The State of the Art in Text Filtering

This paper develops a conceptual framework for text filtering practice and research, and reviews present practice in the field. Text filtering is an information seeking process in which documents are selected from a dynamic text stream to satisfy a relatively stable and specific information need. A model of the information seeking process is introduced and specialized to define text filtering. The historical development of text filtering is then reviewed and case studies of recent work are used to highlight important design characteristics of modern text filtering systems. User modeling techniques drawn from information retrieval, recommender systems, machine learning and other fields are described. The paper concludes with observations on the present state of the art and implications for future research on text filtering. This revised version was published online in July 2006 with corrections to the Cover Date.     

VPRN成员信息传播方法及比较

1 引言 IP VPN可以定义为采用IP设施(包括公共Internet网和专用IP主干网)模拟专用广域网设施,因其既有专用网络的可靠性,又不需要专用网络的投资,而且灵活多变而越来越受到网络厂商和用户的青睐。IP VPN可分为虚拟租用线、虚拟专用路由网(VPRN)和虚拟专用拨号网等类型。其中VPRN最为复杂,应用于多点路由器连接构成的VPN。     

Efficient data dissemination using locale covers

Location-dependent data are central to many emerging applications, ranging from traffic information services to sensor networks. The standard pull- and push-based data dissemination models become unworkable since the data volumes and number of clients are high.We address this problem using locale covers, a subset of the original set of locations of interest, chosen to include at least one location in a suitably defined neighborhood of any client. Since location-dependent values are highly correlated with location, a query can be answered using a location close to the query point. Typical closeness measures might be Euclidean distance, or a $k$-nearest neighbor criterion.We show that location-dependent queries may be answered satisfactorily using locale covers. Our approach is independent of locations and speeds of clients, and is applicable to mobile clients.We also introduce a nested locale cover scheme that ensures fair access latencies, and allows clients to refine the accuracy of their information over time. We also prove two important results: one regarding the greedy algorithm for sensor covers and the other pertaining to randomized locale covers for $k$-nearest neighbor queries.     

Trust and reputation management for opportunistic dissemination

Nodes in opportunistic networks need to cooperate to disseminate data. However, employing intermediate nodes for dissemination leads to several security issues. Here, we propose an opportunistic trust and reputation mechanism entitled SAROS, which detects and avoids malicious nodes, i.e. nodes which, upon receiving messages for other interested peers, modify their content in order to spread false information. This can negatively affect the network, by polluting it with spam messages, or dropping messages of interest to the nodes in the network. By detecting and avoiding malicious nodes, SAROS is able to increase the percentage of correct messages that reach their destinations.     

齐大山铁矿石的工艺矿物学特征研究

随着齐大山铁矿开采深度的增加 ,矿石工艺矿物学特征正发生较大变化 ,对选矿生产产生一定影响。通过对齐大山现开采矿石的工艺矿物学研究 ,阐述了齐大山现开采矿石变化的新特点 ,并对如何改进选矿生产提出了相应的建议     

山东某铁矿选矿试验

山东某低铁高硅含硫铁矿石中各矿物嵌布粒度差异较大,磁铁矿、赤褐铁矿含量相当,赤褐铁矿与石英嵌布关系较复杂,属典型的难选铁矿石。试验研究表明,磨矿-脱硫浮选-弱磁选-弱磁尾再磨-强磁选-强磁精矿脱硅反浮选流程是处理该矿石的高效流程,最终获得了铁品位为65.26%、含硫0.18%、含SiO₂ 5.41%、铁回收率为82.99%的铁精矿,以及含硫25.56%、硫回收率为68.89%的硫精矿。     

延时容忍网络中基于内容的信息传播机制研究

延时容忍网络(Delay-tolerant Network)是一种实用的受限网络模型,它具有延迟长、网络分割、节点能力受限等特点.在这种网络环境下,由于网络拓扑不断变化,节点间端到端的通信路径并不存在,传统的路由协议无法有效的运作.针对延时容忍网络的特点,提出了一种基于内容的信息传播机制.在该机制中,每个节点根据相遇历史信息决定是否对所获得的信息进行转发.实验结果表明,该信息传播机制在通信延迟和信息开销方面,较传统OCBD协议和Epidemic协议有所提升.     

冀东豆子沟铁矿石工艺矿物学特征

冀东豆子沟铁矿石铁品位为35.80%,铁主要以磁铁矿形式存在,其次为赤铁矿、碳酸铁,脉石矿物主要为石英、角闪石和辉石。为给该矿石开发利用提供依据,对其进行了工艺矿物学分析。结果表明:矿石结构主要为半自形—他形晶粒状结构,其次为自形晶粒结构、压碎结构、交代残留结构。矿石构造以条纹状和条带状构造为主,其次为片麻状构造。磁铁矿主要呈半自形—他形粒状赋存于石英等脉石矿物中,少数呈八面体型或立方体型赋存于石英或角闪石等脉石矿物中。矿石中磁铁矿嵌布粒度微细,64.01%的磁铁矿分布在0.02~0.16 mm粒级,12.59%分布在-0.02 mm粒级,这部分磁铁矿需细磨才能实现单体解离,但细磨容易造成泥化影响选矿指标,故建议采用阶段磨矿阶段选别工艺。     

体育动漫对我国青少年体育兴趣的影响研究

探讨我国体育动漫作品的特点以及由这些特点所衍生出来的传播效果的问题,从理论角度诠释这些动漫作品对我国青少年在体育兴趣的培养受到的影响,给予我国动漫人和教育者一些思考与启发。     

以市场为主体 开展节能宣传工作

该文回顾了国家经贸委节能信息传播中心成立四年来所做的工作,对中心制作的部分案例的使用效果作了介绍。指出节约能源对经济的发展、企业产品成本的降低起着重要作用。