# Professor Stuart Townley

## Professor in Applied Mathematics

**01326 255743**

**Environment and Sustainability Institute 1.39**

**Environment and Sustainability Institute, University of Exeter, Penryn Campus, Penryn, Cornwall, TR10 9FE, UK**

## Overview

I am particularly interested in dynamical systems and control: the study of things (mechanical, biological, electrical, etc.) which interact and evolve in time and can be predicted, managed and optimised. I've been the Chair in Applied Mathematics at the ESI since June 2011. I work closely with colleagues in the College of Engineering, Mathematics and Physical Sciences, as well as in the College of Life and Environmental Sciences, to understand natural and man-made systems.

I am also a member of the Mathematics department in the College of Engineering, Mathematics and Physical Sciences.

### Qualifications

**1987** PhD Engineering (University of Warwick)

**1983** BSc Mathematics (University of Warwick)

### Career

**2011 **Chair in Applied Mathematics, University of Exeter

**2003-2005** Head of Department in the School of Mathematics, University of Exeter

**2003-2005 **Associate Dean in the Postgraduate Faculty, University of Exeter

**1999 **Personal Chair, University of Exeter

**1996 **Reader, University of Exeter

**1990 **Lecturer, University of Exeter

**1988-1990 **Postdoctoral Researcher, University of Bath

**1986-1988 **Postdoctoral Researcher, University of Warwick

## Research

### Research interests

- Matrix algebra
- Signal processing
- Mathematical ecology and biology
- Inter-disciplinary mathematics
- Dynamical systems
- Population ecology
- Evolutionary biology
- Systems biology
- Energy systems and control

### Research projects

- 20th Century human demography: trends, transients and translocation (with Dr Markus Mueller & Prof Dave Hodgson)
- Risk assessment: an hospital admission (with Dr Adam Pollard & RCHT)
- Smart management of Physical and Natural Assests (with Dr Markus Muellerand NJW)
- The Demographic Buffering Hypothesis - Fact or Artefact? (with Prof Dave Hodgson)
- Adaptive control of POsitive Systems (with Dr Markus Mueller & Dr Chris Guiver)

## Publications

Key publications | Publications by category | Publications by year

### Key publications

**Guiver C, Edholm C, Jin Y, Mueller M, Powell J, Rebarber R, Tenhumberg B, Townley S**(2016). Simple Adaptive Control for Positive Linear Systems with Applications to Pest Management.

*SIAM Journal on Applied Mathematics*,

*76*(1), 238-275. Full text.

**Guiver C, Logemann H, Rebarber R, Bill A, Tenhumberg B, Hodgson D, Townley S**(2015). Integral control for population management.

*J Math Biol*,

*70*(5), 1015-1063. Abstract. Author URL. Full text.

**Elragig A, Townley S**(2012). A new necessary condition for Turing instabilities.

*Mathematical Biosciences*,

*239*(1), 131-138. Abstract.

**Townley S, Rebarber R, Tenhumberg B**(2012). Feedback control systems analysis of density dependent population dynamics.

*Systems and Control Letters*,

*61*(2), 309-315. Abstract.

**Stott I, Townley S, Hodgson DJ**(2011). A framework for studying transient dynamics of population projection matrix models.

*Ecol Lett*,

*14*(9), 959-970. Abstract. Author URL.

**Stott I, Franco M, Carslake D, Townley S, Hodgson D**(2010). Boom or bust? a comparative analysis of transient population dynamics in plants.

*Journal of Ecology*,

*98*(2), 302-311. Abstract.

### Publications by category

### Journal articles

**Argyropoulos A, Townley S, Upton PM, Dickinson S, Pollard AS**(2019). Identifying on admission patients likely to develop acute kidney injury in hospital.

*BMC Nephrol*,

*20*(1). Abstract. Author URL.

**Gianuca D, Votier SC, Pardo D, Wood AG, Sherley RB, Ireland L, Choquet R, Pradel R, Townley S, Forcada J, et al**(2019). Sex-specific effects of fisheries and climate on the demography of sexually dimorphic seabirds.

*J Anim Ecol*,

*88*(9), 1366-1378. Abstract. Author URL.

**Nicol‑Harper A, Dooley C, Packman D, Mueller M, Bijak J, Hodgson D, Townley S, Ezard T**(2018). Inferring transient dynamics of human populations from matrix non-normality.

*Population Ecology*Full text.

**Edholm CJ, Tenhumberg B, Guiver C, Jin Y, Townley S, Rebarber R**(2018). Management of invasive insect species using optimal control theory.

*Ecological Modelling*,

*381*, 36-45. Abstract.

**Guiver C, Packman D, Townley S**(2017). A necessary condition for dispersal driven growth of populations with discrete patch dynamics.

*J Theor Biol*,

*424*, 11-25. Abstract. Author URL.

**McDonald JL, Franco M, Townley S, Ezard THG, Jelbert K, Hodgson DJ**(2017). Divergent demographic strategies of plants in variable environments.

*Nature Ecology & Evolution*,

*1*(2). Full text.

**Gianuca D, Phillips RA, Townley S, Votier SC**(2017). Global patterns of sex- and age-specific variation in seabird bycatch.

*Biological Conservation*,

*205*, 60-76. Abstract. Full text.

**Guiver C, Logemann H, Townley S**(2017). Low-gain integral control for multi-input multioutput linear systems with input nonlinearities.

*IEEE Transactions on Automatic Control*,

*62*(9), 4776-4783. Abstract.

**Bill A, Guiver C, Logemann H, Townley S**(2017). The converging-input converging-state property for Lur’e systems.

*Mathematics of Control, Signals, and Systems*,

*29*(1). Abstract. Full text.

**Guiver C, Hodgson D, Townley S**(2016). A note on the eigenvectors of perturbed matrices with applications to linear positive systems.

*Linear Algebra and its Applications*,

*509*, 143-167. Abstract. Full text.

**Guiver C, Mueller M, Hodgson D, Townley S**(2016). Robust set-point regulation for ecological models with multiple management goals.

*J Math Biol*,

*72*(6), 1467-1529. Abstract. Author URL. Full text.

**Guiver C, Edholm C, Jin Y, Mueller M, Powell J, Rebarber R, Tenhumberg B, Townley S**(2016). Simple Adaptive Control for Positive Linear Systems with Applications to Pest Management.

*SIAM Journal on Applied Mathematics*,

*76*(1), 238-275. Full text.

