The design of Human Occupied Vehicle （HOV） is a typical multidisciplinary problem, but heavily dependent on the experience of naval architects at present engineering design. In order to relieve the experience depend...The design of Human Occupied Vehicle （HOV） is a typical multidisciplinary problem, but heavily dependent on the experience of naval architects at present engineering design. In order to relieve the experience dependence and improve the design, a new Multidisciplinary Design Optimization （MDO） method ＂Bi-Level Integrated System Collaborative Optimization （BLISCO）＂ is applied to the conceptual design of an HOV, which consists of hull module, resistance module, energy module, structure module, weight module, and the stability module. This design problem is defined by 21 design variables and 23 constraints, and its objective is to maximize the ratio of payload to weight. The results show that the general performance of the HOV can be greatly improved by BLISCO.展开更多
This paper presents our study of the nonlinear stability of a new anisotropic continuum traffic flow model in which the dimensionless parameter or anisotropic factor controls the non-isotropic character and diffusive ...This paper presents our study of the nonlinear stability of a new anisotropic continuum traffic flow model in which the dimensionless parameter or anisotropic factor controls the non-isotropic character and diffusive influence. In order to establish traff^c flow stability criterion or to know the critical parameters that lead, on one hand, to a stable response to perturbations or disturbances or, on the other hand, to an unstable response and therefore to a possible congestion, a nonlinear stability criterion is derived by using a wavefront expansion technique. The stability criterion is illustrated by numerical results using the finite difference method for two different values of anisotropic parameter. It is also been observed that the newly derived stability results are consistent with previously reported results obtained using approximate linearisation methods. Moreover, the stability criterion derived in this paper can provide more refined information from the perspective of the capability to reproduce nonlinear traffic flow behaviors observed in real traffic than previously established methodologies.展开更多
The present work is concerned with the solution of a problem on thermoelastic interactions in a functional graded material due to thermal shock in the context of the fractional order three-phase lag model. The governi...The present work is concerned with the solution of a problem on thermoelastic interactions in a functional graded material due to thermal shock in the context of the fractional order three-phase lag model. The governing equations of fractional order generalized thermoelasticity with three-phase lag model for functionally graded materials(FGM)(i.e., material with spatially varying material properties) are established. The analytical solution in the transform domain is obtained by using the eigenvalue approach.The inversion of Laplace transform is done numerically. The graphical results indicate that the fractional parameter has significant effects on all the physical quantities. Thus, we can consider the theory of fractional order generalized thermoelasticity an improvement on studying elastic materials.展开更多
In this article we investigate the flow of Sutterby liquid due to rotating stretchable disk. Mass and heat transport are analyzed through Brownian diffusion and thermophoresis. Further the effects of magnetic field, c...In this article we investigate the flow of Sutterby liquid due to rotating stretchable disk. Mass and heat transport are analyzed through Brownian diffusion and thermophoresis. Further the effects of magnetic field, chemical reaction and heat source are also accounted. We employ transformation procedure to obtain a system of nonlinear ODE's. This system is numerically solved by Built-in-Shooting method. Impacts of different involved parameter on velocity, temperature and concentration are described. Velocity, concentration and temperature gradients are numerically computed. Obtained results show that velocity is reduced through material parameter. Temperature and concentration are enhanced with thermophoresis parameter.展开更多
We present a general homogenization method a periodic heterogeneous material with piecewise constants for diffusion, heat conduction, and wave propagation in The method is relevant to the frequently encountered upsca...We present a general homogenization method a periodic heterogeneous material with piecewise constants for diffusion, heat conduction, and wave propagation in The method is relevant to the frequently encountered upscaling issues for heterogeneous materials. The dispersion relation for each problem is first expressed in the general form where the frequency co （or wavenumber k） is expanded in terms of the wavenumber k （or frequency ω）. A general homogenization model can be directly obtained with any given dispersion relation. Next step we study the unit cell of the heterogeneous material and derive the exact dispersion relation. The final homogenized equations include both leading order terms （effective properties） and high order contributions that represent the effect of the microscopic heterogeneity on the macroscopic behavior. That effect can be lumped into a single dimensionless heterogeneity parameter β, which is bounded between -1/12≤β≤ 0 and has a universal expression for all three problems. Numerical examples validate the proposed method and demonstrate a significant computational saving.展开更多
