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Lesser Himalayan sequences in Eastern Himalaya and their deformation:Implications for Paleoproterozoic tectonic activity along the northern margin of India

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Geoscience Frontiers 2013年第3期4卷 289-304页

作者： dilip Saha Geological Studies Unit Indian Statistical Institute203 B.T.RoadKolkata 700108India

Substantial part of the northern margin of Indian plate is subducted beneath the Eurasian plate during the Caenozoic Himalayan orogeny, obscuring older tectonic events in the Lesser Himalaya known to host Proterozoic sedimentary successions and granitic bodies. Tectonostratigraphic units of the Proterozoic Lesser Himalayan sequence （LHS） of Eastern Himalaya, namely the Daling Group in Sikkim and the Bomdila Group in Arunachal Pradesh, provide clues to the nature and extent of Proterozoic passive margin sedimentation, their involvement in pre-Himalayan orogeny and implications for supercontinent reconstruction. The Daling Group, consisting of flaggy quartzite, meta-greywacke and metapelite with minor mafic dyke and sill, and the overlying Buxa Formation with stromatolitic carbonate-quartzite- slate, represent shallow marine, passive margin platformal association. Similar lithostratigraphy and broad depositional framework, and available geochronological data from intrusive granites in Eastern Himalaya indicate strikewise continuity of a shallow marine Paleoproterozoic platformal sequence up to Arunachal Pradesh through Bhutan. Multiple fold sets and tectonic foliations in LHS formed during partial or complete closure of the sea/ocean along the northern margin of Paleoproterozoic India. Such deformation fabrics are absent in the upper Palaeozoic-Mesozoic Gondwana formations in the Lesser Himalaya of Darjeeling-Sikkim indicating influence of older orogeny. Kinematic analysis based on microstructure, and garnet composition suggest Paleoproterozoic deformation and metamorphism of LHS to be distinct from those associated with the foreland propagating thrust systems of the Caenozoic Himalayan collisional belt. Two possibilities are argued here：（1） the low greenschist facies domain in the LHS enveloped the amphibolite to granulite facies domains, which were later tectonically severed; （2） the older deformation and metamorphism relate to a Pacific type accretionary orogen wh

关键词： Garnet composition Kinematics Lesser Himalayan sequence Microstructure Paleoproterozoic Supercontinent

Wave scattering by a horizontal circular cylinder in a three-layer fluid

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Journal of Ocean Engineering and Science 2016年第2期1卷 135-148页

作者： dilip Das Department of Mathematics Shibpur Dinobundhoo Institution(College)Calcutta UniversityHowrahWest BengalIndia

Using linear water-wave theory,wave scattering by a horizontal circular cylinder submerged in a three-layer ocean consisting of a layer of finite depth bounded above by finite depth water with free surface and below by an infinite layer of fluid of greater density is *** cylinder is submerged in either of the three *** such a situation time-harmonic waves with given frequency can propagate with three different wave *** the method of multipoles the problem is reduced to an infinite system of linear equations which are solved numerically by standard technique after *** transmission and reflection coefficients are obtained and depicted graphically against the wave number for all *** a two-layer fluid there are energy identities that exist connecting the transmission and reflection coefficients that *** energy identities are systematically extended to the three-fluid cases which are obtained.

关键词： Three-layer fluid Wave scattering Circular cylinder Reflection and transmission coefficients Energy identities

Reliability assessment of three-dimensional bearing capacity of shallow foundation using fuzzy set theory

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Frontiers of Structural and Civil Engineering 2021年第2期15卷 478-489页

作者： Rajarshi PRAMANIK dilip Kumar BAIDYA Nirjhar DHANG Department of Civil Engineering Indian Institute of Technology KharagpurKharagpur 721302India

The aim of this study is to investigate the applicability of reliability theory on surface square/rectangular footing against bearing capacity failure using fuzzy set theory in conjunction with the finite element *** is modeled as a three-dimensional spatially varying medium,where its parameters(cohesion,friction angle,unit weight,etc.)are considered as fuzzy variables that maintain some membership *** is idealized as an elastic-perfectly plastic material obeying the Mohr-Coulomb failure criterion,where both associated and non-associated flow rules are considered in estimating the ultimate bearing capacity of the *** spatial variability of the soil is incorporated for both isotropic and anisotropic fields,which are determined by the values of scales of fluctuation in both the horizontal and vertical directions.A new parameter namely,limiting applied pressure at zero failure probability is proposed,and it indirectly predicts the failure probability of the *** effect of the coefficient of variation of the friction angle of the soil on the probability of failure is analyzed,and it is observed that the effect is ***,the effect of the scale of fluctuation on the probability of failure is investigated,and the necessity for considering spatial variability in the reliability analysis is well proven.

