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Continuous aggregate nearest neighbor queries / H. Elmongui in Geoinformatica, vol 17 n° 1 (January 2013)  

Public [article]  inGeoinformatica > vol 17 n° 1 (January 2013) . - pp 63 - 95 Titre : Continuous aggregate nearest neighbor queries Type de document : Article/Communication Auteurs : H. Elmongui, Auteur ; M. Mokbel, Auteur ; W. Aref, Auteur Année de publication : 2013 Article en page(s) : pp 63 - 95 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Systèmes d'information géographique [Termes IGN] agrégation spatiale [Termes IGN] données spatiotemporelles [Termes IGN] flux de données [Termes IGN] objet mobile [Termes IGN] plus proche voisin, algorithme du [Termes IGN] requête continue [Termes IGN] requête spatiotemporelle Résumé : (Auteur) This paper addresses the problem of continuous aggregate nearest-neighbor (CANN) queries for moving objects in spatio-temporal data stream management systems. A CANN query specifies a set of landmarks, an integer k, and an aggregate distance function f (e.g., min, max, or sum), where f computes the aggregate distance between a moving object and each of the landmarks. The answer to this continuous query is the set of k moving objects that have the smallest aggregate distance f. A CANN query may also be viewed as a combined set of nearest neighbor queries. We introduce several algorithms to continuously and incrementally answer CANN queries. Extensive experimentation shows that the proposed operators outperform the state-of-the-art algorithms by up to a factor of 3 and incur low memory overhead. Numéro de notice : A2013-047 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE/INFORMATIQUE Nature : Article DOI : 10.1007/s10707-011-0149-0 En ligne : https://doi.org/10.1007/s10707-011-0149-0 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=32185 [article]

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Query-aware location anonymization for road networks / C. Chow in Geoinformatica, vol 15 n° 3 (July 2011)  

Public [article]  inGeoinformatica > vol 15 n° 3 (July 2011) . - pp 571 - 607 Titre : Query-aware location anonymization for road networks Type de document : Article/Communication Auteurs : C. Chow, Auteur ; M. Mokbel, Auteur ; Jie Bao, Auteur ; X. Liu, Auteur Année de publication : 2011 Article en page(s) : pp 571 - 607 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Analyse spatiale [Termes IGN] espace euclidien [Termes IGN] requête spatiale [Termes IGN] réseau routier [Termes IGN] service fondé sur la position Résumé : (Auteur) Recently, several techniques have been proposed to protect the user location privacy for location-based services in the Euclidean space. Applying these techniques directly to the road network environment would lead to privacy leakage and inefficient query processing. In this paper, we propose a new location anonymization algorithm that is designed specifically for the road network environment. Our algorithm relies on the commonly used concept of spatial cloaking, where a user location is cloaked into a set of connected road segments of a minimum total length L including at least K users. Our algorithm is “query-aware” as it takes into account the query execution cost at a database server and the query quality, i.e., the number of objects returned to users by the database server, during the location anonymization process. In particular, we develop a new cost function that balances between the query execution cost and the query quality. Then, we introduce two versions of our algorithm, namely, pure greedy and randomized greedy, that aim to minimize the developed cost function and satisfy the user specified privacy requirements. To accommodate intervals with a high workload, we introduce a shared execution paradigm that boosts the scalability of our location anonymization algorithm and the database server to support large numbers of queries received in a short time period. Extensive experimental results show that our algorithms are more efficient and scalable than the state-of-the-art technique, in terms of both query execution cost and query quality. The results also show that our algorithms have very strong resilience to two privacy attacks, namely, the replay attack and the center-of-cloaked-area attack. Numéro de notice : A2011-212 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE Nature : Article DOI : 10.1007/s10707-010-0117-0 Date de publication en ligne : 06/11/2010 En ligne : https://doi.org/10.1007/s10707-010-0117-0 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=30990 [article]

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