Gamma/hadron segregation for a ground based imaging atmospheric Cherenkov telescope using machine learning methods: Random Forest leads     

Mradul Sharma  Jitadeepa Nayak  Maharaj Krishna Koul  Smarajit Bose  Abhas Mitra 《中国天文和天体物理学报》2014,(11)

A detailed case study of γ-hadron segregation for a ground based atmospheric Cherenkov telescope is presented. We have evaluated and compared various supervised machine learning methods such as the Random Forest method, Artificial Neural Network, Linear Discriminant method, Naive Bayes Classifiers, Support Vector Machines as well as the conventional dynamic supercut method by simulating triggering events with the Monte Carlo method and applied the results to a Cherenkov telescope. It is demonstrated that the Random Forest method is the most sensitive machine learning method for γ-hadron segregation.  相似文献   

THE PATORA METEORITE,AN H6 FALL     

A. L. Graham  V. K. Nayak 《Meteoritics & planetary science》1974,9(2):137-139

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Models for estimating evapotranspiration using artificial neural networks,and their physical interpretation     

S. K. Jain  P. C. Nayak  K. P. Sudheer 《水文研究》2008,22(13):2225-2234

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Fuzzy model identification based on cluster estimation for reservoir inflow forecasting     

P. C. Nayak  K. P. Sudheer 《水文研究》2008,22(6):827-841

Fuzzy theory appears to be extremely effective at handling dynamic, non‐linear and noisy data, especially when the underlying physical relationships are not fully understood. Since hydrologists are still uncertain about many of the aspects of the physical processes in the watershed, fuzzy theory has proved to be a very attractive tool enabling them to investigate such problems. The effectiveness of the fuzzy model lies in the identification of the antecedent membership function (MF), which is generally addressed through a fuzzy clustering approach. Most of the applications of fuzzy computing in hydrology seem to have selected the clustering algorithm quite arbitrarily. However, it is apparent that, as the antecedent parameters are based solely on the identified clusters, the method used for clustering should certainly have an impact on the overall performance of the model. This paper presents the results of a study conducted to investigate the impact of choice of clustering algorithm on the overall performance of a fuzzy‐based hydrologic model. The research is illustrated through a case study of developing a Takagi–Sugeno fuzzy model for reservoir inflow forecasting in the Narmada basin, India. The model was developed using two popular clustering techniques, namely Gustafson–Kessel (GK) and subtractive clustering (SC), and was extensively evaluated for performance based on various statistical indices. The results show that the model performance is comparable at a 1 h lead forecast. However, it is observed that the GK approach results in a better performance than the SC approach in computing forecasts at higher lead times. The analysis suggest that the GK method clusters the input space based on the actual pattern, since it uses a membership‐grade weighted‐distance measure as the measure of closeness, whereas the SC method classifies the input space more logically according to the magnitude of flow available in the data set. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

String fluid cosmological models in general relativity     

S. K. Tripathy  S. K. Nayak  S. K. Sahu  T. R. Routray 《Astrophysics and Space Science》2008,318(1-2):125-131

LRS Bianchi type-I string cosmological models are studied in the frame work of general relativity when the source for the energy momentum tensor is a bulk viscous fluid containing one dimensional strings embedded in electromagnetic field. A barotropic equation of state for the pressure and density is assumed to get determinate solutions of the field equations. The bulk viscosity is assumed to be inversely proportional to the scalar expansion. The physical and kinematical properties of the models are discussed. The effect of viscosity and electromagnetic field on the physical and kinematical properties is also investigated.  相似文献   

Groundwater arsenic contamination and its health effects in India   总被引：2，自引：0，他引：2  

Dipankar Chakraborti  Mohammad Mahmudur Rahman  Bhaskar Das  Amit Chatterjee  Dipankar Das  Biswajit Nayak  Arup Pal  Uttam Kumar Chowdhury  Sad Ahmed  Bhajan Kumar Biswas  Mrinal Kumar Sengupta  Md. Amir Hossain  Gautam Samanta  M. M. Roy  Rathindra Nath Dutta  Khitish Chandra Saha  Subhas Chandra Mukherjee  Shyamapada Pati  Probir Bijoy Kar  Adreesh Mukherjee  Manoj Kumar 《Hydrogeology Journal》2017,25(4):1165-1181

