Image and non-image parameters of atmospheric Cherenkov events: a comparative study of their γ-ray/hadron classification potential in ultrahigh energy regime     

A. Razdan  A. Haungs  H. Rebel  C. L. Bhat 《Astroparticle Physics》2002,17(4):2735-508

In this exploratory simulation study, we compare the event-progenitor classification potential of a variety of measurable parameters of atmospheric Cherenkov pulses which are produced by ultrahigh energy γ-ray and hadron progenitors and are likely to be recorded by the TACTIC (TeV atmospheric Cherenkov telescope with imaging camera) array of atmospheric Cherenkov telescopes. The parameters derived from Cherenkov images include Hillas, fractal and wavelet moments, while those obtained from non-image Cherenkov data consist of pulse profile rise time and base width and the relative ultraviolet to visible light content of the Cherenkov event. It is shown by a neural-net approach that these parameters, when used in suitable combinations, can bring about a proper segregation of the two event types, even with modest sized data samples of progenitor particles.  相似文献   

On the measurement of the surface energy budget over a land surface during the summer monsoon     

G. S. Bhat  S. C. Arunchandra 《Journal of Earth System Science》2008,117(6):911-923

The measurement of surface energy balance over a land surface in an open area in Bangalore is reported. Measurements of all variables needed to calculate the surface energy balance on time scales longer than a week are made. Components of radiative fluxes are measured while sensible and latent heat fluxes are based on the bulk method using measurements made at two levels on a micrometeorological tower of 10m height. The bulk flux formulation is verified by comparing its fluxes with direct fluxes using sonic anemometer data sampled at 10Hz. Soil temperature is measured at 4 depths. Data have been continuously collected for over 6 months covering pre-monsoon and monsoon periods during the year 2006. The study first addresses the issue of getting the fluxes accurately. It is shown that water vapour measurements are the most crucial. A bias of 0.25% in relative humidity, which is well above the normal accuracy assumed by the manufacturers but achievable in the field using a combination of laboratory calibration and field intercomparisons, results in about 20W m⁻² change in the latent heat flux on the seasonal time scale. When seen on the seasonal time scale, the net longwave radiation is the largest energy loss term at the experimental site. The seasonal variation in the energy sink term is small compared to that in the energy source term.  相似文献   

Farmer-level adaptation to climate change and agricultural drought: empirical evidences from the Barind region of Bangladesh     

Md. Nazir Hossain  Swapna Chowdhury  Shitangsu Kumar Paul 《Natural Hazards》2016,83(2):1007-1026

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Rhenium (Re)–Osmium (Os) geochronology of the Proterozoic Sirban Limestone Formation,NW Himalaya     

Naveen Hakhoo  Bindra Thusu  Ghulam M. Bhat  Jonathan Craig  Juergen Thurow  Mateen Hafiz 《Journal of the Geological Society of India》2016,88(3):267-272

The Proterozoic Sirban Limestone Formation (SLFm) exposed in a number of inliers in Jammu (India), NW Himalaya is a potential target for hydrocarbon and ore mineral exploration. The structural complexity not only makes correlation of the SLFm with coeval hydrocarbon producing Proterozoic formations in the neighbouring Salt Range in Pakistan and elsewhere in the world extremely difficult, but also limits the understanding of the genesis of sedimentary hosted mineral deposits. The base of the SLFm inliers is not exposed anywhere in the region and the age of this sequence has been suggested to range from Palaeoproterozoic to Neoproterozoic.  相似文献   

Remote Sensing and GIS based groundwater potential mapping for sustainable water resource management of Lidder catchment in Kashmir Valley,India     

Mohammad Imran Malik  M. Sultan Bhat  Shahnaz Ahmad Najar 《Journal of the Geological Society of India》2016,87(6):716-726

The valley of Kashmir is blessed with abundant water resources. However, high population growth and concentration of population at favorable locations have resulted in increased demand for water. The problem is further aggravated in Lidder catchment where unplanned tourism development has resulted in deterioration of water quality. Multi-Criteria Evaluation (MCE) approach is adopted using IRS P6 LISS III satellite data 2010, geological map published by Geological Survey of India, toposheets prepared by Survey of India, 1961 and field observation. Seven thematic layers (slope, lineament density, drainage density, soil, geology, geomorphology and land use land cover) are generated in GIS environment and weighted according to their relative relevance to groundwater occurrence. Knowledge-based weights and ranks are normalized, and a weighted linear combination technique is adopted to determine the groundwater potential (GWP). The catchment is divided into five zones of very high, high, medium, low and very low GWP. The results show that 50.22% of the total catchment area, which is uninhabited, has very low GWP. However, the densely populated southern part of the catchment has moderate to very high GWP. The study demonstrates that MCE using remote sensing and GIS technology could be efficiently employed as a very useful tool for the assessment and management of groundwater resources especially in regions where data is poor.  相似文献   

Petrographical and geochemical signatures of Jurassic rocks of Chari Formation,Western India: implications for provenance and tectonic setting     

Shaista Khan  A. H. M. Ahmad  M. Masroor Alam  Adnan Quasim 《中国地球化学学报》2016,35(2):184-202