**Bill A, Guiver C, Logemann H, Townley S**(2016). Stability of nonnegative Lur'e systems.

*SIAM Journal on Control and Optimization*,

*54*(3), 1176-1211. Abstract.

**Mcdonald JL, Stott I, Townley S, Hodgson DJ**(2016). Transients drive the demographic dynamics of plant populations in variable environments.

*Journal of Ecology*,

*104*(2), 306-314. Abstract. Full text.

**Guiver C, Logemann H, Rebarber R, Bill A, Tenhumberg B, Hodgson D, Townley S**(2015). Integral control for population management.

*J Math Biol*,

*70*(5), 1015-1063. Abstract. Author URL. Full text.

**Guiver C, Dreiwi H, Filannino D-M, Hodgson D, Lloyd S, Townley S**(2015). The role of population inertia in predicting the outcome of stage-structured biological invasions.

*Math Biosci*,

*265*, 1-11. Abstract. Author URL. Full text.

**Eager EA, Guiver C, Hodgson D, Rebarber R, Stott I, Townley S**(2014). Bounds on the dynamics of sink populations with noisy immigration.

*Theor Popul Biol*,

*92*, 88-96. Abstract. Author URL. Full text.

**Guiver C, Hodgson D, Townley S**(2014). Positive state controllability of positive linear systems.

*Systems and Control Letters*,

*65*(1), 23-29. Abstract. Full text.

**Kuijper B, Johnstone RA, Townley S**(2014). The evolution of multivariate maternal effects.

*PLoS Comput Biol*,

*10*(4). Abstract. Author URL. Full text.

**Townley S, Ezard THG**(2013). A G matrix analogue to capture the cumulative effects of nongenetic inheritance.

*J Evol Biol*,

*26*(6), 1234-1243. Abstract. Author URL.

**Elragig A, Townley S**(2012). A new necessary condition for Turing instabilities.

*Mathematical Biosciences*,

*239*(1), 131-138. Abstract.

**Stott I, Hodgson DJ, Townley S**(2012). Beyond sensitivity: nonlinear perturbation analysis of transient dynamics.

*METHODS IN ECOLOGY AND EVOLUTION*,

*3*(4), 673-684. Author URL.

**Townley S, Rebarber R, Tenhumberg B**(2012). Feedback control systems analysis of density dependent population dynamics.

*Systems and Control Letters*,

*61*(2), 309-315. Abstract.

**Rebarber R, Tenhumberg B, Townley S**(2012). Global asymptotic stability of density dependent integral population projection models.

*Theor Popul Biol*,

*81*(1), 81-87. Abstract. Author URL.

**Li G, Weiss G, Mueller M, Townley S, Belmont MR**(2012). Wave energy converter control by wave prediction and dynamic programming.

*Renewable Energy*,

*48*, 392-403. Abstract.

**Stott I, Hodgson DJ, Townley S**(2012). popdemo: an R package for population demography using projection matrix analysis.

*METHODS IN ECOLOGY AND EVOLUTION*,

*3*(5), 797-802. Author URL.

**Stott I, Townley S, Hodgson DJ**(2011). A framework for studying transient dynamics of population projection matrix models.

*Ecol Lett*,

*14*(9), 959-970. Abstract. Author URL.

**Stott I, Franco M, Carslake D, Townley S, Hodgson D**(2010). Boom or bust? a comparative analysis of transient population dynamics in plants.

*Journal of Ecology*,

*98*(2), 302-311. Abstract.

**Stott I, Townley S, Carslake D, Hodgson DJ**(2010). On reducibility and ergodicity of population projection matrix models.

*Methods in Ecology and Evolution*,

*1*, 242-252.

**Ke Z, Logemann H, Townley S**(2009). Adaptive sampled-data integral control of stable infinite-dimensional linear systems.

*Systems and Control Letters*

**Orosz G, Ashwin P, Townley S**(2009). Learning of spatiotemporal codes in a coupled oscillator system.

*IEEE Transactions on Neural Networks*Full text.

**Carslake D, Townley S, Hodgson DJ**(2009). Patterns and rules for sensitivity and elasticity in population projection matrices.

*Ecology*,

*90*(11), 3258-3267. Abstract. Author URL.

**Carslake D, Townley S, Hodgson DJ**(2009). Predicting the impact of stage-specific harvesting on population dynamics.

*J Anim Ecol*,

*78*(5), 1076-1085. Abstract. Author URL.

**Townley S, Hodgson DJ**(2008). Erratum et addendum: Transient amplification and attenuation in stage-structured population dynamics.

*Journal of Applied Ecology*,

*45*(6), 1836-1839. Abstract.

**Carslake D, Townley S, Hodgson DJ**(2008). Nonlinearity in eigenvalue-perturbation curves of simulated population projection matrices.

*Theor Popul Biol*,

*73*(4), 498-505. Abstract. Author URL.

**McCarthy D, Townley S, Hodgson D**(2008). On second order sensitivity for stage-based population projection matrix models.

*Theor Popul Biol*,

*74*(1), 68-73. Abstract. Author URL.

**Townley S, Hodgson DJ**(2008). Predicting transient amplification in perturbed ecological systems (vol 44, pg 1243, 2007).

*JOURNAL OF APPLIED ECOLOGY*,

*45*(6), 1836-1839. Author URL.

**Macclean,M.M,Carslake,D.J. Evans MR, Townley S, Hodgson DJ**(2008). The usefulness of sensitivity analysis for predicting the effects of cat predation on the population dynamics of their avian prey.

*IBIS*,

*150*, 100-113.

**Ashwin P, Orosz G, Wordsworth J, Townley S**(2007). Dynamics on networks of cluster states for globally coupled phase oscillators.

*SIAM Journal on Applied Dynamical Systems*,

*6*, 728-758. Author URL. Full text.

**Hodgson DJ, Carslake DJ, Kellie-Smith O, Townley S**(2007). Predicting transient amplification in disturbed natural systems.

*Journal of Applied Ecology*,

*44*(6), 1243-1251.

**Deines A, Peterson E, Boeckner D, Boyle J, Keighley A, Kogut J, Lubben J, Rebarber R, Ryan R, Tenhumberg B, et al**(2007). Robust population management under uncertainty for structured population models.

*Ecol Appl*,

*17*(8), 2175-2183. Abstract. Author URL.

