Dr Bjorn Ruffer

Dr Bjorn Ruffer

Lecturer

School of Mathematical and Physical Sciences (Mathematics)

Career Summary

Biography

Dr Rüffer received the MSc (w/ distinction) in mathematics degree from
the University of Warwick, UK, in 2004, and the Dr. rer. nat. (PhD)
degree in mathematics from the University of Bremen, Germany, in 2007.

After a sequence of post-doctoral appointments at the University of
Newcastle (2007-2009), the University of Melbourne (2009-2011), and
the University of Paderborn (2011-2015), he re-joined the University
of Newcastle in 2015. He has held visiting positions at the Kyushu
Institute of Technology, Japan, the University of Passau, Germany, and
the University of British Columbia, Canada.

To the research community Dr Rüffer contributes as a referee for a
number of scientific journals and conferences, as an organiser of
scientific conferences, as associate editor for two flagship journals,
and as reviewer for a several research funding bodies. At
the University of Newcastle he has served as a member of the Academic
Senate and a member of the Faculty Board of the Faculty of Science
(both 2016-2017).

Qualifications

  • PhD, University of Bremen - Germany
  • Master of Science, University of Warwick - England

Keywords

  • Difference and functional equations
  • Optimisation
  • Ordinary differential equations
  • Systems theory and control

Fields of Research

Code Description Percentage
010109 Ordinary Differential Equations, Difference Equations and Dynamical Systems 70
010203 Calculus of Variations, Systems Theory and Control Theory 20
010204 Dynamical Systems in Applications 10

Professional Experience

Academic appointment

Dates Title Organisation / Department
1/4/2014 - 1/9/2014 Visiting Professor University of Passau
Faculty of Computer Science and Mathematics
Germany
28/4/2018 - 28/6/2018 Visiting Professor University of British Columbia
Canada

Membership

Dates Title Organisation / Department
1/1/2008 -  Senior Member, IEEE Institute of Electrical and Electronics Engineers
United States
1/1/2010 -  Associate Editor Systems & Control Letters
Netherlands
15/5/2018 -  Associate Editor Automatica J. IFAC
Netherlands
1/1/2016 -  Member, SIAM Society for Industrial and Applied Mathematics (SIAM)
United States

Awards

Recognition

Year Award
2018 Outstanding reviewer for 2016-2017
Automatica J. IFAC

Research Award

Year Award
2012 Premium Award (best paper)
IET
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Publications

For publications that are currently unpublished or in-press, details are shown in italics.

Highlighted Publications

Year Citation Altmetrics Link
2007 Dashkovskiy S, Ruffer BS, Wirth FR, 'An ISS small gain theorem for general networks', Mathematics of Control, Signals, and Systems, 19 93-122 (2007)
DOI 10.1007/s00498-007-0014-8
Citations Scopus - 245Web of Science - 208
2010 Dashkovskiy SN, Ruffer BS, Wirth FR, 'Small gain theorems for large scale systems and construction of ISS Lyapunov functions', SIAM Journal on Control and Optimization, 48 4089-4118 (2010)
DOI 10.1137/090746483
Citations Scopus - 210Web of Science - 182
2010 Ruffer BS, Kellett CM, Weller SR, 'Connection between cooperative positive systems and integral input-to-state stability of large-scale systems', Automatica, 46 1019-1027 (2010) [C1]
DOI 10.1016/j.automatica.2010.03.012
Citations Scopus - 48Web of Science - 42
Co-authors Steven Weller, Chris Kellett
2013 Ruffer BS, Van De Wouw N, Mueller M, 'Convergent systems vs. incremental stability', Systems and Control Letters, 62 277-285 (2013) [C1]
DOI 10.1016/j.sysconle.2012.11.015
Citations Scopus - 46Web of Science - 43

Journal article (18 outputs)

