In this paper,the existence,uniqueness,asymptotic and global exponential stability of pseudo almost automorphic solution for a class of delayed Lasota-Wazewska model with impulsive effects are established by applying ...In this paper,the existence,uniqueness,asymptotic and global exponential stability of pseudo almost automorphic solution for a class of delayed Lasota-Wazewska model with impulsive effects are established by applying an appropriate fixed point theorem and Lyapunov functional method.Finally,a numerical example with simulation is given to illuminate our theoretical results.展开更多
Observations of the second solar spectrum(SSS) revealed the existence of prominent linear polarization signals due to lines of the C2 molecule.Interpretation of the SSS is the only tool to obtain the weak and turbulen...Observations of the second solar spectrum(SSS) revealed the existence of prominent linear polarization signals due to lines of the C2 molecule.Interpretation of the SSS is the only tool to obtain the weak and turbulent magnetic field which is widespread in the Quiet Sun.However,this interpretation is conditioned by the determination of accurate collisional data.In this context,we present a formulation of the problem of the calculation of the polarization transfer rates by collisions of polarized C2 states with electrons.The obtained formulae are applied to determine,for the first time,the polarization transfer rates between the C2 states of the Swan band electronic system(a 3Πu d 3Πq) and electrons for temperatures going up from 1000 to 10000 K.However,due to the closeness of the electronic states of the C2 molecule,the two electronic d 3Πg and a 3Πu cannot be disconnected from the other electronic levels and,thus,a model based on only two states is not sufficient to describe the formation of the lines in the Swan band.Consequently,we also calculated the collisional polarization transfer rates in the case where the first eight electronic states of C2 are taken into account.All rates are given as functions of the temperature by power laws.Our results should be useful for future solar applications.展开更多
Scattering of anisotropic radiation by atoms,ions or molecules is sufficient to generate linear polarization observable in stars and planets’atmospheres,circumstellar environments,and in particular in the Sun’s atmo...Scattering of anisotropic radiation by atoms,ions or molecules is sufficient to generate linear polarization observable in stars and planets’atmospheres,circumstellar environments,and in particular in the Sun’s atmosphere.This kind of polarization is called scattering polarization(SP)or second solar spectrum(SSS)if it is formed near the limb of the solar photosphere.Generation of linear SP can typically be reached more easily than circular SP.Interestingly,the latter is often absent in observations and theories.Intrigued by this,we propose to demonstrate how circular SP can be created by anisotropic collisions if a magnetic field is present.We also demonstrate how anisotropic collisions can result in the creation of circular SP if the radiation field is anisotropic.We show that under certain conditions,linear SP creation is accompanied by the emergence of circular SP which can be useful for diagnostics of solar and astrophysical plasmas.We treat an example and calculate the density matrix elements of tensorial order k=1 which are directly associated with the presence of circular SP.This work should encourage theoretical and observational research to be increasingly oriented towards circular SP profiles in addition to linear SP in order to improve our analysis tools of astrophysical and solar observations.展开更多
In this work, we numerically study the laminar mixed convection of fluid flow in a vertical channel filled with porous media during the drying process. The porous medium, modeled as a vertical wall, consists of solid ...In this work, we numerically study the laminar mixed convection of fluid flow in a vertical channel filled with porous media during the drying process. The porous medium, modeled as a vertical wall, consists of solid and nanofluid phase (Water-Al2O3 or Water-Cu), as well as a gas phase. The established model is developed based on Whitaker’s theory and resolved by our numerical code using Fortran. Results principally show the influence of various physical parameters, such as nanoparticle volume fraction, ambient temperature, and saturation on heat and mass transfer on the drying process. This study brings the effect of the presence of nanofluids in porous media. It contributes not only to our fundamental understanding of drying processes but also provides practical insights that can guide the development of more efficient and sustainable drying technologies. .展开更多
Purpose–The purpose of this paper is to investigate the stabilization of unstable periodic orbits of Chua’s system using adaptive fuzzy sliding mode controllers with moving surface.Design/methodology/approach–For t...Purpose–The purpose of this paper is to investigate the stabilization of unstable periodic orbits of Chua’s system using adaptive fuzzy sliding mode controllers with moving surface.Design/methodology/approach–For this aim,the sliding mode controller and fuzzy systems are combined to achieve the stabilization.Then,the authors propose a moving sliding surface to improve robustness against uncertainties during the reaching phase,parameter variations and extraneous disturbances.Findings–Afterward,the authors design a sliding observer to estimate the unmeasurable states which are used in the previously designed controller.Originality/value–Numerical results are provided to show the effectiveness and robustness of the proposed method.展开更多
文摘In this paper,the existence,uniqueness,asymptotic and global exponential stability of pseudo almost automorphic solution for a class of delayed Lasota-Wazewska model with impulsive effects are established by applying an appropriate fixed point theorem and Lyapunov functional method.Finally,a numerical example with simulation is given to illuminate our theoretical results.
