PriCal is an ambient calendar display that shows a user's schedule similar to a paper wall calendar. PriCal provides context-adaptive privacy to users by detecting present persons and adapting event visibility according to the user's privacy preferences. We present a detailed privacy impact assessment of our system, which provides insights on how to leverage context to enhance privacy without being intrusive. PriCal is based on a decentralized architecture and supports the detection of registered users as well as unknown persons. In a three-week deployment study with seven displays, ten participants used PriCal in their real work environment with their own digital calendars. Our results provide qualitative insights on the implications, acceptance, and utility of context-adaptive privacy in the context of a calendar display system, indicating that it is a viable approach to mitigate privacy implications in ubicomp applications.

There are many potential applications for very high-speed vision sensors in robotics. Maybe tracking is the most obvious one. The main idea of this paper is to combine existing standard technology (CMOS imaging sensors, FPGA "glue logic", and USB 2.0 interface) to use direct pixel access capabilities for real-time tracking. We designed and built such a prototype camera system, including FPGA programmed functionality for Fixed Pattern Noise (FPN) calibration, subsampling and direct subwindow access. The performance of this new camera is on one hand limited by the maximum pixel clock of the sensor, on the other hand by the USB 2.0 microframe timing and bandwith constraints. We achieve "frame rates" of up to 2.5 kHz for small subwindows which can be randomly and individually addressed for each update cycle. Besides all given technical details and specifications of the system, we show a demonstration application of a high-speed blob tracking system which verifies the usability of our new camera for highly demanding tracking applications.

At the conceptual level, business rules are formulated from an external observation perspective according to the event-condition-action structure of rules in active database systems. Situation/activation diagrams homogeneously extend object/behavior diagrams to a graphical notation for the conceptual design of business objects and their associated business rules. Situation diagrams provide a high-level representation of logical events. Activation diagrams specify graphically which activities have to be performed upon some triggering event if an associated condition is satisfied. The developed editor supports both object/behavior diagrams and situation/activation diagrams. The editor performs syntactic consistency checks during the interactive design process. Moreover, by building the logical model in parallel with the diagrams, the editor guarantees that local semantic consistency checks can be performed incrementally, too. The editor clearly separates between schema data and pure visualization data describing the location of diagram elements. This separation facilitates the reuse of the generated data for further processing. Both schema data and visualization data are stored in the commercial object-oriented database system GemStone. Alternatively, those data may be stored in a file. The editor has been implemented using VisualWorks and MetaDoME, a framework for building graphical editors with VisualWorks.

Business rules are statements about business policies and can be formulated according to the event-condition-action (ECA) structure of rules in active database systems. However, modeling business rules at the conceptual level from an external user's perspective requires a different set of concepts than currently provided by active database systems. This paper identifies requirements on the event language and on the semantics of rule execution for modeling business rules and presents a graphical object-oriented language, called situation/activation diagrams, meeting these requirements.