**Rebarber R, Townley S**(2006). Robustness with respect to sampling for stabilization of Riesz spectral systems.

*IEEE Transactions on Automatic Control*,

*51*, 1519-1522.

**Hodgson D, Townley S, McCarthy D**(2006). Robustness: predicting the effects of life history perturbations on stage-structured population dynamics.

*Theor Popul Biol*,

*70*(2), 214-224. Abstract. Author URL.

**Ilchmann A, Townley S, Thuto M**(2005). Adaptive sampled-data tracking for input-constrained exothermic chemical reaction models.

*Systems and Control Letters*,

*54*(12), 1149-1161. Abstract.

**Townley SB, Lamooki JRR, Osinga HM**(2005). Bifurcations and limit dynamics in adaptive control systems.

*International Journal of Bifurcation and Chaos*,

*15*(5), 1641-1664.

**Townley SB, Rebarber R, Logemann H**(2005). Generalized sampled-data stabilization of well-posed linear infinite-dimensional systems.

*SIAM Journal on Control and Optimization*,

*44*(4), 1345-1369.

**Emirsajlow Z, Townley S**(2005). On application of the implemented semigroup to a problem arising in optimal control.

*International Journal of Control*,

*78*(4), 298-310. Abstract.

**Thuto, M.V. Ilchmann, A.**(2004). Input constrained adaptive l-tracking with applications to exothermic chemical reactor models.

*SIAM Journal on Control and Optimization*,

*43*(1), 154-173.

**Hodgson DJ, Townley S**(2004). Linking management changes to population dynamic responses: the transfer function of a projection matrix perturbation.

*Journal of Applied Ecology*,

*41*(6), 1155-1161.

**Osinga HM, Lamooki GRR, Townley S**(2004). Numerical approximations of strong (un)stable manifolds.

*Dynamical Systems*,

*19*, 195-215.

**Logemann, H.**(2003). Adaptive low-gain integral control of multivariable well-posed linear systems.

*SIAM Journal on Control and Optimization*,

*41*(6), 1722-1732.

**Ozdemir N, Townley S**(2003). Integral-control by variable sampling based on steady state data.

*Automatica*,

*39*, 135-140.

**Townley SB, Crauel H, Matsikis I**(2003). Noise assisted high gain stabilization: Almost surely or in second mean.

*SIAM Journal on Control and Optimization*,

*42*(5), 1834-1853.

**Townley TY, Townley S, Owens DH, Yu H**(2003). Norm optimal iterative learning plus prediction control.

*"Proceedings of the 9th IEEE International Conference on Methods and Models in Automation and Robotics, August 2003"*,

*1*, 539-544.

**Lamooki GRR, Townley S**(2003). Partial stability in back-stepping and adaptive control.

*"'Proceedings of the 9th IEEE International Conference on Methods and Models in Automation and Robotics, August 2003'"*,

*1*, 491-496.

**Townley SB, Logemann H, Rebarber R**(2003). Stability of infinite-dimensional sampled-data systems.

*Transactions of the American Mathematical Society*,

*355*(8), 3301-3328.

**Rebarber R, Townley S**(2002). Nonrobustness of closed-loop stability for infinite-dimensional systems under sample and hold.

*IEEE Transactions on Automatic Control*,

*47*(8), 1381-1385. Abstract.

**Rebarber R, Townley S**(2001). Robustness of closed-loop stability for infinite-dimensional systems under sample and hold - counterexamples.

*"Proc. Conference on Decision and Control, Sydney, December 2000"*, 3290-3295.

**Ozdemir N, Townley S**(2001). Variable sampling integral control of infinite-dimensional systems.

*"'Proc. Conference on Decision and Control, Sydney, December 2000'"*, 3284-3289.

**Lefevre L, Georges D, Emirsjlow Z, Townley S**(2000). Discussion on: 'From PDEs with boundary control to the abstract state equation with an unbounded input operator: a tutorial' by Z. Emirsjlow and S. Townley.

*EUROPEAN JOURNAL OF CONTROL*,

*6*(1), 50-53. Author URL.

**Townley S, Ilchmann A, Weiss MG, McClements W, Ruiz AC, Owens DH, Pratzel-Wolters D**(2000). Existence and learning of oscillations in recurrent neural networks.

*IEEE Trans Neural Netw*,

*11*(1), 205-214. Abstract. Author URL.

**Emirsjlow Z, Townley S**(2000). From PDEs with boundary control to the abstract state equation with an unbounded input operator: a tutorial.

*European Journal of Control*,

*6*(1), 27-49. Abstract.

**Ilchmann A, Townley S**(1999). Adaptive high-gain λ-tracking with variable sampling rate.

*Systems and Control Letters*,

*36*(4), 285-293. Abstract.

**Ilchmann A, Townley S**(1999). Adaptive sampling control of high-gain stabilizable systems.

*IEEE Transactions on Automatic Control*,

*44*(10), 1961-1966. Abstract.

**Townley S**(1999). An example of a globally stabilizing adaptive controller with a generically destabilizing parameter estimate.

*IEEE Transactions on Automatic Control*,

*44*(11), 2238-2241. Abstract.

**Logemann H, Ryan EP, Townley S**(1999). Integral control of linear systems with actuator nonlinearities: Lower bounds for the maximal regulating gain.

*IEEE Transactions on Automatic Control*,

*44*(6), 1315-1319. Abstract.

**Rebarber R, Townley S**(1999). Robustness with respect to delays for exponential stability of distributed parameter systems.

*SIAM Journal on Control and Optimization*,

*37*(1), 230-244. Abstract.

**Ruiz A, Owens DH, Townley S**(1998). Existence, learning, and replication of periodic motions in recurrent neural networks.

*IEEE Trans Neural Netw*,

*9*(4), 651-661. Abstract. Author URL.

**Rebarber R, Townley S**(1998). Generalized sampled data feedback control of distributed parameter systems.

*Systems and Control Letters*,

*34*(5), 229-240. Abstract.

**Logemann H, Ryan EP, Townley S**(1998). Integral control of infinite-dimensional linear systems subject to input saturation.

*SIAM Journal on Control and Optimization*,

*36*(6), 1940-1961. Abstract.

**Logemann H, Townley S**(1997). Adaptive control of infinite-dimensional systems without parameter estimation: an overview.

*IMA Journal of Mathematical Control and Information*,

*14*(2), 175-206. Abstract.

