Chemical bond model of lattice distortions in hexagonal layers

The lattice distortions of a hexagonal layer are discussed in terms of a simple model with isotropic interactions. If only nearest-neighbour interactions are considered, the only stable distorted structures are the MnP structure (with zig-zag chains) and the low-temperature NbS structure (with triangles of metal atoms). If also interactions with more distant atoms are considered, more complicated distortions, as observed in crystals with charge density waves, are possible.     

过渡金属原子掺杂的锯齿型磷烯纳米带的磁电子学特性

利用基于密度泛函理论的第一性原理方法,研究了掺杂铁、钴和镍原子的锯齿型磷烯纳米带(ZPNR)的磁电子学特性.研究表明,掺杂和未掺杂ZPNR的结构都是稳定的.当处于非磁态时,未掺杂和掺杂钴原子的ZPNR为半导体,而掺杂铁或者镍原子的ZPNR为金属.自旋极化计算表明,未掺杂和掺杂钴原子的ZPNR无磁性,而掺杂铁或者镍原子的ZPNR有磁性,但只能表现出铁磁性.处于铁磁态时,掺杂铁原子的ZPNR为磁性半导体,而掺杂镍原子的ZPNR为磁性半金属.掺杂铁或者镍原子的ZPNR的磁性主要由杂质原子贡献,产生磁性的原因则是在ZPNR中存在未配对电子.掺杂位置对ZPNR的磁电子学特性有一定的影响.该研究对于发展基于磷烯纳米带的纳米电子器件具有重要意义.     

类锂离子2s2p2p^2S三激发态的能量和宽度

采用马鞍点变分方法和复数转动技术，计算了类锂离子２ｓ２ｐ２ｐ２Ｓ三激发共振态的能量，并运用截断变分方法得到能量改进量，以及计算了相对论效应、质量极化效应，从而获得了高精度的能量计算值。还计算了该系统的Ａｕｇｅｒ宽度，位移和辐射跃迁率。     

低压下飞秒激光诱导Cu等离子体的诊断及空间分布实验研究

本文分别利用Gauss、Lorentz和Voigt函数对10Pa背景气压下飞秒激光诱导Cu等离子体光谱进行了拟合分析,结果表明,光谱在150ns内与Lorentz线型符合较好,200ns后与Gauss线型符合较好,Voigt线型与实验谱线一直符合较好。本文还对等离子体的电子密度和温度进行了诊断,并给出了它们随时间的演化;由发射光谱强度的时空演化,推知了等离子体的空间分布;利用时间飞行谱(TOF)得出了等离子体初期沿垂直靶面的膨胀速度。     

HL-1M装置撕裂模不稳定性的相位比对法研究

采用相位比对法模拟分析了HL-1M装置的磁扰动模式,模拟结果同预期的一致。在具有撕裂模不稳定性的典型放电中,探测到独立模m=2、3、4,耦合模m=2、3,并与用空间傅立叶分析方法得到的扰动模式的分析结果进行了比较。讨论了这些方法在实验分析中的可行性和有效性。     

Noether symmetry and conserved quantity for a Hamilton system with time delay

In this paper, the Noether symmetries and the conserved quantities for a Hamilton system with time delay are discussed. Firstly, the variational principles with time delay for the Hamilton system are given, and the Hamilton canonical equations with time delay are established. Secondly, according to the invariance of the function under the infinitesimal transformations of the group, the basic formulas for the variational of the Hamilton action with time delay are discussed,the definitions and the criteria of the Noether symmetric transformations and quasi-symmetric transformations with time delay are obtained, and the relationship between the Noether symmetry and the conserved quantity with time delay is studied. In addition, examples are given to illustrate the application of the results.     

锥头弹丸穿透薄钢板的实验研究

 为了研究延性薄靶的穿透性能,进行了90°锥头弹丸穿透薄钢板的准静态和动态实验。通过准静态实验,得到了4种不同厚度钢板的载荷-压入位移曲线及破坏模式;结合膜力理论模型及纯弯静塑性破坏模型,对实验结果进行了分析,得出：对于薄靶,大变形膜力起主导作用,随着靶厚增加,弯距在板整体变形过程中的影响逐渐增大。通过动态穿透实验,得到了弹丸穿透4种不同厚度钢板的入射速度、残余速度及靶板破坏模式,计算得到穿透耗能。最后,将准静态实验与动态实验结果进行了对比讨论。     

