ln Memoriam Kathleen Ptolemy

Kathleen Early

Memoriam.

George W. Housner, Carl F Braun Professor of Engineering, emeritus, died after a short illness on 10 November 2008, just a few weeks before his 98th birthday. He was in the retirement home in Pasadena where he had lived for several years. For all of us who knew George, this marked the end of an era. Few people have guided and nurtured a field the way George led earthquake engineering over a per...

Dr. Kathleen Iles

Systems Modeling in Ptolemy

Synchronous Dataflow (SDF) is useful in modeling communications and signal processing systems. We describe a communication actor library based on the SDF semantics in Ptolemy II and show how to use these actors to simulate communication systems. However, many communication and signal processing systems nowadays use adaptive algorithms and control protocols. These sometimes violate SDF principle...

Modal Models in Ptolemy

Ptolemy is an open-source and extensible modeling and simulation framework. It offers heterogeneous modeling capabilities by allowing different models of computation to be composed hierarchically in an arbitrary fashion. This paper describes modal models, which allow to hierarchically compose finite-state machines with other models of computation, both untimed and timed. The semantics of modal ...