**Logemann H, Townley S**(1997). Adaptive integral control of time-delay systems.

*IEE Proceedings: Control Theory and Applications*,

*144*(6), 531-536. Abstract.

**Logemann H, Townley S**(1997). Discrete-time low-gain control of uncertain infinite-dimensional systems.

*IEEE Transactions on Automatic Control*,

*42*(1), 22-37. Abstract.

**Logemann H, Townley S**(1997). Low-gain control of uncertain regular linear systems.

*SIAM Journal on Control and Optimization*,

*35*(1), 78-116. Abstract.

**Rebarber R, Townley S**(1997). Stabilization of distributed parameter systems by piecewise polynomial control.

*IEEE Transactions on Automatic Control*,

*42*(9), 1254-1257. Abstract.

**Townley S, Kamstra M**(1996). Integral control with saturating input.

*IEE Conference Publication*(427 /2), 805-808. Abstract.

**Ruiz A, Owens DH, Townley S**(1996). Learning periodic signals with recurrent neural.

*IEE Conference Publication*(427 /2), 1131-1136. Abstract.

**Logemann H, Townley S**(1996). Low gain control of uncertain distributed parameter systems: Part 1 & Part 2.

*IEE Colloquium (Digest)*(139). Abstract.

**Emirsajlow Z, Pritchard AJ, Townley S**(1996). On structured perturbations for two classes of linear infinite-dimensional systems.

*Dynamics and Control*,

*6*(3), 227-261. Abstract.

**Triantafillidis S, Leach JA, Owens DH, Townley S**(1996). Qualitative dynamics, root-loci and asymptotic structure of universal adaptive stabilizers.

*IMA Journal of Mathematical Control and Information*,

*13*(3), 251-278. Abstract.

**Logemann H, Townley S**(1996). The effect of small delays in the feedback loop on the stability of neutral systems.

*Systems and Control Letters*,

*27*(5), 267-274. Abstract.

**Townley S**(1996). Topological aspects of universal adaptive stabilization.

*SIAM Journal on Control and Optimization*,

*34*(3), 1044-1070. Abstract.

**Leach JA, Triantafillidis S, Owens DH, Townley S**(1995). Dynamics of universal adaptive stabilization: computational and analytical studies.

*Control, theory and advanced technology*,

*10*(4 pt 4), 1689-1716. Abstract.

**Triantafillidis S, Leach JA, Owens DH, Townley S**(1995). Limit systems, limit gains and non-generic behaviours arising in adaptive stabilizing control.

*Dynamics and Stability of Systems*,

*10*(3), 233-254. Abstract.

**Rebarber R, Townley S**(1995). Robustness and continuity of the spectrum for uncertain distributed parameter systems.

*Automatica*,

*31*(11), 1533-1546. Abstract.

**Townley S**(1995). Simple adaptive stabilization of output feedback stabilizable distributed parameter systems.

*Dynamics and Control*,

*5*(2), 107-123. Abstract.

**Leach JA, Triantafillidis S, Owens DH, Townley S**(1995). The dynamics of universal adaptive stabilization: Computational and analytical studies.

*CONTROL-THEORY AND ADVANCED TECHNOLOGY*,

*10*(4), 1689-1716. Author URL.

**RYAN EP, TOWNLEY S**(1993). NONLINEAR UNCERTAIN SYSTEMS AND ROBUSTNESS OPTIMIZATION.

*INTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL*,

*3*(3), 241-260. Author URL.

**Hicks AC, Townley S**(1993). On exact solutions of differential equations arising in universal adaptive stabilization.

*Systems and Control Letters*,

*20*(2), 117-129. Abstract.

**Ilchmann A, Townley S**(1993). Simple adaptive stabilization of high-gain stabilizable systems.

*Systems and Control Letters*,

*20*(3), 189-198. Abstract.

**Townley S, Owens DH**(1991). A note on the problem of multivariable adaptive tracking.

*IMA Journal of Mathematical Control and Information*,

*8*(4), 389-395. Abstract.

**Townley S, Ryan EP**(1991). On the supremally regulated complex stability radius as a real robustness measure.

*Systems and Control Letters*,

*16*(4), 249-259. Abstract.

**Pritchard AJ, Townley S**(1991). Robustness optimization for uncertain infinite-dimensional systems with unbounded inputs.

*IMA Journal of Mathematical Control and Information*,

*8*(2), 121-133. Abstract.

**HINRICHSEN D, PRITCHARD AJ, TOWNLEY SB**(1990). RICCATI EQUATION APPROACH TO MAXIMIZING THE COMPLEX STABILITY RADIUS BY STATE FEEDBACK.

*INTERNATIONAL JOURNAL OF CONTROL*,

*52*(4), 769-794. Author URL.

**Townley S**(1990). Stability radius optimization: a geometric approach.

*Systems and Control Letters*,

*14*(3), 199-207. Abstract.

**Pritchard AJ, Townley S**(1989). Robustness of linear systems.

*Journal of Differential Equations*,

*77*(2), 254-286. Abstract.

**Pritchard AJ, Townley S**(1988). Robust compensator design via structured stability radii.

*Systems and Control Letters*,

*11*(1), 33-37. Abstract.

**PRITCHARD AJ, TOWNLEY S**(1987). A STABILITY RADIUS FOR INFINITE DIMENSIONAL SYSTEMS.

*LECTURE NOTES IN CONTROL AND INFORMATION SCIENCES*,

*102*, 272-291. Author URL.

**Chapman MJ, Pritchard AJ, Townley SB**(1987). Modelling linear distributed parameter systems.

*Systems Science*,

*13*(3-4), 37-50. Abstract.

**Pritchard AJ, Townley S**(1987). ROBUSTNESS OF INFINITE DIMENSIONAL SYSTEMS.

*IFAC Proceedings Series*(3), 459-462. Abstract.

### Conferences

**Ilchmann A, Townley S**(2015). Adaptive high-gain fast-sampling P-control. Abstract.

**Orosz G, Ashwin P, Wordsworth J, Townley S**(2007). Cluster synchronization, switching and spatio-temporal coding in a phase oscillator network. Author URL.

**Ilchmann A, Thuto MV, Townley S**(2001). Lambda-tracking for exothermic chemical reactions with saturating inputs.

**Ilchmann A, Thuto M, Townley S**(2001). λ-Tracking for exothermic chemical reactions with saturating inputs. Abstract.

**Rebarber R, Townley S**(2000). Robustness of closed-loop stability for infinite dimensional systems under sample and hold - Counterexamples. Abstract.