Quantum Maps with Memory from Generalized Lindblad Equation

In this paper, we proposed the exactly solvable model of non-Markovian dynamics of open quantum systems. This model describes open quantum systems with memory and periodic sequence of kicks by environment. To describe these systems, the Lindblad equation for quantum observable is generalized by taking into account power-law fading memory. Dynamics of open quantum systems with power-law memory are considered. The proposed generalized Lindblad equations describe non-Markovian quantum dynamics. The quantum dynamics with power-law memory are described by using integrations and differentiation of non-integer orders, as well as fractional calculus. An example of a quantum oscillator with linear friction and power-law memory is considered. In this paper, discrete-time quantum maps with memory, which are derived from generalized Lindblad equations without any approximations, are suggested. These maps exactly correspond to the generalized Lindblad equations, which are fractional differential equations with the Caputo derivatives of non-integer orders and periodic sequence of kicks that are represented by the Dirac delta-functions. The solution of these equations for coordinates and momenta are derived. The solutions of the generalized Lindblad equations for coordinate and momentum operators are obtained for open quantum systems with memory and kicks. Using these solutions, linear and nonlinear quantum discrete-time maps are derived.     

超音速子母弹开舱后流场特性研究

用数值求解雷诺平均N-S方程的方法对超音速子母弹开舱后复杂外形的流场特性进行数值模拟.模拟结果与试验结果对比表明,采用S-A一方程湍流模型求解雷诺平均N-S方程,并以AUSM+作为离散格式的数值方法,可较细致地模拟开舱后弹体周围的定常绕流特性.对有攻角时流场结构进行分析,并对其流动机理进行探讨.发现开舱后在弹肩处的后向台阶有回流形成,横截面子弹弹体表面边界层分离使装配空隙内形成涡流并使弹体环向表面压力出现极小峰值,不规则的外形使尾流不对称.可为确定子弹抛撒初始条件提供参考.     

Measurement and simulation of partially-premixed cellular tubular flames

Experimental and numerical simulation results are reported of partially-premixed cellular tubular flames. Parametric measurements across stretch rate and equivalence ratio are taken by chemiluminescent imaging and are presented for the first time. Select hybrid cases with both cellular and non-cellular flame structures are examined with laser-induced spontaneous Raman scattering. Results are spatially resolved in two dimensions and radial interpolations of reaction and extinction zones are compared to numerical simulations using multicomponent transport and detailed chemical kinetics. Experimental cell structures and extinction zones are well predicted by numerical simulation, with discrepancies of temperature and H₂O and temperature primarily observed in locations with moderate and high mole fractions of CO₂. A novel cellular structure, denoted as a “split-cell” flame, is reported for the first time with both chemiluminescent imaging and Raman scattering. Results indicate that partially-premixed flames are valuable as experimental and numerical benchmarks to advance fundamental combustion research.     

Prediction method for listening score and psychological impression taking into account hearing loss due to factors such as aging

This paper considers how the listening scores obtained for audio signals and psychological impressions for speech audibility change when factors such as hearing loss due to aging are taken into account. Concretely, frequency filters for simulating hearing loss due to factors such as aging are first prepared. Next, psychological listening experiments are conducted in which both the audio signal and the noise passing through the above-mentioned filters are transmitted to subjects with normal hearing. Using the observed experimental data, the relationships between the weighted-mean spectral distance and the listening scores of the audio signals and psychological impressions with respect to speech audibility are investigated. Next, based on these relationships, problems associated with the prediction of listening scores of audio signals and psychological impressions with respect to speech audibility are discussed. The predicted results are in good agreement with the observed values.     

忆阻电路的基本性质及其应用

对有边界的忆阻元件与电容、 电感的串、 并联电路分别进行了研究, 分析了电路所具有的特性和频率及元件的电容、 电感对电路的影响, 通过仿真验证了理论结果.根据有边界的忆阻元件及其构成电路的性质研究, 对其潜在的应用进行了预测.     

Triaxial Shape,Signature Splitting,and Shape Coexistence in 127,129,131Nd

Signature splitting and shape coexistence at high spin in the neutron deficient nucleus ¹²⁹Nd are investigated with the configuration-dependent cranked Nilsson-Strutinsky approach. The calculated bands are compared with the observed signature partner bands and very good agreement results at high spin are obtained. The observed deformed bands are confirmed as normal and highly deformed and their properties are explained theoretically. Terminating states in ¹²⁹Nd and other terminations are predicted. There is shape coexistence within the same configuration from low-spin states to high-spin states. Possible normal and highly deformed bands with rotation around the intermediate principal axis in several interesting configurations of ¹²⁹Nd are discussed. The experimental results for ¹³¹Nd are simply discussed and the calculated bands are in good agreement with observed bands at high spin. Triaxial shapes in ¹²⁷Nd with a triaxial deformation of γ～-12^º are predicted and should be observed experimentally. The value of negative γ of π(h_11/2)⁴ν(h_11/2)⁷ configuration increases with neutron number increasing in ^127,129,131Nd. The triaxial shape evolutions with neutron number increasing in ^127,129,131Nd and in ^{126,128,130,132}Pr are explained by the strong driving force of specified single particle orbitals towards to triaxial shape.     

