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Bond graph modelling was devised by Professor Paynter at the Massachusetts Institute of Technology in 1959 and subsequently developed into a methodology for modelling multidisciplinary systems at a time when nobody was speaking of object-oriented modelling. On the other hand, so-called object-oriented modelling has become increasingly popular during the last few years. By relating the characteristics of both approaches, it is shown that bond graph modelling, although much older, may be viewed as a special form of object-oriented modelling. For that purpose the new object-oriented modelling language Modelica is used as a working language which aims at supporting multiple formalisms. Although it turns out that bond graph models can be described rather easily, it is obvious that Modelica started from generalized networks and was not designed to support bond graphs. The description of bond graph models in Modelica is illustrated by means of a hydraulic drive. Since VHDL-AMS as an important language standardized and supported by IEEE has been extended to support also modelling of non-electrical systems, it is briefly investigated as to whether it can be used for description of bond graphs. It turns out that currently it does not seem to be suitable.
Multidisciplinary systems are described most suitably by bond graphs. In order to determine unnormalized frequency domain sensitivities in symbolic form, this paper proposes to construct in a systematic manner a bond graph from another bond graph, which is called the associated incremental bond graph in this paper. Contrary to other approaches reported in the literature the variables at the bonds of the incremental bond graph are not sensitivities but variations (incremental changes) in the power variables from their nominal values due to parameter changes. Thus their product is power. For linear elements their corresponding model in the incremental bond graph also has a linear characteristic. By deriving the system equations in symbolic state space form from the incremental bond graph in the same way as they are derived from the initial bond graph, the sensitivity matrix of the system can be set up in symbolic form. Its entries are transfer functions depending on the nominal parameter values and on the nominal states and the inputs of the original model. The sensitivities can be determined automatically by the bond graph preprocessor CAMP-G and the widely used program MATLAB together with the Symbolic Toolbox for symbolic mathematical calculation. No particular program is needed for the approach proposed. The initial bond graph model may be non-linear and may contain controlled sources and multiport elements. In that case the sensitivity model is linear time variant and must be solved in the time domain. The rationale and the generality of the proposed approach are presented. For illustration purposes a mechatronic example system, a load positioned by a constant-excitation d.c. motor, is presented and sensitivities are determined in symbolic form by means of CAMP-G/MATLAB.
Im vorliegenden Beitrag wird ein prozess- und serviceorientiertes Rahmenmodell vorgeschlagen, das eine strukturelle und begriffliche Orientierung für das Gebiet der elektronischen Bezahlung bietet. Das Rahmenmodell erlaubt eine ganzheitliche Betrachtung über die Merkmale eines einzelnen Zahlungssystems hinaus. Die systemspezifische Sicht auf die elektronische Zahlung wird zu einem prozessorientierten Phasenmodell verallgemeinert. Mit diesem lassen sich die unterstützenden Services für die elektronische Bezahlung aus Kunden- und Händlersicht systematisch zusammenstellen und beschreiben. Die organisatorische Umsetzung der Serviceprozesse führt zur Rolle des Payment Service Providers, der als Mittler zwischen Anbietern und Anwendern elektronischer Zahlungssysteme agiert.
Finding good Echo State Networks to control an underwater robot using evolutionary computations
(2004)
RFID security
(2004)
Honeypots und Honeynets
(2004)