Space–Time Power Schedule for Distributed MIMO Links Without Instantaneous Channel State Information at the Transmitting Nodes

A space-time optimal power schedule for multiple distributed multiple-input multiple-output (MIMO) links without the knowledge of the instantaneous channel state information (CSI) at the transmitting nodes is proposed. A readily computable expression for the ergodic sum capacity of the MIMO links is derived. Based on this expression, which is a non-convex function of power allocation vectors, a projected gradient algorithm is developed to optimize the power allocation. For a symmetric set of MIMO links with independent identically distributed channels, it is observed that the space-time optimal power schedule reduces to a uniform isotropic power schedule when nominal interference is low, or to an orthogonal isotropic power schedule when nominal interference is high. Furthermore, the transition region between the latter two schedules is seen to be very sharp in terms of nominal interference-to-noise ratio (INR). For MIMO links with correlated channels, the corresponding space-time optimal power schedule is developed based on the knowledge of the channel correlation matrices. It is shown that the channel correlation has a great impact on the ergodic capacity and the optimality of different power scheduling approaches.     

Two-channel constrained least squares problems: solutions using power methods and connections with canonical coordinates

The problem of two-channel constrained least squares (CLS) filtering under various sets of constraints is considered, and a general set of solutions is derived. For each set of constraints, the solution is determined by a coupled (asymmetric) generalized eigenvalue problem. This eigenvalue problem establishes a connection between two-channel CLS filtering and transform methods for resolving channel measurements into canonical or half-canonical coordinates. Based on this connection, a unified framework for reduced-rank Wiener filtering is presented. Then, various representations of reduced-rank Wiener filters in canonical and half-canonical coordinates are introduced. An alternating power method is proposed to recursively compute the canonical coordinate and half-canonical coordinate mappings. A deflation process is introduced to extract the mappings associated with the dominant coordinates. The correctness of the alternating power method is demonstrated on a synthesized data set, and conclusions are drawn.     

木犀科植物花粉的扫描电镜研究

植物花粉的形态特征具有种属特异性。本文用扫描电子显微镜观察了木犀科(Oleaceae)的六属八种植物花粉的形态特征。结果表明,除迎春有个别四萌发沟外,其它花粉都是三沟型,外壁纹饰均为网状。但各种植物花粉的细微形态仍有明显差异。因此,用扫描电镜观察研究植物花粉的亚微形态特征,可为植物分类提供一些必要的形态依据。     

基于GNN的矩阵分解推荐算法

相较于协同过滤,矩阵分解有着更好的拓展性和灵活性,但同样受到数据稀疏和冷启动的困扰。针对上述问题,提出一种融合GNN和PMF的推荐算法GNN_MF。该算法通过神经网络对社交网络图以及用户项目图进行建模,将两个图内在的联系起来,学习目标用户在社会空间以及项目空间上的特征向量。通过MLP将两个特征向量串联提取用户的潜在特征向量,集成在概率矩阵分解模型上,产生预测评分。在真实数据集Epinions、Ciao上的大量实验表明,GNN_MF算法的均方根误差和平均绝对误差较传统PMF分别降低了2.91%、3.10%和4.83%、3.84%。验证了GNN_MF算法在推荐系统中的有效性以及可行性。     

基于GMD-DPC/THP的两组Alamouti非线性预编码系统

针对Alamouti空时块编码复用增益损失的问题,提出了两组Alamouti编码方案;在此基础上,为了改善系统的误码率（Bit Error Rate,BER）性能和简化接收端复杂度,提出将几何均值分解（Geometric Mean Decomposition,GMD）算法和非线性预编码技术相结合的两组Alamouti传输方案。本方案的设计方法为：首先等效出两组Alamouti空时块编码系统的信道矩阵;进而,通过GMD算法对等效信道矩阵进行收发端联合设计;最后,在发射端应用脏纸（Dirty Paper Coding,DPC）和Tomlinson-Harashima Precoding（THP）非线性预编码技术,消除发送信号间的干扰,从而使系统获得更好的误码率性能。通过仿真结果对比发现,提出的系统可以显著地改善误码率性能。     

面向对象有限元并行计算框架PANDA的多物理场耦合服务

针对结构分析软件面向多物理场的应用,分析讨论面向对象有限元并行计算框架PANDA的多物理场耦合服务设计,即多物理场分析类型的扩充能力、不同物理场间的数据传递和多物理场耦合分析的求解策略.在PANDA提供的多物理场耦合服务的基础上,开展热-力耦合分析功能的程序开发,实现热弹性分析功能.热弹性分析算例计算结果与ANSYS的...     

“先锋”是一种立场

如今学术界对"先锋艺术"①的定义普遍采用了德国学者比格尔(Burger,P)的论断,即先锋艺术是对"自律艺术"进行颠覆的艺术形态。通过这种定义来将其与浪漫主义、象征主义、唯美主义、后现代主义进行区分。但笔者认为这种区分实际上正是一种现代性观念的体现,强调对各个事物进行严格的区分与划界。事实上,先锋艺术首先表现为一种强烈的精神立场甚至是意识形态,因此比格尔的定义实际上忽视了先锋艺术中最为核心的因素。     

单层球面网壳结构的力学性能研究

基于非线性有限元方法，研究了单层球面网壳结构的内力分布规律及结构变形特点，并针对力学计算模型、结构失跨比、外荷载分布等主要因素，研究其对单层网壳结构力学性状的影响情况。得出了工程中常用的单层球面网壳的荷载传递方式以及存在于结构内的力流方向，为在工程设计中控制力流，并设计力流的导向提供理论指导。     

结构工程设计自动参数化图形系统的开发研究

以钢结构设计专家系统（ＥＳＯＳＳＤ）图形系统为例，介绍了其设计原理及主要思想，提供了建造ＡＣＡＤ图形函数库，利用ＭＳ－ＦＯＲＴＲＡＮ实现模型代真等方法，并对系统参数化建模及施工图绘制进行了探讨和研究。     

广西大新难处理低品位碳酸锰矿加工工艺研究

针对广西大新县难处理低品位碳酸锰矿,分别采用重选、磁选、以及浮选工艺进行探索性试验研究。试验结果表明强磁选是该矿石的最佳工艺方案,经过选别,最终得到品位19.06%,回收率为82.00%的锰精矿。