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Riso-Tree: An Efficient and Scalable Index for Spatial Entities in Graph Database Management Systems Riso-Tree:图形数据库管理系统中空间实体的高效可扩展索引
Pub Date : 2021-06-16 DOI: 10.1145/3450945
Yuhan Sun, Mohamed Sarwat
With the ubiquity of spatial data, vertexes or edges in graphs can possess spatial location attributes side by side with other non-spatial attributes. For instance, as of June 2018, the Wikidata kn...
由于空间数据的普遍性,图中的点或边可以与其他非空间属性同时具有空间位置属性。例如,截至2018年6月,维基数据知道……
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引用次数: 2
Spatial Interpolation Techniques on Participatory Sensing Data 参与式传感数据的空间插值技术
Pub Date : 2021-06-07 DOI: 10.1145/3457609
Asif Iqbal Middya, Sarbani Roy
Spatial distributions of data of natural phenomena can be estimated by using different spatial interpolation techniques. These techniques can be used for the purpose of developing urban noise pollu...
利用不同的空间插值技术可以估计自然现象数据的空间分布。这些技术可用于治理城市噪声污染。
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引用次数: 9
Predicting Spatio-Temporal Phenomena of Mobile Resources in Sensor Cloud Infrastructure 传感器云基础设施中移动资源时空现象预测
Pub Date : 2021-06-07 DOI: 10.1145/3446936
Sunanda Bose, Sujay Paul, N. Mukherjee
Integration of sensor and cloud technologies enable distributed sensing and data collection. We consider a scenario when sensing requests are originated from sensor aware applications that are hosted inside sensor-cloud infrastructures. These requests need to be satisfied using geographically distributed sensors. However, if the sensing resources are mobile, then sensing territory is not limited to a fixed region, rather spatially diverse. In this work, we present a generic scheme for integrating spatio-temporal information of mobile sensors for Internet of Things– (IoT) based environment monitoring system. A set of algorithms are proposed in this work to model spatial and temporal features of mobile resources and exploit resource mobility. We also propose probabilistic models to measure feasibility of a resource to sense a specific spatio-temporal phenomenon. We rank the resources based on their feasibility of satisfying the sensing requests and later use the information for efficient resource allocation and scheduling.
传感器和云技术的集成使分布式传感和数据收集成为可能。我们考虑这样一种场景,即感知请求来自托管在传感器云基础设施中的传感器感知应用程序。这些请求需要使用地理上分布的传感器来满足。然而,如果传感资源是移动的,那么传感领域就不局限于一个固定的区域,而是具有空间多样性。在这项工作中,我们提出了一种基于物联网(IoT)环境监测系统的移动传感器时空信息集成的通用方案。本文提出了一套模拟移动资源时空特征和开发资源流动性的算法。我们还提出了概率模型来衡量资源感知特定时空现象的可行性。我们根据满足感知请求的可行性对资源进行排序,然后利用这些信息进行有效的资源分配和调度。
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引用次数: 1
Efficient Processing of Relevant Nearest-Neighbor Queries 相关最近邻查询的高效处理
Pub Date : 2016-10-14 DOI: 10.1145/2934675
Christodoulos Efstathiades, Alexandros Efentakis, D. Pfoser
Novel Web technologies and resulting applications have led to a participatory data ecosystem that, when utilized properly, will lead to more rewarding services. In this work, we investigate the case of Location-Based Services, specifically how to improve the typical location-based Point-of-Interest (POI) request processed as a k-Nearest-Neighbor query. This work introduces Links-of-Interest (LOI) between POIs as a means to increase the relevance and overall result quality of such queries. By analyzing user-contributed content in the form of travel blogs, we establish the overall popularity of an LOI, that is, how frequently the respective POI pair was visited and is mentioned in the same context. Our contribution is a query-processing method for so-called k-Relevant Nearest Neighbor (k-RNN) queries that considers spatial proximity in combination with LOI information to retrieve close-by and relevant (as judged by the crowd) POIs. Our method is based on intelligently combining indices for spatial data (a spatial grid) and for relevance data (a graph) during query processing. Using landmarks as a means to prune the search space in the Relevance Graph, we improve the proposed methods. Using in addition A*-directed search, the query performance can be further improved. An experimental evaluation using real and synthetic data establishes that our approach efficiently solves the k-RNN problem.