Year Citation Altmetrics Link
2019 Giladi O, Rüffer BS, 'A Perron Frobenius type result for integer maps and applications', Positivity, 23 545-570 (2019) [C1]
DOI 10.1007/s11117-018-0624-z
Co-authors Ohad Giladi
2019 Guiver C, Logemann H, Rüffer B, 'Small-gain stability theorems for positive Lur e inclusions', Positivity, 23 249-289 (2019) [C1]
DOI 10.1007/s11117-018-0605-2
Citations Scopus - 1
2019 Tran DN, Ruffer BS, Kellett CM, 'Convergence Properties for Discrete-time Nonlinear Systems', IEEE Transactions on Automatic Control, 64 3415-3422 (2019) [C1]
DOI 10.1109/TAC.2018.2879951
Citations Scopus - 1
Co-authors Chris Kellett
2018 Noroozi N, Geiselhart R, Gruene L, Ruffer BS, Wirth FR, 'Nonconservative Discrete-Time ISS Small-Gain Conditions for Closed Sets', IEEE TRANSACTIONS ON AUTOMATIC CONTROL, 63 1231-1242 (2018) [C1]
DOI 10.1109/TAC.2017.2735194
Citations Scopus - 10Web of Science - 7
2018 Giladi O, Rüffer BS, 'A Lyapunov Function Construction for a Non-convex Douglas-Rachford Iteration', Journal of Optimization Theory and Applications, 180 729-750 (2018) [C1]
DOI 10.1007/s10957-018-1405-3
Co-authors Ohad Giladi
2015 Dirr G, Ito H, Rantzer A, Rueffer BS, 'SEPARABLE LYAPUNOV FUNCTIONS FOR MONOTONE SYSTEMS: CONSTRUCTIONS AND LIMITATIONS', DISCRETE AND CONTINUOUS DYNAMICAL SYSTEMS-SERIES B, 20 2497-2526 (2015) [C1]
DOI 10.3934/dcdsb.2015.20.2497
Citations Scopus - 39Web of Science - 28
2014 Rüffer BS, 'Input-to-state stability for discrete-time monotone systems', Proceedings of the 21st International Symposium on Mathematics Theory of Networks and Systems (MTNS), 96-102 (2014)
2013 Ruffer BS, Van De Wouw N, Mueller M, 'Convergent systems vs. incremental stability', Systems and Control Letters, 62 277-285 (2013) [C1]
DOI 10.1016/j.sysconle.2012.11.015
Citations Scopus - 46Web of Science - 43
2013 Ito H, Jiang Z-P, Dashkovskiy SN, Rüffer BS, 'Robust stability of networks of iISS systems: Construction of sum-type Lyapunov functions', IEEE Transactions on Automatic Control, 58 1192-1207 (2013) [C1]
DOI 10.1109/TAC.2012.2231552
Citations Scopus - 53Web of Science - 46
2011 Rüffer BS, Wirth FR, 'Stability verification for monotone systems using homotopy algorithms', Numerical Algorithms, 58 529-543 (2011) [C1]

A monotone self-mapping of the nonnegative orthant induces a monotone discrete-time dynamical system which evolves on the same orthant. If with respect to this system the origin i... [more]

A monotone self-mapping of the nonnegative orthant induces a monotone discrete-time dynamical system which evolves on the same orthant. If with respect to this system the origin is attractive then there must exist points whose image under the monotone map is strictly smaller than the original point, in the component-wise partial ordering. Here it is shown how such points can be found numerically, leading to a recipe to compute order intervals that are contained in the region of attraction and where the monotone map acts essentially as a contraction. An important application is the numerical verification of so-called generalized small-gain conditions that appear in the stability theory of large-scale systems. © 2011 Springer Science+Business Media, LLC.

