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Wyszukujesz frazę "Roy, A." wg kryterium: Autor


Tytuł:
Electron-ion Recombination at Sub-zero Temperature
Autorzy:
Bhattacharyya, S.
Roy, A.
Powiązania:
https://bibliotekanauki.pl/articles/2008325.pdf
Data publikacji:
1999-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
32.70.Fw
34.80.Kw
Opis:
In this paper we have considered two-step radiative recombination channel over the existing spontaneous radiative recombination channel to explain the causes of experimentally obtained enhanced recombination rate at sub-zero temperature. The existing recombination rate due to spontaneous radiative recombination is 4 times smaller than the recent experimental data. In the case of Ne$\text{}^{10+}$ we obtain good agreement between theory and experiment when contribution from two-step radiative recombination channel is added to the spontaneous radiative recombination channel. Recombination rate for Ar$\text{}^{18+}$ is calculated. The radiation spectrum given out by two-step radiative recombination and spontaneous radiative recombination in the recombination rate processes are discrete spectrum and continuous spectrum, respectively. Experimental identification of these two channels through the spectral signatures is suggested.
Źródło:
Acta Physica Polonica A; 1999, 95, 6; 911-920
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Three-Particle Recombination at Low Temperature: a QED Approach
Autorzy:
Bhattacharyya, S.
Roy, A.
Powiązania:
https://bibliotekanauki.pl/articles/2027431.pdf
Data publikacji:
2001-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
32.80.Fb
33.55.Ad
Opis:
A theoretical study of the three-body recombination of proton and electron in presence of a spectator electron with electronic beam at near-zero temperature is presented using field theory and invariant Lorentz gauge. Contributions from the Feynman diagrams of different orders give an insight into the physics of the phenomena. Recombination rate coefficient is obtained for low lying principal quantum number n=1 to 10. At a fixed ion beam temperature (300 K) recombination rate coefficient is found to increase in general with n, having a flat and a sharp peak at quantum states 3 and 5, respectively. In absence of any other theoretical and experimental results for low temperature formation of H-atom by three-body recombination at low lying quantum states, we have presented the theoretical results of Stevefelt and group for three-body recombination of deuteron with electron along with the present results. Three-body recombination of antihydrogen in antiproton-positron plasma is expected to yield similar result as that for three-body recombination of hydrogen formation in proton-electron plasma. The necessity for experimental investigation of low temperature three-body recombination at low quantum states is stressed.
Źródło:
Acta Physica Polonica A; 2001, 100, 1; 23-40
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
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:
Ejaculation malfunctions on the day of oocyte pick up for IVF/ICSI: A report of four cases
Autorzy:
Javed, A.
Ls, A.
Pathangae, V.G.
Roy, A.
Ganguly, D.
Powiązania:
https://bibliotekanauki.pl/articles/10946.pdf
Data publikacji:
2015
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Opis:
The procedure of in-vitro fertilization (IVF) is sometime physically stressful and emotional turmoil on the couples undergoing treatment. The male partner is obliged to produce semen for injection/insemination with the oocytes. Unfortunately, some men are ill-fated, not capable to reproduce semen on the day of oocyte pickup.
Źródło:
International Letters of Natural Sciences; 2015, 48
2300-9675
Pojawia się w:
International Letters of Natural Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
T-cell proliferation on immunopathogenic mechanism of psoriasis: a control based theoretical approach
Autorzy:
Datta, A.
Roy, P. K.
Powiązania:
https://bibliotekanauki.pl/articles/205612.pdf
Data publikacji:
2013
Wydawca:
Polska Akademia Nauk. Instytut Badań Systemowych PAN
Tematy:
T-cells
dendritic cells
keratinocytes
dermis
epidermis
cytokines
T-cell proliferation
drug efficacy
optimal control
Opis:
Psoriasis vulgaris is a common, worldwide autoimmune skin disorder characterized by T-cells mediated hyperproliferation of keratinocytes. The feature of T-cells arbitrated psoriatic lesions is the epidermal infiltration of oligoclonal CD8+ T-cells and also of CD4+ T-cells in the dermis. Psoriatic scratches are identified by red and enlarged lesions along with silver whitish scales. In this article, we propose a mathematical model for psoriasis, involving a set of differential equations, concerning T-cells, dendritic cells and epidermal keratinocytes. We introduce T-cell proliferation in the system, where T-cells are generated through expansion of accessible CD4+ T-cells from precursors. We are interested in observing how the cell biological system develops through T-cell proliferation in presence of control with respect to T-cells and keratinocytes. We study the model in both implicit and explicit ways and measure the effect of drug on the system through impulsive drug therapy.
