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  • Edward A. Lee
  • 2008
Cyber-Physical Systems (CPS) are integrations of computation and physical processes. Embedded computers and networks monitor and control the physical processes, usually with feedback loops where physical processes affect computations and vice versa. The economic and societal potential of such systems is vastly greater than what has been realized, and major(More)
hrge grain data flow (LGDF) programming is natural and convenient for describing digital signal processing (DSP) systems, but its runtime overhead is costly in real time or cost-sensitive applications. In some situations, designers are not willing to squander computing resources for the sake of programmer convenience. This is particularly true when the(More)
Many scientific disciplines are now data and information driven, and new scientific knowledge is often gained by scientists putting together data analysis and knowledge discovery " pipelines ". A related trend is that more and more scientific communities realize the benefits of sharing their data and computational services, and are thus contributing to a(More)
We review a model of computation used in industrial practice in signal processing software environments and experimentally in other contexts. We give this model the name " dataflow process networks, " and study its formal properties as well as its utility as a basis for programming language design. Variants of this model are used in commercial visual(More)
This paper presents a compile-time scheduling heuristic called dynamic level scheduling, which accounts for interprocessor communication overhead when mapping precedence-constrained, communicating tasks onto heterogeneous processor architectures with limited or possibly irregular interconnection structures. This technique uses dynamically-changing(More)
This paper builds upon research by Lee [1] concerning the token flow model, an analytical model for the behavior of dataflow graphs with data-dependent control flow, by analyzing the properties of cycles of the schedule: sequences of actor executions that return the graph to its initial state. Necessary and sufficient conditions are given for the existence(More)
1.0 ABSTRACT Ptolemy is an environment for simulation and prototyping of heterogeneous systems. It uses modern object-oriented software technology (C++) to model each subsystem in a natural and efficient manner, and to integrate these subsystems into a whole. Ptolemy encompasses practically all aspects of designing signal processing and communications(More)
Modern embedded computing systems tend to be heterogeneous in the sense of being composed of subsystems with very different characteristics, that communicate and interact in a variety of ways—synchronous or asynchronous, buffered or unbuffered, etc. Obviously, when designing such systems, a modeling language needs to reflect this het-erogeneity. Today's(More)