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Jeans Instability of Self Gravitating Dust Cloud in Presence of Effective Electrostatic Pressure

2006年

作者： Satyajit das.

来源：畅想之星图书光盘版（南... 评论

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Communications in Theoretical Physics 2018年第8期69卷 209-214页

作者： Pratikshya Bezbaruah Pritam das Prathana Borah Nilakshi das Department of Physics Tezpur University

The role of viscosity coefficient(η′), coulomb coupling parameter(Γ) and dust mass on the growth of jeans mode is investigated in strongly coupled dusty plasma using equations of Generalized Hydrodynamics(GH) Model. The novel aspect of this work is that the force arising due to electrostatic pressure caused by grain grain interaction has been included in the dynamics of dust particles. This force is found to play a significant role in counter balancing the self gravity effect, thereby reducing the growth rate of jeans instability. The present work may provide more physical insight in understanding the mechanisms behind formation of planetesimals, stars etc.

关键词： generalized hydrodynamics model interstellar medium planetesimal

Sum-connectivity index of a graph

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Frontiers of Mathematics in China 2016年第1期11卷 47-54页

作者： Kinkar Ch. das Sumana das Bo ZHOU Department of Mathematics Sungkyunkwan University Suwon 440-746 Korea School of Information and Communication Engineering Sungkyunkwan UniversitySuwon 440-746 Korea Department of Mathematics South China Normal University Guangzhou 510631 China

Let G be a simple connected graph, and let di be the degree of its i-th vertex. The sure,connectivity index of the graph G is defined as χ（G） =∑vivj∈E（G）（di＋dj）-1/*** discuss the effect onχ（G）of inserting... 详细信息

关键词： Graph Randid index sum-connectivity index minimum degree

Multi-criteria decision based geospatial mapping of flood susceptibility and temporal hydro-geomorphic changes in the Subarnarekha basin, India

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Geoscience Frontiers 2021年第5期12卷 327-341页

作者： Sumit das Amitesh Gupta Department of Geography Savitribai Phule Pune UniversityPune 411007India Marine and Atmospheric Science Department Indian Institute of Remote Sensing(ISRO)DehradunIndia Department of Remote Sensing and GIS JIS UniversityKolkataIndia

The Subarnarekha River in east India experiences frequent high magnitude flooding in monsoon *** this study,we present an in-depth analysis of flood hydrology and GIS-based flood susceptibility mapping of the entire *** 40 years of annual peak discharge data,historical cross-sections of different gauging sites,and 12 flood conditioning factors were *** flood susceptibility mapping followed an expert knowledge-based multi-parametric analytical hierarchy process(AHP)and optimized AHP-VIP *** hydrology data indicated more than 5 times higher discharge contrasted with the mean streamflow of the peak monsoon month in all hydro-monitoring stations that correspond to possible overbank flooding in the shallow semi-alluvial reaches of the Subarnarekha *** ratio revealed continuous changes on the channel cross-sections at decadal scale in all gauging *** flood susceptibility map through optimized AHP-VIP method showed a great amount of areas(38%)have a high probability of flooding and demands earnest attention of administrative *** AHP-VIP based flood susceptibility map was theoritically validated through AUC approach and it showed fairly high accuracy(AUC=0.93).Our study offers an exceptionally cost and time effective solution to the flooding issues in the Subarnarekha basin.

关键词： Flood susceptibility AHP GIS Discharge Subarnarekha India

Can we constrain the evolution of HI bias using configuration entropy?

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Research in Astronomy and Astrophysics 2021年第2期21卷 82-88页

作者： Biswajit das Biswajit Pandey Department of Physics Visva-Bharati UniversitySantiniketanBirbhum731235India

We study the evolution of the configuration entropy of HI distribution in the post-reionization era assuming different time evolution of HI *** describe time evolution of linear bias of HI distribution using a simple form b(a)=b_(0)a^(n) with different index *** derivative of the configuration entropy rate is known to exhibit a peak at the scale factor corresponding to theΛ-matter equality in the unbiasedΛCDM *** show that in theΛCDM model with time-dependent linear bias,the peak shifts to smaller scale factors for negative values of *** is related to the fact that the growth of structures in the HI density field can significantly slow down even before the onset ofΛdomination in the presence of a strong time evolution of the HI *** find that the shift is linearly related to the index *** obtain the best fit relation between these two parameters and propose that identifying the location of this peak from observations would allow us to constrain the time evolution of HI bias within the framework of theΛCDM model.

关键词： methods analytical-cosmology theory-large scale structure of the universe

BIST Design for Detecting Multiple Stuck—Open Faults in CMOS Circuits Using Transition Count

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Journal of Computer Science & Technology 2002年第6期17卷 731-737页

作者： HafizurRahaman DebeshK.das 等 IndianInstituteofInformationTechnology Calcutta－700106India DepartmentofComputerScienceandEngineering JadavpurUniversityCalcutta－700032India

This paper presents a built-in self-test (BIST) scheme for detecting allrobustly testable multiple stuck-open faults confined to any single complex cell of a CMOS *** test pattern generator (TPG) generates all n·2~n single-input-change (SIC) ordered test pairsfor an n-input circuit-under-test (CUT) contained in a sequence of length 2n·2~n. The proposeddesign is universal, i.e., independent of the structure and functionality of the CUT. A counter thatcounts the number of alternate transitions at the output of the CUT, is used as a signatureanalyzer (SA). The design of TPG and SA is simple and no special design-or synthesis-for-testabilitytechniques and/or additional control lines are needed.

