新型复合物Li…HF,Li…FH,Li…H2O和Li…NH3的一阶超极化率的从头算理论研究

在MP2/6-311 G(2df,2pd)水平上优化得到了几种小型碱金属—极性分子复合物的结构,利用有限场方法[HF,MP2,MP3,MP4(SDQ)]在15种基组上分别计算了它们的偶极矩(μ),极化率(α0),各向异性极化率(Δα)和一阶超极化率(β0).在MP4(SDQ)/6-311 G(2df,2pd)理论水平上,各复合物分子一阶超极化率分别为:Li…HF,β0=3957.575 a.u.;Li…FH,β0=12939.614 a.u.;Li…NH3,β0=34881.899a.u.;Li…H2O,β0=39820.410 a.u..而分子HF,NH3,H2O的一阶超极化率的值分别为1.224 a.u.,35.560 a.u.,20.130 a.u..结果表明,复合物分子中的额外电子对分子非线性光学性质有巨大的贡献.     

Corrosion resistance of cerium-based conversion coatings on alumina borate whisker reinforced AA6061 composite

Cerium-based conversion coatings on Al₁₈B₄O₃₃w/6061Al composite surface were obtained by immersing the composite into a solution containing various concentrations of CeCl₃. Results indicate that the susceptibility to pitting for the conversion-coated composites was much lower than that of the untreated composite, and the corrosion resistance of the coated composites was improved markedly; moreover, the concentration of CeCl₃ in the cerium solution affects significantly the corrosion behaviors of the coated composites. The coating obtained from a solution containing 7.5 g CeCl₃ into 1000 ml produced better corrosion resistance on the composite due to the surface being almost covered by conversion coating. EDX and XPS experimental results indicated that the coatings were made up of oxygen, cerium, and aluminum.     

Source function extracted from single-event HBT correlation functions of hydrodynamical sources

We investigate the single-event two-pion correlation functions for the hydrodynamic particle-emitting sources with the fluctuating initial conditions generated by the Heavy Ion Jet Interaction Generator （HIJING）. Using a three-dimension fast Fourier transform （FFT）, we further extract the source functions from the single-event correlation functions. It is found that the inhomogeneity of the hydrodynamic sources with the fluctuating initial conditions lead to event-by-event fluctuations of the correlation functions and source functions.     

Interferometry Signatures for QCD First-Order Phase Transition in High Energy Heavy Ion Collisions

Using the technique of quantum transport of the interfering pair we examine the Hanbury-Brown-Twiss （HBT） interferometry signatures for the particle-emitting sources of pions and kaons produced in heavy ion collisions at 10-30 AGeV. The evolution of the sources is described by relativistic hydrodynamics with the first-order phase transition from quark-gluon plasma （QGP） to hadronic matter. We use quantum probability amplitudes in a path-integral formalism to calculate the two-particle correlation functions, where the effects of particle decay and multiple scattering are taken into consideration. Our model-calculated results indicate that both the HBT radii of pions and kaons increase with the system initial energy density. The HBT lifetimes of the pion and kaon sources increase significantly when the initial energy density is tuned to the phase boundary between the QGP and mixed phase. This increase of HBT lifetimes will likely appear in heavy ion collisions with an incident energy between 10-30 AGeV.     

载钯TiO2半导体悬浮催化体系中CO2的光还原

在半导体光催化还原CO₂的反应过程中,一般都伴有氢气的产生^[1,2].为了提高CO₂还原产物的收率,必须设法抑制析氢过程。在催化剂表面担载某种吸氢物质是抑制氢气产生的有效方法之一。理想的吸氢物质不仅能吸附氢,且被其吸附的氢还具有还原CO₂的能力。     

基于并行组合加权均值级联形态滤波算法的散斑噪音压缩

本文提出一种新的用于散斑噪音压缩的并行组合加权均值级联形态滤波算法。首先采用3×1和1×3两个线型结构元素分别进行形态开一闭、闭一开运算,然后利用散斑噪音的负指数统计规律加权求平均,最后再采用5×1和1×5两个线型结构元素重复上述运算。模拟结果表明此算法既有效地压缩了散斑噪音又保持了图象的几何结构,并且通过比较证明其优于F.Safa的多方向形态滤波算法。