| 1. |
- Astrom, K. J., et al.
(författare)
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Design of decoupled PI controller for two-by-two systems
- 2002
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Ingår i: IEE Proceedings - Control Theory & Applications. - IET. - 1350-2379. ; 149:1, s. 74-81
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Tidskriftsartikel (refereegranskat)abstract
- The design of PI controllers for systems with interacting loops is discussed. It is advantageous to deal with the interaction at the loop level, because supervisory control seldom has sufficient bandwidth. A new scheme based on modified scalar PI design and static decoupling is developed, in which the frequency characteristic of the coupling between the lower-level loops is taken into account. This leads to a design method emphasising the trade-off between the individual loop performances and the interaction indices introduced in the paper. The controller is easily implemented, due to its simple configuration based on standard components. A useful observation is that the interaction can be reduced substantially by using set-point weighting. The method is applied to three examples, including a model of a new laboratory system called the quadruple-tank process
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| 2. |
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| 3. |
- Johansson, Karl Henrik, et al.
(författare)
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Limit cycles with chattering in relay feedback systems
- 2002
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Ingår i: IEEE Transactions on Automatic Control. - IEEE. - 0018-9286. ; 47:9, s. 1414-1423
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Tidskriftsartikel (refereegranskat)abstract
- Relay feedback has a large variety of applications in control engineering. Several interesting phenomena occur in simple relay systems. In the paper, scalar linear systems with relay feedback are analyzed. It is shown that a limit cycle where part of the limit cycle consists of fast relay switchings can occur. This chattering is analyzed in detail and conditions for approximating it by a sliding mode are derived. A result on existence of limit cycles with chattering is given, and it is shown that the limit cycles can have arbitrarily many relay switchings each period. Limit cycles with regular sliding modes are also discussed. Examples illustrate the results.
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| 4. |
- Landgren, Matilda, et al.
(författare)
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An Automated System for the Detection and Diagnosis of Kidney Lesions in Children from Scintigraphy Images
- 2011
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Ingår i: Lecture Notes in Computer Science. - Springer Berlin / Heidelberg. - 1611-3349 (online) .- 0302-9743 (print). - 978-3-642-21226-0 (print) - 978-3-642-21227-7 (online) ; 6688, s. 489-500
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Konferensbidrag (refereegranskat)abstract
- Designing a system for computer aided diagnosis is a complex procedure requiring an understanding of the biology of the disease, insight into hospital workflow and awareness of available technical solutions. This paper aims to show that a valuable system can be designed for diagnosing kidney lesions in children and adolescents from 99m Tc-DMSA scintigraphy images. We present the chain of analysis and provide a discussion of its performance. On a per-lesion basis, the classification reached an ROC-curve area of 0.96 (sensitivity/specificity e.g. 97%/85%) measured using an independent test group consisting of 56 patients with 730 candidate lesions. We conclude that the presented system for diagnostic support has the potential of increasing the quality of care regarding this type of examination.
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| 5. |
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| 6. |
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| 7. |
- Ståhl, Daniel, et al.
(författare)
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Automatic Compartment Modelling and Segmentation for Dynamical Renal Scintigraphies
- 2011
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Ingår i: Lecture Notes in Computer Science. - Springer Berlin / Heidelberg. - 0302-9743 (print) .- 1611-3349 (online). - 978-3-642-21227-7 (online) - 978-3-642-21226-0 (print) ; 6688, s. 557-568
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Konferensbidrag (refereegranskat)abstract
- Time-resolved medical data has important applications in a large variety of medical applications. In this paper we study automatic analysis of dynamical renal scintigraphies. The traditional analysis pipeline for dynamical renal scintigraphies is to use manual or semiautomatic methods for segmentation of pixels into physical compartments, extract their corresponding time-activity curves and then compute the parameters that are relevant for medical assessment. In this paper we present a fully automatic system that incorporates spatial smoothing constraints, compartment modelling and positivity constraints to produce an interpretation of the full time-resolved data. The method has been tested on renal dynamical scintigraphies with promising results. It is shown that the method indeed produces more compact representations, while keeping the residual of fit low. The parameters of the time activity curve, such as peak-time and time for half activity from peak, are compared between the previous semiautomatic method and the method presented in this paper. It is also shown how to obtain new and clinically relevant features using our novel system.
