共查询到20条相似文献,搜索用时 93 毫秒
1.
2.
李宗诚 《原子与分子物理学报》2008,25(3):528-536
为建立非线性非平衡态量子力学,本文探讨建立量子开放系统边界交流均衡分析基础。一
方面,以在量子体系和它的环境之间交换的、与Wigner分布密切相关的质能流密度和质能流的广延量构成量子边界交流空间,并以边界质能流密度为核心而形成量子系统边界均衡交流分析力学;另一方面,以在量子体系和它的环境之间交换的、与Wigner分布密切相关的熵流密度和质能流的广延量构成量子边界熵流空间,并以边界熵流密度为核心而形成量子系统边界均衡交流分析力学。本文还确定量子系统的基础约束条件,对于能量结构提出效应最大化,以确立量子耗散均衡法则;初步分析对外交换基础和类完备能量流密度变化对量子系统的必要能量的影响。 相似文献
3.
本文研究了激光等离子体中由有质动力决定的准稳态密度分布,导出了局域密度标度长度、上、下密度平台长度和下平台平均密度标度长度对入射光场强和时间的依赖关系。结果表明,在达到准稳态后,随着时间的推移,上、下密度平台的长度和下平台平均密度标度长度增大,而临界密度区域的标度长度仅微小地增加,这些结果与实验及粒子模拟相一致。 相似文献
4.
5.
李宗诚 《原子与分子物理学报》2008,25(3)
为建立非线性非平衡态量子力学,本文探讨建立量子开放系统边界交流均衡分析基础.一方面,以在量子体系和它的环境之间交换的、与Wigner分布密切相关的质能流密度和质能流的广延量构成量子边界交流空间,并以边界质能流密度为核心而形成量子系统边界均衡交流分析力学;另一方面,以在量子体系和它的环境之间交换的、与Wigner分布密切相关的熵流密度和质能流的广延量构成量子边界熵流空间,并以边界熵流密度为核心而形成量子系统边界均衡交流分析力学.本文还确定量子系统的基础约束条件.对于能量结构提出效应最大化,以确立量子耗散均衡法则;初步分析对外交换基础和类完备能量流密度变化对量子系统的必要能量的影响. 相似文献
6.
在生物体系的活性系统中,杆状粒子在弹性半柔性边界中的受限行为极为常见.本文研究了二维情况下,自驱动杆状粒子受限在半柔性弹性环中的集体行为.改变系统的粒子数及噪声强度,系统显示明显的自驱吸附有序态、无序态及中间的过渡态.通过表征弹性环内部粒子的径向极性大小和空间分布的非球度性对这些状态进行了刻画.进一步对弹性环中心附近粒子密度的分析,发现环中心气态粒子分布存在一个与边界高密度区域共存的饱和平台,出现类似吸附转变的粒子分布.在过渡区间,体系内存在较大的涨落会导致弹性环出现异常形变.非对称的粒子分布对弹性环整体的迁移具有重要贡献,系统在过渡区间能获得相对较强的定向迁移. 相似文献
7.
8.
针对复杂背景下钢索图像难以准确分割的问题,提出一种基于纹理分析的钢索图像分割与边界识别方法.采用基于模糊Hough变换的纹理方向检测方法确定钢索走向,利用边缘方向密度直方图作为纹理特征,对与钢索纹理方向相应的边缘方向赋予不同权重,抑制纹理分割中背景的干扰,对钢丝绳图像进行聚类分割,采用检测平行直线的方法确定其边界,并根据算法参量对边界进行修正.在实验中,对比了边缘方向密度直方图特征与灰度共生矩阵、局部二值模式在钢索图像纹理分割中的结果与计算时间,结果表明边缘方向密度直方图特征计算速度快、受背景干扰小,分割准确率高.本文方法无须预先训练,受背景干扰小,可以准确地识别出钢索并确定其边界,能满足钢丝绳视觉检测的要求. 相似文献
9.
复杂背景下钢索图像的纹理分割与边界识别 总被引:1,自引:0,他引:1
针对复杂背景下钢索图像难以准确分割的问题,提出一种基于纹理分析的钢索图像分割与边界识别方法.采用基于模糊Hough变换的纹理方向检测方法确定钢索走向,利用边缘方向密度直方图作为纹理特征,对与钢索纹理方向相应的边缘方向赋予不同权重,抑制纹理分割中背景的干扰,对钢丝绳图像进行聚类分割,采用检测平行直线的方法确定其边界,并根据算法参量对边界进行修正.在实验中,对比了边缘方向密度直方图特征与灰度共生矩阵、局部二值模式在钢索图像纹理分割中的结果与计算时间,结果表明边缘方向密度直方图特征计算速度快、受背景干扰小,分割准确率高.本文方法无须预先训练,受背景干扰小,可以准确地识别出钢索并确定其边界,能满足钢丝绳视觉检测的要求. 相似文献
10.
