内波、潮导致的声简正波幅度起伏及其深度分布

分析2005黄海声传播—内波实验传播起伏数据,观察（1）号声简正波幅度起伏及其深度分布特征。非线性内波（IW）通过接收阵可以导致脉冲峰值约5 dB起伏,幅度起伏垂向分布与简正波本征函数的微分分布吻合良好,（M2）潮致信号幅度起伏也满足相同深度分布特性。然而内波和潮致起伏的垂向相位变化明显不同:前者本征函数峰值两侧起伏信号反相,而后者近乎同相。前者由接收器与简正波分布的相对移动决定,而后者取决于简正波和水听器位置变化的复合效应。      

镜面起伏对1.55μm Si基MEMS光滤波器的影响

用传输矩阵方法,在简化的光学模型基础上,分别讨论了分布式Bragg反射镜DBR(Distributed Bragg Reflector)的生长精度及镜面起伏对1.55 μm Si基MEMS(Micro-Electro-Mechanical-System)可调谐光滤波器透射谱的影响.计算表明:DBR生长误差仅使主透射峰位置发生变化,而镜面起伏是导致主透射峰性能劣化的主要原因,它使得FWHM增大,透射峰强度下降.理论计算结果能较好地解释实验现像.在此基础上,进一步讨论了引起镜面起伏的多种原因,并提出了可能的解决方法.     

基于数字高程模型的起伏地形对紫外光非直视通信的路径损耗

针对起伏地形环境下紫外光非直视通信路径损耗大、站点选址难的问题,提出了基于数字高程模型(DEM)的紫外光非直视传输的最佳收、发仰角求解方法。依托紫外光非直视单次散射模型,研究了路径损耗与收、发仰角之间的关系。针对不同地形原始DEM数据,通过插值提高分辨率,并提出了切线传输方案。采用顺序遍历法对收、发端位置及仰角变化对通信系统路径损耗的影响进行了研究。仿真结果表明,路径损耗在[10°,80°]收、发仰角区间内为增函数。在使用反距离加权插值法提高数据分辨率后,路径损耗值相较原始数据分别降低了0.014 dB、0.043 dB和0.385 dB。当按切线传输方案布设时,通信系统路径损耗值最小,设计的仿真程序可为收、发端站点科学布设提供支持。     

南海夏季沿岸内波与定点声起伏特征分析

利用2020年6月海南岛沿岸试验数据,分析内波及声能量起伏特征。试验海域以全日潮内波为主,并伴随有高频内波活动。内波活动引起360 Hz单频信号20 km定点声起伏峰峰值超过30 dB, 320～400 Hz线性调频信号起伏峰峰值超过15 dB。利用测量数据结合数值仿真,讨论了内波引起单频信号和线性调频信号呈现不同起伏特征的原因。结果表明:试验海域内波活动导致单频声场模态间干涉条纹出现移动,进而导致接收位置处特定频率的声能量出现大幅度的快速起伏;由于带宽内的平均作用,宽带信号的能量起伏远小于单频信号的能量起伏。当内波传播速度变化时,各内波成分在声传播路径上出现的时间和位置发生了变化,使得声场出现剧烈起伏的时间也随之变化。     

高能多粒子末态的多重分形维数与动力学起伏强度

研究了多重分形维数与动力学起伏强度的关系,给出了一个能直接描述高能多粒子末态动力学起伏强度的特征参量,并指出了这一参量的适用范围以及在实际高能实验中的应用.     

湍流内尺度对光波起伏频谱的影响

在不同湍流内尺度情况下,对大气湍流引起的光波光强闪烁和到达角起伏的时间频谱特征进行了实验研究。由于实际大气湍流的复杂性和不可控性,利用大气湍流模拟箱来生成具有不同内尺度的大气湍流实验环境。利用位置敏感探测器对光波的光强闪烁和到达角起伏进行了同时测量,并反演得到了光传输路径上的湍流内尺度。实验结果显示:湍流内尺度为2.7~5.0 mm,对应同一湍流内尺度,闪烁频谱和到达角起伏频谱在高频段以相同的幂指数关系下降,幂指数的绝对值与湍流内尺度的大小呈线性关系,随着内尺度的增大,频谱指数变化区间逐渐向低频方向移动。     

