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Displaying 1-50 out of 79 total
Upgrading Uncompetitive Products Economically
Found in: Data Engineering, International Conference on
By Hua Lu,Christian S. Jensen
Issue Date:April 2012
pp. 977-988
The skyline of a multidimensional point set consists of the points that are not dominated by other points. In a scenario where product features are represented by multidimensional points, the skyline points may be viewed as representing competitive product...
 
Flexible and Efficient Resolution of Skyline Query Size Constraints
Found in: IEEE Transactions on Knowledge and Data Engineering
By Hua Lu, Christian S. Jensen, Zhenjie Zhang
Issue Date:July 2011
pp. 991-1005
Given a set of multidimensional points, a skyline query returns the interesting points that are not dominated by other points. It has been observed that the actual cardinality (s) of a skyline query result may differ substantially from the desired result c...
 
Outsourcing Search Services on Private Spatial Data
Found in: Data Engineering, International Conference on
By Man Lung Yiu, Gabriel Ghinita, Christian S. Jensen, Panos Kalnis
Issue Date:April 2009
pp. 1140-1143
Social networking and content sharing service providers, e.g., Facebook and Google Maps, enable their users to upload and share a variety of user-generated content, including location data such as points of interest. Users wish to share location data throu...
 
Expiration Times for Data Management
Found in: Data Engineering, International Conference on
By Albrecht Schmidt, Christian S. Jensen, Simonas Saltenis
Issue Date:April 2006
pp. 36
This paper describes an approach to incorporating the notion of expiration time into data management based on the relational model. Expiration times indicate when tuples cease to be current in a database. The paper presents a formal data model and a query ...
 
Research Challenges in Location-Enabled M-Services
Found in: Mobile Data Management, IEEE International Conference on
By Christian S. Jensen
Issue Date:January 2002
pp. 3
Rapid, sustained advances in key computing hardware technologies combine to enable a new class of computing services that aim to meet needs of mobile users. These ubiq-uitous and intelligent services adapt to each user's partic-ular preferences and current...
 
Extending Existing Dependency Theory to Temporal Databases
Found in: IEEE Transactions on Knowledge and Data Engineering
By Christian S. Jensen, Richard T. Snodgrass, Michael D. Soo
Issue Date:August 1996
pp. 563-582
<p><b>Abstract</b>—Normal forms play a central role in the design of relational databases. Several normal forms for temporal relational databases have been proposed. These definitions are particular to specific temporal data models, which...
 
Spatio-temporal joins on symbolic indoor tracking data
Found in: Data Engineering, International Conference on
By Hua Lu,Bin Yang,Christian S. Jensen
Issue Date:April 2011
pp. 816-827
To facilitate a variety of applications, positioning systems are deployed in indoor settings. For example, Bluetooth and RFID positioning are deployed in airports to support real-time monitoring of delays as well as off-line flow and space usage analyses. ...
 
Techniques for Efficient Road-Network-Based Tracking of Moving Objects
Found in: IEEE Transactions on Knowledge and Data Engineering
By Alminas Civilis, Christian S. Jensen, Stardas Pakalnis
Issue Date:May 2005
pp. 698-712
With the continued advances in wireless communications, geo-positioning, and consumer electronics, an infrastructure is emerging that enables location-based services that rely on the tracking of the continuously changing positions of entire populations of ...
 
Effective Privacy-Preserving Online Route Planning
Found in: Mobile Data Management, IEEE International Conference on
By Carmen Ruiz Vicente,Ira Assent,Christian S. Jensen
Issue Date:June 2011
pp. 119-128
An online Route Planning Service (RPS) computes a route from one location to another. Current RPSs such as Google Maps require the use of precise locations. However, some users may not want to disclose their source and destination locations due to privacy ...
 
Using the Lock Manager to Choose Timestamps
Found in: Database Engineering and Applications Symposium, International
By David Lomet, Richard T. Snodgrass, Christian S. Jensen
Issue Date:July 2005
pp. 357-368
Our goal is to support transaction-time functionality that enables the coexistence of ordinary, non-temporal tables with transaction-time tables. In such a system, each transaction updating a transaction-time or snapshot table must include a timestamp for ...
 
