波浪作用下单桩基础周围海床液化机制研究

建立波浪作用下单桩周围三维海床动力响应模型,考虑自重影响下的海床长时间固结过程。采用已有物理模型试验数据对模型进行验证,证实其具有较好的适用性。模拟波浪作用下单桩周围三维海床液化区域,通过定量分析超孔隙水压力和土体初始有效应力的变化,讨论单桩插入深度对海床液化的影响机制。研究表明,单桩插入深度发生变化时,土体初始有效应力对海床液化的影响要大于超孔隙水压力,且影响程度随着插入深度的增加而逐渐增大。     

一种基于OpenMP的高效GPS卫星钟差实时估计方法

提出基于单观测值的Kalman滤波快速计算方法,并引入共享存储并行编程（OpenMP）技术实现协方差快速更新,从而实现非差GPS卫星钟差的快速实时计算。均匀选取55个IGS参考站,计算2017-03-20~03-30采样率为60 s的卫星钟差。与IGS事后30 s钟差相比,两者具有很好的一致性,RMS互差优于0.5 ns。选取未参与钟差解算的10个IGS参考站进行精密单点定位,结果表明,实时静态PPP水平方向精度优于2 cm,高程方向精度为2~4 cm;实时动态PPP水平方向精度为2～4 cm,高程方向精度为4～6 cm,能够满足实时PPP的精度要求。该方法在主频1.2 GHz服务器上8线程并行模式下单历元耗时4 s,相比串行模式效率提升1/3。     

原子掺杂对单元材料结晶能力的影响

2009年我们建立了一个凝结势模型用以预测材料形成单晶体的能力,表明单元体材料(Ni,Al,Cu,Ar,Mg)的结晶能力随凝结势的增大而单调增强.本文将凝结势模型应用于二元材料体系,并结合分子动力学模拟研究了6% Al原子掺杂对于Ni单晶材料结晶能力的影响.模拟结果发现,Al元素的掺杂会大大减弱Ni单晶的结晶能力,在此基础上提出了二元材料体系凝结势的定义,表明凝结势模型可广泛应用于预测二元体材料的结晶能力.     

周期脉冲撞击的两分量Bose-Einstein凝聚系统的单粒子相干和对纠缠

在周期脉冲撞击的两分量Bose-Einstein凝聚系统中,研究了量子混沌对单粒子相干和对纠缠性质的影响.研究表明,混沌促使单粒子相干发生强烈衰减并保持着较低的相干度,同时对纠缠出现最大值并在较短时间后消失.利用单粒子相干的这种性质可以直接测量量子混沌存在的相空间结构,有利于预防Bose-Einstein凝聚的瓦解和控制凝聚体的混沌行为.     

Single electron loss in the collisions of C3 + and atomic hydrogen

This paper studies the projectile electron loss cross sections of C^{3 +} colliding with atomic hydrogen in the frame work of extended over-barrier model at intermediate velocities (25 keV/u--600 keV/u). The electron loss is calculated in terms of the interaction between the screened target nucleus and the active projectile electron and of the interaction between projectile electron and target electron. Compared with the convergent close-coupling calculations, screening and anti-screening calculations, this model satisfactorily reproduces the experimentally obtained energy dependence of the electron-impact ionisation cross sections and the single electron loss cross sections over the energy range investigated here.     

Brillouin scattering study on elastic and piezoelectric properties of laser irradiated ZnO single crystals

Brillouin light scattering technique can be successfully used to determine the whole set of elastic and piezoelectric constants of a ZnO single crystal irradiated by different laser energy densities, into a micron range (radiation layer thickness). It is found that the scattering intensity, the linewidth and the Brillouin scattering shift of acoustic phonons are all strongly dependent on laser energy density. Based on the sound propagation equations and these results, the directional dependences of the compressional and shear moduli of the irradiated ZnO sample in the (001) plane are investigated. It is found that under an appropriate laser condition, 248 nm KrF excimer laser irradiation can significantly improve the surface quality and increase the elastic properties of ZnO single crystal. This procedure has potential applications in the fabrication of ZnO-based surface acoustic wave and optic-electronic devices.     

九江-瑞昌主-余震的波速比变化初探

根据流动台网对九江-瑞昌地震序列的定位结果,采用单台波速比方法,计算各流动台的波速比变化,得出以下结果:①各台波速比存在一定幅度的变化,但变化形态不一致,这可能与震源区应力调整有关:九江台和武蛟台的波速比在2006年4月下中旬至6月中旬这段时间较明显处于低值区间,相应的主余震的M-T图显示余震活动在该段时间内强度和频度有较明显的增强.②沿以武蛟和狮子洞两台连线的NW走向的波速比最小,结合主-余震北西向较优势分布和震源机制解的其中一组NW向节面,推断北西向断裂可能是九江-瑞昌5.7级主震的发震构造.     

单一地震事件与多个地震事件的定位方法及应用

主要介绍各种地震定位方法,概述各种地震定位方法的基本原理,重点介绍Geiger的经典方法以及在此基础上建立的各种线性方法:单一地震事件定位法与多个地震事件定位法以及对每一种地震定位方法的应用情况,尤其是国内的应用情况做了总结;同时指出各种方法的特点,并进行相应的比较.     

The evolution of pore pressure fields around standard and ball penetrometers: influence of penetration rate

Rate effects are examined in the steady pore pressure distribution induced as a result of penetration of standard and ball penetrometers. The incompressible flow field, which develops around the penetrometer is used to define the approximate soil velocity field local to the penetrometer tip. This prescribes the Lagrangian framework for the migration of the fluid saturated porous medium, defining the advection of induced pore pressures relative to the pressure‐monitoring locations present on the probe face. In two separate approaches, different source functions are used to define the undrained pore fluid pressures developed either (i) on the face of the penetrometer or (ii) in the material comprising the failure zone surrounding the penetrometer tip. In the first, the sources applied at the tip face balance the volume of fluid mobilized by the piston displacement of the advancing penetrometer. Alternately, a fluid source distribution is evaluated from plasticity solutions and distributed throughout the tip process zone: for a standard penetrometer, the solution is for the expansion of a spherical cavity, and for the ball penetrometer, the solution is an elastic distribution of stresses conditioned by the limit load embedded within an infinite medium. For the standard penetrometer, the transition from drained to undrained behavior occurs over about two orders of magnitude in penetration rate for pore pressures recorded at the tip (U1) and about two‐and‐a‐half orders of magnitude for the shoulder (U2). This response is strongly influenced by the rigidity of the soil and slightly influenced by the model linking induced total stresses to pore pressures. For the ball penetrometer, the transition from drained to undrained behavior also transits two‐and‐a‐half orders of magnitude in penetration rate, although it is offset to higher dimensionless penetration rates than for standard penetration. Copyright © 2012 John Wiley & Sons, Ltd.     

从花岗岩中提纯某些单矿物的流程

本文经多年的人工重砂分析,从花岗岩中分离提纯出二十多种单矿物,从而总结了一套分离提纯花岗岩单矿物的简易流程。此流程设备简单,成本低,只要与人工精淘密切配合,可获得纯度较高的单矿物。