| 1. |
- Kanai, M, et al.
(författare)
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- 2023
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swepub:Mat__t
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| 2. |
- Niemi, MEK, et al.
(författare)
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- 2021
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swepub:Mat__t
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| 3. |
- Abazov, V. M., et al.
(författare)
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The upgraded DO detector
- 2006
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Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576. ; 565:2, s. 463-537
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Tidskriftsartikel (refereegranskat)abstract
- The DO experiment enjoyed a very successful data-collection run at the Fermilab Tevatron collider between 1992 and 1996. Since then, the detector has been upgraded to take advantage of improvements to the Tevatron and to enhance its physics capabilities. We describe the new elements of the detector, including the silicon microstrip tracker, central fiber tracker, solenoidal magnet, preshower detectors, forward muon detector, and forward proton detector. The uranium/liquid -argon calorimeters and central muon detector, remaining from Run 1, are discussed briefly. We also present the associated electronics, triggering, and data acquisition systems, along with the design and implementation of software specific to DO.
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| 4. |
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| 5. |
- Agüero, Juan C., et al.
(författare)
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Accuracy of linear multiple-input multiple-output (MIMO) models obtained by maximum likelihood estimation
- 2012
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Ingår i: Automatica. - : Elsevier BV. - 0005-1098 .- 1873-2836. ; 48:4, s. 632-637
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, we study the accuracy of linear multiple-input multiple-output (MIMO) models obtained by maximum likelihood estimation. We present a frequency-domain representation for the information matrix for general linear MIMO models. We show that the variance of estimated parametric models for linear MIMO systems satisfies a fundamental integral trade-off. This trade-off is expressed as a multivariable 'water-bed' effect. An extension to spectral estimation is also discussed.
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| 6. |
- Agüero, Juan C., et al.
(författare)
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Fundamental Limitations on the Accuracy of MIMO Linear Models Obtained by PEM for Systems Operating in Open Loop
- 2009
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Ingår i: Proceedings of the Joint 48th IEEE Conference on Decision and Control (CDC’09) and 28th Chinese Control Conference (CCC’09). - 9781424438716 ; , s. 482-487
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Konferensbidrag (refereegranskat)abstract
- In this paper we show that the variance of estimated parametric models for open loopMultiple-Input Multiple-Output (MIMO) systems obtained by the prediction error method (PEM) satisfies a fundamental integral limitation. The fundamental limitation gives rise to a multivariable 'water-bed' effect.
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| 7. |
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| 8. |
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| 9. |
- Cassasco, Diego S., et al.
(författare)
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On the Accuracy of Parameter Estimation for Continuous Time Nonlinear Systems from Sampled Data
- 2011
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Ingår i: Proceedings of the 50th IEEE Conference on Decision and Control. - 9781612847993 - 9781612848006 ; , s. 4308-4311
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Konferensbidrag (refereegranskat)abstract
- This paper deals with the issue of estimating the parameters in a continuous-time nonlinear dynamical model from sampled data. We focus on the issue of bias-variance trade-offs. In particular, we show that the bias error can be significantly reduced by using a particular form of sampled data model based on truncated Taylor series. This model retains the conceptual simplicity of models based on Euler integration but has much improved accuracy as a function of the sampled period.
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| 10. |
- Davies, Neil, et al.
(författare)
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The founding charter of the Genomic Observatories Network
- 2014
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Ingår i: GigaScience. - 2047-217X. ; 3:2
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Tidskriftsartikel (refereegranskat)abstract
- Abstract The co-authors of this paper hereby state their intention to work together to launch the Genomic Observatories Network (GOs Network) for which this document will serve as its Founding Charter. We define a Genomic Observatory as an ecosystem and/or site subject to long-term scientific research, including (but not limited to) the sustained study of genomic biodiversity from single-celled microbes to multicellular organisms.An international group of 64 scientists first published the call for a global network of Genomic Observatories in January 2012. The vision for such a network was expanded in a subsequent paper and developed over a series of meetings in Bremen (Germany), Shenzhen (China), Moorea (French Polynesia), Oxford (UK), Pacific Grove (California, USA), Washington (DC, USA), and London (UK). While this community-building process continues, here we express our mutual intent to establish the GOs Network formally, and to describe our shared vision for its future. The views expressed here are ours alone as individual scientists, and do not necessarily represent those of the institutions with which we are affiliated.
