A modification potential method of calculating total cross sections of electrons scattering from complex molecules C2H6, C2F6, C6H6 and C6F6 at 100 eV-5000 eV

A complex optical model potential modified by incorporating the concept of bonded atom, which takes into consideration the overlapping effect of electron clouds between two atoms in a molecule, is first employed to calculate the total cross sections for electrons scattering from such complex molecules as C总交叉断面 电子散射 添加规则 原子分子碰撞 电子云total cross section, electrons scattering, additivity rule, atomic and molecular collisionProject supported by the National Natural Science Foundation of China (Grant No 10574039).2005-11-102005-11-102005-11-30A complex optical model potential modified by incorporating the concept of bonded atom, which takes into consideration the overlapping effect of electron clouds between two atoms in a molecule, is first employed to calculate the total cross sections for electrons scattering from such complex molecules as C2H6, C2F6, C6H6 and C6F6 using the aclditivity rule model at Hartree-Fock level over the energy range from 100 eV to 5000 eV. The total cross sections are quantitatively compared with those obtained by experiments wherever available, and they are in good agreement with each other over a wide energy range. It is shown that the modified potential together with the additivity rule model is completely suitable for the calculation of total cross sections of electrons scattering from such complex molecules as C2H6, C2F6, C6H6 and C6F6 above 200 eV-300 eV.     

正则*-断面的一个分类(英文)

本文从(2,1)-代数簇的角度对具有正则*-断面的正则半群进行研究,给出了该簇及其若干子簇的一些刻画.事实上,本文给出了正则*-断面的一个分类.     

一种基于收费数据的断面流量估算方法

高速公路的流量是反映高速公路交通状态的一个重要参数.目前,针对高速公路断面流量的采集主要依靠人工方式或者通过安装一些车流检测设备来获得,成本较高.结合高速公路收费系统的特点,通过对收费数据的统计分析,提出一种基于收费数据估算高速公路断面流量的方法.首先,对收费数据进行初步的处理,从中计算出行驶时间;然后,根据收费数据中的车辆信息统计出各个OD的交通流量;最后,结合各个收费站出入口的位置信息、路段行驶速度信息以及OD流量来估算断面的交通流量.     

Slow Wave Characteristics of Helix Structure with Elliptical Cross Section

We present a novel helix slow wave structure with an elliptical cross section shielded by an elliptical waveguide. The rf characteristics including dispersion properties, interaction impedance of zero mode in this structure have been studied in detail. The theoretical results reveal that weaker dispersion even abnormal dispersion characteristics is obtained with the increasing eccentricity of the elliptical waveguide, while the interaction impedance is enhanced by enlarging the eccentricity of elliptical helix.     

粉尘云激波点火现象实验研究

利用新型两相激波管成功地研究了中等强度入射激波诱导的均匀悬浮粉尘间断面点火现象。平均直径为１０ｍ的玉米粉尘由流化床均匀地分散在氧气或空气中。悬浮粉尘间断面激波点火过程由纹影法连续拍摄。结果表明:颗粒浓度对点火延迟时间影响不大，空气中的玉米粉尘点火延迟大于氧气中的值，低马赫数激波条件下尤为明显。     

聚氯乙烯断面特征区及粗糙度与断裂能的关系

以往对聚合物材料的断面粗糙度与力学性能关系的研究主要是针对断面总体粗糙度进行的,忽略了断裂的不同阶段及不同的断裂机制在断面上产生的相应的特征区对力学性能参数的影响,导致如文献［１］、［２］中得出的粗糙度参数与断裂能耗间的数据关系存在较大的分散性．本文...     

聚苯乙烯断面形貌特征参量对断裂能耗的影响

对缺口聚苯乙烯试样进行了不同加载速率下的三点弯曲实验,通过对加载速率、断面特征区特征参量、断裂能耗三者间关系的分析,指出断裂表面特征形貌中的镜面区、肋状区的形成是能量消耗的主要过程．实验结果表明,随着加载速率增大,镜面区尺寸增大并逐渐趋于平缓,肋条宽度减小而肋区粗糙度增大．断裂能耗与加载速率间存在极小值现象,该极小值出现在２５ｍ／ｍｉｎ的加载速率下,与断面形貌特征的变化正好对应;加载速率＜２５ｍ／ｍｉｎ时,断面主要由镜面区、最后断裂区组成,断裂能耗的变化取决于镜面区尺寸的变化;加载速率＞２５ｍ／ｍｉｎ时,断面由镜面区、肋区、最后断裂区组成,断裂能耗的变化主要和肋区粗糙度的变化有关．     

EFFECT OF MONTMORILLONITE ADDITION ON MECHANICAL CHARACTERIZATIONS OF POLYIMIDE NANOCOMPOSITE FILMS

Tensile deformation and fracture characteristics of polyimide/montmorillonite nanocomposite films are investigated to enhance the particular mechanical properties and understand the effective factors in dominating the mechanical properties of nanocomposites, such as the nanolayer, matrix and nanolayer/matrix interface. How to contribute to the mechanical properties of nanocomposite film is a very complex problem. In this paper, these factors are analyzed based on the addition amount and fracture mechanics. The results indicate that the specimen at 20 wt% MMT breaks prematurely with a fracture strength （σb = 78 MPa） much lower than that （σb = 128 MPa） at the 1 wt% MMT. However, the Young＇s modulus （3.2 GPa） of the former is higher than that （1.9 GPa） of the latter. Fractography also indicates that the brittle cracking formed in high content addition is the main cause of failure but microscopically ductile fracture morphology still exists locally. And for the trace element addition, the smaller threading slipping veins are evenly distributed on the entire fracture section of these films. Therefore, these characteristics would presumably be associated with both the concentration effects of size of nanocomposite sheets and the increasing deformation harmony in nanolayers.     

Discussion on Cross Section Measurement for D^-D Production around ψ（3770）

We give a brief discussion on the measurement of the cross section for D^-D production around the ψ（3770） resonance, and point out a new calculation of the cross sections based on the absolute measurements. Compared with single tag and double tag analyses, the new calculation provides us with many more opportunities to perform the cross section measurement.     

Precise measurement of the e^＋e^- →π^＋π^-（γ） cross section with the initial state radiation method at BABAR

We present a precise BABAR measurement on the cross section of the process e^＋e^- →π^＋π^-（γ） from threshold to an energy of 3 GeV with the initial state radiation （ISR） technique, using 232 fb^-1 of data collected with the BABAR detector at e^＋e^- center-of-mass energies near 10.58 GeV. The ISR luminosity is determined from a study of the leptonic process e^＋e^- →μ^＋μ^-γ（γ）. The leading-order hadronic contribution to the muon magnetic anomaly calculated using the ππ cross section measured from threshold to 1.8 GeV is （514.1± 2.2（stat） ± 3.1（syst）） × 10^-10.