融合多源日志辅助取证的事件场景关联方法

计算机取证牵涉的证据通常分布在多种不同的日志中,从多源日志进行事件场景关联对于辅助取证意义 重大。提出了一种融合多源日志的基于事件“前提/结果”因果关系的事件场景关联方法。首先用基于IDMEF格 式的数据模型表示来自多源日志的安全事件,再通过预先定义的事件“前提/结果”知识将这些事件关联成事件场 景。实验表明该文提出的方法可辅助取证人员自动关联多源日志信息,生成可视化的事件关联图。     

基于演化博弈的重大突发公共卫生事件情景预测模型与防控措施

运用演化博弈理论建立了重大突发公共卫生事件的疫情传播方程, 将政府部门和社会公众的策略互动和行为演化分析融入到传染病自然传播的SI模型. 根据卫生部公布甲型H1N1流感疫情每日新增确诊病例数, 在三种演化情景下(即疫情大规模扩散、疫情迅速得到控制、当前的政府积极防控策略), 对疫情传播初期阶段进行了Logistic方程拟合和疫情传播峰值点的预测分析. 最后, 提出了重大疫情初期阶段"谨慎性"防控原则、随着疫情进展及时调整防控策略的"灵活性"原则、选择调整时机的主要考虑因素. 根据疫情传播方程, 讨论了政府调整甲型H1N1疫情控策略对疫情传播的影响.     

基于全球模式对中国21世纪夏季高温的变化预估

根据12个全球气候系统模式(GCM)3种排放情景(A2,A1B和B1)下对中国地区21世纪近100 a的夏季平均气温的模拟值,以1971—2000年为基准,计算并分析了该区域未来夏季高温的变化趋势.不同排放情景下各模式的模拟结果不同,且各模式对夏季高温模拟的差异大于对异常高温的模拟.就模式平均而言,A2情景下高温日数最多,A1B次之,B1情景下最少.增长趋势也是A2情景下最快为6.0 d.(100 a)-1,A1B和B1情景分别为5.4和3.4 d.(100 a)-1.对异常高温频次的模拟,B1情景下异常高温频次最多,为8.8 d.a-1,A1B和A2情景下均为8.7 d.a-1,三者之间差距很小.A2情景下异常高温频次增长最快,增长趋势为2.6 d.(100 a)-1,A1B情景下增长略慢,为1.9 d.(100 a)-1,B1情景下增长最慢,仅为1.5 d.(100 a)-1.对3种情景下各模式对高温日数的模拟能力进行了分析,从多方面比较了各模式的模拟能力.     

基于概率情景的多场点系统地震风险分析方法

该文针对传统地震危险性分析方法面向多场点系统(诸如某一区域内多个建筑、某个基础设施网络)整体地震风险计算时的局限性,提出了基于概率场景的多场点地震风险分析方法。该方法首先结合地震潜在震源的震级概率分布函数以及地震动预测公式,并考虑地震动空间相关性模型,通过随机模拟生成大量的概率地震情景(地震动分布图),在地震情景集及相应概率信息的基础上对一些典型的多场点系统,例如独立多场点系统、串联多场点系统、并联多场点系统等进行了系统风险分析。并通过对比分析单场点与多场点系统的地震风险,对比分析考虑和不考虑地震动估计误差空间相关性两种情况下的多场点系统地震风险,最终得出了三种类型多场点系统地震风险表现的不同特征。结果表明:不考虑空间相关性会导致独立多场点系统高估低水平损失的概率、低估高水平损失的概率;会导致串联系统风险估计整体偏高;会导致并联系统风险估计整体偏低。     

基于交叉协方差子空间估计的前景检测方法

提出了一种基于交叉协方差子空间估计的背景建模方法,用以实现复杂场景下的前景检测.基于交叉协方差的主成分分析方法可以保留更多的图像协方差信息,因此非常适合用于背景模型的构建.本文首次将基于交叉协方差的二维主成分分析方法引入至背景建模领域,并且提出了相应的增量更新算法来实现背景的自适应估计.此外,本文考虑了前景的稀疏性及连续性,并将其合理应用于前景检测过程中.定量实验和定性分析表明,本文提出的方法具有较强的鲁棒性,可以实现复杂场景下的准确背景建模.      