During a 28-year field survey in India (1988–2016), groundwater arsenic contamination and its health effects were registered in the states of West Bengal, Jharkhand, Bihar and Uttar Pradesh in the Ganga River flood plain, and the states of Assam and Manipur in the flood plain of Brahamaputra and Imphal rivers. Groundwater of Rajnandgaon village in Chhattisgarh state, which is not in a flood plain, is also arsenic contaminated. More than 170,000 tubewell water samples from the affected states were analyzed and half of the samples had arsenic >10 μg/L (maximum concentration 3,700 μg/L). Chronic exposure to arsenic through drinking water causes various health problems, like dermal, neurological, reproductive and pregnancy effects, cardiovascular effects, diabetes mellitus, diseases of the respiratory and gastrointestinal systems, and cancers, typically involving the skin, lungs, liver, bladder, etc. About 4.5% of the 8,000 children from arsenic-affected villages of affected states were registered with mild to moderate arsenical skin lesions. In the preliminary survey, more than 10,000 patients were registered with different types of arsenic-related signs and symptoms, out of more than 100,000 people screened from affected states. Elevated levels of arsenic were also found in biological samples (urine, hair, nails) of the people living in affected states. The study reveals that the population who had severe arsenical skin lesions may suffer from multiple Bowens/cancers in the long term. Some unusual symptoms, such as burning sensation, skin itching and watering of eyes in the presence of sun light, were also noticed in arsenicosis patients.  相似文献   

Zoning and monitoring dominant mangrove communities of a part of The Marine National Park, Gulf of Kachchh     

D. G. Shah  Anjali Bahuguna  B. Deshmukh  S. R. Nayak  H. S. Singh  B. H. Patel 《Journal of the Indian Society of Remote Sensing》2005,33(1):155-163

Mangroves of the Marine National Park constitute the second largest patch of mangroves in Gujarat, extending up to 11,000 ha, comprising six species of mangroves. Earlier studies carried out using remote sensing data pertained to baseline data generation and mapping and monitoring the mangroves (density-wise) of the Park from 1975 to 1993. Using IRS IC/ID LISS III data (1998–2001) supported by ground data, the distribution of different mangrove communities in the Park has been attempted. Amongst various image-processing techniques, band ratioing followed by supervised classification gave the best result (classification accuracy was 92%).Avicennia community is the most dominant community accounting for more than 70% of the area. TheRhizophora community occupies the inward margins of the creeks and theCeriops community is present in the interior regions. The ecotone between the marsh and mangrove communities has been identified as the transitional mangroves (Avicennia alba, Sueada), representing the transition from the less saline mangrove to the highly saline marsh community. The zoning of the mangroves has also helped in assessing the diversity of the region. Based on the richness of species, three areas, namely Bhains Bid, North-east Dide Ka Bet and South-east Chhad Island have been identified as highly diverse (most suitable area for preservation).  相似文献   

Composite image of chlorophyll and sea surface temperature (SST) using MODIS-AQUA     

Prakash Chauhan  P. V. Nagamani  H. U. Solanki  Shailesh Nayak 《Journal of the Indian Society of Remote Sensing》2005,33(2):177-180

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Eco-Geomorphological zonation of The Bangaram Reef, Lakshadweep   总被引：1，自引：0，他引：1  

Benidhar Deshmukh  Anjali Bahuguna  Shailesh Nayak  V. K. Dhargalkar  T. G. Jagtap 《Journal of the Indian Society of Remote Sensing》2005,33(1):99-106

Coral reefs, which are known for rich biological diversity and productivity, are being threatened throughout the world by various natural and anthropogenic activities. The present study concentrates on establishing methodology to zone the geo-morphological and ecological zones of the Bangaram reef (of atoll type), Lakshadweep islands, using remotely sensed data and adequately supported by field data. Classification system has been evolved to zone the reefs. Comparative studies have also been carried out using image processing techniques in order to establish the suitable technique for studying the Indian reefs. The IRS LISS III images representing three different tidal conditions of the period 1998-2000 were analyzed. The unsupervised classification of both the raw images as well as principal component images gave similar information. The classified product was subjected to contextual editing. Misclassification among various classes was found to increase with the increase in the depth of the water column present over the reef. The zones identified on the image are central deep lagoon, reef knolls (rising steeply from the central deep lagoon floor), reef edge, reef platform, coralline shelf, broad shallow sandy-bottomed lagoon, beach and two islets. The zonation has helped in getting information on the presence of live corals on the Bangaram reef. This kind of study is a valuable input in assessing the health of the reefs and its diversity.  相似文献   

Hydrogeomorphic studies in Banaskantha and Mehsana districts (Gujarat) using Landsat data     

M. V. Muley  S. R. Nayak 《Journal of the Indian Society of Remote Sensing》1983,11(2):47-52

A hydrogeomorphic approach is used in analyzing hydrologic conditions in the Mehsana and Banaskantha districts of Gujarat state. Using Landsat images, it was possible to delineate geological units, hydrogeomorphic features and vegetation density levels on a regional scale. A relationship between hydrogeomorphic features and vegetation density levels along with ground based hydrologic data was established in Mehsana district and the same was extended to the adjoining Banaskantha district. The ground water potential areas identified were from alluvium and piedmont zone. On the basis of different vegetation density levels, these areas were further subdivided into three different potential zones as regards the availability of groundwater viz. good, fair and poor. The applicability of the remotely sensed data has been found quite useful in quick identification of regional hydrogeomorphic setting of the area.  相似文献