基于时空数据的驻留行为特征可视分析

随着智慧城市的快速发展,大量商业场所每天会产生海量的驻留行为数据,然而传统驻留行为数据分析方法难以克服数据稀疏性问题,并且对于时空伴随关系的发现准确度也较低。根据驻留行为数据特征和可视分析任务,设计一种交互式的可视分析系统。对原始数据进行处理,提取相关的时空特征并发现用户伴随关系。使用改进的可变滑动窗口算法,并结合可视分析技术,设计用户关系图、时间甘特图、多变量表达的示意性地图、径向条形图、日历热力图等多种视图,实现对驻留场所的流量分布、用户来源等特征的多时段可视分析。应用两个真实数据集进行案例分析,并对发现的行为模式及对应现象进行解释说明,证明了该系统的可用性和拓展性,并表明其可实现团体出行特征和场所流量分析等系统级应用,为相关经营性商业场所提供合理化建议及辅助决策支持。     

Dynamic Visual Abstraction of Soccer Movement

Trajectory‐based visualization of coordinated movement data within a bounded area, such as player and ball movement within a soccer pitch, can easily result in visual crossings, overplotting, and clutter. Trajectory abstraction can help to cope with these issues, but it is a challenging problem to select the right level of abstraction (LoA) for a given data set and analysis task. We present a novel dynamic approach that combines trajectory simplification and clustering techniques with the goal to support interpretation and understanding of movement patterns. Our technique provides smooth transitions between different abstraction types that can be computed dynamically and on‐the‐fly. This enables the analyst to effectively navigate and explore the space of possible abstractions in large trajectory data sets. Additionally, we provide a proof of concept for supporting the analyst in determining the LoA semi‐automatically with a recommender system. Our approach is illustrated and evaluated by case studies, quantitative measures, and expert feedback. We further demonstrate that it allows analysts to solve a variety of analysis tasks in the domain of soccer.     

语义增强的大规模多元图简化可视分析方法

网络图可视化可以有效展示网络节点之间的连接关系,广泛应用于诸多领域,如社交网络、知识图谱、生物基因网络等.随着网络数据规模的不断增加,如何简化表达大规模网络图结构已成为图可视化领域中的研究热点.经典的网络图简化可视化方法主要包括图采样、边绑定和图聚类等技术,在减少大量点线交叉造成的视觉紊乱的基础上,提高用户对大规模网络结构的探索和认知效率.然而,上述方法主要侧重于网络图中的拓扑结构,却较少考虑和利用多元图节点的多维属性特征,难以有效提取和表达语义信息,从而无法帮助用户理解大规模多元网络的拓扑结构与多维属性之间的内在关联,为大规模多元图的认知和理解带来困难.因此,本文提出一种语义增强的大规模多元图简化可视分析方法,首先在基于模块度的图聚类算法基础上提取出网络图的层次结构;其次通过多维属性信息熵的计算和比较分析,对网络层次结构进行自适应划分,筛选出具有最优属性聚集特征的社团;进而设计交互便捷的多个关联视图来展示社团之间的拓扑结构、层次关系和属性分布,从不同角度帮助用户分析多维属性在社团形成和网络演化中的作用.大量实验结果表明,本文方法能够有效简化大规模多元图的视觉表达,可以快速分析不同应用领域大规模多元图的关联结构与语义构成,具有较强的实用性.     

无线传感器网络环境下时-空查询处理方法

在无线传感器网络环境中,观察者感兴趣的是由传感器网络监测得到的与时间-空间相关的事件,而不是传感器本身或者大量无关的观察数据.观察者会经常提出与事件相关的时-空查询,例如:“网络覆盖的某地理区域R中10:00~11:00发生了哪些事件?”.由于每个传感器节点只有有限的能量,因此,研究能量有效性的时-空查询处理算法成为一个重要的研究课题.给出了一种以数据为中心的时-空查询处理算法.针对3种不同的存储策略:以数据为中心的存储、外部存储和节点本地存储,分析比较了节点的能量消耗.系统地研究了在3种不同的数据存储策略下,事件发生的概率,节点密度,事件类型数目,查询数目,时-空查询地理区域的大小以及时-空查询时间窗口的大小对节点能量消耗的影响.理论与实验结果表明,在多数情况下,这种以数据为中心的时-空查询处理算法的能量消耗少于基于外部存储和本地存储的时-空查询处理算法.     

Collective Behavior of G-Type Automata

The adaptive capabilities of automata are judged primarily on the basis of their behavior in random environments (situations). One can, of course, study these properties from various points of view, but the ability of automata to participate in games, i.e., their purposive collective behavior, is of special interest. This means that we have a ν-person game, the players being given not only the rules of the game, but also any other information that may be useful, such as the strategies of all the participants. It is assumed that if this game admits a behavior which is most advantageous for all the players (“the game has a solution”), then the competent and reasonable participants will adopt this behavior.     