When pycnocline thickness of ocean density is relatively small, density stratification can be well represented as a two-layer system. In this article, a depth integrated model of the two-layer fluid with constant dens...When pycnocline thickness of ocean density is relatively small, density stratification can be well represented as a two-layer system. In this article, a depth integrated model of the two-layer fluid with constant density is considered,and a variant of the edge-based non-hydrostatic numerical scheme is formulated. The resulting scheme is very efficient since it resolves the vertical fluid depth only in two layers. Despite using just two layers, the numerical dispersion is shown to agree with the analytical dispersion curves over a wide range of kd, where k is the wave number and d the water depth. The scheme was tested by simulating an interfacial solitary wave propagating over a flat bottom, as well as over a bottom step. On a laboratory scale, the formation of an interfacial wave is simulated,which also shows the interaction of wave with a triangular bathymetry. Then, a case study using the Lombok Strait topography is discussed, and the results show the development of an interfacial wave due to a strong current passing through a sill.展开更多
Gallium phosphide （GAP） nanoparticulate thin films were easily fabricated by colloidal suspension deposition via GaP nanoparticles dispersed in N,N-dimethylformamide. The microstructure of the film was performed by ...Gallium phosphide （GAP） nanoparticulate thin films were easily fabricated by colloidal suspension deposition via GaP nanoparticles dispersed in N,N-dimethylformamide. The microstructure of the film was performed by x-ray diffraction, high resolution transmission electron microscopy and field emission scanning electron microscopy. The film was further investigated by spectroscopic ellipsometry. After the model GaP＋void[SiO2 was built and an effective medium approximation was adopted, the values of the refractive index n and the extinction coefficient k were calculated for the energy range of 0.75 eV-4.0 eV using the dispersion formula in DeltaPsi2 software. The absorption coefficient of the film was calculated from its k and its energy gaps were further estimated according to the Tauc equation, which were further verified by its fluorescence spectrum measurement. The structure and optical absorption properties of the nanoparticulate films are promising for their potential applications in hybrid solar cells.展开更多
The hierarchical reconstruction （HR） [Liu, Shu, Tadmor and Zhang, SINUM ＇07] has been successfully applied to prevent oscillations in solutions computed by finite volume, Runge-Kutta discontinuous Galerkin, spectra...The hierarchical reconstruction （HR） [Liu, Shu, Tadmor and Zhang, SINUM ＇07] has been successfully applied to prevent oscillations in solutions computed by finite volume, Runge-Kutta discontinuous Galerkin, spectral volume schemes for solving hyperbolic conservation laws. In this paper, we demonstrate that HR can also be combined with spectral/hp element method for solving hyperbolic conservation laws. An orthogonal spectral basis written in terms of Jacobi polynomials is applied. High computational efficiency is obtained due to such matrix-free algorithm. The formulation is conservative, and essential nomoscillation is enforced by the HR limiter. We show that HR preserves the order of accuracy of the spectral/hp element method for smooth solution problems and generate essentially non-oscillatory solutions profiles for capturing discontinuous solutions without local characteristic decomposition. In addition, we introduce a postprocessing technique to improve HR for limiting high degree numerical solutions.展开更多
The rotationally symmetric flow of a micropolar fluid in the presence of an infinite rotating disk has been studied numerically. The equations of motion are reduced to a system of ordinary differential equations, whic...The rotationally symmetric flow of a micropolar fluid in the presence of an infinite rotating disk has been studied numerically. The equations of motion are reduced to a system of ordinary differential equations, which in turn are solved numerically using SOR method and Simpson’s (1/3) rule. The results are calculated for different values of the parameter s (the ratio of angular velocities of disc and fluid) and the suction parameter a. Moreover, three different sets of the values of non-dimensional material constants related to micropolar behavior of the fluid have been chosen arbitrarily. The calculations have been carried out using three different grid sizes to check the accuracy of the results. The research concludes that the micropolar fluids flow resembles with that of Newtonian fluids when the material constants become close to zero. The comparison of these results is presented for possible values of the parameter s.展开更多
The disturbance due to mechanical and thermal sources in saturated porous media with incompressible fluid for two-dimensional axi-symmetric problem is investigated.The Laplace and Hankel transforms techniques are used...The disturbance due to mechanical and thermal sources in saturated porous media with incompressible fluid for two-dimensional axi-symmetric problem is investigated.The Laplace and Hankel transforms techniques are used to investigate the problem.The concentrated source and source over circular region have been taken to show the utility of the approach.The transformed components of displacement,stress and pore pressure are obtained.Numerical inversion techniques are used to obtain the resulting quantities in the physical domain and the effect of porosity is shown on the resulting quantities.All the field quantities are found to be sensitive towards the porosity parameters.It is observed that porosity parameters have both increasing and decreasing effect on the numerical values of the physical quantities.Also the values of the physical quantities are affected by the different boundaries.A special case of interest is also deduced.展开更多
