强流束在二极磁铁中的非线性传输—Lie代数分析

 用Lie代数方法分析了带电粒子束在二极磁铁中的非线性传输，包含了空间电荷效应。粒子在相空间中的分布采用K V分布。轨迹分析的结果做到二级近似，根据需要，还可以扩展到三级或更高级近似。在分析中，将磁铁沿中心轨道分成若干小段。在每个小段上利用所得公式进行轨迹计算，得到自洽的解。然后重复此过程，作下一小段的计算，直到最后一个小段为止。     

结合神经网络的换热器积分近似模型

为解决换热器的分布参数模型存在的精度与计算代价之间难以调和的矛盾,本文提出了一种新的方法,即光用一个积分近似模型作为对原分布参数模型的简化,而仅对积分近似中某些非线性关系用神经网络来表达。该方法用于翅片管式冷凝器的实际计算,验证了这一思路的有效性。     

双扩散晶体管的基区渡越时间和注射效率

本文简要介绍在对扩散杂质分布作了近似之后（在发射区和基区漂移场加速区中近似为 指数型分布,而发射结区和基区漂移场减速区中近似为线性分布）,计算了双扩散晶体管的基 区输运系数、基区渡越时间和注射效率．在讨论中着重指出,为了减小基区渡越时间以提高频 率性能,应该如何全面考虑．     

钛扩散LiNbO3单模波导场分布

给出了 Ti 扩散 LiNbO₃条波导任意阶导模场分布的近似解,通过逐点近似法确定待定常数,分析了它的物理意义,也给出了导模的传播常数和有效折射率的解析式,与变分法相比,这种方法物理概念明确,计算量小,寻优简单,为集成光学的设计提供了一种计算精度较高的计算方法.     

近贴聚焦开口式微通道板象增强器调制传递函数的近似计算

提出了根据微通道板输出电子轴向能量分布的测量原理,近似计算由微通道板和荧光屏组成的近贴聚焦开口式象增强器调制传递函数(MTF)的数值方法。讨论了近似方法带来的计算误差及提高计算准确性的可能途径。     

平行板间方势阱偶极流体的结构性质研究

在密度泛函理论(DFT)框架下, 应用改进的基本度量理论(MFMT)表达硬球作用对自由能泛函的贡献, 根据统计力学理论结合加权密度近似(WDA)表达偶极作用对自由能泛函的贡献,得到了方势阱偶极流体在平行板间的密度分布表达式, 计算了偶极流体在两平行板间的密度分布, 并探讨了方势阱深度和宽度对体系密度分布的影响. 此外, 通过体系密度分布, 进一步分析了方势阱宽度和深度以及板间尺度与溶剂化力的关系.     

平行板间方势阱偶极流体的结构性质研究

在密度泛函理论(DFT)框架下, 应用改进的基本度量理论(MFMT)表达硬球作用对自由能泛函的贡献, 根据统计力学理论结合加权密度近似(WDA)表达偶极作用对自由能泛函的贡献,得到了方势阱偶极流体在平行板间的密度分布表达式, 计算了偶极流体在两平行板间的密度分布, 并探讨了方势阱深度和宽度对体系密度分布的影响. 此外, 通过体系密度分布, 进一步分析了方势阱宽度和深度以及板间尺度与溶剂化力的关系.     

微波矩孔衍射仿真与实验

从基尔霍夫标量式出发,在振幅零级近似和相位一级近似条件下,由Mathematica仿真计算获得微波经不同尺寸矩孔的衍射分布,并在微波光学实验仪上进行实验验证,获得了从夫琅禾费衍射向菲涅尔衍射转化的衍射花样,实验与仿真结果较为吻合。     

光谱仪谱线和谱带弯曲现象的精确表述方式

在矢量衍射理论基础上给出了任意倾斜入射下的光栅方程一般形式以及衍射极角和衍射方位角的完整解析表达式,由此首次导出了平面光栅光谱仪谱线和谱带弯曲量的精确计算公式和对应于衍射极角和衍射方位角的两类角色散公式,比较了谱线弯曲精确公式和近似公式的计算结果,进而指出和弥补了近似公式的不足,并数值考察了入射狭缝高度对光谱仪色散能力的影响程度。由于在以上各式的推导过程中未作任何近似,且涉及到了导致谱线和谱带弯曲的所有可能因素,因而它要比以往所用近似公式更为全面和可靠,可作为实际光谱仪器设计、测试、装调和使用的理论依据。     

与压缩真空相互作用的具有强度耦合的广义Kaynes—Cummings模型 …

考虑具有强度耦合的广义Ｊａｙｎｅｓ－Ｃｕｍｍｉｎｇｓ模型与压缩真空相互作用。根据Ｐｅｇｇ和Ｂａｍｅｔｔ新的相位理论,不仅得到了压缩真空场的相位分布,相位期待值和相位涨落的普遍表示式,及其演化图示,而且还导出了弱压缩真空和强压缩真空情形的近似角极表示式。对于压缩真空的压缩量与相位特性之间的关系进行了简要讨论。     

平面波经小圆孔非傍轴衍射的轴上光强解析分析

用亥姆霍兹 基尔霍夫积分定理和基尔霍夫边界条件,推导出了平面波经小圆孔非傍轴衍射时轴上强度的简单解析表达式,研究了平面波经小圆孔后整个衍射空间非傍轴的轴上光强分布.给出了计算圆孔菲涅尔数的精确公式,重新检查了通常的菲涅尔数公式的有效性.数值计算显示,应用解析表达式所得的结果与应用衍射积分公式所得的结果完全一致.     

