加恒定轴向磁场螺旋型波荡器中的单电子轨道分析

研究了在包含恒定轴向磁场的螺旋型波荡器中运动的电子动力学行为.采用Mathematica数值模拟考察一般条件下的电子轨道及其在横向平面内的投影形状.在电子入射偏离理想螺旋型轨道的情况下,电子在波荡器中的运动轨道在横向平面内的投影曲线可能是周期或者准周期的,对此作了讨论并给出了相应的判据.     

硅胶破碎法抽提真菌染色体DNA

在进行基因组步行PCR克隆真菌木聚糖酶基因的研究中,探索并建立了一套可在普通分子生物学实验室采用的高得率、高质量真菌染色体DNA的抽提方法.采用液氮研磨和硅胶破碎相结合提高染色体DNA得率,采用亚精胺法纯化提高DNA的纯度.抽提的染色体DNA用琼脂糖凝胶电泳、限制酶切、PCR反应及紫外吸收光谱等方法进行了鉴定,结果显示此方法可以获得分子量大、样品纯的染色体DNA,可有效地用于PCR扩增,并能被限制酶有效地消化.     

A Concise Method to Predict the Mean Dynamic Pressure on a Plunge Pool Slab

Hydrodynamic pressure exerted on a plunge pool slab by jet impingement is of high interest in high dam projects. The present study experimentally investigated the characteristics of pressure induced by a jet through a constant width flip bucket (CFB) and a slit flip bucket (SFB). A pressurized plane pipe was employed in the flume experiments to control the inlet velocities in the flip buckets. A concise method is proposed to predict the mean dynamic pressure field. Its implementation is summarized as follows: First, the position of the pressure field is determined by the trajectories of free jets, and to calculate its trajectories, an equation based on parabolic trajectory theory is used; second, the maximum mean dynamic pressure is obtained through dimensional analysis, and then the pressure field is established by applying the law of Gaussian distribution. Those steps are integrated into a concise computing procedure by using some easy-to-obtain parameters. Some key parameters, such as takeoff velocity coefficient, takeoff angle coefficient, and the parameter k2, are also investigated in this paper. The formulas of these coefficients are obtained by fitting the experimental data. Using the proposed method, the easy-to-obtain geometric parameters and initial hydraulic conditions can be used to calculate the maximum mean dynamic pressure on the slab. A comparison between experimental data and calculated results confirmed the practicability of this model. These research results provide a reference for hydraulic applications.     

How a moving passive observer can perceive its environment ? The Unruh effect revisited

We consider a point-like observer that moves in a medium illuminated by noise sources with Lorentz-invariant spectrum. We show that the autocorrelation function of the signal recorded by the observer allows it to perceive its environment. More precisely, we consider an observer with constant acceleration (along a Rindler trajectory) and we exploit the recent work on the emergence of the Green’s function from the cross correlation of signals transmitted by noise sources. First we recover the result that the signal recorded by the observer has a constant Wigner transform, i.e. a constant local spectrum, when the medium is homogeneous (this is the classical analogue of the Unruh effect). We complete that result by showing that the Rindler trajectory is the only straight-line trajectory that satisfies this property. We also show that, in the presence of an obstacle in the form of an infinite perfect mirror, the Wigner transform is perturbed when the observer comes into the neighborhood of the obstacle. The perturbation makes it possible for the observer to determine its position relative to the obstacle once the entire trajectory has been traversed.     

基于加权流量介数中心性的路网脆弱性分析——以无锡市为例

针对当前路网脆弱性研究中缺乏对真实交通状况考量的问题,在复杂网络理论的基础上,结合交通流量信息,提出了基于加权流量介数中心性的路网脆弱性分析方法。首先计算路网拓扑抽象图中各节点的最短路径介数中心性,然后使用流量数据对相应区域最短路径介数中心性加权,综合得到最终的脆弱性指标结果。以无锡市为例,对其实际交通路网脆弱性进行了计算,结果表明,该方法能综合反映静态全局路网结构与动态局部通行信息和现实交通情景下的路网脆弱性。     

颗粒流体两相流模型研究进展

本文介绍了颗粒流体两相流动的特征及其模拟方法, 重点论述了拟流体模型的研究现状及发展, 并对两相流动模拟中的各种方法进行了展望。     

H+CN体系中平行络合反应的动力学

利用分子反应动力学的经典轨迹法研究化学反应体系已经开展了很多工作,但是,研究长寿命络合物的几何异构体就显得有些困难,主要表现在该方法对几何异构体不容易判别．由于这些原因和计算机时大增,Davis[1]利用经典轨迹法和统计方法相结合,研究了H＋CN和H＋NC体系在固定方位时的长寿命络合物动力学行为,并且采用Murrel等[2]拟合光谱数据的势能函数,该势能函数在HCN和HNC平衡点的频率与实验值相差较大．本文利用经典轨迹法研究了H＋CN产生HCN和HNC平行络合物异构体的分子反应动力学行为,揭示了平行络合反应产生几何异构体的…     

Flow properties of a dusty-gas point source in a supersonic free stream

By using Lagrangian method, the flow properties of a dusty-gas point source in a supersonic free stream were studied and the particle parameters in the near-symmetry-axis region were obtained . It is demonstrated that fairly inertial particles travel along oscillating and intersecting trajectories between the bow and termination shock waves . In this region, formation of " mufti- layer structure" in panicle distribution with alternating low- and high density layers is revealed. Moreover, sharp accumulation of particles occurs near the envelopes of particle trajectories .     

双原子分子在啁啾激光作用下的经典解离

采用辛算法及经典理论方法,计算了HF分子在啁啾激光作用下的经典解离,讨论了解离几率随激光强度的变化,以及在相同激光强度下,选取不同的振动态作为初始态时解离几率的变化.     

Ba原子与溴代烷烃反应产物转动取向的动力学研究

本文应用准三体模型及扩展的LEPS势能面 (PES)、准经典轨线和CPOAM模型计算了Ba+RBr(R=CH3,C2H5,C3J7,C4H9,n-C5H11)→BaBr+R反应体系产物 BaBr的转动取向,结果表明产物BaBr的转动取向随碰撞能的增加越趋强烈,随烷基的增大而减弱.