This paper examines presence of some stylized facts of short-term stock prices in the banking sector of the Nigerian Stock Market (NSM). Non-normality, lack of autocorrelation in the returns at first lag and significa...This paper examines presence of some stylized facts of short-term stock prices in the banking sector of the Nigerian Stock Market (NSM). Non-normality, lack of autocorrelation in the returns at first lag and significant positive autocorrelation in higher magnitude returns, widely studied in other markets, are investigated using daily closing stock prices of the four major Nigerian banks (Access, First, Guaranty Trust and United Bank for Africa (UBA)), from 2001 to 2013;encompassing periods of different financial scenarios. Jarque-Bera (JB), Doonik-Hansen, Kolmogrov-Smirnov and Ljung-Box (Q) test statistics are applied. Our findings reveal that the four banks stocks behave slightly different, but generally possess the stylized facts found in other markets. Observed is that, while the distributions of the returns for two of these banks (First and UBA) are approximately symmetric and leptokurtic;those of Access and Guaranty Trust banks are significantly non-symmetric and leptokurtic, thus non-normally distributed. Also established is that, while autocorrelation functions of daily returns are either negative or zero, those of both absolute returns and the squared returns are mostly positive. The autocorrelations of absolute returns are found to be predominantly positive and more persistent than those of the squared returns;indicating volatility clustering. Consequently, we conclude that the short-term stock prices of these banks behave like those of other markets. Some implications of the results for financial investment and stock market behaviour in the banking sector of NSM are discussed.展开更多
Most stochastic modelling techniques neglect the correlations among the raw un-differenced observations when forming the variance-covariance matrix of the Global Navigation Satellite System(GNSS)observations.Some meth...Most stochastic modelling techniques neglect the correlations among the raw un-differenced observations when forming the variance-covariance matrix of the Global Navigation Satellite System(GNSS)observations.Some methods were developed to model these correlations.One such method is the Minimum Norm Quadratic Unbiased Estimator(MINQUE).Studies have shown that MINQUE improves ambiguity resolution,and ultimately,the positioning solution in short baselines.However,its effect in cases of processing with longer baselines and on the estimation of zenith wet delay(ZWD)is somewhat unknown.In this paper,a comparison between the impact of neglecting the correlations among the observations using an elevation-angle-dependent model(EADM)and modelling the correlations using MINQUE on height determination and ZWD for medium and long baselines is carried out.The initial testing was carried out across two Australian GNSS stations with a medium-length baseline throughout a three-week campaign.The results showed that using MINQUE did not resolve the coordinate,height and wet delay components as accurately as the EADM.The results were further verified with two long-baseline campaigns whereby EADM was also able to provide better wet delay estimates.The coordinate results were,however,mixed.Overall,the study concluded that the inclusion of the correlations among the observations,in general,do not improve the resolution of the coordinate and wet delay estimates.展开更多
In this paper we have constructed five dimensional Bianchi type-I cosmological model generated by a cloud of string with particles attached to them in Lyra manifold. Out of the two different cases, we obtained one cas...In this paper we have constructed five dimensional Bianchi type-I cosmological model generated by a cloud of string with particles attached to them in Lyra manifold. Out of the two different cases, we obtained one case leads to the five dimensional vacuum universe in Lyra manifold while the other case yields a string cosmological model in Lyra manifold. Some physical and geometrical properties of the models are briefly discussed.展开更多
Using 1200 CPUs of the National Supercomputer TH-A1 and a parallel integral algorithm based on the 3500th-order Taylor expansion and the 4180-digit multiple precision data,we have done a reliable simulation of chaotic...Using 1200 CPUs of the National Supercomputer TH-A1 and a parallel integral algorithm based on the 3500th-order Taylor expansion and the 4180-digit multiple precision data,we have done a reliable simulation of chaotic solution of Lorenz equation in a rather long interval 0 t 10000 LTU(Lorenz time unit).Such a kind of mathematically reliable chaotic simulation has never been reported.It provides us a numerical benchmark for mathematically reliable long-term prediction of chaos.Besides,it also proposes a safe method for mathematically reliable simulations of chaos in a finite but long enough interval.In addition,our very fine simulations suggest that such a kind of mathematically reliable long-term prediction of chaotic solution might have no physical meanings,because the inherent physical micro-level uncertainty due to thermal fluctuation might quickly transfer into macroscopic uncertainty so that trajectories for a long enough time would be essentially uncertain in physics.展开更多
