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| 2. |
- Biteus, Jonas, 1977-, et al.
(author)
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Determining the Fault Status of a Component and its Readiness, with a Distributed Automotive Application
- 2009
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In: Engineering applications of artificial intelligence. - : Elsevier BV. - 0952-1976 .- 1873-6769. ; 22:3, s. 363-373
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Journal article (peer-reviewed)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.
(author)
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Atmospheric corrosion of historical organ pipes: The influence of environment and materials
- 2008
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In: Corrosion Science. - : Elsevier BV. - 0010-938X. ; 50:9, s. 2444-2455
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Journal article (peer-reviewed)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.
(author)
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A toolbox for design of diagnosis systems
- 2006
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In: IFAC Safeprocess06,2006. - Beijing, China : IFAC. ; , s. 703-
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Conference paper (peer-reviewed)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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| 6. |
- Frisk, Erik, 1971-, et al.
(author)
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Lowering Orders of Derivatives in Non-linear Residual Generation using Realization Theory
- 2005
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In: Automatica. - : Elsevier BV. - 0005-1098 .- 1873-2836. ; 41:10, s. 1799-1807
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Journal article (peer-reviewed)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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| 7. |
- Frisk, Erik, et al.
(author)
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Sensor placement for fault isolation in linear differential-algebraic systems
- 2009
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In: Automatica. - : Elsevier BV. - 0005-1098 .- 1873-2836. ; 45:2, s. 364-371
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Journal article (peer-reviewed)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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| 8. |
- Gustafsson, Fredrik, et al.
(author)
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On Threshold Optimization in Fault Tolerant Systems
- 2008
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In: Proceedings of the 17th IFAC World Congress. ; , s. 7883-7888
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Conference paper (peer-reviewed)abstract
- Fault tolerant systems are considered, where a nominal system is monitored by a fault detection algorithm, and the nominal system is switched to a backup system in case of a detected fault. Conventional fault detection is in the classical setting a trade-off between detection probability and false alarm probability. For the considered fault tolerant system, a system failure occurs either when the nominal system gets a fault that is not detected, or when the fault detector signals an alarm and the backup system breaks down. This means that the trade-off for threshold setting is different and depends on the overall conditions, and the characterization and understanding of this trade-off is important. It is shown that the probability of system failure can be expressed in a general form based on the probability of false alarm and detection power, and based on this form the influence ratio is introduced. This ratio includes all information about the supervised system and the backup system that is needed for the threshold optimization problem. It is shown that the influence ratio has a geometrical interpretation as the gradient of the receiver operating characteristics (ROC) curve at the optimal point, and furthermore, it is the threshold for the optimal test quantity in important cases.
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| 9. |
- Gyllenhammar, Andreas, et al.
(author)
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Flodpärlmussla, Resultat från inventeringarna 1996-2005
- 2005
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Reports (other academic/artistic)abstract
- I denna rapport redovisas de insatser som gjorts för att kartlägga Jämtlands läns bestånd av flodpärlmussla (Margaritifera margaritifera). En kartläggning av historiska bestånd har gjorts, mestadels baserad på litteraturstudier. I rapporten redovisas resultaten från det inventeringsarbete som utförts av Länsstyrelsen i Jämtlands län åren 1996-2005. Resultaten presenteras i form av kartor, figurer och tabeller där beståndens geografiska lokalisering, storlek och reproduktionsstatus redovisas. Länet har idag 53 lokaler med bestånd av flodpärlmussla. I 30 stycken av dessa bestånd förekommer reproduktion men i över hälften (18st) är reproduktionen svag. 12 av bestånden har ett uppskattat individantal på över 10000 individer. Jämtland har i dagsläget Sveriges största bestånd av flodpärlmussla. I Storån, norr om Hammerdal, har antalet individer beräknats till 4,5 miljoner. En mer omfattande analys av läget för flodpärlmusslan i länet kommer att göras då inventeringsmaterialet datalagts i större omfattning och då ytterligare miljödata finns sammanställda. Slutsatserna pekar på vikten av att ytterligare miljödata tillgängliggörs för att möjliggöra en fördjupad analys av musselbeståndens och omgivningsparametrarnas status. Slutligen presenteras hur Länsstyrelsens arbete med flodpärlmussla kommer att fortskrida under 2006, med bl a utformning av ett miljöövervakningsprogram och planering av skyddsåtgärder.
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| 10. |
- Hellström, Erik, 1979-, et al.
(author)
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Design of a Well-behaved Algorithm for On-board Look-ahead Control
- 2008
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In: IFAC World Congress,2008.
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Conference paper (peer-reviewed)abstract
- A look-ahead controller is developed for a heavy diesel truck that utilizes information about the road topography ahead of the vehicle when the route is known. A dedicated prediction model is formulated where special attention is given to properly include gear shifting. The nature of the problem is analyzed for the purpose of optimization, and a well performing dynamic programming algorithm is tailored. A key step for satisfactory solutions with a sufficiently low computational effort is to avoid numerical problems. The focus here is the choice of discretization method, and it turns out that a basic analysis give decisive insight into the interplay between the criterion and the discretization errors. The resulting algorithm is demonstrated to perform well in real on-line tests on a highway.
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