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.     

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。     

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。     

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。     

基于SVM的EMD端点效应抑制方法研究

针对经验模态分解在对脑电数据进行处理时存在的端点效应问题,提出了一种新的端点效应抑制方法。该方法将支持向量机和数据加窗进行结合对原始信号进行处理。该方法包括三个步骤：采用支持向量机对原始信号两端分别延拓有限个极大值和极小值;用窗函数对延拓后的数据进行加窗处理;分别对原始信号以及支持向量机延拓和加窗处理后的信号进行经验模态分解,并舍弃各阶固有模态函数中延拓的数据点。为了分析所提方法的性能,以正交性作为量化评价指标对比不同方法的性能。以人工信号和实际脑电信号为实验对象进行的模拟实验表明,相比于其他几种方法,提出的方法可有效抑制经验模态分解处理过程中端点效应问题。     

Improved Solution of the Neutron Diffusion Equation Using Wavelet Theory

The development of the fast reactor (FR) cycle is being advanced to utilize plutonium and transuranium (TRU) in Japan. In the fabrication process, it is considered that a fuel pin spirally wrapped with a thin wire is laid horizontally. Then, cooling air flows vertically from the bottom side into the gap of the pin bundle so as to suppress the temperature increase due to decay heat. From the viewpoint of safety assessment during the fabrication, a thermal hydraulic analysis method plays an important role in investigating the maximum temperature and the temperature distribution of the fuel pins. In the present paper, a subchannel analysis tool has been developed. Using the developed tool, the benchmark analysis of the mocked up experiment has been carried out, as well as the numerical investigation of a multidimensional effect of fuel cladding thermal conductivity on the maximum temperature. It is demonstrated that the multidimensional effect of the cladding thermal conductivity is not negligible in the analysis. A good agreement is achieved in the case of a comparatively large clearance size between the side wall and the pin bundle when one considers a natural convection heat transfer at the outermost boundary with a comparatively low computational cost.     

模糊正交法用于羊绒还原漂白工艺参数优化

应用模糊数学的理论和方法,以模糊综合评价值作为目标函数,得出羊绒还原漂白工艺评价指标白度及强力的隶属度和模糊综合评价值.通过模糊数学主效应分析,得到羊绒还原漂白工艺的优化条件是温度55℃,时间20 min,还原粉用量20%(owf).     

CDMA2000反向链路正交系统性能研究

基于现有CDMA2000信道结构,研究了反向链路正交方案,并利用rise-over-thermal(ROT)准则对该系统容量进行了分析。数值计算结果和动态系统级仿真表明,与非正交反向链路对比,采用反向链路正交降低了来自本小区的干扰,使系统容量有显著提高,但可用正交码资源限制了这种增益。     

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.     

低复杂度的满速率和部分分集多天线空时块码及性能

在现有几种满分集空时码的基础上,提出两种满速率和复正交的多天线空时块码方案。一种是基于时分双工(TDD)模式下最大信道增益而设计的;另一种则不再限于TDD方式,具有普遍适用性。同时利用Turbo码良好的抗衰落信道的突发错误能力,来进一步提高所提方案性能。与满分集多天线空时块码相比,该方案可实现满速率、低复杂度和部分分集,具有相对多的空间冗余信息,从而级联Turbo码后可有效弥补部分分集所带来的性能损失。仿真结果也表明在相同系统容量和级联码的情况下,所提方案比其它相应的满分集空时码有着更低的误比特率。