A MICROMECHANICAL FRAMEWORK WITH AGGREGATE-MASTIC INTERFACE EFFECT FOR PREDICTING UNIAXIAL COMPRESSION CREEP OF ASPHALT MIXTURE

According to the elastic-viscoelastic correspondence principle, an elastic microme- chanical framework taking the inclusion-matrix interface effect into account is extended for predicting viscoelastic properties of asphalt mixture, which is simply treated as elastic coarse aggregate inclusions periodically and isotropically embedded in a viscoelastic asphalt mastic matrix. The Burgers model is adopted for characterizing the matrix mechanical behavior, so that the homogenized relaxation modulus of asphalt mixture in compression creep is derived. After a series of uniaxial compression creep tests are performed on asphalt mastic in different temperature and stress conditions in order to determine the matrix constitutive parameters, the framework presented is validated by comparison with the experiment, and then some predictions of uniaxial compression creep behavior of asphalt mixture in different temperature and stress conditions are given.     

具有弹性夹层的文克勒地基上双层叠合梁的解

将双层叠合梁之间的接触状况拟合为一符合 Goodman假设的弹性夹层 ,导出了Winkler弹性地基上双层叠合梁的微分方程组及其解析解。通过引入“广义夹层反应模量”计入了夹层水平和竖向反力引起的梁截面的剪切和拉压形变效应 ,它有效地提高了计算精度 ,尤其是在双层梁结构有间断的场合。     

基于压缩感知理论的大规模MIMO系统下行信道估计中的导频优化理论分析与算法设计

针对大规模多输入多输出(multiple input multiple output, MIMO)系统信道估计中的导频设计问题,在压缩感知理论框架下,提出了一种基于信道重构错误率最小化的自适应自相关矩阵缩减参数导频优化算法.首先以信道重构错误率最小化为目标,推导了正交匹配追踪(orthogonal matching pursuit, OMP)算法下信道重构错误率与导频矩阵列相关性之间的关系,并得出优化导频矩阵的两点准则,即导频矩阵列相关性期望和方差最小化;然后研究了优化导频矩阵的方法,并提出相应的自适应自相关矩阵缩减参数导频矩阵优化算法,即在每次迭代过程中,以待优化矩阵平均列相关程度是否减小作为判断条件,调整自相关矩阵缩减参数值,使参数不断趋近于理论最优.仿真结果表明,与采用Gaussian矩阵、Elad方法、低幂平均列相关方法得到的导频矩阵相比,本文所提方法具有更好的列相关性,且具有更低的信道重构错误率.     

改进型FCC晶格材料设计与吸能特性

基于金属微观晶体结构,设计了一种改进型面心立方(FCC)晶格材料。利用ABAQUS有限元软件,对体心立方(BCC)及FCC晶格材料进行了准静态与速度为10~100 m/s的动态加载数值模拟,定量分析了两种晶格材料的能量吸收性能,给出了动态加载下晶格材料压缩平台应力及塑性能量耗散的半经验公式。结果表明:在准静态压缩载荷下,相同相对密度的FCC晶格比BCC晶格具有更优异的能量吸收性能,当相对密度为10.5%~10.6%时,FCC晶格材料的归一化比吸能是BCC晶格材料的2.6倍。此外,与常见负泊松比材料及大部分桁架晶格材料相比,相同相对密度的FCC晶格材料具有更高的比刚度、能量吸收效率及压缩力效率。     

Nanobubbles produced by hydraulic air compression technique

The anoxia of coastal water has already been a serious problem all over the word. Nanobubbles are proved to have great applications in water remediation because they could effectively increase the oxygen content and degrade organic matters in water. But the existing methods to produce nanobubbles are complicated and high cost to operate, especially in deep sea. In this paper, we presented a low-cost method, hydraulic air compression (HAC), to produce a large number of nanobubbles and proved that nanoscale gas bubbles could be produced by HAC for the first time. Nanoparticle tracking analysis was used to measure the size and concentration of produced nanobubbles. It indicated that the concentration of nanobubbles would increase as the downpipe height increases. Degassed measurements proved that produced “nanoparticles” are gas nanobubbles indeed. More dissolved oxygen in water would provide the source for larger number of nanobubble formation. Those results are expected to be very helpful for water remediation in ocean in the future.     

一类非线性微分方程的存在唯一性

在有界区域上研究了一类非线性微分方程解的存在唯一性。     

Enhanced Compression of Fundamental Solitons in Dispersion Decreasing Fibers with Negative Third-order Dispersion Ⅱ. Effects of Fiber Characteristics and Initial Soliton Width

Previous work have shown that the combined effects of negative third-order dispersion (TOD) and Raman self-scattering (RSS) can significantly enhance soliton compression in dispersion decreasing fibers (DDFs). In this paper, the effects of the negative TOD coefficient and the effective amplification of DDF′s on the performance of soliton compression are investigated. It is shown that for a given initial soliton width and a given effective amplification, there exists an optimum value of the negative TOD coefficient of the DDF at which the enhancement in soliton compression is maximum. It is also shown that the compression enhancement saturates when the effective amplification exceeds a certain value, which has been explained as a compromise between the higher-order effects induced increase of the ratio of input to output group-velocity dispersion coefficients of the DDF and the TOD induced non-adiabatic compression characteristics. The dependence of the compression enhancement on the initial soliton width have also be studied and the scheme is found works well for solitons with initial widths less than 3 ps.     

Nonlinear compression of optical solitons

In this paper, we consider nonlinear Schrödinger (NLS) equations, both in the anomalous and normal dispersive regimes, which govern the propagation of a single field in a fiber medium with phase modulation and fibre gain (or loss). The integrability conditions are arrived from linear eigen value problem. The variable transformations which connect the integrable form of modified NLS equations are presented. We succeed in Hirota bilinearzing the equations and on solving, exact bright and dark soliton solutions are obtained. From the results, we show that the soliton is alive, i.e. pulse area can be conserved by the inclusion of gain (or loss) and phase modulation effects.     

爆磁压缩装置经组合功率调节系统产生高电压的实验研究

 介绍了以爆磁压缩装置为脉冲功率能源,经变压器和爆炸金属丝断路开关组合功率调节系统,在电阻负载上产生高电压的实验研究。实验结果为：在100W 水电阻负载两端得到了约800kV的高电压脉冲,脉宽约100ns。此项工作拓宽了爆磁压缩装置的应用范围。     

傅立叶变换-主成份分析方法用于二维色谱数据的压缩和重构

结合傅立叶变换（ＦＴ）和主成份分析（ＰＣＡ）技术,实现了二维高效液相色谱数据的压缩和重构,并对不同信噪比的二维色谱测量数据进行了处理,即使对原始数据的压缩比高达２００倍,仍能很好地重构原始数据,当原始数据的信噪比较低时,阈值的选择受大振幅噪音的影响,使压缩比略有下降,但仍然能够保持信号基本不失真。