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| 2. |
- Biteus, Jonas, 1977-, et al.
(författare)
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Determining the Fault Status of a Component and its Readiness, with a Distributed Automotive Application
- 2009
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Ingår i: Engineering applications of artificial intelligence. - : Elsevier BV. - 0952-1976 .- 1873-6769. ; 22:3, s. 363-373
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Tidskriftsartikel (refereegranskat)abstract
- In systems using only single-component tests, the fault status of a component is ready if a test only supervising the component has been evaluated. However, if plausibility tests that supervise multiple components are used, then a component can be ready before all tests supervising the component have been evaluated. Based on test results, this paper contributes with conditions on when a component is ready. The conditions on readiness are given for both centralized and distributed systems and are here applied to the distributed diagnostic system in an automotive vehicle.
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| 3. |
- Chiavari, C, et al.
(författare)
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Atmospheric corrosion of historical organ pipes: The influence of environment and materials
- 2008
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Ingår i: Corrosion Science. - : Elsevier BV. - 0010-938X. ; 50:9, s. 2444-2455
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Tidskriftsartikel (refereegranskat)abstract
- The corrosion of lead-rich pipes in historical organs in different parts of Europe has been investigated. The influence of the environment and the composition and microstructure of the pipe metal was studied. Pipe Corrosion was documented by visual inspection (boroscope). The corrosion attack and the composition and microstructure of the metal were characterized by OM, SEM, XRD, IC and FAAS. It is shown that the degree of corrosion of the pipes is correlated to the concentration of gaseous acetic and formic acid in the organ. The organic acids are emitted by the wood from which the wind system is built. It is also shown that pipe corrosion decreases with increasing tin content in the range 0-4% (wt). Possible conservation strategies are discussed. (c) 2008 Elsevier Ltd. All rights reserved.
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| 4. |
- Frisk, Erik, 1971-, et al.
(författare)
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A toolbox for design of diagnosis systems
- 2006
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Ingår i: IFAC Safeprocess06,2006. - Beijing, China : IFAC. ; , s. 703-
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Konferensbidrag (refereegranskat)abstract
- Design of diagnosis systems is a complex task that involves many different steps. Full understanding of all different parts of the design procedure requires deep knowledge on theory from a wide variety of subjects. Thus, to encourage the use of results from diagnosis research it is highly desirable to have software support in the design process. This paper describes ongoing work for determining an architecture for such a toolbox. The paper also describes software solutions in the toolbox. In industry as well as in universities, Matlab is probably the most widespread tool used by control engineers. Therefore the toolbox is primarily based upon Matlab but also some computer algebraic tools such as Mathematica and Maple are used.
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| 5. |
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| 6. |
- Frisk, Erik, et al.
(författare)
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Analysis and Design of Diagnosis Systems Based on the Structural Differential Index
- 2017
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Ingår i: 20th IFAC World Congress. - : ELSEVIER SCIENCE BV. ; , s. 12236-12242
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Konferensbidrag (refereegranskat)abstract
- Structural approaches have shown to be useful for analyzing and designing diagnosis systems for industrial systems. In simulation and estimation literature, related theories about differential index have been developed and, also there, structural methods have been successfully applied for simulating large-scale differential algebraic models. A main contribution of this paper is to connect those theories and thus making the tools from simulation and estimation literature available for model based diagnosis design. A key step in the unification is an extension of the notion of differential index of exactly determined systems of equations to overdetermined systems of equations. A second main contribution is how differential-index can be used in diagnosability analysis and also in the design stage where an exponentially sized search space is significantly reduced. This allows focusing on residual generators where basic design techniques, such as standard state-observation techniques and sequential residual generation are directly applicable. The developed theory has a direct industrial relevance, which is illustrated with discussions on an automotive engine example. (C) 2017, IFAC (International Federation of Automatic Control) Hosting by Elsevier Ltd. All rights reserved.
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| 7. |
- Frisk, Erik, et al.
(författare)
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Diagnosability Analysis Considering Causal Interpretations for Differential Constraints
- 2012
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Ingår i: IEEE transactions on systems, man and cybernetics. Part A. Systems and humans. - : Institute of Electrical and Electronics Engineers (IEEE). - 1083-4427 .- 1558-2426. ; 42:5, s. 1216-1229
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Tidskriftsartikel (refereegranskat)abstract
- This paper is focused on structural approaches to study diagnosability properties given a system model taking into account, both simultaneously or separately, integral and differential causal interpretations for differential constraints. We develop a model characterization and corresponding algorithms, for studying system diagnosability using a structural decomposition that avoids generating the full set of system analytical redundancy relations. Simultaneous application of integral and differential causal interpretations for differential constraints results in a mixed causality interpretation for the system. The added power of mixed causality is demonstrated using a Reverse Osmosis Subsystem from the Advanced Water Recovery System developed at the NASA Johnson Space Center. Finally, we summarize our work and provide a discussion of the advantages of mixed causality over just derivative or just integral causality.
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| 8. |
- Frisk, Erik, 1971-, et al.
(författare)
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Lowering Orders of Derivatives in Non-linear Consistency Relations : Theory and Simulation Examples
- 2003
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Consistency relations are often used to design residual generators based on non-linear process models. A main difficulty is that they generally include time differentiated versions of known or measured signals which are difficult to estimate in a noisy environment, especially higher order derivatives. The main results of this paper show how to lower, or if possible avoid, the need to estimate derivatives of known signals in order to compute the residual. This is achieved by rewriting the problem into an integrability problem using state-space realization theory. An attractive feature of the approach is that general differential algebraic system descriptions can be handled in the same way as for example ordinary differential equations and also that stability of the residual generator is always guaranteed.
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| 9. |
- Frisk, Erik, 1971-, et al.
(författare)
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Lowering Orders of Derivatives in Non-linear Residual Generation using Realization Theory
- 2005
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Ingår i: Automatica. - : Elsevier BV. - 0005-1098 .- 1873-2836. ; 41:10, s. 1799-1807
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Tidskriftsartikel (refereegranskat)abstract
- Consistency relations are often used to design residual generators based on non-linear process models. A main difficulty is that they generally include time differentiated versions of known signals which are difficult to estimate in a noisy environment. The main results of this paper show how to lower the need to estimate derivatives of known signals in order to compute a residual. Necessary and sufficient conditions for lowering the order of the derivatives one step are presented and a main step in the approach is to obtain a state-space realization of the residual generator. An attractive feature of the approach is that general differential algebraic system descriptions can be handled in the same way as for example ordinary differential equations and also that stability of the residual generator is always guaranteed.
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| 10. |
- Frisk, Erik, et al.
(författare)
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Sensor placement for fault isolation in linear differential-algebraic systems
- 2009
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Ingår i: Automatica. - : Elsevier BV. - 0005-1098 .- 1873-2836. ; 45:2, s. 364-371
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Tidskriftsartikel (refereegranskat)abstract
- An algorithm is proposed for computing which sensor additions make a diagnosis requirement specification regarding fault detectability and isolability attainable for a given linear differential-algebraic model. Restrictions on possible sensor locations can be given, and if the diagnosis specification is not attainable with any available sensor addition, the algorithm provides the solutions that maximize specification fulfillment. Previous approaches with similar objectives have been based on the model structure only. Since the proposed algorithm utilizes the analytical expressions, it can handle models where structural approaches fail.
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