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Nils Damm Christophersen

Professor emeritus - Institutt for informatikk

E-post nilsch@ifi.uio.no

Brukernavn

Besøksadresse Gaustadalléen 23B Ole-Johan Dahls hus 0373 Oslo

Postadresse Postboks 1080 Blindern 0316 Oslo

Last ned visittkort

Faglige interesser

Min bakgrunn er innen anvendt matematikk og statistikk med vekt på signalbehandling. I tillegg er jeg opptatt av innovasjon og entreprenørskap i universitetssektoren.

Arbeidserfaring

2006 – 2009 Styremedlem UiO
2003 – 2004 Undervisningsdekan ved Matematisk-Naturvitenskapelig fakultet
2000 – 2006 Gruppeleder for forskningsgruppen innen Digital Signalbehandling og Bildeanalyse (DSB).
1998 – 1999 Leder Institutt for informatikk
1997 – 1998 Visiting scientist, Department of Statistics, Stanford University
1991 – Professor, Institutt for informatikk, UiO
1988 – 1989 Visiting scientist, Institute of Hydrology, UK
1986 – 1991 Professor II, Institutt for informatikk, UiO
1978 – 1991 Seniorforsker, Senter for Industriforskning/SINTEF, Oslo
1975 – 1977 Amanuensis, Fysisk Institutt, UiO
1972 – 1975 Forsker, Forsvarets Forskningsinstitutt

Utdannelse

1983 Dr. Philos. (matematisk modellering av miljøeffekter av sur nedbør), Senter for Industriforskning/SINTEF og Institutt for informatikk, UiO
1972 Cand. real. i kybernetikk, Forsvarets Forskningsinstitutt og Fysisk Institutt, UiO

Priser

Høyt sitert forsker (archives 2001 list) slik dette defineres av Institute for Scientific Information (ISI). Kom inn på denne listen på et tidspunkt da kun fem norske forskere var der.
UiOs innovasjonspris i 2016

Emneord: anvendt matematikk, statistikk, innovasjon, entreprenørskap

For en fullstendig publikasjonsliste, se CV

Dahl, Tobias Gulden; Pereira, SS; Christophersen, Nils Damm & Gesbert, David (2007). Intrinsic subspace convergence in TDD MIMO communication. IEEE Transactions on Signal Processing. ISSN 1053-587X. 55. doi: 10.1109/TSP.2007.896901. Fulltekst i vitenarkiv
Dahl, Tobias Gulden; Lingjærde, Ole Christian & Christophersen, Nils Damm (2005). Local-ICA: independent component analysis for sources with non-stationary amplitudes. I Bouzerdoum, A. & Beghdadi, A. (Red.), Proceedings of the Eighth International Symposium on Signal Processing and Its Applications, 2005. IEEE (Institute of Electrical and Electronics Engineers). ISSN 9780780392434. Fulltekst i vitenarkiv
Dahl, Tobias Gulden; Christophersen, Nils Damm & Gesbert, David (2004). Blind MIMO Transmission based on the Algebraic Power Method. IEEE Transactions on Signal Processing. ISSN 1053-587X. 52(9), s. 2424–2431. doi: 10.1109/TSP.2004.832000. Fulltekst i vitenarkiv
Dahl, T; Christophersen, Nils Damm & Gesbert, David (2004). Blind MIMO eigenmode transmission based on the algebraic power method. IEEE Transactions on Signal Processing. ISSN 1053-587X. 52, s. 2424–2431. Fulltekst i vitenarkiv
Bølviken, Erik; Acklam, Peter John; Christophersen, Nils Damm & Størdal, J.M. (2001). Monte-Carlo filters for non-linear state estimation. Automatica. ISSN 0005-1098. 37(2), s. 177–183. Fulltekst i vitenarkiv
Lingjærde, Ole Christian & Christophersen, Nils Damm (2000). Shrinkage Structure of Partial Least Squares. Scandinavian Journal of Statistics. ISSN 0303-6898. 27(3), s. 459–473. Fulltekst i vitenarkiv
Kugiumtzis, Dimitris; Lingjærde, Ole Christian & Christophersen, Nils Damm (1998). Regularized Local Linear Prediction of Chaotic Time Series. Physica D : Non-linear phenomena. ISSN 0167-2789. 112(3-4), s. 344–360. Fulltekst i vitenarkiv
Sjøberg, Dag & Christophersen, Nils Damm (1996). Den menneskefiendtlige informasjonsteknologien og andre myter, Schola. Fulltekst i vitenarkiv
Andersen, Sjur; Christophersen, Nils Damm; Mulder, Jan; Seip, Hans Martin & Vogt, Rolf David (1990). Aluminium solubility in the various soil horizons in an acidified catchment. I Mason, B.J. (Red.), The surface water acidification programme. Cambridge University Press. ISSN 9780521395335. s. 155–159. Fulltekst i vitenarkiv
Christophersen, Nils Damm; Hauhs, Michael; Mulder, Jan; Seip, Hans Martin & Vogt, Rolf David (1990). Hydrogeochemical processes in the Birkenes catchment. I Mason, B.J. (Red.), The surface water acidification programme. Cambridge University Press. ISSN 9780521395335. s. 97–106. Fulltekst i vitenarkiv
Christophersen, Nils Damm; Neal, Colin; Hooper, Richard; Vogt, Rolf David & Andersen, Sjur (1990). Christophersen N, Neal C, Hooper RP, Vogt RD, Andersen S. Modelling streamwater chemistry as a mixture of soilwater end-members — A step towards second-generation acidification models. Journal of Hydrology. ISSN 0022-1694. 116(1), s. 307–320. doi: 10.1016/0022-1694(90)90130-P. Fulltekst i vitenarkiv
Vogt, Rolf David; Andersen, Dag Olav; Andersen, Sjur; Christophersen, Nils Damm & Mulder, Jan (1990). Streamwater, soil-water chemistry, and water flow paths at Birkenes during a dry-wet hydrological cycle. I Mason, B.J. (Red.), The surface water acidification programme. Cambridge University Press. ISSN 9780521395335. s. 149–154. Fulltekst i vitenarkiv

