饱水石灰岩骨架和流体弹性参数的估算

本文利用Niu等提出的基于临界孔隙度模型的组分弹性参数数值计算方法,把测试岩石样品的孔隙度、整体密度、纵波速度和横波速度作为数值计算的输入数据,运用双线性数值计算方法反演求出临界点、流体和骨架的12个弹性参数。具体做法是:基于临界孔隙度模型,给出三组线性关系,即密度—孔隙度,整体剪切模量—孔隙度,整体纵波模量—孔隙度,上述每组线性关系分别以孔隙度作为自变量和因变量得到两个线性方程,再把两个方程计算的结果进行加权平均得到相关的弹性参数估算值,并结合饱水石灰岩样品数据实现了弹性参数估算。数值计算结果表明,由数值计算得到的弹性参数与测试弹性参数的均值和方差相差甚微,特别是密度数据的偏差均值更小,说明文中的数值计算结果是可靠的。     

Progress in Thermal Contact Resistance

The developments of aeronautics and astronautics require engines of higher quality. The temperature distribution in combustion engine is highly influenced by the thermal conduct resistance. To predict the temperature field of the hot-end assemblies of combustion engine, the thermal contact resistance must be considered. The object of the study is to propose a model of high application including in conditions of high temperature and high pressure. Up to date, many models and empirical or semi-empirical corre...     

Research on forecasting model of sandstone deformation rate during sine wave loading segment under the lag effect

To reduce data variance caused by individual differences of different samples,a new experimental method is proposed by loading and unloading the axial forces with different frequencies and different waves of a certain load amplitude to the same rock sample without damaging it.Lag time segments are defined and fractionized into segments I and Ⅱ.Criterions for seg-mentation,definitions of relevant parameters and empirical analysis are also offered afterwards.In the course of sinusoidal loading,the serious pea...     

Modeling of multi-inclusion composites with interfacial imperfections:Micromechanical and numerical simulations

A micromechanical approach based on a two-layer built-in model and a numerical simulation based on boundary element method are proposed to predict the effective properties of the multi-inclusion composite with imperfect interfaces.The spring model is introduced to simulate the interface imperfection.These two methods are compared with each other,and good agreement is achieved.The effects of interface spring stiffness,volume ratio and stiffness of inclusions on the micro-and macro-mechanical behaviors of fib...     

桩土界面接触单元的研究与应用

为解决桥梁群桩基础在上部荷载作用下桩土界面的接触问题,根据接触非线性理论和桩土不同物理力学特性的特点,首先推导反映桩土界面滑移的刚度矩阵,然后提出处理滑移变形的均匀化方法。采用ABAQUS软件的用户子程序接口,编制桩土界面接触单元,可以描述接触在循环荷载作用下的塑性应变增长和残余相对位移,在荷载水平分量作用下的界面脱开现象,以及接触刚度的非线性增长与衰减特性。这样,桩土界面的一些重要特性可以通过有限元的方法得以体现。     

Fully Stressed Piles and Beams in a Winkler’s Medium,End-loaded by an Orthogonal Force,and with Optimum Length

A simplified method of designing fully stressed piles and beams with optimum length in a Winkler’s medium,end-loaded by an orthogonal force and without any point constraint,is proposed. A numerical algorithm distributing the mass by means of the Fully Stressed Design ( FSD) method and updating the moment by finite elements has been first implemented. The use of the FSD method is in general quite simple,and allows to obtain optimum,or close to the optimum,solutions. After having distributed the mass through ...     

啁啾对双曲正割脉冲光束空间强度分布的影响

从傍轴波动方程出发,给出了啁啾双曲正割脉冲光束在自由空间中的传输方程,研究了啁啾对双曲正割脉冲光束空间强度分布的影响。结果表明,在初始位置初始时刻啁啾对双曲正割脉冲光束空间强度的分布没有任何影响,但会影响脉冲前后沿的空间强度分布。当双曲正割脉冲光束传输以后,啁啾对双曲正割脉冲光束空间强度的分布影响很大,只要啁啾系数足够大,对于脉冲宽度大于一个甚至是几十个光波振荡周期的双曲正割脉冲光束同样存在空间奇异性。啁啾系数的大小和符号对双曲正割脉冲光束空间强度的分布有不同的影响。     

小波变换在光谱特征提取方面的应用

人们在处理高光谱图像时一般要对一些典型地物进行光谱分析、特征波段的提取,以便提取出最大量的有效信息,剔除无用或冗余的信息,然后再进行分类识别.采用小波变换的分析方法,选用合适的小波进行分解,根据分解后的高频分量中包含的重要信息,利用局部相邻的正负极值点找出对应于原始光谱曲线上每个吸收带的左右边界;利用局部过零点,即可比较精确的提取出各个吸收带的中心波长.该方法比传统的光谱特征提取方法更简洁、有效,实验证明为一种比较理想的光谱特征提取方法.     

基于高阶循环累积量的OFDM-弹性光网络信号调制格式识别

将高阶循环累积量引入基于正交频分复用(OFDM)的弹性光网络(EON)的调制格式识别中。通 过计算OFDM信号不同调制格式(BPSK、QPSK、16QAM和64QAM)的高阶循环累积量,给 出了OFDM-EON信号不同调制格式的识别阈值区间,并采用仿真方法验证了该区间的 识别准确率。结果表明,利用所提出的识别阈值区间,对波特率为28G的OFDM-EON信号(各 子载波随机设置调制格式)进行调制格式识别,在光信噪比(OSNR)为34dB时,子载波调制格式的识别准确率可达到100%。     

激光淬火+冲击复合强化处理QT800-2的实验研究

对经激光淬火强化处理后的球墨铸铁QT800-2的强化区域再进行激光冲击强化处理进行了研究。结果表明,复合强化处理后的球墨铸铁QT800-2与经激光淬火强化处理区域相比,各项机械性能都得到了较大提高,其中硬度提高了18％,耐磨性提高了100％,尤其是材料内部残余应力全部变成了残余压应力。