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Exponential input-to-state stability for Lur’e systems via Integral Quadratic Constraints and Zames-Falb Multipliers (2024)
Journal Article
Drummond, R., Guiver, C., & Turner, M. (in press). Exponential input-to-state stability for Lur’e systems via Integral Quadratic Constraints and Zames-Falb Multipliers. IMA Journal of Mathematical Control and Information,

Absolute stability criteria which are sufficient for global exponential stability are shown, under a Lipschitz assumption, to be sufficient for the a priori stronger exponential input-to-state stability property. Important corollaries of this result... Read More about Exponential input-to-state stability for Lur’e systems via Integral Quadratic Constraints and Zames-Falb Multipliers.

The regime-conversion method: a hybrid technique for simulating well-mixed chemical reaction networks (2023)
Journal Article
Kynaston, J. C., Yates, C. A., Hekkink, A. V. F., & Guiver, C. (2023). The regime-conversion method: a hybrid technique for simulating well-mixed chemical reaction networks. Frontiers in Applied Mathematics and Statistics, 9, Article 1107441. https://doi.org/10.3389/fams.2023.1107441

There exist several methods for simulating biological and physical systems as represented by chemical reaction networks. Systems with low numbers of particles are frequently modeled as discrete-state Markov jump processes and are typically simulated... Read More about The regime-conversion method: a hybrid technique for simulating well-mixed chemical reaction networks.

Representations and Regularity of Vector-Valued Right-Shift Invariant Operators Between Half-Line Bessel Potential Spaces (2023)
Journal Article
Guiver, C., & Opmeer, M. R. (2023). Representations and Regularity of Vector-Valued Right-Shift Invariant Operators Between Half-Line Bessel Potential Spaces. Integral Equations and Operator Theory, 95(3), Article 19. https://doi.org/10.1007/s00020-023-02738-3

Representation and boundedness properties of linear, right-shift invariant operators on half-line Bessel potential spaces (also known as fractional-order Sobolev spaces) as operator-valued multiplication operators in terms of the Laplace transform ar... Read More about Representations and Regularity of Vector-Valued Right-Shift Invariant Operators Between Half-Line Bessel Potential Spaces.

Stability of Forced Higher-Order Continuous-Time Lur'e Systems: a Behavioural Input-Output Perspective (2023)
Journal Article
Guiver, C., & Logemann, H. (in press). Stability of Forced Higher-Order Continuous-Time Lur'e Systems: a Behavioural Input-Output Perspective. International Journal of Control, https://doi.org/10.1080/00207179.2023.2233023

We consider a class of forced continuous-time Lur'e systems obtained by applying nonlinear feedback to a higher-order linear differential equation which defines an input-output system in the sense of behavioural systems theory. This linear system dir... Read More about Stability of Forced Higher-Order Continuous-Time Lur'e Systems: a Behavioural Input-Output Perspective.

The exponential input-to-state stability property: characterisations and feedback connections (2023)
Journal Article
Guiver, C., & Logemann, H. (2023). The exponential input-to-state stability property: characterisations and feedback connections. Mathematics of Control, Signals, and Systems, 35(2), 375-398. https://doi.org/10.1007/s00498-023-00344-7

The exponential input-to-state stability (ISS) property is considered for systems of controlled nonlinear ordinary differential equations. A characterisation of this property is provided, including in terms of a so-called exponential ISS Lyapunov fun... Read More about The exponential input-to-state stability property: characterisations and feedback connections.

Low‐gain integral control for a class of discrete‐time Lur'e systems with applications to sampled‐data control (2022)
Journal Article
Guiver, C., Rebarber, R., & Townley, S. (2023). Low‐gain integral control for a class of discrete‐time Lur'e systems with applications to sampled‐data control. International Journal of Robust and Nonlinear Control, 33(3), 1410-1437. https://doi.org/10.1002/rnc.6455

We study low-gain (P)roportional (I)ntegral control of multivariate discrete-time, forced Lur’e systems to solve the output-tracking problem for constant reference signals. We formulate an incremental sector condition which is sufficient for a usual... Read More about Low‐gain integral control for a class of discrete‐time Lur'e systems with applications to sampled‐data control.

