In this paper we propose a novel diffusion quantum Monte Carlo algo-rithm, it is a self-optimizing and self-improving procedure. The method has been em-ployed to calculate the potential energy curve of C2. The total e...In this paper we propose a novel diffusion quantum Monte Carlo algo-rithm, it is a self-optimizing and self-improving procedure. The method has been em-ployed to calculate the potential energy curve of C2. The total energies for the X 1Σg+state of C2 were calculated at seven values of the bond length: 0. 106, 0. 111, 0. 124,0. 132, 0. 143, 0. 159 and 0. 185 nm; and a smooth potential energy curve was ob-tained, because when the self-optimizing technique is used, the statistical error decreas-es tremendously. The calculation results on the potential energy curve of C2 show thatthe self-optimizing diffusion quantum Monte Carlo method proposed in the present pa-per is successful.展开更多
Objective To accurately extract pulmonary vessels on medical images. Methods An efficient vessel segmentation framework is presented, which includes a smoothing method and a extraction algorithm. The smoothing method ...Objective To accurately extract pulmonary vessels on medical images. Methods An efficient vessel segmentation framework is presented, which includes a smoothing method and a extraction algorithm. The smoothing method is based on an improved coherence diffusion approach that integrates the second-order directional differential information. It can analyze weak edges such as narrow peak or ridge-like structures. Meanwhile, an improved extraction algorithm is proposed. It is based on a fast marching algorithm where a sorted sequence array and multi-initialization technique are applied. Results The improved coherence diffusion approach can precisely preserve important oriented patterns and remove noises on the images. Experimental results on several images show that the proposed method can effectively find the location of pulmonary vessels. Conclusion The segmentation method is accurate and fast that can be a useful tool for medical imaging applications.展开更多
Potential energy curves for the lowest electronic states of LaB and LaB- have been calculated by ab initio calculations.The diffusion Monte Carlo method has been employed in combination with three different trial func...Potential energy curves for the lowest electronic states of LaB and LaB- have been calculated by ab initio calculations.The diffusion Monte Carlo method has been employed in combination with three different trial functions. Spectroscopic constants have also been numerically derived for the neutral molecule and compared with the only available theoretical work;^（[19]） however, predictions are provided for the corresponding constants for the anionic species which have not been reported yet. Our calculations suggest the high spin quintet state of LaB as the ground state with the triplet state higher in energy irrespective of the type of the functional used. This suggestion is in good accordance with the previous theoretical results calculated at B3LYP/LANL2DZ level of theory, whereas it contradicts with the prediction based upon B3LYP/SDD calculations in the same study. Moreover, variations of the permanent dipole moments as a function of the internuclear separations for the two electronic states of the neutral molecule have been studied and analyzed.展开更多
The influence of initial placement of molecular or ion substance is investigated on the diffusion fluxes across the cell membrane. The diffusion fluxes and recovery curves are obtained by considering both the singlesp...The influence of initial placement of molecular or ion substance is investigated on the diffusion fluxes across the cell membrane. The diffusion fluxes and recovery curves are obtained by considering both the singlespot and double-spot concentrations inside the cell membrane. The results show that the additional concentration inside the membrane reduces the net fluxes at the cell interior as well as the exterior. In addition, it is found that the change in diffusion flux at the two outer walls of the membrane by the two-spot concentrations in the cell membrane is weaker than that of the single-spot concentration at the center. The variation of the influence of initial locations of the molecular concentrations inside the cell membrane on the diffusion fluxes is also discussed. This result can be applied to the diffusion process in avascular collagenous tissues.展开更多
Remote sensing images carry crucial ground information,often involving the spatial distribution and spatiotemporal changes of surface elements.To safeguard this sensitive data,image encryption technology is essential....Remote sensing images carry crucial ground information,often involving the spatial distribution and spatiotemporal changes of surface elements.To safeguard this sensitive data,image encryption technology is essential.In this paper,a novel Fibonacci sine exponential map is designed,the hyperchaotic performance of which is particularly suitable for image encryption algorithms.An encryption algorithm tailored for handling the multi-band attributes of remote sensing images is proposed.The algorithm combines a three-dimensional synchronized scrambled diffusion operation with chaos to efficiently encrypt multiple images.Moreover,the keys are processed using an elliptic curve cryptosystem,eliminating the need for an additional channel to transmit the keys,thus enhancing security.Experimental results and algorithm analysis demonstrate that the algorithm offers strong security and high efficiency,making it suitable for remote sensing image encryption tasks.展开更多