基于射线跟踪法的隧道无线信道特性

城市地下轨道交通的隧道环境与地上环境的移动通信有显著不同,为发展应用于隧道环境中的无线通信系统,需要对隧道中的无线信道特性进行研究.本文使用射线跟踪法对隧道环境无线信道进行仿真,并将仿真结果与实际测量结果进行对比,对比结果表明:基于射线跟踪法的信道模型,能够较准确地预测隧道中的大尺度衰落和信道冲激响应等信道特性.在此基础上,又对隧道中的MIMO(多输入多输出天线)系统信道特性进行仿真,仿真结果得出结论:隧道环境中MIMO空间相关度在天线阵列方向上显示出波动性,波动周期与传播信号的波长成正比.     

Your Vision or My Model? Lessons from Participatory Land Use Scenario Development on a European Scale

Participatory processes in scenario development have received increasing attention throughout the last years. Combining qualitative stakeholder and quantitative expert information (i.e. modelling) offers unique opportunities to mix good data, scientific rigour, imagination and expertise from different perspectives. However, this task is all but easy as it requires a careful balancing of approaches and an acceptance of different levels of knowledge and trust in different methods across disciplinary boundaries. In spite of a growing body of literature we are still in the early stages of learning how to deal effectively with participatory scenario development. In the PRELUDE project of the European Environment Agency a relatively far-reaching participatory approach to scenario development was applied: a group of stakeholders from across Europe was given full responsibility to develop long-term alternative land use scenarios in cooperation with experts and modellers. The scenarios have been used in a formal outreach process with key clients and stakeholders at the European and Member State level afterwards. The aim of this paper is to document the methods used, analyse their strengths and weaknesses and draw some general conclusions regarding participatory processes in scenario development. This paper argues that in future scenario development more attention needs to be paid to strengthen the integration of qualitative and quantitative analysis. A set of compelling and coherent storylines can effectively trigger strategic conversations among policy-makers and key stakeholders about potential future developments and related response strategies. A weak integration with quantitative results can undermine this outcome, which is one of the ultimate objectives of any scenario exercise.

基于相机的可见光通信技术

 可见光通信（VLC）有效结合了发光二极管（LED）的绿色照明和通信两大优点,是无线光通信的研究热点之一。基于相机VLC系统（简称OCC系统）在智能手机越来越普及的潮流下受到了广泛的关注和研究。OCC系统以照明LED为信号光源而以相机中图像传感器（IS）为信号接收器件,具有天然空间分集接收能力,因此具有广泛的应用前景。由于IS与传统光电二极管（PD）在可见光信号的接收与处理过程有明显不同,原有基于PD的VLC相关通信技术无法直接应用于基于IS的VLC系统。本文阐述了OCC系统的关键技术,并给出了相关应用场景。     

Simulation and uniform design-based automatic generation of risk scenarios

This paper presents a methodology for automatically generating risk scenarios for dynamic reliability applications in which some dynamic characteristics(e.g.,the order,timing and magnitude of events,the value of relevant process parameters and initial conditions) have a significant influence on the evolution of the system.The main idea of the methodology is:(i) making the system model "express itself" through simulation by having the model driven by an elaborated simulation engine;(ii) exploiting uniform design to pick out a small subset of representative design points from the space of relevant dynamic characteristics;(iii) for each selected design point,employing a depth-first systematic exploration strategy to cover all possible scenario branches at each branch point.A highly dynamic example adapted from the literature(a chemical batch reactor) is studied to test the effectiveness of the proposed methodology.     

Application of MIGP in Phosphate Rock Districts Development Planning and System Economic Evaluation

This paper, based on the study results of a subproject under the Seventh Fiveyear-plan National Major Scientific and Technological Research Project, will concentrate on the application of the mixed integer goal programming in the studies on the optimization and comprehensive evaluation of investment decision and production planning in Yichang phosphate rock district in Hubei Province and in Dianchi district in Yunnan Province. The optimization models for mineral district development planning system are formulated through system analysis. A microcomputer software based on the combination of mixed integer programming and goal programming is developed to continuously implement the calculation for the mathematical model with arbitrary objective priority levels and for a group of such models. And a system economic evaluation model is developed to measure the profitability of optimal planning system scenarios. Finally, a large amount of output information are provided for the reference of decision makers.