多次散射辐射传输计算中的相函数处理

在实际大气中,分子和粒子不仅遭受单次散射,还遭受多次散射。本文首先计算了多次散射在总散射量中的贡献。结果表明当光学厚度大于0.1时,多次散射在总散射量中的贡献将超过10%,因此必须考虑多次散射的作用。在多次散射辐射传输计算时,一般需把散射相函数展开为勒让德(Legendre)函数的多项式。有些介质如云或气溶胶粒子,散射相函数前向非常尖锐。展开的Legendre多项式需数百项甚至上千项才能收敛,而计算时间与展开项数的3次方成正比。本文介绍了在辐射传输计算时对尖锐相函数的δ-M和δ-fit处理方法,比较了两种方法的计算结果。当计算用的流数相同时,δ-fit方法的计算结果比δ-M方法的计算结果要精确得多;当计算结果精确度相同时,δ-fit方法的流数比δ-M方法的流数少得多,运算速度也快很多。δ-fit方法是目前处理散射相函数的理想方法,可以大大提高计算的精度以及缩减运算时间。     

二维δ函数及其在静电学中的应用

简介二维δ函数的定义及有关公式，并举例说明二维δ函数在静电学中的应用，为电动力学的教学提供一类解二维问题的简单方法．     

δ函数的定义及其性质

对δ函数的传统定义及由此引起的奇性展开讨论,说明了在经典意义下δ函数可以被看成是弱收敛函数序列的弱极限以及阶跃函数Heaviside函数的导数;最后,借用泛函分析中广义函数的概念给出了δ函数的严格数学定义,并就其性质进行了讨论．     

δ函数导数在电磁学中的一些应用

本文说明理想电偶极子、电四极子的电荷分布可分别用δ函数的一阶、二阶导数来表示．在此基础上，运用δ函数导数的计算公式。可以直观、简便地得出理想电多极子的静电势和辐射场标势的表达式     

狄拉克δ-函数及有关应用

狄拉克δ-函数实际上是离散情况下的Kroneckerδ-函数的连续化,它在数学和物理中都有重要的应用.基于广义函数概念引入狄拉克δ-函数的精确定义,证实狄拉克δ-函数不是通常Lebesgue局部可积意义下的普通函数;文中分别以单位矩形脉冲函数、高斯函数、钟形函数和Sinc函数的序列在弱极限意义下来逼近狄拉克δ-函数.另外,验证了狄拉克δ-函数可以作为Heaviside函数的广义导数,以及其高价广义导数,并给出狄拉克δ-函数的卷积性质、伸缩性质、复合变换性质、正交性和狄拉克梳函数,最后引入了狄拉克δ-函数与广义傅里叶变换的关系,以及其在泊松方程Dirichlet边值问题求解中的应用.     

单晶GdBa2Cu3O6＋δ顺磁性和超导性的研究

掺杂有顺磁性稀土元素离子的高温超导体的磁滞回线因包含有顺磁的贡献而变宽，使根据Bean模型得到的临界电流密度偏离了其真实的值．本文对描述其中顺磁性磁化强度贡献的扩展Brillouin函数进行了修正，并将该种描述方法应用于单晶GdBa2Cu3O6＋δ样品．外场低于临界场HC1时，顺磁性对总的磁化强度没有贡献；外场高于HC1的磁场下，磁场增加和磁场降低时顺磁性的磁化贡献并不相等．由此验证了在GdBa2Cu3O6＋δ的晶体结构中，超导电流沿Cu-O面流动，对位于两层Cu-O面间的顺磁性离子产生屏蔽作用．GdBa2Cu3O6＋δ中超导性和顺磁性相互独立共存，超导性通过电流的屏蔽作用间接的影响了顺磁性的贡献．     

带δ函数势无限深势阱中的能谱研究

当无限深势阱中加入δ函数势后,受影响最大的是基态,当δ函数势由排斥变为吸引时,基态能量由正变负,而其他能级保持为正.     

