Spatial distribution of scatterers in the crust by inversion analysis of coda envelopes: a case study of Gauribidanur seismic array (Southern India)     

A. Ugalde  E. Carcolé  J. N. Tripathi 《Geophysical Journal International》2006,166(2):782-794

  相似文献   

On selection of kernel parametes in relevance vector machines for hydrologic applications     

Shivam Tripathi  Rao S. Govindaraju 《Stochastic Environmental Research and Risk Assessment (SERRA)》2007,21(6):747-764

Recent advances in statistical learning theory have yielded tools that are improving our capabilities for analyzing large and complex datasets. Among such tools, relevance vector machines (RVMs) are finding increasing applications in hydrology because of (1) their excellent generalization properties, and (2) the probabilistic interpretation associated with this technique that yields prediction uncertainty. RVMs combine the strengths of kernel-based methods and Bayesian theory to establish relationships between a set of input vectors and a desired output. However, a bias–variance analysis of RVM estimates revealed that a careful selection of kernel parameters is of paramount importance for achieving good performance from RVMs. In this study, several analytic methods are presented for selection of kernel parameters. These methods rely on structural properties of the data rather than expensive re-sampling approaches commonly used in RVM applications. An analytical expression for prediction risk in leave-one-out cross validation is derived. For brevity, the effectiveness of the proposed methods is assessed first by data generated from the benchmark sinc function, followed by an example involving estimation of hydraulic conductivity values over a field based on observations. It is shown that a straightforward maximization of likelihood function can lead to misleading results. The proposed methods are found to yield robust estimates of parameters for kernel functions.  相似文献   

Correction to: Hydro-meteorological and agricultural trends in water-scarce Karha Basin,western India: current and future scenario     

Rahul S. Todmal  Mahendra S. Korade  Amit G. Dhorde  Rajendra B. Zolekar 《Arabian Journal of Geosciences》2018,11(12):317

  相似文献   

Mapping of Marine Chl-a and Suspended Solid Concentration Using OCM-2 Sensor     

S. Kasi Viswanath  N. K. Tripathi  K. R. Salin 《Journal of the Indian Society of Remote Sensing》2018,46(4):675-685

Chlorophyll-a (Chl-a) and Suspended Solid Concentration (SSC) shows the productivity of water and their surrounding environment. These parameters can be effectively estimated through several remote sensing techniques. From the recent reports on the Gulf of Thailand, it is found that Chl-a and SSC are increasing in coastal areas due to changing environment caused by variations in the global carbon cycle, climate change and water pollution linking to anthropogenic conditions such as high population density and rapid urbanization in neighbouring coastal areas deteriorating the coastal and marine environment. Various models are evaluated in this study for estimation of marine Chl-a and SSC by employing Ocean Colour Monitor-2 sensor of Oceansat-2 satellite for Northern Gulf of Thailand. The retrieval of Chl-a and SSC by the atmospheric correction of visible bands from 400 to 700 nm to attain normalized water-leaving radiances and then a suitable algorithm is applied. The In-situ reflectance values of sea waters are measured using the ASD spectroradiometer. The reflectance values of the spectroradiometer are correlated for the same day atmospherically corrected satellite reflectance and the analysis offers high correlation R² 0.73. Satellite derived, Chl-a and SSC are correlated with observed in situ Chl-a and SSC. This analysis offered better correlation of R² 0.86 and 0.85 respectively with the algorithms of Chl-a and SSC.  相似文献   

Genesis and simultaneous occurrences of the super cyclone Kyarr and extremely severe cyclone Maha in the Arabian Sea in October 2019     

Akhila  R. S.  Kuttippurath  J.  Rahul  R.  Chakraborty  A. 《Natural Hazards》2022,110(2):1133-1152

Natural Hazards - Waterlogging and sunlight shortage are important factors that significantly deteriorate the yield and quality of wheat. The objective of this study was to evaluate the effects of...  相似文献   

Impact of LULC change on the runoff,base flow and evapotranspiration dynamics in eastern Indian river basins during 1985–2005 using variable infiltration capacity approach     

Pulakesh Das  Mukunda Dev Behera  Nitesh Patidar  Bhabagrahi Sahoo  Poonam Tripathi  Priti Ranjan Behera  S K Srivastava  Partha Sarathi Roy  Praveen Thakur  S P Agrawal  Y V N Krishnamurthy 《Journal of Earth System Science》2018,127(2):19

