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Wyszukujesz frazę "Modulation" wg kryterium: Temat

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    Wyświetlanie 1-8 z 8
    Tytuł:
    Chaotic convection of viscoelastic fluid in porous medium under G-jitter
    Autorzy:
    Bhadauria, B. S.
    Singh, A.
    Singh, M. K.
    Powiązania:
    https://bibliotekanauki.pl/articles/265559.pdf
    Data publikacji:
    2019
    Wydawca:
    Uniwersytet Zielonogórski. Oficyna Wydawnicza
    Tematy:
    teoria nieliniowa
    grawitacja
    konwekcja
    non-linear theory
    gravity modulation
    chaotic convection
    Opis:
    The present article aims at investigating the effect of gravity modulation on chaotic convection of a viscoelastic fluid in porous media. For this, the problem is reduced into Lorenz system (non-autonomous) by employing the truncated Galerkin expansion method. The system shows transitions from periodic to chaotic behavior on increasing the scaled Rayleigh number R. The amplitude of modulation advances the chaotic nature in the system while the frequency of modulation has a tendency to delay the chaotic behavior which is in good agreement with the results due to [1]. The behavior of the scaled relaxation and retardation parameter on the system is also studied. The phase portrait and time domain diagrams of the Lorenz system for suitable parameter values have been used to analyze the system.
    Źródło:
    International Journal of Applied Mechanics and Engineering; 2019, 24, 1; 37-51
    1734-4492
    2353-9003
    Pojawia się w:
    International Journal of Applied Mechanics and Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    The effect of modulation on heat transport by a weakly nonlinear thermal instability in the presence of applied magnetic field and internal heating
    Autorzy:
    Manjula, S. H.
    Kiran, Palle
    Narsimlu, G.
    Roslan, R.
    Powiązania:
    https://bibliotekanauki.pl/articles/1839705.pdf
    Data publikacji:
    2020
    Wydawca:
    Uniwersytet Zielonogórski. Oficyna Wydawnicza
    Tematy:
    modulacja
    pole magnetyczne
    ogrzewanie
    Ginzburg-Landau equation
    temperature modulation
    applied magnetic field
    internal heating
    Opis:
    The present paper deals with a weakly nonlinear stability problem under an imposed time-periodic thermal modulation. The temperature has two parts: a constant part and an externally imposed time-dependent part. We focus on stationary convection using the slow time scale and quantify convective amplitude through the real Ginzburg-Landau equation (GLE). We have used the classical fourth order Runge-Kutta method to solve the real Ginzburg-Landau equation. The effect of various parameters on heat transport is discussed through GLE. It is found that heat transport analysis is controlled by suitably adjusting the frequency and amplitude of modulation. The applied magnetic field (effect of Ha) is to diminish the heat transfer in the system. Three different types of modulations thermal, gravity, and magnetic field have been compared. It is concluded that thermal modulation is more effective than gravity and magnetic modulation. The magnetic modulation stabilizes more and gravity modulation stabilizes partially than thermal modulation.
    Źródło:
    International Journal of Applied Mechanics and Engineering; 2020, 25, 4; 96-115
    1734-4492
    2353-9003
    Pojawia się w:
    International Journal of Applied Mechanics and Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Effect of vertical vibrations on the onset of binary convection
    Autorzy:
    Swamy, M. S.
    Powiązania:
    https://bibliotekanauki.pl/articles/265645.pdf
    Data publikacji:
    2013
    Wydawca:
    Uniwersytet Zielonogórski. Oficyna Wydawnicza
    Tematy:
    grawitacja
    metoda perturbacji
    funkcja Rayleigha
    gravity modulation
    g-jitter
    double diffusive convection
    perturbation method
    Opis:
    In the present work the linear stability analysis of double diffusive convection in a binary fluid layer is performed. The major intention of this study is to investigate the influence of time-periodic vertical vibrations on the onset threshold. A regular perturbation method is used to compute the critical Rayleigh number and wave number. A closed form expression for the shift in the critical Rayleigh number is calculated as a function of frequency of modulation, the solute Rayleigh number, Lewis number, and Prandtl number. These parameters are found to have a significant influence on the onset criterion; therefore the effective control of convection is achieved by proper tuning of these parameters. Vertical vibrations are found to enhance the stability of a binary fluid layer heated and salted from below. The results of this study are useful in the areas of crystal growth in micro-gravity conditions and also in material processing industries where vertical vibrations are involved.