Detangler: Visual Analytics for Multiplex Networks

A multiplex network has links of different types, allowing it to express many overlapping types of relationships. A core task in network analysis is to evaluate and understand group cohesion; that is, to explain why groups of elements belong together based on the underlying structure of the network. We present Detangler, a system that supports visual analysis of group cohesion in multiplex networks through dual linked views. These views feature new data abstractions derived from the original multiplex network: the substrate network and the catalyst network. We contribute two novel techniques that allow the user to analyze the complex structure of the multiplex network without the extreme visual clutter that would result from simply showing it directly. The harmonized layout visual encoding technique provides spatial stability between the substrate and catalyst views. The pivot brushing interaction technique supports linked highlighting between the views based on computations in the underlying multiplex network to leapfrog between subsets of catalysts and substrates. We present results from the motivating application domain of annotated news documents with a usage scenario and preliminary expert feedback. A second usage scenario presents group cohesion analysis of the social network of the early American independence movement.     

DimSUM: Dimension and Scale Unifying Map for Visual Abstraction of DNA Origami Structures

We present a novel visualization concept for DNA origami structures that integrates a multitude of representations into a Dimension and Scale Unifying Map (DimSUM). This novel abstraction map provides means to analyze, smoothly transition between, and interact with many visual representations of the DNA origami structures in an effective way that was not possible before. DNA origami structures are nanoscale objects, which are challenging to model in silico. In our holistic approach we seamlessly combine three‐dimensional realistic shape models, two‐dimensional diagrammatic representations, and ordered alignments in one‐dimensional arrangements, with semantic transitions across many scales. To navigate through this large, two‐dimensional abstraction map we highlight locations that users frequently visit for certain tasks and datasets. Particularly interesting viewpoints can be explicitly saved to optimize the workflow. We have developed DimSUM together with domain scientists specialized in DNA nanotechnology. In the paper we discuss our design decisions for both the visualization and the interaction techniques. We demonstrate two practical use cases in which our approach increases the specialists’ understanding and improves their effectiveness in the analysis. Finally, we discuss the implications of our concept for the use of controlled abstraction in visualization in general.     

基于ATM的群通信问题的研究*

群通信在并行计算中起着重要的作用.ATM(asynchronous transfer mode)网络有许多特点使之适合群通信.如何有效地利用ATM的这些特点来实现群通信操作是一个重要的研究课题.该文提出了一种基于ATM的群通信结构——混合树(Hybrid-Tree),该结构适合动态组中的群通信,并且能有效地利用ATM的特点.文中提出的组管理协议和树结构维护方法很好地解决了树结构的维护问题.     

网络集群行为初探

本文通过分析网络集群行为的特征、原因以及与其相关的法律规定,以求对其有初步认识,并对构建网络集群行为的社会控制机制提出自己的看法。     

Game-Theoretic Models of Binary Collective Behavior

Automation and Remote Control - We study game-theoretic models by solving algebraic equations that characterize the Nash equilibrium rather than from the viewpoint of maxima of the players’...     

NEVA: Visual Analytics to Identify Fraudulent Networks

Trust-ability, reputation, security and quality are the main concerns for public and private financial institutions. To detect fraudulent behaviour, several techniques are applied pursuing different goals. For well-defined problems, analytical methods are applicable to examine the history of customer transactions. However, fraudulent behaviour is constantly changing, which results in ill-defined problems. Furthermore, analysing the behaviour of individual customers is not sufficient to detect more complex structures such as networks of fraudulent actors. We propose NEVA (Network dEtection with Visual Analytics), a Visual Analytics exploration environment to support the analysis of customer networks in order to reduce false-negative and false-positive alarms of frauds. Multiple coordinated views allow for exploring complex relations and dependencies of the data. A guidance-enriched component for network pattern generation, detection and filtering support exploring and analysing the relationships of nodes on different levels of complexity. In six expert interviews, we illustrate the applicability and usability of NEVA.     

A Characterization of Interactive Visual Data Stories With a Spatio-Temporal Context

Large-scale issues with a spatial and temporal context such as the COVID-19 pandemic, the war against Ukraine, and climate change have given visual storytelling with data a lot of attention in online journalism, confirming its high effectiveness and relevance for conveying stories. Thus, new ways have emerged that expand the space of visual storytelling techniques. However, interactive visual data stories with a spatio-temporal context have not been extensively studied yet. Particularly quantitative information about the used layout and media, the visual storytelling techniques, and the visual encoding of space-time is relevant to get a deeper understanding of how such stories are commonly built to convey complex information in a comprehensible way. Covering these three aspects, we propose a design space derived by merging and adjusting existing approaches, which we used to categorize 130 collected web-based visual data stories with a spatio-temporal context from between 2018 and 2022. An analyzis of the collected data reveals the power of large-scale issues to shape the landscape of storytelling techniques and a trend towards a simplified consumability of stories. Taken together, our findings can serve story authors as inspiration regarding which storytelling techniques to include in their own spatio-temporal data stories.     