In this paper,we study wave interaction with an emerged porous media.The governing equation is shallow water equations with a friction term of the linearized Dupuit-Forcheimer’s formula.From the continuity of surface...In this paper,we study wave interaction with an emerged porous media.The governing equation is shallow water equations with a friction term of the linearized Dupuit-Forcheimer’s formula.From the continuity of surface and horizontal flux,we derived the wave reflection and transmission coefficient formulas.They are similar with the corresponding formulas of the submerged solid bar breakwater.We solve the equations numerically using finite volume method on a staggered grid.The numerical wave reduction in the porous media confirms the analytical wave transmission curve.展开更多
Currently,the fifteen new periodic orbits of Newtonian three-body problem with equal mass were found by Suvakov and Dmitra sinovi[Phys Rev Lett,2013,110:114301]using the gradient descent method with double precision.I...Currently,the fifteen new periodic orbits of Newtonian three-body problem with equal mass were found by Suvakov and Dmitra sinovi[Phys Rev Lett,2013,110:114301]using the gradient descent method with double precision.In this paper,these reported orbits are checked stringently by means of a reliable numerical approach(namely the"Clean Numerical Simulation",CNS),which is based on the arbitrary-order Taylor series method and data in arbitrary-digit precision with a procedure of solution verification.It is found that seven among these fifteen orbits greatly depart from the periodic ones within a long enough interval of time,and are thus most possibly unstable at least.It is suggested to carefully check whether or not these seven unstable orbits are the so-called"computational periodicity"mentioned by Lorenz in 2006.This work also illustrates the validity and great potential of the CNS for chaotic dynamic systems.展开更多
One of the most prominent features of quantum entanglement is its invariability under local unitary transformations,which implies that the degree of entanglement or nonseparability remains constant during free-space p...One of the most prominent features of quantum entanglement is its invariability under local unitary transformations,which implies that the degree of entanglement or nonseparability remains constant during free-space propagation,true for both quantum and classically entangled modes.Here we demonstrate an exception to this rule using a carefully engineered vectorial light field,and we study its nonseparability dynamics upon free-space propagation.We show that the local nonseparability between the spatial and polarization degrees of freedom dramatically decays to zero while preserving the purity of the state and hence the global nonseparability.We show this by numerical simulations and corroborate it experimentally.Our results evince novel properties of classically entangled modes and point to the need for new measures of nonseparability for such vectorial fields,while paving the way for novel applications for customized structured light.展开更多
The thermal and velocity slips of boundary layer of Williamson nanofluid over a stretching sheet are studied numerically.Buongiorno model is used to explore the heat transfer phenomena caused by Brownian motion and th...The thermal and velocity slips of boundary layer of Williamson nanofluid over a stretching sheet are studied numerically.Buongiorno model is used to explore the heat transfer phenomena caused by Brownian motion and thermophoresis.Using similarity transformations,the governing equations are reduced to a set of nonlinear ordinary differential equations(ODEs).These equations are solved numerically by using Shooting method.The effects of non-Newtonian Williamson parameter,velocity and thermal slip parameters,Prandtl number,Brownian parameter,Schmidt number,Lewis number,Brownian motion parameter,thermophoresis parameter on velocity,temperature and concentration fields are shown graphically and discussed.The results found that the thickness of boundary layer decreases as the slip and thermal factor parameter increases.Further,present results indicate that the nanofluid temperature and concentration are enhanced with a rise of Williamson parameter.The Nusselt number is reduced with an increase of the Lewis and Prandtl numbers.展开更多
The birth of new genes in genomes is an important evolutionary event. Several studies reveal that new genes in animals tend to be preferentially expressed in male reproductive tissues such as testis （Betrdn et ah, 20...The birth of new genes in genomes is an important evolutionary event. Several studies reveal that new genes in animals tend to be preferentially expressed in male reproductive tissues such as testis （Betrdn et ah, 2002; Begun et ah, 2007; Dubruille et ah, 2012）, and thus an ＂out of testis＂ hypothesis for the emergence of new genes has been proposed （Vinckenbosch et ah, 2006; Kaessmann, 2010）. However, such phenomena have not been examined in plant species. Here, by employing a phylostratigraphic method, we dated the origin of protein-coding genes in rice and Arabidopsis thaliana and observed a num- ber of young genes in both species. These young genes tend to encode short extracellular proteins, which may be involved in rapid evolving processes, such as reproductive barriers, species specification, and