MULTIDIMENSIONAL UPWIND RESIDUAL DISTRIBUTION SCHEMES FOR THE CONVECTION–DIFFUSION EQUATION

Multidimensional residual distribution schemes for the convection–diffusion equation are described. Compact upwind cell vertex schemes are used for the discretization of the convective term. For the diffusive term, two approaches are compared: the classical finite element Galerkin formulation, which preserves the compactness of the stencil used for the convective part, and various residual-based approaches in which the diffusive term, evaluated after a reconstruction step, is upwinded along with the convective term.     

Measurement of the Michel parameter rho in muon decay

The TWIST Collaboration has measured the Michel parameter rho in normal muon decay, mu(+)--> e(+)nu(e)nu (mu). In the standard model, rho = 3/4. Deviations from this value imply mixing of left- and right-handed muon and electron couplings. We find rho=0.750 80+/-0.000 32(stat) +/- 0.000 97(syst) +/- 0.000 23, where the last uncertainty represents the dependence of rho on the Michel parameter eta. This result sets new limits on the W(L)-W(R) mixing angle in left-right symmetric models.     

The mass of 20Mg: A test of the isobaric multiplet mass equation in A=20

The reaction ²⁴Mg(⁴He, ⁸He)²⁰Mg has been used to determine the mass of ²⁰Mg. The resulting mass excess of 17.57±0.03 MeV is used to test the isobaric multiplet mass equation in A=20. A small deviation from the quadratic mass equation is found.     

Observation of polarization in bottomonium production at square root of s = 38.8 GeV

We present a measurement of the polarization observed for bottomonium states produced in p-Cu collisions at square root of s = 38.8 GeV. The angular distribution of the decay dimuons of the Upsilon(1S) state shows no polarization at small values of the fractional longitudinal momentum x(F) and transverse momentum p(T) but significant positive transverse production polarization for either p(T)>1.8 GeV/c or for x(F)>0.35. The Upsilon(2S+3S) (unresolved) states show a large transverse production polarization at all values of x(F) and p(T) measured. These observations challenge NRQCD calculations of the polarization expected in the hadronic production of bottomonium states.     

电感耦合等离子体原子发射光谱(ICP-AES)法测定铅锭中11种杂质元素

研究了用酸分解试样后不需分离基体直接用电感耦合等离子体原子发射光谱(ICP-AES)法测定铅锭中银、铜、铋、砷、锑、锡、锌、铁、镉、镍、铊11种杂质元素的方法。优化了样品前处理条件及仪器检测条件。方法的检出限为0.0012～0.0168μg/mL,回收率为89%～110%,RSD为2.3%～5.0%。方法简便快速,检出限低,精密度和准确度能满足铅锭中杂质元素的检测要求,具有较强的实用性和可操作性,可用于铅锭中杂质元素的测定。     

共振辐射的理论研究——Holstein方程的解

解决介质中共振辐射的关键问题是求解Holstein方程。本文直接利用算符运算将方程积分,给出了激发态粒子集居数的含无限项的级数表达式。基于对这个级数高阶系数的极限行为的研究,成功地克服了无穷项求和的困难,整理出一个在任意给定精度下都只含有限项的解式,由它可以计算出任何时刻的结果。 关键词：     

Particle-hole nature of the two lowest 3−states in 24Mg

Stripping and pickup reactions are performed and show the configuration for the lowest 3^?state (7.62MeV) to be mainly a hole in the 1p shell the next 3^?level (8.36 MeV) is mainly promoted into the 2p-1f shell.     

壳聚糖膜固定生物活性短肽RGDS的研究

为改善壳聚糖对细胞的特异性吸附,采用水溶性碳二亚胺将生物活性短肽精氨酸-甘氨酸-天冬氨酸-丝氨酸(RGDS)固定到壳聚糖膜的表面,采用X射线光电子能谱检测固定多肽前后的壳聚糖膜表面,发现反应后壳聚糖膜表面氮元素含量增大,Nls和Cls曲线拟合谱中酰胺键增多,表明RGDS短肽已固定到壳聚糖膜的表面;人角膜缘上皮细胞体外培养实验表明,固定RGDS后壳聚糖膜的细胞黏附率有了明显提高,固定RGDS后的壳聚糖膜在角膜组织工程支架等方面有更好的应用潜力。     

Astrophysical S-factors from asymptotic normalization coefficients

S-factors for direct capture reactions can be found at astrophysical energies from asymptotic normalization coefficients which provide the normalization of the tail of the overlap function. For example the overlap for ⁸B → ⁷Be+p defines the S-factor for ⁷Be (p, γ)⁸B. Peripheral transfer reactions offer a technique to determine these asymptotic normalization coefficients. As a test of the technique, the ¹⁶O(³He, d)¹⁷F reaction has been used to determine asymptotic normalization coefficients for transitions to the ground and first excited states of ¹⁷F. The S-factors for ¹⁶O(p, γ)¹⁷F calculated from these ¹⁷F → ¹⁶O+p asymptotic normalization coefficients are found to be in very good agreement with recent measurements. Following the same technique, the ¹⁰B(⁷Be, ⁸B)⁹Be and ¹⁴N(⁷Be, ⁸B)¹³C reactions have been used to measure the asymptotic normalization coefficient for ⁷Be(p, γ)⁸B. This result provides an indirect determination of S ₁₇(0).