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Wyszukujesz frazę "Roy, S. K." wg kryterium: Autor

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    Wyświetlanie 1-12 z 12
    Tytuł:
    Bright Solitons in Asymmetrically Trapped Bose-Einstein Condensates
    Autorzy:
    Golam Ali, Sk.
    Talukdar, B.
    Roy, S. K.
    Powiązania:
    https://bibliotekanauki.pl/articles/2047288.pdf
    Data publikacji:
    2007-03
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    03.75.-b
    03.75.Kk
    05.30.Jp
    Opis:
    We study the dynamics of bright solitons in a Bose-Einstein condensate confined in a highly asymmetric trap. While working within the framework of a variational approach we carry out the stability analysis of the Bose-Einstein condensate solitons against collapse. When the number of atoms in the soliton exceeds a critical number N$\text{}_{c}$, it undergoes the so-called primary collapse. We find an analytical expression for N$\text{}_{c}$ in terms of appropriate experimental quantities that are used to produce and confine the condensate. We further demonstrate that, in the geometry of the problem considered, the width of the soliton varies inversely as the number of constituent atoms.
    Źródło:
    Acta Physica Polonica A; 2007, 111, 3; 289-297
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    A Green Function Estimation of Correction to Vegards Law for isovalent Substitutional Defects in Alkali Halide Crystals
    Autorzy:
    Datta Roy (Paul), S.
    Das, S. K.
    Powiązania:
    https://bibliotekanauki.pl/articles/2013286.pdf
    Data publikacji:
    2000-04
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    61.72.Bb
    61.82.Bg
    Opis:
    A Green function method is developed for estimation of lattice parameter r(χ) of an AX-BX solid solution over entire composition range (χ=0 to 1). The r(χ) obtained in the present method is different from the value r$\text{}_{V}$(χ) suggested by Vegard's law. We estimated the deviation from Vegard's law, r(χ)-r$\text{}_{V}$(χ), over entire composition range for isovalent substitutional defect in alkali halide crystals. When compared to X-ray diffraction measurements, we find that the deviation is in correct direction, variation of r(χ) with χ is consistent with experiment and the overall agreement is fairly good considering the accuracy of the experiment.
    Źródło:
    Acta Physica Polonica A; 2000, 97, 4; 671-679
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    A comparative study between two systems with and without awareness in controlling HIV/AIDS
    Autorzy:
    Saha, S.
    Roy, P. K.
    Powiązania:
    https://bibliotekanauki.pl/articles/330484.pdf
    Data publikacji:
    2017
    Wydawca:
    Uniwersytet Zielonogórski. Oficyna Wydawnicza
    Tematy:
    epidemic model
    HIV infection
    awareness
    antiretroviral therapy
    basic reproductive number
    numerical simulation
    model epidemiczny
    zakażenie HIV
    świadomość problemu
    terapia antyretrowirusowa
    podstawowy współczynnik reprodukcji
    symulacja komputerowa
    Opis:
    It has always been a priority for all nations to reduce new HIV infections by implementing a comprehensive HIV prevention programme at a sufficient scale. Recently, the ‘HIV counselling & testing’ (HCT) campaign is gaining public attention, where HIV patients are identified through screening and immediately sent under a course of antiretroviral treatment (ART), neglecting the time extent they have been infected. In this article, we study a nonlinear mathematical model for the transmission dynamics of HIV/AIDS system receiving drug treatment along with effective awareness programs through media. Here, we consider two different circumstances: when treatment is only effective and when both treatment and awareness are included. The model is analyzed qualitatively using the stability theory of differential equations. The global stabilities of the equilibria under certain conditions are determined in terms of the model reproduction number. The effects of changes in some key epidemiological parameters are investigated. Projections are made to predict the long term dynamics of the disease. The epidemiological implications of such projections on public health planning and management are discussed. These studies show that the aware populations were less vulnerable to HIV infection than the unaware population.
    Źródło:
    International Journal of Applied Mathematics and Computer Science; 2017, 27, 2; 337-350
    1641-876X
    2083-8492
    Pojawia się w:
    International Journal of Applied Mathematics and Computer Science
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Winter Avian Aggregation at Santragachi Jheel: An Urban Wetland in West Bengal, India
    Autorzy:
    Roy, Utpal Singha
    Mukhopadhyay, S. K.
