Improved spectrum sharing algorithm based on feedback control information in cognitive radio networks

In order to avoid the system performance deterioration caused by the wireless fading channel and imperfect channel estimation in cognitive radio networks, the spectrum sharing problem with the consideration of feedback control information from the primary user is analyzed. An improved spectrum sharing algorithm based on the combination of the feedback control information and the optimization algorithm is proposed. The relaxation method is used to achieve the approximate spectrum sharing model, and the spectrum sharing strategy that satisfies the individual outage probability constraints can be obtained iteratively with the observed outage probability. Simulation results show that the proposed spectrum sharing algorithm can achieve the spectrum sharing strategy that satisfies the outage probability constraints and reduce the average outage probability without causing maximum transmission rate reduction of the secondary user.     

Consensus intuitionistic fuzzy group decision-making method for aircraft cockpit display and control system evaluation

A novel group decision-making (GDM) method based on intuitionistic fuzzy sets (IFSs) is developed to evaluate the ergonomics of aircraft cockpit display and control system (ACDCS). The GDM process with four steps is discussed. Firstly, approaches are proposed to transform four types of common judgement representations into a unified expression by the form of the IFS, and the features of unifications are analyzed. Then, the aggregation operator called the IFSs weighted averaging (IFSWA) operator is taken to synthesize decision-makers’ (DMs’) preferences by the form of the IFS. In this operator, the DM’s reliability weights factors are determined based on the distance measure between their preferences. Finally, an improved score function is used to rank alternatives and to get the best one. An illustrative example proves the proposed method is effective to valuate the ergonomics of the ACDCS.     

“竹林七贤”名号考

北宋司马光《资治通鉴》(卷七十八)的篇目《魏记》对竹林七贤的评价,是一个具有贬义的重要转折。南宋祝穆《古今事文类聚别集.礼乐部》注引的《魏记》内容,并不是马鹏翔所说的《隋书.经籍志》中的"《魏纪》十二卷,左将军阴澹撰",而应该是司马光《资治通鉴》(卷七十八)的篇目《魏记》;在祝穆《古今事文类聚别集.礼乐部》注引资料中,并非只引用书目,有时会书目、篇目兼引,有时只引用篇目,或概括引述,引用资料来源并不规范。在没有确凿证据出现之前,较早记载"竹林七贤"名号的文献,还是以东晋孙盛所著《魏氏春秋》和刘孝标注引的《晋阳秋》为好。     

Construction of a bacterial artificial chromosome library for Gossypium herbaceum var. africanum

Gossypium herbaceum var. africanum is the only wild cotton species within the cultivated diploid G. herbaceum. As the A sub-genome donor of tetraploid cotton, it is characterized by its resistance to insects, diseases, and other adversities. We have constructed the first bacterial artificial chromosome library (BAC) for G. herbaceum var. africanum. With high quality and broad coverage, this library includes 75000 clones, with an average insert size of about 115 kb and fewer than 4% empty clones. Our library is approximately five-fold the size of the A-genome (1667 Mb) and it provides 99.3% probability for isolating genes of interest or their sequences. Using nine SSR markers that are located on five different chromosomes and linked with resistance to Verticillium wilt, seven of nine could amplify the 40 superpools and got 1-14 hits. Because of its moderate wide coverage and relative large insert size, this library will be an important genomic resource for classifying and analyzing the evolution of cotton species, as well as for isolating disease-resistance genes and control elements.     

长距离掘进工作面大格局施工优化

一、概况 W3227工作面位于钱营孜煤矿西二采区南翼四阶段，为西二采区首采面。工作面机巷设计长度3172m．标高-580～-560m；风巷设计长度3095m．标高-480～-540m；两巷方位角187°：开切眼长305m。工作面内褶曲和断层构造发育，整体构造形态呈两个宽缓的向斜夹一宽缓的背斜，褶皱构造造成煤层产状变化较大，倾向在95～115°之间，倾角在5～15°。面内小构造较多，但没有落差大于lOm的断层，机巷与切眼交叉附近构造复杂。     

高速铁路富水浅埋软弱围岩综合施工技术

以南广铁路许村隧道为实例,介绍了富水浅埋软弱围岩隧道的地质预报、地表加固、变形观测、开挖支护、衬砌等综合施工技术,施工中容易出现的问题以及采取的对策和取得的经验。     

移动拟合法在煤层界面插值中的应用研究

为了在构建三维矿床模型过程中，形成最佳逼近的煤层界面模型，将移动拟合法引入到煤层界面插值中。根据煤层的赋存条件以及原始采样数据的分布特点提出了参数优化选择的有效方法及适用条件，并通过数学方法改善病态矩阵，使待估区域中的插值结果精度更高。以某矿的煤层界面数据为样本，通过交叉检验确定权函数，进行空间插值以及三维可视化，比较真实地反映了矿床的基本特征，为矿床地质模型的建立提供了有力的数据支撑。     

北京联合大学师范学院积极备战“2010年北京市大学生数学建模竞赛”

<正>为了迎接即将在开学初举行的"2010年北京市大学生数学建模竞赛",近日,北京联合大学师范学院团委、电气信息系、学生科学技术协会共同举办了学院数学建模参赛培训。     

可漫游的虚拟场景的建模与实现方法

随着虚拟现实技术的逐步成熟，其应用在近几年迅速发展，应用领域也有了很大的拓展，从最初的军事应用，拓展到教育艺术医疗以及最近到旅游等领域。构造可漫游的虚拟场景是虚拟现实中最基本的、必不可少的一个环节。本文从构造虚拟场景的一般步骤出发，阐述了三维建模的技术与方法，并在vrp平台上加以实现，生成了漫游场景，并达到了数字园林的预期效果。     

针孔SPECT成像完全三维图像重建的研究

依托自行研制的一台高分辨率小动物单光子发射型计算机体层成像系统(Micro- SPECT), 开发针孔SPECT成像的完全三维图像重建技术. 该研究包括: 针孔SPECT成像的投影算子推导及其在Radon空间的采样特性分析; 有效的系统几何参数校正方法; 适用于圆轨道和螺旋轨道扫描的三维图像重建算法及定量补偿方法的实现. 为验证开发的完全三维图像重建技术, 进行了相应的计算机模拟成像、模具成像及小鼠成像实验, 并对结果进行了讨论. 计算机模拟和模具及小鼠成像实验显示: 跟基于解析求逆理论的近似图像重建算法FDK相比, 基于统计理论的三维迭代图像重建算法结合有效的系统响应补偿方法, 能够显著地改善重建图像质量和提高系统成像分辨率; 螺旋轨道扫描的针孔SPECT成像技术可以有效地克服常规圆轨道扫描成像的局限性, 扩大成像系统的轴向视野, 提供相对完备的锥形束投影采样空间, 实现高分辨率的全身小动物SPECT成像. 实验结果表明我们开发的完全三维图像重建方法与技术是切实有效的, 达到了预期的目的, 可以较容易地推广应用于多针孔SPECT成像的三维图像重建.