anti- microbial processes. Further analysis of transcriptome age indexes across different tissues revealed that male reproductive cells express a phylogenetically younger transcriptome than other plant tissues. Compared with sporophytic tissues, the young transcriptomes of the male gametophyte displayed greater complexity and diversity, which included a higher ratio of anti-sense and inter-genic transcripts, reflecting a pervasive transcription state that facilitated the emergence of new genes. Here, we propose that pollen may act as an ＂innovation incubator＂ for the birth of de novo genes. With cases of male-biased expression of young genes reported in animals, the ＂new genes out of the male＂ model revealed a common evolu- tionary force that drives reproductive barriers, species specification, and the upgrading of defensive mech- anisms against pathogens.展开更多
基金financially supported by the National Natural Science Foundation of China(Grant No.51109132)the Specialized Research Fund for the Doctoral Program of Higher Education of China(Grant No.20110073120015)
文摘The design of Human Occupied Vehicle （HOV） is a typical multidisciplinary problem, but heavily dependent on the experience of naval architects at present engineering design. In order to relieve the experience dependence and improve the design, a new Multidisciplinary Design Optimization （MDO） method ＂Bi-Level Integrated System Collaborative Optimization （BLISCO）＂ is applied to the conceptual design of an HOV, which consists of hull module, resistance module, energy module, structure module, weight module, and the stability module. This design problem is defined by 21 design variables and 23 constraints, and its objective is to maximize the ratio of payload to weight. The results show that the general performance of the HOV can be greatly improved by BLISCO.
文摘This paper presents our study of the nonlinear stability of a new anisotropic continuum traffic flow model in which the dimensionless parameter or anisotropic factor controls the non-isotropic character and diffusive influence. In order to establish traff^c flow stability criterion or to know the critical parameters that lead, on one hand, to a stable response to perturbations or disturbances or, on the other hand, to an unstable response and therefore to a possible congestion, a nonlinear stability criterion is derived by using a wavefront expansion technique. The stability criterion is illustrated by numerical results using the finite difference method for two different values of anisotropic parameter. It is also been observed that the newly derived stability results are consistent with previously reported results obtained using approximate linearisation methods. Moreover, the stability criterion derived in this paper can provide more refined information from the perspective of the capability to reproduce nonlinear traffic flow behaviors observed in real traffic than previously established methodologies.
文摘The present work is concerned with the solution of a problem on thermoelastic interactions in a functional graded material due to thermal shock in the context of the fractional order three-phase lag model. The governing equations of fractional order generalized thermoelasticity with three-phase lag model for functionally graded materials(FGM)(i.e., material with spatially varying material properties) are established. The analytical solution in the transform domain is obtained by using the eigenvalue approach.The inversion of Laplace transform is done numerically. The graphical results indicate that the fractional parameter has significant effects on all the physical quantities. Thus, we can consider the theory of fractional order generalized thermoelasticity an improvement on studying elastic materials.
文摘In this article we investigate the flow of Sutterby liquid due to rotating stretchable disk. Mass and heat transport are analyzed through Brownian diffusion and thermophoresis. Further the effects of magnetic field, chemical reaction and heat source are also accounted. We employ transformation procedure to obtain a system of nonlinear ODE's. This system is numerically solved by Built-in-Shooting method. Impacts of different involved parameter on velocity, temperature and concentration are described. Velocity, concentration and temperature gradients are numerically computed. Obtained results show that velocity is reduced through material parameter. Temperature and concentration are enhanced with thermophoresis parameter.
文摘We present a general homogenization method a periodic heterogeneous material with piecewise constants for diffusion, heat conduction, and wave propagation in The method is relevant to the frequently encountered upscaling issues for heterogeneous materials. The dispersion relation for each problem is first expressed in the general form where the frequency co （or wavenumber k） is expanded in terms of the wavenumber k （or frequency ω）. A general homogenization model can be directly obtained with any given dispersion relation. Next step we study the unit cell of the heterogeneous material and derive the exact dispersion relation. The final homogenized equations include both leading order terms （effective properties） and high order contributions that represent the effect of the microscopic heterogeneity on the macroscopic behavior. That effect can be lumped into a single dimensionless heterogeneity parameter β, which is bounded between -1/12≤β≤ 0 and has a universal expression for all three problems. Numerical examples validate the proposed method and demonstrate a significant computational saving.