**Logemann H, Ryan EP, Townley S**(1998). Low-gain integral control of linear distributed parameter systems subject to input saturation. Abstract.

**Ilchmann A, Townley S**(1997). Adaptive high-gain fast-sampling P-control. Abstract.

**Ruiz A, Owens DH, Townley S**(1996). Existence of limit cycles in recurrent neural networks. Abstract.

**Logemann H, Townley S, IEEE**(1995). Adaptive low-gain sampled-data control of DPS. Author URL.

**Townley S, Owens DH, Triantafillidis S, Leach JA**(1995). Local and limiting analysis of stable universal adaptive dynamics. Abstract.

**Townley S**(1995). Topological aspects of universal adaptive stabilization. Abstract.

**TOWNLEY S**(1993). ROBUST STABILITY RADII FOR DISTRIBUTED-PARAMETER SYSTEMS - a SURVEY. Author URL.

**TOWNLEY S, IEEE**(1992). GENERIC PROPERTIES OF UNIVERSAL ADAPTIVE STABILIZATION SCHEMES. Author URL.

**Ryan EP, Townley S**(1990). Non-linear systems: Robustness optimization and universal adaptive stabilization. Abstract.

**PRITCHARD AJ, TOWNLEY S**(1990). REAL STABILITY RADII FOR INFINITE DIMENSIONAL SYSTEMS. Author URL.

### Publications by year

### 2019

**Argyropoulos A, Townley S, Upton PM, Dickinson S, Pollard AS**(2019). Identifying on admission patients likely to develop acute kidney injury in hospital.

*BMC Nephrol*,

*20*(1). Abstract. Author URL.

**Gianuca D, Votier SC, Pardo D, Wood AG, Sherley RB, Ireland L, Choquet R, Pradel R, Townley S, Forcada J, et al**(2019). Sex-specific effects of fisheries and climate on the demography of sexually dimorphic seabirds.

*J Anim Ecol*,

*88*(9), 1366-1378. Abstract. Author URL.

### 2018

**Nicol‑Harper A, Dooley C, Packman D, Mueller M, Bijak J, Hodgson D, Townley S, Ezard T**(2018). Inferring transient dynamics of human populations from matrix non-normality.

*Population Ecology*Full text.

**Edholm CJ, Tenhumberg B, Guiver C, Jin Y, Townley S, Rebarber R**(2018). Management of invasive insect species using optimal control theory.

*Ecological Modelling*,

*381*, 36-45. Abstract.

### 2017

**Guiver C, Packman D, Townley S**(2017). A necessary condition for dispersal driven growth of populations with discrete patch dynamics.

*J Theor Biol*,

*424*, 11-25. Abstract. Author URL.

**McDonald JL, Franco M, Townley S, Ezard THG, Jelbert K, Hodgson DJ**(2017). Divergent demographic strategies of plants in variable environments.

*Nature Ecology & Evolution*,

*1*(2). Full text.

**Gianuca D, Phillips RA, Townley S, Votier SC**(2017). Global patterns of sex- and age-specific variation in seabird bycatch.

*Biological Conservation*,

*205*, 60-76. Abstract. Full text.

**Guiver C, Logemann H, Townley S**(2017). Low-gain integral control for multi-input multioutput linear systems with input nonlinearities.

*IEEE Transactions on Automatic Control*,

*62*(9), 4776-4783. Abstract.

**Bill A, Guiver C, Logemann H, Townley S**(2017). The converging-input converging-state property for Lur’e systems.

*Mathematics of Control, Signals, and Systems*,

*29*(1). Abstract. Full text.

### 2016

**Guiver C, Hodgson D, Townley S**(2016). A note on the eigenvectors of perturbed matrices with applications to linear positive systems.

*Linear Algebra and its Applications*,

*509*, 143-167. Abstract. Full text.

**Guiver C, Mueller M, Hodgson D, Townley S**(2016). Robust set-point regulation for ecological models with multiple management goals.

*J Math Biol*,

*72*(6), 1467-1529. Abstract. Author URL. Full text.

**Guiver C, Edholm C, Jin Y, Mueller M, Powell J, Rebarber R, Tenhumberg B, Townley S**(2016). Simple Adaptive Control for Positive Linear Systems with Applications to Pest Management.

*SIAM Journal on Applied Mathematics*,

*76*(1), 238-275. Full text.

**Bill A, Guiver C, Logemann H, Townley S**(2016). Stability of nonnegative Lur'e systems.

*SIAM Journal on Control and Optimization*,

*54*(3), 1176-1211. Abstract.

**Mcdonald JL, Stott I, Townley S, Hodgson DJ**(2016). Transients drive the demographic dynamics of plant populations in variable environments.

*Journal of Ecology*,

*104*(2), 306-314. Abstract. Full text.

### 2015

**Ilchmann A, Townley S**(2015). Adaptive high-gain fast-sampling P-control. Abstract.

**Guiver C, Logemann H, Rebarber R, Bill A, Tenhumberg B, Hodgson D, Townley S**(2015). Integral control for population management.

*J Math Biol*,

*70*(5), 1015-1063. Abstract. Author URL. Full text.

**Guiver C, Dreiwi H, Filannino D-M, Hodgson D, Lloyd S, Townley S**(2015). The role of population inertia in predicting the outcome of stage-structured biological invasions.

*Math Biosci*,

*265*, 1-11. Abstract. Author URL. Full text.

### 2014

**Eager EA, Guiver C, Hodgson D, Rebarber R, Stott I, Townley S**(2014). Bounds on the dynamics of sink populations with noisy immigration.

*Theor Popul Biol*,

*92*, 88-96. Abstract. Author URL. Full text.

**Guiver C, Hodgson D, Townley S**(2014). Positive state controllability of positive linear systems.

*Systems and Control Letters*,

*65*(1), 23-29. Abstract. Full text.

**Kuijper B, Johnstone RA, Townley S**(2014). The evolution of multivariate maternal effects.

*PLoS Comput Biol*,

*10*(4). Abstract. Author URL. Full text.

### 2013

**Townley S, Ezard THG**(2013). A G matrix analogue to capture the cumulative effects of nongenetic inheritance.

*J Evol Biol*,

*26*(6), 1234-1243. Abstract. Author URL.

