Georg Lehrenfeld

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Understanding and debugging of concurrent systems is a critical activity in systems design. Means supporting the visual inspection of drawings as well as the animation of the execution are expected to play a signi cant role in future. Since Pictorial Janus (PJ) has been de ned as a completely visual language including an advanced animation semantics it(More)
This article investigates the integration of an interactive constraint solver into an existing 2–D real–time animation environment in order to achieve a better observability, traceability, and stability of the individual graphical objects. We present two approaches for assigning constraints to the objects. The first approach assigns constraints to the(More)
We present a new approach to an interactive design and analysis environment for visual languages. The main components, i.e., editor, animator, and interpreter, are introduced. Their interactions are being investigated emphasizing the interpreter–animator interaction and defining an interface supporting different levels of automation. The interpreter(More)
Main goal of this contribution is a first approach to evaluate the suitability of visual programming languages, i.e., Pictorial Janus [3], for the modeling of complex systems and their control strategies. These systems can be seen as networks of communicating objects. Objects select strategies for suitable actions based on incoming messages. Our field of(More)
3D-graphics become popular in a steadily increasing number of areas like entertainment, scientiic visual-ization, simulation, and virtual reality. Despite this rapid growth the generation of animated 3D scenes is still by no means trivial. Since animated 3D objects evolve over time we denote these objects as 4D. This article presents a novel approach to the(More)
1 Introduction Today's embedded systems (ES) are characterized by more and more parallelism, distribution over different locations and hard real-time (RT) requirements. Consequently, the modern, structured design process has to deal with heterogeneous requirements and restrictions. Especially the integration of HW-design tasks with SW-design tasks and(More)
In this article we present a new approach for the design of hybrid systems composed of discrete and continuous parts. In our approach the system designers can start their speciications with the discrete as well as with the continuous parts. Both paradigms can be used with there own methodology and Tools. There are integration mechanisms for both paradigms.(More)
ISO 10303 de nes standards for the international STEP (Standard for the Exchange of Product Model Data) e ort for the machine-independent exchange of product data between di erent computer systems. Part 21 of ISO 10303 [ISO10303-21] de nes an exchange structure. The schema of this format is speci ed in the EXPRESS language [ISO10303-11]. EXPRESS can be(More)