Artificial neural network and liquefaction susceptibility assessment: a case study using the 2001 Bhuj earthquake data,Gujarat, India   总被引：2，自引：0，他引：2  

D. Ramakrishnan  T. N. Singh  N. Purwar  K. S. Barde  Akshay. Gulati  S. Gupta 《Computational Geosciences》2008,12(4):491-501

This study pertains to prediction of liquefaction susceptibility of unconsolidated sediments using artificial neural network (ANN) as a prediction model. The backpropagation neural network was trained, tested, and validated with 23 datasets comprising parameters such as cyclic resistance ratio (CRR), cyclic stress ratio (CSR), liquefaction severity index (LSI), and liquefaction sensitivity index (LSeI). The network was also trained to predict the CRR values from LSI, LSeI, and CSR values. The predicted results were comparable with the field data on CRR and liquefaction severity. Thus, this study indicates the potentiality of the ANN technique in mapping the liquefaction susceptibility of the area.  相似文献   

Resourcesat (IRS-P6) value added data products     

S. M. Moorthi  Nitant Dube  D. Dhar  B. Kartikeyan  R. Ramakrishnan 《Journal of the Indian Society of Remote Sensing》2005,33(2):277-283

Remote sensing data products need to meet stringent geodetic and geometric accuracy specifications irrespective of intended user applications. Georeferencing is the basic processing step towards achieving this goal. Having known the imaging geometry and mechanism, the mathematical models built with the use of orbit and attitude information of the spacecraft can correct the remote sensing data for its geometric degradations only up to system level accuracy (IRS-P6 DP Team, 2000). The uncertainties in the orbit and attitude information will not allow the geometric correction model to generate products of accuracy that can meet user requirements unless Ground Control Points (GCP) are used as reference geo-location landmarks. IRS-P6 data processing team has been entrusted with developing a software system to generate data products that will have desired geodetic and geometric accuracies with known limitations. The intended software system is called the Value Added Data Products System (VADS). Precision corrected, Template Registered, Merged and Ortho Rectified products are the value added products planned with VADS.  相似文献   

An automated seamless mosaicing system of multi-charge coupled devices of panchromatic data     

R. Ramakrishnan  S. Manthira Moorthi  N. Padmanabhan  P. Gupta 《Journal of the Indian Society of Remote Sensing》2004,32(1):103-111

Panchromatic data of pixel resolution 5.8 m obtained from IRS-1C and IRS-1D satellites proved to be very useful for mapping purposes. One of the popular data product is the 70 km swath mosaic which is covered by a combination of 3 CCD line sensors, each with 4096 pixels. Each CCD-line sensor with different imaging times causes geometric problems of mosaicing three strips data together. In this paper, we propose the details of the design elements of system that caters to the need for accurate and automatic multi strip image registration without any second resampling of the data. The systematic geometric correction grid mapping is improved to facilitate accurate mosaicing by automatic image registration task that makes use of the overlap data within image strips and image registration is achieved up to sub-pixel level.  相似文献   

Sustainable Development, Climate Change and Tropical Rain Forest Landscape     

P. S. Ramakrishnan 《Climatic change》1998,39(2-3):583-600

A potential impact of climate change in the south Asian context in general and the Indian subcontinent in particular is an increase in rainfall, in some areas up to 50%. Using an extensive information base available on the dynamics of landscape structure and function of the northeastern hill areas of India, scenarios on landscape changes, as an adaptation to climate change, have been constructed. Climate change would impose a variety of stresses on sustainable livelihood of the inhabitants of the rain-forested areas through stresses on ecosystem function. It is concluded that appropriate management strategies for natural forests and plantation forestry should go hand in hand with a comprehensive rural ecosystem rehabilitation plan.  相似文献   

Response of circular bridge decks to moving vehicles     

R. Ramakrishnan  V. X. Kunukkasseril 《地震工程与结构动力学》1977,5(4):377-394

This paper discusses the dynamic response of a curved bridge deck to a moving vehicle. The bridge deck is idealized as a set of annular sector plates and circular rings rigidly jointed together. On the basis of classical plate and ring theories a method has been developed to obtain the response to a moving vehicle idealized as a spring mass system. After obtaining the normal modes and frequencies and establishing the orthogonality conditions, the problem of the forced motion of the deck is solved by the method of spectral representation. Numerical results have been presented to illustrate the effect of several vehicle and bridge parameters on the response.  相似文献   

Assessment of flexural analysis applied to the Sumatra-Java subduction zone     

R. T. Ratheesh Kumar  Tanmay K. Maji  Rajesh R. Nair 《Journal of Earth System Science》2010,119(5):717-730

Indian Ocean subduction zone is one of the most active plate margins of the globe as evident from its vast record of great magnitude earthquake and tsunami events. We use Bouguer admittance (Morlet isostatic response function) in Sumatra-Java subduction zones comprising both the subduction and over-riding plates to determine the lithospheric mechanical strength variations. We determine effective elastic thickness (T _e ) for five oceanic windows (size 990 × 990 km²) by analyzing the admittance using Bouguer gravity and bathymetry data. The results show bimodal T _e values < 20 km for Sumatra and 20−40 km for Java. The lower bimodal values obtained for Sumatra appears to correlate well with the zones of historical seismicity. This is in sharp contrast with Java subduction zone, which shows higher T _e values (20–40 km) and apparently associated with low magnitude earthquakes. We suggest a strong and wide interseismic coupling for Sumatra between the subducting and over-riding plates, and deeper mantle contributing to low strength, shallow focus — high magnitude seismicity and vice versa for Java, leading to their seismogenic zonation.  相似文献   