### 2012

**Elragig A, Townley S**(2012). A new necessary condition for Turing instabilities.

*Mathematical Biosciences*,

*239*(1), 131-138. Abstract.

**Stott I, Hodgson DJ, Townley S**(2012). Beyond sensitivity: nonlinear perturbation analysis of transient dynamics.

*METHODS IN ECOLOGY AND EVOLUTION*,

*3*(4), 673-684. Author URL.

**Townley S, Rebarber R, Tenhumberg B**(2012). Feedback control systems analysis of density dependent population dynamics.

*Systems and Control Letters*,

*61*(2), 309-315. Abstract.

**Rebarber R, Tenhumberg B, Townley S**(2012). Global asymptotic stability of density dependent integral population projection models.

*Theor Popul Biol*,

*81*(1), 81-87. Abstract. Author URL.

**Li G, Weiss G, Mueller M, Townley S, Belmont MR**(2012). Wave energy converter control by wave prediction and dynamic programming.

*Renewable Energy*,

*48*, 392-403. Abstract.

**Stott I, Hodgson DJ, Townley S**(2012). popdemo: an R package for population demography using projection matrix analysis.

*METHODS IN ECOLOGY AND EVOLUTION*,

*3*(5), 797-802. Author URL.

### 2011

**Stott I, Townley S, Hodgson DJ**(2011). A framework for studying transient dynamics of population projection matrix models.

*Ecol Lett*,

*14*(9), 959-970. Abstract. Author URL.

### 2010

**Stott I, Franco M, Carslake D, Townley S, Hodgson D**(2010). Boom or bust? a comparative analysis of transient population dynamics in plants.

*Journal of Ecology*,

*98*(2), 302-311. Abstract.

**Stott I, Townley S, Carslake D, Hodgson DJ**(2010). On reducibility and ergodicity of population projection matrix models.

*Methods in Ecology and Evolution*,

*1*, 242-252.

### 2009

**Ke Z, Logemann H, Townley S**(2009). Adaptive sampled-data integral control of stable infinite-dimensional linear systems.

*Systems and Control Letters*

**Orosz G, Ashwin P, Townley S**(2009). Learning of spatiotemporal codes in a coupled oscillator system.

*IEEE Transactions on Neural Networks*Full text.

**Lubben J, Boeckner D, Rebarber R, Townley S, Tenhumberg B**(2009). Parameterizing the growth-decline boundary for uncertain population projection models.

*THEOR POPUL BIOL*,

*75*(2-3), 85-97.

**Carslake D, Townley S, Hodgson DJ**(2009). Patterns and rules for sensitivity and elasticity in population projection matrices.

*Ecology*,

*90*(11), 3258-3267. Abstract. Author URL.

**Carslake D, Townley S, Hodgson DJ**(2009). Predicting the impact of stage-specific harvesting on population dynamics.

*J Anim Ecol*,

*78*(5), 1076-1085. Abstract. Author URL.

### 2008

**Townley S, Hodgson DJ**(2008). Erratum et addendum: Transient amplification and attenuation in stage-structured population dynamics.

*Journal of Applied Ecology*,

*45*(6), 1836-1839. Abstract.

**Carslake D, Townley S, Hodgson DJ**(2008). Nonlinearity in eigenvalue-perturbation curves of simulated population projection matrices.

*Theor Popul Biol*,

*73*(4), 498-505. Abstract. Author URL.

**McCarthy D, Townley S, Hodgson D**(2008). On second order sensitivity for stage-based population projection matrix models.

*Theor Popul Biol*,

*74*(1), 68-73. Abstract. Author URL.

**Townley S, Hodgson DJ**(2008). Predicting transient amplification in perturbed ecological systems (vol 44, pg 1243, 2007).

*JOURNAL OF APPLIED ECOLOGY*,

*45*(6), 1836-1839. Author URL.

**Macclean,M.M,Carslake,D.J. Evans MR, Townley S, Hodgson DJ**(2008). The usefulness of sensitivity analysis for predicting the effects of cat predation on the population dynamics of their avian prey.

*IBIS*,

*150*, 100-113.

### 2007

**Orosz G, Ashwin P, Wordsworth J, Townley S**(2007). Cluster synchronization, switching and spatio-temporal coding in a phase oscillator network. Author URL.

**Ashwin P, Orosz G, Wordsworth J, Townley S**(2007). Dynamics on networks of cluster states for globally coupled phase oscillators.

*SIAM Journal on Applied Dynamical Systems*,

*6*, 728-758. Author URL. Full text.

**Hodgson DJ, Carslake DJ, Kellie-Smith O, Townley S**(2007). Predicting transient amplification in disturbed natural systems.

*Journal of Applied Ecology*,

*44*(6), 1243-1251.

**Deines A, Peterson E, Boeckner D, Boyle J, Keighley A, Kogut J, Lubben J, Rebarber R, Ryan R, Tenhumberg B, et al**(2007). Robust population management under uncertainty for structured population models.

*Ecol Appl*,

*17*(8), 2175-2183. Abstract. Author URL.

### 2006

**Rebarber R, Townley S**(2006). Robustness with respect to sampling for stabilization of Riesz spectral systems.

*IEEE Transactions on Automatic Control*,

*51*, 1519-1522.

**Hodgson D, Townley S, McCarthy D**(2006). Robustness: predicting the effects of life history perturbations on stage-structured population dynamics.

*Theor Popul Biol*,

*70*(2), 214-224. Abstract. Author URL.

### 2005

**Ilchmann A, Townley S, Thuto M**(2005). Adaptive sampled-data tracking for input-constrained exothermic chemical reaction models.

*Systems and Control Letters*,

*54*(12), 1149-1161. Abstract.

**Townley SB, Lamooki JRR, Osinga HM**(2005). Bifurcations and limit dynamics in adaptive control systems.

*International Journal of Bifurcation and Chaos*,

*15*(5), 1641-1664.

**Townley SB, Rebarber R, Logemann H**(2005). Generalized sampled-data stabilization of well-posed linear infinite-dimensional systems.

*SIAM Journal on Control and Optimization*,

*44*(4), 1345-1369.

**Emirsajlow Z, Townley S**(2005). On application of the implemented semigroup to a problem arising in optimal control.

*International Journal of Control*,

*78*(4), 298-310. Abstract.

### 2004

**Thuto, M.V. Ilchmann, A.**(2004). Input constrained adaptive l-tracking with applications to exothermic chemical reactor models.