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| 8. |
- Aanaes, H, et al.
(författare)
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Robust factorization
- 2002
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Ingår i: IEEE Transactions on Pattern Analysis and Machine Intelligence. - IEEE Computer Soc. - 0162-8828. ; 24:9, s. 1215-1225
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Tidskriftsartikel (refereegranskat)abstract
- Factorization algorithms for recovering structure and motion from an image stream have many advantages, but they usually require a set of well-tracked features. Such a set is in generally not available in practical applications. There is thus a need for making factorization algorithms deal effectively with errors in the tracked features. We propose a new and computationally efficient algorithm for applying an arbitrary errorfunction in the factorization scheme. This algorithm enables the use of robust statistical techniques and arbitrary noise models for the individual features. These techniques and models enable the factorization scheme to deal effectively with mismatched features, missing features, and noise on the individual features. The proposed approach further includes a new method for Euclidean reconstruction that significantly improves convergence of the factorization algorithms. The proposed algorithm has been implemented as a modification of the Christy-Horaud factorization scheme, which yields a perspective reconstruction. Based on this implementation, a considerable increase in error tolerance is demonstrated on real and synthetic data. The proposed scheme can, however, be applied to most other factorization algorithms.
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| 9. |
- Amani, Payam, et al.
(författare)
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Application of Control Theory to a Commercial Mobile Service Support System
- 2012
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Ingår i: International Journal On Advances in Telecommunications. - IARIA. - 1942-2601. ; 5:3&4
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Tidskriftsartikel (refereegranskat)abstract
- The Mobile Service Support system (MSS), which Ericsson AB develops, handles the setup of new subscribers and services into a mobile network. Experience from deployed systems show that traffic monitoring and control of the system will be crucial for handling overload situations that may occur at sudden traffic surges. In this paper we identify and explore some important control challenges for this type of systems. Further, we present analysis and experiments showing some advantages of proposed solutions. First, we develop a load-dependent server model for the system, which is validated in testbed experiments. Further, we propose a control design based on the model, and a method for estimation of response times and arrival rates. The main contribution of this paper is that we show how control theory methods and analysis can be used for commercial telecom systems. Parts of our results have been implemented in commercial products, validating the strength of our work.
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| 10. |
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Analysis for Science, Engineering and Beyond The Tribute Workshop in Honour of Gunnar Sparr held in Lund, May 8-9, 2008
- 2012
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Samlingsverk (redaktörskap) (övrigt vetenskapligt)abstract
- This book project was initiated at The Tribute Workshop in Honour of Gunnar Sparr and the follow-up workshop Inequalities, Interpolation, Non-commutative Analysis, Non-commutative Geometry and Applications, held at the Centre for Mathematical Sciences, Lund University in May and November of 2008. The resulting book is dedicated in celebration of Gunnar Sparr's sixty-fifth anniversary and more than forty years of exceptional service to mathematics and its applications in engineering and technology, mathematics and engineering education, as well as interdisciplinary, industrial and international cooperation. This book presents new advances in several areas of mathematics and engineering mathematics including applications in modern technology, engineering and life sciences. Thirteen high-quality chapters put forward many new methods and results, reviews of up to date research and open directions and problems for future research. A special chapter by Gunnar Sparr and Georg Lindgren contains a historical account and important aspects of engineering mathematics research and education, and the implementation of the highly successful education programme in Engineering Mathematics at Lund Institute of Technology, where not only the mathematical sciences have played a role. This book will serve as a source of inspiration for a broad spectrum of researchers and research students.
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