Dynamics of the stationary eddies in the lower stratospheric circulation in the wavenumber domain and monsoon activity     

K S Raja Rao  S T Awade  M V Harindranathan Nair 《Journal of Earth System Science》1984,93(1):1-16

Meridional transports of momentum and sensible heat have been computed using the Fourier coefficients of the geopotential heights at 50 mb and 30 mb levels for each month during the years 1972 to 1979. Seasonal variations in these transports and in the energy conversionsC (K _E ,K _Z ) andC (A _z ,A _E ) in the contrasting years of monsoon activity have been discussed. The transport and the conversion terms undergo annual variations only with winter maxima and summer minima. Large northward transport of momentum and of sensible heat in the low latitude summer and in the high latitude preceeding winter suggests a linkage between monsoon activity and high latitude stratosphere. Seasonal variations in the energy conversion termsC (K _E ,K _Z ) andC (A _Z ,A _E ) conform with the changes in the system in the years of widely differing monsoon activity both in low and high latitudes. Large conversion of energy fromA _Z toA _E in low latitude summer indicates weakening of the existing meridional temperature gradient, in bad monsoon years.  相似文献   

Palaeomagnetism of the tororo ring complex,S.E. Uganda     

P.K.S. Raja  J.B. Vise 《Earth and Planetary Science Letters》1973,19(4):438-442

Palaeomagnetic measurements on the pre-Miocene carbonatite volcanics of Tororo, S.E. Uganda, have yielded a pole at 75.8°N, 195.5°E with A₉₅ = 9.4°. Along with the Tertiary poles from East African rift systems, the Eocene-Oligocene pole from Ethiopia and the mean Mesozoic pole from the rest of Africa, a polar wander path for Africa fromMesozoic to present is suggested.  相似文献   

Malaysian fisheries policy : Search for new grounds     

Ishak Hj Omar  Kusairi Mohd Noh  Nik Mustapha Raja Abdullah  K. Kuperan 《Marine Policy》1992,16(6)

Past fisheries development policies in Malaysia are assessed and new grounds for managing the Malaysian fisheries are explored. Some incompatibility in the goals for fishery development are discerned, especially those of increasing domestic landings through mechanization and resource conservation. Future management efforts should be based on a fuller understanding of the fishery stock and regional management of fish stocks. Aquaculture is often seen as a plausible alternative in order to augment supplies from the capture fisheries. A comprehensive multidisciplinary approach is needed to transform and commercialize traditional, experience-dependent culture systems into technology-packaged systems based on scientific methods. There is also substantial potential for the development of recreational fisheries.  相似文献   

The peculiar cluster MACS J0417.5-1154 in the C and X-bands     

Pritpal Sandhu  Siddharth Malu  Ramij Raja  Abhirup Datta 《Astrophysics and Space Science》2018,363(6):133

We present 5.5 and 9.0 GHz Australia Telescope Compact Array (ATCA) observations of the cluster MACSJ0417.5-1154, one of the most massive galaxy clusters and one of the brightest in X-ray in the Massive Cluster Survey (MACS). We estimate diffuse emission at 5.5 and 9.0 GHz from our ATCA observations, and compare the results with the 235 MHz and 610 MHz GMRT observations and 1575 MHz VLA observations. We also estimate the diffuse emission at low frequencies from existing GLEAM survey data (using the MWA telescope (http://www.mwatelescope.org)), and find that the steepening reported in earlier studies may have been an artefact of underestimates of diffuse emission at low frequencies. High-frequency radio observations of galaxy cluster mergers therefore provide an important complement to low-frequency observations, not only for a probing the ‘on’ and ‘off’ state of radio halos in these mergers, but also to constrain energetics of cluster mergers. We comment on the future directions that further studies of this cluster can take.  相似文献   

Wavelet frame-based feature extraction technique for improving classification accuracy     

R. A. Alagu Raja  V. Anand  S. Maithani  A. Senthil Kumar  V. Abhai Kumar 《Journal of the Indian Society of Remote Sensing》2009,37(3):423-431

Classification of textures in remotely-sensed data has received considerable attention during the past decades. One difficulty of texture analysis in the past was lack of adequate tools to characterize different scales of textures effectively. Recent space-frequency analytical tools like the wavelet transform can effectively characterize the coupling of different scales in texture and helps to overcome the difficulty. This paper presents a wavelet-based texture classification technique that was applied to a Multi-Spectral Scanner (MSS) image of Madurai City, Tamil Nadu, India The feature extraction stage of the technique uses Lemarie-Battle orthogonal wavelets to derive a texture feature vector and this vector is input to a fuzzy-c means classifier, an unsupervised classification procedure. Four indices (user’s accuracy, producer’s accuracy, overall accuracy and Kappa co-efficient) are used to assess the accuracy of the classified data. The experiment results show that the performance of the presented technique is superior to the classical techniques.  相似文献   

