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1.
S. K. El-Labany E. F. El-Shamy S. K. El-Sherbeny 《Astrophysics and Space Science》2014,351(1):151-158
The oblique collision of nonlinear quantum dust-acoustic (NQDA) solitary waves in a three-dimensional (3D) magnetized dense dusty plasma is investigated. Furthermore, two coupled Kortwege–de Vries equations for describing our model and the analytical phase shifts after the oblique collision of two NQDA solitary waves are derived using the extended Poincaré–Lighthill–Kuo (PLK) method. The modification in the phase shift and the trajectory of the NQDA solitary waves structures due to the inclusion of oblique collision and external magnetic field are discussed numerically. The numerical results are applied to high density astrophysical situations such as in superdense white dwarfs. 相似文献
2.
A ROBUST PLS PROCEDURE 总被引:1,自引:0,他引:1
A robust partial least squares(PLS)regression algorithm is developed.This is achieved by substitutionof the univariate regression steps in the iterative PLS2 algorithm by a robust alternative.The anglebetween loading vectors from both perturbed and unperturbed solutions is used as a measure ofrobustness.By means of a perturbation study on a structure-activity data set,it is demonstrated thatthe stability of the robust method is superior to standard PLS. 相似文献
3.
M. Shalaby S. K. El-Labany E. F. El-Shamy M. A. Khaled 《Astrophysics and Space Science》2010,326(2):273-279
The propagation of solitary waves in an unmagnetized collisional dusty plasma consisting of a negatively charged dust fluid,
positively charged ions, isothermal electrons, and background neutral particles is studied. The ionization, ion loss, ion–neutral,
ion–dust, and dust–neutral collisions are considered. Applying a reductive perturbation theory, a damped Korteweg–de Vries
(DKdV) equation is derived. On the other hand, at a critical phase velocity, the dynamics of solitary waves is governed by
a damped modified Korteweg–de Vries (DMKdV) equation. The nonlinear properties of solitary waves in the two cases are discussed. 相似文献
4.
E. F. El-Shamy W. F. El-Taibany E. K. El-Shewy K. H. El-Shorbagy 《Astrophysics and Space Science》2012,338(2):279-285
The characteristics of the head-on collision (HOC) between two positron acoustic solitary waves (PASWs) in a four component
electron-positron-ion (EPI) space plasma have been investigated theoretically, using the extended Poincaré-Lighthill-Kuo (PLK)
method. The analytical phase shifts after the collision of the two solitary waves occurs are derived. Numerically, the influences
of the cold/hot positron parameters on the phase shifts are explicitly investigated. The present theory is applied to analyze
the formation and the interaction of localized coherent PASWs structures in space plasmas (pulsar environments). 相似文献
5.
The propagation and the head—on collision of nonlinear dust—acoustic solitary waves (DASWs) in dusty plasmas consisting of
electrons, ions and negative as well as positive dust particles are investigated. Applying an extended Poincaré-Lighthill-Kuo
(PLK) method, Kortwege-de Vries equations and analytical phase shifts after the head-on collision of two DASWs in dusty plasmas
are obtained. Analytically and numerically, the relevance of the phase shifts and trajectories to the positive-to-negative
dust number density ratio, the ratio of the ion number density to negative dust number density, negative-to-positive dust
particle mass ratio, and the ion-to-electron temperature ratio effects is explicitly demonstrated. Moreover, the current findings
are applied to different regions of space, viz. cometary tails, mesosphere, Jupiter’s magnetosphere. 相似文献
6.
S. K. El-Labany E. F. El-Shamy S. A. El-Warraki 《Astrophysics and Space Science》2008,315(1-4):287-295
Nonlinear properties of the dust acoustic (DA) solitary waves in a dusty plasma consisting of negatively variable-charged dust particles, vortex-like distributed ions and two-temperature isothermal electrons are reported. A reductive perturbation theory has been used to derive a modified Korteweg-de Vries (mKdV) equation for the first-order perturbed potential and a linear inhomogeneous mKdV-type equation for the second-order perturbed potential. The renormalization method is used to obtain stationary solutions of these coupled equations. The modifications in the amplitude and width of the solitary wave structure due to the inclusion of two different types of isothermal electrons, external oblique magnetic field, higher-order nonlinearity, and vortex-like distributed ions are investigated. Also a method based on energy consideration was used to obtain the stability condition. Moreover, the numerical results are applied to investigate some nonlinear characteristics of the DA solitary waves. 相似文献
7.
The nonlinear properties of solitary waves structure in a hot magnetized dusty plasma consisting of a negatively charged,
extremely massive hot dust fluid, positively charged hot ion fluid and vortex-like distributed electrons, are reported. A
modified Korteweg de Vries equation (mKdV) which admits a solitary wave solution for small but finite amplitude is derived
using a reductive perturbation theory. The modifications in the amplitude and width of the solitary wave structures due to
the inclusion of an external magnetic field and dust and ions temperature are investigated.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
8.
The head-on collision between two quantum dust-acoustic solitary waves (QDASWs) in ultradense astrophysical objects has been investigated theoretically using the extended Poincaré-Lighthill-Kuo (PLK) method. The Korteweg-de Vries equations and the analytical phase shifts after the head-on collision of the two QDASWs in quantum dusty plasmas are obtained. Numerically, the obtained results demonstrate that the dust size distribution, the quantum corrections of diffraction and the temperatures of electrons and ions have strong effects on the nature of the phase shifts and the trajectories of the two QDASWs after collision. 相似文献
9.
S. K. El-Labany E. F. El-Shamy R. Sabry M. Shokry 《Astrophysics and Space Science》2010,325(2):201-207
In the present paper, the characteristics of the head-on collision between two dust-acoustic solitary waves (DASWs) in an
adiabatic dusty plasma consisting of variable negatively charged dust grains, isothermal electrons and two-temperature isothermal
ions in the presence of an external oblique magnetic field are investigated. Using the extended Poincaré–Lighthill–Kuo (PLK)
method, the Korteweg–de Vries (KdV) equations and the analytical phase shifts after the head-on collision of two solitary
waves are derived. The effects of the magnetic field and its obliqueness, two different type of isothermal ions and the dust
particles adiabaticity are discussed. It is found that these factors significantly affect the phase shifts. 相似文献
10.
A TEST OF SIGNIFICANCE FOR PARTIAL LEAST SQUARES REGRESSION 总被引:1,自引:0,他引:1
IAN N. WAKELING JEFF J. MORRIS AFRC Institute of Food Research Earley Gate Whiteknights Ro Reading RG EF U.K.Zeneca Pharmaceuticals Mereside Alderley Park Macclesfiel Cheshire SK TG U.K. 《地理学报(英文版)》1993,(4)
Partial least squares (PLS) regression is a commonly used statistical technique for performingmultivariate calibration, especially in situations where there are more variables than samples. Choosingthe number of factors to include in a model is a decision that all users of PLS must make, but iscomplicated by the large number of empirical tests available. In most instances predictive ability is themost desired property of a PLS model and so interest has centred on making this choice based on aninternal validation process. A popular approach is the calculation of a cross-validated r~2 to gauge howmuch variance in the dependent variable can be explained from leave-one-out predictions. Using MonteCarlo simulations for different sizes of data set, the influence of chance effects on the cross-validationprocess is investigated. The results are presented as tables of critical values which are compared againstthe values of cross-validated r~2 obtained from the user's own data set. This gives a formal test forpredictive ability of a PLS model with a given number of dimensions. 相似文献