Feasibility of controlling speed-dependent low-frequency brake vibration amplification by modulating actuation pressure

In this article, a feasibility study of controlling the low frequency torque response of a disc brake system with modulated actuation pressure (in the open loop mode) is conducted. First, a quasi-linear model of the torsional system is introduced, and analytical solutions are proposed to incorporate the modulation effect. Tractable expressions for three different modulation schemes are obtained, and conditions that would lead to a reduction in the oscillatory amplitudes are identified. Second, these conditions are evaluated with a numerical model of the torsional system with clearance nonlinearity, and analytical solutions are verified in terms of the trends observed. Finally, a laboratory experiment with a solenoid valve is built to modulate actuation pressure with a constant duty cycle, and time–frequency domain data are acquired. Measurements are utilized to assess analytical observations, and all methods show that the speed-dependent brake torque amplitudes can be altered with an appropriate modulation of actuation pressure.     

Nuclear vibrations and rotations of like nucleons in the same shell in even-even nuclei

The vibrational and rotational motions in even nuclei are considered. A microscopic study of these motions leads to a relation between the vibrational motion in spherical nuclei and the rotational motion in deformed nuclei. Nuclei with like nucleons in the same shell are considered. The quadrupole two-body interactions are used in the large singlej-shell of even nuclei. The energies and transition operators of nuclei in the nuclear rotational region are calculated using this microscopic method. Quadrupole moments are also calculated. These calculations are compared with the rotational model of the aligned coupling scheme. The present calculations are in good agreement with previous calculations.     

Experiments on Ion-Acoustic Solitons in Plasmas Invited Review Article

Experiments on ion-acoustic solitons are reviewed. Theories and numerical simulations which are relevant to experimental results are also presented. The measured velocity and width of planar solitons are compared with the predictions of the Korteweg-deVries (KdV) equation which includes a finite ion temperature. The spatial evolution of compressive or rarefactive pulses is discussed. Cylindrical and spherical solitons are introduced together with a modified KdV equation and numerical results. Oblique collisions and their evolution, including overtaking and head-on collisions of two planar, cylindrical, or spherical solitons are described. Reflection, diffraction, and other topics related with ion-acoustic solitons are presented.     

Intensity,correlations, and linewidths of two mode lasers with intensity coupling near threshold

Two mode lasers with intensity coupling are treated by simple fluctuation theory. The intensities of the two modes as functions of pump power are calculated together with the correlation matrix. Equations of motion for the intensities are derived from which the decay times of correlations are found by a method of quasilinearization as well as by decoupling the hierarchy of correlation functions. Details of photon fluctuation linewidths are reported together with the time dependent correlations between different modes.     

激光烧蚀RT不稳定性线性增长率和非线性行为的数值研究

 给出了不同情况下多种波长的烧蚀瑞利 泰勒不稳定性线性增长率的二维计算结果，并与Takabe公式和Sanz公式进行了比较，最后给出了单模激光烧蚀RTI非线性发展行为的数值结果。线性增长率的二维计算结果很好验证了Sanz公式，表明β值应是2，不是3。当烧蚀速度较大或烧蚀面较宽时，用Takabe公式估计的烧蚀RTI线性增长率与二维计算值明显不符。     

Group structure analysis for classical lattice systems with constraints: I. General properties

The group structure associated with lattice systems without constraints is extended to systems with constraints and some of its physical consequences are investigated. In particular low- and high-temperature expansions, equilibrium equations and duality transformations are analyzed within this framework. It is shown that a large class of systems with constraints whose configuration space has a group structure are “equivalent” to systems without constraints. These structures are illustrated with several examples.     

Particle-number conserving analysis of the high-K multi-quasiparticle bands in 179Re

The experimentally observed ten rotational bands in 179Re are analyzed with the particle-number conserving method for treating the cranked shell model with pairing interaction, in which the blocking effects are taken into account exactly. The experimental moments of inertia of these bands are reproduced quite well by our calculations with no free parameter and the deformation driving effects are discussed. The bandhead energies and the variation in the occupation probability of each cranked orbital are also analyzed.