一种简单路由算法下的全互连立方体网络性能分析

本文研究在一种简单路由算法条件下全互连立方体网络(FCCN，Fully Connected Cubic Network)的性能。研究结果表明在应用简单路由算法的条件下，至少在80％以上的情况下可以得到最短路径，而且这个比例是随着网络规模的扩大而增大的，进而得到网络最大结点间距离和平均结点距离的公式，而且网络性能在通信局部性的条件下可以显著提高。计算结果证明FCCN在信息局部性系统中具有比较高的并行处理效率。     

Approximate importance sampling Monte Carlo for data assimilation

Importance sampling Monte Carlo offers powerful approaches to approximating Bayesian updating in sequential problems. Specific classes of such approaches are known as particle filters. These procedures rely on the simulation of samples or ensembles of the unknown quantities and the calculation of associated weights for the ensemble members. As time evolves and/or when applied in high-dimensional settings, such as those of interest in many data assimilation problems, these weights typically display undesirable features. The key difficulty involves a collapse toward approximate distributions concentrating virtually all of their probability on an implausibly few ensemble members.

After reviewing ensembling, Monte Carlo, importance sampling and particle filters, we present some approximations intended to moderate the problem of collapsing weights. The motivations for these suggestions are combinations of (i) the idea that key dynamical behavior in many systems actually takes place on a low dimensional manifold, and (ii) notions of statistical dimension reduction. We illustrate our suggestions in a problem of inference for ocean surface winds and atmospheric pressure. Real observational data are used.     

Hierarchical condensation near phase equilibrium

A novel mechanism of new phase formation is studied both experimentally and theoretically in the example of quasi-equilibrium stationary condensation in an ion–plasma sputterer. Copper condensates are obtained to demonstrate that a specific network structure is formed as a result of self-assembly in the course of deposition. The fractal pattern related is inherent in the phenomena of diffusion limited aggregation. Condensate nuclei are shown to form statistical ensemble of hierarchically subordinated objects distributed in ultrametric space. The Langevin equation and the Fokker–Planck equation related are found to describe stationary distribution of thermodynamic potential variations at condensation. Time dependence of the formation probability of branching structures is found to clarify the experimental situation.     

On the motif distribution in random block-hierarchical networks

The distribution of motifs in random hierarchical topological networks defined by nonsymmetric random block-hierarchical adjacency matrices, is constructed for the first time. According to the classification of U. Alon et al. of network superfamilies (Milo et al., 2004 [11]) by their motifs distributions, our artificial directed random hierarchical networks fall into the superfamily of natural networks to which the neuron networks belong. This is the first example of a class of “handmade” topological networks with the motifs distribution as in a special class of natural networks of essential biological importance.     

单片式彩色LCOS微显芯片电路设计

介绍一种单片式彩色LCOS微显芯片的电路设计。这种LCOS芯片配置合适的光机及电路系统可用于单片式LCOS彩色背投电视或其它投影产品。与传统场序彩色LCOS微显芯片类似，该芯片的主要模块由行扫描驱动器、数据驱动器和象素驱动矩阵三大部分组成。不同的是二者的行寻址方式不同，传统场序彩色LCOS采用的是逐行扫描法，而此处介绍的彩色LCOS采用的是随机寻址方式，将红、绿、蓝三种数据几乎同时写入象素矩阵，配合滚动的光照显示彩色图像。单片式LCOS系统与三片式LCOS系统相比可以节省微显芯片及配套电路系统数目，从而大大节约成本，在背投电视和其他投影产品产业中有很大的实用价值。     

Bayesian compressive sensing for cluster structured sparse signals

In traditional framework of compressive sensing (CS), only sparse prior on the property of signals in time or frequency domain is adopted to guarantee the exact inverse recovery. Other than sparse prior, structures on the sparse pattern of the signal have also been used as an additional prior, called model-based compressive sensing, such as clustered structure and tree structure on wavelet coefficients. In this paper, the cluster structured sparse signals are investigated. Under the framework of Bayesian compressive sensing, a hierarchical Bayesian model is employed to model both the sparse prior and cluster prior, then Markov Chain Monte Carlo (MCMC) sampling is implemented for the inference. Unlike the state-of-the-art algorithms which are also taking into account the cluster prior, the proposed algorithm solves the inverse problem automatically—prior information on the number of clusters and the size of each cluster is unknown. The experimental results show that the proposed algorithm outperforms many state-of-the-art algorithms.     

BBU基带池集中设置的探讨和建议

针对底层网络的特点,分析BBU＋RRU站点集中化建设的优缺点,给出了集中化建设“分片、选点、保障”的新思路,并总结了BBU集中化建设的工程经验,提出了建设建议。     

Dynamic Host-Group/Multi-Destination Routing for Multicast Sessions

Multicast routing research efforts have mostly focused on supporting the host-group model in which multicast packets are addressed to a host (or multicast) group. Another multicast routing approach uses multi-destination addressing, where a multicast packet carries a list of the unique (unicast) addresses of all the group members. This form of routing can be accomplished using limited or no additional state beyond the existing unicast routing tables. It, therefore, scales well with the number of multicast sessions but does not scale well with the size of the multicast group and, in fact, requires the size of the multicast group to be below a certain threshold. In this paper, we envision a future scenario in which both host-group and multi-destination addressing routing approaches coexist within the Internet. We develop a dynamic routing context for this future scenario wherein a multicast session can adapt among different routing configurations depending on the number of multicast group members and how this number changes over time. We consider three routing options: (1) A single multi-destination addressed flow – suitable for small-group sessions, (2) multiple multi-destination addressed flows – suitable for medium-group sessions and (3) a single host-group addressed flow – suitable for large-group sessions. For multicast sessions that vary in group membership over time, different routing protocols may be best at different points in time. Our work is concerned with the development and evaluation of protocols that allow a multicast session to dynamically switch among these three routing options as the size of the session changes.