Deciphering the desiccation trend of the South Asian monsoon hydroclimate in a warming world     

R. Krishnan  T. P. Sabin  R. Vellore  M. Mujumdar  J. Sanjay  B. N. Goswami  F. Hourdin  J.-L. Dufresne  P. Terray 《Climate Dynamics》2016,47(3-4):1007-1027

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Monsoon-extratropical circulation interactions in Himalayan extreme rainfall     

Ramesh K. Vellore  Michael L. Kaplan  R. Krishnan  John M. Lewis  Sudhir Sabade  Nayana Deshpande  Bhupendra B. Singh  R. K. Madhura  M. V. S. Rama Rao 《Climate Dynamics》2016,46(11-12):3517-3546

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Study of average heat fluxes in various layers of the soil and their seasonal variation in Jodhpur     

A. Krishnan  Prof. R. S. Kushwaha 《Theoretical and Applied Climatology》1974,22(3):247-256

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Case studies of damage to 19‐storey irregular steel moment‐frame buildings under near‐source ground motion     

Swaminathan Krishnan 《地震工程与结构动力学》2007,36(7):861-885

This paper describes the three‐dimensional nonlinear analysis of six 19‐storey steel moment‐frame buildings, designed per the 1997 Uniform Building Code, under strong ground motion records from near‐source earthquakes with magnitudes in the range of 6.7–7.3. Three of these buildings possess a reentrant corner irregularity, while the remaining three possess a torsional plan irregularity. The records create drift demands of the order of 0.05 and plastic rotation demands of the order of 4–5% of a radian in the buildings with reentrant corners. These values point to performance at or near ‘Collapse Prevention’. Twisting in the torsionally sensitive buildings causes the plastic rotations on the moment frame on one face of the building (4–5% of a radian) to be as high as twice of that on the opposite face (2–3% of a radian). The asymmetric yield pattern implies a lower redundancy in the lateral force‐resisting system as the failure of the heavily loaded frame could result in a total loss of resistance to torsion. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   

Observations of the atmospheric surface layer parameters over a semi arid region during the solar eclipse of August 11th, 1999     

Praveena Krishnan  P. K. Kunhikrishnan  S. Muraleedharan Nair  Sudha Ravindran  Radhika Ramachandran  D. B. Subrahamanyam  M. Venkata Ramana 《Journal of Earth System Science》2004,113(3):353-363

This paper discusses the observations of the Atmospheric Surface Layer (ASL) parameters during the solar eclipse of August 11th, 1999. Intensive surface layer experiments were conducted at Ahmedabad (23‡21′N, 72‡36′E), the western part of India, which was close to the totality path. This rare event provided by nature is utilised to document the surface layer effects during the eclipse period using measurements of high frequency fluctuations of temperature, tri-axial wind components as well as mean parameters such as temperature, humidity, wind speed and subsoil temperature. Analysis showed that during the eclipse period, the turbulence parameters were affected leading to the suppression of the turbulence process, the main dynamic process in the atmospheric boundary layer, while the mean parameters showed variations within the natural variability of the observational period. The spectra of the wind components and temperature indicated decrease in spectral power by one order in magnitude during the eclipse period. The rate of dissipation of turbulent kinetic energy is found to decrease by more than one order during the eclipse period. The stability parameter showed a change from unstable to stable condition during the period of eclipse and back to unstable condition by the end of eclipse  相似文献   

A critical study of evaporation by Penman's method during the growing season of vegetation in the arid Zone of India     

Dr. A. Krishnan  Prof. R. S. Kushwaha 《Theoretical and Applied Climatology》1971,19(3):267-276

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Choice of a teleseismicP-wave travel-time model and the associated source corrections     

S. K. Arora  C. A. Krishnan 《Pure and Applied Geophysics》1972,101(1):74-89

Summary Among various trial models ofP-wave travel times, there exists at least one model which best predicts the times of first arrivals from a certain region at a set of recording stations even if no attempt is made to correct the travel-time standards against known station errors and source bias. In teleseismic distance range (25°100°) and surface-focus case, the possibility of statistically establishing which of the twoP models, viz. Jeffreys-Bullen and Herrin, is more appropriate for each of the four source regions, viz. Southern Nevada, Aleutian Islands, Eastern Kazakh and Novaya Zemlya, is discussed in this paper. Data corresponding to a set of underground explosions from these regions form the basis of such an analysis. The Herrin model is found to be better applied to Aleutian Islands region while the Jeffreys-Bullen model seems more appropriate for each of the remaining three regions.As a result of the study of the travel-time models, numerical estimates of space and time corrections pertaining to the above mentioned regions, based on the most appropriate model and directly applicable to the computed source parameters, are obtained. On applying these corrections, the size of source location error ellipse and the source-time error reduce to very small representative values, viz. 4 km×6 km (area 75 km²) and ±0.2 sec respectively.  相似文献   

