| 1. |
- Rieth, M., et al.
(författare)
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A brief summary of the progress on the EFDA tungsten materials program
- 2013
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Ingår i: Journal of Nuclear Materials. - : Elsevier BV. - 0022-3115 .- 1873-4820. ; 442:1-3, s. S173-S180
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Tidskriftsartikel (refereegranskat)abstract
- The long-term objective of the European Fusion Development Agreement (EFDA) fusion materials programme is to develop structural and armor materials in combination with the necessary production and fabrication technologies for reactor concepts beyond the International Thermonuclear Experimental Reactor. The programmatic roadmap is structured into four engineering research lines which comprise fabrication process development, structural material development, armor material optimization, and irradiation performance testing, which are complemented by a fundamental research programme on "Materials Science and Modeling." This paper presents the current research status of the EFDA experimental and testing investigations, and gives a detailed overview of the latest results on materials research, fabrication, joining, high heat flux testing, plasticity studies, modeling, and validation experiments.
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| 2. |
- Rieth, M., et al.
(författare)
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Review on the EFDA programme on tungsten materials technology and science
- 2011
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Ingår i: Journal of Nuclear Materials. - : Elsevier BV. - 0022-3115 .- 1873-4820. ; 417:1-3, s. 463-467
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Tidskriftsartikel (refereegranskat)abstract
- All the recent DEMO design studies for helium cooled divertors utilize tungsten materials and alloys, mainly due to their high temperature strength, good thermal conductivity, low erosion, and comparably low activation under neutron irradiation. The long-term objective of the EFDA fusion materials programme is to develop structural as well as armor materials in combination with the necessary production and fabrication technologies for future divertor concepts. The programmatic roadmap is structured into four engineering research lines which comprise fabrication process development, structural material development, armor material optimization, and irradiation performance testing, which are complemented by a fundamental research programme on "Materials Science and Modeling". This paper presents the current research status of the EFDA experimental and testing investigations, and gives a detailed overview of the latest results on fabrication, joining, high heat flux testing, plasticity, modeling, and validation experiments.
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| 3. |
- Andersson, Olov, 1979-, et al.
(författare)
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WARA-PS : a research arena for public safety demonstrations and autonomous collaborative rescue robotics experimentation
- 2021
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Ingår i: Autonomous Intelligent Systems. - : Springer Nature. - 2730-616X. ; 1:1
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Tidskriftsartikel (refereegranskat)abstract
- A research arena (WARA-PS) for sensing, data fusion, user interaction, planning and control of collaborative autonomous aerial and surface vehicles in public safety applications is presented. The objective is to demonstrate scientific discoveries and to generate new directions for future research on autonomous systems for societal challenges. The enabler is a computational infrastructure with a core system architecture for industrial and academic collaboration. This includes a control and command system together with a framework for planning and executing tasks for unmanned surface vehicles and aerial vehicles. The motivating application for the demonstration is marine search and rescue operations. A state-of-art delegation framework for the mission planning together with three specific applications is also presented. The first one concerns model predictive control for cooperative rendezvous of autonomous unmanned aerial and surface vehicles. The second project is about learning to make safe real-time decisions under uncertainty for autonomous vehicles, and the third one is on robust terrain-aided navigation through sensor fusion and virtual reality tele-operation to support a GPS-free positioning system in marine environments. The research results have been experimentally evaluated and demonstrated to industry and public sector audiences at a marine test facility. It would be most difficult to do experiments on this large scale without the WARA-PS research arena. Furthermore, these demonstrator activities have resulted in effective research dissemination with high public visibility, business impact and new research collaborations between academia and industry.
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| 4. |
- Heuberger, Peter S. C., et al.
(författare)
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Orthonormal basis functions in time and frequency domain : Hambo transform theory
- 2004
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Ingår i: SIAM Journal of Control and Optimization. - 0363-0129 .- 1095-7138. ; 42:4, s. 1347-1373
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Tidskriftsartikel (refereegranskat)abstract
- The class of finite impulse response (FIR), Laguerre, and Kautz functions can be generalized to a family of rational orthonormal basis functions for the Hardy space H2 of stable linear dynamical systems. These basis functions are useful for constructing efficient parameterizations and coding of linear systems and signals, as required in, e.g., system identification, system approximation, and adaptive filtering. In this paper, the basis functions are derived from a transfer function perspective as well as in a state space setting. It is shown how this approach leads to alternative series expansions of systems and signals in time and frequency domain. The generalized basis functions induce signal and system transforms (Hambo transforms), which have proved to be useful analysis tools in various modelling problems. These transforms are analyzed in detail in this paper, and a large number of their properties are derived. Principally, it is shown how minimal state space realizations of the system transform can be obtained from minimal state space realizations of the original system and vice versa.
