石油醚提取褐煤蜡的条件选择及优化

以石油醚为萃取剂,对云南曲靖褐煤进行了褐煤蜡提取实验研究,采用单因素试验对褐煤蜡提取率影响因素进行选择,并用正交试验设计方法对提取条件进行了优化,对优化产物进行了酸值、皂化值测定。结果表明:对褐煤蜡提取率影响最大的因素是提取温度,其次是水分,提取时间影响最小。优化工艺为:含水量为6.32%,温度为45℃,时间为150min,料液比为1∶4。在此条件下提取率达到4.97%,产物酸值、皂化值分别为:46.95 mg KOH/g、62.03 mg KOH/g。     

水泥土电阻率特性及其在粉喷桩工程中的应用研究

通过水泥土电阻率正交试验研究分析，得出影响水泥土电阻率的主要因素依次为含盐量、水泥掺入比、天然含水量、粉煤灰含量、石灰含量；同时进行了水泥土电阻率和喷粉搅拌桩身抗压强度、芯样力学性状和喷粉搅拌桩标贯击数的对比研究，探索了电阻率法在喷粉搅拌桩工程质量检测中的应用。     

Research on orbital angular momentum communication technology

As the good orthogonality between the different modes of orbital angular momentum (OAM),the application of OAM technology in wireless communication has gained increasing popularity in recent years with great potential for capacity improvement.OAM-based wireless communication technology can effectively improve spectrum utilization,but also brings some challenges.Firstly,the research status and progress of OAM technology in the field of wireless communication were introduced and the relationship between OAM and MIMO technology was compared and analyzed combined with the basic principle of OAM.Moreover,the dispute “Does OAM provides a new dimension?” was concluded.Then,the generation and reception methods of OAM were summarized.The key techniques and application fields were overviewed.Finally,the challenges of the technology in practical application were analyzed and the future development trends and follow-up research directions were point out,which would provide a reference and help for the research in this field.     

弱稀疏语音信号的欠定盲分离

为解决弱稀疏语音信号的欠定盲分离问题,根据语音信号的部分W-分离正交性,提出一种基于单源主导区间的混合矩阵盲估计方法。该方法根据单源主导区间的性质,通过二元行矢量提取单源观测样本,对单源观测样本进行K均值聚类和主成分分析来估计混合矩阵。仿真结果表明,提出的方法可有效提高分离语音的性能,与直接利用K-PCA方法相比,分离语音的平均信噪比提高了10 dB左右。     

刚弹耦合多体系统增广特征矢量及其正交性

特征矢量的正交性是用模态方法求解多体系统动力响应的前提条件。对于刚弹耦合多体系统,振型函数不具有通常意义下的正交性。本文引入了多体系统增广特征矢量的概念,解决了多体系统特征矢量的正交性问题。系统地阐述了多体系统增广特征矢量的构造方法、正交性条件、正交性证明以及增广特征矢量的重要作用。利用增广特征矢量的正交性,可实现对多体系统动力学方程的坐标解耦,使得用模态方法精确分析动力响应成为可能。     

基于椭圆光顺的推进格式结构化网格生成技术

提出了一种从结构化初始物面网格出发,结合泊松方程的离散求解、逐层推进的结构化网格的生成技术,并针对不同外形生成了贴体、光滑、正交的流场计算网格;针对具有尖锐凸角/凹角的物面,分别采用不同的网格光顺技术以改善物面拐角处的网格质量;讨论了针对不同拓扑结构网格选择源项的策略,以通过求解泊松方程进行网格光顺,改善网格生成质量。最后,采用几个不同的外形算例来验证该网格生成技术的鲁棒性及有效性,表明该网格生成技术能够针对不同的简单或复杂外形,生成较高质量的流场计算网格。     

多项式的正交性与其零点有界性的一个注记

设{φn（z））∞n0是首一复正交多项式序列,其中中。的次数为n,n≥1,且中。的零点φn的零点znj,j=1,2,…,n,满足｜=znj｜〈1．本文讨论{φn（z））n∞nm0的正交性,某个比值的有界性和条件｜znj｜〈1,J=1,2,…,几之间的联系．     

酸性KMnO_4条件下芳纶纤维的表面改性研究

利用KMnO4在酸性的环境中具有氧化性的特性对芳纶纤维进行表面改性研究,分析其表面形貌、强力以及拉伸性能的变化;采用扫描电子显微镜观察处理前后芳纶纤维的表面形态特征;以夹角余弦幅度法确定权重;利用模糊正交法的理论与方法处理试验数据,得出模糊综合评价值.从而得出最佳实验指标为:硫酸质量分数10%,KMnO4质量浓度5 g/L,处理温度为30℃,处理时间35 min.     

正则的符号蕴含正交模式

一对符号模式行(或列)向量是蕴含正交的,若存在一对与它们有相同符号模式的正交实行(或列)向量.一个没有零行或零列的n阶符号模式矩阵是符号蕴含正交的,若每一对行和列向量都是蕴含正交的.本文证明了当n为偶数时,存在k正则n阶符号蕴含正交模式的充分必要条件是1≤k≤n;当n≠5为奇数时,存在k正则n阶符号蕴含正交模式的充分必要条件是1≤k≤n且k≠2;当n=5时,存在k正则n阶符号蕴含正交模式的充分必要条件是k≠2且k≠3.     

Augmented Eigenvector and Its Orthogonality of Linear Multi-rigid-flexibel-body System

The orthogonality of eigenvector is a precondition to compute the dynamic responses of linear multi-rigid-flexi- ble-body system using the classical modal analysis method. For a linear multi-rigid-flexible-body system, the eigenfunction does not satisfy the orthogonality under ordinary meaning. A new concept augmented eigenvector is introduced, which is used to overcome the orthogonality problem of eigenvectors of linear multi-rigid-flexible-body system. The constitution method and the orthogonality of augmented eigenvector are expatiated. After the orthogonality of augmented eigenvector is acquired, the coupling of coordinates in dynamics equations can be released, which makes it possible to analyze exactly the dynamic responses of linear multi-rigid-flexible-body system using the classical modal analysis method.