    Źródło:
    International Journal of Applied Mechanics and Engineering; 2013, 18, 3; 899-910
    1734-4492
    2353-9003
    Pojawia się w:
    International Journal of Applied Mechanics and Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    The complex Ginzburg Landau model for an oscillatory convection in a rotating fluid layer
    Autorzy:
    Manjula, S. H.
    Kiran, P.
    Reddy, P. Raj
    Bhadauria, B. S.
    Powiązania:
    https://bibliotekanauki.pl/articles/266148.pdf
    Data publikacji:
    2020
    Wydawca:
    Uniwersytet Zielonogórski. Oficyna Wydawnicza
    Tematy:
    konwekcja
    teoria nieliniowa
    liczba Nusselta
    convection
    finite amplitude
    nonlinear theory
    rotation modulation
    Nusselt number
    Opis:
    A weakly nonlinear thermal instability is investigated under rotation speed modulation. Using the perturbation analysis, a nonlinear physical model is simplified to determine the convective amplitude for oscillatory mode. A non-autonomous complex Ginzburg-Landau equation for the finite amplitude of convection is derived based on a small perturbed parameter. The effect of rotation is found either to stabilize or destabilize the system. The Nusselt number is obtained numerically to present the results of heat transfer. It is found that modulation has a significant effect on heat transport for lower values of ωf while no effect for higher values. It is also found that modulation can be used alternately to control the heat transfer in the system. Further, oscillatory mode enhances heat transfer rather than stationary mode.
    Źródło:
    International Journal of Applied Mechanics and Engineering; 2020, 25, 1; 75-91
    1734-4492
    2353-9003
    Pojawia się w:
    International Journal of Applied Mechanics and Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    M-ary phase modulation for digital watermarking
    Autorzy:
    Xin, Y.
    Pawlak, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/908050.pdf
    Data publikacji:
    2008
    Wydawca:
    Uniwersytet Zielonogórski. Oficyna Wydawnicza
    Tematy:
    cyfrowy znak wodny
    odporność
    pojemność danych
    multibit watermarking
    M-ary phase modulation
    watermark robustness
    data capacity
    Opis:
    In spread spectrum based watermarking schemes, it is a challenging task to embed multiple bits of information into the host signal. M-ary modulation has been proposed as an effective approach to multibit watermarking. It has been proved that an M-ary modulation based watermarking system outperforms significantly a binary modulation based watermarking system. However, in the existing M-ary modulation based algorithms, the value of M is restricted to be less than 256, because as M increases, the computation workload for data extraction advances exponentially. In this paper, we propose an efficient M-ary modulation scheme, i.e., M-ary phase modulation, which reduces the computation in data extraction to a very low level. With this scheme, it is practical to implement an M-ary modulation based algorithm with a high value of M, e.g., M = 220. This is significant for a watermarking system, because it can either greatly increase the data capacity of a watermark given the necessary watermark robustness, or considerably improve the watermark robustness given the amount of information of the watermark. The superiority of the proposed scheme is verified by simulation results.
    Źródło:
    International Journal of Applied Mathematics and Computer Science; 2008, 18, 1; 93-104
    1641-876X
    2083-8492
    Pojawia się w:
    International Journal of Applied Mathematics and Computer Science
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Stability analysis and internal heating effect on oscillatory convection in a viscoelastic fluid saturated porous medium under gravity modulation
    Autorzy:
    Bhadauria, B. S.
    Singh, M. K.
    Singh, A.
    Singh, B. K.
    Kiran, P.