新颖的Web技术和由此产生的应用程序已经形成了一个参与式的数据生态系统,如果使用得当,将会带来更多有益的服务。在这项工作中,我们研究了基于位置的服务的情况,特别是如何改进作为k近邻查询处理的典型基于位置的兴趣点(POI)请求。这项工作引入了poi之间的兴趣链接(LOI),作为提高此类查询的相关性和整体结果质量的一种手段。通过分析用户以旅游博客的形式贡献的内容,我们建立了LOI的总体流行度,即各自的POI对被访问和在同一上下文中被提及的频率。我们的贡献是一种用于所谓的k相关最近邻(k-RNN)查询的查询处理方法,该方法将空间接近性与LOI信息结合起来考虑,以检索相近的和相关的(由人群判断的)poi。我们的方法是基于在查询处理过程中对空间数据(空间网格)和相关数据(图)的索引进行智能组合。我们使用地标作为在关联图中修剪搜索空间的手段,改进了所提出的方法。使用另外的A*定向搜索,可以进一步提高查询性能。使用真实和合成数据的实验评估表明,我们的方法有效地解决了k-RNN问题。
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引用次数: 5
Mining At Most Top-K% Spatiotemporal Co-occurrence Patterns in Datasets with Extended Spatial Representations 扩展空间表示数据集中Top-K%时空共现模式的挖掘
Pub Date : 2016-10-14 DOI: 10.1145/2936775
K. Pillai, R. Angryk, J. Banda, Dustin J. Kempton, Berkay Aydin, P. Martens
Spatiotemporal co-occurrence patterns (STCOPs) in datasets with extended spatial representations are two or more different event types, represented as polygons evolving in time, whose instances often occur together in both space and time. Finding STCOPs is an important problem in domains such as weather monitoring, wildlife migration, and solar physics. Nevertheless, in real life, it is difficult to find a suitable prevalence threshold without prior domain-specific knowledge. In this article, we focus our work on the problem of mining at most top-K% of STCOPs from continuously evolving spatiotemporal events that have polygon-like representations, without using a user-specified prevalence threshold.
具有扩展空间表示的数据集中的时空共现模式(stcop)是两种或两种以上不同的事件类型,以随时间演变的多边形表示,其实例通常在空间和时间上同时发生。寻找stcop是天气监测、野生动物迁徙和太阳物理等领域的重要问题。然而,在现实生活中,如果没有事先的特定领域知识,很难找到合适的流行阈值。在本文中,我们的工作重点是在不使用用户指定的流行阈值的情况下,从具有多边形表示的连续发展的时空事件中挖掘最多top-K%的stcop问题。
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引用次数: 8
Simulating Our LifeSteps by Example 用例子模拟我们的生活步骤
Pub Date : 2016-10-14 DOI: 10.1145/2937753
N. Pelekis, Stylianos Sideridis, Panagiotis Tampakis, Y. Theodoridis
During the past few decades, a number of effective methods for indexing, query processing, and knowledge discovery in moving object databases have been proposed. An interesting research direction that has recently emerged handles semantics of movement instead of raw spatio-temporal data. Semantic annotations, such as “stop,” “move,” “at home,” “shopping,” “driving,” and so on, are either declared by the users (e.g., through social network apps) or automatically inferred by some annotation method and are typically presented as textual counterparts along with spatial and temporal information of raw trajectories. It is natural to argue that such “spatio-temporal-textual” sequences, called semantic trajectories, form a realistic representation model of the complex everyday life (hence, mobility) of individuals. Towards handling semantic trajectories of moving objects in Semantic Mobility Databases, the lack of real datasets leads to the need to design realistic simulators. In the context of the above discussion, the goal of this work is to realistically simulate the mobility life of a large-scale population of moving objects in an urban environment. Two simulator variations are presented: the core Hermoupolis simulator is parametric driven (i.e., user-defined parameters tune every movement aspect), whereas the expansion of the former, called Hermoupolisby-example, follows the generate-by-example paradigm and is self-tuned by looking inside a real small (sample) dataset. We stress test our proposal and demonstrate its novel characteristics with respect to related work.
