An efficient and robust reconstruction method for optical tomography with the time-domain radiative transfer equation

An efficient and robust method based on the complex-variable-differentiation method (CVDM) is proposed to reconstruct the distribution of optical parameters in two-dimensional participating media. An upwind-difference discrete-ordinate formulation of the time-domain radiative transfer equation is well established and used as forward model. The regularization term using generalized Gaussian Markov random field model is added in the objective function to overcome the ill-posed nature of the radiative inverse problem. The multi-start conjugate gradient method was utilized to accelerate the convergence speed of the inverse procedure. To obtain an accurate result and avoid the cumbersome formula of adjoint differentiation model, the CVDM was employed to calculate the gradient of objective function with respect to the optical parameters. All the simulation results show that the CVDM is efficient and robust for the reconstruction of optical parameters.     

Hydrodynamic limits for kinetic equations and the diffusive approximation of radiative transport for acoustic waves

We consider a class of kinetic equations, equipped with a single conservation law, which generate -contractions. We discuss the hydrodynamic limit to a scalar conservation law and the diffusive limit to a (possibly) degenerate parabolic equation. The limits are obtained in the ``dissipative' sense, equivalent to the notion of entropy solutions for conservation laws, which permits the use of the perturbed test function method and allows for simple proofs. A general compactness framework is obtained for the diffusive scaling in . The radiative transport equations, satisfied by the Wigner function for random acoustic waves, present such a kinetic model that is endowed with conservation of energy. The general theory is used to validate the diffusive approximation of the radiative transport equation.

     

中低Z材料辐射烧蚀实验研究

 在星光Ⅱ激光装置上,利用波长为0.35μm的激光注入柱腔金箔靶产生的金箔后向X光作源,烧蚀中低Z样品材料,通过空间分辨测量靶源区和样品自发辐射X光的时间过程获得了中Z铝材料的辐射烧穿时间结果;在北京同步辐射源上对透射光栅进行了实验标定。     

MCDF程序包和电偶极辐射跃迁几率的相对论计算程序

本文讨论如何利用Grant等多组态Dirac-Fock(MCDF)程序包(1980)中的现成资源,依据相对论辐射跃迁的普遍理论,计入组态相互作用和跃迁中的轨道驰豫效应,在Coulomb规范和长度规范下,续编原子的电偶极辐射跃迁几率的计算程序。     

Radiative Transport in a Periodic Structure

We derive radiative transport equations for solutions of a Schrödinger equation in a periodic structure with small random inhomogeneities. We use systematically the Wigner transform and the Bloch wave expansion. The streaming part of the radiative transport equations is determined entirely by the Bloch spectrum, and the scattering part by the random fluctuations.     

B c meson properties and its leptonic radiative decays

The properties of the meson B _c are outlined. The leptonic radiative decays for B _c meson are presented. An outlook on the studies of the meson is given.     

NO_2分子激光诱导荧光辐射寿命和碰撞猝灭速率的实验研究

实验测定了激发波长在 591～ 594nm范围 ,压力在 0 .1～ 15Pa时 ,NO2 分子激光诱导荧光衰减曲线 ,作几何修正后应用Stern Volmer模型 ,得到了零压辐射寿命τ0 ( =1/k0 )和碰撞猝灭速率常数kq,结果与文献报道基本一致。对NO2 分子激发态能级的反常长寿命和一定压力下出现的双指数衰减等进行了较详细的讨论。     

类锂等电子系列高位三激发态2p2np4So能量和到1s2pmp4P态的辐射跃迁

利用多组态相互作用方法及Rayleigh-Ritz变分法,计算了类锂离子2p²np⁴S^o(n=2—4)和1s2pmp⁴P(m=2,3)的能量.运用截断变分方法得到能量的改进量.计算了相对论修正、质量极化效应,从而获得了高精度的能量计算值.同时还计算了该系统之间的辐射跃迁波长、振子强度和辐射跃迁率.计算结果与实验符合得很好. 关键词： 三激发态 类锂离子 振子强度 辐射跃迁     

Properties of Charmonium States in a Phenomenological Approach

We investigate the spectrum and decay rates of charmonium states within the framework of the non relativistic quark model by employing a Coulomb like potential from the perturbative one gluon exchange and the linear confining potential along with the potential derived from instanton vacuum to account for the hyperfine mass splitting of charmonium states in variational approach. We predict radiative E1, M1, two-photon, lepton and two-gluon decay rates of low lying charmonium states. An overall agreement is obtained with the experimental masses and decay widths.We have estimated the branching ratio of two gluons decaying into light hadrons.     

Study of the XYZ states at the BESIII

With its unique data samples at energies of 3.8–4.6 GeV, the BESIII experiment made a significant contribution to the study of charmonium and charmonium-like states, i.e., the XYZ states.We review the results for observations of the Z_c(3900) and Z_c(4020) states, the X(3872) in e⁺e⁻ annihilation, and charmonium ψ(1³D₂) state, as well as measurements of the cross-sections of ωχ_cJ and ηJ/ψ, and the search for e⁺e⁻→ γχ_cJ and γY (4140). We also present data from BESIII that may further strengthen the study of the XYZ and conventional charmonium states, and discuss perspectives on future experiments.