An adaptive interference alignment scheme based on the dynamic selection of desired transmitters for unmanned ship network

Wireless Networks - In the unmanned ship networking scenario, the position of the unmanned ship changes continuously, leading to the result that the desired transmitters and the interference...     

A rough set approach to feature selection based on power set tree

Feature selection is viewed as an important preprocessing step for pattern recognition, machine learning and data mining. Traditional hill-climbing search approaches to feature selection have difficulties to find optimal reducts. And the current stochastic search strategies, such as GA, ACO and PSO, provide a more robust solution but at the expense of increased computational effort. It is necessary to investigate fast and effective search algorithms. Rough set theory provides a mathematical tool to discover data dependencies and reduce the number of features contained in a dataset by purely structural methods. In this paper, we define a structure called power set tree (PS-tree), which is an order tree representing the power set, and each possible reduct is mapped to a node of the tree. Then, we present a rough set approach to feature selection based on PS-tree. Two kinds of pruning rules for PS-tree are given. And two novel feature selection algorithms based on PS-tree are also given. Experiment results demonstrate that our algorithms are effective and efficient.     

Industrial architectural assessment using TARA

Scenario based architectural assessment is a well-established approach for assessing architectural designs. However scenario-based methods are not always usable in an industrial context, where in our experience, they can be perceived as complicated and expensive to use. In this paper we explore why this may be the case and define a simpler technique called TARA, which has been designed for use in situations where scenario based methods are unlikely to be successful. The method is illustrated through an experience report that explains how it was applied to the assessment of two quantitative financial analysis systems, and its strengths, weaknesses and relationship to other methods are briefly discussed.     

A π-extended tetrathiafulvene derivative: Synthesis and photoluminescence properties

Solid-state emissive organic materials have received increasing attention due to their prospective applications in large-area. Here, a novel π-extended tetrathiafulvene derivative DPD with donor-π-donor structure has been newly developed to produce the prominent characteristic of aggregation-induced enhanced emission (AIEE) that exhibits higher fluorescence quantum efficiency in solid film compare to its solutions. The AIEE mechanism of DPD was studied in detail through photophysical investigations and can be dominant attributed to the formed excimer state of DPD and J-aggregates in solid state.     

基于以太网的宿舍楼字网络规划

以太网适合于小型局域网,特别适合上网集中和用户数目多的高校局域网,提出一种基于以太网的宿舍楼宇网络规划,就其物理链路中的布线相关要求做了探讨,就管理网络和用户网络的Vlan、IP规划和安排等做阐述,最后给出网络拓扑图和网络规划具体实施流程。     

一种低成本城市停车诱导系统中区域性Zigbee网络的设计

为降低城市级停车诱导系统的建设、运营成本,提出一种无需建立管理控制中心的系统架构,采用LPC11C14和CC2530作为核心芯片设计了系统中的重要组成部分——区域性Zigbee网络。通过所开发出的测试系统的实验,表明该Zigbee网络可准确接收用户手机发出的停车请求,并能根据停车场内车位状态向用户反馈最佳车位信息,从用户发送请求到收到反馈信息的时间不超过10s。     

低渗透油藏水力压裂井应力场转向定量评价

基于多孔介质流-固耦合理论和有效应力定律,建立了孔隙压力与地应力相互作用的低渗透油藏水力压裂井应力场转向评价模型,采用有限元数值模拟技术并开发相应程序对耦合模型进行求解,定量分析了低渗透油藏开发过程中水力裂缝附近区域地应力场的变化特征.计算结果表明:水力裂缝导致近裂缝区域地应力场分布特征大幅度改变,沿裂缝与垂直裂缝方向应力场大小变化各向异性,应力场转向范围随初始水力裂缝长度增加而动态变化.     

The effect of pore necking on Knudsen diffusivity and collision frequency of gas molecules with pore walls

Straight pores whose walls were concave (for “Swiss cheese” type solids), convex (for “cannonball” type), or cylindrical (for capillary type) were simulated by computer. The pores having concave and convex walls were represented as an assemblage of spherical elements since any pore could be described merely by listing the radii and coordinates of the elements. Using a Monte Carlo method, molecular trajectories of gas molecules inside the pores were computed in the Knudsen regime to obtain the diffusivities, collision numbers and collision densities. These parameters were strongly dependent on the pore wall configuration. An equation was presented which enabled the prediction of Knudsen diffusivity from the mean pore size d̄ and (d_n/d_w)² (where d_n and d_w are the diameters of narrow and wide sections inside the pores, respectively). The average number of collisions per molecule J̄ was also correlated quite well with the ratio of geometric diffusion length to mean pore size L₀/d̄ for each type and was in the order capillary type > Swiss cheese type > cannonball type. It was found that the pore of capillary type had the preferred wall configuration among these three types from the view point of diffusivity and collision numbers of molecules. The results obtained here will have application to the design of micro- and macro-pore structures of supported catalysts.