态|Ψ(3)〉q中广义磁场的不等幂次高次振幅压缩

利用多模压缩态理论,研究了一种新型的三态叠加多模叠加态光场|Ψ⁽³⁾〉_q中广义磁场分量(即第一正交相位分量)的不等幂次高次振幅压缩特性.结果表明:态|Ψ⁽³⁾〉_q是一种典型的三态叠加多模非经典光场,其广义磁场分量在一定条件下可呈现出周期性变化的、偶数次的不等幂次高次振幅压缩效应.     

态|ψ3(3)〉q中广义磁场分量的N次方Y压缩效应

构造了由多模复共轭相干态|{Z_j^*}〉_q、多模复共轭虚相干态|{iZ_j^*}〉_q和多模真空态|{Q_j} 〉_q这三态的线性叠加所组成的第Ⅲ类三态叠加多模叠加态光场|ψ₃⁽³⁾〉_q.利用多模压缩态理论研究了态|ψ₃⁽³⁾〉_q中广义磁场分量的任意偶数次广义非线性等幂次N次方Y压缩特性.结果发现:在压缩次数N取偶数,只要各模的初始相位φ_j(j=1,2,3,…,…,q),态间的初始相位差(θ_i-θ₂)(i=1,3)和各单模相干态光场平均光子数R_j²之和 分别满足各自的取值条件,态|ψ₃⁽³⁾〉_q的广义磁场分量(即第一正交相位分量)就可呈现出周期性变化的、任意偶数次的广义非线性等幂次N次方Y压缩效应.     

太阳中微子失踪案和中微子振荡

 (续前)五、“中微子振荡”是物理学家的法宝按照粒子物理的标准模型,中微子质量为零,它们以光速运动。存在着3种不同类型(即3种“味”)的中微子:电子型中微子(记为νｅ),μ-中微子(记为νμ)和τ-中微子(记为ντ),它们之间彼此不相关,分别只同电子、μ轻子和τ轻子密切相关。不过,早在戴维斯等人公布首批氯探测器的探测结果的1968年,庞托科沃就提出了这3种“味”的中微子很有可能互相来回地转化,称为“中微子振荡”。在太阳内部的热核燃烧过程中产生的中微子都是νｅ。但它们在从太阳到地球的漫长行进过程中,νｅ不断地转化为νμ和ντ。     

Measurement of Change of ^7Be Decay Rate in Be and Au

We have measured the possible change of the decay rate of ^7Be implanted into hosts of natural beryllium and natural gold. No difference between the ^7 Be decay rates in the two hosts is observed within the experimental precision of 0.12%. This result implies that change of the decay rate of ^7Be implanted in different materials cannot be simply expected from the electron affinity difference consideration lonely and the lattice structure of the host materials should be taken into account.     

硼中子俘获治疗的蒙特卡罗方法模拟

用通用蒙特卡罗程序MCNP模拟了粒子在人脑中的输运过程. 吸收剂量率主要来自以下四个反应:¹⁰B(n,α)⁷Li,¹⁴N(n,p)¹⁴C,¹H(n,γ)²D,快中子弹性散射反应.对肿瘤区的贡献主要来自硼中子吸收反应.结果表明,超热中子比热中子适合于深肿瘤的治疗,而热中子对浅肿瘤的治疗有优越性,比如皮肤癌.同确定论方法的结果相比,蒙特卡罗方法不失为一种模拟中子俘获治疗的好工具.     

Corkscrew振荡引起的发射度增长

 用解析方法来确定由二种因素引起的Corkscrew振荡所造成的归一发射度增长的表达式。这二种因素是电子束的非理想注入以及聚焦磁场相对于系统轴的随机偏斜。     

梯度磁场作用下光纤中磁流体光透射特性研究的建模与分析

对光纤中磁流体在梯度磁场作用下的光透射特性进行了研究,提出光纤中磁流体的光透射率变化主要来源于梯度磁场引起的磁流体密度分布变化。根据郎之万函数和流体理论,推导了光纤中磁流体在梯度磁场作用下的密度分布,并根据Beer-Lambert定律,得到磁流体光功率透射衰减和纳米粒子局部密度的关系,从而建立光纤中磁流体在梯度磁场作用下光透射特性的理论模型。进而对光纤中磁流体在不同梯度磁场作用下的光透射功率进行数值分析,得到不同磁场强度和磁场梯度下光纤中磁流体透射功率的变化规律。最后将数值分析的结果和实验数据进行对比,验证了模型的合理性, 同时也验证了梯度磁场作用下磁流体光透射功率的变化主要来源于磁流体密度分布变化的推论。     

亥姆霍兹线圈磁场的均匀性分析

引入磁场均匀度的概念，对亥姆霍兹线圈磁场的均匀性进行了定量分析，并通过计算机模拟，得出了同一精度下，形成亥姆霍兹线圈均匀磁场的最佳条件．     

Spin gapless armchair graphene nanoribbons under magnetic field and uniaxial strain

Using Green＇s function method, we investigate the spin transport properties of armchair graphene nanoribbons （AG- NRs） under magnetic field and uniaxial strain. Our results show that it is very difficult to transform narrow AGNRs directly from semiconductor to spin gapless semiconductors （SGS） by applying magnetic fields. However, as a uniaxial strain is exerted on the nanoribbons, the AGNRs can transform to SGS by a small magnetic field. The combination mode be- tween magnetic field and uniaxial strain displays a nonmonotonic arch-pattern relationship. In addition, we find that the combination mode is associated with the widths of nanoribbons, which exhibits group behaviors.     

Simultaneous effects of magnetic field and space porosity on compressible Maxwell fluid transport induced by a surface acoustic wave in a microchannel

Peristaltic motion induced by a surface acoustic wave of a viscous, compressible and electrically conducting Maxwell fluid in a confined parallel-plane microchannel through a porous medium is investigated in the presence of a constant magnetic field. The slip velocity is considered and the problem is discussed only for the free pumping case. A perturbation technique is employed to analyze the problem in terms of a small amplitude ratio. The phenomenon of a “backward flow” is found to exist in the center and at the boundaries of the channel. In the second order approximation, the net axial velocity is calculated for various values of the fluid parameters. Finally, the effects of the parameters of interest on the mean axial velocity, the reversal flow, and the perturbation function are discussed and shown graphically. We find that in the non-Newtonian regime, there is a possibility of a fluid flow in the direction opposite to the propagation of the traveling wave. This work is the most general model of peristalsis created to date with wide-ranging applications in biological, geophysical and industrial fluid dynamics.