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Scattering of water waves by thick rectangular barriers in presence of ice cover

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Journal of Ocean Engineering and Science 2020年第3期5卷 279-293页

作者： Anushree Samanta rumpa chakraborty Department of Mathematics Jadavpur UniversityKolkata-700032India Department of Mathematics Diamond Harbour Women’s UniversitySouth 24 Parganas-743368India

Assuming linear theory,the two dimensional problem of water wave scattering past thick rectangular barrier in presence of thin ice cover,is investigated *** four types of thick barriers are considered here and also the ice cover is taken as a thin elastic *** be the barrier is partially immersed or bottom standing or fully submerged in water or in the form of thick rectangular wall with a submerged gap presence in *** problem is formulated in terms of a first kind integral equation by considering the symmetric and antisymmetric parts of velocity potential *** integral equation is solved by using multi term Galerkin approximation method involving ultraspherical Gegenbauer polynomials as its basis *** numerical solutions of reflection and transmission coefficients are obtained for different parametric values and these are seen to satisfy the energy *** coefficients are depicted graphically against the wave number in a number of *** figures available in the literature drawn by using different mathematical methods as well as laboratory experiments are also recovered following the present analysis without the presence of ice cover,thereby confirming the correctness of the results presented *** is also observed that the reflection and transmission coefficients depend significantly on the width of the barriers.

关键词： Rectangular thick barrier Ice cover Water wave scattering Multi term Galerkin approximation technique Reflection and transmission coefficients

Gravity Wave Generated by Initial Axisymmetric Disturbance at the Surface of an Ice‑covered Ocean with Porous Bed

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Journal of Marine Science and Application 2021年第4期20卷 632-645页

作者： Piyali Kundu rumpa chakraborty Department of Science&Humanities North CalcuttaPolytechnicCossiporeKolkata 700002India Department of Mathematics Diamond Harbour Women’sUniversitySouth 24 Parganas Pin-743368 SarishaIndia

This paper is concerned with the generation of gravity waves due to prescribed initial axisymmetric disturbances created at the surface of an ice sheet covering the ocean with a porous *** ice cover is modeled as a thin elastic plate,and the bottom porosity is described by a real *** linear theory,the problem is formulated as an initial value problem for the velocity potential describing the *** the mathematical analysis,the Laplace and Hankel transform techniques have been used to obtain the depression of the ice-covered surface in the form of a multiple infnite *** integral is evaluated asymptotically by the method of stationary phase twice for a long time and a large distance from the *** numerical computations are performed to illustrate the efect of the ice-covered surface and bottom porosity on the surface elevation,phase velocity,and group velocity of the surface gravity *** the far-feld behavior of the progressive waves is observed in two diferent cases,namely initial depression and an impulse concentrated at the *** graphical representations,it is clearly visible that the presence of ice cover and a porous bottom decreases the wave *** to the porous bottom,the amplitude of phase velocity decreases,whereas the amplitude of group velocity increases.

关键词： Axisymmetric disturbances and ice-covered ocean Porous bottom Laplace and Hankel transform Method of stationary phase Free surface depression Phase velocity and group velocity

Water Wave Scattering by a Nearly Circular Cylinder Submerged Beneath an Ice-cover

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Journal of Marine Science and Application 2015年第1期14卷 69-75页

作者： rumpa chakraborty Birendra Nath Mandal Physics and Applied Mathematics Unit Indian Statistical Institute Kolkata 700108 India

Assuming linear theory, the two-dimensional problem of water wave scattering by a horizontal nearly circular cylinder submerged in infinitely deep water with an ice cover modeled as a thin-elastic plate floating on water, is investigated here. The cross-section of the nearly circular cylinder is taken as r=a（1＋δC（θ））, where a is the radius of the corresponding circular cross-section of the cylinder, δ is a measure of small departure of the cross-section of the cylinder from its circularity and C（θ） is the shape function. Using a simplified perturbation technique the problem is reduced to two independent boundary value problems up to first order in δ. The first one corresponds to water wave scattering by a circular cylinder submerged in water with an ice-cover, while the second problem describes wave radiation by a submerged circular cylinder and involves first order correction to the reflection and transmission coefficients. The corrections are obtained in terms of integrals involving the shape function. Assuming a general Fourier expansion of the shape function, these corrections are evaluated approximately. It is well known that normally incident wave trains experience no reflection by a circular cylinder submerged in infinitely deep water with an ice cover. It is shown here that the reflection coefficient also vanishes up to first order for some particular choice of the shape function representing a nearly circular cylinder. For these cases, full transmission occurs, only change is in its phase which is depicted graphically against the wave number in a number of figures and appropriate conclusions are drawn.

