Remote Sensing for Martian Studies: Inferences from Syrtis Major     

Vidhya Ganesh Rangarajan  Rishikesh Bharti  Sandeep K. Mondal  C. Pradhan  S. Dutta 《Journal of the Indian Society of Remote Sensing》2018,46(9):1537-1551

Remote sensing techniques have proved to be highly efficient in the exploration of Mars. Availability of several sensors operating across the electromagnetic spectrum on-board orbiters, landers and rovers has helped better understand the surface and atmospheric conditions on the Red planet. This article summarises the application potential of the sensors operating in different wavelength regions for Martian surface studies. Mars unlike Earth allows for utilizing remote sensing techniques in the complete thermal infrared region, owing to narrow absorption regions from a singularly dominant CO₂ atmosphere which facilitate detailed lithological mapping. This work also reviews various methodologies adopted till date to study the lithology, mineralogy and fluvial geomorphology including inferences from Syrtis Major volcanic construct. It is evident from the studies, Syrtis Major has well developed fluvial channels mostly attributed to lava flows. However, spectroscopic studies reveal the presence of hydroxylated and hydrated minerals which indicate that lava might not be the sole factor resulting in channel generation in the construct. Future space missions with high resolution payloads targeting this volcanic construct are indispensable to study these channels in detail.  相似文献   

Changing Pattern of Channel Morphology of Alaknanda River in Srinagar Valley (Garhwal Himalaya), India     

D. D. Chauniyal  Surajit Dutta  Sapna Semwal 《Journal of the Indian Society of Remote Sensing》2018,46(9):1379-1387

The Alaknanda River is the most significant parental river of Ganga and forms an 11.5 km long and 2.5 km wide valley, locally known as the Srinagar Valley. The purpose of the present study is to highlight the recent landform changes in the Alaknanda channel course after the Kedarnath disaster, 2013. The Kedarnath flood completely changed the channel morphology of the Alaknanda river. The river changed its course at Srikot, SSB and Sriyantra Tapu with lower terraces being silted by sands at Ranihat, SSB, Bhaktiyana and Sriyantra Tapu. A new depositional terrace also formed opposite to Sriyantra Tapu. New lateral channel bars, braided channels, back swamp, rapids, pools and river souls were identified in the channel course of the river. Shifting of the channel course at Chauras still remains a serious problem for the Garhwal University Chauras Campus. About 2–5 m silt was deposited on the lower terrace at SSB, and ITI. The Srikot river bed was appended to 4.60 m. Shifting of channel course remains a serious threat to the Srinagar valley. Urbanization, sand and boulders mining, construction of dam, hydrological canal, road and settlements are the prominent example of anthropogenic activities which affect the shifting channel.  相似文献   

Assessing the seismic torsional vulnerability of elevated tanks with RC frame-type staging     

S. C. Dutta  S. K. Jain  C. V. R. Murty 《Soil Dynamics and Earthquake Engineering》2000,19(3):227

Recurrence of torsional failure of elevated water tanks in past earthquakes (including 1952 Kern County and recent 1993 Killari earthquakes) has highlighted the importance of this problem. It is established that these structures may have amplified torsion-induced rotation if their torsional-to-lateral natural period ratio τ is close to 1 and amplified displacement of structural elements due to the coupled lateral-torsional vibration if τ is within the critical range 0.7<τ<1.25. The present study aims to estimate the range of variation of τ for usually constructed reinforced concrete elevated water tanks with frame-type stagings for assessing their torsional vulnerability. Closed-form expressions for torsional and lateral stiffness of tank stagings are derived and verified by standard finite element software. These expressions are used for studying the variation of τ for feasible ranges of influencing parameters. It is seen that a very large number of such tanks may have τ within the said critical range. Closed-form expressions for moments and shear forces of columns and beams under torsion and that under lateral force are also derived. It is also seen with the help of these expressions that the frame stagings of these tanks normally designed for seismic lateral force, may yield through formation of plastic hinges simultaneously in all columns instead of in beams if they are subjected to large rotational response for having τ possibly very close to 1. Such a pattern of yielding generally converts the whole system suddenly into a mechanism causing immediate collapse. Therefore, torsional coupling seems to be a potential cause of failure for these structures.  相似文献   

