Investigation into the rotational bands of ~(185)Pt with the particle-rotor model

Theoretical calculations have been performed for the ν9/2+[624](i13/2) and ν7/2-[503](f7/2) bands of 185Pt in the framework of particle-rotor model. The band properties of signature splitting and configuration mixing have been analyzed. The level energy and signature splitting before the band crossing can be well interpreted by introducing triaxiality. The positive-parity yrast band is pro posed to be dominated by the ν9/2+[624](i13/2) component, while the negative-parity band shows strong mixing of ν7/2-[5...     

Estimates for correlations in billiards with large arcs

Bunimovich billiards are ergodic and mixing. However, if the billiard table contains very large arcs on its boundary then if there exist trajectories experience infinitely many collisions in the vicinity of periodic trajectories on the large arc. The hyperbolicity is nonuniform and the mixing rate is very slow. The corresponding dynamics are intermittent between regular and chaotic, which makes them particularly interesting in physical studies. The study of mixing rates in intermittent chaotic systems is mo...     

Prediction of thermodynamic and surface properties of Pb−Hg liquid alloys at different temperatures

The thermodynamic properties, such as free energy of mixing, heat of mixing, activity and structural properties, such as concentration fluctuation in long wavelength limit, short-range order parameter of Pb–Hg liquid alloy at 600 K have been calculated using theoretical modelling. It has then been correlated with modified Butler model to compute the surface tension of the alloys at different temperatures. The Pb–Hg system at 600 K is found to be ordering at higher concentration of Pb.     

Mixing of the Glauber dynamics for the ferromagnetic Potts model

We present several results on the mixing time of the Glauber dynamics for sampling from the Gibbs distribution in the ferromagnetic Potts model. At a fixed temperature and interaction strength, we study the interplay between the maximum degree (Δ) of the underlying graph and the number of colours or spins (q) in determining whether the dynamics mixes rapidly or not. We find a lower bound L on the number of colours such that Glauber dynamics is rapidly mixing if at least L colours are used. We give a closely‐matching upper bound U on the number of colours such that with probability that tends to 1, the Glauber dynamics mixes slowly on random Δ‐regular graphs when at most U colours are used. We show that our bounds can be improved if we restrict attention to certain types of graphs of maximum degree Δ, e.g. toroidal grids for Δ = 4. © 2014 Wiley Periodicals, Inc. Random Struct. Alg., 48, 21–52, 2016     

大跨越管道油气混输压力波速及响应特性研究

基于双流体模型,利用小扰动理论,提出了油气混输大跨越管道压力波速模型.利用计算机编程对其求解,通过大跨越管道油气混输实例,得到了以下结论:压力波速的变化受气相影响较大,即使少量气体也能在较大程度上影响压力波速,随混输气量增大,压力波速减小,压力响应时间延长;混输低点气体所承受的压力较混输高点大,从而低点处气相压缩系数小,混输低点较混输高点压力波速增大,压力响应时间相应缩短;在输运管道低点处,气体受到极大压缩,压力波速的变化不明显,几乎收敛于恒定值,在混输管道高点处压力波速变化剧烈.     

信息化时代物理化学课程的教学改革与实践

互联网的发展加速了信息和知识的传播,在为大学课程教学提供更多资源的同时也给传统的课堂教学方法带来很大挑战。介绍了北京师范大学物理化学教学团队在线上线下混合教学方法的创立、大规模在线开放课程(MOOC)建设、思政元素引入教学等方面利用互联网资源所实施的教学改革和实践,为探究和建立信息时代大学化学课程教学方法的新模式提供参考。     

High-efficiency absorption of low NOX concentration in metallurgical flue gas using a three dimensional printed large-flow microstructured reactor

In the process of nitric acid dissolving precious metals, a large amount of NOx exhaust gas will be produced. This research aims at the development of a new method for the removal of low-concentration nitrogen oxides from metallurgical flue gas. In this process, a printed three-dimensional large-flow microstructure reactor and urea solution are used for the removal of NOx, which facilitates the greater efficiency of denitrification(≥94%). Urea plays an important role in the redox of NO₂, such as NO₂ is reduced to N₂ in solution. Both the gas and the liquid phase simultaneously react in the microchannels of the microfluidic reactor. The channels allow the proper mixing of urea and NaClO₂ during the flow which efficiently removes NO_x at low concentrations. The optimum condition for high denitration efficiency is outlined: the urea solution with 3%,temperature of the mixed solution is 293.15 K, gas–liquid flow mass ratio is 1:1, pH value (8.0–10.0), C_NaClO2 = 0.02 mol/L. This work successfully describes the use of a microfluidic reactor to enhance and maintain the denitration efficiency. This work describes how to successfully enhance and maintain the denitration efficiency while using a printed three-dimensional large-flow microstructure reactor.     

计算化学在分子轨道教学中的应用

分子轨道理论是理解分子电子结构与微观性质的重要理论之一,也是本科生与研究生结构化学教学中的重点与难点。学生对原子轨道组合形成分子轨道、分子轨道能级交叉混合等知识的理解缺乏形象直观、定量的认识。本文通过基于量子化学或密度泛函理论的Gaussian 03计算软件,计算、绘制并分析了F_2、O_2、N_2、HF、CO等的分子轨道能级图,将学生较难理解的内容定量、直观地呈现出来,形象地解释了分子轨道成键原则与电子填充原则等分子轨道理论中的重难点,加深了学生对分子轨道理论的理解,特别是sp轨道混杂导致的σ_(2p_z)与π_(2p)轨道能级交叉这一难点,激发了学生学习的主动性和积极性,提高了教学质量。在此基础上,利用分子轨道理论分析了CO_2的电子结构,使学生学会应用分子轨道理论解决实际问题,巩固了相关课堂理论知识。     

Material Discrimination in Nanoparticle Hetero-Aggregates by Analysis of Scanning Transmission Electron Microscopy Images

Hetero-contacts are interfaces between different materials at the nanoscale leading to novel functional properties. In hetero-aggregates, primary particles of at least two different materials are mixed at primary particle or cluster level. Double flame spray pyrolysis (DFSP) is a versatile technique for the controlled synthesis of such materials. Characterization of hetero-aggregates by scanning transmission electron microscopy (STEM) requires acquisition and evaluation of many aggregate images in order to derive statistically significant results. Usually, STEM energy dispersive X-ray spectroscopy (EDXS) is used to acquire elemental maps providing the material distribution of the primary particles within hetero-aggregates. However, the acquisition of a single EDXS map takes up to several minutes. For this reason, determination of material types of primary particles from the intensity in high-angle annular dark field STEM images alone is desirable. These images can be acquired within a couple of seconds. In the present work, a method is suggested which allows for achieving this objective. It can be applied to distinguish materials with a significant difference in their atomic number and hence sufficient material contrast in the STEM images.