Light-Weight Indexing of General Bitemporal Data
Found in: Scientific and Statistical Database Management, International Conference on
By Rasa Bliujute, Christian S. Jensen, Simonas Šaltenis, Giedrius Slivinskas
Issue Date:July 2000
pp. 125
Most data managed by existing, real-world database applications is time referenced. Often, two temporal aspects of data are of interest, namely valid time, when data is true in the mini-world, and transaction time, when data is current in the database, res...
 
Skyline Queries Against Mobile Lightweight Devices in MANETs
Found in: Data Engineering, International Conference on
By Zhiyong Huang, Christian S. Jensen, Hua Lu, Beng Chin Ooi
Issue Date:April 2006
pp. 66
Skyline queries are well suited when retrieving data according to multiple criteria. While most previous work has assumed a centralized setting this paper considers skyline querying in a mobile and distributed setting, where each mobile device is capable o...
 
Joint Top-K Spatial Keyword Query Processing
Found in: IEEE Transactions on Knowledge and Data Engineering
By Dingming Wu,Man Lung Yiu,Gao Cong,Christian S. Jensen
Issue Date:October 2012
pp. 1889-1903
Web users and content are increasingly being geopositioned, and increased focus is being given to serving local content in response to web queries. This development calls for spatial keyword queries that take into account both the locations and textual des...
 
Efficient Cost-Based Tracking of Scheduled Vehicle Journeys
Found in: Mobile Data Management, IEEE International Conference on
By Dalia Tiešyte, Christian S. Jensen
Issue Date:April 2008
pp. 9-16
Applications in areas such as logistics, cargo delivery, and collective transport involve the management of fleets of vehicles that are expected to travel along known routes??according to schedules. There is a fundamental need by the infrastructure surroun...
 
A Foundation for Conventional and Temporal Query Optimization Addressing Duplicates and Ordering
Found in: IEEE Transactions on Knowledge and Data Engineering
By Giedrius Slivinskas, Christian S. Jensen, Richard T. Snodgrass
Issue Date:January 2001
pp. 21-49
<p><b>Abstract</b>—Most real-world databases contain substantial amounts of time-referenced, or temporal, data. Recent advances in temporal query languages show that such database applications may benefit substantially from built-in tempo...
 
Incremental Join of Time-Oriented Data
Found in: Scientific and Statistical Database Management, International Conference on
By Dieter Pfoser, Christian S. Jensen
Issue Date:July 1999
pp. 232
Data warehouses as well as a wide range of other databases exhibit a strong temporal orientation: it is important to track the temporal variation of data over several months or years. In addition, databases often exhibit append-only characteristics where o...
 
Continuous Clustering of Moving Objects
Found in: IEEE Transactions on Knowledge and Data Engineering
By Christian S. Jensen, Dan Lin, Beng Chin Ooi
Issue Date:September 2007
pp. 1161-1174
This paper considers the problem of efficiently maintaining a clustering of a dynamic set of data points that move continuously in two-dimensional Euclidean space. This problem has received little attention and introduces new challenges to clustering. The ...
 
Cooperative Scalable Moving Continuous Query Processing
Found in: 2012 13th IEEE International Conference on Mobile Data Management (MDM)
By Xiaohui Li,Panagiotis Karras,Lei Shi,Kian-Lee Tan,Christian S. Jensen
Issue Date:July 2012
pp. 69-78
A range of applications call for a mobile client to continuously monitor others in close proximity. Past research on such problems has covered two extremes: It has offered totally centralized solutions, where a server takes care of all queries, and totally...
 
Challenges in the Tracking and Prediction of Scheduled-Vehicle Journeys
Found in: Pervasive Computing and Communications Workshops, IEEE International Conference on
By Dalia Tiesyte, Christian S. Jensen
Issue Date:March 2007
pp. 407-412
A number of applications in areas such as logistics, cargo delivery, and collective transport involve the management of fleets of vehicles that are expected to travel along known routes according to fixed schedules. Due to road construction, accidents, and...
 
Efficient Tracking of Moving Objects with Precision Guarantees
Found in: Mobile and Ubiquitous Systems, Annual International Conference on
By Alminas Čivilis, Christian S. Jensen, Jovita Nenortaitė, Stardas Pakalnis
Issue Date:August 2004
pp. 164-173
<p>Sustained advances in wireless communications, geo-positioning, and consumer electronics pave the way to a kind of location-based service that relies on the tracking of the continuously changing positions of an entire population of service users. ...
 
