3D geodata are more and more available as well as realtime visualization possibilities with free three-dimensional viewers such as Google Earth. This implies a growing demand of 3D city models, which are 3D representations at the scale of the city. Despite their intended wide range of applications, such models cannot be used for many urban tasks as they cannot represent the urban information associated with these tasks. On the contrary, ontologies have proven their capacity and usability in the representation of information and knowledge of various domains. In this paper we will present, on the basis of case studies, how ontologies can overstep the semantic limitation of 3D city models and how ontology-based models can be interconnected thus increasing the interoperability of urban information.
There exist many popular crowdsourcing and social services (Volunteered Geographic Information (VGI)) to share information and documents such as Flickr, Foursquare, Twitter , Facebook, etc. They all use metadata, folksonomy and more importantly a geographic axis with GPS coordinates and/or geographic tags. Using this available folksonomy in VGI services we propose a logical approach to highlight and possibly discover the characteristics of geographic places. The approach is based on the notion of spatial coverage and a model of tags categorization and on their semantic identification, using semantic services such as GeoNames, OpenStreetMap or WordNet. We illustrate our model with Flickr to retrieve the characteristics (function, usage?) of places even if those places have a small number of related photos. Those found characteristics allow tag disambiguation and can be use to complete the semantic gap on places and POIs such as the function of buildings, which can exist in geographic services.
We consider an infinite-horizon exchange economy with incomplete markets and collateral constraints. As in the two-period model of Geanakoplos and Zame (2002), households can default on their liabilities at any time, and financial securities are only traded if the promises associated with these securities are backed by collateral. We examine an economy with a single perishable consumption good, where the only collateral available consists of productive assets. In this model, competitive equilibria always exist and we show that, under the assumption that all exogenous variables follow a Markov chain, there also exist stationary equilibria. These equilibria can be characterized by a mapping from the exogenous shock and the current distribution of financial wealth to prices and portfolio choices. We develop an algorithm to approximate this mapping numerically and discuss ways to implement the algorithm in practice. A computational example demonstrates the performance of the algorithm and shows some quantitative features of equilibria in a model with collateral and default.
Health care is one of the most prominent areas for the application of wireless technologies. New services and applications are today under research and development targeting different areas of health care, from high risk and chronic patients' remote monitoring to mobility tools for the medical personnel. In this direction the MobiHealth1 project developed and trailed a system and a service that is using UMTS for the continuous monitoring and transmission of vital signals, like Pulse Oximeter sensor , temperature, Marker, Respiratory band, motion/activity detector etc., to the hospital. The system, based on the concept of the Body Area Network, is highly customisable, allowing sensors to be seamlessly connected and transmit the monitored vital signal measurements. The system and service was trialed in 4 European countries and it is presently under market validation.
The features of a database system specifically designed to support evolution are presented. The design of the F2 system has been deliberately directed toward integration of evolution features and the flexibility of structures at every level. This has leaded to an architecture where the meta-circular organization of the objects management is not an aesthetic facet but a concrete property of the system.
Many applications require the capability to define and manipulate a collection of related objects as a single unit. Object-oriented database models and systems usually provide the concept of composite object for that purpose. The concept of context that we propose here provides another, more general, way to view and manipulate collections of objects. We compare the two concepts both in their formal definitions and in their implementation in object-oriented database system.
