The vacuum energy density of free scalar quantum field in a Rindler distributional space-time with distributional Levi-Cività connection is considered. It has been widely believed that, except in very extreme sit...The vacuum energy density of free scalar quantum field in a Rindler distributional space-time with distributional Levi-Cività connection is considered. It has been widely believed that, except in very extreme situations, the influence of acceleration on quantum fields should amount to just small, sub-dominant contributions. Here we argue that this belief is wrong by showing that in a Rindler distributional background space-time with distributional Levi-Cività connection the vacuum energy of free quantum fields is forced, by the very same background distributional space-time such a Rindler distributional background space-time, to become dominant over any classical energy density component. This semiclassical gravity effect finds its roots in the singular behavior of quantum fields on a Rindler distributional space-times with distributional Levi-Cività connection. In particular we obtain that the vacuum fluctuations have a singular behavior at a Rindler horizon . Therefore sufficiently strongly accelerated observer burns up near the Rindler horizon. Thus Polchinski’s account doesn’t violate the Einstein equivalence principle.展开更多
Ansotropic diffusion has good effect on reducing noise and preserving edge, but it may lose some details due to the blocky effect and can not suppress speckle effectively. The Laplacian factor is used to process the o...Ansotropic diffusion has good effect on reducing noise and preserving edge, but it may lose some details due to the blocky effect and can not suppress speckle effectively. The Laplacian factor is used to process the observed image which is considered as a piecewise planar image, so the Fourth Order Anisotropic Diffusion (FOAD) can avoid the blocky effect. The edge is preserved and enhanced by the Line Edge Detector (LED) based on stick technique and hypothesis test optimizing method. An approach called the Fourth Order Anisotropic Diffusion and Edge Enhancing (FOADEE), where the LED is combined with the FOAD, is presented. For quantitative evaluation and comparison with the LED, the FOAD and the FOADEE, two parameters as measure of the noise suppression and edge preservation are introduced. It is proved that the novel method can not only suppress speckle prominently but also preserve even enhance edge and useful details effectively by applying it to the phantoms and tissue images.展开更多
A clear mathematical theory of time remains one of the most difficult challenges of science, which seems highly intriguing. In this work, we assume that time is the main independent attribute of nature and therefore m...A clear mathematical theory of time remains one of the most difficult challenges of science, which seems highly intriguing. In this work, we assume that time is the main independent attribute of nature and therefore may serve as the foundation of a comprehensive field theory. Furthermore, we assume that division algebras with the Euclidean norm are essential mathematical tools of time and the physical world in general. We use a four-dimensional normed division algebra of quaternions to describe time mathematically, as originally envisioned by Hamilton. We systematically define basic quaternion concepts related to time, such as the quaternion time interval, scalar measured time, the arrow of time, vector velocity, and quaternion frequency. We apply quaternion time concepts to the optical Doppler effect and demonstrate that our approach predicts known experimental results. Furthermore, we show that the quaternion solution of the Doppler effect enhances the relativity theory by resolving the notorious twin paradox. We identify quaternion frequency with the traditional concept of energy. We assume that quaternion energy, which is generally dependent on time and external interactions, can be used to describe dynamic properties of matter. In conclusion, we suggest that a state of matter can be represented by the eight-dimensional octonion configuration space, consisting of a quaternion time interval and a time dependent quaternion frequency. Therefore, it appears that the application of normed division algebras for the study of time and nature is highly logical, credible, and compelling.展开更多
After the three-dimensional self-affine fractal random surface simulation, we use the optical scattering theory to calculate the deep Fresnel region speckle(DFRS) under consideration of the more strict shadowing effec...After the three-dimensional self-affine fractal random surface simulation, we use the optical scattering theory to calculate the deep Fresnel region speckle(DFRS) under consideration of the more strict shadowing effect. The evolution of DFRS with the scattering distance and the intensity probability distribution are studied. It is found that the morphology of the scatterer has an antisymmetric relationship with the intensity distribution of DFRS, and the effect of micro-lenses on the scattering surface causes the intensity probability distribution of DFRS to deviate from the Gaussian speckle in the high light intensity area.展开更多
文摘The vacuum energy density of free scalar quantum field in a Rindler distributional space-time with distributional Levi-Cività connection is considered. It has been widely believed that, except in very extreme situations, the influence of acceleration on quantum fields should amount to just small, sub-dominant contributions. Here we argue that this belief is wrong by showing that in a Rindler distributional background space-time with distributional Levi-Cività connection the vacuum energy of free quantum fields is forced, by the very same background distributional space-time such a Rindler distributional background space-time, to become dominant over any classical energy density component. This semiclassical gravity effect finds its roots in the singular behavior of quantum fields on a Rindler distributional space-times with distributional Levi-Cività connection. In particular we obtain that the vacuum fluctuations have a singular behavior at a Rindler horizon . Therefore sufficiently strongly accelerated observer burns up near the Rindler horizon. Thus Polchinski’s account doesn’t violate the Einstein equivalence principle.