Aizerman Conjectures for a class of multivariate positive systems (2022)
Journal Article
Drummond, R., Guiver, C., & Turner, M. (2023). Aizerman Conjectures for a class of multivariate positive systems. IEEE Transactions on Automatic Control, 68(8), 5073 - 5080. https://doi.org/10.1109/TAC.2022.3217740

The Aizerman Conjecture predicts stability for a class of nonlinear control systems on the basis of linear system stability analysis. The conjecture is known to be false in general. Here, a number of Aizerman conjectures are shown to be true for a cl... Read More about Aizerman Conjectures for a class of multivariate positive systems.

Stabilisation by adaptive feedback control for positive difference equations with applications in pest management (2022)
Journal Article
Edholm, C., Guiver, C., Rebarber, R., Tenhumberg, B., & Townley, S. (2022). Stabilisation by adaptive feedback control for positive difference equations with applications in pest management. SIAM Journal on Control and Optimization, 60(4), 2214-2245. https://doi.org/10.1137/21m1398240

An adaptive feedback control scheme is proposed for stabilising a class of forced nonlinear positive difference equations. The adaptive scheme is based on so-called high-gain adaptive controllers, and contains substantial robustness with respect... Read More about Stabilisation by adaptive feedback control for positive difference equations with applications in pest management.

Quantifying the per-capita contribution of all components of a migratory cycle: a modelling framework (2022)
Journal Article
Smith, P., Guiver, C., & Adams, B. (2022). Quantifying the per-capita contribution of all components of a migratory cycle: a modelling framework. Ecological Modelling, 471, Article 110056. https://doi.org/10.1016/j.ecolmodel.2022.110056

Migratory species make use of different habitats and pathways at different life stages, and in different seasons. Ecological management strategies proposed for migratory species should acknowledge the importance of each component of the migratory cyc... Read More about Quantifying the per-capita contribution of all components of a migratory cycle: a modelling framework.

An equivalence framework for an age-structured multi-stage representation of the cell cycle (2022)
Journal Article
Kynaston, J. C., Guiver, C., & Yates, C. A. (2022). An equivalence framework for an age-structured multi-stage representation of the cell cycle. Physical Review E, 105(6), https://doi.org/10.1103/PhysRevE.105.064411

We develop theoretical equivalences between stochastic and deterministic models for populations of individual cells stratified by age. Specifically, we develop a hierarchical system of equations describing the full dynamics of an age-structured multi... Read More about An equivalence framework for an age-structured multi-stage representation of the cell cycle.

The circle criterion for a class of sector-bounded dynamic nonlinearities (2022)
Journal Article
Guiver, C., & Logemann, H. (2022). The circle criterion for a class of sector-bounded dynamic nonlinearities. Mathematics of Control, Signals, and Systems, 34, 461-492. https://doi.org/10.1007/s00498-022-00324-3

We present a circle criterion which is necessary and sufficient for absolute stability with respect to a natural class of sector-bounded nonlinear causal operators. This generalized circle criterion contains the classical result as a special case. F... Read More about The circle criterion for a class of sector-bounded dynamic nonlinearities.

Incremental input-to-state stability for Lur’e systems and asymptotic behaviour in the presence of Stepanov almost periodic forcing (2021)
Journal Article
Gilmore, M., Guiver, C., & Logemann, H. (2021). Incremental input-to-state stability for Lur’e systems and asymptotic behaviour in the presence of Stepanov almost periodic forcing. Journal of Differential Equations, 300, 692-733. https://doi.org/10.1016/j.jde.2021.08.009

We prove (integral) input-to-state stability results for a class of forced Lur’e differential inclusions and use them to investigate incremental (integral) input-to-state stability properties of Lur’e differential equations. The latter provide a basi... Read More about Incremental input-to-state stability for Lur’e systems and asymptotic behaviour in the presence of Stepanov almost periodic forcing.

Persistence and stability for a class of forced positive nonlinear delay-differential systems (2021)
Journal Article
Franco, D., Guiver, C., & Logemann, H. (2021). Persistence and stability for a class of forced positive nonlinear delay-differential systems. Acta applicandae mathematicae, 174(1), Article 1 (2021). https://doi.org/10.1007/s10440-021-00414-5

Persistence and stability properties are considered for a class of forced positive non-linear delay-differential systems which arise in mathematical ecology and other applied contexts.The inclusion of forcing incorporates the effects of control actio... Read More about Persistence and stability for a class of forced positive nonlinear delay-differential systems.