    Powiązania:
    https://bibliotekanauki.pl/articles/1193635.pdf
    Data publikacji:
    2017
    Wydawca:
    Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
    Tematy:
    Conservation
    Habitat alteration
    Santragachi Jheel
    Waterbirds
    Winter migrants
    Opis:
    India has an estimated 58.2 million hectares of wetlands that are important repositories of aquatic biodiversity. The variety of wetlands in India perfectly matches the diverse eco-climatic regimes of the country. This includes wetland systems ranging from high altitude cold desert wetlands to hot and humid wetlands in coastal zones with its characteristically diverse flora and fauna. Around 15 km away from the center of Kolkata city, West Bengal, lies a 12.77 ha (mean depth 1.5 m) freshwater lake, known as the Santragachi Jheel, in the district of Howrah of West Bengal, India (Lat. 22o 34' 60N Long. 88° 17' 60E; Altitude 8m msl) which has recently attracted the attention of avian migrant watchers India-wide. The Jheel plays an important role as the host of thousands (4000-5000) of migratory water birds as well as many resident species during the colder months of the year (October – March). More than twenty-five bird species colonize this lake during the winter months including the most abundant Lesser Whistling Duck and comparably infrequent Northern Pintail, Northern Shoveller, Gargany, Gadwall, Cotton Pigmy Goose, Common Teal and Baikal Teal. But this urban wetland most recently has been subjected to a wide variety of turbulences that includes incessant anthropogenic activities, improper development and management structures and lack of awareness about the vital role played by this ecosystem. So it was felt important to identify the status of Santragachi Jheel with reference to urbanization and various anthropogenic interventions to formulate suitable conservation, restoration and management strategies for this unique wetland with its magnificent avian repository.
    Źródło:
    World Scientific News; 2017, 71; 191-198
    2392-2192
    Pojawia się w:
    World Scientific News
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Calculation of Lattice Relaxation in Some Substitutional Alloys Using a Green Function
    Autorzy:
    Das, S. K.
    Datta Roy (Paul), S.
    Powiązania:
    https://bibliotekanauki.pl/articles/1995663.pdf
    Data publikacji:
    1999-03
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    61.72.Bb
    61.82.Bg
    Opis:
    In this paper we calculate nearest neighbour relaxation in some dilute substitutional alloys using a lattice static Green function and the Morse potential function. Distant neighbour relaxation is calculated by invoking a continuum approximation. The potential parameters for the unlike interactions are calculated using simple interpolation formulae. Using the above relaxation, we calculate volume changes in the above alloys. It is observed that the simple model predicts values which are in reasonably good agreement with the experimental values in all cases. The calculated values are also compared with those obtained from the Vegard law. For Au-Ag alloy, our model reproduces both the correct sign and the magnitude of the volume change, whereas the Vegard law cannot even give the sign of the volume change. This shows the inherent strength of the present model.
    Źródło:
    Acta Physica Polonica A; 1999, 95, 3; 359-366
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    QSAR modeling for acute toxicity prediction in rat by common painkiller drugs
    Autorzy:
    Roy, J.S.
    Gupta, K.
    Talapatra, S.N.
    Powiązania:
    https://bibliotekanauki.pl/articles/11550.pdf
    Data publikacji:
    2016
    Wydawca:
    Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
    Opis:
    Painkiller drugs or analgesics are potent pain reliever chemical agents, which are commonly used in pain therapy. Mathematical modeling by QSAR (quantitative structure activity relationship) methods are well known practices to determine predictive toxicity in biota. Now-adays, an easy screening of chemicals, QSAR can be done by using several recommended softwares. The present study was carried out by using software namely T.E.S.T. (Toxicity estimation software tool) for rat oral LD50 (median lethal dose) predictive toxicity for common painkiller drugs. These painkiller drugs were selected as 35 compounds and tabulated on the basis characteristics of one non-narcotic viz. acetaminophen, twenty non-steroidal anti-inflammatory such as bromofenac, diclofenac, diflunsial, etodolac, fenoprofen, flurbiprofen, ibuprofen, indomethacin, ketoprofen, ketorolac, maclofenamate sodium, mefenamic acid, meloxicam, nabumetone, naproxen, oxaprozin, phenylbutazone, piroxicam, sulindac and tolmetin as well as fourteen narcotic viz. buprenorphine, butorphanol, codeine, hydrocodone, hydromorphone, levorphanol, meperidine, methadone, morphine, nalbuphine, oxycodone, pentazocine, dextropropoxyphene and tapentadol. The data were tabulated on experimental (bioassay) from ChemIDPlus and T.E.S.T. and predictive toxicity of 30 compounds out of 35 compounds by using T.E.S.T. The predictive data were found by T.E.S.T. that 20 and 10 compounds were very toxic and moderately toxic respectively but not extremely, super toxic and non-toxic in rat model after acute oral exposure. It is suggested to evaluate the predicted data further with other available recommended softwares with different test models like daphnia, fish etc. to know aquatic toxicity when these compounds may discharge into waterbodies.
    Źródło:
    International Letters of Natural Sciences; 2016, 52
    2300-9675
    Pojawia się w:
    International Letters of Natural Sciences
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    A Comparative Ergonomics Postural Assessment of Potters and Sculptors in the Unorganized Sector in West Bengal, India
    Autorzy:
    Sahu, S.
