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—We deployed 72 sensors of 10 modalities in 15 wireless and wired networked sensor systems in the environment, in objects, and on the body to create a sensor-rich environment for the machine recognition of human activities. We acquired data from 12 subjects performing morning activities, yielding over 25 hours of sensor data. We report the number of(More)
In this paper, we present an implemented system for supporting group interaction in mobile distributed computing environments. First, an introduction to context computing and a motivation for using contextual information to facilitate group interaction is given. We then present the architecture of our system, which consists of two parts: a subsystem for(More)
The emerging availability of already deployed sensors that can be utilized for activity and context recognition raised a new paradigm. This paradigm called opportunistic sensing utilizes the available sensing infrastructure for activity and context recognition. This work focuses on utilizing this dynamically varying infrastructure to recognize high-level(More)
In an attempt to cope with time-varying workload, traditional adaptive Time Warp protocols are designed to react in response to performance changes by altering control parameter configurations, like the amount of available memory, the size of the checkpointing interval, the frequency of GVT computation, fossil collection invocations, etc.\ We call those(More)
Current mobile devices like mobile phones or personal digital assistants have become more and more powerful; they already offer features that only few users are able to exploit to their whole extent. With a number of upcoming mobile multimedia applications, ease of use becomes one of the most important aspects. One way to improve usability is to make(More)
The main performance pitfall of the Time Warp distributed discrete event simulation (DDES) protocol has been widely recognized to be the overoptimistic progression of event execution into the simulated future. The premature execution of events that eventually have to be \rolled back" due to causality violations induces memory and communication overheads as(More)
The Petri net formalism, due to its graphical modeling support and profound mathematical background, has been successfully used in the analysis of systems that obey concurrency, synchronization, mutual exclusion and nondeterminism. Computerized tools supporting the model development process and automating the analysis are available today. In this work we(More)