Indexing of Moving Objects for Location-Based Services
Found in: Data Engineering, International Conference on
By Simonas Šaltenis, Christian S. Jensen
Issue Date:March 2002
pp. 0463
Visionaries predict that the Internet will soon extend to billions of wireless devices, or objects, a substantial fraction of which will offer their changing positions to location-based services. This paper assumes an Internet-service scenario where object...
 
Query Plans for Conventional and Temporal Queries Involving Duplicates and Ordering
Found in: Data Engineering, International Conference on
By Giedrius Slivinskas, Christian S. Jensen, Richard T. Snodgrass
Issue Date:March 2000
pp. 547
No summary available.
 
Effective Online Group Discovery in Trajectory Databases
Found in: IEEE Transactions on Knowledge and Data Engineering
By Xiaohui Li,Vaida Ceikute,Christian S. Jensen,Kian-Lee Tan
Issue Date:December 2013
pp. 2752-2766
GPS-enabled devices are pervasive nowadays. Finding movement patterns in trajectory data stream is gaining in importance. We propose a group discovery framework that aims to efficiently support the online discovery of moving objects that travel together. T...
 
User-Generated Content: The Case for Mobile Services
Found in: Computer
By Christian S. Jensen, Carmen Ruiz Vicente, Rico Wind
Issue Date:December 2008
pp. 116-118
Enabling user-generated services could help fuel the mobile revolution.
 
Efficient continuously moving top-k spatial keyword query processing
Found in: Data Engineering, International Conference on
By Dingming Wu,Man Lung Yiu,Christian S. Jensen,Gao Cong
Issue Date:April 2011
pp. 541-552
Web users and content are increasingly being geo-positioned. This development gives prominence to spatial keyword queries, which involve both the locations and textual descriptions of content.
 
Location-Related Privacy in Geo-Social Networks
Found in: IEEE Internet Computing
By Carmen Ruiz Vicente, Dario Freni, Claudio Bettini, Christian S. Jensen
Issue Date:May 2011
pp. 20-27
<p>Geo-social networks (GeoSNs) provide context-aware services that help associate location with users and content. The proliferation of GeoSNs indicates that they're rapidly attracting users. GeoSNs currently offer different types of services, inclu...
 
Identifying Typical Movements among Indoor Objects -- Concepts and Empirical Study
Found in: 2013 14th IEEE International Conference on Mobile Data Management (MDM)
By Laura Radaelli,Dovydas Sabonis,Hua Lu,Christian S. Jensen
Issue Date:June 2013
pp. 197-206
With the proliferation of mobile computing, positioning systems are becoming available that enable indoor location-based services. As a result, indoor tracking data is also becoming available. This paper puts focus on one use of such data, namely the ident...
 
Nearest Neighbor and Reverse Nearest Neighbor Queries for Moving Objects
Found in: Database Engineering and Applications Symposium, International
By Rimantas Benetis, Christian S. Jensen, Gytis Karčiauskas, Simonas Šaltenis
Issue Date:July 2002
pp. 44
<p>With the proliferation of wireless communications and the rapid advances in technologies for tracking the positions of continuously moving objects, algorithms for efficiently answering queries about large numbers of moving objects increasingly are...
 
EcoTour: Reducing the Environmental Footprint of Vehicles Using Eco-routes
Found in: 2013 14th IEEE International Conference on Mobile Data Management (MDM)
By Ove Andersen,Christian S. Jensen,Kristian Torp,Bin Yang
Issue Date:June 2013
pp. 338-340
Reduction in greenhouse gas emissions from transportation is essential in combating global warming and climate change. Eco-routing enables drivers to use the most eco-friendly routes and is effective in reducing the emissions from vehicular transportation....
 
Hybrid Indoor Positioning with Wi-Fi and Bluetooth: Architecture and Performance
Found in: 2013 14th IEEE International Conference on Mobile Data Management (MDM)
By Artur Baniukevic,Christian S. Jensen,Hua Lu
Issue Date:June 2013
pp. 207-216
Reliable indoor positioning is an important foundation for emerging indoor location based services. Most existing indoor positioning proposals rely on a single wireless technology, e.g., Wi-Fi, Bluetooth, or RFID. A hybrid positioning system combines such ...
 