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| 11. |
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| 12. |
- Goodwin, Graham C., et al.
(författare)
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Robust Identification of Process Models from Plant Data
- 2008
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Ingår i: Journal of Process Control. - : Elsevier. - 0959-1524. ; 18:9, s. 810-820
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Tidskriftsartikel (refereegranskat)abstract
- A precursor to any advanced control solution is the step of obtaining an accurate model of the process. Suitable models can be obtained from phenomenological reasoning, analysis of plant data or a combination of both. Here, we will focus on the problem of estimating (or calibrating) models from plant data. A key goal is to achieve robust identification. By robust we mean that small errors in the hypotheses should lead to small errors in the estimated models. We argue that, in some circumstances, it is essential that special precautions, including discarding some part of the data, be taken to ensure that robustness is preserved. We present several practical case studies to illustrate the results.
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| 13. |
- Rojas, Cristian R., et al.
(författare)
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On the Equivalence of Least Costly and Traditional Experiment Design for Control
- 2008
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Ingår i: Automatica. - : Elsevier BV. - 0005-1098 .- 1873-2836. ; 44:11, s. 2706-2715
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Tidskriftsartikel (refereegranskat)abstract
- In this paper we establish the equivalence between least costly and traditional experiment design for control. We consider experiment design problems for both open and closed loop systems. In open loop, equivalence is established for three specific cases, relating to different parametrisations of the covariance expression (i.e. finite and high order approximations) and model structure (i.e. dependent and independently parameterised plant and noise models). In the closed loop setting, we consider only finite order covariance expressions. H(infinity) performance specifications for control are used to determine the bounds on the covariance expression for both the open and closed loop cases.
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| 14. |
- Rojas, Cristian R., 1980-, et al.
(författare)
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Robustness in Experiment Design
- 2012
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Ingår i: IEEE Transactions on Automatic Control. - 0018-9286 .- 1558-2523. ; 57:4, s. 860-874
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Tidskriftsartikel (refereegranskat)abstract
- This paper focuses on the problem of robust experiment design, i.e., how to design an input signal which gives relatively good estimation performance over a large number of systems and model structures. Specifically, we formulate the robust experiment design problem utilizing fundamental limitations on the variance of estimated parametric models as constraints. Using this formulation we design an input signal for situations where only diffuse a priori information is known about the system. Furthermore, we present a robust version of the unprejudiced optimal input design problem. To achieve this, we first develop a closed form solution for the input spectrum which minimizes the maximum weighted integral of the variance of the frequency response estimate over all model structures.
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| 15. |
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| 16. |
- Bentley, Michael J., et al.
(författare)
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A community-based geological reconstruction of Antarctic Ice Sheet deglaciation since the Last Glacial Maximum
- 2014
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Ingår i: Quaternary Science Reviews. - : Elsevier BV. - 0277-3791 .- 1873-457X. ; 100, s. 1-9
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Tidskriftsartikel (refereegranskat)abstract
- A robust understanding of Antarctic Ice Sheet deglacial history since the Last Glacial Maximum is important in order to constrain ice sheet and glacial-isostatic adjustment models, and to explore the forcing mechanisms responsible for ice sheet retreat. Such understanding can be derived from a broad range of geological and glaciological datasets and recent decades have seen an upsurge in such data gathering around the continent and Sub-Antarctic islands. Here, we report a new synthesis of those datasets, based on an accompanying series of reviews of the geological data, organised by sector. We present a series of timeslice maps for 20 ka, 15 ka, 10 ka and 5 ka, including grounding line position and ice sheet thickness changes, along with a clear assessment of levels of confidence. The reconstruction shows that the Antarctic Ice sheet did not everywhere reach the continental shelf edge at its maximum, that initial retreat was asynchronous, and that the spatial pattern of deglaciation was highly variable, particularly on the inner shelf. The deglacial reconstruction is consistent with a moderate overall excess ice volume and with a relatively small Antarctic contribution to meltwater pulse la. We discuss key areas of uncertainty both around the continent and by time interval, and we highlight potential priorities for future work. The synthesis is intended to be a resource for the modelling and glacial geological community.
