Dr Bjorn Ruffer
Lecturer
School of Mathematical and Physical Sciences (Mathematics)
- Email:bjorn.ruffer@newcastle.edu.au
- Phone:(02) 491 38169
Career Summary
Biography
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 couple of European 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
- Decentralized and large scale systems
- Difference and functional equations
- Dynamical systems and ergodic theory
- Homotopy methods
- Operator theory
- Ordinary differential equations
- Robust, asymptotic, input-output stability
- Scalar and vector Lyapunov functions
- Semirings
- Systems theory and control
- Theory of error-correcting codes
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 |
|---|---|---|
| 28/04/2018 - 28/06/2018 | Visiting Professor | University of British Columbia Canada |
| 1/04/2014 - 1/09/2014 | Visiting Professor | University of Passau Faculty of Computer Science and Mathematics Germany |
Membership
| Dates | Title | Organisation / Department |
|---|---|---|
| 15/05/2018 - | Associate Editor | Automatica J. IFAC Netherlands |
| 1/01/2016 - | Member, SIAM | Society for Industrial and Applied Mathematics (SIAM) United States |
| 1/01/2010 - | Associate Editor | Systems & Control Letters Netherlands |
| 1/01/2008 - | Senior Member, IEEE | Institute of Electrical and Electronics Engineers 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 |
Teaching
| Code | Course | Role | Duration |
|---|---|---|---|
| SSP |
Study Leave School of Mathematical and Physical Sciences |
Currently on study leave. No more courses in 2018. | 1/05/2018 - 31/10/2018 |
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)
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| 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)
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| 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]
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| 2013 |
Ruffer BS, Van De Wouw N, Mueller M, 'Convergent systems vs. incremental stability', Systems and Control Letters, 62 277-285 (2013) [C1]
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Journal article (18 outputs)
| Year | Citation | Altmetrics | Link | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| 2019 |
Guiver C, Logemann H, Rüffer B, 'Small-gain stability theorems for positive Lur¿e inclusions', Positivity, 23 249-289 (2019) [C1]
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| 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]
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| 2018 |
Giladi O, Rüffer BS, 'A Perron¿Frobenius type result for integer maps and applications', Positivity, (2018) © 2018, Springer Nature Switzerland AG. It is shown that for certain maps, including concave maps, on the d-dimensional lattice of positive integer points, ¿approximate¿ eigenvect... [more] © 2018, Springer Nature Switzerland AG. It is shown that for certain maps, including concave maps, on the d-dimensional lattice of positive integer points, ¿approximate¿ eigenvectors can be found. Applications in epidemiology as well as distributed resource allocation are discussed as examples.
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| 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]
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| 2018 |
Tran DN, Ruffer BS, Kellett CM, 'Convergence Properties for Discrete-time Nonlinear Systems', IEEE Transactions on Automatic Control, (2018) IEEE Three similar convergence notions are considered. Two of them are the long established notions of convergent dynamics and incremental stability. The other is the more recent ... [more] IEEE Three similar convergence notions are considered. Two of them are the long established notions of convergent dynamics and incremental stability. The other is the more recent notion of contraction analysis. All three convergence notions require that all solutions of a system converge to each other. In this paper, we investigate the differences between these convergence properties for discrete-time, time-varying nonlinear systems by comparing the properties in pairs and using examples. We also demonstrate a time-varying smooth Lyapunov function characterization for each of these convergence notions. In addition, with appropriate assumptions, we provide several sufficient conditions to establish relationships between these properties in terms of Lyapunov functions.
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| 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]
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| 2013 |
Ruffer BS, Van De Wouw N, Mueller M, 'Convergent systems vs. incremental stability', Systems and Control Letters, 62 277-285 (2013) [C1]
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| 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]
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| 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.
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| 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]
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| 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)
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| 2010 |
Dashkovskiy SN, Ruffer BS, 'Local ISS of large-scale interconnections and estimates for stability regions', Systems and Control Letters, 59 241-247 (2010)
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| 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)
|
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| 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]
|
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| 2010 |
Rüffer BS, 'Small-Gain Conditions and the Comparison Principle', IEEE TRANSACTIONS ON AUTOMATIC CONTROL, 55 1732-1736 (2010)
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| 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)
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| 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)
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Grants and Funding
Summary
| Number of grants | 1 |
|---|---|
| Total funding | $463,459 |
Click on a grant title below to expand the full details for that specific grant.
20161 grants / $463,459
Activating Lyapunov-Based Feedback - Nonsmooth Control Lyapunov Functions$463,459
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 |
Research Supervision
Number of supervisions
Current Supervision
| Commenced | Level of Study | Research Title | Program | Supervisor Type |
|---|---|---|---|---|
| 2019 | PhD | Wave Scattering by Complex Geometries | PhD (Mathematics), Faculty of Science, The University of Newcastle | Co-Supervisor |
| 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 |
| 2015 | 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 |
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 | 25 | |
| Australia | 21 | |
| Japan | 9 | |
| Netherlands | 4 | |
| United States | 4 | |
| More... | ||
Dr Bjorn Ruffer
Position
Lecturer
School of Mathematical and Physical Sciences
Faculty of Science
Focus area
Mathematics
Contact Details
| 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 |
