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1.
Numerical investigation of the dusty Williamson fluid with the dependency of time has been done in current disquisition. The flow of multiphase liquid/particle suspension saturating the medium is caused by stretching of porous surface. The influence of magnetic field and heat generation/absorption is observed. It is assumed that particle has a spherical shape and distributed uniformly in fluid matrix. The unsteady two-dimensional problems are modeled for both fluid and particle phase using conservation of mass, momentum and heat transfer. The finalized model generates the non-dimensioned parameters, namely Weissenberg number, unsteadiness parameter, magnetic parameter,heat generation/absorption parameter, Prandtl number, fluid particle interaction parameter, and mass concentration parameters. The numerical solution is obtained. Locality of skin friction and Nusselt number is deliberately focused to help of tables and graphs. While inferencing the current article it is clearly observed that increment of Williamson parameter, unsteadiness parameter, magnetic parameter, volume fraction parameter, and mass concentration parameter reduces the velocity profile of fluid and solid particles as well. And increment of Prandtl number, unsteadiness parameter,volume fraction parameter, and mass concentration parameter reduces the temperature profile of fluid and solid particles as well. 相似文献
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Yoshiharu Sato Kazuaki Sugawa Michiaki Kawaguchi 《Reports on Mathematical Physics》1979,16(1):111-119
The differential geometrical consideration of the parameter space, especially as a Riemannian geometry, was initiated by C.R. Rao in 1945. This approach appears to be important for the problem of estimation and test of hypotheses as well as for applications to physical problems. It has been shown that the parameter spaces of univariate normal distribution, univariate exponential distribution and multinomial distribution are Riemannian spaces of constant curvature. In the present paper the discussion is confined to the parameter space of the two-dimensional normal distribution. It has been shown that in general the parameter space is not necessarily of a constant curvature and that, if the correlation coefficient vanishes, the parameter space becomes an Einstein space. In addition, some invariant quantities, as sectional curvature, mean curvature and scalar curvature, have been calculated. 相似文献
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In this Letter we present a noncommutative version of scalar field cosmology. We find the noncommutative Friedmann equations as well as the noncommutative Klein–Gordon equation, interestingly the noncommutative contributions are only present up to second order in the noncommutative parameter. Finally we conclude that if we want a noncommutative minisuperspace with a constant noncommutative parameter as viable phenomenological model, the noncommutative parameter has to be very small. 相似文献
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运用密度矩阵方法推导出了特殊非对称量子阱中电光系数的解析表达式,并以典型的GaAs/AlGaAs非对称量子阱为例进行了数字计算.计算结果表明,量子阱的非对称性随着参数a的增大而增强,随着参数V0的增大而减小.电光系数的最大值也随着参数a的增大而增大,随着参数V0的增大而减小,表明电光系数将随着量子阱非对称性的增大而增大.在取不同的参数a和不同的参数V0时,电光系数和入射光子能量的关系分别被绘制成曲线图.在图中分别有三个不同的峰,而且系统的非对称性越大,峰值就越大.随着量子阱非对称性的增大,曲线中的峰向能量低的方向移动.另外,在这种量子阱中得到了比较大的电光系数,大约在10-6m/V量级.随着近来纳米制作技术的进步,使得在实验上制作这种特殊非对称量子阱并得到较好的非线性材料成为可能. 相似文献
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Zhou C Lai CH 《Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics》1999,59(6):6629-6636
It has been proposed to realize secure communication using chaotic synchronization via transmission of a binary message encoded by parameter modulation in the chaotic system. This paper considers the use of parameter adaptive control techniques to extract the message, based on the assumptions that we know the equation form of the chaotic system in the transmitter but do not have access to the precise values of the parameters which are kept secret as a secure set. In the case in which a synchronizing system can be constructed using parameter adaptive control by the transmitted signal and the synchronization is robust to parameter mismatches, the parameter modulation can be revealed and the message decoded without resorting to exact parameter values in the secure set. A practical local Lyapunov function method for designing parameter adaptive control rules based on originally synchronized systems is presented. 相似文献
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Data assimilation-based parameter estimation can be used to deterministically tune forecast models. This work demonstrates that it can also be used to provide parameter distributions for use by stochastic parameterization schemes. While parameter estimation is (theoretically) straightforward to perform, it is not clear how one should physically interpret the parameter values obtained. Structural model inadequacy implies that one should not search for a deterministic “best” set of parameter values, but rather allow the parameter values to change as a function of state; different parameter values will be needed to compensate for the state-dependent variations of realistic model inadequacy. Over time, a distribution of parameter values will be generated and this distribution can be sampled during forecasts. The current work addresses the ability of ensemble-based parameter estimation techniques utilizing a deterministic model to estimate the moments of stochastic parameters. It is shown that when the system of interest is stochastic the expected variability of a stochastic parameter is biased when a deterministic model is employed for parameter estimation. However, this bias is ameliorated through application of the Central Limit Theorem, and good estimates of both the first and second moments of the stochastic parameter can be obtained. It is also shown that the biased variability information can be utilized to construct a hybrid stochastic/deterministic integration scheme that is able to accurately approximate the evolution of the true stochastic system. 相似文献
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We present a novel solution algorithm for 3D parameter identification based on low frequency electromagnetic data. With focus on large-scale applications such as monitoring of subsea oil production, CO2 sequestration, and geothermal systems, the proposed solution algorithm is designed to meet challenges related to low parameter sensitivity, nonuniqueness of the inverse solutions, nonlinearity in the mapping from the data to the parameter space, and costly numerical simulations. Motivated by earlier investigations on the relation between sensitivity, nonlinearity and scale, the proposed solution approach is based on a reduced, composite parameter representation. Though a reduced representation restricts the solution space, flexibility with respect to which parameter functions that can be represented is obtained by facilitating the estimation of the structure and smoothness of the representation itself. Moreover, the resolution of the parameter function is detached from the computational grid and determined as part of the estimation. The performance of the proposed solution algorithm is illustrated through numerical examples for identification of underground electric conductivity changes from time-lapse electromagnetic observations. 相似文献