Outsourced Similarity Search on Metric Data Assets
Found in: IEEE Transactions on Knowledge and Data Engineering
By Man Lung Yiu,Ira Assent,Christian S. Jensen,Panos Kalnis
Issue Date:February 2012
pp. 338-352
This paper considers a cloud computing setting in which similarity querying of metric data is outsourced to a service provider. The data is to be revealed only to trusted users, not to the service provider or anyone else. Users query the server for the mos...
 
Seamless Indoor/Outdoor Positioning Handover for Location-Based Services in Streamspin
Found in: Mobile Data Management, IEEE International Conference on
By René Hansen, Rico Wind, Christian S. Jensen, Bent Thomsen
Issue Date:May 2009
pp. 267-272
This paper presents the implementation of a novel seamless indoor/outdoor positioning service for mobile users.The service is being made available in the Streamspin system(www.streamspin.com), an open platform for the creation and delivery of location-base...
 
Multidimensional Data Modeling for Complex Data
Found in: Data Engineering, International Conference on
By Torben Bach Pedersen, Christian S. Jensen
Issue Date:March 1999
pp. 336
No summary available.
 
Using Incomplete Information for Complete Weight Annotation of Road Networks
Found in: IEEE Transactions on Knowledge and Data Engineering
By Bin Yang,Manohar Kaul,Christian S. Jensen
Issue Date:May 2014
pp. 1-1
We are witnessing increasing interests in the effective use of road networks. For example, to enable effective vehicle routing, weighted-graph models of transportation networks are used, where the weight of an edge captures some cost associated with traver...
 
Building Accurate 3D Spatial Networks to Enable Next Generation Intelligent Transportation Systems
Found in: 2013 14th IEEE International Conference on Mobile Data Management (MDM)
By Manohar Kaul,Bin Yang,Christian S. Jensen
Issue Date:June 2013
pp. 137-146
The use of accurate 3D spatial network models can enable substantial improvements in vehicle routing. Notably, such models enable eco-routing, which reduces the environmental impact of transportation. We propose a novel filtering and lifting framework that...
 
Routing Service Quality -- Local Driver Behavior Versus Routing Services
Found in: 2013 14th IEEE International Conference on Mobile Data Management (MDM)
By Vaida Ceikute,Christian S. Jensen
Issue Date:June 2013
pp. 97-106
Mobile location-based services is a very successful class of services that are being used frequently by users with GPS-enabled mobile devices such as smartphones. This paper presents a study of how to exploit GPS trajectory data, which is available in incr...
 
Querying the Web with Local Intent
Found in: 2013 14th IEEE International Conference on Mobile Data Management (MDM)
By Christian S. Jensen
Issue Date:June 2013
pp. 1
No summary available.
 
A Foundation for Efficient Indoor Distance-Aware Query Processing
Found in: Data Engineering, International Conference on
By Hua Lu,Xin Cao,Christian S. Jensen
Issue Date:April 2012
pp. 438-449
Indoor spaces accommodate large numbers of spatial objects, e.g., points of interest (POIs), and moving populations. A variety of services, e.g., location-based services and security control, are relevant to indoor spaces. Such services can be improved sub...
 
Improving Wi-Fi Based Indoor Positioning Using Bluetooth Add-Ons
Found in: Mobile Data Management, IEEE International Conference on
By Artur Baniukevic,Dovydas Sabonis,Christian S. Jensen,Hua Lu
Issue Date:June 2011
pp. 246-255
Location-Based Services (LBSs) constitutes one of the most popular classes of mobile services. However, while current LBSs typically target outdoor settings, we lead large parts of our lives indoors. The availability of easy-to-use and low-cost indoor posi...
 
SpaceTwist: Managing the Trade-Offs Among Location Privacy, Query Performance, and Query Accuracy in Mobile Services
Found in: Data Engineering, International Conference on
By Man Lung Yiu, Christian S. Jensen, Xuegang Huang, Hua Lu
Issue Date:April 2008
pp. 366-375
In a mobile service scenario, users query a server for nearby points of interest but they may not want to disclose their locations to the service. Intuitively, location privacy may be obtained at the cost of query performance and query accuracy. The challe...
 
