Moving Objects Databases have become an important research issue in recent years. For modeling and querying moving objects, there exists a comprehensive framework of abstract data types to describe objects moving freely in the 2D plane, providing data types such as moving point or moving region. However, in many applications people or vehicles move along transportation networks.

Any software made available via DB TECH REPORTS is provided “as is ” and without any express or implied warranties, including, without limitation, the implied warranty of merchantability and fitness for a particular purpose. The DB TECH REPORTS icon is made from two letters in an early version of the Rune alphabet, which was used by the Vikings, among others. Runes have angular shapes and lack horizontal lines because the primary storage medium was wood, although they may also be found on jewelry, tools, and weapons. Runes were perceived as having magic, hidden powers. The first letter in the logo is “Dagaz, ” the rune for day or daylight and the phonetic equivalent of “d. ” Its meanings include happiness, activity, and satisfaction. The second letter is “Berkano, ” which is associated with the birch tree. Its divinatory meanings include health, new beginnings, growth, plenty, and clearance. It is associated with Idun, goddess of Spring, and with fertility. It is the phonetic equivalent of “b.” With the continuing advances in wireless communications, geo-positioning, and portable electronics, an infrastructure is emerging that enables the delivery of on-line, location-enabled services to very large numbers of mobile users. A typical usage situation for mobile services is one characterized by a small

Much research has recently been devoted to the data management foundations of location-based mobile services. In one important scenario, the service users are constrained to a transportation network. As a result, query processing in spatial road networks is of interest. In this paper, we propose a versatile

Abstract With the continuing advances in wireless communications, geo-positioning, and portable electronics, an infrastructure is emerging that enables the delivery of on-line, location-enabled services to very large numbers of mobile users. A typical usage situation for mobile services is one characterized by a small screen and no keyboard, and by the service being only a secondary focus of the user. Under such circumstances, it is particularly important to deliver the “right ” information and service at the right time, with as little user interaction as possible. This may be achieved by making services context aware. Mobile users frequently follow the same route to a destination as they did during previous trips to the destination, and the route and destination constitute important aspects of the context for a range of services. This paper presents key concepts underlying a software component that identifies and accumulates the routes of a user along with their usage patterns and that makes the routes available to services. The problems associated with of route recording are analyzed, and algorithms that solve the problems are presented. Experiences from using the component on logs of GPS positions acquired from vehicles traveling within a real road network are reported. Keywords mobile service context · geopositioning · portable electronics · GPS positions · mobile services · location-based services · routes · destinations · context awareness

Abstract. One of the key research issues with moving objects databases (MOD) is the uncertainty management problem. In this paper, we discuss how the uncertainty of network constrained moving objects can be reduced by using reasonable modeling methods and location update policies. Besides, we present a framework to support variable accuracies in presenting the locations of moving objects. The operation design issues with uncertainty involved are also discussed. 1.

Abstract. Spatio-temporal network is defined by a set of nodes, and a set of edges, where the properties of nodes and edges may vary over time. Such networks are encountered in a variety of domains ranging from transportation science to sensor data analysis. Given a spatio-temporal network, the aim is to develop a model that is simple, expressive and storage efficient. The model must also provide support for the design of algorithms to process frequent queries that need to be answered in the application domains. This problem is challenging due to potentially conflicting requirements of model simplicity and support for efficient algorithms. Time expanded networks which have been used to model dynamic networks employ replication of the network across time instants, resulting in high storage overhead and algorithms that are computationally expensive. This model is generally used to represent time-dependent flow networks and tends to be application-specific in nature. In contrast, the proposed time-aggregated graphs do not replicate nodes and edges across time; rather they allow the properties of edges and nodes to be modeled as a time series. Our approach achieves physical data independence and also addresses the issue of modeling spatio-temporal networks that do not involve flow parameters. In this paper, we describe the model at the conceptual, logical and physical levels. We also present case studies from various application domains. 1