A switching feedback control approach for persistence of managed resources (2021)
Journal Article
Franco, D., Guiver, C., Smith, P., & Townley, S. (2022). A switching feedback control approach for persistence of managed resources. Discrete and Continuous Dynamical Systems - Series B, 27(3), 1765-1787. https://doi.org/10.3934/dcdsb.2021109

An adaptive switching feedback control scheme is proposed for classes of discrete-time, positive difference equations, or systems of equations. In overview, the objective is to choose a control strategy which ensures persistence of the state, consequ... Read More about A switching feedback control approach for persistence of managed resources.

Sampled-data integral control of multivariable linear infinite-dimensional systems with input nonlinearities (2021)
Journal Article
Gilmore, M. E., Guiver, C., & Logemann, H. (2022). Sampled-data integral control of multivariable linear infinite-dimensional systems with input nonlinearities. Mathematical Control and Related Fields, 12(1), 17-47. https://doi.org/10.3934/mcrf.2021001

A low-gain integral controller with anti-windup component is presented for exponentially stable, linear, discrete-time, infinite-dimensional control systems subject to input nonlinearities and external disturbances. We derive a disturbance-to-state... Read More about Sampled-data integral control of multivariable linear infinite-dimensional systems with input nonlinearities.

Dynamic observers for unknown populations (2020)
Journal Article
Guiver, C., Poppelreiter, N., Rebarber, R., Tenhumberg, B., & Townley, S. (2021). Dynamic observers for unknown populations. Discrete and Continuous Dynamical Systems - Series B, 26(6), 3279-3302. https://doi.org/10.3934/dcdsb.2020232

Dynamic observers are considered in the context of structured population modeling and management. Roughly, observers combine a known measured variable of some process with a model of that process to asymptotically reconstruct the unknown state variab... Read More about Dynamic observers for unknown populations.

On the global attractor of delay differential equations with unimodal feedback not satisfying the negative Schwarzian derivative condition (2020)
Journal Article
Franco, D., Guiver, C., Logemann, H., & Perán, J. (2020). On the global attractor of delay differential equations with unimodal feedback not satisfying the negative Schwarzian derivative condition. Electronic Journal of Qualitative Theory of Differential Equations, 1-15. https://doi.org/10.14232/ejqtde.2020.1.76

We study the size of the global attractor for a delay differential equation with unimodal feedback. We are interested in extending and complementing a dichotomy result by Liz and Röst, which assumed that the Schwarzian derivative of the nonlinear fee... Read More about On the global attractor of delay differential equations with unimodal feedback not satisfying the negative Schwarzian derivative condition.

Infinite-dimensional Lur'e systems with almost periodic forcing (2020)
Journal Article
Gilmore, M. E., Guiver, C., & Logemann, H. (2020). Infinite-dimensional Lur'e systems with almost periodic forcing. Mathematics of Control, Signals, and Systems, 32, 327-360. https://doi.org/10.1007/s00498-020-00262-y

We consider forced Lur’e systems in which the linear dynamic component is an infinite-dimensional well-posed system. Numerous physically motivated delay- and partial-differential equa-tions are known to belong to this class of infinite-dime... Read More about Infinite-dimensional Lur'e systems with almost periodic forcing.

Semi-global incremental input-to-state stability of discrete-time Lur'e systems (2020)
Journal Article
Gilmore, M., Guiver, C., & Logemann, H. (2020). Semi-global incremental input-to-state stability of discrete-time Lur'e systems. Systems and Control Letters, 136, Article 104593. https://doi.org/10.1016/j.sysconle.2019.104593

We present sufficient conditions for semi-global incremental input-to-state stability of a class of forced discrete-time Lur'e systems. The results derived are reminiscent of well-known absolute stability criteria such as the small gain theorem and t... Read More about Semi-global incremental input-to-state stability of discrete-time Lur'e systems.