A Testbed for the Exploration of Novel Concepts in Mobile Service Delivery
Found in: Mobile Data Management, IEEE International Conference on
By Rico Wind, Christian S. Jensen, Kenneth H. Pedersen, Kristian Torp
Issue Date:May 2007
pp. 218-220
No summary available.
 
Multidimensional Database Technology
Found in: Computer
By Torben Bach Pedersen, Christian S. Jensen
Issue Date:December 2001
pp. 40-46
<p>Multidimensional data-base technology is a key factor in the interactive analysis of large amounts of data for decision-making purposes. In contrast to previous technologies, these databases view data as multidimensional cubes that are particularl...
 
GPU-Based Computing of Repeated Range Queries over Moving Objects
Found in: 2014 22nd Euromicro International Conference on Parallel, Distributed and Network-Based Processing (PDP)
By Claudio Silvestri,Francesco Lettich,Salvatore Orlando,Christian S. Jensen
Issue Date:February 2014
pp. 640-647
In this paper we investigate the use of GPUs to solve a data-intensive problem that involves huge amounts of moving objects. The scenario which we focus on regards objects that continuously move in a 2D space, where a large percentage of them also issues r...
 
Graph Model Based Indoor Tracking
Found in: Mobile Data Management, IEEE International Conference on
By Christian S. Jensen, Hua Lu, Bin Yang
Issue Date:May 2009
pp. 122-131
The tracking of the locations of moving objects in large indoor spaces is important, as it enables a range of applications related to, e.g., security and indoor navigation and guidance. This paper presents a graph model based approach to indoor tracking th...
 
Emotion-based music retrieval on a well-reduced audio feature space
Found in: Acoustics, Speech, and Signal Processing, IEEE International Conference on
By Maria M. Ruxanda, Bee Yong Chua, Alexandros Nanopoulos, Christian S. Jensen
Issue Date:April 2009
pp. 181-184
Music expresses emotion. A number of audio extracted features have influence on the perceived emotional expression of music. These audio features generate a high-dimensional space, on which music similarity retrieval can be performed effectively, with resp...
 
Routing Questions to the Right Users in Online Communities
Found in: Data Engineering, International Conference on
By Yanhong Zhou, Gao Cong, Bin Cui, Christian S. Jensen, Junjie Yao
Issue Date:April 2009
pp. 700-711
Online forums contain huge amounts of valuable user-generated content. In current forum systems, users have to passively wait for other users to visit the forum systems and read/answer their questions. The user experience for question answering suffers fro...
 
Robust B+-Tree-Based Indexing of Moving Objects
Found in: Mobile Data Management, IEEE International Conference on
By Christian S. Jensen, Dalia Tie¡sytïe, Nerius Tradi¡sauskas
Issue Date:May 2006
pp. 12
With the emergence of an infrastructure that enables the geo-positioning of on-line, mobile users, the management of so-called moving objects has emerged as an active area of research. Among the indexing techniques for efficiently answering predictive quer...
 
Management of Multiply Represented Geographic Entities
Found in: Database Engineering and Applications Symposium, International
By Anders Friis-Christensen, David Skogan, Christian S. Jensen, Gerhard Skagestein, Nectaria Tryfona
Issue Date:July 2002
pp. 150
Multiple representation of geographic information occurs when a real-world entity is represented more than once in the same or different databases. In this paper, we propose a new approach to the modeling of multiply represented entities and the relationsh...
 
Supporting Imprecision in Multidimensional Databases Using Granularities
Found in: Scientific and Statistical Database Management, International Conference on
By Torben Bach Pedersen, Christian S. Jensen, Curtis E. Dyreson
Issue Date:July 1999
pp. 90
On-Line Analytical Processing (OLAP) technologies are being used widely, but the lack of effective means of handling data imprecision, which occurs when exact values are not known precisely or are entirely missing, represents a major obstacle in applying t...
 
Temporal Entity-Relationship Models-A Survey
Found in: IEEE Transactions on Knowledge and Data Engineering
By Heidi Gregersen, Christian S. Jensen
Issue Date:May 1999
pp. 464-497
<p><b>Abstract</b>—The Entity-Relationship (ER) model, using varying notations and with some semantic variations, is enjoying a remarkable, and increasing, popularity in both the research community—the computer science curriculum—and in i...
 
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