基于波前倾斜的太赫兹单次测量研究

太赫兹单次测量技术可以对一些超快不可逆过程进行快速测量,在蛋白质变性、核爆模拟分析等领域具有广阔的应用前景。从飞秒激光放大器发出的光脉冲分成两束并分别经过两块光栅产生波前倾斜,一束作为抽运光激发铌酸锂晶体,基于光整流效应产生高功率太赫兹波;另一束作为探测光,采用正交平衡探测法探测。利用该光路产生太赫兹脉冲并对其进行单次测量,系统的时间窗口为16.8 ps,频谱范围覆盖0.1～1.6 THz。     

基于两层分解算法和改进SVM的油田采出水处理效果预测研究

准确的水质预测是评估油田联合站采出水处理效果的重要依据,为水质预警提供科学依据.传统方法存在主观性强和耗时性长等缺点,现有部分研究借助于机器学习方法,但对数据噪声和数据非线性考虑不足.本研究提出一种基于两层分解算法与改进支持向量机相结合的预测方法.通过两层分解算法消除冗余噪声,提取初始数据主要特征.利用分层抽样对原始数...     

基于小波包变换与近似熵的储集层识别

通常不同地层特征对应的地震波复杂程度均有差异.近似熵是一种反映信号复杂程度的特征量,对储层特征有一定反映.但是,地震波是有一定带宽的信号,在此带宽内,可能某一部分频段对油气层较为敏感,而其他频段的信号则对油气层的反应不够敏感,如果直接进行近似熵的计算,其结果往往不能很好地反映储层特征.鉴于这种情况,对小波包变换和近似熵结合进行储集层预测的方法进行研究,即对小波包分解的结果进行近似熵计算.实际资料计算结果表明,结合小波包分解和近似熵的储层识别方法,能够精确刻画储层形态.     

高压断路器梅花触头的温度检测

随着电力系统的发展,高压电气设备的安全性、可靠性凸显重要。而高压断路器工作于最佳状态又是设备安全可靠的重要保证。为了实现高压断路器中设备的接触点和开断点一一梅花触头处的温升的实时检测,本文介绍了基于蓝牙传输的无线测温系统,克服了高压电力系统中检测困难,测量精度差等难题,为设备的故障发现、维修提供了可靠的依据。     

Oldroyd-B流体的解耦有限元算法

建立了求解稳态Oldroyd-B流体模型的有限元算法.为了降低该流体模型的耦合性和有限元方程的求解规模,考虑将Oldroyd-B流体模型解耦为Stokes方程和本构方程.对于Stokes问题,使用加权最小二乘有限元方法求解;而对于含有对流项的本构方程,则采用具有较好数值稳定性的流线迎风Petrov-Galerkin(SUPG)方法求解.针对本构方程的非线性特点,利用迭代算法将其进行线性化处理.分析了解耦有限元解的先验误差估计.通过粘弹性Oldroyd-B流体在管道内的流动问题,验证了算法的有效性和收敛性.     

Variation of yield stress of Daqing crude oil with pipelining history

The yield stress of waxy crude oil is a fundamental parameter in the calculation of pipelining technique and analysis of flow safety for the heated oil transported through pipeline.Daqing crude oil was studied and the variation of yield stress with shear history was explored through simulation experiment of pipelining.It is found that the effect of throughput variation or shear rate on yield stress is not obvious.With the decrease of final dynamic cooling temperature,the yield stress of waxy crude oil decreases,but there exists a little increase at the beginning.The prediction model of yield stress for waxy crude oil under the condition of shutdown is developed and it can be used to predict the yield stress of Daqing crude oil at certain heating temperature,final dynamic cooling temperature and measurement temperature.For the 139 groups of yield stress data of Daqing crude oil from the simulation experiment of pipelining,the result of prediction with this model shows that the average relative deviation between the yield stress measured and predicted is 30.27%,and the coefficient of correlation is 0.962 3.     

Relationship between waxy crude viscosities and wax crystal microstructure

It is important and profound to quantitatively study the relation between rheology and microstructure for development of the microstructural mechanism of crude oil rheology and even for the waxy crude oil pipelining.However,due to the high complexity and irregularity of wax crystal morphology,quantitative characterization is hard to achieve.This has hampered further study on the rheology-microstructure relationship.A new approach combined the fractal geometry and the stereology theory is presented for quantifying the intricate wax crystal morphology and structure.Based on the characterization,the effects of microstructures and oil composition on the waxy crude viscosities are analyzed quantitatively.It further validates the previous qualitative research and enriches understanding into the microstructural mechanism of waxy crude oil rheology.     

基于奇异值分解法的二元矩阵聚类算法研究

文献检索时通常会用到LSI(Latent Semantic Indexing)算法.针对算法中返回值受阈值大小影响的问题,对算法中由奇异值分解SVD(Singular Value Decomposition)得到的左、右奇异值矩阵,用k-means算法对其进行聚类,提出了LSI改进算法.实验结果表明,与传统的LSI方法相比,改进算法在提供k-means算法分类的维度时获得了更好的性能,证明了算法的有效性.     

基于色噪声背景下线性滤波器组检测性能的研究

随着5G新空口信号处理技术的广泛应用,为了提高大规模组网中基站(天线)滤波器检测系统的检测性能,本文提出了一种基于色噪声背景下对信号进行检测判决的线性滤波器组(LFB)检测系统,即在传统匹配滤波器检测系统中加入白化滤波器级联组构成线性滤波器组检测系统,首先对二元确知信号检测判决系统中相干相移键控系统(CPSK),相干频移键控系统(CFSK),和相干启闭键控系统(COOK)的检测性能进行分析。其次,在此基础上推广到对多元(M元信号检测)确知信号检测性能进行分析。最后,经过仿真,根据最大输出信噪比准则,采用白化滤波器组将色噪声滤除有色部分后通过检测判决系统,获取在色噪声背景下最佳的线性滤波器组(Linear Filter Bank,LFB)(相关接收机)的检测性能。