    Moitra, S.
    Maity, S.
    Pandit, A. K.
    Roy, B.
    Powiązania:
    https://bibliotekanauki.pl/articles/89972.pdf
    Data publikacji:
    2013
    Wydawca:
    Centralny Instytut Ochrony Pracy
    Tematy:
    ergonomics
    posture
    musculoskeletal disorders
    low back pain
    REBA
    RULA
    ergonomia
    pozycja przy pracy
    choroby narządów ruchu
    nerwoból okolicy grzbietowej
    Opis:
    Potters and sculptors perform their work in very awkward postures. The purpose of this study was to analyse these postures. The modified Nordic questionnaire was used to analyse musculoskeletal discomfort. Rapid entire body assessment (REBA) and rapid upper limb assessment (RULA) were used to evaluate the subjects' postures. There were no significant differences between times of discomfort and the group of subjects. However, there were significant differences in discomfort in different body parts. The analysis indicated that various body postures were harmful to the subjects and that there were profound deviations from natural curvature of various body parts due to awkward body postures. Ergonomics intervention was required to improve the quality of life.
    Źródło:
    International Journal of Occupational Safety and Ergonomics; 2013, 19, 3; 455-462
    1080-3548
    Pojawia się w:
    International Journal of Occupational Safety and Ergonomics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Mathematical modeling to optimize the product in enzyme kinetics
    Autorzy:
    Nandi, S.
    Ghosh, M. K.
    Bhattacharya, R.
    Roy, P. K.
    Powiązania:
    https://bibliotekanauki.pl/articles/206501.pdf
    Data publikacji:
    2013
    Wydawca:
    Polska Akademia Nauk. Instytut Badań Systemowych PAN
    Tematy:
    enzyme kinetics
    optimization
    optimal control approach
    reversible reaction
    Opis:
    Optimization of product in enzyme kinetics is successful by the showers of mathematical analysis with control measures. Enzymes are an important functional aspects of all biochemical processes, as they catalyze numerous reaction taking place within living organisms. With this view, optimization and quantification of product is stressed upon and in such a context, optimal control approaches have been applied in our study. In this article, we have formulated a mathematical model of enzymatic system Dynamics with control measures with a view to optimize the product as well as process conditions. Here, Pontryagin Minimum Principle is used for determination of optimal control with the help of Hamiltonian. We discuss the relevant numerical solutions for the concentration of substrate, enzyme, complex and product with respect to a specified time interval by varying control factors.
    Źródło:
    Control and Cybernetics; 2013, 42, 2; 431-442
    0324-8569
    Pojawia się w:
    Control and Cybernetics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Impact of Cutting Forces and Chip Microstructure in High Speed Machining of Carbon Fiber - Epoxy Composite Tube
    Autorzy:
    Allwin Roy, Y.
    Gobivel, K.
    Vijay Sekar, K. S.
    Suresh Kumar, S.
    Powiązania:
    https://bibliotekanauki.pl/articles/352953.pdf
    Data publikacji:
    2017
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    composite materials
    orthogonal machining
    cutting forces
    chip microstructure
    Opis:
    Carbon fiber reinforced polymeric (CFRP) composite materials are widely used in aerospace, automobile and biomedical industries due to their high strength to weight ratio, corrosion resistance and durability. High speed machining (HSM) of CFRP material is needed to study the impact of cutting parameters on cutting forces and chip microstructure which offer vital inputs to the machinability and deformation characteristics of the material. In this work, the orthogonal machining of CFRP was conducted by varying the cutting parameters such as cutting speed and feed rate at high cutting speed/feed rate ranges up to 346 m/min/ 0.446 mm/rev. The impact of the cutting parameters on cutting forces (principal cutting, feed and thrust forces) and chip microstructure were analyzed. A significant impact on thrust forces and chip segmentation pattern was seen at higher feed rates and low cutting speeds.
    Źródło:
    Archives of Metallurgy and Materials; 2017, 62, 3; 1771-1777
    1733-3490
    Pojawia się w:
    Archives of Metallurgy and Materials
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Impact of roguing and insecticide spraying on mosaic disease in Jatropha curcas
    Autorzy:
    Al-Basir, F.
    Roy, P. K.
    Ray, S.
