Photoproduction of ω-Mesons at ELSA and the role of azimuthal asymmetries

Measurements of ω photoproduction of the Crystal-Barrel/TAPS experiment at the ELSA accel-erator of Bonn University are presented which used linearly polarized tagged photon beam from threshold to E_γ = 1700 MeV. The azimuthal asymmetries Σ and Σ_π indicate s-channel resonance contributions on top of the established t-channel exchange processes. These findings are further enhanced by a very first measurement of the G-asymmetry which, in addition to the polarized photon beam, also requires a longitudinally polar-ized proton target. An intuitive interpretation of the specific sensitivity of the azimuthal asymmetries to the reaction mechanisms involved is given.     

Fuzzy关系不定方程当指数为1时求解的简便方法

给出Fuzzy关系不定方程当指数为1时求解的简便方法。     

Regarding the axial-vector mesons

The implications of the f₁(1285)-f₁(1420) mixing for the K₁(³P₁)- K₁(¹P₁) mixing angle are investigated. Based on the f₁(1285)-f₁(1420) mixing angle ∼ 50^° suggested from the analysis for a substantial body of data concerning the f₁(1420) and f₁(1285), the masses of the K₁(³P₁) and K₁(¹P₁) are determined to be ∼ 1307.35±0.63 MeV and 1370.03±9.69 MeV, respectively, which therefore suggests that the K₁(³P₁)- K₁(¹P₁) mixing angle is about ±(59.55±2.81)^°. Also, it is found that the mass of the h^′₁(¹P₁) (mostly of sˉ) state is about 1495.18±8.82 MeV. Comparison of the predicted results and the available experimental information of the h₁(1380) shows that without further confirmation on the h₁(1380), the assignment of the h₁(1380) as the sˉ member of the ¹P₁ meson nonet may be premature.     

Level sets and the minimal time function of linear control processes

We obtain several theoretical results concerning functions defined from an increasing family of subsets of Rⁿ depending on a real parameter and the level sets of an arbitrary function. These results are applied to the study of the minimal time function of a control process described by a linear differential system, under different assumptions on the control restraint set.     

Hadronic η and $ \eta{^\prime}$ decays

The hadronic decays η, ↦3π and ↦ηππ are investigated within the framework of U(3) chiral effective field theory in combination with a relativistic coupled-channels approach. Final state interactions are included by deriving s- and p-wave interaction kernels for meson-meson scattering from the chiral effective Lagrangian and iterating them in a Bethe-Salpeter equation. Very good overall agreement with currently available data on decay widths and spectral shapes is achieved.     

O8h结构磁空间群C-G系数的计算

磁空间群相对于以往的空间群,在对物理图像的描述上更准确、更深刻。如它可在考虑晶体对称性的同时,也考虑到自旋磁矩的作用,因而它的C－G系数更加重要。本文利用本征函数法,计算了面心立方结构Oh^8磁空间群的C－G系数,以及波矢选择规则和C－G序列。     

(γ, π0γ) reaction on a nucleus in the GeV region

π⁰γ invariant mass distribution spectrum has been calculated for the (γ, π⁰γ) reaction on¹²C nucleus at 2.5 GeV beam energy. These π⁰ and γ are assumed to originate due to the decay of vector mesons produced in the photonuclear reaction. The nuclear medium effect on vector mesons and the effect of π⁰ rescattering on the π⁰γ invariant mass spectrum have been investigated     

On the Mixed Propagator Approach to ρ-ω Mixing

The mixed propagator (MP) approach to ρ-ω mixing is discussed. It is found that under the pole-approximation assumption the results of MP approach is not compatible both with the effective Lagrangian theory andwith the experiment measurement criterion. To overcome these inconsistent, we propose a new MP approach in whichthe physical states of ρ and ω are determined by the requirement of experimental measurement to meson resonance. Interms of this new MP approach, the EM pion form factor Fπ and form factors of ρo →π0γ and of ω→πo γ are derived.The results of Fπ are in good agreement with data. The form factor of ρo →π0γ exhibits a hidden charge-asymmetryenhancement effect which agrees with the prediction of the effective Lagrangian theory.     

飞机电缆屏蔽层接地可靠性测试系统设计

飞机电缆屏蔽层可靠接地对飞机建立完整屏蔽环路,防止复杂电磁场对飞机内部电路产生干扰具有重要意义;因此,接地可靠性测试尤为必要;测试系统以NI CompactRIO机箱为核心,通过连接上位机、辅助电路以及测试工具搭建硬件测试平台,利用LabVIEW可视化编程语言编写控制程序;上位机程序,通过状态机实现人工交互以及系统整体逻辑控制;FPGA控制程序,用于驱动硬件完成信号的产生和采集工作;实时处理器程序,采用DMA技术与FPGA进行通讯,对辅助电路反馈的采集数据进行快速傅里叶变换提取有效信号,随后应用矢量电压电流法求解电缆屏蔽层环路阻抗;实际测量结果证明:基于LabVIEW的飞机电缆屏蔽层接地可靠性测试系统能够以较高精度完成电缆屏蔽层接地可靠性测试。     

基于非参数特征提取的早期林火烟雾检测

提出了一种基于非参数特征提取的早期森林火灾烟雾检测方法。采用双背景模型进行运动区域检测,得到可疑烟雾区域。再利用早期火灾烟雾颜色特征和运动特性对提取的可疑运动区域进行颜色判别,对增长区域以及上升区域进行检测,排除部分干扰目标。根据提出的非参数特征提取法,计算并科学地选取可疑区域的特征量,将其输入训练好的支持向量机(SVM)进行烟雾判别。对多段视频进行测试表明,该方法能适用于复杂多变的野外环境,排除干扰,有效地检测出早期林火烟雾。