基金Supported by the Youth Science Foundation of South China University of Technology (No.321E5040950).
文摘Ansotropic diffusion has good effect on reducing noise and preserving edge, but it may lose some details due to the blocky effect and can not suppress speckle effectively. The Laplacian factor is used to process the observed image which is considered as a piecewise planar image, so the Fourth Order Anisotropic Diffusion (FOAD) can avoid the blocky effect. The edge is preserved and enhanced by the Line Edge Detector (LED) based on stick technique and hypothesis test optimizing method. An approach called the Fourth Order Anisotropic Diffusion and Edge Enhancing (FOADEE), where the LED is combined with the FOAD, is presented. For quantitative evaluation and comparison with the LED, the FOAD and the FOADEE, two parameters as measure of the noise suppression and edge preservation are introduced. It is proved that the novel method can not only suppress speckle prominently but also preserve even enhance edge and useful details effectively by applying it to the phantoms and tissue images.
文摘A clear mathematical theory of time remains one of the most difficult challenges of science, which seems highly intriguing. In this work, we assume that time is the main independent attribute of nature and therefore may serve as the foundation of a comprehensive field theory. Furthermore, we assume that division algebras with the Euclidean norm are essential mathematical tools of time and the physical world in general. We use a four-dimensional normed division algebra of quaternions to describe time mathematically, as originally envisioned by Hamilton. We systematically define basic quaternion concepts related to time, such as the quaternion time interval, scalar measured time, the arrow of time, vector velocity, and quaternion frequency. We apply quaternion time concepts to the optical Doppler effect and demonstrate that our approach predicts known experimental results. Furthermore, we show that the quaternion solution of the Doppler effect enhances the relativity theory by resolving the notorious twin paradox. We identify quaternion frequency with the traditional concept of energy. We assume that quaternion energy, which is generally dependent on time and external interactions, can be used to describe dynamic properties of matter. In conclusion, we suggest that a state of matter can be represented by the eight-dimensional octonion configuration space, consisting of a quaternion time interval and a time dependent quaternion frequency. Therefore, it appears that the application of normed division algebras for the study of time and nature is highly logical, credible, and compelling.
文摘After the three-dimensional self-affine fractal random surface simulation, we use the optical scattering theory to calculate the deep Fresnel region speckle(DFRS) under consideration of the more strict shadowing effect. The evolution of DFRS with the scattering distance and the intensity probability distribution are studied. It is found that the morphology of the scatterer has an antisymmetric relationship with the intensity distribution of DFRS, and the effect of micro-lenses on the scattering surface causes the intensity probability distribution of DFRS to deviate from the Gaussian speckle in the high light intensity area.
文摘光束在大气湍流中传输时,大气湍流效应对光束进行强度和相位的随机调制,最终在远场处形成散斑。以部分相干高斯-谢尔模型(Gaussian-Schell Model,GSM)光束为研究对象,根据广义的HuygensFresnel原理、修正Von Karman谱模型,推导了GSM光束在大气湍流中传输时接收端光束的有效半径和平均散斑半径的表达式。利用数值计算对比分析光源相关参数和大气湍流对光束有效半径和平均散斑半径的影响。研究表明:光束的初始束腰半径越大、相干长度越小以及波长越小时,接收端光束的有效半径和平均散斑半径受湍流的影响越小;大气折射率结构常数越大,光束扩展越严重,此时平均散斑半径越小;光束有效半径和平均散斑半径随湍流外尺度增大几乎无变化,随湍流内尺度的增大而减小。所得出的结论对无线激光通信系统中光束的捕获、对准与跟踪(Acquisition,Pointing and Tracking,APT)系统的设计提供一个重要的参考价值。