面向视觉变量感知特征的时空过程可视化模型

时空过程可视化具有重要的研究价值与意义。以时空过程为目标,在分析时空数据分类与时空过程的基础上,综合考虑时空视觉变量、感知特征、可视化分类与表现形式等要素,提出时空过程可视化模型S-TProc_VisModel。该模型包含模型输入、视觉变量、视觉感知特征、时空过程可视化形式、模型输出五个部分,可以划分为时空数据、时空过程、视觉变量、视觉感知、可视化类型、表现形式、可视化成果七个层次。利用该模型不仅能有效表达时空要素的位置、形态,还能描述事件中的时空过程及时态变化。经实验证明,S-TProc_VisModel模型能够充分展示时空过程内容,并能形象完整地展示过程细节。     

交通事故局部时空模式的张量分解可视分析方法

交通事故数据中蕴含细粒度的局部时空模式,但它们往往被数据全集所掩盖而难以被发现.找到合适的数据子集是发现有意义的局部时空模式的重要前提,也是最为烦琐的过程.为此,提出基于张量分解方法自动获取数据子集的交通事故局部时空模式可视分析方法.首先,对交通事故数据集进行张量建模;并运用张量分解方法自动获取一组捕获了数据集各维度上...     

Collective Mining of Bayesian Networks from Distributed Heterogeneous Data

We present a collective approach to learning a Bayesian network from distributed heterogeneous data. In this approach, we first learn a local Bayesian network at each site using the local data. Then each site identifies the observations that are most likely to be evidence of coupling between local and non-local variables and transmits a subset of these observations to a central site. Another Bayesian network is learnt at the central site using the data transmitted from the local site. The local and central Bayesian networks are combined to obtain a collective Bayesian network, which models the entire data. Experimental results and theoretical justification that demonstrate the feasibility of our approach are presented.16 November 2001     

Emergence of Collective Behavior in Evolving Populations of Flying Agents

We demonstrate the emergence of collective behavior in two evolutionary computation systems, one an evolutionary extension of a classic (highly constrained) flocking algorithm and the other a relatively un-constrained system in which the behavior of agents is governed by evolved computer programs. The first system demonstrates the evolution of a form of multicellular organization, while the second demonstrates the evolution of a form of altruistic food sharing. In this article we describe both systems in detail, document the emergence of collective behavior, and argue that these systems present new opportunities for the study of group dynamics in an evolutionary context. We also provide a brief overview of the breve simulation environment in which the systems were produced, and of breve’s facilities for the rapid, exploratory development of visualization strategies for artificial life.     

基于统计模型的社会网络群体关注度的分析与预测

社会网络中的群体关注度问题是研究网络社区中的信息或事件如何引起广大网络用户的关注、并随着信息的传播逐渐变化的问题.分析了网络社区用户对网络中的信息对象的关注特点,并通过统计复旦大学日月光华BBS论坛用户的发帖、回帖数据来验证关于用户群体关注度的分析结论.同时,基于大量数据的统计分析构造出一个群体关注度预测模型,用以预测论坛用户对于新出现的信息或事件的群体关注度演化趋势.这种预测模型的生成和预测方法也适用于其他社会网络平台上的群体关注度分析和预测,因而在网络广告投放、网络舆论监测和控制等方面都具有重要的应用价值.     

视觉传感网络分布式在线数据关联

数据关联是视觉传感网络监控系统的基本问题之一. 本文针对无重叠视域视觉监控网络的多目标跟踪问题提出一种 基于多外观模型的视觉传感网络在线分布式数据关联方法,将同一目标在不同摄像机节点上的外观用不同的高斯模型描述,由分布式推理算法综合利用外观与时空观测计算关联变量的后验概率,同时通过近似最大似然估计算法对各传感节点上的外观模型参数进行在线估计. 实验结果表明了所提方法的有效性.     

Malware-Propagative Mobile Ad Hoc Networks: Asymptotic Behavior Analysis

In this paper, the spreading of malicious software over ad hoc networks, where legitimate nodes are prone to propagate the infections they receive from either an attacker or their already infected neighbors, is analyzed. Considering the Susceptible-Infected-Susceptible （SIS） node infection paradigm we propose a probabilistic model, on the basis of the theory of closed queuing networks, that aims at describing the aggregated behavior of the system when attacked by malicious nodes. Because of its nature, the model is also able to deal more effectively with the stochastic behavior of attackers and the inherent probabilistic nature of the wireless environment. The proposed model is able to describe accurately the asymptotic behavior of malware-propagative large scale ad hoc networking environments. Using the Norton equivalent of the closed queuing network, we obtain analytical results for its steady state behavior, which in turn is used for identifying the critical parameters affecting the operation of the network. Finally, through modeling and simulation, some additional numerical results are obtained with respect to the behavior of the system when multiple attackers are present, and regarding the time-dependent evolution and impact of an attack.     

高效节能的视觉传感器网络目标覆盖算法

针对视觉传感器网络目标覆盖过程中因覆盖冗余、节点剩余能量不均等原因导致网络寿命过短的问题,设计一种视觉传感器网络目标覆盖算法。该算法基于节点与目标的覆盖关联关系,利用关系矩阵及相关运算对覆盖频繁目标集进行挖掘,进而对工作节点进行动态选举,以此延长网络的生存时间。实验结果表明,该算法在保证网络覆盖质量的前提下能够高效地调度工作节点,均衡节点耗能,有效延长网络寿命。