Fredrik Kilander

A Ubiquitous Service Environment with Active Documents for Teamwork Support

We present a ubiquitous service environment for teamwork, supported by Active Documents. The environment consists of a physically dressed conference room and a software architecture based on Java and Jini. At the application level, mobile agent technology provide Active Documents that utilize context information and distributed resources to support users. We also present a prototype and preliminary results from observations in a meeting scenario.

COBBIT - A Control Procedure for COBWEB in the Presence of Concept Drift

This paper is concerned with the robustness of concept formation systems in the presence of concept drift. By concept drift is meant that the intension of a concept is not stable during the period of learning, a restriction which is otherwise often imposed. The work is based upon the architecture of COBWEB, an incremental, probabilistic conceptual clustering system. When incrementally and sequentially exposed to the extensions of a set of concepts, COBWEB retains all examples, disregards the age of a concept and may create different conceptual structures dependent on the order of examples. These three characteristics make COBWEB sensitive to the effects of concept drift. Six mechanisms that can detect concept drift and adjust the conceptual structure are proposed. A variant of one of these mechanisms: dynamic deletion of old examples, is implemented in a modified COBWEB system called COBBIT. The relative performance of COBWEB and COBBIT in the presence of concept drift is evaluated. In the experiment the error index, i.e. the average of the ability to predict each attribute is used as the major instrument. The experiment is performed in a synthetical domain and indicates that COBBIT regain performance faster after a discrete concept shift.

Extending Instant Messaging to Provide Pervasive Personal Communication

This paper proposes a personal software architecture to provide a user with a pervasive communication capability. The core of this architecture is a personal communication server (PCS) which bridges between different instant messaging networks and extends them with a unified access to the user. A SIP-based implementation of such a communication server is presented, which solves various interoperability problems, and also provides many value-added features, e.g., extended user presence with location information, adaptive communication, better privacy protection, etc. This implementation enables various existing SIP-compatible resources to be re-used and thus simplifies the construction of the proposed software architecture

Building infrastructure support for ubiquitous context-aware systems

Many context-aware systems have been demonstrated in lab environments; however, due to some difficulties such as the scalability and privacy issues, they are not yet practical for deployment on a large scale. This paper addresses these two issues with particular interest in users privacy protection and spontaneous system association. A person-centric service infrastructure is proposed together with a context-aware call forwarding system constructed as a proof-of-concept prototype based on the Session Initiation Protocol (SIP).

Context middleware for adaptive services in heterogeneous wireless networks

This paper provides an overview of important results and work-in-progress within the ACAS project concerning context middleware to enable adaptive, user-centric, mobile services available to users via a heterogeneous wireless infrastructure.