基金financially supported by the Institut Teknologi Bandung Research(Grant No.107a/I1.C01/PL/2017)
文摘When pycnocline thickness of ocean density is relatively small, density stratification can be well represented as a two-layer system. In this article, a depth integrated model of the two-layer fluid with constant density is considered,and a variant of the edge-based non-hydrostatic numerical scheme is formulated. The resulting scheme is very efficient since it resolves the vertical fluid depth only in two layers. Despite using just two layers, the numerical dispersion is shown to agree with the analytical dispersion curves over a wide range of kd, where k is the wave number and d the water depth. The scheme was tested by simulating an interfacial solitary wave propagating over a flat bottom, as well as over a bottom step. On a laboratory scale, the formation of an interfacial wave is simulated,which also shows the interaction of wave with a triangular bathymetry. Then, a case study using the Lombok Strait topography is discussed, and the results show the development of an interfacial wave due to a strong current passing through a sill.
文摘Gallium phosphide （GAP） nanoparticulate thin films were easily fabricated by colloidal suspension deposition via GaP nanoparticles dispersed in N,N-dimethylformamide. The microstructure of the film was performed by x-ray diffraction, high resolution transmission electron microscopy and field emission scanning electron microscopy. The film was further investigated by spectroscopic ellipsometry. After the model GaP＋void[SiO2 was built and an effective medium approximation was adopted, the values of the refractive index n and the extinction coefficient k were calculated for the energy range of 0.75 eV-4.0 eV using the dispersion formula in DeltaPsi2 software. The absorption coefficient of the film was calculated from its k and its energy gaps were further estimated according to the Tauc equation, which were further verified by its fluorescence spectrum measurement. The structure and optical absorption properties of the nanoparticulate films are promising for their potential applications in hybrid solar cells.
基金Research was supported in part by NSF grant DMS-0800612Research was supported by Applied Mathematics program of the US DOE Office of Advanced Scientific Computing ResearchThe Pacific Northwest National Laboratory is operated by Battelle for the U.S. Department of Energy under Contract DE-AC05-76RL01830
文摘The hierarchical reconstruction （HR） [Liu, Shu, Tadmor and Zhang, SINUM ＇07] has been successfully applied to prevent oscillations in solutions computed by finite volume, Runge-Kutta discontinuous Galerkin, spectral volume schemes for solving hyperbolic conservation laws. In this paper, we demonstrate that HR can also be combined with spectral/hp element method for solving hyperbolic conservation laws. An orthogonal spectral basis written in terms of Jacobi polynomials is applied. High computational efficiency is obtained due to such matrix-free algorithm. The formulation is conservative, and essential nomoscillation is enforced by the HR limiter. We show that HR preserves the order of accuracy of the spectral/hp element method for smooth solution problems and generate essentially non-oscillatory solutions profiles for capturing discontinuous solutions without local characteristic decomposition. In addition, we introduce a postprocessing technique to improve HR for limiting high degree numerical solutions.
文摘The rotationally symmetric flow of a micropolar fluid in the presence of an infinite rotating disk has been studied numerically. The equations of motion are reduced to a system of ordinary differential equations, which in turn are solved numerically using SOR method and Simpson’s (1/3) rule. The results are calculated for different values of the parameter s (the ratio of angular velocities of disc and fluid) and the suction parameter a. Moreover, three different sets of the values of non-dimensional material constants related to micropolar behavior of the fluid have been chosen arbitrarily. The calculations have been carried out using three different grid sizes to check the accuracy of the results. The research concludes that the micropolar fluids flow resembles with that of Newtonian fluids when the material constants become close to zero. The comparison of these results is presented for possible values of the parameter s.
文摘The disturbance due to mechanical and thermal sources in saturated porous media with incompressible fluid for two-dimensional axi-symmetric problem is investigated.The Laplace and Hankel transforms techniques are used to investigate the problem.The concentrated source and source over circular region have been taken to show the utility of the approach.The transformed components of displacement,stress and pore pressure are obtained.Numerical inversion techniques are used to obtain the resulting quantities in the physical domain and the effect of porosity is shown on the resulting quantities.All the field quantities are found to be sensitive towards the porosity parameters.It is observed that porosity parameters have both increasing and decreasing effect on the numerical values of the physical quantities.Also the values of the physical quantities are affected by the different boundaries.A special case of interest is also deduced.
