高能闪光照相对电子束参数的要求

对高能闪光机光源性能用Monte-Carlo方法模拟研究发现：并非击靶电子束半径越小、发射度越低, 闪光机的照相性能就会越好. 研究结果表明：为了使闪光照相图像视面上照射量分布比较均匀, 对束半径与电子束归一发射度有一个联合限制, 对于20MeV闪光机, 如果击靶电子束有效半径是0.12cm, 那么仅当束归一发射度≥550cm.mrad时,在2°内的照射量不均匀性才小于5%.     

The effect of surface crystalline layers on asymmetric off-diagonal magnetoimpedance in field-annealed CoFeSiB amorphous ribbons

The off-diagonal magnetoimpedance in field-annealed CoFeSiB amorphous ribbons was measured using a pick-up coil wound around the sample. One side of a ribbon was etched in hydrofluoric acid solution during various times in order to change the thickness of the surface crystalline layer appearing after annealing. The asymmetric two-peak field dependence of the off-diagonal impedance was observed for all samples. The evolution of the off-diagonal magnetoimpedance with the change in the ribbon thickness is analyzed.     

Fast Optical Switching Using Oriented Cyanine Dye-Doped Nematic Liquid Crystal

A cyanine dye, 2-[7-（1,3-dihydro-1,3,3-trimethyl-2H-indol-2-ylidene）-1,3,5-heptatrienyl]-1,3,3-trimethyl-3H-indolium iodide （NK-125）, is doped in 4-cyano-4＇-pentylbiphenyl （5 CB）, and the mixture is sandwiched between two pieces of rubbed glass plates. The third-order nonlinear optical properties of the oriented NK-125-SCB layers are measured by the resonant femtosecond degenerate four-wave mixing （DFWM） technique at 760 nm. The third-order nonlinear optical susceptibility of one of the present samples is 5.5×10^-8 esu. The slow DFWM response of the NK-125-SCB layers due to a population grating is accelerated by the increasing laser power because of amplified spontaneous emission （ASE）. On the other hand, we do not observe a similar phenomenon for NK-125- polyethylene glycol （PEG-400）. Oriented NK-125 molecules in nematic liquid crystals must have very high ASE efficiency. Hence the population grating in a DFWM signal disappears within about 4 ps. It is expected that NK-125-SCB can be used as a material for very fast all-optical switching.     

A Relaxation Scheme for Solving the Boltzmann Equation Based on the Chapman-Enskog Expansion

Abstract In [16] a visco-elastic relaxation system, called the relaxed Burnett system, was proposed by Jinand Slemrod as a moment approximation to the Boltzmann equation. The relaxed Burnett system is weaklyparabolic, has a linearly hyperbolic convection part, and is endowed with a generalized eotropy inequality. Itagrees with the solution of the Boltzmann equation up to the Burnett order via the Chapman-Enskog expansion. We develop a one-dimensional non-oscillatory numerical scheme based on the relaxed Burnett system forthe Boltzmann equation. We compare numerical results for stationary shocks based on this relaxation scheme,and those obtained by the DSMC (Direct Simulation Monte Carlo), by the Navier-Stokes equations and bythe extended thermodynamics with thirteen moments (the Grad equations). Our numerical experiments showthat the relaxed Burnett gives more accurate approximations to the shock profiles of the Boltzmann equationobtained by the DSMC, for a range of Mach numbers for hypersonic flows, th     

武器系统生存能力模型分析

对抗过程中，武器系统的生存概率包括以下的四个方面，即：被发现的可能性、被命中的可能性、易毁性和可修理性。武器系统生存能力的动态描述主要划分为四个阶段：被发现阶段、被命中阶段、被毁伤和修复阶段。本文从这四个阶段给出了对抗过程中武器系统生存能力的动态描述，并分析了各个阶段的计算模型。     

Preparation of antimicrobial poly(vinyl alcohol) nanofibers containing silver nanoparticles

Polyvinyl alcohol (PVA) nanofibers containing Ag nanoparticles were prepared by electrospinning PVA/silver nitrate (AgNO₃) aqueous solutions, followed by short heat treatment, and their antimicrobial activity was investigated for wound dressing applications. Since PVA is a water soluble and biocompatible polymer, it is one of the best materials for the preparation of wound dressing nanofibers. After heat treatment at 155 °C for 3 min, the PVA/AgNO₃ nanofibers became insoluble, while the Ag⁺ ions therein were reduced so as to produce a large number of Ag nanoparticles situated preferentially on their surface. The residual Ag⁺ ions were reduced by subsequent UV irradiation for 3 h. The average diameter of the Ag nanoparticles after the heat treatment was 5.9 nm and this value increased slightly to 6.3 nm after UV irradiation. It was found that most of the Ag⁺ ions were reduced by the simple heat treatment. The PVA nanofibers containing Ag nanoparticles showed very strong antimicrobial activity. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 2468–2474, 2006     

标的股价服从混合过程的期权定价公式及有限元算法

本文将马尔科夫跳跃过程叠加于 Ito过程 ,形成混合过程 ,并用该过程来刻画股价走势情况。而后在标的股价服从混合过程的基础上 ,推导出了欧式看涨期权的定价公式 ,并对美式看跌期权定价给出了有限元算法。     

Effects of Processing Parameters on Microstructure and Properties of Nanoscale ZrC/ZrB2 Multilayered Coatings

ZrC/ZrB2 multilayered coatings with bilayer periods of 3.5-40nm are synthesized by rf magnetron sputtering. Analyses of x-ray diffraction, scanning electron microscopy and nanoindentation indicate that multilayered coatings possess much higher hardness and greater fracture resistance than monolithic ZrC and ZrB2 coatings. A maximum hardness （41.TCPa） and a critical fracture load （73.7mN） are observed in the multilayer with A = 32 nm deposited at the substrate bias -40 V. Higher residual stress built in the ZrC layer can be released by periodic insertion of ZrB2 into the ZrC layer. A clear multilayered structure with mixed ZrB2（001）, ZrB2 （002） and ZrC （111） orientations should be responsible for the enhanced mechanical properties.     

Crystal and Molecular Structure of OMPCTF

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