DOI 10.1007/s11075-011-9468-3
Citations Scopus - 8Web of Science - 6
2010 Rüffer BS, Kellett CM, Dower PM, Weller SR, 'Belief propagation as a dynamical system: The linear case and open problems', IET Control Theory and Applications, 4 1188-1200 (2010) [C1]
DOI 10.1049/iet-cta.2009.0233
Citations Scopus - 10Web of Science - 9
Co-authors Chris Kellett, Steven Weller
2010 Ruffer BS, Sailer R, Wirth FR, 'Comments on "A Multichannel IOS Small Gain Theorem for Systems With Multiple Time-Varying Communication Delays', IEEE Transactions on Automatic Control, 55 1722-1725 (2010)
DOI 10.1109/tac.2010.2048938
Citations Scopus - 5Web of Science - 5
2010 Dashkovskiy SN, Ruffer BS, 'Local ISS of large-scale interconnections and estimates for stability regions', Systems and Control Letters, 59 241-247 (2010)
DOI 10.1016/j.sysconle.2010.02.001
Citations Scopus - 28Web of Science - 23
2010 Dashkovskiy SN, Ruffer BS, Wirth FR, 'Small gain theorems for large scale systems and construction of ISS Lyapunov functions', SIAM Journal on Control and Optimization, 48 4089-4118 (2010)
DOI 10.1137/090746483
Citations Scopus - 210Web of Science - 182
2010 Ruffer BS, Kellett CM, Weller SR, 'Connection between cooperative positive systems and integral input-to-state stability of large-scale systems', Automatica, 46 1019-1027 (2010) [C1]
DOI 10.1016/j.automatica.2010.03.012
Citations Scopus - 48Web of Science - 42
Co-authors Steven Weller, Chris Kellett
2010 Rüffer BS, 'Small-Gain Conditions and the Comparison Principle', IEEE TRANSACTIONS ON AUTOMATIC CONTROL, 55 1732-1736 (2010)
DOI 10.1109/TAC.2010.2048053
Citations Scopus - 21Web of Science - 19
2010 Ruffer BS, 'Monotone inequalities, dynamical systems, and paths in the positive orthant of Euclidean n-space', Positivity, 14 257-283 (2010) [C1]
DOI 10.1007/s11117-009-0016-5
Citations Scopus - 48Web of Science - 38
2007 Dashkovskiy S, Ruffer BS, Wirth FR, 'An ISS small gain theorem for general networks', Mathematics of Control, Signals, and Systems, 19 93-122 (2007)
DOI 10.1007/s00498-007-0014-8
Citations Scopus - 245Web of Science - 208
Show 15 more journal articles

Conference (1 outputs)

Year Citation Altmetrics Link
2019 Ito H, Rüffer BS, 'A Left Eigenvector Producing a Smooth Lyapunov Function of ISS Networks', Positive Systems. Theory and Applications (POSTA 2018). Lecture Notes in Control and Information Sciences, Hangzhou, China (2019) [E1]
DOI 10.1007/978-3-030-04327-8_20
Citations Scopus - 1
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Grants and Funding

Summary

Number of grants 1
Total funding $442,830

Click on a grant title below to expand the full details for that specific grant.

20161 grants / $442,830

Activating Lyapunov-Based Feedback - Nonsmooth Control Lyapunov Functions$442,830

Funding body: ARC (Australian Research Council)

Funding body ARC (Australian Research Council)
Project Team Professor Christopher Kellett, Professor Lars Grune, Dr Sigurdur Hafstein, Doctor Bjoern Rueffer, Grunene, Lars, Hafstein, Sigurdur
Scheme Discovery Projects
Role Investigator
Funding Start 2016
Funding Finish 2018
GNo G1500106
Type Of Funding Aust Competitive - Commonwealth
Category 1CS
UON Y
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Research Supervision

Number of supervisions

Completed1
Current1

Current Supervision

Commenced Level of Study Research Title Program Supervisor Type
2018 Masters Investigating the Dynamics of Human Relationships and Emotions using a Mathematical Theory for Social Networks M Philosophy (Mathematics), Faculty of Science, The University of Newcastle Principal Supervisor

Past Supervision

Year Level of Study Research Title Program Supervisor Type
2019 PhD Advances in Stability Analysis for Nonlinear Discrete-Time Dynamical Systems PhD (Electrical Engineering), Faculty of Engineering and Built Environment, The University of Newcastle Co-Supervisor
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Research Collaborations

The map is a representation of a researchers co-authorship with collaborators across the globe. The map displays the number of publications against a country, where there is at least one co-author based in that country. Data is sourced from the University of Newcastle research publication management system (NURO) and may not fully represent the authors complete body of work.

Country Count of Publications
Germany 27
Australia 21
Japan 9
Netherlands 4
United States 4
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Dr Bjorn Ruffer

Position

Lecturer
School of Mathematical and Physical Sciences
Faculty of Science

Focus area

Mathematics

Contact Details

Email bjorn.ruffer@newcastle.edu.au
Phone (02) 491 38169
Fax (02) 492 16898
Links Personal webpage
Research Networks

Office

Room V227
Building Mathematics Building
Location Callaghan
University Drive
Callaghan, NSW 2308
Australia
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