Optimizing content placement in a peer-assisted VoD architecture

Recently, a new peer-assisted architecture to build content delivery systems has been presented. This architecture is based on the use of the storage capacity of end-users’ set-top boxes (STBs), connected in a peer-to-peer (P2P) manner in order to help the content servers in the delivery process. In these systems, the contents are usually split into a set of smaller pieces, called sub-streams, which are randomly injected at the STBs. The present paper is focused on Video on Demand (VoD) streaming and it is assumed that the STB-based content delivery system is deployed over the global Internet, where the clients are distributed over different ISP networks. In this scenario, three different strategies are studied for increasing the percentage of data uploaded by peers, in order to offload the content servers as much as possible. First of all, a new mechanism is presented which determines which sub-stream has to be placed at which STB by a Non-Linear Programming (NLP) formulation. A different strategy for reducing the content server load is to take advantage of the available bandwidth in the different ISP networks. In this sense, two new mechanisms for forwarding the VoD requests to different ISP networks are presented. Finally, the present paper also shows that in some situations the available uplink bandwidth is associated with STBs that do not have the required sub-streams. Regarding this concern, a new mechanism has been designed that dynamically re-allocates some streams, which are being transmitted from specific STBs, to different STBs, in order to find the necessary resources to start new streaming sessions.     

A kernel-based framework for image collection exploration

While search engines have been a successful tool to search text information, image search systems still face challenges. The keyword-based query paradigm used to search in image collection systems, which has been successful in text retrieval, may not be useful in scenarios where the user does not have the precise way to express a visual query. Image collection exploration is a new paradigm where users interact with the image collection to discover useful and relevant pictures. This paper proposes a framework for the construction of an image collection exploration system based on kernel methods, which offers a mathematically strong basis to address each stage of an image collection exploration system: image representation, summarization, visualization and interaction. In particular, our approach emphasizes a semantic representation of images using kernel functions, which can be seamlessly harnessed across all system components. Experiments were conducted with real users to verify the effectiveness and efficiency of the proposed strategy.     

淮北平原主要农作物涝渍灾害 损失评估研究

针对淮北平原除涝减灾综合治理与规划中缺乏主要农作物受涝损失调查与评估基础资料的实 际问题,于2010年9月初区域降雨成灾之际,对受涝区进行主要农作物受涝经济损失调查。依据实 地调研成果,通过综合统计分析推求了不同耕地类型不同暴雨强度下的受涝损失率,在此基础上实现 了对淮北平原受涝经济损失的合理评估。     

浅析电子商务中的安全问题

随着现今社会互联网、个人终端技术的飞越发展,电子商务越来越多的出现在人们的生活与工作中,这种全新的商务模式具有便捷、高效率、低成本的特点.同时,这种全新的商务模式对管理水平、信息传递技术都提出了更高的要求,其中安全的重要性尤为突出.     

高性能计算中处理器功耗特征的评测与分析

高性能计算系统的系统结构和应用模式与单机系统或商用机群服务器系统都有很大的不同,掌握功耗特征是提高能效的前提。本文将支撑功耗管理的低功耗技术分为动态资源休眠和动态速率调节两类,并就处理器的这两类机制在高性能计算中的应用进行评测,验证了功耗管理在高性能计算中的有效性,量化分析了处理器功耗特征,指出了当前管理方案的不足及改进设想,对进一步能耗优化有重要的指导意义。     

多角色需求评审系统的设计与实现

需求质量对于软件产品质量有至关重要的影响,而需求评审是保证需求质量的有效手段之一.目前的需求评审存在效率低、问题发现率不高、评审结果难以被有效处理等问题.在对需求特性进行研究,以及对实际项目中人员角色及其关注点进行调研的基础上,开发了多角色的需求评审系统MRRS.MRRS系统为每类角色的评审人员提供有针对性的评审指标体系,依照预设算法对评审结果进行量化处理,以GUl形式展示结果,为项目决策提供支持.应用了MRRS系统后,评审效率提高一倍以上.     

需求变更管理过程及其工具分析与展望

对软件开发中的需求变更的产生原因及对项目的影响做了分析和讨论,介绍和研究了不同方法学中对于需求变更管理的要求和处理过程,并对这些主流的方法学中的变更管理过程做了一些总结和比较.对需求变更管理工具应该提供的功能做了一些讨论,比较了部分主流的需求管理工具中的变更管理功能,最后对软件需求管理工具的未来的发展方向进行了展望.     

求解弹头散布均匀度的分布估计算法

未来空域窗射击体制是一种新型的高炮射击体制, 这种射击体制对近程防空反导具有显著的效果. 在对未来空域窗进行设计和评价时, 必须计算未来空域窗内弹头散布的均匀度, 并要求算法具有全局收敛以及解的精度高. 文章描述了未来空域窗弹头散布均匀度的问题, 提出了一种求解弹头散布均匀度的分布估计算法; 然后, 提出了一种变焦算法用来提高算法的搜索效率和解的精度, 并给出了混合算法的流程图. 仿真结果表明, 混合算法具有全局收敛、解的精度高以及搜索效率高的优点, 适合于在实际工程中用来求解弹头散布均匀度.     

卷草纹的艺术语言及其现代延展设计

卷草纹是中国传统装饰纹样之一,它的形成和发展记载了中国装饰艺术旺盛的生命力。本文分析了卷草纹的发展过程、形象构成以及艺术特征,并通过具体案例诠释了它在现代设计各个领域的延展和应用。旨在探索传统装饰纹样在现代设计中的传承与发展的方向。     

P2P网具有QoS保障的语义Web服务匹配方法

在P2P网络中,有大量的web服务,如何准确高效的发现零散分布于世界各地的语义Web服务呢？文章从P2P网络的特点出发,分析了现有的一些研究和方法,在扩展UDDI的基础上,结合目前语义Web服务匹配的多层匹配思想,提出了P2P网络中支持QoS的语义Web服务匹配和发现的有效方法。该方法采用一个四层次的匹配筛选算法,对QoS各层的匹配算法进行了深入讨论,并以相似函数来度量服务提供方与服务请求方的Web服务相似程度。