As a catchment phenomenon, land use and land cover change (LULCC) has a great role in influencing the hydrological cycle. In this study, decadal LULC maps of 1985, 1995, 2005 and predicted-2025 of the Subarnarekha, Brahmani, Baitarani, Mahanadi and Nagavali River basins of eastern India were analyzed in the framework of the variable infiltration capacity (VIC) macro scale hydrologic model to estimate their relative consequences. The model simulation showed a decrease in ET with 0.0276% during 1985–1995, but a slight increase with 0.0097% during 1995–2005. Conversely, runoff and base flow showed an overall increasing trend with 0.0319 and 0.0041% respectively during 1985–1995. In response to the predicted LULC in 2025, the VIC model simulation estimated reduction of ET with 0.0851% with an increase of runoff by 0.051%. Among the vegetation parameters, leaf area index (LAI) emerged as the most sensitive one to alter the simulated water balance. LULC alterations via deforestation, urbanization, cropland expansions led to reduced canopy cover for interception and transpiration that in turn contributed to overall decrease in ET and increase in runoff and base flow. This study reiterates changes in the hydrology due to LULCC, thereby providing useful inputs for integrated water resources management in the principle of sustained ecology.  相似文献   

Hazardous area map: an approach of sustainable urban planning and industrial development—a review     

Ganguly  Madhurima  Aynyas  Rahul  Nandan  Abhishek  Mondal  Prasenjit 《Natural Hazards》2018,91(3):1385-1405

Natural Hazards - A hazard map is a map which shows about all the vulnerable regions present in any country or at any specific place or location which is affected or will be affected by natural...  相似文献   

Effects of primordial magnetic field on the formation rate of dark matter halos     

Varalakshmi Cheera  Rahul Nigam 《Astrophysics and Space Science》2018,363(5):93

We construct and demonstrate a method for computing the formation rate of the dark matter halo in the hierarchical model set up. This method uses the Press-Schecter distribution for the halos and hence applies only to the spherical halos. But this can be generalized to ellipsoidal structures also if one uses the Sheth-Torman distribution. After obtaining the formation rate, we study the effect of primordial magnetic field on the dynamics of these halos. We investigate the effect for different field strengths and conclude that a magnetic field stronger than 10 nG would impact the halos larger than \(10^{8}\) solar masses while a weaker field affects the formation rate of smaller halos.  相似文献   

Physical Properties of Umbral Dots Observed in Sunspots: A <Emphasis Type="Italic">Hinode</Emphasis> Observation     

Rahul Yadav  Shibu K. Mathew 《Solar physics》2018,293(4):54

Umbral dots (UDs) are small-scale bright features observed in the umbral part of sunspots and pores. It is well established that they are manifestations of magnetoconvection phenomena inside umbrae. We study the physical properties of UDs in different sunspots and their dependence on decay rate and filling factor. We have selected high-resolution, G-band continuum filtergrams of seven sunspots from Hinode to study their physical properties. We have also used Michelson Doppler Imager (MDI) continuum images to estimate the decay rate of selected sunspots. An identification and tracking algorithm was developed to identify the UDs in time sequences. The statistical analysis of UDs exhibits an averaged maximum intensity and effective diameter of 0.26 \(I_{\mathrm{QS}}\) and 270 km. Furthermore, the lifetime, horizontal speed, trajectory length, and displacement length (birth–death distance) of UDs are 8.19 minutes, 0.5 km?s^?1, 284 km, and 155 km, respectively. We also find a positive correlation between intensity–diameter, intensity–lifetime, and diameter–lifetime of UDs. However, UD properties do not show any significant relation with the decay rate or filling factor.  相似文献   

Thermonuclear X-ray burst of MXB 1658-298 with <Emphasis Type="Italic">NuSTAR</Emphasis>     

Rahul Sharma  Abdul Jaleel  Chetana Jain  Biswajit Paul  Anjan Dutta 《Journal of Astrophysics and Astronomy》2018,39(1):16

MXB 1658-298 is a transient Low-Mass X-ray Binary (LMXB), which shows eclipses, dips and bursts in its light curve. This source has undergone three active periods separated by long quiescent phases. The latest phase of enhanced X-ray emission was observed during 2015–2016. We have analysed broadband data from Swift/XRT and NuSTAR observations carried out in 2015. During NuSTAR observation, one thermonuclear X-ray burst took place. The X-ray emission during the burst was brighter by a factor of \(\sim 200\), compared to the pre-burst emission. This work focuses on the spectral analysis of MXB 1658-298 during the persistent and the burst phases using NuSTAR observation of 2015. We have also determined the temperature and radius evolution during the burst using the time-resolved spectroscopy. The burst phase shows mild Photospheric Radius Expansion (PRE).  相似文献