The Palaeomagnetism of some Scottish Tertiary Dykes and their Baked Contacts     

P. K. S. Raja 《Geophysical Journal International》1964,9(1):15-19

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Ductility of reinforced concrete sections with confined compression zones     

Prakash Desayi  K. T. Raja Sundara Iyengar  K. Nagi Reddy 《地震工程与结构动力学》1975,4(2):111-118

Confinement of concrete in circular spiral steel binders imparts to it considerable ductility and also some increase in strength. This property can be utilized in designing concrete structures to withstand seismic forces where the members are required to possess not only strength but also energy absorbing capacity. Assuming the stress-strain behaviour of confined concrete as elastic-plastic, the ductility factor for strain and the strength factor (denoting increase in strength) have been determined for concrete confined to different degrees. Similarly, assuming the moment-curvature behaviour of reinforced concrete sections with confined compression concrete to be elastic-plastic, the ductility factor for curvature has been determined for such beams. The computed moment-curvature plots have been found to compare satisfactorily with tests on 18 beams. Ductility factors for curvature of singly and doubly reinforced concrete sections with compression concrete confined to different degrees have been determined and presented for certain typical cases. Such plots would be of use in designing reinforced concrete beam sections for required ductility.  相似文献   

A palaeomagnetic study of lower Proterozoic granites from Western Kenya     

J. P. Patel  P. K. S. Raja 《Geophysical Journal International》1979,58(2):279-286

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Linkage between rainfall singularities and geomagnetic activity     

R. S. Reddy  K. S. Raja Rao  Bh. V. Ramana Murty 《Meteorology and Atmospheric Physics》1984,33(2-3):127-142

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Heavy metal concentrations in shallow marine sediments affected by submarine tailings disposal and artisanal gold mining,Buyat-Ratototok district,North Sulawesi,Indonesia     

Evan N. Edinger  P. Raja Siregar  George M. Blackwood 《Environmental Geology》2007,52(4):701-714

Trace element concentrations in shallow marine sediments of the Buyat-Ratototok district of North Sulawesi, Indonesia, are affected by submarine disposal of industrial gold mine tailings and unregulated dumping of tailings and wastewater from small-scale gold mining using mercury amalgamation. Industrial mine tailings contained 590–690 ppm arsenic, 490–580 ppm antimony, and 0.8–5.8 ppm mercury. Tailings-affected sediment As and Sb concentrations were 20–30 times higher than in muddy sediments not contaminated with tailings, and 50–60 times higher than pre-mining average. Highest mercury concentrations were observed in sediments affected by small-scale mining using mercury amalgamation (5–29 ppm). Concentrations of most other trace elements were comparable in sediments affected by both types of mining and were slightly higher than regional averages for sediments collected before the onset of industrial mining. Elevated concentrations of both As and Sb in approximately equal proportions suggest tailings dispersal of at least 3.5 km. Mercury released from artisanal gold mining dispersed up to 4 km from river mouths. Slight increases in concentrations of non-mercury trace elements in areas affected by artisanal mining over pre-industrial mining concentrations were probably caused by increased rates of erosion. Electronic supplementary material Supplementary material is available in the online version of this article at and is accessible for authorized users.  相似文献   

Inter-annual and seasonal variations in hydrological parameters and its implications on chlorophyll a distribution along the southwest coast of Bay of Bengal     

Shanthi R.  Poornima D.  Raja K.  Sarangi R. K.  Saravanakumar A.  Thangaradjou T. 《海洋学报(英文版)》2015,34(6):94-100