Correction to: Landslide susceptibility mapping of the Sera River Basin using logistic regression model     

Raja  Nussaïbah B.  Çiçek  Ihsan  Türkoğlu  Necla  Aydin  Olgu  Kawasaki  Akiyuki 《Natural Hazards》2018,91(3):1423-1423

Natural Hazards - The article “Landslide susceptibility mapping of the Sera River Basin using logistic regression model,” written by Nussaïbah B. Raja, Ihsan Çiçek, Necla...  相似文献   

Heavy Metal Distribution in Sediments of Muthupettai Mangroves,South East Coast of India     

B.Thilagavathi  K.Raja  Bandana Das  A.Saravanakumar  S.Vijayalakshmi  T.Balasubramanian 《青岛海洋大学学报(英文版)》2011,(4):385-390

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Benthic meiofaunal composition and community structure in the Sethukuda mangrove area and adjacent open sea,East coast of India     

Balasubramanaian Thilagavathi  Bandana Das  Ayyappan Saravanakumar  Kuzhanthaivel Raja 《Ocean Science Journal》2011,46(2):63-72

The ecological aspects of meiofaunal communities in the Muthupettai mangrove forest, East coast of India, has not been investigated in the last two decades. Surface water temperature ranged from 23.5 °C to 31.8 °C. Salinity varied from 24 to 34 ppt, while water pH fluctuated from 7.4 to 8.3. Dissolved oxygen concentration ranged from 3.86 to 5.33 mg/l. Meiofauna analysis in this study identified a total of 106 species from the mangrove and adjacent open sea area of Sethukuda. Among these, 56 species of foraminiferans, 20 species of nematodes, 7 species of harpacticoid copepods, 4 species of ostrocodes, and 2 species of rotifers were identified. Furthermore, a single species was identified from the following groups: ciliophora, cnidaria, gnathostomulida, insecta, propulida, bryozoa and polychaete larvae. Meiofaunal density varied between 12029 to 23493 individuals 10 cm/m². The diversity index ranged from 3.515 to 3.680, species richness index varied from 6.384 to 8.497, and evenness index varied from 0.839 to 0876 in the mangrove area and adjacent open sea.  相似文献   

Assessment of heavy metal pollution from the sediment of Tupilipalem Coast,southeast coast of India     

Sreenivasulu Ganugapenta  Jayaraju Nadimikeri  Sundara Raja Reddy Balam Chinnapolla  Lakshmanna Ballari  Rajasekhar Madiga  Nirmala K  Lakshmi Prasad Tella 《国际泥沙研究》2018,33(3):294-302

Sediment from twelve stations was sampled from the Tupilipalem Coast, southeast coast of India, and the presence of a set of heavy metals was established including iron (Fe), manganese (Mn), chromium (Cr), copper (Cu), nickel (Ni), lead (Pb), zinc (Zn) and cadmium (Cd). The heavy metals were assessed by factor analysis, the results of which showed positive and/or negative correlations among Fe, Mn, Cr, Cu, Ni, Pb, Zn, and Cd. Factor analysis also indicated that heavy metals in the sediments of the study area have different natural and anthropogenic sources. Similarly, a sediment pollution assessment was done using the Geoaccumulation Index (Igeo), Enrichment Factor (EF), and Pollution Load Index (PLI). The Geoaccumulation Index indicated that the surface sediment of the Tupilipalem Coast was extremely contaminated with Fe, Mn, Cr, Cu, Ni, Pb, and Zn. The calculation of enrichment factors showed a significant enrichment with respect to Pb, Zn, and Cd and a moderate enrichment with Cr, Cu, and Ni. The falling trend of average contents’ enrichment factors is Cd> Pb> Zn> Cu> Cr> Ni> Mn> Fe. The PLI values of the Cd show higher (>1) values due to the influence of distinct external sources like agricultural runoff, industrial activities, and other anthropogenic inputs. Ninety two percent of heavy metals under study showed the highest concentrations at station TP-5 where the Buckingham Canal and other agricultural and aquacultural effluents connect with the Bay of Bengal. This location is the second inlet which is periodically closed and it seemed that these parts of the study area are heavily affected by anthropogenic pollution.  相似文献   

Automated Detection of Solar Radio Bursts Using a Statistical Method     

Singh  Dayal  Sasikumar Raja  K.  Subramanian  Prasad  Ramesh  R.  Monstein  Christian 《Solar physics》2019,294(8):1-19

Solar Physics - In early September 2017, a series of solar flares and coronal mass ejections (CMEs) erupted from the Sun. The Cor2a coronagraph, a unit of the Sun Earth Connection Coronal and...  相似文献