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t' Hooft's disorder parameter is written as a Euclidean functional integral over fields with singular boundary conditions. Meron-like configurations are constructed and their contributions to the disorder parameter is evaluated approximately. The calculated disorder parameter exhibits a confinement phase behaviour. 相似文献
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《Physics letters. A》2019,383(17):2011-2020
The detuning parameter in experimentally feasible off-resonant Raman process is shown as a control parameter to probe and enhance the nonclassicality generated in the output of the process. Specifically, the normal characteristic function is obtained for the process as a function of detuning parameters in Stokes and anti-Stokes generation processes using more general solution than the conventional short-time solution under complete quantum treatment, which remains in the multimode Gaussian form. Single- and two-mode squeezing and antibunching as well as intermodal entanglement are reported in terms of experimentally accessible quantum noise fluctuations considering either phonon mode coherent or chaotic. Further, the joint photon-phonon number and integrated intensity distributions reveal a higher number of Stokes-phonon (pump-phonon) pair generation for the lower (higher) values of detuning parameter in Stokes generation. Pump-phonon pair generation is also supported by the lower values of detuning parameter in anti-Stokes generation. 相似文献
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Exact solutions for the flow of Casson fluid over a stretching surface with transpiration and heat transfer effects
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The effects of transpiration on forced convection boundary layer non-Newtonian fluid flow and heat transfer toward a linearly stretching surface are reported.The flow is caused solely by the stretching of the sheet in its own plane with a velocity varying linearly with the distance from a fixed point.The constitutive relationship for the Casson fluid is used.The governing partial differential equations corresponding to the momentum and energy equations are converted into non-linear ordinary differential equations by using similarity transformations.Exact solutions of the resulting ordinary differential equations are obtained.The effect of increasing Casson parameter,i.e.,with decreasing yield stress(the fluid behaves as a Newtonian fluid as the Casson parameter becomes large),is to suppress the velocity field.However,the temperature is enhanced as the Casson parameter increases.It is observed that the effect of transpiration is to decrease the fluid velocity as well as the temperature.The skin-friction coefficient is found to increase as the transpiration parameter increases. 相似文献
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Chaos in the dc and rf current driven Josephson junction is investigated by measurements on a phase-locked loop. The method allows a direct display of the Poincaré map and the bifurcation diagram, as the parameter space is searched. In some regions of the parameter space the Feigenbaum period-doubling route to chaos is observed upon a change of any parameter. 相似文献
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Stochastic period-doubling bifurcation in biharmonic driven Dulling system with random parameter
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Stochastic period-doubling bifurcation is explored in a forced Duffing system with a bounded random parameter as an additional weak harmonic perturbation added to the system. Firstly, the biharmonic driven Duffing system with a random parameter is reduced to its equivalent deterministic one, and then the responses of the stochastic system can be obtained by available effective numerical methods. Finally, numerical simulations show that the phase of the additional weak harmonic perturbation has great influence on the stochastic period-doubling bifurcation in the biharmonic driven Duffing system. It is emphasized that, different from the deterministic biharmonic driven Duffing system, the intensity of random parameter in the Duffing system can also be taken as a bifurcation parameter, which can lead to the stochastic period-doubling bifurcations. 相似文献
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The widely used traditional massless isolator model is only valid at relatively low frequencies. In this paper two classes of distributed parameter isolator, non-dispersive and dispersive, which are valid over a wide range of frequencies, are studied and compared. The important characteristics of such distributed parameter isolators in isolating a mass are given, as are the parameters which control the isolator performance at various frequencies. The theoretical findings for one distributed parameter isolator are validated experimentally using a helical spring, as an example of a non-dispersive isolator. 相似文献
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The collective behaviors of populations of coupled oscillators have attracted significant attention in recent years. In this paper, an order parameter approach is proposed to study the low-dimensional dynamical mechanism of collective synchronizations, by adopting the star-topology of coupled oscillators as a prototype system. The order parameter equation of star-linked phase oscillators can be obtained in terms of the Watanabe–Strogatz transformation, Ott–Antonsen ansatz, and the ensemble order parameter approach. Different solutions of the order parameter equation correspond to the diverse collective states, and different bifurcations reveal various transitions among these collective states. The properties of various transitions in the star-network model are revealed by using tools of nonlinear dynamics such as time reversibility analysis and linear stability analysis. 相似文献
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R. Lafaye T. Plehn M. Rauch D. Zerwas 《The European Physical Journal C - Particles and Fields》2008,54(4):617-644
If new physics is found at the LHC (and the ILC) the reconstruction of the underlying theory should not be biased by assumptions
about high-scale models. For the mapping of many measurements onto high-dimensional parameter spaces we introduce SFitter
with its new weighted Markov chain technique. SFitter constructs an exclusive likelihood map, determines the best-fitting
parameter point and produces a ranked list of the most likely parameter points. Using the example of the TeV-scale supersymmetric
Lagrangian we show how a high-dimensional likelihood map will generally include degeneracies and strong correlations. SFitter
allows us to study such model-parameter spaces employing Bayesian as well as frequentist constructions. We illustrate in detail
how it should be possible to analyze high-dimensional new-physics parameter spaces like the TeV-scale MSSM at the LHC. A combination
of LHC and ILC measurements might well be able to completely cover highly complex TeV-scale parameter spaces. 相似文献