托卡马克等离子体的热平衡特性与脱栏现象 总被引:1,自引:1,他引:0
本文利用欧姆加热条件下简化的能量平衡方程研究了热传导与杂质辐射的综合效应。首先指出边缘辐射带的建立与随半径增大而增大的K=nx模型紧密相关(x为电子热传导系数,n为等离子体密度),然后利用删削层中能量平衡关系确定边界温度,自洽地求解了能量平衡方程,得出的脱栏等离子体形成条件能较好地解释有关实验观察到的多种现象。 相似文献
11.
12.
13.
Tokamak plasma density evolution is generally modeled by a
diffusion--convection equation in cylindrical geometry. By using a
semi-analytical approach, we solve such an equation for a given
diffusion coefficient and inward convection velocity as an arbitrary
function of the radial position. Through variable separation, a
Sturm--Liouville-type eigenvalue problem is solved, thereby
constructing a complete set of orthogonal eigenfunctions. Based on
the decomposition of the solution, the initial function, and the
source function in these eigenfunctions, several problems of
practical interest about the density evolution are analyzed. They
include the density evolution, with boundary density not being zero;
the density profile with internal transport barrier; the damping profile
during particle source being shut-down. Results are found to be
qualitatively consistent with the tokamak experiments. 相似文献
14.
T. Salditt C. Li A. Spaar U. Mennicke 《The European physical journal. E, Soft matter》2002,7(2):105-116
We have investigated the structure of solid-supported, multilamellar membranes by X-ray reflectivity. The density profile
is obtained by fitting the full q-range to a model using the bilayer Fourier coefficients as fitting parameters. The effect of hydration and the substrate
boundary condition are discussed in view of the well-known Landau-Peierls effect and its implications for structure determination.
The resulting bilayer density profile agrees remarkably well with previously published data of a molecular dynamics (MD) simulation
for 1,2-oleoyl-palmitoyl-sn-glycero-3-phosphocholine (OPPC).
Received 1 October 2001 and Received in final form 21 December 2001 相似文献
15.
A theory is presented which allows us to accurately calculate the density profile of monovalent and multivalent counterions in suspensions of polarizable colloids or nanoparticles. In the case of monovalent ions, we derive a weak-coupling theory that explicitly accounts for the ion-image interaction, leading to a modified Poisson-Boltzmann equation. For suspensions with multivalent counterions, a strong-coupling theory is used to calculate the density profile near the colloidal surface and a Poisson-Boltzmann equation with a renormalized boundary condition to account for the counterion distribution in the far field. All the results are compared with the Monte?Carlo simulations, showing an excellent agreement between the theory and the simulations. 相似文献
16.
纳米孔隙内气体流动的理论预测对气体微流控器件的设计和制造具有重要的理论指导作用,文章采用分子动力学方法研究了氮气、氧气和二氧化碳混合气体在平行壁纳米孔隙内的剪切流动特性和边界滑移特性.研究结果表明:随着加入二氧化碳比例的不断增加,混合气体滑移速度不断增大,并且当二氧化碳的比例低于20%时,混合气体流动速度沿孔隙宽度方向呈线性分布;而当比例达到40%后,其速度轮廓将呈现非线性趋势.当二氧化碳所占比例为20%时,随着孔隙宽度的增加,混合气体的整体边界滑移随之减小.探究了混合气体密度和气-固耦合强度对混合气体流动及边界滑移的影响机理.发现随着混合气体密度的减小,气流边界滑移增大;随着气-固界面耦合强度的增强,边界气体分子易被吸附而出现黏滑运动,气体分子在边界处的积聚现象增强,剪切应变率增大,边界滑移减小. 相似文献
17.
V. V. Yankov 《JETP Letters》2003,77(9):490-492
Theory of turbulent equipartition and experiment indicate that density, pressure, and temperature profiles follow the poloidal magnetic field profile. Therefore, it is suggested to change the magnetic geometry between core and boundary by toroidal conductors and/or plasma current. As a result, density and temperature gradients will become steeper, and stored energy will be higher with low boundary plasma parameters. The suggested new mode of confinement may substantially simplify achieving of ignition. 相似文献
18.
赵晴初 《核聚变与等离子体物理》1991,11(3):177-180
在Tokamak等离子体实验结果分析中实际的平衡磁面是极需要的。本文试探从电磁测量信号推得平衡磁面。 一、自由边界平衡程序 借助于自由边界平衡程序计算中等托卡马克装置HT-6M的平衡量。从MHD平衡方程出发, 相似文献
19.
A general condition for a Markov process with finite states is given for the convergence of the normalized hitting time of a rare event to a mean one exponential law. It is then applied to the boundary driven symmetric simple exclusion process for an open set of density profiles which does not contain the stationary density profile. 相似文献
20.
M. V. Kuzelev N. G. Orlikovskaya 《Journal of Experimental and Theoretical Physics》2016,123(6):1090-1098
A theory of surface waves in a magnetoactive plasma with smooth boundaries has been developed. A dispersion equation for surface waves has been derived for a linear law of density change at the plasma boundary. The frequencies of surface waves and their collisionless damping rates have been determined. A generalization to an arbitrary density profile at the plasma boundary is given. The collisions have been taken into account, and the application of the Landau rule in the theory of surface wave damping in a spatially inhomogeneous magnetoactive collisional plasma has been clarified. 相似文献