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Variations of the harmonic components of the X-ray pulse profile of PSR B1509–58

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Research in Astronomy and Astrophysics 2015年第1期15卷 28-36页

作者： Pragati Pradhan Biswajit paul Harsha Raichur bikash chandra paul St Joseph’s College Singamari Darjeeling 734104 West Bengal India North Bengal University Raja Rammohanpur District Darjeeling 734013 West Bengal India Raman Research Institute Sadashivnagar Bangalore 560080 India

We used the Fourier decomposition technique to investigate the stability of the X-ray pulse profile of a young pulsar PSR B1509–58 by studying the relative amplitudes and phase differences of its harmonic components with respect to the fundamental using data from the Rossi X-Ray Timing Explorer. Like most young rotation powered pulsars, PSR B1509–58 has a high spin down rate. It also has less timing noise, allowing accurate measurement of higher order frequency derivatives which in turn helps in the study of the physics of pulsar spin down. Detailed investigation of pulse profiles over the years will help us establish any possible connection between the timing characteristics and the high energy emission characteristics for this ***, the study of pulse profiles of short period X-ray pulsars can also be useful when used as a means of interplanetary navigation. The X-ray pulse profile of this source has been analyzed for 15 yr（1996–2011）. The long term average amplitudes of the first, second and third harmonics（and their standard deviation for individual measurements） compared to the fundamental are 36.9%（1.7%）, 13.4%（1.9%） and 9.4%（1.8%） respectively. Similarly, the phases of the three harmonics（and standard deviations） with respect to the fundamental are 0.36（0.06）, 1.5（0.2） and 2.5（0.3） radian respectively. We do not find any significant variation of the harmonic components of the pulse profile in comparison to the fundamental.

关键词： pulsars: individual:(PSR B1509–58) stars: neutron X-rays

Tectonic control on the drainage system in a piedmont region in tectonically active eastern Himalayas

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Frontiers of Earth Science 2012年第1期6卷 29-38页

作者： Chandreyee GOSWAMI Dhruba MUKHOPADHYAY bikash chandra PODDAR Asutosh College Saltlake CityKolkata 700026India Raman Center for Applied and Interdisciplinary Sciences Saltlake CityKolkata 700075India BE 267 Saltlake CityKolkata 700064India

The impact ofneotectonic activity on drainage system has been studied in a large alluvial fan in the eastern Himalayan piedmont area between the Mal River and the Murti River. Two distinct E-W lineaments passing through this area had been identified by Nakata （1972, 1989） as active faults. The northern lineament manifested as Matiali scarp and the southern one manifested as Chalsa scarp represent the ramp anticlines over two blind faults, probably the Main Boundary Thrust （MBT） and the Himalayan Frontal Thrust （HFT）, respectively. The fan surface is folded into two antiforms with a synform in between. These folds are interpreted as fault propagation folds over the two north dipping blind thrusts. Two lineaments trending NNE-SSW and nearly N-S, respec- tively, are identified, and parts of present day courses of the Murti and Neora Rivers follow them. These lineaments are named as Murti and Neora lineaments and are interpreted to represent a conjugate set of normal faults. The rivers have changed their courses by the influence of these normal faults along the Murti and Neora lineaments and their profiles show knick points where they cross E-W thrusts. The overall drainage pattern is changed from radial pattern in north of the Matiali scarp to a subparallel one in south due to these conjugate normal faults. The interfluve area between these two rivers is uplifted as a result of vertical movements on the above mentioned faults. Four major terraces and some minor terraces are present along the major river valleys and these are formed due to episodic upliftment of the ground and subsequent down- cutting of the rivers. The uppermost terrace shows a northerly slope north of the Chalsa scarp as a result of folding mentioned above. But rivers on this terrace form incised channels keeping their flow southerly suggestingthat they are antecedent to the folding and their downcutting kept pace with the tectonism.

关键词： alluvial fan drainage pattern thrust normalfault active tectonic

An Efficient Approach for Simulation of Water Levels due to the Nonlinear Interaction of Tide and Surge Along the Coast of Bangladesh

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China Ocean Engineering 2020年第4期34卷 537-546页

作者： Gour chandra paul Sukumar Senthilkumar Rana Pria Department of Mathematics University of RajshahiRajshahi-6205Bangladesh School of Mathematical Sciences Universiti Sains MalaysiaPulau Pinang-11800Malaysia Mathematics Discipline ScienceEngineering&Technology SchoolKhulna UniversityKhulna-9208.Bangladesh