    Powiązania:
    https://bibliotekanauki.pl/articles/265014.pdf
    Data publikacji:
    2016
    Wydawca:
    Uniwersytet Zielonogórski. Oficyna Wydawnicza
    Tematy:
    analiza stabilności
    grawitacja
    ciecz lepkosprężysta
    nonlinear stability analysis
    complex Ginzburg-Landau equation
    gravity modulation
    internal heating
    bifurcation
    Opis:
    In this paper, we investigate the combined effect of internal heating and time periodic gravity modulation in a viscoelastic fluid saturated porous medium by reducing the problem into a complex non-autonomous Ginzgburg-Landau equation. Weak nonlinear stability analysis has been performed by using power series expansion in terms of the amplitude of gravity modulation, which is assumed to be small. The Nusselt number is obtained in terms of the amplitude for oscillatory mode of convection. The influence of viscoelastic parameters on heat transfer has been discussed. Gravity modulation is found to have a destabilizing effect at low frequencies and a stabilizing effect at high frequencies. Finally, it is found that overstability advances the onset of convection, more with internal heating. The conditions for which the complex Ginzgburg-Landau equation undergoes Hopf bifurcation and the amplitude equation undergoes supercritical pitchfork bifurcation are studied.
    Źródło:
    International Journal of Applied Mechanics and Engineering; 2016, 21, 4; 785-803
    1734-4492
    2353-9003
    Pojawia się w:
    International Journal of Applied Mechanics and Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    The effect of thermal modulation on double diffusive convection in the presence of applied magnetic field and internal heat source
    Autorzy:
    Manjula, S. H.
    Suresh, P.
    Rao, M. G.
    Powiązania:
    https://bibliotekanauki.pl/articles/1839901.pdf
    Data publikacji:
    2021
    Wydawca:
    Uniwersytet Zielonogórski. Oficyna Wydawnicza
    Tematy:
    analiza nieliniowa
    płyn newtonowski
    konwekcja
    thermal modulation
    weak nonlinear analysis
    internal heating
    newtonian fluid
    double diffusive convection
    Opis:
    The investigation of thermal modulation on double-diffusive stationary convection in the presence of an applied magnetic field and internal heating is carried out. A weakly nonlinear stability analysis has been performed using the finite-amplitude Ginzburg-Landau model. This finite amplitude of convection is obtained at the third order of the system. The study considers three different forms of temperature modulations. OPM-out of phase modulation, LBMO-lower boundary modulation, IPM-in phase modulation. The finite-amplitude is a function of amplitude ,Tδ frequency ω and the phase differenceθ . The effects of Tδ and ω on heat/mass transports have been analyzed and depicted graphically. The study shows that heat/mass transports can be controlled effectively by thermal modulation. Further, it is found that the internal Rayleigh number iR enhances heat transfer and reduces the mass transfer in the system.
    Źródło:
    International Journal of Applied Mechanics and Engineering; 2021, 26, 1; 135-155
    1734-4492
    2353-9003
    Pojawia się w:
    International Journal of Applied Mechanics and Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Weakly nonlinear oscillatory convection in a viscoelastic fluid saturated porous medium with throughflow and temperature modulation
    Autorzy:
    Kiran, P.
    Narasimhulu, Y.
    Manjula, S. H.
    Powiązania:
    https://bibliotekanauki.pl/articles/265198.pdf
    Data publikacji:
    2018
    Wydawca:
    Uniwersytet Zielonogórski. Oficyna Wydawnicza
    Tematy:
    przepływ
    modulacja temperatury
    teoria nieliniowa
    model Ginzburga-Landaua
    throughflow
    temperature modulation
    weak nonlinear theory
    complex Ginzburg-Landau model
    Opis:
    The effect of vertical throughfow and temperature modulation on a viscoelastic fluid saturated porous medium has been investigated. The amplitudes of temperature modulation at the lower and upper surfaces are considered to be very small and the disturbances are expanded in terms of power series of amplitude of convection. A weak nonlinear stability analysis has been performed for the oscillatory mode of convection, and heat transport in terms of the Nusselt number, which is governed by the non autonomous complex Ginzburg- Landau equation, is calculated. The effect of vertical through flow is found to stabilize the system irrespective of the direction of through flow in the case of permeable boundary conditions. The time relaxation has a destabilizing effect, while the time retardation parameter has a stabilizing effect on the system. The effects of amplitude and frequency of modulation on heat transport have been analyzed and depicted graphically. The study shows that the heat transport can be controlled effectively by a mechanism that is external to the system. Further, it is also found that heat transfer is more in oscillatory mode of convection rather than in stationary mode of convection.
    Źródło:
    International Journal of Applied Mechanics and Engineering; 2018, 23, 3; 635-653
    1734-4492
    2353-9003
    Pojawia się w:
    International Journal of Applied Mechanics and Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-8 z 8

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