Curved microchannels are often encountered in lab-on-chip systems because the effective axial channel lengths of such channels are often larger than those of straight microchannels for a given per unit chip length.In ...Curved microchannels are often encountered in lab-on-chip systems because the effective axial channel lengths of such channels are often larger than those of straight microchannels for a given per unit chip length.In this paper,the effective diffusivity of a neutral solute in an oscillating electromagnetohydrodynamic(EMHD)flow through a curved rectangular microchannel is investigated theoretically.The flow is assumed as a creeping flow due to the extremely low Reynolds number in such microflow systems.Through the theoretical analysis,we find that the effective diffusivity primarily depends on five dimensionless parameters,i.e.,the curvature ratio of the curved channel,the Schmidt number,the tidal displacement,the angular Reynolds number,and the dimensionless electric field strength parameter.Based on the obtained results,we can precisely control the mass transfer characteristics of the EMHD flow in a curved rectangular microchannel by appropriately altering the corresponding parameter values.展开更多
Diffusion curves can be used to generate vector graphics images with smooth variation by solving Poisson equations. However, using the classical diffusion curve model, it is difficult to ensure that the generated diff...Diffusion curves can be used to generate vector graphics images with smooth variation by solving Poisson equations. However, using the classical diffusion curve model, it is difficult to ensure that the generated diffusion image satisfies desired constraints. In this paper, we develop a model for producing a diffusion image by solving a diffusion equation with diffusion coefficients, in which color layers and coefficient layers are introduced to facilitate the generation of the diffusion image. Doing so allows us to impose various constraints on the diffusion image, such as diffusion strength, diffusion direction,diffusion points, etc., in a unified computational framework. Various examples are presented in this paper to illustrate the capabilities of our model.展开更多
This study deals with the features of the mass and heat transport mechanism by adopting a modified version of Fourier and Fick’s model known as the CattaneoChristov double diffusive theory.The time-dependent magnetoh...This study deals with the features of the mass and heat transport mechanism by adopting a modified version of Fourier and Fick’s model known as the CattaneoChristov double diffusive theory.The time-dependent magnetohydrodynamic(MHD)flow of the Eyring-Powell liquid across an oscillatory stretchable curved sheet in the presence of Fourier and Fick’s model is investigated.The acquired set of flow equations is transformed into the form of nonlinear partial differential equations(PDEs)by applying appropriate similarity variables.A convergent series solution to the developed nonlinear equations is accomplished with the help of an analytical approach,i.e.,the homotopy analysis method(HAM).The consequences of diverse parameters,including the dimensionless EyringPowell liquid parameter,the radius of curvature,the Schmidt/Prandtl numbers,the ratio of the oscillatory frequency of the sheet to its stretchable rate constant,the mass and thermal relaxation variables involved in the flow,and the heat and mass properties,are displayed through graphs and tables.It is noted from this study that the amplitude of the pressure distribution rises for the high parametric values of the Eyring-Powell parameter.展开更多
A dynamic triaxial instrument was used to study the effects of different concentrations of sodium chloride and stress amplitudes on the dynamic properties of an expansive soil under cyclic loading.In particular,four p...A dynamic triaxial instrument was used to study the effects of different concentrations of sodium chloride and stress amplitudes on the dynamic properties of an expansive soil under cyclic loading.In particular,four parameters were considered in such a parametric investigation,namely,hysteresis curve morphology characteristic non-closure degreeεp,the ratio of the short and long axisα,the slope of the long axis k and the enclosed area S.The results show that with an increase in the sodium chloride concentration,the soil particle double electric layer becomes thinner,the distance between soil particles decreases,and the whole sample becomes denser.Theεp-N,α-N and S–N relation curves all show a decreasing trend.The ratio of plastic deformation to total deformation grows with increasing the dynamic stress amplitude,and the curves show an upwards trend.The k-N relationship curve displays an increasing trend with the concentration and a general downwards trend as the dynamic stress amplitude is made higher.This also indicates that sodium chloride solutions can improve the engineering properties of expansive soil to a certain extent.With an increase in the vibration times N,the shape of the hysteretic curve becomes narrower,and the whole soil exhibits a cyclic strain hardening.With the help of an exponential function,a model is introduced to predict the relationship between the concentration and the hysteretic curve.展开更多
文摘In this paper we propose a novel diffusion quantum Monte Carlo algo-rithm, it is a self-optimizing and self-improving procedure. The method has been em-ployed to calculate the potential energy curve of C2. The total energies for the X 1Σg+state of C2 were calculated at seven values of the bond length: 0. 106, 0. 111, 0. 124,0. 132, 0. 143, 0. 159 and 0. 185 nm; and a smooth potential energy curve was ob-tained, because when the self-optimizing technique is used, the statistical error decreas-es tremendously. The calculation results on the potential energy curve of C2 show thatthe self-optimizing diffusion quantum Monte Carlo method proposed in the present pa-per is successful.