*SIAM Journal on Control and Optimization*,

*43*(1), 154-173.

**Hodgson DJ, Townley S**(2004). Linking management changes to population dynamic responses: the transfer function of a projection matrix perturbation.

*Journal of Applied Ecology*,

*41*(6), 1155-1161.

**Osinga HM, Lamooki GRR, Townley S**(2004). Numerical approximations of strong (un)stable manifolds.

*Dynamical Systems*,

*19*, 195-215.

### 2003

**Logemann, H.**(2003). Adaptive low-gain integral control of multivariable well-posed linear systems.

*SIAM Journal on Control and Optimization*,

*41*(6), 1722-1732.

**Ozdemir N, Townley S**(2003). Integral-control by variable sampling based on steady state data.

*Automatica*,

*39*, 135-140.

**Townley SB, Crauel H, Matsikis I**(2003). Noise assisted high gain stabilization: Almost surely or in second mean.

*SIAM Journal on Control and Optimization*,

*42*(5), 1834-1853.

**Townley TY, Townley S, Owens DH, Yu H**(2003). Norm optimal iterative learning plus prediction control.

*"Proceedings of the 9th IEEE International Conference on Methods and Models in Automation and Robotics, August 2003"*,

*1*, 539-544.

**Lamooki GRR, Townley S**(2003). Partial stability in back-stepping and adaptive control.

*"'Proceedings of the 9th IEEE International Conference on Methods and Models in Automation and Robotics, August 2003'"*,

*1*, 491-496.

**Townley SB, Logemann H, Rebarber R**(2003). Stability of infinite-dimensional sampled-data systems.

*Transactions of the American Mathematical Society*,

*355*(8), 3301-3328.

### 2002

**Rebarber R, Townley S**(2002). Nonrobustness of closed-loop stability for infinite-dimensional systems under sample and hold.

*IEEE Transactions on Automatic Control*,

*47*(8), 1381-1385. Abstract.

### 2001

**Ilchmann A, Thuto MV, Townley S**(2001). Lambda-tracking for exothermic chemical reactions with saturating inputs.

**Rebarber R, Townley S**(2001). Robustness of closed-loop stability for infinite-dimensional systems under sample and hold - counterexamples.

*"Proc. Conference on Decision and Control, Sydney, December 2000"*, 3290-3295.

**Ozdemir N, Townley S**(2001). Variable sampling integral control of infinite-dimensional systems.

*"'Proc. Conference on Decision and Control, Sydney, December 2000'"*, 3284-3289.

**Ilchmann A, Thuto M, Townley S**(2001). λ-Tracking for exothermic chemical reactions with saturating inputs. Abstract.

### 2000

**Lefevre L, Georges D, Emirsjlow Z, Townley S**(2000). Discussion on: 'From PDEs with boundary control to the abstract state equation with an unbounded input operator: a tutorial' by Z. Emirsjlow and S. Townley.

*EUROPEAN JOURNAL OF CONTROL*,

*6*(1), 50-53. Author URL.

**Townley S, Ilchmann A, Weiss MG, McClements W, Ruiz AC, Owens DH, Pratzel-Wolters D**(2000). Existence and learning of oscillations in recurrent neural networks.

*IEEE Trans Neural Netw*,

*11*(1), 205-214. Abstract. Author URL.

**Emirsjlow Z, Townley S**(2000). From PDEs with boundary control to the abstract state equation with an unbounded input operator: a tutorial.

*European Journal of Control*,

*6*(1), 27-49. Abstract.

**Rebarber R, Townley S**(2000). Robustness of closed-loop stability for infinite dimensional systems under sample and hold - Counterexamples. Abstract.

### 1999

**Ilchmann A, Townley S**(1999). Adaptive high-gain λ-tracking with variable sampling rate.

*Systems and Control Letters*,

*36*(4), 285-293. Abstract.

**Ilchmann A, Townley S**(1999). Adaptive sampling control of high-gain stabilizable systems.

*IEEE Transactions on Automatic Control*,

*44*(10), 1961-1966. Abstract.

**Townley S**(1999). An example of a globally stabilizing adaptive controller with a generically destabilizing parameter estimate.

*IEEE Transactions on Automatic Control*,

*44*(11), 2238-2241. Abstract.

**Logemann H, Ryan EP, Townley S**(1999). Integral control of linear systems with actuator nonlinearities: Lower bounds for the maximal regulating gain.

*IEEE Transactions on Automatic Control*,

*44*(6), 1315-1319. Abstract.

**Rebarber R, Townley S**(1999). Robustness with respect to delays for exponential stability of distributed parameter systems.

*SIAM Journal on Control and Optimization*,

*37*(1), 230-244. Abstract.

### 1998

**Ruiz A, Owens DH, Townley S**(1998). Existence, learning, and replication of periodic motions in recurrent neural networks.

*IEEE Trans Neural Netw*,

*9*(4), 651-661. Abstract. Author URL.

**Rebarber R, Townley S**(1998). Generalized sampled data feedback control of distributed parameter systems.

*Systems and Control Letters*,

*34*(5), 229-240. Abstract.

**Logemann H, Ryan EP, Townley S**(1998). Integral control of infinite-dimensional linear systems subject to input saturation.

*SIAM Journal on Control and Optimization*,

*36*(6), 1940-1961. Abstract.

**Logemann H, Ryan EP, Townley S**(1998). Low-gain integral control of linear distributed parameter systems subject to input saturation. Abstract.

### 1997

**Logemann H, Townley S**(1997). Adaptive control of infinite-dimensional systems without parameter estimation: an overview.

*IMA Journal of Mathematical Control and Information*,

*14*(2), 175-206. Abstract.

**Ilchmann A, Townley S**(1997). Adaptive high-gain fast-sampling P-control. Abstract.

**Logemann H, Townley S**(1997). Adaptive integral control of time-delay systems.

*IEE Proceedings: Control Theory and Applications*,

*144*(6), 531-536. Abstract.

**Logemann H, Townley S**(1997). Discrete-time low-gain control of uncertain infinite-dimensional systems.

*IEEE Transactions on Automatic Control*,

*42*(1), 22-37. Abstract.

**Logemann H, Townley S**(1997). Low-gain control of uncertain regular linear systems.

*SIAM Journal on Control and Optimization*,

*35*(1), 78-116. Abstract.

