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[show abstract]
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ABSTRACT: With the advent of reliable positioning technologies and prevalence of
location-based services, it is now feasible to accurately study the propagation
of items such as infectious viruses, sensitive information pieces, and malwares
through a population of moving objects, e.g., individuals, mobile devices, and
vehicles. In such application scenarios, an item passes between two objects
when the objects are sufficiently close (i.e., when they are, so-called, in
contact), and hence once an item is initiated, it can penetrate the object
population through the evolving network of contacts among objects, termed
contact network. In this paper, for the first time we define and study
reachability queries in large (i.e., disk-resident) contact datasets which
record the movement of a (potentially large) set of objects moving in a spatial
environment over an extended time period. A reachability query verifies whether
two objects are "reachable" through the evolving contact network represented by
such contact datasets. We propose two contact-dataset indexes that enable
efficient evaluation of such queries despite the potentially humongous size of
the contact datasets. With the first index, termed ReachGrid, at the query time
only a small necessary portion of the contact network which is required for
reachability evaluation is constructed and traversed. With the second approach,
termed ReachGraph, we precompute reachability at different scales and leverage
these precalculations at the query time for efficient query processing. We
optimize the placement of both indexes on disk to enable efficient index
traversal during query processing. We study the pros and cons of our proposed
approaches by performing extensive experiments with both real and synthetic
data. Based on our experimental results, our proposed approaches outperform
existing reachability query processing techniques in contact n...[truncated].
05/2012;
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Web and Wireless Geographical Information Systems - 10th International Symposium, W2GIS 2011, Kyoto, Japan, March 3-4, 2011. Proceedings; 01/2011
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Advances in Spatial and Temporal Databases - 12th International Symposium, SSTD 2011, Minneapolis, MN, USA, August 24-26, 2011, Proceedings; 01/2011
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Proceedings of the 2011 ACM SIGSPATIAL International Workshop on GeoStreaming, IWGS 2011, November 1, 2011, Chicago, IL, USA; 01/2011
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ABSTRACT: In this paper, we present TransDec, an end-to-end-data-driven system which enables spatiotemporal queries in transportation systems with dynamic, real-time and historical data. TransDec fuses a variety of real-world spatiotemporal datasets including massive traffic sensor data, trajectory data, transportation network data, and point-of-interest data to create an immersive and realistic virtual model of a transportation system. With TransDec, we address the challenges in visualization, monitoring, querying and analysis of dynamic and large-scale transportation data in both time and space.
Data Engineering, International Conference on. 02/2010;
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IEEE MultiMedia. 01/2010; 17:14-23.
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Database Systems for Advanced Applications, 15th International Conference, DASFAA 2010, Tsukuba, Japan, April 1-4, 2010, Proceedings, Part I; 01/2010
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Proceedings of the 26th International Conference on Data Engineering, ICDE 2010, March 1-6, 2010, Long Beach, California, USA; 01/2010
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Cloud Computing, Second International Conference, CloudCom 2010, November 30 - December 3, 2010, Indianapolis, Indiana, USA, Proceedings; 01/2010
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Database and Expert Systems Applications, 21st International Conference, DEXA 2010, Bilbao, Spain, August 30 - September 3, 2010, Proceedings, Part I; 01/2010
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Proceedings of the 2010 ACM SIGSPATIAL International Workshop on GeoStreaming, IWGS 2010, November 2, 2010, San Jose, CA, USA; 01/2010
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18th ACM SIGSPATIAL International Symposium on Advances in Geographic Information Systems, ACM-GIS 2010, November 3-5, 2010, San Jose, CA, USA, Proceedings; 01/2010
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Proceedings of the 2010 International Workshop on Location Based Social Networks, LBSN 2010, November 2, 2010, San Jose, CA, USA, Proceedings; 01/2010
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Databases in Networked Information Systems, 6th International Workshop, DNIS 2010, Aizu-Wakamatsu, Japan, March 29-31, 2010. Proceedings; 01/2010
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[show abstract]
[hide abstract]
ABSTRACT: In this paper we propose Scoop, a mechanism to implement the “partial read operation” for peer-to-peer databases. A peer-to-peer database is a database
that its relations are horizontally fragmented and distributed among the nodes of a peer-to-peer network. The partial read
operation is a data retrieval operation required for approximate query processing in peer-to-peer databases. A partial read
operation answers to β -queries: given β ∈ [0,1]and a relation R, a fraction β of the tuples in R must be retrieved from the database to answer a β -query. Despite the simplicity of the β -query, due to the distributed, evolving and autonomous nature of the peer-to-peer databases correct and efficient implementation
of the partial read operation is challenging. Scoop is designed based on an epidemic dissemination algorithm. We model the
epidemic dissemination as a percolation problem and by rigorous percolation analysis tune Scoop per-query and on-the-fly to
answer β -queries correctly and efficiently. We prove the correctness of Scoop by theoretical analysis, and verify the efficiency
of Scoop in terms of query cost and query time via extensive simulation.
12/2009: pages 601-627;
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GeoSensor Networks, Third International Conference, GSN 2009, Oxford, UK, July 13-14, 2009. Proceedings; 01/2009
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Advances in Spatial and Temporal Databases, 11th International Symposium, SSTD 2009, Aalborg, Denmark, July 8-10, 2009, Proceedings; 01/2009
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17th ACM SIGSPATIAL International Symposium on Advances in Geographic Information Systems, ACM-GIS 2009, November 4-6, 2009, Seattle, Washington, USA, Proceedings; 01/2009
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Proceedings of the Second International Workshop on Computational Transportation Science, IWCTS 2009, November 3, 2009, Seattle, Washington, USA, Proceedings; 01/2009
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Computer Communications. 01/2008; 31:332-345.