文摘Objective To accurately extract pulmonary vessels on medical images. Methods An efficient vessel segmentation framework is presented, which includes a smoothing method and a extraction algorithm. The smoothing method is based on an improved coherence diffusion approach that integrates the second-order directional differential information. It can analyze weak edges such as narrow peak or ridge-like structures. Meanwhile, an improved extraction algorithm is proposed. It is based on a fast marching algorithm where a sorted sequence array and multi-initialization technique are applied. Results The improved coherence diffusion approach can precisely preserve important oriented patterns and remove noises on the images. Experimental results on several images show that the proposed method can effectively find the location of pulmonary vessels. Conclusion The segmentation method is accurate and fast that can be a useful tool for medical imaging applications.
文摘Potential energy curves for the lowest electronic states of LaB and LaB- have been calculated by ab initio calculations.The diffusion Monte Carlo method has been employed in combination with three different trial functions. Spectroscopic constants have also been numerically derived for the neutral molecule and compared with the only available theoretical work;^（[19]） however, predictions are provided for the corresponding constants for the anionic species which have not been reported yet. Our calculations suggest the high spin quintet state of LaB as the ground state with the triplet state higher in energy irrespective of the type of the functional used. This suggestion is in good accordance with the previous theoretical results calculated at B3LYP/LANL2DZ level of theory, whereas it contradicts with the prediction based upon B3LYP/SDD calculations in the same study. Moreover, variations of the permanent dipole moments as a function of the internuclear separations for the two electronic states of the neutral molecule have been studied and analyzed.
文摘The influence of initial placement of molecular or ion substance is investigated on the diffusion fluxes across the cell membrane. The diffusion fluxes and recovery curves are obtained by considering both the singlespot and double-spot concentrations inside the cell membrane. The results show that the additional concentration inside the membrane reduces the net fluxes at the cell interior as well as the exterior. In addition, it is found that the change in diffusion flux at the two outer walls of the membrane by the two-spot concentrations in the cell membrane is weaker than that of the single-spot concentration at the center. The variation of the influence of initial locations of the molecular concentrations inside the cell membrane on the diffusion fluxes is also discussed. This result can be applied to the diffusion process in avascular collagenous tissues.
基金supported by the National Natural Science Foundation of China(Grant No.91948303)。
文摘Remote sensing images carry crucial ground information,often involving the spatial distribution and spatiotemporal changes of surface elements.To safeguard this sensitive data,image encryption technology is essential.In this paper,a novel Fibonacci sine exponential map is designed,the hyperchaotic performance of which is particularly suitable for image encryption algorithms.An encryption algorithm tailored for handling the multi-band attributes of remote sensing images is proposed.The algorithm combines a three-dimensional synchronized scrambled diffusion operation with chaos to efficiently encrypt multiple images.Moreover,the keys are processed using an elliptic curve cryptosystem,eliminating the need for an additional channel to transmit the keys,thus enhancing security.Experimental results and algorithm analysis demonstrate that the algorithm offers strong security and high efficiency,making it suitable for remote sensing image encryption tasks.