**Rebarber R, Townley S**(1997). Stabilization of distributed parameter systems by piecewise polynomial control.

*IEEE Transactions on Automatic Control*,

*42*(9), 1254-1257. Abstract.

### 1996

**Ruiz A, Owens DH, Townley S**(1996). Existence of limit cycles in recurrent neural networks. Abstract.

**Townley S, Kamstra M**(1996). Integral control with saturating input.

*IEE Conference Publication*(427 /2), 805-808. Abstract.

**Ruiz A, Owens DH, Townley S**(1996). Learning periodic signals with recurrent neural.

*IEE Conference Publication*(427 /2), 1131-1136. Abstract.

**Logemann H, Townley S**(1996). Low gain control of uncertain distributed parameter systems: Part 1 & Part 2.

*IEE Colloquium (Digest)*(139). Abstract.

**Emirsajlow Z, Pritchard AJ, Townley S**(1996). On structured perturbations for two classes of linear infinite-dimensional systems.

*Dynamics and Control*,

*6*(3), 227-261. Abstract.

**Triantafillidis S, Leach JA, Owens DH, Townley S**(1996). Qualitative dynamics, root-loci and asymptotic structure of universal adaptive stabilizers.

*IMA Journal of Mathematical Control and Information*,

*13*(3), 251-278. Abstract.

**Logemann H, Townley S**(1996). The effect of small delays in the feedback loop on the stability of neutral systems.

*Systems and Control Letters*,

*27*(5), 267-274. Abstract.

**Townley S**(1996). Topological aspects of universal adaptive stabilization.

*SIAM Journal on Control and Optimization*,

*34*(3), 1044-1070. Abstract.

### 1995

**Logemann H, Townley S, IEEE**(1995). Adaptive low-gain sampled-data control of DPS. Author URL.

**Leach JA, Triantafillidis S, Owens DH, Townley S**(1995). Dynamics of universal adaptive stabilization: computational and analytical studies.

*Control, theory and advanced technology*,

*10*(4 pt 4), 1689-1716. Abstract.

**Triantafillidis S, Leach JA, Owens DH, Townley S**(1995). Limit systems, limit gains and non-generic behaviours arising in adaptive stabilizing control.

*Dynamics and Stability of Systems*,

*10*(3), 233-254. Abstract.

**Townley S, Owens DH, Triantafillidis S, Leach JA**(1995). Local and limiting analysis of stable universal adaptive dynamics. Abstract.

**Rebarber R, Townley S**(1995). Robustness and continuity of the spectrum for uncertain distributed parameter systems.

*Automatica*,

*31*(11), 1533-1546. Abstract.

**Townley S**(1995). Simple adaptive stabilization of output feedback stabilizable distributed parameter systems.

*Dynamics and Control*,

*5*(2), 107-123. Abstract.

**Leach JA, Triantafillidis S, Owens DH, Townley S**(1995). The dynamics of universal adaptive stabilization: Computational and analytical studies.

*CONTROL-THEORY AND ADVANCED TECHNOLOGY*,

*10*(4), 1689-1716. Author URL.

**Townley S**(1995). Topological aspects of universal adaptive stabilization. Abstract.

### 1993

**RYAN EP, TOWNLEY S**(1993). NONLINEAR UNCERTAIN SYSTEMS AND ROBUSTNESS OPTIMIZATION.

*INTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL*,

*3*(3), 241-260. Author URL.

**Hicks AC, Townley S**(1993). On exact solutions of differential equations arising in universal adaptive stabilization.

*Systems and Control Letters*,

*20*(2), 117-129. Abstract.

**TOWNLEY S**(1993). ROBUST STABILITY RADII FOR DISTRIBUTED-PARAMETER SYSTEMS - a SURVEY. Author URL.

**Ilchmann A, Townley S**(1993). Simple adaptive stabilization of high-gain stabilizable systems.

*Systems and Control Letters*,

*20*(3), 189-198. Abstract.

### 1992

**TOWNLEY S, IEEE**(1992). GENERIC PROPERTIES OF UNIVERSAL ADAPTIVE STABILIZATION SCHEMES. Author URL.

### 1991

**Townley S, Owens DH**(1991). A note on the problem of multivariable adaptive tracking.

*IMA Journal of Mathematical Control and Information*,

*8*(4), 389-395. Abstract.

**Townley S, Ryan EP**(1991). On the supremally regulated complex stability radius as a real robustness measure.

*Systems and Control Letters*,

*16*(4), 249-259. Abstract.

**Pritchard AJ, Townley S**(1991). Robustness optimization for uncertain infinite-dimensional systems with unbounded inputs.

*IMA Journal of Mathematical Control and Information*,

*8*(2), 121-133. Abstract.

### 1990

**Ryan EP, Townley S**(1990). Non-linear systems: Robustness optimization and universal adaptive stabilization. Abstract.

**PRITCHARD AJ, TOWNLEY S**(1990). REAL STABILITY RADII FOR INFINITE DIMENSIONAL SYSTEMS. Author URL.

**HINRICHSEN D, PRITCHARD AJ, TOWNLEY SB**(1990). RICCATI EQUATION APPROACH TO MAXIMIZING THE COMPLEX STABILITY RADIUS BY STATE FEEDBACK.

*INTERNATIONAL JOURNAL OF CONTROL*,

*52*(4), 769-794. Author URL.

**Townley S**(1990). Stability radius optimization: a geometric approach.

*Systems and Control Letters*,

*14*(3), 199-207. Abstract.

### 1989

**Pritchard AJ, Townley S**(1989). Robustness of linear systems.

*Journal of Differential Equations*,

*77*(2), 254-286. Abstract.

### 1988

**Pritchard AJ, Townley S**(1988). Robust compensator design via structured stability radii.

*Systems and Control Letters*,

*11*(1), 33-37. Abstract.

### 1987

**PRITCHARD AJ, TOWNLEY S**(1987). A STABILITY RADIUS FOR INFINITE DIMENSIONAL SYSTEMS.

*LECTURE NOTES IN CONTROL AND INFORMATION SCIENCES*,

*102*, 272-291. Author URL.

**Chapman MJ, Pritchard AJ, Townley SB**(1987). Modelling linear distributed parameter systems.

*Systems Science*,

*13*(3-4), 37-50. Abstract.

**Pritchard AJ, Townley S**(1987). ROBUSTNESS OF INFINITE DIMENSIONAL SYSTEMS.

*IFAC Proceedings Series*(3), 459-462. Abstract.