A circle criterion for strong integral input-to-state stability (2019)
Journal Article
Guiver, C., & Logemann, H. (2020). A circle criterion for strong integral input-to-state stability. Automatica, 111, Article 108641. https://doi.org/10.1016/j.automatica.2019.108641

We present sufficient conditions for integral input-to-state stability (iISS) and strong iISS of the zero equilibrium pair of continuous-time forced Lur'e systems, where by strong iISS we mean the conjunction of iISS and small-signal ISS. Our main re... Read More about A circle criterion for strong integral input-to-state stability.

Boundedness, persistence and stability for classes of forced difference equations arising in population ecology (2019)
Journal Article
Franco, D., Guiver, C., Logemann, H., & Perán, J. (2019). Boundedness, persistence and stability for classes of forced difference equations arising in population ecology. Journal of Mathematical Biology, 79, 1029-1076. https://doi.org/10.1007/s00285-019-01388-7

Boundedness, persistence and stability properties are considered for a class of nonlinear, possibly infinite-dimensional, forced difference equations which arise in a number of ecological and biological contexts. The inclusion of forcing incorporates... Read More about Boundedness, persistence and stability for classes of forced difference equations arising in population ecology.

Stability and convergence properties of forced infinite-dimensional discrete-time Lur'e systems (2019)
Journal Article
Gilmore, M. E., Guiver, C., & Logemann, H. (2020). Stability and convergence properties of forced infinite-dimensional discrete-time Lur'e systems. International Journal of Control, 93(12), 3026-3049. https://doi.org/10.1080/00207179.2019.1575528

Incremental stability and convergence properties for forced, infinite-dimensional, discrete-time Lur'e systems are addressed. Lur'e systems have a linear and nonlinear component and arise as the feedback interconnection of a linear control system and... Read More about Stability and convergence properties of forced infinite-dimensional discrete-time Lur'e systems.

Infinite-dimensional Lur'e systems: input-to-state stability and convergence properties (2019)
Journal Article
Guiver, C., Logemann, H., & Opmeer, M. R. (2019). Infinite-dimensional Lur'e systems: input-to-state stability and convergence properties. SIAM Journal on Control and Optimization, 57(1), 334-365. https://doi.org/10.1137/17M1150426

We consider forced Lur'e systems in which the linear dynamic component is an infinite-dimensional well-posed system. Numerous physically motivated delay- and partial differential equations are known to belong to this class of infinite-dimensional sys... Read More about Infinite-dimensional Lur'e systems: input-to-state stability and convergence properties.

The generalised singular perturbation approximation for bounded real and positive real control systems (2018)
Journal Article
Guiver, C. (2019). The generalised singular perturbation approximation for bounded real and positive real control systems. Mathematical Control and Related Fields, 9(2), 313-350. https://doi.org/10.3934/mcrf.2019016

The generalised singular perturbation approximation (GSPA) is considered as a model reduction scheme for bounded real and positive real linear control systems. The GSPA is a state-space approach to truncation with the defining property that the trans... Read More about The generalised singular perturbation approximation for bounded real and positive real control systems.

Recent Findings on Strong Integral Input-To-State Stability for Forced Lur'e Systems (2018)
Presentation / Conference
Guiver, C., & Logemann, H. (2018, September). Recent Findings on Strong Integral Input-To-State Stability for Forced Lur'e Systems. Paper presented at UKACC 12th International Conference on Control (CONTROL), Sheffield, UK

We would like to present recent theoretical results on the strong integral Input-to-State Stability (strong iISS) for the following class of finite-dimensional, continuous-time forced Lur'e systems.

Small-gain stability theorems for positive Lur'e inclusions (2018)
Journal Article
Guiver, C., Logemann, H., & Rüffer, B. (2019). Small-gain stability theorems for positive Lur'e inclusions. Positivity, 23, 249-289. https://doi.org/10.1007/s11117-018-0605-2

Stability results are presented for a class of differential and difference inclusions, so-called positive Lur{\textquoteright}e inclusions which arise, for example, as the feedback interconnection of a linear positive system with a positive set-valued... Read More about Small-gain stability theorems for positive Lur'e inclusions.