关键词： water wave scattering ice-cover nearly circular cylinder shape function reflection coefficient transmission coefficient

Water Wave Scattering by an Elastic Thin Vertical Plate Submerged in Finite Depth Water

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Journal of Marine Science and Application 2013年第4期12卷 393-399页

作者： rumpa chakraborty B. N. Mandal Physics and Applied Mathematics Unit Indian Statistical Institute

The problem of water wave scattering by a thin vertical elastic plate submerged in uniform finite depth water is investigated *** boundary condition on the elastic plate is derived from the Bernoulli-Euler equation of motion satisfied by the *** the Green’s function technique,from this boundary condition,the normal velocity of the plate is expressed in terms of the difference between the velocity potentials(unknown)across the *** two ends of the plate are either clamped or *** reflection and transmission coefficients are obtained in terms of the integrals’involving combinations of the unknown velocity potential on the two sides of the plate,which satisfy three simultaneous integral equations and are solved *** coefficients are computed numerically for various values of different parameters and depicted graphically against the wave number in a number of figures.

关键词： thin vertical elastic plate uniform finite depth water wave scattering reflection and transmission coefficients

Effect of eccentric and inclined loading on the bearing capacity of strip footing placed on rock mass

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Journal of Mountain Science 2024年第1期21卷 292-312页

作者： Shuvankar DAS Debarghya chakraborty Department of Civil Engineering Indian Institute of Technology KharagpurWest Bengal-721302India

This paper deals with the bearing capacity determination of strip footing on a rock mass in hilly area by considering the influence of inclined and eccentric loading. Applying the generalized HoekBrown failure criterion, the failure behavior of the rock mass is modeled with the help of the power cone programming in the lower bound finite element limit analysis framework. Using bearing capacity factor(Ns), the change in bearing capacity of the strip footing due to the occurrence of eccentrically inclined loading is presented. The variations of the magnitude of Ns are obtained by examining the effects of the Hoek-Brown rock mass strength parameters(uniaxial compressive strength(sci), disturbance factor(D), rock parameter(mi), and Geological Strength Index(GSI)) in the presence of different magnitudes of eccentricity(e) and inclination angle(λ) with respect to the vertical plane, and presented as design charts. Both the inclined loading modes, i.e., inclination towards the center of strip footing(+λ) and inclination away from the center of strip footing(-λ), are adopted to perform the investigation. In addition, the correlation between the input parameters and the corresponding output is developed by utilizing the artificial neural network(ANN). Additionally, from sensitivity analysis, it is observed that inclination angle(λ) is the most sensitive parameter. For practicing engineers, the obtained design equation and design charts can be beneficial to understand the bearing capacity variation in the existence of eccentrically inclined loading in mountain areas.

关键词： Eccentric and inclined Power cone programming Rock mass Limit analysis Artificial neural network

Balancing machine learning and artificial intelligence in soil science with human perspective and experience

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Pedosphere 2024年第1期34卷 9-12页

作者： David C.WEINDORF Somsubhra chakraborty Department of Earth and Atmospheric Science Central Michigan Universityount Pleasant M148859USA Agricultural and Food Engineering Department Indian Institute of TechnologyKharagpur 721302India

Machine learning and artificial intelligence continue to evolve at a rapid pace, with many potential applications related to soil science. Even so, human experience and perception play an invaluable role in characterizing soil properties, especially qualitative properties that may elude sensing/computer-based modeling approaches. The elegant solution to this conundrum relies on the synthesis of computer-aided predictive modeling with human insight and *** global population surpasses 8 billion, the importance of optimized agronomic production to feed a hungry world has never been more important.

关键词： soil elude qualitative

Dynamics of a delay-induced prey-predator system with interaction between immature prey and predators

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International Journal of Biomathematics 2024年第2期17卷 139-176页

作者： Soumik Pandey Abhijit Sarkar Debashis Das Sarbani chakraborty Department of Mathematics West Bengal State University Barasat-7000126West BengalIndia Department of Basic Science&Humanities JIS College of Engineering Kalyani-741235West BengalIndia

In biological pest control systems,several pests(including insects,mites,weeds,etc.)are controlled by biocontrol agents that rely primarily on *** this biocontrol management ecology,we have created a three-tier prey-predator model with prey phase structure and predator gestation *** studies have demonstrated that predators with Holling type-II functional responses sometimes consume immature prey.A study of the well-posedness and local bifurcation(such as saddle-node and transcritical)near the trivial and planer equilibrium points is carried *** any time lag,the prey development coeficient has a stabilizing impact,while increasing attack rate accelerates *** transformation rate and handling time are shown to cause multiple stability switches in the *** results demonstrate time delay is the key destabilizer that destroys *** model can replicate more realistic events by including time-dependent factors and exploring the dynamic behavior of nonautonomous *** the presence of time delay,sufficient conditions of permanence and global attractivity of the nonautonomous system are ***,MATLAB simulations are performed to validate the analytical findings.