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| 17. |
- Brus, Linda, 1977-
(författare)
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Nonlinear Identification and Control with Solar Energy Applications
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Nonlinear systems occur in industrial processes, economical systems, biotechnology and in many other areas. The thesis treats methods for system identification and control of such nonlinear systems, and applies the proposed methods to a solar heating/cooling plant. Two applications, an anaerobic digestion process and a domestic solar heating system are first used to illustrate properties of an existing nonlinear recursive prediction error identification algorithm. In both cases, the accuracy of the obtained nonlinear black-box models are comparable to the results of application specific grey-box models. Next a convergence analysis is performed, where conditions for convergence are formulated. The results, together with the examples, indicate the need of a method for providing initial parameters for the nonlinear prediction error algorithm. Such a method is then suggested and shown to increase the usefulness of the prediction error algorithm, significantly decreasing the risk for convergence to suboptimal minimum points. Next, the thesis treats model based control of systems with input signal dependent time delays. The approach taken is to develop a controller for systems with constant time delays, and embed it by input signal dependent resampling; the resampling acting as an interface between the system and the controller. Finally a solar collector field for combined cooling and heating of office buildings is used to illustrate the system identification and control strategies discussed earlier in the thesis, the control objective being to control the solar collector output temperature. The system has nonlinear dynamic behavior and large flow dependent time delays. The simulated evaluation using measured disturbances confirm that the controller works as intended. A significant reduction of the impact of variations in solar radiation on the collector outlet temperature is achieved, though the limited control range of the system itself prevents full exploitation of the proposed feedforward control. The methods and results contribute to a better utilization of solar power.
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| 18. |
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| 19. |
- Chen, Tianshi, et al.
(författare)
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Kernel Selection in Linear System Identification : Part II: A Classical Perspective
- 2011
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Ingår i: Proceedings of the 50th IEEE Conference on Decision and Control. - 9781612847993 - 9781612848006 ; , s. 4326-4331
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Konferensbidrag (refereegranskat)abstract
- In this companion paper, the choice of kernels for estimating the impulse response of linear stable systems is considered from a classical, “frequentist”, point of view. The kernel determines the regularization matrix in a regularized least squares estimate of an FIR model. The quality is assessed from a mean square error (MSE) perspective, and measures and algorithms for optimizing the MSE are discussed. The ideas are tested on the same data bank as used in Part I of the companion papers. The resulting findings and conclusions in the two papers are very similar despite the different perspectives.
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| 20. |
- Goodwin, Graham C., et al.
(författare)
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Good, Bad and Optimal Experiments for Identification
- 2006
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Ingår i: Forever Ljung in System Identification - Workshop on the occasion of Lennart Ljung’s 60th birthday. - Lund, Sweden : Studentlitteratur. - 9144020511
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 21. |
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| 22. |
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| 23. |
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| 24. |
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| 25. |
- Mueller, Claus, et al.
(författare)
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Generation of amplitude constrained signals with a prescribed spectrum
- 2012
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Ingår i: Automatica. - : Elsevier. - 0005-1098 .- 1873-2836. ; 48:1, s. 153-158
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Tidskriftsartikel (refereegranskat)abstract
- In this paper a real-time method for generating signals of constrained amplitude and a given (arbitrary) spectrum is presented. This technique is based on the concatenation of sinusoidal signals of suitably chosen frequencies in order to obtain a signal with the desired sample autocovariance sequence as the number of samples tends to infinity. The effectiveness of the method is demonstrated theoretically and via simulations.
