Net Charge Fluctuation and String Fragmentation

We present the simulation results of the net charge fluctuation in Au Au collisions at √Snn=130 GeV from a dynamic model, JPCIAE, and its revisions. The simulations are done for the quark-gluon matter, the directly produced pions, the pion matter, and the hadron matter. The simulated net charge fluctuation of the quark-gluon matter is close to the thermal model prediction for the quark-gluon gas. However, the discrepancy exists comparing the simulated net charge fluctuation for directly produced pions and the pion matter with the thermal model prediction for pion gas and the resonance pion gas, respectively. The net charge fluctuation of hadron matter from default JPCIAE simulations is nearly 3.5 times larger than quark-gluon matter. A discussion is given for the net charge fluctuation as an evidence of QGP phase transition.     

聚苯乙烯/有机合成锂皂石纳米复合材料的制备与表征

聚苯乙烯/有机合成锂皂石纳米复合材料的制备与表征     

Di‐Channel Polyfluorene Containing Spiro‐Bridged Oxadiazole Branches

Summary: A p–n di‐channel copolymer based on polyfluorene (PF) has been designed and prepared. Branches containing oxadiazole units are attached to the PF backbone through the spiro‐structure and act as channels to improve the electron affinity; these branches form a steric ‘di‐channel’ framework with the polymer backbone. The polymer possesses excellent thermal stability. The lowest unoccupied molecular orbital energy level of the polymer is significantly altered in comparison with poly(9,9‐dioctylfluorene‐2,7‐diyl).

Schematic of the di‐channel polyfluorene synthesized here and the mechanism of energy transfer through the structure.     

碳钢阳极电溶解过程的电化学振荡现象

金属和合金阳极电溶解过程中常常可以观察到电化学振荡现象,尤其是在活化与钝化的转变阶段,碳钢／H2SO4／Pt体系在活化－钝化转变过程中狭窄的电位范围内可以产生多种类型的电流振荡,如阻尼振荡、周期振荡、准周期振荡和混沌等,对其振荡机理进行了初步分析和讨论。     

钢管定购和运输的策略优化

本文为图 1主管道和图 2树形管道的定购和运输计划给出了一个最优化模型 .通过解这一个最优化模型得到钢管的定购和运输的最优策略 .同时 ,分析了哪个钢厂钢管销价的变化对图 1主管道购运计划和总费用影响最大 ,哪个钢厂钢管产量的上限的变化对购运计划和总费用影响最大     

旗流形的上同调环的自同态

本文应用李群理论,对紧单李群Ｇ,给出了旗流形 Ｇ／Ｔ的上同调环自同态的完全分类,并对典型群计算了相应自同态的Ｌｅｆｓｃｈｅｔｚ数．     

1Cr18Ni9Ti不锈钢的非比例循环强化性能

对1Cr18Ni9Ti不锈钢进行了各种比例和非比例循环本构实验,其中包括圆路径、正方形、正菱形、蝶形、三角形和两种十字形应变路径。表明其具有明显的非比例循环附加强化。在相同的等效应变幅值上,材料的附加强化与路径密切相关。对于圆路径,其附加强化度最大可达60％。通过对不同应变历史的实验研究表明,先前小的非比例度的加载历史对后继大的非比例度路径的强化没有影响;而先前大非比例度的加载路径对后继小非比例度路径的循环强化有较大影响。     

Resonant and Stationary Waves in Rotating Disks

The analytical conditions for resonant and stationary waves inrotating disks are presented. These conditions are derived from anonlinear plate theory pertaining to initial configurations and areapplicable to rotating disks with initial waviness and/or undergoinglarge-amplitude displacements. The rotational speeds at which theresonant and stationary waves occur for a 3.5-inch diameter computermemory disk are computed. The resonant waves for linear and nonlinear,rotating disks are simulated numerically. It is found that some diskmodes exhibit a hardening effect under which the rotational speeds forthe resonant and stationary waves increase with increasing waveamplitude, while other modes experience a softening effect with thoserotational speeds decreasing with increasing wave amplitude. Therotating-disk resonant spectrum presented in this paper is relevant tothe disk drive industry for determining the range of operationalrotation speed.     

Speckle characteristics of simulated deep Fresnel region under shadowing effect

After the three-dimensional self-affine fractal random surface simulation, we use the optical scattering theory to calculate the deep Fresnel region speckle(DFRS) under consideration of the more strict shadowing effect. The evolution of DFRS with the scattering distance and the intensity probability distribution are studied. It is found that the morphology of the scatterer has an antisymmetric relationship with the intensity distribution of DFRS, and the effect of micro-lenses on the scattering surface causes the intensity probability distribution of DFRS to deviate from the Gaussian speckle in the high light intensity area.     

联萘酚多氢键硫脲催化合成1,4-二氢吡啶衍生物

本文合成了三种具有多氢键的联萘酚轴手性硫脲催化剂,并将其用于催化合成1,4-二氢吡啶衍生物。结果显示,所合成的新型多氢键硫脲均表现出较好的催化作用,能有效地提高1,4-二氢吡啶衍生物的收率和对映选择性。所有新化合物结构均经过¹H NMR、¹³C NMR、IR、熔点等表征所确认。