Management of Invasive Insect Species using Optimal Control Theory (2018)
Journal Article
Edholm, C., 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. https://doi.org/10.1016/j.ecolmodel.2018.04.011

We discuss the use of optimal control theory to determine the most cost-effective management strategies for insect pests. We use a stage-structured linear population projection model where the modeled control action increases the mortality in one of... Read More about Management of Invasive Insect Species using Optimal Control Theory.

On the strict monotonicity of spectral radii for classes of bounded positive linear operators (2018)
Journal Article
Guiver, C. (2018). On the strict monotonicity of spectral radii for classes of bounded positive linear operators. Positivity, 22, 1173-1190. https://doi.org/10.1007/s11117-018-0566-5

Strict monotonicity of the spectral radii of bounded, positive, ordered linear operators is investigated. It is well-known that under reasonable assumptions, the spectral radii of two ordered positive operators enjoy a non-strict inequality. It is al... Read More about On the strict monotonicity of spectral radii for classes of bounded positive linear operators.

Transfer Functions of Infinite-Dimensional Systems: Positive Realness and Stabilization (2017)
Journal Article
Guiver, C., Logemann, H., & Opmeer, M. R. (2017). Transfer Functions of Infinite-Dimensional Systems: Positive Realness and Stabilization. Mathematics of Control, Signals, and Systems, 29, Article 20 (2017). https://doi.org/10.1007/s00498-017-0203-z

We consider a general class of operator-valued irrational positive-real functions with an emphasis on their frequency-domain properties and the relation with stabilization by output feedback. Such functions arise naturally as the transfer functions o... Read More about Transfer Functions of Infinite-Dimensional Systems: Positive Realness and Stabilization.

Semi-Global Persistence and Stability for a Class of Forced Discrete-Time Population Models (2017)
Journal Article
Franco, D., Guiver, C., Logemann, H., & Perán, J. (2017). Semi-Global Persistence and Stability for a Class of Forced Discrete-Time Population Models. Physica D: Nonlinear Phenomena, 360, 46-61. https://doi.org/10.1016/j.physd.2017.08.001

We consider persistence and stability properties for a class of forced discrete-time difference equations with three defining properties: the solution is constrained to evolve in the non-negative orthant, the forcing acts multiplicatively, and the dy... Read More about Semi-Global Persistence and Stability for a Class of Forced Discrete-Time Population Models.

Low-gain Integral Control for Multi-Input, Multi-Output Linear Systems with Input Nonlinearities (2017)
Journal Article
Guiver, C., Logemann, H., & Townley, S. (2017). Low-gain Integral Control for Multi-Input, Multi-Output Linear Systems with Input Nonlinearities. IEEE Transactions on Automatic Control, 62(9), 4776-4783. https://doi.org/10.1109/TAC.2017.2691301

We consider the inclusion of a static anti-windup component in a continuous-time low-gain integral controller in feedback with a multi-input multi-output stable linear system subject to an input nonlinearity (from a class of functions that includes c... Read More about Low-gain Integral Control for Multi-Input, Multi-Output Linear Systems with Input Nonlinearities.

A necessary condition for dispersal driven growth of populations with discrete patch dynamics (2017)
Journal Article
Guiver, C., Packman, D., & Townley, S. (2017). A necessary condition for dispersal driven growth of populations with discrete patch dynamics. Journal of Theoretical Biology, 424, 11-25. https://doi.org/10.1016/j.jtbi.2017.03.030

We revisit the question of when can dispersal-induced coupling between discrete sink populations cause overall population growth? Such a phenomenon is called dispersal driven growth and provides a simple explanation of how dispersal can allow populat... Read More about A necessary condition for dispersal driven growth of populations with discrete patch dynamics.

The converging-input converging-state property for Lur’e systems (2017)
Journal Article
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, Article 4 (2017). https://doi.org/10.1007/s00498-016-0184-3

Using methods from classical absolute stability theory, combined with recent results on input-to-state stability (ISS) of Lur{\textquoteright}e systems, we derive necessary and sufficient conditions for a class of Lur{\textquoteright}e systems to hav... Read More about The converging-input converging-state property for Lur’e systems.