基金Project supported by the National Natural Science Foundation of China(No.11772162)the Natural Science Foundation of Inner Mongolia Autonomous Region of China(No.2016MS0106)。
文摘Curved microchannels are often encountered in lab-on-chip systems because the effective axial channel lengths of such channels are often larger than those of straight microchannels for a given per unit chip length.In this paper,the effective diffusivity of a neutral solute in an oscillating electromagnetohydrodynamic(EMHD)flow through a curved rectangular microchannel is investigated theoretically.The flow is assumed as a creeping flow due to the extremely low Reynolds number in such microflow systems.Through the theoretical analysis,we find that the effective diffusivity primarily depends on five dimensionless parameters,i.e.,the curvature ratio of the curved channel,the Schmidt number,the tidal displacement,the angular Reynolds number,and the dimensionless electric field strength parameter.Based on the obtained results,we can precisely control the mass transfer characteristics of the EMHD flow in a curved rectangular microchannel by appropriately altering the corresponding parameter values.
基金supported by the National Natural Science Foundation of China (No. 61379072)the National Key R&D Program of China (No. 2016YFB1001501)the Fundamental Research Funds for the Central Universities (No. 2017XZZX009-03)
文摘Diffusion curves can be used to generate vector graphics images with smooth variation by solving Poisson equations. However, using the classical diffusion curve model, it is difficult to ensure that the generated diffusion image satisfies desired constraints. In this paper, we develop a model for producing a diffusion image by solving a diffusion equation with diffusion coefficients, in which color layers and coefficient layers are introduced to facilitate the generation of the diffusion image. Doing so allows us to impose various constraints on the diffusion image, such as diffusion strength, diffusion direction,diffusion points, etc., in a unified computational framework. Various examples are presented in this paper to illustrate the capabilities of our model.
文摘This study deals with the features of the mass and heat transport mechanism by adopting a modified version of Fourier and Fick’s model known as the CattaneoChristov double diffusive theory.The time-dependent magnetohydrodynamic(MHD)flow of the Eyring-Powell liquid across an oscillatory stretchable curved sheet in the presence of Fourier and Fick’s model is investigated.The acquired set of flow equations is transformed into the form of nonlinear partial differential equations(PDEs)by applying appropriate similarity variables.A convergent series solution to the developed nonlinear equations is accomplished with the help of an analytical approach,i.e.,the homotopy analysis method(HAM).The consequences of diverse parameters,including the dimensionless EyringPowell liquid parameter,the radius of curvature,the Schmidt/Prandtl numbers,the ratio of the oscillatory frequency of the sheet to its stretchable rate constant,the mass and thermal relaxation variables involved in the flow,and the heat and mass properties,are displayed through graphs and tables.It is noted from this study that the amplitude of the pressure distribution rises for the high parametric values of the Eyring-Powell parameter.
文摘A dynamic triaxial instrument was used to study the effects of different concentrations of sodium chloride and stress amplitudes on the dynamic properties of an expansive soil under cyclic loading.In particular,four parameters were considered in such a parametric investigation,namely,hysteresis curve morphology characteristic non-closure degreeεp,the ratio of the short and long axisα,the slope of the long axis k and the enclosed area S.The results show that with an increase in the sodium chloride concentration,the soil particle double electric layer becomes thinner,the distance between soil particles decreases,and the whole sample becomes denser.Theεp-N,α-N and S–N relation curves all show a decreasing trend.The ratio of plastic deformation to total deformation grows with increasing the dynamic stress amplitude,and the curves show an upwards trend.The k-N relationship curve displays an increasing trend with the concentration and a general downwards trend as the dynamic stress amplitude is made higher.This also indicates that sodium chloride solutions can improve the engineering properties of expansive soil to a certain extent.With an increase in the vibration times N,the shape of the hysteretic curve becomes narrower,and the whole soil exhibits a cyclic strain hardening.With the help of an exponential function,a model is introduced to predict the relationship between the concentration and the hysteretic curve.
