Abstract

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Abstract

Abstract
Multimedia databases are extending the scope of traditional databases to handle the complex structure of multimedia objects. Models for multimedia information must include representations for the structure and content of several media in a form that allows flexibility in retrieval. Content-based retrieval is the main motivation behind recent research in multimedia databases. The task of searching in video and audio content is made hard by the nature of audiovisual data where, unlike text, there is no direct syntactic channel between the object and its meaning [1]-[3]. We propose a model for multimedia content storage and retrieval accounting for both context and content information and taking advantage of their dependencies for effective retrieval. We then describe a prototype multimedia database with a retrieval interface. It has been used as a workbench for testing the representation model and integrating tools for feature extraction, information interchange and retrieval. The workbench allows an easy inclusion of new tools for content analysis and new methods for context- and content-based retrieval while offering storage and access for both the actual digital content and its metadata.

Abstract
Nesting problems are particularly hard combinatorial problems. They involve the positioning of a set of small arbitrarily-shaped pieces on a large stretch of material, without overlapping them. The problem constraints are bidimensional in nature and have to be imposed on each pair of pieces. This all-to-all pattern results in a quadratic number of constraints. Constraint programming has been proven applicable to this category of problems, particularly in what concerns exploring them to optimality. But it is not easy to get effective propagation of the bidimensional constraints represented via finite-domain variables. It is also not easy to achieve incrementality in the search for an improved solution: an available bound on the solution is not effective until very late in the positioning process. In the sequel of work on positioning non-convex polygonal pieces using a CLP model, this work is aimed at improving the expressiveness of constraints for this kind of problems and the effectiveness of their resolution using global constraints. A global constraint "outside" for the non-overlapping constraints at the core of nesting problems has been developed using the constraint programming interface provided by Sicstus Prolog. The global constraint has been applied together with a specialized backtracking mechanism to the resolution of instances of the problem where optimization by Integer Programming techniques is not considered viable. The use of a global constraint for nesting problems is also regarded as a first step in the direction of integrating Integer Programming techniques within a Constraint Programming model.

Abstract
This paper describes an architecture which can be used to access geographic information from mobile devices with limited display and processing characteristics, such as Personal Digital Assistants (PDA) or Mobile Phones. The information may come from different sources leading to an interoperable solution. M-GIS obtains geographic information from sources described using Geogxraphy Markup Language (GML) from one or more Web Feature Servers allowing an access independent from its format or physical location, as long as the information is according to the specification. Using XSLT, GML is transformed to a graphical format in Scalable Vector Graphics (SVG) which can then be manipulated in the mobile device. M-GIS follows a client/server architecture and the client application was developed using Java Mobile Information Device Profile technology. The results enable us to conclude that the mobile system, designed and developed with the use of open standards and representation formats to access geographic information, is a viable solution with some limitations. The main limitations of this approach have to do with the amount of information which the client can, at the moment, accommodate.