Antibiotic resistant pathogens versus human impacts: a study from three eco-regions of the Chennai coast, southern India   总被引：1，自引：0，他引：1  

Vignesh S  Muthukumar K  James RA 《Marine pollution bulletin》2012,64(4):790-800

We assessed the occurrence of pollution indicators and antibiotic resistant bacterial isolates from water and sediment samples of three different eco-regions of the Chennai coast between March - May of 2010. Total of 960 bacterial strains belonging to four genera were isolated which show the highest frequencies of resistance to vancomycin (53.6%) and penicillin (52.6%) (except Enterococcus sp., which is highly resistant to erythromycin) and lowest frequencies of resistance to chloramphenicol (3.43%), ciprofloxacin (3.95%), gentamicin (4.68%), and tetracycline (6.97%). The E. coli, Vibrio sp., Salmonella sp. and Enterococcus sp. show high frequency of resistance to 2-5 antibacterials of 60.4%, 45.83%, 69.16% and 46.6%, respectively. High pollution indices (PI - 6.66-14.06) and antibiotic resistance indices (ARI - 0.29-0.343) indicate that the coastal environment is highly exposed to antibiotic sources that suggesting to avoid direct contact.  相似文献   

Establishment of Baseline Reference Geochemical Values in Tropical Soils of Western Ghats: Assessment of Periyar Basin with Special Reference to Contaminant Geochemistry     

Appukuttanpillai Krishnakumar  Sanal Kumar Aditya  Krishnan Anoop Krishnan  Nandakumar Vivekanandan  Seenipandi Kaliraj  Jeenu Jose 《洁净——土壤、空气、水》2023,51(2):2200382

Based on the detailed geochemical studies of 184 soil samples from Periyar River Basin (PRB), a tropical monsoon dominated river basin (5398 km²) in the southern western Ghats (WGs) of India, a baseline reference data is established. The soils are mildly acidic with sandy loam and silt loam facies in non-monsoon to sandy loam and sandy clay loam in monsoon. The mean metal concentrations follow the upper continental crust and world shale values. The Geoaccumulation index (Igeo) shows unpolluted to moderately polluted category, except for Cu, Zn, and Ba, while Enrichment Factor (EF) indicates no to minor enrichment for all elements. Contamination factor (Cf) indicates low to considerable contamination for V, Rb, Sr, Ni, and low to very high contamination for Cu, Zn, and Ba. Three significant components are extracted by Principal Component Analysis (PCA), explaining 78.09% and 74.10% of the total variance for monsoon and non-monsoon seasons. Ti, Al, Fe, Ca, Na, K, V, Cr, Ni, Sr, and Ba exhibited common source of origin while anthropogenic origin is identified for Zn and Cu. The study will provide valuable information into the pedological characteristics of WGs river basins.  相似文献   

Stomach contents of cetaceans incidentally caught along Mangalore and Chennai coasts of India     

Anoop A. Krishnan  K.S. Yousuf  P.L. Kumaran  N. Harish  B. Anoop  V.V. Afsal  M. Rajagopalan  E. Vivekanandan  P.K. Krishnakumar  P. Jayasankar 《Estuarine, Coastal and Shelf Science》2008,76(4):909-913

The stomachs of 32 individuals of seven cetacean species incidentally caught in gill net and purseseine fisheries along Mangalore and Chennai coasts (India) between 2004 and 2006 were examined. The whole stomach (fore-gut, mid-gut and hind-gut) was examined in all cases. Prey remains (666 prey items comprising six species of teleosts, one crustacean and one squid species) were found in the stomachs of eight individuals (the remaining 24 stomachs were found to be empty). All cetaceans were found to feed mostly on teleosts with wide range of trophic levels. Based on an index that included frequency of occurrence, percentage by number and by weight, the oil sardine Sardinella longiceps was the main prey in the sample. Cetaceans appear to favour both pelagic as well as demersal prey, possibly indicating surface and benthic feeding habits.  相似文献