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| 26. |
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| 27. |
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| 28. |
- Rojas, Cristian R., 1980-, et al.
(författare)
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A Receding Horizon Algorithm to Generate Binary Signals with a Prescribed Autocovariance
- 2007
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Ingår i: 2007 AMERICAN CONTROL CONFERENCE, VOLS 1-13. - 9781424409884 ; , s. 122-127
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Konferensbidrag (refereegranskat)abstract
- Optimal test signals are frequently specified in terms of their second order properties, e.g. autocovariance or spectrum. However, to utilize these signals in practice, one needs to be able to produce realizations whose second order properties closely approximate the prescribed properties. Of particular interest are binary waveforms since they have the highest form-factor in the sense that they achieve maximal energy for a given amplitude. In this paper we utilize ideas from model predictive control to generate a binary waveform whose sampled autocovariance is as close as possible to some prescribed autocovariance. Several simulated examples are presented verifying the veracity of the algorithm. Also, a proof of convergence is given for the special case of bandlimited white noise. This proof is based on expressing the system in the form of a switched linear system.
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| 29. |
- Rojas, Cristian R., et al.
(författare)
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Open-cut Mine Planning via Closed-loop Receding-horizon Optimal Control
- 2007
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Ingår i: Identification and Control. - London : Springer. - 9781846288982 ; , s. 43-62
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Bokkapitel (refereegranskat)abstract
- To obtain maximal return from a mining operation it is important that the sequence of mining steps be carefully planned. In this chapter we show how this problem can be converted into a closed-loop receding-horizon optimal control problem. Of particular interest is the formulation of the associated optimization problem in the face of uncertainty, e.g., future ore prices. We show how one can formulate “open-loop”, “reactive” and “closed-loop” policies to deal with price uncertainty. A “toy” example is presented to give insight into the problem. Also, a realistic mine-planning exercise is briefly described to highlight discrepancies between theory and practice.
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| 30. |
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| 31. |
- Rojas, Cristian R., et al.
(författare)
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Robust Optimal Experiment Design for System Identification
- 2007
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Ingår i: Automatica. - : Elsevier. - 0005-1098 .- 1873-2836. ; 43:6, s. 993-1008
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Tidskriftsartikel (refereegranskat)abstract
- This paper develops the idea of min-max robust experiment design for dynamic system identification. The idea of min-max experiment design has been explored in the statistics literature. However, the technique is virtually unknown by the engineering community and, accordingly, there has been little prior work on examining its properties when applied to dynamic system identification. This paper initiates an exploration of these ideas. The paper considers linear systems with energy (or power) bounded inputs. We assume that the parameters lie in a given compact set and optimise the worst case over this set. We also provide a detailed analysis of the solution for an illustrative one parameter example and propose a convex optimisation algorithm that can be applied more generally to a discretised approximation to the design problem. We also examine the role played by different design criteria and present a simulation example illustrating the merits of the proposed approach.
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| 32. |
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| 33. |
- Wittenmark, Björn, et al.
(författare)
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Adaptive Decoupling of Multivariable Systems
- 1987
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Ingår i: International Journal of Control. - : Informa UK Limited. - 0020-7179 .- 1366-5820. ; 46:6, s. 1992-2009
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Tidskriftsartikel (refereegranskat)abstract
- For many industrial processes, it is of interest to design a decoupling precompensator. The precompensator makes it possible to design controllers based on single-input-single-output models of the process. A model of the process must be known to design the precompensator. This paper shows how the precompensator can be designed adaptively using input-output measurements. The precompensator is first designed for the case when the process is known. The adaptive precompensator is then constructed using the certainty equivalence principle. The convergence properties and the implementation of the adaptive decoupler are discussed. It is shown that the adaptive scheme will converge provided the system is persistently excited and that a suitable model structure is used in the estimation.
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