in 1998, 2000, 2002 and 2005. Instead of measuring the arrival times of individual pulses or the pulse arrival time delay measurement that is commonly used to determine the orbital parameters of binary pulsars, we have determined the orbital ephemeris during each observation by optimizing the pulse detection against a range of trial ephemeris values. The source exhibits a significant pulse shape variability during the outbursts. The technique used by us does not depend on the pulse profile evolution, and is therefore, different from the standard pulse timing analysis. Using 27 measurements of orbital ephemerides during the four outbursts spread over more than 7 years and more than 31,000 binary orbits, we have derived an accurate value of the orbital period of 7249.156862(5) s (MJD = 50915) and detected an orbital period derivative of (3.14 ± 0.21) × 10⁻¹² s s⁻¹. We have included a table of the 27 mid-eclipse time measurements of this source that will be valuable for further studies of the orbital evolution of the source, especially with ASTROSAT. We point out that the measured rate of orbital period evolution is considerably faster than the most commonly discussed mechanisms of orbital period evolution like mass transfer, mass loss from the companion star and gravitational wave radiation. The present time scale of orbital period change, 73 Myr is therefore likely to be a transient high value of period evolution and similar measurements during subsequent outbursts of SAX J1808.4-3658 will help us to resolve this.  相似文献   

Uranium mineralisation in carbonate rocks from the upper part of Krol formation in Nainital syncline and its significance for uranium exploration in lesser Himalaya     

K. K. Sinha  Dibakar Ghosh  S. D. Rai  M. K. Khandelwal 《Journal of the Geological Society of India》2016,88(3):295-304

Low grade uranium mineralisation associated with phosphorites/ phosphatic sediments and carbonaceous shale has been well established at and/or close to Krol- Tal contact in some of sub-basins of inner Krol belt such as Nigalidhar, Mussoorie and Garhwal synclines in the realm of lesser Himalaya. Unlike the other sub-basins of the belt, though the Nainital syncline is sparsely phosphatic and carbonaceous, carbonate hosted uranium occurrence is reported for the first time from the syncline. The carbonate-hosted uranium occurrences in Krol D of Nainital syncline are of limited extent with values ranging from 200 ppm to 840 ppm eU3O8. Radioactivity is associated with fractured dolostone/ dolomitic limestone and pelloidal limestone. Uranium phases mostly occur in association with carbonaceous, ferruginous matters and clays. However, ultrafine pitchblende grains do occur associated with idiotopic pyrite aggregates suggesting initial trapping of uranium by organic matters present in sediments which later remobilised and precipitated as fine pitchblende. Subsequently, second phase of remobilisation of uranium under oxidising condition gave rise uraniferous goethite, limonite and other iron oxyhydoxides. In contrast to other sub-basins, the Krol-Tal contact in Nainital syncline does not appear to hold any promising phosphate and uranium mineralisation due to less suitable basinal morphology and low Ca/Mg ratio.  相似文献   

Digital image processing of multispectral ASTER imagery for delineation of alteration and related clay minerals in Sakoli belt: Maharashtra – A case study     

Uday Kumar Ghosh  K. K. Naik  M. P. Kesari 《Journal of the Geological Society of India》2016,88(4):464-470

The extraction of spectral signature through remote sensing data in geological studies is very limited in Indian terrain. The present research is an attempt to delineate alteration and associated minerals using high resolution multispectral advanced space borne thermal emission and reflection (ASTER) data in Sakoli volcano-sedimentary sequence. The alteration zones are generally associated with certain types of mineral and mineral aggregates and are localized in the ground that can be mapped remotely using spectral mapping techniques. The band ratio and selective PCT were applied on calibrated ASTER image to extract spectral signature of index mineral. The results showed that high abundance of these minerals within pixels is corresponding to the alteration zones. The field observation, petrography and XRD analysis of the alteration zones confirmed the presence of dominant mineral phases that were identified remotely.  相似文献   

Projections of Extreme Dry and Wet Spells in the 21st Century India Using Stationary and Non-stationary Standardized Precipitation Indices     

Kaustubh Salvi  Subimal Ghosh 《Climatic change》2016,138(3-4):667-680

  相似文献   

Spatial Supermarket Redlining and Neighborhood Vulnerability: A Case Study of Hartford,Connecticut          下载免费PDF全文

Mengyao Zhang  Debarchana Ghosh 《Transactions in GIS》2016,20(1):79-100

The disinclination of chain supermarkets to locate or relocate existing stores from inner city impoverished neighborhoods to affluent suburbs is termed ‘spatial supermarket redlining’. This study attempts to map and understand the effects of potential spatial supermarket redlining on food access in urban disadvantaged neighborhoods of Hartford, Connecticut. Using a combination of statistical and spatial analysis, we first built a Supermarket Redlining Index (SuRI) from five indicators (sales volume, employee count, accepts food coupons from federally assisted programs, and size and population density of the service area) to rank supermarkets in the order of their importance. Second, to understand the effects of supermarket closures in the inner city, a Supermarket Redlining Impact Model (SuRIM) was built with 11 indicators describing both socioeconomic and food access vulnerabilities. The interaction of these vulnerabilities identified neighborhoods that are maximally impacted by spatial supermarket redlining. Results mapped critical areas in the inner city of Hartford where, if a nearby supermarket closed down or relocated to a suburb with limited mitigation efforts to fill the grocery gap, a large number of minority, poor, and disadvantaged residents would experience difficulties to access healthy food, leading to food insecurity or perhaps a food desert. In conclusion we suggest mitigation efforts to reduce this impact of large supermarket closures.  相似文献   

Prospects of Measuring the Angular Power Spectrum of the Diffuse Galactic Synchrotron Emission with SKA1 Low     

Sk. Saiyad Ali  Somnath Bharadwaj  Samir Choudhuri  Abhik Ghosh  Nirupam Roy 《Journal of Astrophysics and Astronomy》2016,37(4):35

The Diffuse Galactic Syncrotron Emission (DGSE) is the most important diffuse foreground component for future cosmological 21-cm observations. The DGSE is also an important probe of the cosmic ray electron and magnetic field distributions in the turbulent interstellar medium (ISM) of our galaxy. In this paper we briefly review the Tapered Gridded Estimator (TGE) which can be used to quantify the angular power spectrum C _? of the sky signal directly from the visibilities measured in radio-interferometric observations. The salient features of the TGE are: (1) it deals with the gridded data which makes it computationally very fast, (2) it avoids a positive noise bias which normally arises from the system noise inherent to the visibility data, and (3) it allows us to taper the sky response and thereby suppresses the contribution from unsubtracted point sources in the outer parts and the side lobes of the antenna beam pattern. We also summarize earlier work where the TGE was used to measure the C _? of the DGSE using 150 MHz GMRT data. Earlier measurements of C _? are restricted to \(\ell \le \ell _{\max } \sim 10^{3}\) for the DGSE, the signal at the larger ? values is dominated by the residual point sources after source subtraction. The higher sensitivity of the upcoming SKA1 Low will allow the point sources to be subtracted to a fainter level than possible with existing telescopes. We predict that it will be possible to measure the C _? of the DGSE to larger values of \(\ell _{\max }\) with SKA1 Low. Our results show that it should be possible to achieve \(\ell _{\max }\sim 10^{4}\) and ～10⁵ with 2 minutes and 10 hours of observations respectively.  相似文献