在过去的几十年里,人们提出了许多有效的移动对象数据库的索引、查询处理和知识发现方法。最近出现的一个有趣的研究方向是处理运动的语义而不是原始的时空数据。语义注释,如“停止”、“移动”、“在家”、“购物”、“开车”等,要么由用户声明(例如通过社交网络应用程序),要么由某些注释方法自动推断,通常与原始轨迹的空间和时间信息一起以文本形式呈现。人们很自然地认为,这种被称为语义轨迹的“时空文本”序列,形成了个人复杂的日常生活(因此,流动性)的现实表现模型。为了在语义移动数据库中处理运动对象的语义轨迹,缺乏真实的数据集导致需要设计逼真的模拟器。在上述讨论的背景下,本工作的目标是真实地模拟城市环境中大规模移动物体人口的移动生活。提出了两种模拟器变体:核心Hermoupolis模拟器是参数驱动的(即,用户定义的参数调整每个运动方面),而前者的扩展称为Hermoupolisby-example,遵循逐例生成范例,并通过查看真实的小(样本)数据集进行自调优。我们对我们的建议进行了压力测试,并在相关工作中展示了其新颖性。
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引用次数: 9
TRIFL: A Generic Trajectory Index for Flash Storage TRIFL:闪存存储的通用轨迹索引
Pub Date : 2015-11-05 DOI: 10.1145/2786758
Dai Hai Ton That, I. S. Popa, K. Zeitouni
Due to several important features, such as high performance, low power consumption, and shock resistance, NAND flash has become a very popular stable storage medium for embedded mobile devices, personal computers, and even enterprise servers. However, the peculiar characteristics of flash memory require redesigning the existing data storage and indexing techniques that were devised for magnetic hard disks. In this article, we propose TRIFL, an efficient and generic TRajectory Index for FLash. TRIFL is designed around the key requirements of trajectory indexing and flash storage. TRIFL is generic in the sense that it is efficient for both simple flash storage devices such as SD cards and more powerful devices such as solid state drives. In addition, TRIFL is supplied with an online self-tuning algorithm that allows adapting the index structure to the workload and the technical specifications of the flash storage device to maximize the index performance. Moreover, TRIFL achieves good performance with relatively low memory requirements, which makes the index appropriate for many application scenarios. The experimental evaluation shows that TRIFL outperforms the representative indexing methods on magnetic disks and flash disks.
