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- Forsman, Krister, et al.
(författare)
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FuzzyCAT - Towards a Mathematical Analysis of Fuzzy Controllers
- 1993
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Ingår i: Proceedings of the 32nd Conference on Decision and Control. - Linköping : Linköping University Electronic Press. - 0780312988 ; , s. 1284-1285 vol.2
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Konferensbidrag (refereegranskat)abstract
- The aim of this paper is to show that, contrary to what is commonly believed, it is possible to get rather simple analytic expressions for a class of fuzzy controllers. The authors describe a Maple package called FuzzyCAT that supports analysis and simulation of fuzzy controllers. The restrictions made in the program concern the shape of the membership functions, the defuzzification methods available and the number of input and output variables.
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- Isaksson, Alf, et al.
(författare)
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On Recursive Construction of Trees as Models of Dynamical Systems
- 1991
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Ingår i: Proceedings of the 30th IEEE Conference on Decision and Control. - Linköping : Linköping University. - 0780304500 ; , s. 1686-1687 vol.2
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Konferensbidrag (refereegranskat)abstract
- An issue that is of importance for control applications is discussed: how to construct the trees online, i.e. recursively, as more and more data become available. A theorem regarding recursive tree-building is stated and proved, and implementation issues are considered.
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- Persson, Lars-Erik, et al.
(författare)
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Green's method applied to the plate equation in mechanics
- 1993
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Ingår i: Annales Societatis Mathematicae Polonae. Series 1: Commentationes Mathematicae - Prace Matematyczne. - 0373-8299. ; 33, s. 119-133
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Tidskriftsartikel (refereegranskat)abstract
- This paper demonstrates existence and uniqueness of Green functions for the general fourth-order linear elliptic operator modeling the deflection of an anisotropic elastic plate with the linear boundary conditions that model the most common edge conditions. The existence theory is presented in the context of Sobolev spaces. Included is the derivation of the boundary value problem from the principles of elasticity and of the Green function for a homogeneous rectangular plate. The paper concludes with a brief discussion of qualitative properties of the Green functions. The techniques and results are classic, and the exposition is accessible to a broad audience. This paper could serve as an admirable introduction to the boundary value problems of anisotropic plates.
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- Strömberg, Jan-Erik
(författare)
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A Mode Switching Modelling Philosophy
- 1994
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The thesis presents a modelling methodology for the systematic derivation of mathematical behaviour mod els of engineering systems , i. e. systems constructed by engineers. The first part presents the theoretical and philosophical foundation underlying a dass of methods generally referred to as physical modelling. The fundamental idea is to systematically employ first principles of physics. The specific method employed here is that provided by energy-oriented bond graphs; a graphical modelling language developed by Henry M. Paynter in the late fifties. Since bond graphs are firmly grounded in fundamental laws of physics, they allow for modelling of continuous mechanisms only. From a computational point of view, this corresponds to continuous (possibly non-linear) differential and algebraic equation systems (DAES).In many practical systems though, there are rapid switching devices such as pressure relief valves, diodes, dutches, free-wheeling devices, check valves, relays et c. which are all intentionally designed to implement near ideal switching behaviour. For this dass of 'mixed' engineering systems, also referred to as mode switching systems, we would hence prefer a discontinuous idealization of the switching mechanisms. The main contribution of this thesis is an extension of the bond graph language to allow for such an idealization of mode switching systems. This extended language, here referred toas switched bond graphs is so constructed that it preserves all the essential properties of dassical bond graphs. The choice made, was to accept rather than reject the variable causality that follows as a consequence. As opposed to previous work, which focus on means to circumvent this consequence, we rather study the effects of accepting it as is. From a computational point of view, a switched bond graph corresponds to a so called hybrid system, i.e. a mixture of DAES and binary decisions.The thesis finally deals with an important computational issue, namely that of tuning a hybrid system to measurements. The approach presented is an extension of the tree induction principles developed within machine learning. The thesis is conduded by applying the presented modelling methodology on a siphon pump machine that was originally designed by Christoffer Polhem in 1697.
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- Strömberg, Jan-Erik, et al.
(författare)
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Bond Graph Supported Estimation of Discretely Changing Parameters
- 1993
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Ingår i: International Conference on Bond Graph Modeling, 1993. - 9781565550193 - 1565550196 ; , s. 47-52
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- A key factor in parameter estimation is the selection of model structure within which the fit to observed data is to be achieved. For linear systems, bond graphs have proven to give excellent support in this respect. However, for systems undergoing abrupt transitions between different (linear) modes of behaviour, the situation is far more complex. To handle this, we exploit the features of the ideal switching element as introduced by Strömberg, Top and Söderman. This solves the question of physical modelling as well as how to derive the supporting information. The approach is demonstrated on a non-trivial example using a multiple Kalman filter estimator.
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