Semirigid vibrating rotor target calculation for reaction O(3p)+CH4 →CH3+OH

The time-dependent quantum dynamics calculation for reaction O(3p)+CH4→ CH3+OH is made, using of the semirigid vibrating rotor target (SVRT) model and the time-dependent wave packet (TDWP) method. The corresponding reaction probabilities of different initial states are provided. From the calculation of initial rovibrational state j= 0,v= 0, 1, we can see that the excitation of the H-CH3 stretching vibration gives significant enhancement of reaction probability and the reaction threshold decreases dramatically with the enhancement of the vibrating excitation, which indicates that the vibrating energy of reagent molecules contributes a lot to the molecular collision. As for the calculation of reaction probability of state v= 0, j= 0,1,2,3, the results show that the reaction probability rises significantly with the enhancement of rotational quantum number j while the reaction threshold has no changes. The spatial steric effect of the title reaction is studied and analyzed too after the calculation of reaction probability of states j= 5, k= 0-2, n= 0 and j=5, k=2, n=0-2 is made.     

Sc(Ⅲ)催化硫醇对邻亚甲基苯醌的亲核加成反应合成邻羟基苄硫醚衍生物

以2-[羟基(苯基)甲基]苯酚类化合物和简单的硫醇为原料, 1,2-二氯乙烷为溶剂, 在Sc(Ⅲ)促进下原位生成邻亚甲基苯醌, 并发生亲核加成反应构建邻羟基苄硫醚. 该反应在50 ℃下搅拌2 h即可完成, 目标产物产率82%95%. 反应可放大至克级规模.     

含Laplace-Gauss型混合噪声图像二阶正则化重建方法

假设观测数据含Laplace-Gauss型混合噪声条件下,提出求解数据重建反问题的一种新型一阶二阶混合正则化模型,阐述该模型在断层重建和流体动力学实验定量诊断中的应用.建模过程采用贝叶斯推断理论和期望极大方法,将空间自适应函数引入经典的增广拉格朗日方法得到模型数值算法.所提出的模型及其算法进行图像复原和客体重建实验.结果表明模型算法的可靠性.     

γ射线探测器响应函数的JMCT模拟计算

采用自主研发的JMCT软件,模拟计算了射线在NaI闪烁探测器中的响应函数。JMCT模拟计算了探测过程中所有的、完整的光子-电子耦合输运过程。其模拟计算的射线能量沉积谱、探测器响应函数,与MCNP的计算结果符合得非常好,与Berger解析法计算的结果也基本符合,表明JMCT软件可以在探测器响应函数方面得到满意的结果,JMCT将在实验核物理、核分析技术应用等方面发挥越来越重要的作用。     

水下切伦科夫光光斑的蒙特卡罗模拟

分别采用分出截面法和积累因子法计算了水下放射性源透过一次屏蔽体的中子与射线的剂量场分布,并在这些分布条件下,利用Geant4软件射线在穿越二次屏蔽体后继而穿越后续水层,计算出在3 m水层中产生的切伦科夫(Cherenkov)光通量分布和光谱分布。以纯水为传播介质,在考虑Cherenkov光在不同水层中传播所造成的几何衰减和水层吸收等因素后,由计算获得了Cherenkov光光斑大小和强度分布。     

Semirigid vibrating rotor target calculation for reaction O(~3P)+CH_4 →CH_3+OH

There are some statistical model codes[1—4] as the evaluation tool that have been long and widely used to set up neutron data library below 20 MeV, which is the most important energy region in the application of nuclear engineering. The emitted particles considered in these codes mentioned above are neutrons, protons, as well as the compos-ite particles, such as deuterons, tritons, 3He and alpha particles. These emitted particles and nuclei can be treated as the nucleon or stable clusters. H…     

Influence of ambient pressure on properties and expansion of laser-induced plasma

A Nd:YAG pulsed laser is used to ablate HgCdTe target at different ambient pressures, the emission spectrum is detected by a time- and space-resolved diagnostic technique. It is found that the characteristics of time-resolved emission spectra are influenced by the pressure of background gas. A theoretical model is developed to investigate expansion mechanism of plasma, the time evolution of the propagation distances and the velocities of plasma plume are calculated by the model at pressures of 1.01 × 105, 1000, and 5 Pa,respectively. The calculated results are well consistent with the experimental data.     

TG–MS analysis of thermal behavior and gaseous emissions during co-combustion of straw with municipal sewage sludge

The thermal behavior and gas product distribution during combustion of straw (wheat straw, corn stalks, and cotton stalks), municipal sewage sludge (MSS), and their blends were investigated by thermogravimetry–mass spectroscopy. The experiments were conducted with various blending ratios and temperatures ranging from 323 to 1,173 K. Addition of MSS decreased the combustion performance of the straw. The reactions between wheat straw and corn stalks with MSS proceeded more easily than that of cotton stalks. Significant interactions were observed between the straw and MSS at the char combustion stage. Gaseous species (CO₂, SO₂, NH₃, HCN, and NO) were mainly produced at temperatures of 523–873 K at which most of the mass loss occurred. Higher MSS proportions in the blends resulted in lower emissions peaks for CO₂, NH₃, HCN, and NO except for SO₂. To ensure combustion performance and mitigate problematic gaseous emissions, the proportion of MSS added to the blends should be <30 mass%.     

Quantum dynamics of dissociative adsorption of H2 and D2: The time-dependent wave packet method

A time-dependent quantum wave packet method was used to study the dynamics of dissociative adsorption of H₂ and D₂ on a flat and static surface. The molecule-surface interaction is described using a modified London-Eyring-Polanyi-Sato (LEPS) type potential for the H₂/Ni(100) system. The three-dimensional (3-D) dissociation probabilities were calculated for different initial rovibrational states as a function of initial incident energies. Our results show that the dissociation of the diatomic rotational states whose quantum numbers satisfyj+m = odd is forbidden at low energies for the homonuclear H_z and D₂ due to the selection rule. The effect of the rotational orientation of diatoms on adsorption predicts that the in-plane rotation (m = j) is more favorable for dissociation than the out-of-plane rotation (m = 0). Enhanced dissociation for vibrationally excited molecules and the significant enhancement of the dissociation probability of H2 when compared to D₂ were explained reasonably in terms of quantum mechanical zero-point energies, the tunneling effect and the reflection from an activation barrier. Project supported by the National Natural Science Foundation of China (Grant No. 19694033) and partially by the Science Foundation for Overseas Chinese Scholars and Students, administered by the State Education Commission of China (Grant No. 1992), by the State Key Laboratory of Theoretical and Computational Chemistry of Jilin University at Changchun (Grant No. 98011, and by the Natural Science Foundation of Shandong Province (Grant No. Y96B03022)