Seasonal and inter-annual variability of hydrological parameters and its impact on chlorophyll distribution was studied from January 2009 to December 2011 at four coastal stations along the southwest Bay of Bengal. Statistical analysis(principal component analysis(PCA), two-way analysis of variance(ANOVA) and correlation analysis)showed the significant impact of hydrological parameters on chlorophyll distribution in the study area. The ranges of different parameters recorded were 23.8–33.8°C(SST), 4.00–36.00(salinity), 7.0–9.2(p H), 4.41–8.32 mg/L(dissolved oxygen), 0.04–2.45 μmol/L(nitrite), 0.33–16.10 μmol/L(nitrate), 0.02–2.51 μmol/L(ammonia),0.04–3.32 μmol/L(inorganic phosphate), 10.09–85.28 μmol/L(reactive silicate) and 0.04–13.8 μg/L(chlorophyll).PCA analysis carried out for different seasons found variations in the relationship between physico-chemical parameters and chlorophyll in which nitrate and chlorophyll were positively loaded at PC1(principal component1) during spring inter-monsoon and at PC2(principal component 2) during other seasons. Likewise correlation analysis also showed significant positive relationship between chlorophyll and nutrients especially with nitrate(r=0.734). Distribution of hydrobiological parameters between stations and distances was significantly varying as evidenced from the ANOVA results. The study found that the spatial and temporal distribution of chlorophyll was highly dependent on the availability of nutrients especially, nitrate in the southwest Bay of Bengal coastal waters.  相似文献   

RESOURCESAT-1 LISS-4 MX bands onground co-registration by in-flight calibration and attitude refinement     

S. Manthira Moorthi  Raja Kayal  R. Rama Krishnan  P.K. Srivastava 《International Journal of Applied Earth Observation and Geoinformation》2008,10(2):140-1

RESOURCESAT-1 satellite was launched in October of 2003. Since then it has been consistently providing high quality 5 m monochromatic and multispectral images of same resolution. LISS-4 MX sensor has complex acquisition geometry. It operates in three spectral bands imaged by 3 CCD arrays, which are separated by a finite time in imaging along the satellite track direction. Individual band data is acquired at different times while the satellite is driven by a pre-determined yaw profile. In addition, the odd–even pixels are too shifted by a small fixed delay in time. A unique challenge in LISS-4 MX Level-2 data processing sub-system is to autonomously rectify and additionally co-register the three bands data because of the influence of orbit and attitude in the time gap in the imaging sequence. In this paper, authors bring out details of in-flight calibration arrived for LISS-4 MX sensor. It addresses parameterization of co-registration problem by doing sensitivity analysis of the geometric model parameters to achieve co-registration among all bands. This approach can also be used for other sensor system having similar imaging geometry to achieve improved image co-registration among bands.  相似文献   

Agent-Based Simulation of Urban Residential Dynamics and Land Rent Change in a Gentrifying Area of Boston     

Jeremy Jackson  Benjamin Forest  Raja Sengupta 《Transactions in GIS》2008,12(4):475-491

Certain complex processes are most effectively modeled not on the macro-scale, but from the bottom-up, by simulating the decisions of individual entities, or agents. This study uses an agent-based modeling (ABM) approach to simulate residential dynamics in an area of Boston that has increasingly experienced gentrification in the past decades. The model is instantiated using basic empirical data and uses simple decision-making rules, differentiated into four classes, to simulate the process of residential dynamics. The model employs the consumption explanation of the cause of gentrification, which emphasizes the choices of individuals drawn to urban amenities, while testing the production explanation, which suggests that major investments from the public and private sphere attract and explain gentrification. Verification shows that the processes in the model work according to its construction, simulates complexity and emergent phenomena, and may be a valuable explanatory tool for understanding and learning about some processes underlying gentrification.  相似文献   

Heavy metal contamination from gold mining recorded in Porites lobata skeletons, Buyat-Ratototok district, North Sulawesi, Indonesia     

Edinger EN  Azmy K  Diegor W  Siregar PR 《Marine pollution bulletin》2008,56(9):1553-1569

Shallow marine sediments and fringing coral reefs of the Buyat-Ratototok district of North Sulawesi, Indonesia, are affected by submarine disposal of tailings from industrial gold mining and by small-scale gold mining using mercury amalgamation. Between-site variation in heavy metal concentrations in shallow marine sediments was partially reflected by trace element concentrations in reef coral skeletons from adjacent reefs. Corals skeletons recorded silicon, manganese, iron, copper, chromium, cobalt, antimony, thallium, and lead in different concentrations according to proximity to sources, but arsenic concentrations in corals were not significantly different among sites. Temporal analysis found that peak concentrations of arsenic and chromium generally coincided with peak concentrations of silica and/or copper, suggesting that most trace elements in the coral skeleton were incorporated into detrital siliciclastic sediments, rather than impurities within skeletal aragonite.  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