Cyrus Shahabi

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A frequent type of query in spatial networks (e.g., road networks) is to find the K nearest neighbors (KNN) of a given query object. With these networks, the distances between objects depend on their network connectivity and it is computationally expensive to compute the distances (e.g., shortest paths) between objects. In this paper, we propose a novel(More)
Mobile devices equipped with positioning capabilities (e.g., GPS) can ask location-dependent queries to Location Based Services (<i>LBS</i>). To protect privacy, the user location must not be disclosed. Existing solutions utilize a trusted anonymizer between the users and the LBS. This approach has several drawbacks: (<i>i</i>) All users must trust the(More)
In this paper, for the first time, we introduce the concept of Spatial Skyline Queries (SSQ). Given a set of data points <i>P</i> and a set of query points <i>Q</i> each data point has a number of derived spatial attributes each of which is the point's distance to a query point. An SSQ retrieves those points of <i>P</i> which are not dominated by any other(More)
With the ubiquity of mobile devices, <i>spatial crowdsourcing</i> is emerging as a new platform, enabling <i>spatial tasks</i> (i.e., tasks related to a location) assigned to and performed by human workers. In this paper, for the first time we introduce a taxonomy for spatial crowdsourcing. Subsequently, we focus on one class of this taxonomy, in which(More)
Sensed data in Wireless Sensor Networks (WSN) reflect the spatial and temporal correlations of physical attributes existing intrinsically in the environment. In this article, we present the Clustered AGgregation (CAG) algorithm that forms clusters of nodes sensing similar values within a given threshold (spatial correlation), and these clusters remain(More)
Real-world road-planning applications often result in the formulation of new variations of the nearest neighbor (NN) problem requiring new solutions. In this paper, we study an unexplored form of NN queries named optimal sequenced route (OSR) query in both vector and metric spaces. OSR strives to find a route of minimum length starting from a given source(More)
We propose to detect users navigationpaths to the advantage of web-site owners. First, we explain the design and implementationof a profiler which captures client’s selected links and pages order, accurate page viewing time and cache references, using a Java based remote agent. The information captured by the profiler is then utilized by a knowledge(More)
5 /42 • Any entity in the system can be adversarial – The LS and other clients – Slightly different for querying other users • Secure client/server communication channel – Any privacy violation should have included LS – We focus on LS as the most powerful adversary Privacy/Efficiency Dilemma •Privacy: Hiding knowledge of object & query locations from LS(More)
Scalable storage architectures allow for the addition of disks to increase storage capacity and/or bandwidth. In its general form, disk scaling also refers to disk removals when either capacity needs to be conserved or old disk drives are retired. Assuming random placement of blocks on multiple nodes of a continuous media server, our optimization objective(More)
We introduce a novel wavelet-based tree structure, termed TSA-tree, which improves the efficiency of multilevel trend and surprise queries on time sequence data. With the explosion of scientific observation data (some conceptualized as time-sequences), we are facing the challenge of efficiently storing, retrieving and analyzing this data. Frequent queries(More)