关键词： BIST CMOS complex cell stuck-open faults testing TPG

Hydrogeochemical characteristics and its role in controlling arsenic mobilization in a shallow aquifer

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Acta Geochimica 2021年第6期40卷 912-925页

作者： Ayan das Abhijit Mandal Department of Chemistry University of KalyaniKalyaniWest BengalIndia Department of General Science and Humanities GKCIETMaldaWest BengalIndia

The relevance of groundwater hydrogeochemistry to explain the occurrence and distribution of arsenic in groundwater is of great *** insightful discussions on the control of shallow groundwater(<50 m)hydrogeochemistry in arsenic mobilization are known to be a viable tool to explain the arsenic menace in shallow *** present investigation emphasizes the hydrogeochemical driver and/or control over the reductive dissolution of Fe-bearing host minerals and thereby releasing arsenic into the shallow groundwater of the study *** study suggests that hydrogeochemical evolution is mainly governed by carbonate minerals dissolution,silicate weathering,and competitive ion-exchange processes in the shallow aquifers(<50 m).The present study also indicates the prevalence of carbonate minerals dissolution over silicate *** emergence of Cl^(-)concentration in the shallow groundwater founds the possibilities of anthropogenic inputs into the shallow aquifers(<50 m).The reducing environment in shallow aquifers(<50 m)of the study area is evident in the reductive dissolution of Febearing shallow aquifer minerals which absorb arsenic in the solid phase and mobilize arsenic onto shallow *** study opted for many statistical approaches to delineate the correlation among major and minor ionic constituents of the groundwater which are very helpful to understand the comprehensive mechanism of arsenic mobilization into shallow groundwater.

关键词： Arsenic mobilization Groundwater hydrogeochemistry Aquifer sediments Shallow aquifers Redox environment

Milky Way globular cluster dynamics:are they preferentially co-rotating?

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Research in Astronomy and Astrophysics 2020年第8期20卷 280-286页

作者： Saikat das Nirupam Roy Astronomy&Astrophysics Group Raman Research InstituteBangalore 560080India Department of Physics Indian Institute of ScienceBangalore 560012India

The motion of baryonic components of the Milky Way is governed by both luminous and dark matter content of the ***,the dynamics of Milky Way globular clusters(GCs)can be used as tracers to infer the mass model of the Galaxy up to a large *** this work,we apply the directly observable line-of-sight velocities to test if the dynamics of the GC population are consistent with an assumed axisymmetric gravitational potential of the Milky *** this,we numerically compute the phase space distribution of the GC population where the orbits are either oriented randomly or co-/counter-rotating with respect to the stellar *** we compare the observed position and line-of-sight velocity distribution of^150 GCs with those of the *** found that,for the adopted mass model,the co-rotating scenario is the favored model based on various statistical *** do the analysis with and without the GCs associated with the progenitors of early merger *** analysis can be extended in the near future to include precise and copious data to better constrain the Galactic potential up to a large radius.

关键词： Galaxy:kinematics and dynamics globular clusters:general galaxies:dwarf Galaxy:halo methods:statistical

Diet of Juvenile Crocodylus porosus at Kuching Wetlands National Park,Sarawak,East Malaysia

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Asian Herpetological Research 2021年第3期12卷 323-330页

作者： ENGKAMAT LADING INDRANEIL das Sarawak Forest Department Wisma Sumber AlamPetra Jaya 93660SarawakMalaysia Institute of Biodiversity and Environmental Conservation Universiti Malaysia SarawakKota Samarahan 94300SarawakMalaysia

The diet of juvenile,including hatchlings and presumed yearlings of the Saltwater Crocodile,Crocodylus porosus,was studied at the Kuching Wetlands National Park,western Sarawak,East Malaysia(Borneo),using both frequency of occurrence and volumetric composition of diet through the stomach flushing *** form the primary component of the diet of juvenile crocodiles,comprising shrimps of the family Atyidae(Caridina sp.,and Penaeus indicus),occurring in the stomach of 17 individuals(53%by occurrence).An estimated 91.7%of hatchlings stomach-flushed had shrimps,and the emergence of hatchlings may be associated by inland migration of its shellfish prey,as reported in the *** secondary food item of hatchlings and presumed yearlings was ocypodid crabs,occurring in 16 individuals(in addition to a subadult),and comprise 47%-50%by *** items taken incidentally include rodents(in large yearlings,exceeding 100 cm in total length),and fish(in seven hatchlings and in one subadult),or in 29%of total individuals captured(47.7%in hatchlings and 15%in yearlings).A dietary change in ontogeny is therefore evident,as reported earlier in crocodilians.

关键词： saltwater crocodile Crocod ylus porosus food ecology Borneo

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