Tidal disruption of a disk galaxy     

Tapan K. Chatterjee  Farooq Ahmed 《Astrophysics and Space Science》1981,75(2):501-509

The tidal force effects of a spherical galaxy passing head-on through a disk galaxy have been studied for various orientations of the disk galaxy with respect to the direction of relative motion of the two galaxies. The density distribution of the spherical galaxy is taken to be that of a polytrope of indexn=4 and that of the disk galaxy is taken to be, (r)=_ce^–4r/R, where _c is the central density andR the radius of the disk. It is found that the disruptive effects due to the tidal force are minimum when the plane of the disk lies along the direction of relative motion, but are maximum when the plane of the disk is slightly inclined to this direction (about 15°). The tidal force effects at the median radius have also been computed. The tadal force effects are much higher in the interior region of the disk.  相似文献   

A hydro-structural analysis program for TLPS     

P.C. Chatterjee  P.K. Das  D. Faulkner 《Ocean Engineering》1997,24(4):313-334

The TLP configuration in this paper comes from the case study of the ISSC Derived Loads Committee I.2 in 1985. Two models, Model 1 and Model 2, are created aiming at developing a computational tool to handle hydro-dynamic and structural aspects together to help the TLP designer. Another objective is to generate relevant information for a non-linear static local stress analysis of TLP components from a dynamic hydro-structural global analysis. Model 2 is developed for LUSAS, a general purpose, well established, FE software, to validate the in-house program DCATLP. Model 1 and Model 2 are purposely made slightly different in the tether modelling so that the non-linear formulations in DCATLP to treat a TLP as a coupled system with the hull and tethers can be verified with a straightforward linear step-by-step dynamic analysis in LUSAS. The code in DCATLP has advanced features to account for some complex aspects of TLPs, such as compliant characteristics. The results from DCATLP can be directly used in the reliability based structural design of TLP components and subsequent optimisation studies.  相似文献   

Chemical and isotopic composition of the lower crust beneath the Meguma Lithotectonic Zone,Nova Scotia: evidence from granulite facies xenoliths     

G. W. Eberz  D. B. Clarke  A. K. Chatterjee  P. S. Giles 《Contributions to Mineralogy and Petrology》1991,109(1):69-88

Granulite-facies xenoliths from an Upper Devonian lamprophyre dyke near Tangier, Nova Scotia, provide new information about the lower crust in the Meguma Zone. Two mineralogically and chemically distinet groups of xenoliths occur. Both groups contain quartz+feldspar+biotite+Fe–Ti oxides+sulfides. In addition, group A contains garnet+graphite±[aluminosilicates+spinel±sapphirine (hight Al₂O₃ subgroups A1 and A2)] or [clinopyroxene+sphene+apatite (high CaO sub-group A3)]. Group B has highly variable proportions of orthopyroxene (B1), clinopyroxene (B2), and amphibole (B3). Trace-element contents of the highly aluminous xenoliths compare closely with average to upper crustal model compositions and are similar in many aspects to other undepleted granulite-facies rocks. LowP-T sedimentary assemblages of quartz-chlorite-clay minerals-calcite-albite or paragonite can account for the compositions of group A xenoliths. Within group B, a high-MgO (MgO>13 wt%) subgroup with high transition-metal contents, and low-MgO (MgO<9 wt%) sub-groups with higher LIL (large-ion-lithophile) element contents exist. Although the rare-earth and high-field-strength elements indicate a tholeiitic or low-K calc-alkaline chemistry, the LIL elements are as high as those from high-K calc-alkaline volcanic are rocks. Isotopically, group A ranges from Nd_t=-2.56 to-0.80 and⁸⁷Sr/⁸⁶Sr _t =0.7046 to 0.7182 fort=370 Ma. For group B these values are +1.45 to +5.33 and 0.7028 to 0.7048, respectively. Model ages (T_CHUR) are correspondingly low and are tightly constrained (544±52 Ma). These young ages contrast with the middle Proterozoic Nd model ages of the overlying Meguma Zone low-grade flysch. This time-inverted stratigraphy appears to be the product of a tectonic break between a younger autochthonous Tangier lower crust (Avalon), and an older allochthonous Meguma Group upper crust.  相似文献   

Chandra smells a RRAT     

Bryan M. Gaensler  Maura McLaughlin  Stephen Reynolds  Kazik Borkowski  Nanda Rea  Andrea Possenti  Gianluca Israel  Marta Burgay  Fernando Camilo  Shami Chatterjee  Michael Kramer  Andrew Lyne  Ingrid Stairs 《Astrophysics and Space Science》2007,308(1-4):95-99

“Rotating RAdio Transients” (RRATs) are a newly discovered astronomical phenomenon, characterised by occasional brief radio bursts, with average intervals between bursts ranging from minutes to hours. The burst spacings allow identification of periodicities, which fall in the range 0.4 to 7 seconds. The RRATs thus seem to be rotating neutron stars, albeit with properties very different from the rest of the population. We here present the serendipitous detection with the Chandra X-ray Observatory of a bright point-like X-ray source coincident with one of the RRATs. We discuss the temporal and spectral properties of this X-ray emission, consider counterparts in other wavebands, and interpret these results in the context of possible explanations for the RRAT population. B.M.G. acknowledges the support of NASA through LTSA grant NAG5-13023 and of an Alfred P. Sloan Fellowship.  相似文献   

Flood risk modeling for optimal rice planning for delta region of Mahanadi river basin in India     

Dibyendu Samantaray  Chandranath Chatterjee  Rajendra Singh  Praveen Kumar Gupta  Sushma Panigrahy 《Natural Hazards》2015,76(1):347-372