改进了的价连接性指数及其应用实例：δi和δ^v在结构／性质相关 …

对价连接性值δ＾ｖ实行了改造，重新定义了价连性值δ＾－ｉ，认为分子中某一原子的特征数值δ与某原子的价电子数，成键电子数，价电子层的最高主要量子数有关，对于碳氢体系，顶点的连接度，δｖ，δｉ具有相同的数值，对于含杂原子体系，δ具有更大的适用范围，给出两个例子论证之，同时，δ，δｉ具有相似的定义形式，所以由δｖ构成的各级价连接性指数＾ｍＸ＾ｖｉ的方法可以完全移植过程，由δ构成的拓扑指数记为＾ｍＸｉ作为     

狄拉克δ函数

从狄拉克δ函数8(x)的定义出发,说明其在x=0处无定义,8(x)具有x倒数的量纲,并且具有x算符本征函数的物理含意,澄清了量子力学教材中的一些模糊认识.     

δ函数SN方法求解含各向异性散射输运方程的本征值问题

将角通量分解成一个δ函数和一个低阶函数,分别采用解析方法和求积组来计算源项.利用δ函数S_N方法,计算了平几何条件下含各向异性散射单速输运方程的临界问题.分析和数值结果表明,采用数量较少的离散方向,能够达到较高计算精度.     

FLAPW方法研究δ-钚(001)面的性质

采用 FLAPW(全势线性缀加平面波)方法,在广义梯度近似(GGA)、反铁磁(AFM)下研究了δ-钚(001)面的性质.计算得到的表面能系数和功函数分别为0.08 eV/(A)2和3.15 eV,接近其近邻元素α-铀的实验值(0.094 eV/(A)2和3.4～3.9 eV).与体相原子相比,表层原子由于近邻原子数目的减少,5f-5f和5f-6d轨道波函数重叠、杂化几率降低,5f电子定域化特性增强,局部磁矩增大.表层原子向内收缩2.70%,然而,由于表面弛豫能很小,δ-钚(001)面相当稳定.     

First-order reversal curves of magnetic recording tapes

The interaction and its variation between magnetic grains in two kinds of magnetic recording tapes are investigated by first-order reversal curves (FORC) and the $\delta M$ method. The composition and microstructure of the samples are characterised by x-ray diffraction and scanning electron microscope. The FORC diagram can provide more accurate information of the interaction and its variation, but the $\delta M$ curves cannot. The positive interaction field and the large variation of the interaction field have opposite effects on the $\delta M$ curve.     

δ掺杂对Si衬底GaN蓝光LED外延膜性能的影响研究

用X射线衍射方法通过不同晶面的ω扫描测试,分析了Si衬底GaN蓝光LED外延膜中n-型层δ掺杂Si处理对外延膜结晶性能的影响。报道了Si衬底GaN外延膜系列晶面的半峰全宽(FWHM)值。通过使用晶格旋转(Lattice-rotation)模型拟合,计算出样品的螺位错密度和刃位错密度。结果表明,δ掺杂Si处理后生长出的样品螺位错密度增大、刃位错密度减小,总位错密度有所减小。通过对未经δ掺杂处理和δ掺杂处理的GaN外延膜相应ω-2θ扫描半峰全宽值的比较,发现δ掺杂Si处理后生长出的样品非均匀应变较大;相应样品的LED电致发光光谱I、-V特性曲线显示δ掺杂后样品性能变好。     

波前编码系统的点扩散函数稳相法分析

本文利用稳相法从本质上分析了三次相位波前编码系统的点扩散函数特性.通过分析三次相位板任意位置掩膜带和点扩散函数的关系,指出点扩散函数和稳相点的关系:两个稳相点引起点扩散函数的振荡,一个稳相点则只会造成点扩散函数的平稳变化.相位掩膜带或相位掩膜对的对称结构是同一区域内存在两个稳相点的必要条件,对称结构的不同位置对应于点扩散函数的不同部分.这种对应关系同时解释了对焦点扩散函数只存在振荡,而离焦点扩散函数却还存在平缓变化区域的本质原因,这是由离焦时光学对称轴和几何对称轴不重合引起的.本文建立了点扩散函数和对称相位掩膜对之间的对应关系,可以有效地指导相位掩膜的加工和检验.     

