Some rain rate and rain attenuation statistics at millimeter wavelengths in the tropics     

N. C. Mondal  A. B. Bhattacharya  S. K. Sarkar  R. Bhattacharya  A. K. Sen 《Theoretical and Applied Climatology》1996,54(3-4):229-234

Summary A study of rain rate and rain induced attenuation characteristics over two tropical stations in India has been made. The observed rain rate distributions differ significantly when compared with the CCIR report. The refractive indices have been calculated for certain frequencies at a tropical rain temperature of 20°C showing the variational pattern at different millimeter wavelengths. The present analysis also reveals that in the range 0.05 cm–0.3 cm drop diameter the variations of scattering amplitudes are systematic while in the range 0.4 cm–0.6 cm they are irregular.With 6 Figures  相似文献   

Anomalous enhancement in daytime 40-kHz signal amplitude accompanied by geomagnetic storms,earthquakes and meteor showers     

B. K. De  S. K. Sarkar 《Annales Geophysicae》1995,13(10):1117-1123

Anomalous propagational characteristics, daytime signal levels greater than night-time, were observed. The amplitude records of a 40-kHz signal propagated over a distance of 5100 km from Sanwa, Japan to Calcutta along a low-latitude path show higher signal strength at midday compared to the midnight level on days preceded by principal geomagnetic storms, earthquakes and major meteor showers. This is explained by the increased ionization in the D-region following geophysical events. The storm after-effects only have a duration of a single day in this low-latitude path.  相似文献   

Critical earthquake input power spectral density function models for engineering structures     

C. S. Manohar  Abhijit Sarkar 《地震工程与结构动力学》1995,24(12):1549-1566

The problem of determining optimal power spectral density models for earthquake excitation which satisfy constraints on total average power, zero crossing rate and which produce the highest response variance in a given linear system is considered. The solution to this problem is obtained using linear programming methods. The resulting solutions are shown to display a highly deterministic structure and, therefore, fail to capture the stochastic nature of the input. A modification to the definition of critical excitation is proposed which takes into account the entropy rate as a measure of uncertainty in the earthquake loads. The resulting problem is solved using calculus of variations and also within linear programming framework. Illustrative examples on specifying seismic inputs for a nuclear power plant and a tall earth dam are considered and the resulting solutions are shown to be realistic.  相似文献   

Big data and remote sensing for multi-decadal drought impact assessment on Shorea robusta     

Chakraborty  Tanmoy  Sarkar  Showmitra Kumar  Morshed  Md. Manjur 《Theoretical and Applied Climatology》2022,148(3-4):1587-1602

Theoretical and Applied Climatology - Intense droughts in recent years are a global concern. The duration and timing of drought for forests have not been researched as much as crops. This study...  相似文献   

Study of Strain Rate and Thermal Damage of Dholpur Sandstone at Elevated Temperature   总被引：1，自引：0，他引：1  

P. K. Gautam  A. K. Verma  M. K. Jha  K. Sarkar  T. N. Singh  R. K. Bajpai 《Rock Mechanics and Rock Engineering》2016,49(9):3805-3815

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The assessment of slope stability along NH-22 in Rampur-Jhakri Area,Himachal Pradesh     

Kripamoy Sarkar  Ashok Kumar Singh  Anurag Niyogi  Prasanta Kumar Behera  A. K. Verma  T. N. Singh 《Journal of the Geological Society of India》2016,88(3):387-393

The present paper demonstrates the assessment of slope stability analysis between Rampur to Jhakri road section along National Highway (NH-22), Himachal Pradesh, India. The different types of slope failures have affected most part of slopes which causes considerable loss of life and property, inconveniences such as disruption of traffic along highways. The poorly designed rock slopes for road widening or construction purposes may weaken the stability of the slopes. A detail field investigation has been carried out to collect the representative rock samples for determination of physico-mechanical properties of rock and joint data for kinematic analysis. The rocks exposed in the area are highly jointed quartzite and quartz-mica schist of Rampur-Larji Group of Palaeoproterozoic age. The continuous slope mass rating (CSMR) technique has been applied for the assessment of slope stability analysis at five vulnerable locations and the results shows slopes are partially stable to unstable. Kinematic analysis mainly shows wedge type of failure along with few toppling and planar failures. The existing slope required immediate treatment to prevent the failure for its long term stability.  相似文献   

Rock slope analysis along NH-44 in Sonapur Area,Jaintia Hills District,Meghalaya     

Kripamoy Sarkar 《Journal of the Geological Society of India》2016,88(1):121-122

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Evaluation of Spatio-temporal Changes in Surface Water Quality and Their Suitability for Designated Uses,Mettur Reservoir,India     

Saha  Ajoy  Ramya  V. L.  Jesna  P. K.  Mol  S. Sibina  Panikkar  Preetha  Vijaykumar  M. E.  Sarkar  U. K.  Das  B. K. 《Natural Resources Research》2021,30(2):1367-1394

Natural Resources Research - Freshwater has a significant role in determining the ecological environment, public health and socio-economic development. This study analyzed the spatio-temporal...  相似文献   

A simulation of earthquake induced undrained pore pressure changes with bearing on some soil liquefaction observations following the 2001 Bhuj earthquake     

Sarkar  Irene  Chander  Ramesh 《Journal of Earth System Science》2003,112(3):471-477

The Bhuj earthquake of January 26th, 2001, induced wide spread liquefaction within the Kachch peninsula. It has been pointed out that inundation due to soil liquefaction was short lived in some parts than in others in the affected region. Several geological, seismological and hydrological factors would have cumulatively contributed to these observed changes. We simulate in this article, undrained or short-term change in pore pressure in a poroelastic half space, in response to a simplified model of the Bhuj earthquake source. We find that the regions of relatively shorter lived inundation due to soil liquefaction may fall in the region where pore pressure responsible for soil liquefaction attributable to strong ground shaking was counteracted by pore pressure changes due to undrained poroelastic effect and vice versa.  相似文献   

Some studies on Hα-flares and microwave bursts in relation to sunspot magnetic configurations     

M. K. Das Gupta  T. Chattopadhyay  S. K. Sarkar 《Solar physics》1977,51(2):409-412

Sunspot associated H-flares and microwave bursts occurring during the period 1972 to 1974 have been examined in relation to the magnetic strength and configurations of the sunspots and sunspot groups (abbreviated as spots). Important results obtained are: (i) percentage occurrences of flares exceeds those of microwave bursts up to a magnetic field strength of 2000 G while the reverse is true for higher field strength of spots, (ii) flare productivity (average number of flares per spot) and also burst productivity are comparatively higher in the case of and types of spots than in the case of other types of spots, (iii) the above productivities are predominantly high when magnetic configuration of spots changes during their life time, and (iv) impulsive type of microwave bursts are more associated with spots having changing type of magnetic configuration.  相似文献