The sandstones of the Ridge and Athleta members of Chari Formation (Callovian-Oxfordian) exposed at Jara have been analyzed for their petrographical and geochemical studies. Texturally, these sandstones are medium to coarse grained, poorly to well sorted, sub-angular to sub-rounded, and show low to medium sphericity. These sandstones were derived from a mixed provenance including granites, granite-gneisses, low and high-grade metamorphic, and some basic rocks of Aravalli range and Nagarparkar massif. The petrofacies analysis reveals that these sandstones belong to the continental block and recycled orogen tectonic regime. The studied sandstones are modified by paleoclimate, distance of transport, and diagenesis. Mineralogically and geochemically, sandstones are classified as quartzarenite, subarkose, arkose, sublithic arenite, and wacke, respectively. The A-CN-K ternary plot and CIA, CIW, PIA, and ICV values suggest that the similar source rocks suffered moderate to high chemical weathering under a hot-humid climate in an acidic environment with higher \({\text{P}}_{{{\text{CO}}_{ 2} }}\). Generally good to strong correlations between Al₂O₃ and other oxides in these sediments indicate clay mineral control. The K₂O/Na₂O versus SiO₂ diagram indicates that the studied samples occupy passive margin fields but the SiO₂/Al₂O₃ versus K₂O/Na₂O plot suggests that the Athleta Sandstone and Ridge Sandstone fall within the passive margin field, while Ridge Shale falls within the active continental margin field.  相似文献   

Spatiotemporal trends of temperature extremes in Bangladesh under changing climate using multi-statistical techniques     

Mallick  Javed  Islam  Abu Reza Md. Towfiqul  Ghose  Bonosri  Islam  H. M. Touhidul  Rana  Yousuf  Hu  Zhenghua  Bhat  Shakeel Ahmed  Pal  Subodh Chandra  Ismail  Zulhilmi Bin 《Theoretical and Applied Climatology》2022,147(1-2):307-324

Theoretical and Applied Climatology - The rise in the frequency and magnitude of extreme temperature phenomena across the globe has led to the recurrent incidence of global climate hazards, which...  相似文献   

Paleoseismological investigations along Joggers Park Fault,Port Blair,South Andaman: Implications towards delineation of blind thrusting and related crustal deformation through ground penetrating radar (GPR) and electrical resistivity techniques (ERT and VES)     

Gulam Rasool Bhat  S. Balaji  Bikram S. Bali  Vazeem Iqbal  Balakrishna  Hamid Hussain 《Journal of the Geological Society of India》2018,91(1):81-90

A comprehensive paleoseismological investigations was carried out along Joggers Park Fault (striking NW-SE) reveals pervasive traces of active compressional tectonics (blind thrusting) and shallow-surface recent tectonic signatures along the fault. The geometry and trends in the tectonic deformation of the blind zone (shallow-subsurface stratigraphy) were examined with GPR and electrical resistivity tomography (ERT) and vertical electrical sounding (VES), strongly demonstrates severe tectonic deformation (persistent tectonic style) from Quaternary to Holocene times in a compressive stress regime. The surface manifestation of deformation (topographic expression) along the fault can be marked as hanging wall uplift and can be visually observed in the exposed sections at nearly half kilometer distance from the table land of Joggers Park in the form of a well-defined disconnected high angle thrust fault scarp (reverse fault). The reverse fault kinematically and intimately linked with underlying fault geometry provides adduced evidence to evaluate strike displacement profiles (displacement length relationship) along the fault. In addition, deformed stacked colluvial wedge below the scarp represents a powerful basis to calibrate recent and long term slip rates of the underlying fault.  相似文献   

Ground-based calibration and characterization of the Fermi gamma-ray burst monitor detectors     

E. Bissaldi  A. von Kienlin  G. Lichti  H. Steinle  P. N. Bhat  M. S. Briggs  G. J. Fishman  A. S. Hoover  R. M. Kippen  M. Krumrey  M. Gerlach  V. Connaughton  R. Diehl  J. Greiner  A. J. van der Horst  C. Kouveliotou  S. McBreen  C. A. Meegan  W. S. Paciesas  R. D. Preece  C. A. Wilson-Hodge 《Experimental Astronomy》2009,24(1-3):47-88

One of the scientific objectives of NASA’s Fermi Gamma-ray Space Telescope is the study of Gamma-Ray Bursts (GRBs). The Fermi Gamma-Ray Burst Monitor (GBM) was designed to detect and localize bursts for the Fermi mission. By means of an array of 12 NaI(Tl) (8 keV to 1 MeV) and two BGO (0.2 to 40 MeV) scintillation detectors, GBM extends the energy range (20 MeV to > 300 GeV) of Fermi’s main instrument, the Large Area Telescope, into the traditional range of current GRB databases. The physical detector response of the GBM instrument to GRBs is determined with the help of Monte Carlo simulations, which are supported and verified by on-ground individual detector calibration measurements. We present the principal instrument properties, which have been determined as a function of energy and angle, including the channel-energy relation, the energy resolution, the effective area and the spatial homogeneity.  相似文献   

Drive-Control System for the TACTIC Gamma-Ray Telescope     

A. K. Tickoo  R. Koul  S. K. Kaul  I. K. Kaul  C. L. Bhat  N. G. Bhatt  M. K. Kothari  H. C. Goyal  N. K. Agarwal  S. R. Kaul 《Experimental Astronomy》1999,9(2):81-101

A PC-based drive-control system has been developed for the altitude-azimuth mounted TACTIC -ray telescope to control the speed and direction of motion of its 2-axes. Details of various hardware components chosen for the telescope, including hybrid-stepper motor, 16-bit absolute encoder and CAMAC-based programmable stepper motor controller, are discussed in this paper. The telescope-control strategy, based on the position-loop with a proportional type control for the source-seek mode and the on/off type control for the tracking mode, is explained in detail. Some important performance features of the telescope, including its blind-spot size, drive-system backlash and encoder-error compensation, are also presented. The drive system has been extensively field-tested and has been operating satisfactorily during observation campaigns carried out since March 1997 with the TACTIC Imaging Element. A tracking accuracy of ±3 arc-minutes has been achieved. A test report of its performance, with regard to its tracking accuracy on the basis of successful detection of TeV -rays from the active galaxy Markarian 501 in April–May 1997, is also presented.  相似文献