文摘This paper examines presence of some stylized facts of short-term stock prices in the banking sector of the Nigerian Stock Market (NSM). Non-normality, lack of autocorrelation in the returns at first lag and significant positive autocorrelation in higher magnitude returns, widely studied in other markets, are investigated using daily closing stock prices of the four major Nigerian banks (Access, First, Guaranty Trust and United Bank for Africa (UBA)), from 2001 to 2013;encompassing periods of different financial scenarios. Jarque-Bera (JB), Doonik-Hansen, Kolmogrov-Smirnov and Ljung-Box (Q) test statistics are applied. Our findings reveal that the four banks stocks behave slightly different, but generally possess the stylized facts found in other markets. Observed is that, while the distributions of the returns for two of these banks (First and UBA) are approximately symmetric and leptokurtic;those of Access and Guaranty Trust banks are significantly non-symmetric and leptokurtic, thus non-normally distributed. Also established is that, while autocorrelation functions of daily returns are either negative or zero, those of both absolute returns and the squared returns are mostly positive. The autocorrelations of absolute returns are found to be predominantly positive and more persistent than those of the squared returns;indicating volatility clustering. Consequently, we conclude that the short-term stock prices of these banks behave like those of other markets. Some implications of the results for financial investment and stock market behaviour in the banking sector of NSM are discussed.
基金This work was completed under a scholarship from Curtin University of Technology,Perth,Australia and through Australian Research Council APAI grant LP0347723 in collaboration with the Australian Bureau of Meteorology.
文摘Most stochastic modelling techniques neglect the correlations among the raw un-differenced observations when forming the variance-covariance matrix of the Global Navigation Satellite System(GNSS)observations.Some methods were developed to model these correlations.One such method is the Minimum Norm Quadratic Unbiased Estimator(MINQUE).Studies have shown that MINQUE improves ambiguity resolution,and ultimately,the positioning solution in short baselines.However,its effect in cases of processing with longer baselines and on the estimation of zenith wet delay(ZWD)is somewhat unknown.In this paper,a comparison between the impact of neglecting the correlations among the observations using an elevation-angle-dependent model(EADM)and modelling the correlations using MINQUE on height determination and ZWD for medium and long baselines is carried out.The initial testing was carried out across two Australian GNSS stations with a medium-length baseline throughout a three-week campaign.The results showed that using MINQUE did not resolve the coordinate,height and wet delay components as accurately as the EADM.The results were further verified with two long-baseline campaigns whereby EADM was also able to provide better wet delay estimates.The coordinate results were,however,mixed.Overall,the study concluded that the inclusion of the correlations among the observations,in general,do not improve the resolution of the coordinate and wet delay estimates.
文摘In this paper we have constructed five dimensional Bianchi type-I cosmological model generated by a cloud of string with particles attached to them in Lyra manifold. Out of the two different cases, we obtained one case leads to the five dimensional vacuum universe in Lyra manifold while the other case yields a string cosmological model in Lyra manifold. Some physical and geometrical properties of the models are briefly discussed.
基金partly supported by National Natural Science Foundation of China (Grant No. 11272209)National Basic Research Program of China (Grant No. 2011CB309704)State Key Laboratory of Ocean Engineering of China (Grant No. GKZD010056).
文摘Using 1200 CPUs of the National Supercomputer TH-A1 and a parallel integral algorithm based on the 3500th-order Taylor expansion and the 4180-digit multiple precision data,we have done a reliable simulation of chaotic solution of Lorenz equation in a rather long interval 0 t 10000 LTU(Lorenz time unit).Such a kind of mathematically reliable chaotic simulation has never been reported.It provides us a numerical benchmark for mathematically reliable long-term prediction of chaos.Besides,it also proposes a safe method for mathematically reliable simulations of chaos in a finite but long enough interval.In addition,our very fine simulations suggest that such a kind of mathematically reliable long-term prediction of chaotic solution might have no physical meanings,because the inherent physical micro-level uncertainty due to thermal fluctuation might quickly transfer into macroscopic uncertainty so that trajectories for a long enough time would be essentially uncertain in physics.
基金We acknowledge financial support from riset dan inovasi KK ITB 122.21/ALJ/DIPA/PN/SPK/2013partially support from Riset Disentralisasi 1063c/l1.C01.2/PL/2014.
文摘In this paper,we study wave interaction with an emerged porous media.The governing equation is shallow water equations with a friction term of the linearized Dupuit-Forcheimer’s formula.From the continuity of surface and horizontal flux,we derived the wave reflection and transmission coefficient formulas.They are similar with the corresponding formulas of the submerged solid bar breakwater.We solve the equations numerically using finite volume method on a staggered grid.The numerical wave reduction in the porous media confirms the analytical wave transmission curve.
