高温辐射场作用下的原子过程

等离子体中辐射能量密度与物质能量密度的比值是区分等离子体原子过程性质的重要参量. 根据这个参量, 等离子体中的原子过程可分为碰撞占优和辐射占优两种典型类型. 数值模拟发现碰撞占优和辐射占优的原子过程有不同的性质: 碰撞占优的等离子体能够很快达到LTE状态; 辐射占优等离子体的束缚电子温度、电离度和自由电子温度存在不同的弛豫时间尺度, 存在某种形式的准平衡状态.     

Irreversibility of a quantum walk induced by controllable decoherence employing random unitary operations

Quantum walk is different from random walk in reversibility and interference. Observation of the reduced re- versibility in a realistic quantum walk is of scientific interest in understanding the unique quantum behavior. We propose an idea to experimentally investigate the decoherence-induced irreversibility of quantum walks with trapped ions in phase space via the average fidelity decay. By introducing two controllable decoherence sources, i.e., the phase damping channel (i.e., dephasing) and the high temperature amplitude reservoir (i.e., dissipation), in the intervals between the steps of quantum walk, we find that the high temperature amplitude reservoir shows more detrimental effects than the phase damping channel on quantum walks. Our study also shows that the average fidelity decay works better than the position variance for characterizing the transition from quantum walks to random walk. Experimental feasibility to monitor the irreversibility is justified using currently available techniques.     

Stochastic optimization of an urban rail timetable under time‐dependent and uncertain demand

Urban rail planning is extremely complex, mainly because it is a decision problem under different uncertainties. In practice, travel demand is generally uncertain, and therefore, the timetabling decisions must be based on accurate estimation. This research addresses the optimization of train timetable at public transit terminals of an urban rail in a stochastic setting. To cope with stochastic fluctuation of arrival rates, a two‐stage stochastic programming model is developed. The objective is to construct a daily train schedule that minimizes the expected waiting time of passengers. Due to the high computational cost of evaluating the expected value objective, the sample average approximation method is applied. The method provided statistical estimations of the optimality gap as well as lower and upper bounds and the associated confidence intervals. Numerical experiments are performed to evaluate the performance of the proposed model and the solution method.     

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引进了美国GAMMA公司的高精度数字式可调标准光源RS-5B,并对其性能参数进行了测试。结果表明,该光源光强空间分布非常稳定,在光强大于0.001μW•cm-2时,复位性优于1%;在光强大于0.01μW•cm-2时,稳定性优于0.5%。其输出光强与标称值呈线性分布关系。这些优良的参数和特性满足聚变物理标定研究中对标定源的需求,为物理实验数据分析和计算模拟提供了条件。     

Stability in terms of two measures of solutions to stochastic partial differential delay equations with switching

In this paper, the problem of stability in terms of two measures is considered for a class of stochastic partial differential delay equations with switching. Sufficient conditions for stability in terms of two measures are obtained based on the technique of constructing a proper approximating strong solution system and conducting a limiting type of argument to pass on stability of strong solutions to mild ones. In particular, the stochastic stability under the fixed‐index sequence monotonicity condition and under the average dwell‐time switching are considered.     

N‐dimensional switch function for energy conservation in multiprocess reaction dynamics

The MReaDy program was designed for studying Multiprocess Reactive Dynamic systems, that is, complex chemical systems involving different and concurrent reactions. It builds a global potential energy surface integrating a variety of potential energy surfaces, each one of them representing an elementary reaction expected to play a role in the chemical process. For each elementary reaction, energy continuity problems may happen in the transition between potential energy surfaces due to differences in the functional form for each of the fragments, especially if built by different authors. A N‐dimensional switch function is introduced in MReaDy in order to overcome such a problem. As an example, results of a collision trajectory calculation for H₂ + OH → H₃O are presented, showing smooth transition in the potential energy, leading to conservation in the total energy. Calculations for a hydrogen combustion system from 1000 K up to 4000 K shows a variation of 0.012% when compared to the total energy of the system. © 2016 Wiley Periodicals, Inc.     

价电子平均能级连接性指数及其应用

定义价电子平均能级（δi）为：δi=(ni-1)(ni+ΣEij)0.5/(1+mi)。由δi建构分子连接性指数（mQ）,其中,0Q=Σ(δi)-0.5、1Q=Σ(δiδj)-0.5。0Q与无机物总键能ΔE、0Q2与过渡元素卤化物的ΔfHmθ、1Q0.5与碱金属卤化物晶格能U、0Q及1Q与无机氢化物pKa的相关系数分别为0.9734、0.9769、0.9906、0.9945,均优于文献方法。mQ是一种结构选择性、性质相关性俱佳的拓扑指数。     

不饱和类卡宾H_2C=CLiF的结构及氢迁移反应的DFT研究

用量子化学中的密度泛函DFT方法,在B3LYP/6-311G~*水平上研究了不饱和类 卡宾H_2C=CLiF的结构。结果表明,只有1种平衡结构是稳定的。对稳定的平衡结构 ,找到了分子内氢迁移反应的过渡态,并计算了不同温度下不饱和类卡宾 H_2C=CLiF的平均寿命τ,在200 K时,τ = 7.9 d,在300 K仅为τ = 2.4 s。     

Densities and isothermal compressibilities of ionic liquids—Modeling and application

Two corresponding-states forms have been developed for direct correlation function integrals in liquids to represent pressure effects on the volume of ionic liquids over wide ranges of temperature and pressure. The correlations can be analytically integrated from a chosen reference density to provide a full equation of state for ionic liquids over reduced densities from 1.5 to more than 3.6. One approach is empirical with 3 parameters, the other is a 2-parameter theoretical form which is directly connected to a method for predicting gas solubilities in ionic liquids. Parameters for both methods have been obtained for 28 different ionic liquid systems by reduction of carefully validated PρT data. The results show excellent agreement with the experimental data for nearly all substances over all ranges of conditions. Group contributions to parameters are also explored, leading to an entirely predictive method for ambient pressure densities and densities of compressed ionic liquids. Extensive comparisons are made with other techniques.     

KINETIC ANALYSIS OF CO-CONDENSATION POLYMERIZATION OF AB2 AND AB MONOMERS

This work deals with the kinetics of co-condensation polymerization of AB2 and AB monomers, giving expressions of the two-dimensional molecular weight distribution function and the number/weight average molecular weights of the resulting copolymers. The two-dimensional molecular weight distribution depends on two indices, n and l, which are the respective numbers of AB2 and AB units in a copolymer species. The evolution of the two-dimensional weight and z distributions during the co-condensation polymerization has been evaluated systematically. Finally, the two-dimensional distribution was transformed into a one-dimensional molecular weight distribution with only one variable (the molecular weight of the products instead of the degree of polymerization). The calculated results show that the highly branched copolymer has a very broad molecular weight distribution when the co-condensation polymerization approaches completion.