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Evaluation on the change characteristics of ecosystem service in Dhanbad district of Jharkhand,India based on land use change     

Ankur  Pathik  Chatterjee  Soumen  Gupta  Krishnendu 《GeoJournal》2022,87(4):413-437

Ecosystem services (ESs) simply refer to those services conferred by Mother Nature for the survival of her offspring living within. But the provision of ESs is continuously affected by human activity and related changes like transformations in land use and land cover. The present study has been initiated to evaluate the pattern of landscape transformation and its impact on ecosystem service, along with estimating the per capita availability of ESs based on remotely sensed data in the Dhanbad district, Jharkhand, India. The result shows that the total ecosystem service value (ESV) loss of the district was $2251959.76 during 1990–2020. The highest loss of ESV was recorded due to the conservation of agricultural land to built-up area ($15884988.50) and vegetation cover on agricultural land ($14451545.01), while the increased vegetation cover on other types of land helped the district to gain back some balance over the loss. But in a smaller scale study, 5 out of the 8 spatial units are facing negative change in ESV, and unfortunately, they are altogether inhabited by more than 85% of the district's total population. That means the loss of ESV is greater where it needs to be more as per population. Moreover, the per capita ESs in the district decreased by 68.48%, while among the spatial units in Dhanbad it decreased the most (89.60%), which is a serious cause for worry in the future. Therefore, this study can contribute to the process of decision-making, proposing ecological conservation and sustainable development plans for the region.

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Analysis of eve-teasing potential zones using geospatial technologies and AHP: a study in Midnapore town,West Bengal,India     

Biswas  Priyanka  Das  Kousik  Das Chatterjee  Nilanjana 《GeoJournal》2021,86(3):1043-1072

GeoJournal - Application of geospatial technologies in criminological study is most relevant in present day context. Crime mapping with the help of Geographical Information System is being a very...  相似文献   

Concentration of polybrominated diphenyl ethers (PBDEs) in sediment cores of Sundarban mangrove wetland, northeastern part of Bay of Bengal (India)   总被引：4，自引：0，他引：4  

Binelli A  Sarkar SK  Chatterjee M  Riva C  Parolini M  Bhattacharya BD  Bhattacharya AK  Satpathy KK 《Marine pollution bulletin》2007,54(8):1220-1229

The paper presents the first comprehensive survey of congener profiles (12 congeners) of polybrominated diphenyl ethers (PBDEs) in core sediment samples (<63 microm) covering seven sites in Sundarban mangrove wetland (India). Gas-chromatographic analyses were carried out in GC-Ms/Ms for tri- to hepta- brominated congeners. Results pointed out a non-homogenous contamination of the wetland with summation operator(12) PBDE values ranging from 0.08 to 29.03 ngg(-1), reflecting moderate to low contamination closely in conformity to other Asian aquatic environments. The general order of decreasing congener contribution to the total load was: BDE 47>99>100>154, similar to the distribution pattern worldwide. Although tetrabromodiphenyl ether BDE 47 was found in all samples followed by hexabromodiphenyl ether BDE-154, they were not necessarily the dominant congeners. No uniform temporal trend on PBDE levels was recorded probably due to particular hydrological characteristics of the wetland and/on non-homologous inputs from point sources (untreated municipal wastewater and local industries, electronic wastes from the dump sites, etc.) of these compounds. Because of the propensity of PBDEs to accumulate in various compartments of wildlife and human food webs, evaluation of biological tissues should be undertaken as a high priority.  相似文献   

Electrical resistivity investigation of the arsenic affected alluvial aquifers in West Bengal,India: usefulness in identifying the areas of low and high groundwater arsenic   总被引：1，自引：1，他引：0  

Bibhash Nath  Sukumar Basu Mallik  Doris Stüben  Debashis Chatterjee  Laurent Charlet 《Environmental Earth Sciences》2010,60(4):873-884

This study aims at finding out possible relation between lithology and spatial pattern of dissolved arsenic (As) in groundwater around Chakdaha municipality, West Bengal, India. Satellite image, coupled with electrical resistivity survey and borehole drilling helps to delineate surface and sub-surface lithological framework of the As affected alluvial aquifers. The satellite imagery demonstrate that the high As area are presumably under active flood plain environment (low-lying areas), that constantly receive organics due to periodic flooding. Thick low resistive (fine-grained) layer was observed at the top around the high As areas, which, however, not found in low As areas. The result suggests that hydraulic properties of the surface/sub-surface soil/sediment have an important control on the fate and transport of As in the aquifer. This study demonstrates that electrical resistivity tools can be effectively used for the reconnaissance survey in characterizing the plausible lithological framework of an alluvial aquifer containing As.  相似文献   

On the aftershock sequence of a 4.6 mb earthquake of the Garhwal Himalaya     

Irene Sarkar  Ramesh Chander  Dalia Chatterjee 《Journal of Earth System Science》1995,104(4):683-691

Locally recorded data for eighteen aftershocks of a magnitude(m_b) 4.6 earthquake occurring near Ukhimath in the Garhwal Himalaya were analysed. A master event technique was adopted to locate seventeen individual aftershock hypocentres relative to the hypocentre of the eighteenth aftershock chosen as the master event. The aftershock epicentres define an approximately 30 km² rupture zone commensurate with the magnitude of the earthquake. The distribution of epicentres within this zone and the limited amount of first motion data support the view that a group of parallel, sub-vertical, sinistral strike-slip faults oriented N46°, transverse to the regional NW-SE trend of the Garhwal Himalaya, was involved in this seismic episode. Since the estimated focal depth range for aftershocks of this sequence is 3–14 km, we infer that this transverse fault zone extends through the upper crustal layer to a depth of 14 km at least.  相似文献