Shoreline Change Analysis along the Coast of South Gujarat,India, Using Digital Shoreline Analysis System   总被引：1，自引：0，他引：1  

Manik Mahapatra  R. Ratheesh  A. S Rajawat 《Journal of the Indian Society of Remote Sensing》2014,42(4):869-876

Shoreline changes along the south Gujarat coast has been analyzed by using USGS Digital Shoreline Analysis System (DSAS) version 4.3. Multi-temporal satellite images pertaining to 1972, 1990, 2001 and 2011 were used to extract the shoreline. The High water line (HTL) is considered as shoreline and visual interpretation of satellite imageries has been carried out to demarcate the HTL based on various geomorphology and land use & land cover features. The present study used the Linear Regression Method (LRR) to calculate shoreline change rate. Based on the rate of shoreline changes, the coastal stretches of study area has been classified in to high erosion, low erosion, stable, low accretion and high accretion coast. The study found that about 69.31 % of the South Gujarat coast is eroding, about 18.40 % of coast is stable and remaining 12.28 % of the coast is accreting in nature. Field investigation was carried out which confirmed the coastal erosion/accretion derived from the analysis. The high erosion area are mostly found along the Umergaon (near Fansa, Maroli, Nargol, Varili river mouth, Umergaon light house) and Pardi (Kolak, Udwara)Taluka in Valsad district. Stable coastal length of the study area is 21.59 km and mostly found in Nani Dandi and near Onjal. High accretion (3.70 %) was only found near Hajira and low accretion (8.58 %) are distributed the study area. The main causes of coastal erosion of the study area were the strong tidal currents accompanied by wave action and reduced the sediment load of the river.  相似文献   

An interpretation of wave refraction and its influence on foreshore sediment distribution     

Joevivek Vincent Jayaraj  Chandrasekar Nainarpandian  Jayangondaperumal Ramakrishnan  Thakur Vikram Chandr  Shree Purniema Krishnan 《海洋学报(英文版)》2019,38(5):151-160

To analyze the grain size and depositional environment of the foreshore sediments, a study was undertaken on wave refraction along the wide sandy beaches of central Tamil Nadu coast. The nearshore waves approach the coast at 45° during the northeast(NE) monsoon, at 135° during the southwest(SW) monsoon and at 90° during the non-monsoon or fair-weather period with a predominant wave period of 8 and 10 s. A computer based wave refraction pattern is constructed to evaluate the trajectories of shoreward propagating waves along the coast in different seasons. The convergent wave rays during NE monsoon, leads to high energy wave condition which conveys a continuous erosion at foreshore region while divergent and inept condition of rays during the SW and non-monsoon, leads to moderate and less energy waves that clearly demarcates the rebuilt beach sediments through littoral sediment transport. The role of wave refraction in foreshore deposits was understood by grain size and depositional environment analysis. The presence of fine grains with the mixed population, during the NE monsoon reveals that the high energy wave condition and sediments were derived from beach and river environment. Conversely, the presence of medium grains with uniform population, during SW and non-monsoon attested less turbulence and sediments were derived from prolong propagation of onshore-offshore wave process.These upshots are apparently correlated with the in situ beach condition. On the whole, from this study it is understood that beaches underwent erosion during the NE monsoon and restored its original condition during the SW and non-monsoon seasons that exposed the stability of the beach and nearshore condition.  相似文献   

An early warning system for inundation forecast due to a tropical cyclone along the east coast of India     

Mandal  Anup Kumar  Ramakrishnan  Ratheesh  Pandey  Smita  Rao  A. D.  Kumar  Prashant 《Natural Hazards》2020,103(2):2277-2293

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Impact of SARAL/AltiKa-Derived Sea Level Anomaly in a Data Assimilative Ocean Prediction System for the Indian Ocean     

Smitha Ratheesh  Rashmi Sharma  K. V. S. R. Prasad  Sujit Basu 《Marine Geodesy》2015,38(3):354-364

The impact of SARAL/AltiKa derived sea level anomaly (SLA) has been studied by assimilating it along with Jason-2 and Cryosat-2 SLA in the Princeton Ocean model (POM) using ensemble optimal interpolation (EnOI) technique. For isolating the extra benefit brought by SARAKL/Altika, a parallel run with assimilation of only Jason-2 and Cryosat-2 SLA has also been conducted. The importance of SARAL SLA in a data assimilative ocean prediction system has been evaluated with special emphasis on the improvement in thermocline depth, depth of the 20° isotherm, subsurface temperature and currents. Comparison with RAMA buoy has shown a positive impact of up to 13% for 20°C isotherm and up to 17% for thermocline depth after assimilating SARAL SLA. An overall improvement in temperature profile is also observed when compared with analogous profiles from RAMA buoys and Argo floats. Improvement in zonal currents away from the equator has also been noticed.  相似文献