基金supported by the National Natural Science Foundation of China (Grant No.11272209)the Deanship of Scientific Research (DSR),King Abdulaziz University (KAU) (Grant No.37-130-35-HiCi)
文摘Currently,the fifteen new periodic orbits of Newtonian three-body problem with equal mass were found by Suvakov and Dmitra sinovi[Phys Rev Lett,2013,110:114301]using the gradient descent method with double precision.In this paper,these reported orbits are checked stringently by means of a reliable numerical approach(namely the"Clean Numerical Simulation",CNS),which is based on the arbitrary-order Taylor series method and data in arbitrary-digit precision with a procedure of solution verification.It is found that seven among these fifteen orbits greatly depart from the periodic ones within a long enough interval of time,and are thus most possibly unstable at least.It is suggested to carefully check whether or not these seven unstable orbits are the so-called"computational periodicity"mentioned by Lorenz in 2006.This work also illustrates the validity and great potential of the CNS for chaotic dynamic systems.
基金Consejo Nacional de Ciencia y Tecnología(PN2016-3140)National Natural Science Foundation of China(61975047).
文摘One of the most prominent features of quantum entanglement is its invariability under local unitary transformations,which implies that the degree of entanglement or nonseparability remains constant during free-space propagation,true for both quantum and classically entangled modes.Here we demonstrate an exception to this rule using a carefully engineered vectorial light field,and we study its nonseparability dynamics upon free-space propagation.We show that the local nonseparability between the spatial and polarization degrees of freedom dramatically decays to zero while preserving the purity of the state and hence the global nonseparability.We show this by numerical simulations and corroborate it experimentally.Our results evince novel properties of classically entangled modes and point to the need for new measures of nonseparability for such vectorial fields,while paving the way for novel applications for customized structured light.
基金The authors gratefully acknowledge the financial supports received from Ministry of Higher Education,University Malaysia Pahang(UMP),Malaysia,through vote number RDU 150101 and RDU 170358.The second author would like to acknowledge Ton Duc Thang University,Ho Chi Minh City,Vietnam for the financial support.
文摘The thermal and velocity slips of boundary layer of Williamson nanofluid over a stretching sheet are studied numerically.Buongiorno model is used to explore the heat transfer phenomena caused by Brownian motion and thermophoresis.Using similarity transformations,the governing equations are reduced to a set of nonlinear ordinary differential equations(ODEs).These equations are solved numerically by using Shooting method.The effects of non-Newtonian Williamson parameter,velocity and thermal slip parameters,Prandtl number,Brownian parameter,Schmidt number,Lewis number,Brownian motion parameter,thermophoresis parameter on velocity,temperature and concentration fields are shown graphically and discussed.The results found that the thickness of boundary layer decreases as the slip and thermal factor parameter increases.Further,present results indicate that the nanofluid temperature and concentration are enhanced with a rise of Williamson parameter.The Nusselt number is reduced with an increase of the Lewis and Prandtl numbers.
文摘The birth of new genes in genomes is an important evolutionary event. Several studies reveal that new genes in animals tend to be preferentially expressed in male reproductive tissues such as testis （Betrdn et ah, 2002; Begun et ah, 2007; Dubruille et ah, 2012）, and thus an ＂out of testis＂ hypothesis for the emergence of new genes has been proposed （Vinckenbosch et ah, 2006; Kaessmann, 2010）. However, such phenomena have not been examined in plant species. Here, by employing a phylostratigraphic method, we dated the origin of protein-coding genes in rice and Arabidopsis thaliana and observed a num- ber of young genes in both species. These young genes tend to encode short extracellular proteins, which may be involved in rapid evolving processes, such as reproductive barriers, species specification, and anti- microbial processes. Further analysis of transcriptome age indexes across different tissues revealed that male reproductive cells express a phylogenetically younger transcriptome than other plant tissues. Compared with sporophytic tissues, the young transcriptomes of the male gametophyte displayed greater complexity and diversity, which included a higher ratio of anti-sense and inter-genic transcripts, reflecting a pervasive transcription state that facilitated the emergence of new genes. Here, we propose that pollen may act as an ＂innovation incubator＂ for the birth of de novo genes. With cases of male-biased expression of young genes reported in animals, the ＂new genes out of the male＂ model revealed a common evolu- tionary force that drives reproductive barriers, species specification, and the upgrading of defensive mech- anisms against pathogens.