Źródło:
Control and Cybernetics; 2013, 42, 2; 365-386
0324-8569
Pojawia się w:
Control and Cybernetics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Design and Analysis of Single Mode Photonic Crystal Fibers with Zero Dispersion and Ultra Low Loss
Autorzy:
Kumar, P.
Tripathy, A.
Roy, J. S.
Powiązania:
https://bibliotekanauki.pl/articles/963925.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
photonic crystal fibers
dispersion
birefringence
splice loss
confinement loss
effective mode area
Opis:
PCFs (Photonic Crystal Fibers) with ‘T’ – shaped core have been proposed in this paper. ‘T’ –shaped core PCF structures have been analyzed using two different background materials: silica and lead silicate. A total of 360° rotation at an interval of 90° has been introduced in the design of PCF structures. PCF structures A, B, C and D with rotation of 0°, 90°, 180° and 270° have silica as wafer. Similarly PCF structures E, F, G and H with similar rotation have lead silicate as background material. Numerical investigations shows structures ‘D’, ‘F’, ‘G’ and ‘H’ to have anomalous dispersion. PCF structures ‘F’, ‘G’, and ‘H’ have reported birefringence of the order of 10⁻². Besides, other PCF structures report birefringence of the order of 10⁻³. Ultra low confinement loss has been observed in all the investigated PCF structures. Moreover, splice loss observed by the structure is very low. Large mode area has been shown by all the designed PCF structures.
Źródło:
International Journal of Electronics and Telecommunications; 2018, 64, 4; 541-546
2300-1933
Pojawia się w:
International Journal of Electronics and Telecommunications
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Unsteady laminar mixed convection boundary layer flow near a vertical wedge due to oscillations in the free-stream and surface temperature
Autorzy:
Roy, N. C.
Hossain, A.
Hussain, S.
Powiązania:
https://bibliotekanauki.pl/articles/264762.pdf
Data publikacji:
2016
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
konwekcja mieszana
granica przepływu warstwy
przepływ ciepła
mixed convection
boundary layer flow
vertical wedge
free-stream oscillation
Opis:
The unsteady laminar boundary layer characteristics of mixed convection flow past a vertical wedge have been investigated numerically. The free-stream velocity and surface temperature are assumed to be oscillating in the magnitude but not in the direction of the oncoming flow velocity. The governing equations have been solved by two distinct methods, namely, the straightforward finite difference method for the entire frequency range, and the extended series solution for low frequency range and the asymptotic series expansion method for high frequency range. The results demonstrate the effects of the Richardson number, Ri, introduced to quantify the influence of mixed convection and the Prandtl number, Pr, on the amplitudes and phase angles of the skin friction and heat transfer. In addition, the effects of these parameters are examined in terms of the transient skin friction and heat transfer.
Źródło:
International Journal of Applied Mechanics and Engineering; 2016, 21, 1; 169-186
1734-4492
2353-9003
Pojawia się w:
International Journal of Applied Mechanics and Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Negative Shrinkage of Thin-walled Investment Brass Castings
Autorzy:
Roy, Soumyajit
Pramanick, A. K.
Datta, P. K.
Powiązania:
https://bibliotekanauki.pl/articles/27314113.pdf
Data publikacji:
2023
Wydawca:
Polska Akademia Nauk. Czasopisma i Monografie PAN
Tematy:
"Dokra or Dhokra"
cast craft tradition
India
thin-walled castings
brass castings
tradycyjna metoda odlewnicza
Indie
odlewy cienkościenne
odlewy mosiężne
forma odlewnicza
Opis:
Dhokra or Dokra casting is a sophisticated cast metal craft tradition of the Indian subcontinent. It has been practiced by the countryfolk now since the Copper Age. It is a lost wax casting process in the hot clay mold. The technology is such sophisticated that it can produce up to 400 μm thin-walled hollow cast products with complicated and intricate shapes using Brass, Bronze, Copper, and other copper alloys. The investigation was for engraving Brass (2% lead) which is used by Dhokra artisans nowadays. In a field visit during dimensional analysis, one discrepancy was identified. The metal thicknesses of hollow castings are thicker than the thickness of the wax pattern. This cast metal dilation phenomenon is unusual. Shrinkage of metals compared to the pattern dimension is familiar in the casting world. The same abnormalities in the repeated investigation at different sites were observed. All the studies and experiments were organized to explain the reason hidden behind the phenomenon.
Źródło:
Archives of Foundry Engineering; 2023, 23, 1; 17--24
1897-3310
2299-2944
Pojawia się w:
Archives of Foundry Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł

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