高能重离子碰撞中正负荷电粒子比单事例起伏研究

用强子和弦级联模型,JPCIAE及相应的Monte Carlo事例产生器,研究相对论性核–核碰撞中有限快度区间内正负荷电粒子比单事例起伏与能量、中心度、共振态衰变及快度间隔的关系.JPCIAE模型能够较好地符合CERN/SPS能区Pb+Pb碰撞的实验结果.本文还用此模型预言了RHIC能区Au+Au碰撞和ALICE能区Pb+Pb碰撞中的正负荷电粒子比单事例起伏.可以看出碰撞能量、中心度、共振态衰变及快度间隔对正负荷电粒子比单事例起伏的影响都不大.     

158GeV/c的Pb–Pb碰撞中的J/ψ抑制现象研究

在Blaizot等人建立的模型基础上,我们考虑了核–核碰撞中的参与者数与核子–核子碰撞数的起伏效应对J/?ψ产生的影响,并对NA50合作组在入射动量为158GeV/c的Pb-Pb碰撞中的实验数据进行了分析,理论结果与实验数据符合的很好     

消光起伏自相关频谱法颗粒测量技术

消光起伏相关频谱法(TFCS)是一种新的颗粒测量方法。采用一束窄光束照射两相流系统,照射区中颗粒浓度的起伏所导致的透射光起伏信号中包含了颗粒的粒径和浓度信息,对光束的透过率信号作相关处理得到消光起伏相关频谱,可用来同时测量两相流中颗粒的粒径分布和体积浓度。由于在测量原理和结构上非常简单,这种方法可用来实现在线、实时测量。本文介绍消光起伏自相关频谱的测量原理,并给出部分实测结果。     

水平均匀大气中多束光在接收面上的相关性及其对光强起伏的影响

在科尔莫戈罗夫理论的基础上，推广了光束在接收面上相关函数的物理含义。分析了多光束在接收面上的相关性。并在此基础上形成多光束光强起伏方差的解析表达式。分析结果表明，随着信道间距的增加，信道相关性下降。到达接收面的光强起伏方差降低；当信道完全重合，即相关系数变为1时，叠加后的光强起伏方差没有明显降低。与单光束时没有区别；在允许范围内增加光束数目可降低光强起伏。     

快度间隔分析与逐事件快度关联

本文推导了逐事件快度间隔的起伏与逐事件快度关联的关系. 分析表明：快度间隔分析中新的和有意义的部分是推广的两粒子快度关联矩. 对于一些特殊的两粒子和矩阶数这些矩有明确的物理意义.     

高能核子-核子和核-核碰撞中电荷起伏的测量

利用强子-强子碰撞的模型PYTHIA以及核-核碰撞的模型RQMD比较了各种电荷起伏测量量的快度依赖性，结果发现，这些测量量对快度的依赖性依赖于模型. 但是，电荷关联能很好地测量整体电荷守恒以及短程快度关联性质. 因此，被认为是一个好的反应电荷起伏的测量量.     

Charged particle fluctuation in Au+Au collision

In this paper,we present the centrality,transverse momentum region and rapidity window size dependence of charged particle fluctuation from Relativistic Quantum Molecular Dynamics (RQMD) model.D Q,Γ Q and Φ Q all depend on the rapidity windows we chosen.ν +-,dyn is a promising observable in experiments,it weakly depends on the acceptance.The beam energy dependence of ν +-,dyn has been studied to present baseline prediction for net charge fluctuations in experiments.     

Strong-coupling diffusion in relativistic systems

Different from the early universe, heavy-ion collisions at very high energies do not reach statistical equilibrium, although thermal models explain many of their features. To account for nonequilibrium strong-coupling effects, a Fokker-Planck equation with time-dependent diffusion coefficient is proposed. A schematic model for rapidity distributions of participant baryons is set up and solved analytically. The evolution from SIS via AGS and SPS to RHIC energies is discussed. Strong-coupling diffusion produces double-peaked spectra in central collisions at the higher SPS momentum of 158 A.GeV/c and beyond.     