The ultimate goal and highlight of this paper are to explore water levels along the coast of Bangladesh efficiently due to the nonlinear interaction of tide and surge by employing the method of lines(MOLs)with the aid of newly proposed RKAHeM(4,4)*** this regard,the spatial derivatives of shallow water equations(SWEs)were discretized by means of a finite difference method to obtain a system of ordinary differential equations(ODEs)of initial valued with time as an independent *** obtained system of ODEs was solved by the RKAHeM(4,4)***-way nested grid technique was exercised to incorporate coastal complexities closely with minimum computational cost.A stable tidal oscillation was produced over the region of interest by applying the most influential tidal constituent M2 along the southern open boundary of the outer *** newly developed model was applied to estimate water levels due to the non-linear interaction of tide and surge associated with the catastrophic cyclone April 1991 along the coast of *** approach employed in the study was found to perform well and ensure conformity with real-time observations.

关键词： method of lines RKAHeM(4 4)technique error estimation storm surge nested grid

Environmental Arsenic and Selenium Contamination and Approaches Towards Its Bioremediation Through the Exploration of Microbial Adaptations:A Review

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Pedosphere 2019年第5期29卷 554-568页

作者： Tanmoy paul Nimai chandra SAHA National Institute of Cholera and Enteric Diseases Kolkata 700010 (India) Fishery and Ecotoxicology Research Laboratory (Vice-Chancellor}s Research Group) Department of ZoologyThe University of BurdwanBurdwan 713104 (India)

Bioaccumulation of selenium and arsenic resulting from geogenic activities and aggravated by anthropogenic actions has now become a serious environmental issue. Different parts of the world are experiencing issues of selenium and arsenic contamination, especially in soil and ground water. The present selenium and arsenic contamination scenario has been well represented in contemporary literature, and there are an array of remediation techniques targeting the decontamination of environmental contamination. The use of microbe-mediated remediation of selenium and arsenic contamination is gaining scientific attention for sustainable environmental bioremediation. The present review elucidates the different aspects of selenium and arsenic contamination, bioaccumulation, and bioremediation with implications for successful decontamination of these heavy metals.

关键词： bioaccumulation biogeochemistry chemical species contaminant decontamination heavy metal microbial remediation microorganism

Nanoscale cryptographic architecture design using quantum-dot cellular automata

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Frontiers of Information Technology & Electronic Engineering 2019年第11期20卷 1578-1586页

作者： bikash DEBNATH Jadav chandra DAS Debashis DE Department of Computer Science and Engineering Swami Vivekananda Institute of Science and TechnologyWest Bengal 700145India Department of Computer Science and Engineering West Bengal University of TechnologyKolkata 700064India

Quantum-dot cellular automata (QCA) based on cryptography is a new paradigm in the field of nanotechnology. The overall performance of QCA is high compared to traditional complementary metal-oxide semiconductor (CMOS) technology. To achieve data security during nanocommunication, a cryptography-based application is proposed. The devised circuit encrypts the input data and passes it to an output channel through a nanorouter cum data path selector, where the data is decrypted back to its original form. The results along with theoretical implication prove the accuracy of the circuit. Power dissipation and circuit complexity of the circuit have been analyzed.

关键词： Quantum-dot cellular automata(QCA) Majority gate cryptography Encryption Decryption Nanorouter

An Efficient Tide-Surge Interaction Model for the Coast of Bangladesh

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China Ocean Engineering 2020年第1期34卷 56-68页

作者： M.Mizanur RAHMAN Gour chandra paul Ashabul HOQUE Department of Mathematics Shahjalal University of Science&TechnologySylhet 3114Bangladesh Department of Mathematics University of RajshahiRajshahi-6205Bangladesh

The numerical method of lines(MOLs)in coordination with the classical fourth-order Runge Kutta(RK(4,4))method is used to solve shallow water equations(SWEs)for foreseeing water levels owing to the nonlinear interaction of tide and surge accompanying with a storm along the coast of *** SWEs are developed by extending the body forces with tide generating forces(TGFs).Spatial variables of the SWEs along with the boundary conditions are approximated by means of finite difference technique on an Arakawa C-grid to attain a system of ordinary differential equations(ODEs)of initial valued in time,which are being solved with the aid of the RK(4,4)*** grid technique is adopted to solve coastal complexities closely with least computational cost.A stable tidal solution in the region of our choice is produced by applying the tidal forcing with the major tidal constituent M2(lunar semi-diurnal)along the southern open-sea boundary of the outer *** experimentations are carried out to simulate water levels generated by the cyclonic storm AILA along the coast of *** model simulated results are found to be in a reasonable agreement with the limited available reported data and observations.

