Auxiliary functions of the Hilbert transform in the study of gravity anomalies     

G. Ramadass  I. Arunkumar  S. M. Varaprasada Rao  N. L. Mohan  N. Sundararajan 《Journal of Earth System Science》1987,96(3):211-219

The auxiliary functions, namely amplitude, phase, envelope and instantaneous frequency of Hilbert transform over gravity anomalies of 2-D sphere, vertical fault block and horizontal circular cylinder are studied. The characteristics of these functions are established in locating and identifying the sources. The method is illustrated with a theoretical example in each case and supported by field data of gravity anomaly over Humble dome and spherical model of the Satak-Mansar area, Nagpur District, India.  相似文献   

Analysis of gravity gradients over a thin infinite sheet     

N. Sundararajan  I. Arun Kumar  N. L. Mohan 《Journal of Earth System Science》1987,96(1):11-14

A simple method to interpret gravity gradients over a thin infinite dipping sheet is discussed. The Hilbert transform is used to compute the vertical gradient from the horizontal gradient of the gravity field. The method is illustrated with a theoretical example.  相似文献   

Assessment of groundwater quality in and around Vedaraniyam,South India   总被引：1，自引：1，他引：0  

P. Krishnakumar  C. Lakshumanan  V. Pradeep Kishore  M. Sundararajan  G. Santhiya  S. Chidambaram 《Environmental Earth Sciences》2014,71(5):2211-2225

Groundwater from 47 wells were analyzed on the basis of hydrochemical parameters like pH, electric conductivity, total dissolved solids, Ca²⁺, Mg²⁺, Na⁺, K⁺, Cl^?, CO₃ ^2?, HCO₃ ^?, NO₃ ^?, PO₄ ^3? and F^? in the Cauvery delta of Vedaraniyam coast. Further, water quality index (WQI), sodium percentage (Na %), sodium absorption ratio, residual sodium carbonate, permeability index and Kelley’s ratio were evaluated to understand the suitability of water for drinking and irrigation purposes. The result shows significant difference in the quality of water along the coastal stretch. The order of dominance of major ions is as follows: Na⁺ ≥ Mg²⁺ ≥ Ca²⁺ ≥ K⁺ and Cl^? ≥ HCO₃ ^? ≥ CO₃ ^2? ≥ PO₄ ^3? ≥ F^?. Na/Cl, Cl/HCO₃ ratio and Revelle index confirmed that 60–70 % of the samples were affected by saline water intrusion. WQI showed that 36 % of the samples were good for drinking and the remaining were poor and unsuitable for drinking purpose. The degradation of groundwater quality was found to be mainly due to over-exploitation, brackish aquaculture practice, fertilizer input from agriculture and also due to domestic sewage.  相似文献