关键词： finite element method square footing reliability analysis fuzzy set theory coefficient of variation spatial variability

Remote sensing and GIS for land use/cover mapping and integrated land management： case from the middle Ganga plain

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Frontiers of Earth Science 2012年第2期6卷 167-176页

作者： R B SINGH dilip KUMAR Department of Geography Delhi School of EconomicsUniversity of DelhiDelhi 110007India

In India, land resources have reached a critical stage due to the rapidly growing population. This challenge requires an integrated approach toward harnes- sing land resources, while taking into account the vulnerable environmental conditions. Remote sensing and Geographical Information System （GIS） based technologies may be applied to an area in order to generate a sustainable development plan that is optimally suited to the terrain and to the productive potential of the local resources. The present study area is a part of the middle Ganga plain, known as Son-Karamnasa interfluve, in India. Alternative land use systems and the integration of livestock enterprises with the agricultural system have been suggested for land resources management. The objective of this paper is to prepare a land resource development plan in order to increase the productivity of land for sustainable development. The present study will contribute necessary input for policy makers to improve the socio-eeonomic and environmental conditions of the region.

关键词： land use/cover remote sensing GIS middleGanga plain integrated land management

Tuff beds in Kurnool subbasin,southern India and implications for felsic volcanism in Proterozoic intracratonic basins

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Geoscience Frontiers 2012年第4期3卷 429-444页

作者： dilip Saha Vikash Tripathy Geological Studies Unit lndian Statistical InstituteKolkata 700108India A-1/79 Sector-18RohiniNew Delhi 110089India

A first report on tuff beds from the Owk Shale in the Proterozoic Kurnool sub-basin in southern India is presented. The rhyolitic to rhodacitic tufts, overlying shelfal limestones formed at depths below storm wave base, have rheomorphie features indicative of viscoplastic flow, and geochem- ical signatures of rhyolitic to rhyodacitic unwelded to welded tufts, similar to those described from other Proterozoic intracratonic basins like Vindhyan and Chhattisgarh basins in India. Fragmentary nature of altered glass with perlitic cracks and local admixture with intrabasinal sediments suggest phreatomag- matic reactions. The widespread and repeated occurrences of felsic tufts in these basins, possibly derived from low degree melting of continental crust, suggest intermittent tectonothermal instability which likely influenced basinal topography and cyclic development of the carbonate platforms.

关键词： Felsic tuff Intracratonic basin Kumool subbasin Owk Shale Proterozoic

Oilfield geothermal resources of the Upper Assam Petroliferous Basin,NE India

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Energy Geoscience 2021年第4期2卷 246-253页

作者： dilip Majumdar Abhilekha Devi Department of Applied Geology Dibrugarh UniversityAssam786004India

Extracting geothermal energy from the oil-producing fields is an experimental venture *** exploitation and utilization of geothermal energy can partly reduce the larger dependence on conventional non-renewable energy sources like oil,gas,coal,and other fossil fuels,and has a bright *** Upper Assam Basin is a mature petroliferous basin of NE India,where there are several hundred low production,high water cut,or abandoned oil and gas wells that can be retrofitted as geothermal wells instead of drilling new *** will help bridge the gap of growing energy demand and limited supply in energy-deficient state like *** away from the active plate boundaries and in lack of active volcanism,the Upper Assam Basin remains a low-to-medium enthalpy geothermal fluid *** deeper reservoir in this regard can,therefore,be the best candidate for the introspection of the potential geothermal energy reservoir *** selection of a deeper horizon considered in the present case has been the stratified reservoirs of the Lakadong-Therria(Lk-Th)Formation,Sylhet Group of the Lower Eocene age occurring at a variable depth of 3400 me 4600 *** Lk-Th Formation possesses a fair-quality reservoir with lateral continuity and favourable petrophysical *** this study,representative gamma-ray(GR)and resistivity(R)logs were examined to work out lithology,and bed boundary demarcation,*** total Formation thickness varies from 97 to 157 m;the individual sand body thickness is up to 6 *** reservoir parameters,e.g.,porosity(φ=8-33%),water saturation(S_(w)=4.57-95.15%),geothermal gradient(2.71℃/100m to 3.92 C/100 m at 4300 m and 3608 m)respectively,and theoretical estimate of high heat flux in the range 70e100 mW/m^(2)/s,are the necessary yard-stick to measure the subsurface geothermal *** energy extraction will have the potential in facilitating energy utilization for industrial purposes,especially in tea processing units pr