由于具有高性能、低功耗和抗冲击等重要特性,NAND闪存已成为嵌入式移动设备、个人计算机甚至企业服务器非常流行的稳定存储介质。但是,快闪存储器的特殊特性要求重新设计为磁性硬盘设计的现有数据存储和索引技术。在本文中,我们提出了一种高效通用的FLash轨迹索引TRIFL。TRIFL是围绕轨迹索引和闪存存储的关键要求设计的。从某种意义上说,TRIFL是通用的,它对简单的闪存设备(如SD卡)和更强大的设备(如固态驱动器)都是有效的。此外,TRIFL还提供了一个在线自调优算法,该算法允许根据工作负载和闪存存储设备的技术规格调整索引结构,以最大限度地提高索引性能。此外,TRIFL在相对较低的内存需求下实现了良好的性能,这使得该索引适用于许多应用场景。实验结果表明,该方法优于传统的磁盘和闪存索引方法。
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引用次数: 9
Symbolic Trajectories 象征性的轨迹
Pub Date : 2015-11-05 DOI: 10.1145/2786756
R. H. Güting, Fabio Valdés, M. Damiani
Due to the proliferation of GPS-enabled devices in vehicles or with people, large amounts of position data are recorded every day and the management of such mobility data, also called trajectories, is a very active research field. A lot of effort has gone into discovering “semantics” from the raw geometric trajectories by relating them to the spatial environment or finding patterns, for example, by data mining techniques. A question is how the resulting “meaningful” trajectories can be represented or further queried. In this article, we propose a systematic study of annotated trajectory databases. We define a very simple generic model called symbolic trajectory to capture a wide range of meanings derived from a geometric trajectory. Essentially, a symbolic trajectory is just a time-dependent label; variants have sets of labels, places, or sets of places. They are modeled as abstract data types and integrated into a well-established framework of data types and operations for moving objects. Symbolic trajectories can represent, for example, the names of roads traversed obtained by map matching, transportation modes, speed profile, cells of a cellular network, behaviors of animals, cinemas within 2km distance, and so forth. Symbolic trajectories can be combined with geometric trajectories to obtain annotated trajectories. Besides the model, the main technical contribution of the article is a language for pattern matching and rewriting of symbolic trajectories. A symbolic trajectory can be represented as a sequence of pairs (called units) consisting of a time interval and a label. A pattern consists of unit patterns (specifications for time interval and/or label) and wildcards, matching units and sequences of units, respectively, and regular expressions over such elements. It may further contain variables that can be used in conditions and in rewriting. Conditions and expressions in rewriting may use arbitrary operations available for querying in the host DBMS environment, which makes the language extensible and quite powerful. We formally define the data model and syntax and semantics of the pattern language. Query operations are offered to integrate pattern matching, rewriting, and classification of symbolic trajectories into a DBMS querying environment. Implementation of the model using finite state machines is described in detail. An experimental evaluation demonstrates the efficiency of the implementation. In particular, it shows dramatic improvements in storage space and response time in a comparison of symbolic and geometric trajectories for some simple queries that can be executed on both symbolic and raw trajectories.