On the connection of the formulas for entropy and stationary distribution

As is well known in statistical physics, the stationary distribution can be obtained by maximizing entropy. We show how one can reconstruct the formula for entropy knowing the formula for the stationary distribution. A general case is discussed and some concrete physical examples are considered.     

稠密热等离子体的电子传导不透明度研究

 采用相对论自洽场平均离子势模型，电子简并效应采用Fermi–Dirac分布描述，参数结构因子用来考虑离子结构的影响，电子对离子的散射截面采用分波分析，利用推广的Ziman公式对稠密热等离子体的电子传导不透明度作了大量计算，并将结果与实验值和其它理论值作了比较。     

Equivalence of Euclidean and Wightman field theories

A new inversion formula for the Laplace transformation of tempered distributions with supports in the closed positive semiaxis is obtained. The inverse Laplace transform of a tempered distribution is defined by means of a limit of a special distribution constructed from this distribution. The weak spectral condition on the Euclidean Green's functions implies that some of the limits needed for the inversion formula exist for any Euclidean Green's function with an even number of variables. We then prove that the initial Osterwalder-Schrader axioms [1] and the weak spectral condition are equivalent with the Wightman axioms.The research described in this publication was made possible in part by Grant No. 93-011-147 from the Russian Foundation for Basic Research     

On Higgs Boson Production via Gluon Fusion

A simple phenomenological formula for the gluon distribution function in a proton is proposed. The reported results of calculations of the cross section of Higgs boson production via gluon fusion with higher-order QCD radiative corrections are reproduced using this formula and the one-loop amplitude.     

Nuclear size correction to the hyperfine splitting in low- hydrogen-like atoms

The finite nuclear size effect on the hyperfine splitting of low-Z hydrogen-like atoms is studied in the external field approximation. A simple non-relativistic formula is proposed which expresses the nuclear size correction to the hyperfine splitting in terms of moments of the nuclear charge and magnetization distribution. The numerical results obtained via this formula are compared with corresponding results derived by means of the Zemach formula. A relativistic formula for the nuclear size correction to the hyperfine splitting is also derived. Received 18 March 2002 / Received in final form 14 November 2002 Published online 28 January 2003 RID="a" ID="a"e-mail: plunien@physik.tu-dresden.de     

Tunneling ionization of atoms with excitation of the core

A general formula is obtained for the probability of tunneling ionization of an atom accompanied by excitation of the core. This formula is a generalization of the Carlson formula for the probability of a single-photon two-electron transition in atoms. The limiting case of this formula, just as that of the Carlson formula, is the well-known random-perturbations approximation. Numerical results are presented for Zn, Sr, and Cd atoms. For these atoms the contribution of the excited states of singly charged ions to the probability of the formation of doubly charged ions is a nonmonotonic function of the laser radiation intensity. Analysis of the tunneling ionization of molecules shows that with overwhelming probability an ion is formed in the ground vibrational state, while for the standard photoionization the distribution over vibrational states is determined by the Franck-Condon factors.     

Study On Laser Fiber Diameter Measurement Instrument

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Urbaryon Model Approach to Unified Understanding of Large and Small PT Spectra

Single-particle distributions in the entire Peyrou plot at CERN-PS ∼ ISR energies are unifiedly described by the whole-region formula, which incorporates both parton model results at large p_T and all of the Mueller-Regge forms at small p_T. The quantum number dependence of the distributions is explained by the formula as due to the intimate relation between the energy-momentum flow and the quantum-number flow carried by valence urbaryons. A field theoretical basis of the formula is provided by a covariant model of the hadron-urbaryon amplitude which is parametrized in terms of valence urbaryon lines and pair effects. Two-body reactions at all angles are also described by the formula as the exclusive limit of inclusive reactions. The construction of a formula for inclusive two-particle distribution is briefly discussed.     

穿孔管消声器声学长度修正的理论公式

推导出穿孔管消声器声学长度修正以及共振频率的理论公式。证明了在均匀分布情况下,多小孔向膨胀腔声辐射与单个小孔向膨胀腔声辐射的声学长度修正系数是一致的。对于小孔向主管道的声辐射,根据理论公式研究了穿孔率、周向均布数以及亥姆赫兹数对声学长度修正的影响,有限元计算得出在直径比小于0.4的情况下声学长度修正系数理论公式与仿真计算结果吻合良好。并利用理论公式的性质以及仿真结果获得了实用的拟合公式,提升了穿孔管消声器在高频时共振频率的计算精度。