    Powiązania:
    https://bibliotekanauki.pl/articles/205846.pdf
    Data publikacji:
    2017
    Wydawca:
    Polska Akademia Nauk. Instytut Badań Systemowych PAN
    Tematy:
    Jatropha curcas
    mosaic disease
    roguing
    spraying
    Hopf bifurcation
    optimal control problem (OCP)
    Opis:
    Jatropha curcas plant is greatly impaired by mosaic disease, caused by the viruses (Begomovirus), transmitted by whiteflies, which act as the vector. Roguing (i.e. removal of infected plant) and spraying of insecticides are common methods, employed in order to get rid of the disease. In this article, a mathematical model has been developed to study the mosaic disease dynamics while considering preventive measures of roguing and insecticide spraying. Sufficient conditions for the stability of equilibrium points of the system are among the results obtained through qualitative analysis. We obtain the basic reproduction number R0 and show that the disease free system is stable for R0 < 1 and unstable for R0 > 1. The region of stability of equilibrium points in different parameter spaces have also been analysed. Hopf bifurcation at the endemic steady state has been studied subsequently, as well. Finally, by formulating an optimal control problem, optimal application of roguing and spraying techniques has been determined, keeping in mind the cost effective control of the mosaic disease. Pontryagin minimum principle has been utilized to solve the optimal control problem. Numerical simulations illustrate the validity of the analytical outcomes.
    Źródło:
    Control and Cybernetics; 2017, 46, 4; 325-344
    0324-8569
    Pojawia się w:
    Control and Cybernetics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Reactive solute transport in blood flow through a permeable capillary
    Autorzy:
    Debnath, S.
    Roy, A. K.
    Bég, O. A.
    Powiązania:
    https://bibliotekanauki.pl/articles/38695392.pdf
    Data publikacji:
    2022
    Wydawca:
    Instytut Podstawowych Problemów Techniki PAN
    Tematy:
    capillary
    axial flow
    radial flow
    solute dispersion
    Gill decomposition
    filtration coefficient
    exchange coefficient
    advection coefficient
    Opis:
    The present analysis discusses the solute transport process in a steady 2D (axial and radial) laminar flow of blood through a permeable, finite length capillary. Blood is treated as a homogeneous Newtonian fluid and the solute is absorbed at the capillary wall with a linear irreversible reaction rate. The velocity profile is obtained by a regular perturbation technique, whereas the transport coefficients depicted by the Gill generalized dispersion model are solved numerically. A number of different scenarios are considered, namely transport with no-reaction, weak absorption, strong absorption, low filtration or high filtration, etc. In the initial stages, the temporal behaviour of the dispersion coefficient is identical to those cases when there is no radial velocity. For the combined effect of radial and axial velocities, however, the dispersion coefficient is lower for a high absorption rate than for a weak absorption rate. Diffusion is accelerated with higher values of filtration coefficient. Owing to the opposite effects of radial diffusion and radial velocity, the solute particles require more time to reach the steady state. The analysis finds applications in, for example, reactive nutrient and pharmacological transport in capillary hemodynamics.
    Źródło:
    Archives of Mechanics; 2022, 74, 2-3; 173-200
    0373-2029
    Pojawia się w:
    Archives of Mechanics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Optimal selection of dental implant for different bone conditions based on the mechanical response
    Autorzy:
    Roy, S.
    Das, M.
    Chakraborty, P.
    Biswas, J. K.
    Chatterjee, S.
    Khutia, N.
    Saha, S.
    Roychowdhury, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/307549.pdf
    Data publikacji:
    2017
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    wytrzymałość kości
    implanty stomatologiczne
    analiza FEM
    pacjent
    bone condition
    porous dental implant
    FE Analysis
    patient specific
    Opis:
    Bone quality varies from one patient to another extensively; also, Young’s modulus may deviate up to 40% of normal bone quality, which results into alteration of bone stiffness immensely. The prime goal of this study is to design the optimum dental implant considering the mechanical response at bone implant interfaces for a patient with specific bone quality. Method. 3D model of mandible and natural molar tooth were prepared from CT scan data while, dental implants were modelled using different diameter, length and porosity and FE analysis was carried out. Based on the variation in bone density, five different bone qualities were considered. First, failure analysis of implants, under maximum biting force of 250N had been performed; next, the implants, those survived were selected for observing the mechanical response at bone implant interfaces under common chewing load of 120N. Result. Maximum Von Mises stress did not surpass the yield strength of the implant material (TiAl4V). However, factor of safety of 1.5 was considered and all but two dental implants survived the design stress or allowable stress. Under 120N load, distribution of Von Mises stress and strain at the bone-implant interface corresponding to the rest of the implants for five bone conditions were obtained and enlisted. Conclusion. Implants, exhibiting interface strain within 1500-3000 microstrain range show the best bone remodelling and osseointegration. So, implant models, having this range of interface strains were selected corresponding to the particular bone quality. A set of optimum dental implants for each of the bone qualities were predicted.
    Źródło:
    Acta of Bioengineering and Biomechanics; 2017, 19, 2; 11-20
    1509-409X
    2450-6303
    Pojawia się w:
    Acta of Bioengineering and Biomechanics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-12 z 12

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