The rapidity distribution of the cascade inside deuteron in πd high energy collisions

The problem of the existence of internuclear cascade and its characteristics are analysed in the π^? d experiment at 205 GeV/c. Two versions of the additive quark model are used to obtain the mean multiplicity and the rapidity distribution of charged particles produced through cascading. It is shown that the cascading effect does exist. The particles produced through this effect have the rapidity distribution very similar as in elementary low energy hadron-nucleon interactions. Both the rapidity distribution and the mean multiplicity do not depend on the version of the additive quark model which was used to obtain them.     

Centrality and energy dependence of rapidity correlation patterns in relativistic heavy ion collisions

The centrality and energy dependence of rapidity correlation patterns are studied in Au+Au collisions by using AMPT with string melting,RQMD and UrQMD models.The behaviors of the shortrange correlation(SRC)and the long-range correlation(LRC)are presented clearly by two spatial-position dependent correlation patterns.For centrality dependence.UrQMD and RQMD give similar results as those in AMPT,i.,e., in most central collisions,the correlation structure is flatter and the correlation range is larger,which indicates a long range rapidity correlation.A long range rapidity correlation showing up in RQMD and UrQMD implies that patton interaction is not the only source of long range rapidity correlations.For energy dependence,AMPT with string melting and RQMD show quite different results.The correlation patterns in RQMD at low collision energies and those in AMPT at high collision energies have similar structures,i.e.aconvex curve.while the correlation patterns in RQMD at high collision energies and those in AMPT at low collision energies show fiat structures,having no position dependence.Long range rapidity correlation presents itself at high energy and disappears at low energy in RQMD,which also indicates that long range rapidity correlations may come from some trivial effects,rather than the parton interactions.     

高能碰撞多粒子末态间歇现象与关联积分的研究

用理论分析和Monte Carlo模拟表明:研究间歇现象时用关联积分代替阶乘矩的统计会改变快度bin减小时的反常标度行为. 指出,关联函数积分与阶乘矩可能分别反映不同的物理内容.提出了一种随机移动分bin起点的统计阶乘矩方法以消除分bin造成的人为因素.证明了,“钉子”事件对间歇指数有重要贡献.     

Two-particle correlations in 360 GeV/cp p interactions

Two particle correlations of hadrons produced in 360 GeV/cpp interactions are investigated in the transverse plane and in rapidity. The data were obtained at the European hybrid spectrometer equipped with a rapid cycling bubble chamber. The observed transverse and rapidity correlations are compared with the one string LUND-and a two string dual parton-model. These models predict in general stronger correlations in the transverse plane and much weaker correlations in rapidity than found in the data. The LUND-FRITIOF-and multichain dual parton models provide a better reproduction of the data, although the agreement is not yet satisfactory. Only the UA5 cluster model GENCL shows agreement with the data.     

Gluon saturation and baryon stopping in the SPS, RHIC, and LHC energy regions

A new geometrical scaling method with a gluon saturation rapidity limit is proposed to study the gluon saturation feature of the central rapidity region of relativistic nuclear collisions. The net-baryon number is essentially transported by valence quarks that probe the saturation regime in the target by multiple scattering. We take advantage of the gluon saturation model with geometric scaling of the rapidity limit to investigate net baryon distributions, nuclear stopping power and gluon saturation features in the SPS and RHIC energy regions. Predictions for net-baryon rapidity distributions, mean rapidity loss and gluon saturation feature in central Pb+Pb collisions at the LHC are made in this paper.     

Jet–jet and hadron–jet correlations in hadro- and electroproduction

We discuss, in the framework of perturbative QCD at next to leading order, two related observables which are usually considered to provide tests of the BFKL dynamics: jet–jet correlations at Tevatron energies and forward particle–jet correlations at HERA. In the first case we study the rapidity gap dependence of the azimuthal correlations and find slightly too strong correlations at large gap. In the second case we discuss the cross section as well as the azimuthal correlations over a rapidity gap range of 5 units. We find that the requirement of a forward particle imposes strong kinematical constraints which distort the distributions, notably at small rapidity gaps. We also show that the decorrelation is stronger in electroproduction than in hadron–hadron collisions. Unfortunately data are not yet available for comparison.