Recent advances and future challenges for massive MIMO channel measurements and models大规模多输入多输出通信系统的信道测量与建模的最新进展及未来挑战

This paper considers a unicast multiuser multiple-input single-output (MISO) downlink system overheard by multiple single-antenna eavesdroppers. The objective is to jointly design the beamforming vectors and the artificial noise (AN) covariance matrix with imperfect channel state information (CSI) at the transmitter, such that the total transmit power is minimized while satisfying probabilistic quality of service (QoS) constraints at legitimate users and the eavesdroppers. Using Bernstein-type inequalities and the S-procedure, we recast the non-convex power minimization problem as two different convex semidefinite programs (SDPs) which can be solved using interior-point methods. Simulation results show that the proposed methods outperform a nonrobust method and the ones using the isotropic AN.     

A Two-Stage Approach for Network Monitoring

A goal of network tomography is to infer the status (e.g. delay) of congested links internal to a network, through end-to-end measurements at boundary nodes (end-hosts) via insertion of probe signals. Because (a) probing constitutes traffic overhead, and (b) in any typical scenario, the number of congested links is a small fraction of the total number in the network, a desirable design objective is to identify those (few) congested links using a minimum number of probes. In this paper, we make a contribution to solving this problem, by proposing a new two-stage approach for this problem. First, we develop a binary observation model linking end-to-end observations with individual link statuses and derive necessary and sufficient conditions for whether at least one link in the network is congested. Stage I of the proposed method shows that achieving 1-identifiability with a minimum number of probes is equivalent to the familiar minimum set covering problem that can be efficiently solved via a greedy heuristic. A sequential algorithm is described, leading to a significantly lowered computational complexity vis-a-vis a batch algorithm. Next, a binary splitting algorithm originally developed in group testing is used to identify the location of the congested links. The proposed scheme is evaluated by simulations in OPNET and experiments on the PlanetLab testbed to validate the advantages of our 2-stage approach vis-a-vis a conventional (batch) algorithm.     

Skeleton pruning as trade-off between skeleton simplicity and reconstruction error

The position and orientation of moving platform mainly depends on global positioning system and inertial navigation system in the field of low-altitude surveying, mapping and remote sensing and land-based mobile mapping system. However, GPS signal is unavailable in the application of deep space exploration and indoor robot control. In such circumstances, image-based methods are very important for self-position and orientation of moving platform. Therefore, this paper firstly introduces state of the art development of the image-based self-position and orientation method (ISPOM) for moving platform from the following aspects: 1) A comparison among major image-based methods (i.e., visual odometry, structure from motion, simultaneous localization and mapping) for position and orientation; 2) types of moving platform; 3) integration schemes of image sensor with other sensors; 4) calculation methodology and quantity of image sensors. Then, the paper proposes a new scheme of ISPOM for mobile robot — depending merely on image sensors. It takes the advantages of both monocular vision and stereo vision, and estimates the relative position and orientation of moving platform with high precision and high frequency. In a word, ISPOM will gradually speed from research to application, as well as play a vital role in deep space exploration and indoor robot control.     

杆塔倾角监测与报警系统的设计

分析杆塔的环境条件对杆塔倾角监测与报警系统提出的要求,采用太阳能电池板和蓄电池联合供电的方式,设计具有定时唤醒机制的两级MCU控制的集散控制中心,一级MCU以中断方式接收加速度计传感器采集的数据,二级MCU将数据转换成RS-485传输方式,经过光纤转换模块以光缆传输到指挥控制中心,实现了信息的可靠获取及传输;该系统体积小、成本低、微功耗、可靠性高、可维护性强,可用于各种环境的倾角指示和测量。     

篮球比赛记时记分器设计

以P89V51RB2单片机为核心结合ZLG7289B外围显示管理芯片,使用LED点阵和七段数码管共同进行显示,完成了记时与记分的功能;该装置可以显示当前节次,比赛剩余时间,双方比分,并能够根据实际情况对比赛的时间及分数进行修改。     

Static Bayesian games with finite fuzzy types and the existence of equilibrium

This paper studies a special game with incomplete information, in which the payoffs of the players are both random and fuzzy. Such a game is considered in the context of a Bayesian game with the uncertain types characterized as fuzzy variables. A static fuzzy Bayesian game is then introduced and the decision rules for players are given based on credibility theory. We further prove the existence of the equilibrium of the game. Finally, a Cournot competition model with fuzzy efficiency under asymmetric information is investigated as an application and some results are presented.     

Parallel block tridiagonalization of real symmetric matrices

Two parallel block tridiagonalization algorithms and implementations for dense real symmetric matrices are presented. Block tridiagonalization is a critical pre-processing step for the block tridiagonal divide-and-conquer algorithm for computing eigensystems and is useful for many algorithms desiring the efficiencies of block structure in matrices. For an “effectively” sparse matrix, which frequently results from applications with strong locality properties, a heuristic parallel algorithm is used to transform it into a block tridiagonal matrix such that the eigenvalue errors remain bounded by some prescribed accuracy tolerance. For a dense matrix without any usable structure, orthogonal transformations are used to reduce it to block tridiagonal form using mostly level 3 BLAS operations. Numerical experiments show that block tridiagonal structure obtained from this algorithm directly affects the computational complexity of the parallel block tridiagonal divide-and-conquer eigensolver. Reduction to block tridiagonal form provides significantly lower execution times, as well as memory traffic and communication cost, over the traditional reduction to tridiagonal form for eigensystem computations.     

基于Lucene/Heritrix的垂直搜索引擎的研究与应用

Lucene是一个用Java写的全文索引引擎工具包,访问索引时间快,支持多用户访问,可以跨平台使用.Heritrix是一个由Java开发的、开源的Web网络爬虫,用户可以使用它从网络上抓取想要的资源.探讨了Lucene和Heritrix在构建垂直搜索引擎中的应用.     

德化陶瓷虚拟展厅

讨论了虚拟现实技术用于陶瓷展示的可行性,关键技术和系统的实现过程.利用3DSMAX和PhotoShop建立展厅和瓷器的三维模型,并使用贴图技术增强瓷器模型的真实感;使用开源的图形渲染引擎0GRE实现场景资源的组织和管理,并基于OGRE实现了虚拟展厅的实时交互和动态漫游功能.     

基于间歇控制的不确定主从Lur’e系统的指数同步

研究了不确定主从Lur’e系统的问歇控制同步问题．运用Lyapunov稳定性理论和S-过程,首先推导出保证标称主从Lur’e系统指数同步的一个充分条件．在此基础上进一步得到了具有范数有界不确定性主从Lur’e系统鲁棒指数同步的结果．这些同步判据以矩阵不等式的形式给出．另外我们还提出了一种最小化性能指标的优化策略．最后,通过两个数值例子验证了结果的有效性．