关键词： Bangladesh coast shallow water equations method of lines tide-surge interaction islands tide generating forces inverse barometer

Storm surge simulation along the Meghna estuarine area:an alternative approach

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Acta Oceanologica Sinica 2018年第1期37卷 40-49页

作者： paul Gour chandra SENTHILKUMAR Sukumar PRIA Rana Department of Mathematics University of Rajshahi School of Mathematical Sciences Universiti Sains Malaysia Mathematics Discipline Khulna University

In this study, numerical prediction of surges associated with a storm was made through the method of lines（MOL） in coordination with the newly proposed RKARMS（4, 4） method for the meghna estuarine region, along the coast of Bangladesh. For this purpose, the vertically integrated shallow water equations（SWEs） in Cartesian coordinates were firstly transformed into ordinary differential equations（ODEs） of initial valued, which were then soloved using the new RKARMS（4, 4） method. Nested grid technique was employed for resolving the complexities of the region of interest with minimum cost. Fresh water discharge through the lower Meghna River was taken into account along the north east corner of the innermost child scheme. Numerical experiments were performed with the severe cyclone on April 1991 that crossed the coast over the study area. Simulated results by the study were found to be in good agreement with some reported data and were found to compare well with the results obtained by the MOL in addition with the classical 4th order Runge-Kutta（RK（4, 4）） method and the standard finite difference method（FDM）.

关键词： method of lines storm surge nested grid finite difference method RKARMS (4, 4) method truncation errors

Numerical storm surge model with higher order finite difference method of lines for the coast of Bangladesh

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Acta Oceanologica Sinica 2019年第6期38卷 100-116页

作者： Gour chandra paul Md. Emran Ali Department of Mathematics University of RajshahiRajshahi 6205Bangladesh Department of Textile Engineering Northern University BangladeshDhaka 1230Bangladesh

In this study, the method of lines (MOLs) with higher order central difference approximation method coupled with the classical fourth order Runge-Kutta (RK(4,4)) method is used in solving shallow water equations (SWEs) in Cartesian coordinates to foresee water levels associated with a storm accurately along the coast of Bangladesh. In doing so, the partial derivatives of the SWEs with respect to the space variables were discretized with 5-point central difference, as a test case, to obtain a system of ordinary differential equations with time as an independent variable for every spatial grid point, which with initial conditions were solved by the RK(4,4) method. The complex land-sea interface and bottom topographic details were incorporated closely using nested schemes. The coastal and island boundaries were rectangularized through proper stair step representation, and the storing positions of the scalar and momentum variables were specified according to the rules of structured C-grid. A stable tidal regime was made over the model domain considering the effect of the major tidal constituent, M2 along the southern open boundary of the outermost parent scheme. The Meghna River fresh water discharge was taken into account for the inner most child scheme. To take into account the dynamic interaction of tide and surge, the generated tidal regime was introduced as the initial state of the sea, and the surge was then made to come over it through computer simulation. Numerical experiments were performed with the cyclone April 1991 to simulate water levels due to tide, surge, and their interaction at different stations along the coast of Bangladesh. Our computed results were found to compare reasonable well with the limited observed data obtained from Bangladesh Inland Water Transport Authority (BIWTA) and were found to be better in comparison with the results obtained through the regular finite difference method and the 3-point central difference MOLs coupled with the RK(4,

关键词： shallow water equations method of lines higher order finite difference approximation method surge nested scheme

Dietary experience alters predatory behavior of two ladybird species on tomato potato psyllid

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Insect Science 2024年第5期31卷 1579-1590页

作者： Shovon chandra Sarkar Stephen paul Milroy Wei Xu Food Futures Institute Murdoch UniversityMurdochWestern AustraliaAustralia

The tomato potato psyllid,Bactericera cockerelli,is an invasive pest in Aus-tralia,which can cause severe economic loss in the production of Solanaceous *** an invasive pest,*** may also modify biotic interactions in Australian agricul-tural and native *** generalist predators in an area may have the ability to utilize invasive pest species as prey but this will depend on their specific predatory *** extent to which generalist predators learn from their previous dietary ex-perience(i.e.,whether they have used a particular species as prey before)and how this impacts subsequent prey choice will influence predator and prey population dynamics af-ter *** this study,one nonnative resident ladybird,Hippodamia variegata,and one native ladybird,Coccinella transversalis,were *** experience with *** as a prey species significantly increased preference for the psyllid in a short term(6 h)Petri dish study where a choice of prey was *** suppression of *** populations by experienced ladybirds was also observed on glasshouse grown tomato *** was presumably due to altered prey recognition by *** result of this study suggest the potential to improve the impact of biological control agents on invasive pests by providing early life experience consuming the target *** may prove valuable for developing improved augmentative release strategies for ladybirds to manage specific insect pest species.

关键词： biological control invasive pest predator predator experience prey prefer-ence