Se alle arbeider i NVA

Leister, Wolfgang & Christophersen, Nils Damm (2014). INF5780 - Open source, open collaboration and innovation - Høst 2014. Fulltekst i vitenarkiv
Christophersen, Nils Damm & Leister, Wolfgang (2014). Governance of Open Source and Commons-Based Peer Production. Fulltekst i vitenarkiv
Leister, Wolfgang & Christophersen, Nils Damm (2013). INF5780 - Open source, open collaboration and innovation - Høst 2013. Fulltekst i vitenarkiv
Leister, Wolfgang & Christophersen, Nils Damm (2012). ITLED4240 - Åpen programvare, åpent samarbeid og innovasjon. Fulltekst i vitenarkiv
Leister, Wolfgang & Christophersen, Nils Damm (2012). INF5780 - Open source, open collaboration and innovation - Høst 2012. Fulltekst i vitenarkiv
Leister, Wolfgang & Christophersen, Nils Damm (2011). INF5780 - Open source, open collaboration and innovation - Høst 2011. Fulltekst i vitenarkiv Vis sammendrag
Free and open source software philosophy, practices, lisences, and business models; open publishing, open science, and creative commons; open hardware; commons-based peer production and peer-to-peer, open and disruptive innovation. The students shall attain a thorough theoretical as well as practical understanding of the various models of open and innovative collaboration on the Internet including the role of legal issues.
Leister, Wolfgang & Christophersen, Nils Damm (2011). Åpen programvare og åpent samarbeid. Fulltekst i vitenarkiv
Leister, Wolfgang; Christophersen, Nils Damm & Jayaraman, Karthik (2010). INF5780 - Open source, open collaboration and innovation - Høst 2010. Fulltekst i vitenarkiv
Christophersen, Nils Damm (2010). Wikipedia som dugnadsbasert allmenning. Fulltekst i vitenarkiv
Christophersen, Nils Damm (2009). Wikipedia and science – two knowledge commons. Fulltekst i vitenarkiv
Christophersen, Nils Damm (2009). Åpen kildekode, åpent samarbeid og innovasjon. Fulltekst i vitenarkiv
Leister, Wolfgang; Christophersen, Nils Damm & Tsiavos, Prodromos (2009). INF5780 - Open source, open collaboration and innovation - Høst 2009. Fulltekst i vitenarkiv
Christophersen, Nils Damm (2008). Fri programvare og andre dugnadsprosjekter i I- og U-land. Fulltekst i vitenarkiv
Christophersen, Nils Damm (2008). Open source, open collaboration, and disruptive innovation. Fulltekst i vitenarkiv
Christophersen, Nils Damm (2008). Lessons learned from the open source HISP health information program. Fulltekst i vitenarkiv
Christophersen, Nils Damm (2007). Wikipedia og andre nettsamfunn som inspirasjon for fremtidig formidling. Fulltekst i vitenarkiv
Dahl, Tobias Gulden; Lingjærde, Ole Christian; Christophersen, Nils Damm & Ekman, Torbjørn (2005). Local-ICA: independent component analysis for sources with non-stationary amplitudes. Fulltekst i vitenarkiv
Gesbert, David; Ekman, Torbjørn & Christophersen, Nils Damm (2002). Capacity limits of dense palm-sized MIMO arrays. Fulltekst i vitenarkiv
Dahl, Tobias; Christophersen, Nils Damm & Gesbert, David (2002). BIMA Blind MIMO Algorithm. Fulltekst i vitenarkiv
Christophersen, Nils Damm & Trulsen, Jan (2002). Få realfag inn i ex.phil. Aftenposten (morgenutg. : trykt utg.). ISSN 0804-3116. Fulltekst i vitenarkiv
Christophersen, Nils Damm (2002). Digital Dignalbehandling og Bildeanalyse(DSB) ved UiO. NORSIGnalet : organ for NORSIG, Norsk forening for signalbehandling. ISSN 0804-5623. s. 3–4. Fulltekst i vitenarkiv
Gesbert, David & Christophersen, Nils Damm (2002). Space: the final (wireless) fontier. NORSIGnalet : organ for NORSIG, Norsk forening for signalbehandling. ISSN 0804-5623. s. 4–8. Fulltekst i vitenarkiv
Dahl, Tobias; Christophersen, Nils Damm & Gesbert, David (2002). Identification of parallel MIMO channels in wireless communication using power iterations. Fulltekst i vitenarkiv
Holm, Sverre & Christophersen, Nils Damm (2001). Hvordan virker mobiltelefonen og hva har vi i vente? Fulltekst i vitenarkiv
