一般加速带电带磁的动态黑洞中标量场的熵

在一般加速带电带磁的动态黑洞中,化简Klein-Gordon场方程,利用乌龟坐标变换,得到在视界面附近的辐射温度.用薄膜brick-wall模型,选择适当的截断因子和薄膜厚度,得到在视界面附近薄膜上的熵,结果表明黑洞熵与视界面积成正比. 关键词： 黑洞 Hawking温度 薄膜brick-wall模型 熵     

小波双线性插值搜索算法及其在光学遥感图像中的应用

详细分析了在小波双线性插值中高频外推阈值门限与峰值信噪比的变化关系,提出了基于峰值信噪比最大的小波双线性插值搜索算法。提出的算法能够自动搜索到峰值信噪比最大的高频外推最佳阈值门限,实现了在不破坏光学遥感图像原始信息的情况下,提高了图像的空间分辨率,有利于对图像的细节信息进行观察分析。实验结果表明:该算法能够得到比双线性插值和全小波插值更高的峰值信噪比、熵值和更好的图像细节效果,是一种适合提高光学遥感图像分辨率的有效算法。     

图像局部熵用于小目标检测研究

分析了局部熵用于小目标检测时造成目标范围扩散等问题的原因,并提出了熵增长方法.该方法用于点目标检测可避免发生目标范围扩散现象.由于边缘纹理和点目标在熵增长处理过程中表现出截然相反的属性,故可避免边缘纹理对于小目标检测产生的严重干扰.该方法也可用于不受噪声干扰的边缘检测.针对相同信噪比目标在不同背景亮度中具有不同熵值和增长量的问题,提出用方差增长替代熵增长,使相同信噪比目标在不同背景亮度中表现出相同的增长量值,降低了后续目标分割的难度.试验表明,熵增长方法和方差增长方法能够有效检测1或2像素大小的点目标,并不受背景中边缘纹理的干扰.对算法的复杂度进行了分析,并提出采用双通道并行流水线方式实现工程化的设计思路.     

运动纠缠双原子与薛定谔猫态光场相互作用系统的场熵演化

利用全量子理论,研究了运动纠缠双原子与薛定谔猫态光场相互作用系统的场熵演化特性,讨论了光场强弱、相干态间的相位角、原子的运动和场模结构参数对系统场熵的影响.结果表明：原子运动导致场熵演化具有周期性;当场强较弱时,奇相干态光场与运动原子的纠缠度最大,而偶相干态光场与运动原子的纠缠度最小, Yurke-Stoler相干态光场与运动原子的纠缠度值介于中间;当场强足够大时,分别处于Yurke-Stoler相干态,奇相干态和偶相干态的光场与运动原子的纠缠度相等,场熵演化特性相同;随着原子运动速度的增大或场模结构参数的增大,场熵的演化周期缩短,并且场与原子的纠缠度逐渐减弱.     

Kerr解的新形式及其隧穿辐射

Parikh最近将黑洞辐射视为半经典的隧穿过程,在考虑了自引力相互作用后,得出静态球对称Schwarzschild和Reissner-Nordstrm黑洞的辐射谱不是纯热谱.采用Doran给出的Kerr黑洞解的新形式,将Parikh的工作推广到Kerr黑洞,研究转动黑洞的隧穿辐射,得到了修正的辐射谱,它与黑洞的Bekenstein-Hawking熵变有关,不是纯热谱,但满足量子力学中的幺正性原理. 关键词： Kerr黑洞 隧穿辐射 自引力修正 Bekenstein-Hawking熵     

Analytic solutions for degenerate Raman-coupled model

The Raman-coupled interaction between an atom and a single mode of a cavity field is studied. For the cases in which a light field is initially in a coherent state and in a thermal state separately, we have derived the analytic expressions for the time evolutions of atomic population difference W, modulus B of the Bloch vector, and entropy E. We find that the time evolutions of these quantities are periodic with a period of π. The maxima of W and B appear at the scaled interaction time points τ- = kπ（k = 0, 1, 2,...）. At these time points, E = 0, which shows that the atom and the field are not entangled. Between these time points, E ≠ 0, which means that the atom and the field are entangled. When the field is initially in a coherent state, near the maxima, the envelope of W is a Gaussian function with a variance of 1/（4n^-）（n^- is the mean number of photons）. Under the envelope, W oscillates at a frequency of n^-/π. When the field is initially in a thermal state, near the maxima, W is a Lorentz function with a width of 1/n^-.     

双模SU（2）相干场与∧型三能级原子耦合系统中场熵的演化

研究了双模SU（2）相干场与∧型三能级原子相互作用系统中场熵的演化特性。讨论了两场模与原子的耦合系数相对大小、单模场中光子数的最大可能值Ⅳ和描述两个场模光子平均数之比参数f的变化对场熵演化的影响。数值计算结果表明：两场模与原子的耦合强度近似相等时,场熵随时问作等幅周期性振荡;当两场模与原子的耦合系数相差较大时场熵演化出现崩塌和恢复现象,崩塌持续时间随两场模与原子的耦合系数之比l和两个场模光子平均数之比f增大而缩短,随单模场中光子数的最大可能值N增大而增大。     

A Simple Model for Simulation of Armature Expanding Process

We propose a scheme to simulate the dynamic process of the armature expansion of explosive magnetic flux compression generators. Values of the deflective angle and the velocity of expanding the innermost radius of copper cylinder (or armature) caused by explosive detonation are calculated, which are in good agreement with     

Universal Scaling Law for Atomic Diffusion and Viscosity in Liquid Metals

The recently proposed scaling law relating the diffusion coefficient and the excess entropy of liquid [Samanta A et al. 2004 Phys. Reu. Lett. 92 145901; Dzugutov M 1996 Nature 381 137], and a quasi-universal relationship between the transport coefficients and excess entropy of dense fluids [Rosenfeld Y 1977 Phys. Rev. A 15 2545],are tested for diverse liquid metals using molecular dynamics simulations. Interatomic potentials derived from the glue potential and second-moment approximation of tight-binding scheme are used to study liquid metals.Our simulation results give sound support to the above-mentioned universal scaling laws. Following Dzugutov,we have also reached a new universal scaling relationship between the viscosity coefficient and excess entropy.The simulation results suggest that the reduced transport coefficients can be expressed approximately in terms of the corresponding packing density.     

Quantum statistical entropy for Kerr－de Sitter black hole

Improving the membrane model by which the entropy of the black hole is studied, we study the entropy of the black hole in the non-thermal equilibrium state. To give the problem stated here widespread meaning, we discuss the (n 2)-dimensional de Sitter spacetime. Through discussion, we obtain that the black hole‘s entropy which contains two horizons (a black hole‘s horizon and a cosmological horizon) in the non-thermal equilibrium state comprises the entropy corresponding to the black hole‘s horizon and the entropy corresponding to the cosmological horizon. Furthermore, the entropy of the black hole is a natural property of the black hole. The entropy is irrelevant to the radiation field out of the horizon. This deepens the understanding of the relationship between black hole‘s entropy and horizon‘s area. A way to study the bosonic and fermionic entropy of the black hole in high non-thermal equilibrium spacetime is given.