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In this paper, we address the data management aspect of large-scale pervasive computing systems. We aim at building an infrastructure that simultaneously supports many kinds of context-aware applications, ranging from room level up to nation level. This all-embracing approach gives rise to synergetic benefits like data reuse and sensor sharing. We identify(More)
Meta data - data about data - improves the value of the operational data by giving applications and users additional information on the data's origin, its precision or staleness. We outline the benefits of modeling meta data in context models: it can be used for resource finding, enhanced data selection, trust and data quality issues and sensor fusion. We(More)
Context-aware applications rely on models of the physical world. Within the Nexus project, we envision a World Wide Space which provides the conceptual and technological framework for integrating and sharing such context models in an open, global platform of context providers. In our ongoing research we tackle important challenges in such a platform(More)
In order to allow blind people independent navigation in unknown areas, we have developed a navigation system that seamlessly integrates both static maps and dynamic location-based textual information from a variety of sources. Each information source requires a different kind of acquisition technique. The acquired information is integrated by a context(More)
We present the design and implementation of a component for the preprocessing of position data taken from moving objects. The movement of mobile objects is represented by piece wise functions over time that approximate the real object movement and significantly reduce the initial data volume such that efficient storage and analysis of object trajectories(More)
Rule-based context reasoning is an expressive way to define situations, which are crucial for the implementation of many context-aware applications. Along the scenario of the Conference Guard application we show how this reasoning can be done both by leveraging an efficient context management (realized by the Nexus platform) and by a generic rule based(More)
Techniques for efficient and distributed processing of huge, unbound data streams have made some impact in the database community. Sensors and data sources, such as position data of moving objects, continuously produce data that is consumed, e.g., by location-aware applications. Depending on the domain of interest, e.g. visualization, the processing of such(More)
With the increasing use of sensor technology, the compression of sensor data streams is getting more and more important to reduce both the costs of further processing as well as the data volume for persistent storage. A popular method for sensor data compression is to smooth the original measurement curve by an approximated curve, which is bounded by a(More)
This demo shows several advanced use cases of location-based services and demonstrates how these use cases are facilitated by a mediation middleware for spatial information, the Nexus Platform. The scenario shows how a mobile user can access location-based information via so called Virtual Information Towers, register spatial events, send and receive(More)