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。     

机匣-双转子高维系统建模与实验验证

以机匣-双转子实验台为研究对象,基于ANSYS建立了可表征复杂结构的高精度实体有限元模型,应用Craig-Bampton模态综合方法实现了子模型维度缩减与整机动力学模型的组装。通过对比临界转速和振型验证了缩减模型的有效性,借助三维频谱图和轴心轨迹,分析了系统稳态响应特征,进行了实验验证。结果表明,发展的机匣-双转子系统建模及模型缩减方法精确、高效,为实际航空发动机机匣-双转子系统的动力学研究提供了参考。     

超声辅助提取小米谷糠油工艺优化

本研究探讨了小米谷糠前处理方式和新鲜程度对小米谷糠油提取率的影响，采用超声波辅助技术，选取最适提取溶剂，通过单因素实验和响应面分析优化小米谷糠油提取工艺，并分析了小米谷糠油脂主要理化性质及其脂肪酸组成。结果表明:选用新鲜小米谷糠，经过温度为121 ℃红外加热15 min处理；选择无水乙醇作为最佳提取溶剂，浸提时间为2 h、料液比为1:6.5 g/mL、浸提温度为56 ℃，在此条件下小米谷糠油提取率为78.57%；各因素对小米谷糠油提取率的影响程度的顺序依次为:料液比>浸提温度>浸提时间；该条件下提取的小米谷糠油酸值、过氧化值均符合《食品安全国家标准 植物油》（GB2716-2018）米糠油的指标；小米谷糠油的脂肪酸主要成分为棕榈酸、硬脂酸、油酸、亚油酸和亚麻酸，不饱和脂肪酸含量占总脂肪酸含量的90.58%，其中亚油酸含量高达72.31%。本研究提出的超声辅助无水乙醇提取小米谷糠油工艺路线是可行的，可为小米谷糠进一步开发利用提供重要的理论支撑。     

防止外墙抹灰开裂施工的措施

如何防止外墙开裂现象发生，减少维修成本，满足用户愿望，必须加大材料控制力度，改善施工作业条件，完善工艺控制措施，加强成品护意识。