A rock mass classification model for caving roofs     

A. K. Ghose  D. Dutta 《Geotechnical and Geological Engineering》1987,5(3):257-271

Summary Evaluation of the caving behaviour of longwall roof rocks has thus far been based on a pot-pourri of classification systems, which ignore basic caving criteria. The paper outlines a new classification model of roof strata namely cavability using fuzzy set methodology and linguistic variables to assign ratings for individual roof beds. A microcomputer program has been developed to evaluate the decision ratings for cavability and the model applied to ten longwall case-histories from Indian coalfields. The classification model has excellent potential for being used as a standard tool for the evaluation of caving behaviour of longwall roof rocks.  相似文献   

Unsteady curvilineal flow of an incompressible simple fluid between two rotating concentric spheres     

Jagannath Dutta  T. K. Chaudhury 《Pure and Applied Geophysics》1973,102(1):161-166

Summary Unsteady curvilineal flow of an incompressible simple fluid (based on Noll's theory) representing the flow between two rotating concentric spheres is considered. The outer sphere is assumed to undergo forced harmonic oscillations about a vertical axis through its centre, while the inner sphere is constrained by a torsionwire. It is found that exact solution in terms of Bessels functions exists under certain conditions on the shear stress function and the normal stress functions.  相似文献   

Propagation of Love Waves in a certain type of heterogeneous layer     

Subhas Dutta 《Pure and Applied Geophysics》1971,87(1):124-127

Summary Propagation of Love Waves in a layer in which the velocity first decreases with depth, reaches a miniumm at a certain depth and then increases as the depth further increases in studied in this paper.  相似文献   

Groundwater study in the Piedmont zone of Mechi Mahananda interfluve in Darjiling district,West Bengal using remote sensing techniques     

M. M. Jana  M. Dutta 《Journal of the Indian Society of Remote Sensing》1996,24(1):43-52

The Mechi-Mahananda interfluve is a transitional area between the hills and the plains and exhibits a wide range of topographical variations. The drainage system of the area has a close relationship with lithology and landforms. The rivers originating in the hills attain a braiding character and have well developed alluvial fans. Piedmont plain covers a large area and has high ground water potential. The river terraces and flood plains also have high potentialities of ground water targeting. Fluctuation of water table is very high in the upper piedmont plain dependent upon the proximity to the drainage lines.  相似文献   

Effect of density stratification on love waves     

Subhas Dutta 《Pure and Applied Geophysics》1966,64(1):9-13

Summary The effect on the propagation of love waves in a density stratified crust of finite thickness lying on a homogeneous half space is studied in this paper. Variations of phase and group velocities with wave number are obtained and the result is compared with that ofWilson.  相似文献   

On the propagation of Love waves in a non-homogeneous internal stratum of finite depth lying between two semi-infinite isotropic media     

Subhas Dutta 《Pure and Applied Geophysics》1963,55(1):31-36

Summary The possibility of propagation of Love waves in a non-homogeneous internal stratum of finite depth lying between two semi-infinite isotropic media has been studied in this paper. The density and rigidity of the internal stratum are taken to vary exponentially with depth.  相似文献   

Multiple forecasts of kharif rice in orissa state-four year experience of fasal pilot study     

N. K. Patel  M. Chakraborty  S. Dutta  C. Patnaik  J. S. Parihar  S. C. Moharana  A. Das  B. K. Sarangi  G. Behera 《Journal of the Indian Society of Remote Sensing》2004,32(2):125-143

Considering the requirement of multiple pre-harvest crop forecasts, the concept of Forecasting Agricultural output using Space, Agrometeorology and Land based observations (FASAL) has been formulated. Development of procedure and demonstration of this technique for four in-season forecasts for kharif rice has been carried out as a pilot study in Orissa State since 1998. As the availability of cloud-free optical remote sensing data during kharif season is very poor for Orissa state, multi-date RADARSAT SCANSAR data were used for acreage estimation of kharif rice. Meteorological models have been developed for early assessment of acreage and prediction of yield at mid and late crop growth season. Four in-season forecasts were made during four kharif seasons (1998-2001); the first forecast of zone level rice acreage at the beginning of kharif crop season using meteorological models, second forecast of district level acreage at mid growth season using two-date RADARSAT SCANSAR data and yield using meteorological models, third forecast at late growth season of district level acreage using three-date RADARSAT SCANSAR data and yield using meteorological models and revised forecast incorporating field observations at maturity. The results of multiple forecasts have shown rice acreage estimation and yield prediction with deviation up to 14 and 11 per cent respectively. This study has demonstrated the potential of FASAL concept to provide inseason multiple forecasts using data of remote sensing, meteorology and land based observations.  相似文献