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| 5. |
- Rönnberg, Sarah K., et al.
(författare)
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Harmonic emission before and after changing to LED and CFL - Part I: Laboratory measurements for a domestic customer
- 2010
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Ingår i: 14th International Conference on Harmonics and Quality of Power (ICHQP). - Piscataway, NJ : IEEE Communications Society. - 9781424472444 - 9781424472451
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Konferensbidrag (refereegranskat)abstract
- This paper presents an investigation after the impact on a number of power-quality parameters due to the change from incandescent lamps to energy saving lamps like CFL and LED. The measurements were conducted in a full-scale laboratory model with ordinary household equipment connected, thus simulating an ordinary domestic customer. Incandescent lamps have been replaced in stages by CFL and LED lamps. The CFL's and LED lamps will contribute to an increase in current distortion but the amplitude of the harmonics is quite low so the change of lighting will only have a minor effect on the total current harmonic distortion. It is also shown that the (total) power factor is not a good indicator to compare the impact of different loads on the system.
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| 6. |
- Rönnberg, Sarah Karolina, et al.
(författare)
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Interaction between narrowband power-line communication and end-user equipment
- 2011
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Ingår i: IEEE Transactions on Power Delivery. - 0885-8977 .- 1937-4208. ; 26:3, s. 2034-2039
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Tidskriftsartikel (refereegranskat)abstract
- This paper discusses some of the electromagnetic-compatibility issues concerning the use of power lines for communication. Based on a series of measurements performed in a laboratory environment and in the field, five different types of interactions between communication and end-user equipment are distinguished. Measurement examples are shown for several of these types. It is concluded that the creation of a low-impedance path by end-user equipment is the main cause of interference.
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| 7. |
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| 8. |
- Wahlberg, Bo, et al.
(författare)
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Identification of wiener systems with process noise is a nonlinear errors-in-variables problem
- 2014
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Ingår i: Proceedings of the IEEE Conference on Decision and Control. - : IEEE conference proceedings. ; , s. 3328-3333
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Konferensbidrag (refereegranskat)abstract
- This paper considers the identification of stochastic Wiener dynamic systems, that is linear dynamic systems with process noise, where the measurable output signal is a nonlinear function of the output from the linear system corrupted with additive measurement noise. It is shown how stochastic Wiener system identification can be viewed as a particular non-linear model errors-in-variables problem, for which there exists a large literature. We compare the maximum likelihood method with prediction error minimization methods based on the conditional mean predictor for Wiener systems. Related methods have previously been studied in the framework of identification of non-linear error-in-variables models. We extend these results by taking the input signal to the Wiener system into consideration. For example, the input will affect the variance of the prediction errors. Hence, a prediction error method with a variance weighting is derived to obtain more reliable parameter estimates. An advantage with the prediction error method is that for certain special cases we can avoid numerical integration. We also discuss how the unscented transform can be used to obtain an approximate predictor for the prediction error method. The numerical evaluation of these methods is performed on a simple first order FIR system with a cubic nonlinearity, for which some illustrative analytic properties are derived.
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| 9. |
- Ha, H., et al.
(författare)
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Reweighted nuclear norm regularization : A SPARSEVA approach
- 2015
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Ingår i: IFAC-PapersOnLine. - : Elsevier. - 2405-8963. ; 48:28, s. 1172-1177
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this paper is to develop a method to estimate high order FIR and ARX models using least squares with re-weighted nuclear norm regularization. Typically, the choice of the tuning parameter in the reweighting scheme is computationally expensive, hence we propose the use of the SPARSEVA (SPARSe Estimation based on a VAlidation criterion) framework to overcome this problem. Furthermore, we suggest the use of the prediction error criterion (PEC) to select the tuning parameter in the SPARSEVA algorithm. Numerical examples demonstrate the veracity of this method which has close ties with the traditional technique of cross validation, but using much less computations.
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| 10. |
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