关键词： Upper Assam Petroliferous Basin Geothermal energy Water cut Abandoned oil/gas well Geothermal gradient

Wave radiation by a horizontal circular cylinder submerged in deep water with ice-cover

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Journal of Ocean Engineering and Science 2019年第1期4卷 49-54页

作者： dilip Das Manomita Sahu Department of Mathematics Diamond Harbour Women’s UniversityDiamond Harbour RoadSarisha 743368India

Using the multipoles method,we formulate the problems of water wave radiation(both heave and surge)by a submerged circular cylinder in water with an ice-cover,the ice-cover being modelled as an elastic plate of very small *** leads to an infinite system of linear equations which are solved numerically by standard *** added-mass and damping coefficients for a heaving and surge problems are obtained and depicted graphically against the wave number for various values of flexural rigidity of the ice-cover to show the effect of the presence of ice-cover on these *** the flexural rigidity and surface density of ice-cover are taken to be zero,the ice-cover tends to free-surface then the curves for added-mass and damping coefficients exactly coincide with the curves for the case of water with free *** it is observed that the added-mass and damping coefficients for the two modes of motion are here also the same.

关键词： Water wave radiation Submerged circular cylinder Ice-cover Added mass and damping coefficient.

Liquid vaporization under thermodynamic phase non-equilibrium condition at the gas-liquid interface

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Science China(Technological Sciences) 2020年第12期63卷 2649-2656页

作者： WANG XingJian LAFON Patrick SUNDARAM dilip YANG Vigor Department of Mechanical and Civil Engineering Florida Institute of TechnologyMelbourneFlorida 32901USA Department of Mechanical and Nuclear Engineering The Pennsylvania State UniversityUniversity ParkPA 16802USA School of Aerospace Engineering Georgia Institute of TechnologyAtlantaGA 30332USA

Liquid vaporization under thermodynamic phase non-equilibrium condition at the gas-liquid interface is investigated over a wide range of fluid state typical of many liquid-fueled energy conversion systems. The validity of the phase-equilibrium assumption commonly used in the existing study of liquid vaporization is examined using molecular dynamics theories. The interfacial mass flow rates on both sides of the liquid surface are compared to the net vaporization rate through an order-of-magnitude *** indicated that the phase-equilibrium assumption holds valid at relatively high pressures and low temperatures,and for droplets with relatively large initial diameters(for example,larger than 10 μm for vaporizing oxygen droplets in gaseous hydrogen in the pressure range from 10 atm to the oxygen critical state). Droplet vaporization under superheated conditions is also explored using classical binary homogeneous nucleation theory,in conjunction with a real-fluid equation of state. It is found that the bubble nucleation rate is very sensitive to changes in saturation ratio and pressure;it increases by several orders of magnitude when either the saturation ratio or the pressure is slightly increased. The kinetic limit of saturation ratio decreases with increasing pressure,leading to reduced difference between saturation and superheat conditions. As a result,the influence of nonequilibrium conditions on droplet vaporization is lower at a higher pressure.

关键词： liquid vaporization droplet vaporization superheated vaporization thermodynamic phase equilibrium thermodynamic phase non-equilibrium vapor nucleation

A brief survey of computerized expert systems for crop protection being used in India

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Progress in Natural Science:Materials International 2008年第4期18卷 469-473页

作者： Pinaki Chakraborty dilip Kumar Chakrabarti School of Computer and Systems Sciences Jawaharlal Nehru University Department of Horticulture Narendra Dev University of Agriculture and Technology

In the recent years, a plethora of computerized expert systems has been developed for various sectors of agriculture in India. The availability of low-cost computers, agricultural knowledge and information technology professionals are the principal reasons for the development of so many agricultural expert systems. Among all agricultural expert systems, the expert systems for crop protection need special mention. These expert systems are meant to be used by farmers and other persons without much experience of using computers. Hence, special care must be taken while developing them. The current paper develops a taxonomy for the expert systems for crop pro- tection and briefly discusses four such expert systems for crop protection being used in India.

关键词： Computerized expert system Agriculture Agricultural expert system Crop protection