半结晶聚酯(PET)的二相共存结构的表征

采用X射线衍射对称反射法,对半结晶聚酯PET₂试样收集粉末X射线衍射全图(XDWP)数据,用Rietveld方法和Fourier过滤技术,对XDWP拟合并分离成结晶衍射峰之和CR₂和非晶散射峰之和AM₂两部分,与此同时获得PET₂试样的结晶相CR₂的三斜晶系晶胞参数:a=0.445,b=0.592,c=1.072nm,α=99.6,β=116.9,γ=111.9(°),结晶密度d_{c关键词： 聚对苯二甲酸乙二醇酯 二相共存结构 径向分布函数 Rietveld方法 Fourier过滤技术}     

On phases and length of curves in a cyclic quantum evolution

The concept of a curve traced by a state vector in the Hilbert space is introduced into the general context of quantum evolutions and its length defined. Three important curves are identified and their relation to the dynamical phase, the geometric phase and the total phase are studied. These phases are reformulated in terms of the dynamical curve, the geometric curve and the natural curve. For any arbitrary cyclic evolution of a quantum system, it is shown that the dynamical phase, the geometric phase and their sums and/or differences can be expressed as the integral of the contracted length of some suitably-defined curves. With this, the phases of the quantum mechanical wave function attain new meaning. Also, new inequalities concerning the phases are presented.     

Qualitative-(semi)quantitative data acquisition of artemisinin and its metabolites in rat plasma using an LTQ/Orbitrap mass spectrometer

Artemisinin (QHS) is one of the first-line antimalarials, and autoinduction of CYP-mediated metabolism can result in its reduced exposure. To better understand the autoinduction of QHS, we evaluated the pharmacokinetics of QHS and its phase I metabolites in rats using an liquid chromatography-high resolution mass spectrometry (LC-HRMS) method. The LC separation was improved, allowing the separation of QHS and its metabolites from their diastereomers, and seven metabolites of QHS with relatively high exposure were identified in rat plasma, including deoxyartemisinin (DQHS), three monoyhydroxylated plus deoxyl metabolites (M1-M3) and three monohydroxylated metabolites (M4-M6). For detection, a high-resolution LTQ/Orbitrap mass spectrometer with an electrospray ionization (ESI) inlet in the positive ion mode was used. High-resolution extracted ion chromatograms for each analyte were obtained by processing the full-scan MS dataset with 10 ppm mass tolerance. The plasma samples were pretreated by protein precipitation with acetonitrile. The standard curve was linear (r(2) > 0.99) over the QHS and DQHS concentration range of 5.0-200.0 ng/ml in 50 μl of plasma, which offered sufficient sensitivity and accuracy for the determination of QHS and its metabolites. A 3-day validation approach was used for absolute quantitation of QHS and DQHS. The other six metabolites of QHS were semiquantified based on the calibration curve of QHS. The present method was applied to the pharmacokinetic study of QHS in rats after a single oral administration. The data shown here also suggest that this type of mass analyzer will be capable of a quantitative-qualitative workflow.     

线性化求解非线性记录光栅耦合波方程

采用折射率调制特性为上凸型和下凹型的调制曲线,提出了线性化求解非线性记录全息图耦合波方程的方法。以反射相位型全息光栅为例,用耦合波理论分析计算了记录介质折射率调制为上凸型和下凹型调制曲线的体全息图的衍射光谱特性。计算结果表明,折射率调制类型对光栅衍射光谱的带宽有较大影响,对次峰峰值也有影响,而对主峰峰值和峰值位置影响不大。这些结果可以解释实验测得的全息光栅衍射光谱带宽较宽和光栅衍射光谱的多样性。     

Stability of GOY Model Under Modulation of Periodic External Force

There is a phase transition between quasi-periodic state and intermittent chaos in GOY model with a critical value δ0. When we add a modulated periodic externa/force to the system, the phase transition can also be found with a critical value δe. Due to coupling between the force and the intrinsic fluctuation of the velocity on shells in GOY model, the stability of the system has been changed, which results in the variation of the critical value. For proper intensity and period of the force, δe is unequal to δ0. The critical value is a nonlinear function of amplitude of the force, and the fluctuation of the velocity can resonate with the external force for certain period Te.