由于车辆或人员中的gps设备的激增,每天都会记录大量的位置数据,并且这些移动数据(也称为轨迹)的管理是一个非常活跃的研究领域。通过将原始几何轨迹与空间环境联系起来,或者通过数据挖掘技术寻找模式,已经在从原始几何轨迹中发现“语义”方面付出了很多努力。问题是如何表示或进一步查询得到的“有意义的”轨迹。在本文中,我们提出了一个系统的研究带注释的轨迹数据库。我们定义了一个非常简单的通用模型,称为符号轨迹,以捕获从几何轨迹派生的广泛意义。本质上,符号轨迹只是一个与时间相关的标签;变体具有一组标签、位置或一组位置。它们被建模为抽象数据类型,并集成到一个完善的数据类型和移动对象操作框架中。符号轨迹可以表示,例如,通过地图匹配获得的经过的道路名称、交通方式、速度剖面、蜂窝网络的单元、动物的行为、2公里内的电影院等等。符号轨迹可以与几何轨迹相结合,得到标注轨迹。除了模型之外,本文的主要技术贡献是一种用于模式匹配和符号轨迹重写的语言。符号轨迹可以表示为由时间间隔和标签组成的一对序列(称为单元)。模式由单元模式(时间间隔和/或标签的规范)和通配符、匹配单元和单元序列以及这些元素上的正则表达式组成。它可以进一步包含可用于条件和重写的变量。重写中的条件和表达式可以使用宿主DBMS环境中查询可用的任意操作,这使得该语言具有可扩展性和相当强大的功能。我们正式定义了数据模型以及模式语言的语法和语义。查询操作提供了将符号轨迹的模式匹配、重写和分类集成到DBMS查询环境中的功能。详细描述了利用有限状态机实现该模型。实验验证了该方法的有效性。特别是,对于一些可以在符号轨迹和原始轨迹上执行的简单查询,通过比较符号轨迹和几何轨迹,它显示了在存储空间和响应时间方面的显著改进。
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引用次数: 56
Efficient Geo-Fencing via Hybrid Hashing: A Combination of Bucket Selection and In-Bucket Binary Search 基于混合哈希的高效地理围栏:桶选择和桶内二进制搜索的组合
Pub Date : 2015-11-05 DOI: 10.1145/2774219
Suhua Tang, Yi Yu, Roger Zimmermann, S. Obana
Geo-fencing, as a spatial join between points (moving objects) and polygons (spatial range), is widely used in emerging location-based services to trigger context-aware events. It faces the challenge of real-time processing a large number of time-variant complex polygons, when points are constantly moving. Following the filter-and-refine policy, in our previous work, we proposed to organize edges per polygon in hash tables to improve the performance of the refining stage. The number of edges, however, is uneven among buckets. As a result, some points that happen to match big buckets with many edges will have much longer responses than usual. In this article, we solve this problem from two aspects: (i) Constructing multiple parallel hash tables and dynamically selecting the bucket with fewest edges and (ii) sorting edges in a bucket so as to realize the crossing number algorithm by binary search. We further combine the two to suggest a hybrid hashing scheme that takes a better tradeoff between real-time pairing points with polygons and system overhead of building hash tables. Extensive analyses and evaluations on two real-world datasets confirm that the proposed scheme can effectively reduce the pairing time in terms of both the average and distribution.
地理围栏作为点(移动物体)和多边形(空间范围)之间的空间连接,被广泛应用于新兴的基于位置的服务中,以触发上下文感知事件。它面临着实时处理大量时变复杂多边形的挑战,当点不断移动时。在我们之前的工作中,遵循过滤和精炼策略,我们提出在哈希表中组织每个多边形的边,以提高精炼阶段的性能。然而,桶的边缘数量是不均匀的。因此,一些点恰好匹配有许多边的大桶,会有比平常更长时间的响应。本文从两个方面解决这一问题:(1)构造多个并行哈希表,动态选择边数最少的桶;(2)对桶内的边进行排序,通过二叉搜索实现交叉数算法。我们进一步将两者结合起来,提出一种混合哈希方案,该方案在多边形的实时配对点和构建哈希表的系统开销之间进行了更好的权衡。通过对两个实际数据集的分析和评价,证实了该方案在平均和分布两方面都能有效地缩短配对时间。
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引用次数: 4
Tilewise Accumulated Cost Surface Computation with Graphics Processing Units 图形处理单元的平铺累积成本曲面计算
Pub Date : 2015-11-05 DOI: 10.1145/2803172
J. Kovanen, T. Sarjakoski
Accumulated cost surfaces are used in a variety of fields that employ spatial analysis. Several algorithms have been suggested in the past for solving them efficiently or with minimal errors. Meanwhile, a new wave on the technological frontier has brought about general-purpose computing on GPUs. In this article, we describe how accumulated cost surfaces can be solved with CUDA. To verify the performance of our solution, we performed an experimental comparison against implementations run on a CPU. Our results with realistic cost models indicate that the move to GPUs can engender a speed-up of an order of magnitude.
累积成本面用于各种需要空间分析的领域。过去已经提出了几种算法来有效地或以最小的误差解决这些问题。与此同时,技术前沿的新浪潮带来了基于gpu的通用计算。在本文中,我们描述了如何使用CUDA解决累积成本曲面。为了验证我们的解决方案的性能,我们对在CPU上运行的实现进行了实验比较。我们使用现实成本模型的结果表明,转向gpu可以产生一个数量级的速度提升。
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引用次数: 5
期刊
ACM Trans. Spatial Algorithms Syst.
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