Au-Au碰撞中大横动量双轻子对的产生(英文)

运用微扰QCD讨论了重离子碰撞中大横动量轻子对的分布, 计算了Au-Au碰撞中两个部分子产生的轻子对的贡献。引入了轻子对产生的直接单光子过程和分解单光子过程。大横动量情况下的所有过程都包括在内, 而且考虑了核遮蔽效应和同位旋效应, 作为QGP背景的双轻子信号有了一个好的修正。The large transverse momentum distribution of lepton pairs produced in heavy-ion collisions has been studied, making use of the perturbative QCD. The contribution of the two parton production process into lepton pairs in Au Au collisions is calculated. Lepton pair production with the direct single photon process and the resolved single photon process are introduced. We believe that the photon processes are significant. The complete processes at large transverse momentum are included, and moreover, the effect of shadowing and isospin of nucleus are also considered in heavy ion collisions. Dilepton signals to regard the background of QGP have a good correction.     

核－核碰撞的独立源模型及中心快度区末态产生粒子横能量分布

将强子－核碰撞的独立源模型推广到核－核碰撞，给出了核－核碰撞末态产生粒子横能量分布方程，将其与ＣＥＲＮ的ＮＡ３５合作组得到的实验数据相比较，模型较好地解释了实验结果．     

孔耦合自由电子激光振荡器光场横向结构特性

孔耦合输出对自由电子激光(FEL)振荡器腔内光场的横向结构有很大的影响, 在输出镜上横模之间发生很复杂的耦合转换。基于中物院远红外自由电子激光振荡器, 研究了 孔输出波导 FEL的数值模拟, 对孔耦合及其引起的腔内光场的变化给以特别的注意, 依据数 值结果, 分析了孔耦合FEL光场横向结构的特性。     

Bending features of a sandwich panel with asymmetric structure under local loads

The bending characteristics of a composite panel with asymmetric layered structure under local surface loads are obtained. A refined version of the applied theory is developed using the analytical solution of the bending problem of a sandwich plate with arbitrary asymmetric structure under a point load. Local effects are investigated within the limits of a discrete model allowing for the specific character of elastic properties of a soft filler. The advantages of the solution are expressions of bending characteristics — layer curvatures, displacements, and stresses — in a closed form. It is shown that these characteristics can vary several times depending on the asymmetry parameters of the structure. Degeneration peculiarities of the solution, stemming from the slipping of layers or, otherwise, their rigid linking by the Kirchoff—Love hypothesis, as well as from account of the transverse shear and compression of the normal, are examined in line with the degeneration of geometric and physical parameters of the discrete model adopted. The results obtained are illustrated by curves and surfaces for the characteristics studied.Submitted for the 11th International Conference on the Mechanics of Composite Materials (Riga, June 11–15, 2000).Institute of Polymer Mechanics, Latvian University, Riga, LV-1006 Latvia. Translated from Mekhanika Kompozitnykh Materialov, Vol. 35, No. 6, pp. 717–742, November–December, 1999.     

Ultrafast transverse thermoelectric response in c‐axis inclined epitaxial La0.5Sr0.5CoO3 thin films

Ultrafast transverse thermoelectric voltage response has been observed in c‐axis inclined epitaxial La_0.5Sr_0.5CoO₃thin films. Voltage signals with the rise time of 7 ns have been detected under the irradiation of pulse laser with duration of 28 ns. A concept, named response rate ratio, has been proposed to evaluate the intrinsic response rate, and this ratio in La_0.5Sr_0.5CoO₃is smaller than that in other reported materials. The low resistivity is thought to be responsible for the ultrafast response, as low resistivity induces small optical penetration depth, and response time has a monotonous increasing relationship with this depth.

     

Study on transition process of vacuum arc under transverse magnetic field

The transverse magnetic field (TMF) drives the vacuum arc to move along the surface of the contacts to prevent the local overheating and melting of the contact surfaces. The arcing process has great influence on the breaking capacity of short‐circuit current. In this paper, the arcing process between three types of TMF contacts was investigated. The transition process of an arc from the ignition stage to the diffusion stage was discussed. The transition moment, transition gap distance, and transition current were obtained. It was found that the axial magnetic field component of TMF contacts affected the arc transition process.     

熔石英亚表面横向划痕调制作用的3维模拟

建立了熔石英后表面3维横向划痕模型,并采用3维时域有限差分方法对熔石英亚表面划痕周围的电场强度进行了数值模拟,分析了划痕宽度、深度、长度以及划痕倾斜角度对入射光场的调制作用,结果表明：随划痕深度和划痕长度的增加,熔石英内的最大电场强度增大,且当划痕长度达到1 μm以上时,最大电场强度趋于稳定;划痕结构因子在1～2之间的划痕较容易引起熔石英损伤;而入射激光在划痕界面和后表面之间发生内全反射时,后表面上的光强增强效果更加明显,因此减少角度范围在20.9°～45°之内的划痕能大幅提高熔石英的损伤阈值。     

装配式混凝土板桥桥面加固技术的试验研究

通过在装配式混凝土板板顶植筋并对桥面施加横向预应力,不但可以加强板与桥面铺装层的连接,而且还可以加强整体结构的横向整体性,增强结构对动载冲击、震动、磨耗抵抗能力.以寨河桥为工程实例,进行了植筋和预应力张拉前后10个工况的混凝土板挠度和应力的现场测试,结果表明,植筋等增加桥面预应力的措施确实能够预防桥面病害的发生,并能提高桥面的承载力,减小挠度,为相关工程提供了依据.     

Multiaxial mechanical behavior of aramid fibers and identification of skin/core structure from single fiber transverse compression testing

The transverse and longitudinal mechanical properties of aramid fibers like Kevlar? 29 (K29) fibers are strongly linked to their highly oriented structure. Mechanical characterization at the single fiber scale is challenging especially when the diameter is as small as 15 µm. Longitudinal tensile tests on single K29 fibers and single fiber transverse compression test (SFTCT) have been developed. Our approach consists of coupling morphological observations and mechanical experiments with SFTCT analysis by comparing analytical solutions and finite element modeling. New insights on the analysis of the transverse direction response are highlighted. Systematic loading/unloading compression tests enable to experimentally determine a transverse elastic limit. Taking account of the strong anisotropy of the fiber, the transverse mechanical response sheds light on a skin/core architecture. More importantly, results suggest that the skin of the fiber, typically representing a shell of one micrometer in thickness, has a transverse apparent modulus of 0.2 GPa. That is around more than fifteen times lower than the transverse modulus of 3.0 GPa in the core. By comparison, the measured longitudinal modulus is about 84 GPa. The stress distribution in the fiber is explored and the critical areas for damage initiation are discussed. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 374–384