Holm, Sverre & Christophersen, Nils Damm (2001). Hvordan virker mobiltelefonen og hva har vi i vente? Fulltekst i vitenarkiv
Leister, Wolfgang; Holm, Sverre & Christophersen, Nils Damm (2001). Multimedia Koding og Transmisjon - INF MKT Høst 2001. Fulltekst i vitenarkiv
Norum, Kaare Reidar; Christophersen, Nils Damm; Elverhøi, Anders; Grue, John & Uggerud, Einar (2000). Hånd i hånd med næringslivet. Dagens næringsliv. ISSN 0803-9372. Fulltekst i vitenarkiv
Lillekjendlie, Bjørn; Kugiumtzis, Dimitris & Christophersen, Nils Damm (1994). Chaotic time series : Part II: System identification and prediction. MIC Journal: Modeling, Identification and Control. ISSN 0332-7353. doi: 10.4173/mic.1994.4.2. Fulltekst i vitenarkiv Vis sammendrag
This paper is the second in a series of two, and describes the current state of the art in modelling and prediction of chaotic time series. Sampled data from deterministic non-linear systems may look stochastic when analysed with linear methods. However, the deterministic structure may be uncovered and non-linear models constructed that allow improved prediction. We give the background for such methods from a geometrical point of view, and briefly describe the following types of methods: global polynomials, local polynomials, multi layer perceptrons and semi-local methods including radial basis functions. Some illustrative examples from known chaotic systems are presented, emphasising the increase in prediction error with time. We compare some of the algorithms with respect to prediction accuracy and storage requirements, and list applications of these methods to real data from widely different areas.
Kugiumtzis, Dimitris; Lillekjendlie, Bjørn & Christophersen, Nils Damm (1994). Chaotic time series : Part 1: estimation of some invariant properties in state space. MIC Journal: Modeling, Identification and Control. ISSN 0332-7353. doi: 10.4173/mic.1994.4.1. Fulltekst i vitenarkiv Vis sammendrag
Certain deterministic non-linear systems may show chaotic behaviour. Time series derived from such systems seem stochastic when analyzed with linear techniques. However, uncovering the deterministic structure is important because it allows constructing more realistic and better models and thus improved predictive capabilities. This paper provides a review of two main key features of chaotic systems, the dimensions of their strange attractors and the Lyapunov exponents. The emphasis is on state space reconstruction techniques that are used to estimate these properties, given scalar observations. Data generated from equations known to display chaotic behaviour are used for illustration. A compilation of applications to real data fromwidely different fields is given. If chaos is found to be present, one may proceed to build non-linear models, which is the topic of the second paper in this series.
Christophersen, Nils & Bruaset, Are (1992). In 104: Naturvitenskapelig Programmeringslaboratorium. Fulltekst i vitenarkiv
Leister, Wolfgang; Christophersen, Nils Damm; Groven, Arne-Kristian; Tsiavos, Prodromos; Heggestøyl, Simen & Rødskog, Daniel (2015). INF5780 Compendium Autumn 2015: Open Source, Open Collaboration and Innovation. Norsk Regnesentral. Fulltekst i vitenarkiv Vis sammendrag
This document is the compendium for the course INF5780: Open source, open collaboration and innovation at the Department of Informatics, University of Oslo, written for the autumn semester of 2015. This multi-disciplinary compendium presents aspects of commons-based peer production, free and open source software, open licenses, open standards, and how to extract value from these phenomena in open innovation and business models.
