Adaptive timeliness of consensus in presence of crash and timing faults

The Δ$\mathrm{\Delta }$-timed uniform consensus is a stronger variant of the traditional consensus and it satisfies the following additional property: every correct process terminates its execution within a constant time Δ$\mathrm{\Delta }$ (Δ$\mathrm{\Delta }$-timeliness), and no two processes decide differently (uniformity). In this paper, we consider the Δ$\mathrm{\Delta }$-timed uniform consensus problem in presence of _fc$f_{\mathrm{c}}$ crash processes and _ft$f_{\mathrm{t}}$ timing-faulty processes, and propose a Δ$\mathrm{\Delta }$-timed uniform consensus algorithm. The proposed algorithm is adaptive in the following sense: it solves the Δ$\mathrm{\Delta }$-timed uniform consensus when at least _ft+1$f_{\mathrm{t}}+1$ correct processes exist in the system. If the system has less than _ft+1$f_{\mathrm{t}}+1$ correct processes, the algorithm cannot solve the Δ$\mathrm{\Delta }$-timed uniform consensus. However, as long as _ft+1$f_{\mathrm{t}}+1$ processes are non-crashed, the algorithm solves (non-timed) uniform consensus. We also investigate the maximum number of faulty processes that can be tolerated. We show that any Δ$\mathrm{\Delta }$-timed uniform consensus algorithm tolerating up to _ft$f_{\mathrm{t}}$ timing-faulty processes requires that the system has at least _ft+1$f_{\mathrm{t}}+1$ correct processes. This impossibility result implies that the proposed algorithm attains the maximum resilience about the number of faulty processes. We also show that any Δ$\mathrm{\Delta }$-timed uniform consensus algorithm tolerating up to _ft$f_{\mathrm{t}}$ timing-faulty processes cannot solve the (non-timed) uniform consensus when the system has less than _ft+1$f_{\mathrm{t}}+1$ non-crashed processes. This impossibility result implies that our algorithm attains the maximum adaptiveness.     

浅谈分布式虚拟现实及其实时性研究

分布式虚拟现实系统简称DVR,是虚拟现实系统的一种类型,它是基于网络的虚拟环境。在这个环境中,位于不同物理环境位置的多个用户或多个虚拟环境通过网络相连接,或者多个用户同时参加一个虚拟现实环境,通过计算机与其他用户进行交互,并共享信息。在分布式虚拟现实系统中,多个q用户可通过网络对同一虚拟世界进行观察和操作,以达到协同工作的目的。简单地说是指一个支持多人实时通过网络进行交互的软件系统,每个用户在一个虚拟现实环境中,通过计算机与其它用户进行交互,并共享信息。     

基于价值优化的相控阵雷达任务调度算法

针对相控阵雷达时间资源分配问题,该文提出一种基于价值优化的任务调度算法。首先建立任务调度属性参数,对跟踪任务队列进行可行性分析和筛选操作,确定跟踪任务调度属性。其次,根据任务最大价值及其变化斜率,建立关于实际执行时刻的动态任务价值函数,并基于此构建任务调度的价值优化模型,对跟踪任务执行时刻进行分配,以更好满足及时性原则。最后,利用执行跟踪任务间的空闲时间片对搜索任务进行调度。仿真结果表明,该文算法有效减小了时间偏移量,提升了实现价值率。

     

等离子体处理对固态丙烯酸浆料性能的影响

研究等离子体处理对固态丙烯酸浆料性能的影响.通过测试固态丙烯酸处理前后浆料黏度、黏附性、浆膜断裂强力、浆膜断裂伸长率和浆膜吸湿性等性能的变化,分析了不同条件下等离子体处理对固态丙烯酸浆料的作用效果,并研究了放置时间与方式对经等离子体处理后固态丙烯酸浆料性能的影响.试验结果表明,等离子体处理使固态丙烯酸浆料性能得到了一定改善与提高,但改性的效果会随着放置时间的延长而减弱.     

Patent information in a changing world: Perspectives from a major patent office

The patent information field is in a state of flux, caused by new tools and changing habits and philosophies. In this article a number of major issues arising from this situation are discussed, some ways in which the EPO is responding are described, and some ideas on future developments provided.Patents are increasingly rated as valuable assets, but is patent information, and especially bibliographic patent information, being treated with the same meticulousness as in the past? More people are searching than ever before. But are they squeezing out the information professional? What effect will the IPC reform, the arrival of XML and other developments have? By focussing on completeness, timeliness and correctness, can patent offices make a contribution to alleviate the situation?The author concludes that, more than ever before, it is important that expert patent information professionals ensure that their views and needs are communicated to both initial data suppliers, mainly patent offices, and to commercial database suppliers and hosts.     

一种基于应用场景的便携式音频采录编传系统

首先说明了广播记者外出采访时对音频采录编传设备的使用现状和存在问题,然后根据实际调研结果提出了3种采访常见的应用场景,最后基于这些应用场景提出了一种的便携式音频采录编传系统,并从实际应用角度分析了该系统如何能够更好满足广播记者日常采访的需求.     

网络延迟对队决策的影响

分布式决策组织必须具有自适应变结构功能。然而,决策过程具有极强的时间限制,要求系统必须在有限的时间范围内作出响应。因此,对于及时性要求很高的系统来说,研究网络延迟对决策组织的输出的影响具有重大的理论和应用价值。从系统的功能结构和物理结构两个方面来分析决策组织结构,把物理结构上的时间延迟映射到功能结构中,利用着色Petri网来进行结构和性能的分析与预测。     

一种可靠的多方不可否认协议的逻辑分析方法

多方不可否认协议需要满足不可否认性、公平性和时限性三大安全目标,但是现有的对多方不可否认协议的形式化分析方法大多是对两方协议分析方法的简单扩展,单一方法不能完整覆盖所有的安全目标分析;同时,对单一安全目标的分析能力有限,分析结果不可靠。首先,综合比较现有的分析技术,选定SVO逻辑进行扩展,显式引入时间因素,给出对应的语法定义和时间演算公理。然后,对改进逻辑的语义模型进行介绍,并证明了逻辑系统的可靠性,使得改进后的逻辑系统支持对多方不可否认协议三大安全目标的分析。最后,选取一个典型的多方不可否认协议,分别对其时限性和公平性进行分析,发现了其中存在的时限性和公平性缺陷,并给出了对应的攻击方法。其中,公平性缺陷是首次被发现。     

移动网资源管理的需求分析及系统设计

首先说明了移动网资源管理对电信运营商的重要性,阐述了运营商在资源管理方面普遍存在的管理缺失或者不到位的问题。为了解决该问题,建立一套资源管理体系:规范化资源字段,依靠软件系统使资源与流程相结合实现动态管理,引入考核管理手段配合IT系统,保证资源的准确性、完整性和及时性,避免数据“孤岛”。     

国家水资源监控能力建设项目试运行指标研究与实践

试运行是检验项目成果,改善用户体验,提高系统效率的最后环节,是确保建成的系统以良好的功能性能状态,做好全面正式投入运行准备的关键环节。以试运行的工作组织和指标的研究设立为切入点,以取用水、水源地、水功能区、省界断面数据在水利部和流域及省级三级节点之间的贯通为重点,全面分析国家水资源监控能力建设项目(2012—2014年)试运行工作,为总体项目的最终验收提供参考。