TP-LIF技术测量甲烷-空气火焰中CO的相对浓度分布

阐述了双光子激光诱导荧光(TP-LIF)技术的原理及线性模型,利用双光子过程激励CO分子B1∑+←←X1∑＋(0,0)带Q支的跃迁(约230 nm),分析了B1∑+→A1Π荧光带的荧光光谱特性,探讨了激光功率密度、激光波长及火焰温度等因素对测量的影响,并给出甲烷-空气火焰在一定燃烧条件下CO分子浓度随火焰位置及高度的变化关系。实验结果表明,利用TP-LIF技术测量CO的浓度分布,其时空分辨率及探测灵敏度都很高。当激光功率密度较强时,TP-LIF信号和激光能量成线性关系,而且由于光电离速率的增强,大大降低了碰撞猝灭速率等环境因素对信号测量造成的影响,该特性对实验标定及定量测量都非常有帮助。     

12 MeV直线感应加速器主开关的优化设计

介绍了12MeV直线感应加速器主开关的一种优化设计。在保持原有主开关的设计风格和接口结构的条件下,通过优化设计局部结构和调整开关电极尺寸,把主开关的结构电感从63.7nH减小到35nH,使得加速腔的高压脉冲前沿从39.6ns减小到27ns,从而有利于提高12MeV直线感应加速器的性能,验证了优化设计的可行性。     

角锥棱镜激光谐振腔的基本特性

分析了角锥棱镜对光束的相位变换作用,带二面角误差的角锥棱镜可等效于6块光楔的组合,其楔角的大小和方向由二面角误差决定。对在腔内往返传输的光线在镜面上的位置进行了分析,结果表明：3个二面角误差相同且不为零的角锥棱镜构成的谐振腔为约束非稳腔。用Fox-Li迭代法数值模拟得到了不同棱镜二面角误差情况下的谐振模式。模拟结果表明：圆形镜腔情况下基本振荡模式接近于TEM03模的拉盖尔高斯光束;当3个二面角误差不相同时,模式中各个区域的强度分布不对称。采用3个二面角误差基本接近且绝对值较小的棱镜可以提高光束质量。     

脉冲准分子激光淀积薄膜的实验研究

利用两种脉宽(30ns,500fs)的KrF准分子激光展开了淀积类金刚石薄膜的实验研究,并且成功地制备了大面积不含氢成分的HF-DLC薄膜,运用时空分辨的等离子体发射光谱诊断系统和离子探针系统研究了等离子体特性对薄膜性能的影响。尝试了利用准分子激光制备非晶硅薄膜,研究了实验参数对非晶硅薄膜制备的影响,并分析了制备具有良好电学和光学性能的非晶硅薄膜的条件。     

Convergence theorems for implicit iteration process for a finite family of continuous pseudocontractive mappings

In this paper, a necessary and sufficient conditions for the strong convergence to a common fixed point of a finite family of continuous pseudocontractive mappings are proved in an arbitrary real Banach space using an implicit iteration scheme recently introduced by Xu and Ori [H.K. Xu, R.G. Ori, An implicit iteration process for nonexpansive mappings, Numer. Fuct. Anal. Optim. 22 (2001) 767-773] in condition αn∈(0,1], and also strong and weak convergence theorem of a finite family of strictly pseudocontractive mappings of Browder-Petryshyn type is obtained. The results presented extend and improve the corresponding results of M.O. Osilike [M.O. Osilike, Implicit iteration process for common fixed points of a finite family of strictly pseudocontractive maps, J. Math. Anal. Appl. 294 (2004) 73-81].     

自反Banach空间中非扩张非自映射的粘滞迭代逼近方法

主要在自反和严格凸的且具有一致G(a)teaux可微范数的Banach空间中研究了非扩张非自映射的粘滞迭代逼近过程,证明了此映射的隐格式与显格式粘滞迭代序列均强收敛到它的某个不动点.     

The spin-one Ising model in the mean-spherical approximation

The spin-one Ising ferromagnet on a simple cubic lattice is treated in the mean-spherical approximation (MSA) for an exchange potentialJ(r) parametrized by a Kac-Baker inverse-range parameter γ. The mean-field result is recovered when γ→ 0; in this limit the result is exact. For γ≠ 0, a detailed analysis is given of the phase separation associated with the tricritical point that occurs. The analysis is made through the relation that gives the internal energy viaJ(r). It shows that the MSA result satisfactorily captures the important thermodynamic features of the tricritical point as long as γ is not too large. The case of CoulombicJ(r) is also considered; hereJ(r) is antiferromagnetic. An argument is given in support of the expectation that on the simple cubic and body-centered cubic lattices the CoulombicJ(r) will give rise to a tricritical point at which a λ-line of Néel points meets a paramagnetic-antiferromagnetic coexistence boundary.     

Morphology evolution of nanocomposites based on poly(phenylene sulfide)/poly(butylene terephthalate) blend

Poly(phenylene sulfide) (PPS)/poly(butylene terephthalate) (PBT) (60/40 w/w) blend nanocomposites (PPS/PBTs) were prepared by direct melt compounding of PPS, PBT, and organoclay. The morphology and rheology of PPS/PBTs were investigated using scanning electron microscope and transmission electron microscope as well as parallel plate rheometer. The intercalated clay tactoids are selectively located in the continuous PBT phase due to their nice affinity. A novel morphology evolution of the immiscible blend matrices is observed with increase of clay loadings. Small addition of clay increases the discrete PPS spherulite domain size. With increasing loading levels, the PPS phase transform to the fibrous structure and finally, to the partial laminar structure at the high loading levels, in which shows a characteristic of large‐scaled phase separation. The presence of clay, however, does not impede the coalescence of the PPS phase because the phase size increases with increasing clay loadings. The elasticity and blend ratio of two matrices are proposed as the important roles on the morphological evolution. Moreover, the laminar structure of PPS phase is very sensitive to the steady shear flow and is easy to be broken down to spherulite droplet at the low shear rate. However, high shear level is likely to facilitate the coalescence of those PPS phase and finally to phase inversion, both contributing to increases of the dynamic modulus after steady shear flow. In conclusion, the morphology of the immiscible polymer blend nanocomposites depends strongly on both the clay loadings and shear history. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 1265–1279, 2008     

Correlation functions in the cavity model of ionic fluids

The dominant long-range contribution of the solute-solvent interaction to ion-ion distribution functions is assessed in a limit that yields the cavity model of ionic solutions.This paper is based upon a presentation given at the 71st Statistical Mechanics Meeting, May 1994.     

Statistical mechanical model with chemical reaction

We study a mixture of classical particles where unequal particles interact with strong binding forces, while equal particles repel each other with a hard-core interaction. The interactions are constructed so that at most two unequal particles can bind to a molecule. Such a system can be interpreted as one where the basic species react to form diatomic molecules, the equilibrium of which at low densities is governed by the well-known law of mass action. Our results explicate and supplement the approach of Andersen to this problem.