Leister, Wolfgang; Christophersen, Nils Damm; Tsiavos, Prodromos; Groven, Arne-Kristian; Heggestøyl, Simen & Rødskog, Daniel [Vis alle 10 forfattere av denne artikkelen] (2014). INF5780 Compendium Autumn 2014: Open Source, Open Collaboration and Innovation. Norsk Regnesentral. Fulltekst i vitenarkiv Vis sammendrag
This document is the compendium for the course INF 5780: Open source, open collaboration and innovation at the Department of Informatics, University of Oslo, written for the autumn semester of 2014. This multi-disciplinary compendium presents aspects of commons-based peer production, free and open source software, open licenses, open standards, and how to extract value from these phenomena in open innovation and business models.
Leister, Wolfgang; Christophersen, Nils Damm; Tsiavos, Prodromos; Groven, Arne-Kristian; Heggestøyl, Simen & Rødskog, Daniel [Vis alle 10 forfattere av denne artikkelen] (2013). INF5780 Compendium Autumn 2013: Open Source, Open Collaboration and Innovation. Norsk Regnesentral. Fulltekst i vitenarkiv Vis sammendrag
This document is the compendium for the course INF 5780: Open source, open collaboration and innovation at the Department of Informatics, University of Oslo, written for the autumn semester of 2013. This multi-disciplinary compendium presents aspects of commons-based peer production, free and open source software, open licenses, open standards, and how to extract value from these phenomena in open innovation and business models.
Leister, Wolfgang & Christophersen, Nils Damm (2012). INF5780 Compendium Autumn 2012: Open Source, Open Collaboration and Innovation. Norsk Regnesentral. Fulltekst i vitenarkiv
Leister, Wolfgang; Christophersen, Nils Damm & Groven, Arne-Kristian (2012). ITLED 4240 Compendium Spring 2012: Open Source, Open Collaboration and Innovation. Norsk Regnesentral. Fulltekst i vitenarkiv Vis sammendrag
This document is the compendium for the course ITLED 4240: Open source, open collaboration and innovation at the Department of Informatics, University of Oslo, written for the spring semester of 2012. This multi-disciplinary compendium presents aspects of commons-based peer production, free and open source software, open licenses, open standards, and how to extract value from these phenomena in open innovation and business models.
Leister, Wolfgang & Christophersen, Nils Damm (2011). INF5780 Compendium Autumn 2011: Open source, Open collaboration and Innovation. Norsk Regnesentral. Fulltekst i vitenarkiv
Bølviken, Erik; Christophersen, Nils Damm & Storvik, Geir Olve (1998). Linear dynamical models, Kalman filtering and statistics. Lecture notes to IN-ST 259. Fulltekst i vitenarkiv
Bølviken, Erik Helmer; Acklam, Peter J.; Christophersen, Nils Damm & Størdal, John-Mikal (1997). Monte Carlo filters for non-linear state estimation. Universitetet i Oslo. Fulltekst i vitenarkiv
Kugiumtzis, Dimitris & Christophersen, Nils Damm (1997). State space reconstruction : method of delays vs singular spectrum approach. Universitetet i Oslo. Fulltekst i vitenarkiv Vis sammendrag
The analysis of chaotic time series requires proper reconstruction of the state space from the available data in order to successfully estimate invariant properties of the embedded attractor. Using the correlation dimension, we discuss the applicability of the two most common methods of reconstruction, the method of delays (MOD) and the Singular Spectrum Approach (SSA). Contrary to previous discussions, we found that the two methods perform equivalently in practice for noise-free data provided the parameters of the two methods are properly related. In fact, the quality of the reconstruction is in both cases determined by the choice of the time window length w and is independent of the selectedmethod. However, when the data are noisy, we find that SSA outperforms MOD.

Se alle arbeider i NVA

Publisert 4. nov. 2010 13:49 - Sist endret 11. nov. 2024 15:02