A note on the eigenvectors of perturbed matrices with applications to linear positive systems (2016)
Journal Article
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. https://doi.org/10.1016/j.laa.2016.07.010

A result is presented describing the eigenvectors of a perturbed matrix, for a class of structured perturbations. One motivation for doing so is that positive eigenvectors of nonnegative, irreducible matrices are known to induce norms — acting much l... Read More about A note on the eigenvectors of perturbed matrices with applications to linear positive systems.

Stability of Non-Negative Lur'e Systems (2016)
Journal Article
Bill, A., Guiver, C., Logemann, H., & Townley, S. (2016). Stability of Non-Negative Lur'e Systems. SIAM Journal on Control and Optimization, 54(3), 1176-1211. https://doi.org/10.1137/140994599

A stability/instability trichotomy for a class of nonnegative continuous-time Lur'e systems is derived. Asymptotic, exponential, and input-to-state stability concepts are considered. The presented trichotomy rests on Perron–Frobenius theory, absolute... Read More about Stability of Non-Negative Lur'e Systems.

Simple adaptive control for positive linear systems with applications to pest management (2016)
Journal Article
Guiver, C., Edholm, C., Jin, Y., Mueller, M., Powell, J., Rebarber, R., …Townley, S. (2016). Simple adaptive control for positive linear systems with applications to pest management. SIAM Journal on Applied Mathematics, 76(1), 238-275. https://doi.org/10.1137/140996926

Pest management is vitally important for modern arable farming, but models for pest species are often highly uncertain. In the context of pest management, control actions are naturally described by a nonlinear feedback that is generally unknown, whic... Read More about Simple adaptive control for positive linear systems with applications to pest management.

Robust set-point regulation for ecological models with multiple management goals (2015)
Journal Article
Guiver, C., Mueller, M., Hodgson, D., & Townley, S. (2016). Robust set-point regulation for ecological models with multiple management goals. Journal of Mathematical Biology, 72, 1467-1529. https://doi.org/10.1007/s00285-015-0919-7

Population managers will often have to deal with problems of meeting multiple goals, for example, keeping at specific levels both the total population and population abundances in given stage-classes of a stratified population. In control engineering... Read More about Robust set-point regulation for ecological models with multiple management goals.

The role of population inertia in predicting the outcome of stage-structured biological invasions (2015)
Journal Article
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. Mathematical Biosciences, 265, 1-11. https://doi.org/10.1016/j.mbs.2015.04.005

Deterministic dynamic models for coupled resident and invader populations are considered with the purpose of finding quantities that are effective at predicting when the invasive population will become established asymptotically. A key feature of the... Read More about The role of population inertia in predicting the outcome of stage-structured biological invasions.

Bounds on the dynamics of sink populations with noisy immigration (2014)
Journal Article
Eager, E. A., Guiver, C., Hodgson, D., Rebarber, R., Stott, I., & Townley, S. (2014). Bounds on the dynamics of sink populations with noisy immigration. Theoretical Population Biology, 92, 88-96. https://doi.org/10.1016/j.tpb.2013.12.004

Sink populations are doomed to decline to extinction in the absence of immigration. The dynamics of sink populations are not easily modelled using the standard framework of per capita rates of immigration, because numbers of immigrants are determined... Read More about Bounds on the dynamics of sink populations with noisy immigration.

A stability/instability trichotomy for non-negative Lur'e systems (2014)
Conference Proceeding
Bill, A., Guiver, C., Logemann, H., & Townley, S. (2014). A stability/instability trichotomy for non-negative Lur'e systems. In Proceedings of the 21st International Symposium on Mathematical Theory of Networks and Systems (1752-1754)

We identify a stability/instability trichotomy for a class of non-negative continuous-time Lur'e systems. Asymptotic as well as input-to-state stability concepts (ISS) are considered. The presented trichotomy rests on Perron-Frobenius theory, absolut... Read More about A stability/instability trichotomy for non-negative Lur'e systems.

Controllability for positive discrete–time linear systems with positive state (2014)
Conference Proceeding
Guiver, C., & Townley, S. (2014). Controllability for positive discrete–time linear systems with positive state. In Proceedings of the 21st International Symposium on Mathematical Theory of Networks and Systems (1387-1394)

Controllability of componentwise nonnegative discrete-time linear systems is considered. The key difference here from the well-established positive systems theory is that we permit the case where the input takes negative values, provided that the sta... Read More about Controllability for positive discrete–time linear systems with positive state.