基金funded by the Deanship of Scientific Research(DSR)at King Abdulaziz University,Jeddah,under grant no.G:426–130–1440DSR for technical and financial support。
文摘Observations of the second solar spectrum(SSS) revealed the existence of prominent linear polarization signals due to lines of the C2 molecule.Interpretation of the SSS is the only tool to obtain the weak and turbulent magnetic field which is widespread in the Quiet Sun.However,this interpretation is conditioned by the determination of accurate collisional data.In this context,we present a formulation of the problem of the calculation of the polarization transfer rates by collisions of polarized C2 states with electrons.The obtained formulae are applied to determine,for the first time,the polarization transfer rates between the C2 states of the Swan band electronic system(a 3Πu d 3Πq) and electrons for temperatures going up from 1000 to 10000 K.However,due to the closeness of the electronic states of the C2 molecule,the two electronic d 3Πg and a 3Πu cannot be disconnected from the other electronic levels and,thus,a model based on only two states is not sufficient to describe the formation of the lines in the Swan band.Consequently,we also calculated the collisional polarization transfer rates in the case where the first eight electronic states of C2 are taken into account.All rates are given as functions of the temperature by power laws.Our results should be useful for future solar applications.
基金funded by the Deanship of Scientific Research(DSR)at King Abdulaziz University,Jeddah,under grant no.(G:348-1301440)DSR for technical and financial support。
文摘Scattering of anisotropic radiation by atoms,ions or molecules is sufficient to generate linear polarization observable in stars and planets’atmospheres,circumstellar environments,and in particular in the Sun’s atmosphere.This kind of polarization is called scattering polarization(SP)or second solar spectrum(SSS)if it is formed near the limb of the solar photosphere.Generation of linear SP can typically be reached more easily than circular SP.Interestingly,the latter is often absent in observations and theories.Intrigued by this,we propose to demonstrate how circular SP can be created by anisotropic collisions if a magnetic field is present.We also demonstrate how anisotropic collisions can result in the creation of circular SP if the radiation field is anisotropic.We show that under certain conditions,linear SP creation is accompanied by the emergence of circular SP which can be useful for diagnostics of solar and astrophysical plasmas.We treat an example and calculate the density matrix elements of tensorial order k=1 which are directly associated with the presence of circular SP.This work should encourage theoretical and observational research to be increasingly oriented towards circular SP profiles in addition to linear SP in order to improve our analysis tools of astrophysical and solar observations.
文摘In this work, we numerically study the laminar mixed convection of fluid flow in a vertical channel filled with porous media during the drying process. The porous medium, modeled as a vertical wall, consists of solid and nanofluid phase (Water-Al2O3 or Water-Cu), as well as a gas phase. The established model is developed based on Whitaker’s theory and resolved by our numerical code using Fortran. Results principally show the influence of various physical parameters, such as nanoparticle volume fraction, ambient temperature, and saturation on heat and mass transfer on the drying process. This study brings the effect of the presence of nanofluids in porous media. It contributes not only to our fundamental understanding of drying processes but also provides practical insights that can guide the development of more efficient and sustainable drying technologies. .
文摘Purpose–The purpose of this paper is to investigate the stabilization of unstable periodic orbits of Chua’s system using adaptive fuzzy sliding mode controllers with moving surface.Design/methodology/approach–For this aim,the sliding mode controller and fuzzy systems are combined to achieve the stabilization.Then,the authors propose a moving sliding surface to improve robustness against uncertainties during the reaching phase,parameter variations and extraneous disturbances.Findings–Afterward,the authors design a sliding observer to estimate the unmeasurable states which are used in the previously designed controller.Originality/value–Numerical results are provided to show the effectiveness and robustness of the proposed method.