关键词： Holling type-II functional response stage-structure bifurcation time delay seasonality

Combinations of electron and proton donors in transition-metal complex mediated nitrogen reduction reactions

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Science China Chemistry 2024年第7期67卷 2136-2154页

作者： Delong Han Li Yang Hao Huang Priyanka chakraborty Shashikant U.Dighe Kuo-Wei Huang KAUST Catalysis Center and Division of Physical Science and Engineering King Abdullah University of Science and TechnologyThuwal 23955Saudi Arabia Agency for Science Technologyand ResearchInstitute of Materials Research and Engineering and Institute of Sustainability for ChemicalsEnergy and EnvironmentSingapore 138634Singapore

Nitrogen fixation is a complex process involving the transfer of six electrons and *** from the conventional Haber-Bosch process,which relies on hydrogen(H_(2))to provide both electrons and protons to reduce nitrogen(N_(2)),homogeneous transition metal complex-catalyzed N_(2)reduction reactions(NRR)employ an array of electron and proton donors or even electron donors combined with *** the synthesis of diverse catalytic progress,the categories of donors have seen rapid ***,existing literature only provides summaries regarding the metal,ligands,and *** the significance of electron and proton donor combinations in nitrogen reduction reactions,no literature has thoroughly reviewed this ***,we hereby compiled a comprehensive list of commonly used reagents in N_(2)reduction and classified them according to their specific donor *** review presents clear and organized information about these combinations,along with a summary of their general performance trend in NRR with related ***,we conclude the discussion by highlighting key points for researchers to consider when selecting catalysts and donor combinations,with the ultimate goal of advancing the field of nitrogen fixation.

关键词： dinitrogen reduction reaction reducing donor combination transition metal complexes homogeneous catalysis

An Autopsy and Histopathology-based Study to Ascertain the Cause of Death of Brought Dead Cases

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Journal of Forensic Science and Medicine 2024年第1期10卷 28-33页

作者： Chandan Bandyopadhyay Prabir Chandra Paul Prabhas Chandra chakraborty Department of Forensic and State Medicine Medical CollegeKolkataWest BengalIndia Department of Pathology Jagannath Gupta Institute of Medical Science and HospitalKolkataWest BengalIndia Department of Forensic Medicine and Toxicology NRS Medical College and HospitalKolkataand M.G.M Medical College and L S.K HospitalKishanganjBiharIndia

Background and Objectives:The cases of apparent natural deaths are encountered in the hospital casualties who are noted dead at the time of the first medical attention and as such are labeled as“Brought Dead.”These include the cases of sudden death,unexplained death,and unattended *** cause of such deaths is reported in the literature to emanate principally from the cardiovascular system,though there are some documented geographical,racial,and other *** the present study,we endeavored to detect the cause of such natural deaths in terms of the disease and the organ system involved,in the deceased individuals of the contemporary Bengali population,with cases due to obvious unnatural causes being *** and Methods:An observational,cross-sectional study with 105(n=105,male:89,female:16)study subjects of age group of 20-80 years,selected by systemic random sampling,from the brought dead subjects coming to the mortuary of the NRS Medical College and Hospital for medicolegal autopsy from April 2011 to March 2012,excluding cases having a history of the obvious unnatural *** system-wise gross examination was done,followed by tissue sampling for histopathological *** case-wise findings were tabulated and analyzed for descriptive statistics using SPSS ***:In the present study,89 cases were male(84.8%)and 16 cases were female(15.2%),which reflects a male:female ratio of 5.56:*** dead bodies are mostly recovered from the footpaths(47 cases,44%).Sixty-four(61%)cases are of known *** 54 cases out of 105(51.4%),morbid pathology is detected in the respiratory system(RS),lobar pneumonia,and cavitary pulmonary tuberculosis being the most frequent disease entity,in both ***-one years-sixty-five years is found to be the most commonly affected age group,in both *** and Conclusions:The present study shows that the most common organ system involved in brought dead cases is the RS,which is s

关键词： Autopsy brought dead cause of death histopathology