Integral control for population management (2014)
Journal Article
Guiver, C., Logemann, H., Rebarber, R., Bill, A., Tenhumberg, B., Hodgson, D., & Townley, S. (2015). Integral control for population management. Journal of Mathematical Biology, 70, 1015-1063. https://doi.org/10.1007/s00285-014-0789-4

We present a novel management methodology for restocking a declining population. The strategy uses integral control, a concept ubiquitous in control theory which has not been applied to population dynamics. Integral control is based on dynamic feedba... Read More about Integral control for population management.

Model reduction by balanced truncation for systems with nuclear Hankel operators (2014)
Journal Article
Guiver, C., & Opmeer, M. R. (2014). Model reduction by balanced truncation for systems with nuclear Hankel operators. SIAM Journal on Control and Optimization, 52(2), 1366-1401. https://doi.org/10.1137/110846981

We prove the H-infinity error bounds for Lyapunov balanced truncation and for optimal Hankel norm approximation under the assumption that the Hankel operator is nuclear. This is an improvement of the result from Glover, Curtain, and Partington [SIAM... Read More about Model reduction by balanced truncation for systems with nuclear Hankel operators.

Positive state controllability of positive linear systems (2014)
Journal Article
Guiver, C., Hodgson, D., & Townley, S. (2014). Positive state controllability of positive linear systems. Systems and Control Letters, 65, 23-29. https://doi.org/10.1016/j.sysconle.2013.12.002

Controllability of positive systems by positive inputs arises naturally in applications where both external and internal variables must remain positive for all time. In many applications, particularly in population biology, the need for positive inpu... Read More about Positive state controllability of positive linear systems.

Error bounds in the gap metric for dissipative balanced approximations (2013)
Journal Article
Guiver, C., & Opmeer, M. R. (2013). Error bounds in the gap metric for dissipative balanced approximations. Linear Algebra and its Applications, 439(12), 3659-3698. https://doi.org/10.1016/j.laa.2013.09.032

We derive an error bound in the gap metric for positive real balanced truncation and positive real singular perturbation approximation. We prove these results by working in the context of dissipative driving-variable systems, as in behavioral and sta... Read More about Error bounds in the gap metric for dissipative balanced approximations.

Bounded real and positive real balanced truncation for infinite-dimensional systems (2013)
Journal Article
Guiver, C., & Opmeer, M. R. (2013). Bounded real and positive real balanced truncation for infinite-dimensional systems. Mathematical Control and Related Fields, 3(1), 83-119. https://doi.org/10.3934/mcrf.2013.3.83

Bounded real balanced truncation for infinite-dimensional systems is considered. This provides reduced order finite-dimensional systems that retain bounded realness. We obtain an error bound analogous to the finite-dimensional case in terms of the bo... Read More about Bounded real and positive real balanced truncation for infinite-dimensional systems.

A counter-example to “Positive realness preserving model reduction with H-\infty norm error bounds” (2011)
Journal Article
Guiver, C., & Opmeer, M. R. (2011). A counter-example to “Positive realness preserving model reduction with H-\infty norm error bounds”. IEEE Transactions on Circuits and Systems I: Regular Papers, 58(6), 1410-1411. https://doi.org/10.1109/tcsi.2010.2097750

We provide a counter example to the H∞ error bound for the difference of a positive real transfer function and its positive real balanced truncation stated in “Positive realness preserving model reduction with H-\infty norm error bounds” IEEE Trans.... Read More about A counter-example to “Positive realness preserving model reduction with H-\infty norm error bounds”.

Non-dissipative boundary feedback for elastic beams (2010)
Conference Proceeding
Guiver, C., & Opmeer, M. R. (2010). Non-dissipative boundary feedback for elastic beams. In Proceedings of the 19th International Symposium on Mathematical Theory of Networks and Systems - MTNS 2010

We show that a non-dissipative feedback that has been shown in the literature to exponentially stabilize an Euler-Bernoulli beam makes a Rayleigh beam and a Timoshenkobeam unstable.