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Convex neural network synthesis for robustness in the 1-norm (2024)
Presentation / Conference Contribution
Drummond, R., Guiver, C., & Turner, M. C. (2024, July). Convex neural network synthesis for robustness in the 1-norm. Presented at 6th Annual Learning for Dynamics & Control Conference, Oxford, England

With neural networks being used to control safety-critical systems, they increasingly have to be both accurate (in the sense of matching inputs to outputs) and robust. However, these two properties are often at odds with each other and a trade-off ha... Read More about Convex neural network synthesis for robustness in the 1-norm.

Regularity and Compactness Properties of Integral Hankel Operators and Their Singular Vectors (2024)
Journal Article
Guiver, C. (2024). Regularity and Compactness Properties of Integral Hankel Operators and Their Singular Vectors. Complex Analysis and Operator Theory, 19, Article 6. https://doi.org/10.1007/s11785-024-01627-w

Integral Hankel operators on vector-valued $L^2(\mathbb{R}_+,U)$-function spaces are considered. Regularity (integrability) and compactness properties of the kernel are shown to give rise to quantifiable regularity and compactness properties of the H... Read More about Regularity and Compactness Properties of Integral Hankel Operators and Their Singular Vectors.

Quantifying the impact of environmental changes on migratory species: a model perturbation framework (2024)
Journal Article
Smith, P., Adams, B., & Guiver, C. (2024). Quantifying the impact of environmental changes on migratory species: a model perturbation framework. Frontiers in Ecology and Evolution, 12, Article 1426018. https://doi.org/10.3389/fevo.2024.1426018

Migratory species use different habitats and pathways across their migratory route. Pathway contribution metrics are transient metrics of population growth, derived from population models, and quantify the predicted contribution of an individual, tra... Read More about Quantifying the impact of environmental changes on migratory species: a model perturbation framework.

A mixed passivity/small-gain theorem for Sobolev input-output stability (2024)
Journal Article
Guiver, C., Logemann, H., & Opmeer, M. R. (2024). A mixed passivity/small-gain theorem for Sobolev input-output stability. SIAM Journal on Control and Optimization, 62(6), 3042-3075. https://doi.org/10.1137/24M1643128

A stability theorem for the feedback connection of two (possibly infinite-dimensional) time-invariant linear systems is presented. The theorem is formulated in the frequency domain and is in the spirit of combined passivity/small-gain results. It pla... Read More about A mixed passivity/small-gain theorem for Sobolev input-output stability.

A linear dissipativity approach to incremental input-to-state stability for a class of positive Lur’e systems (2024)
Journal Article
Piengeon, V., & Guiver, C. (online). A linear dissipativity approach to incremental input-to-state stability for a class of positive Lur’e systems. International Journal of Control, https://doi.org/10.1080/00207179.2024.2403473

Incremental stability properties are considered for certain systems of forced, nonlinear differential equations with a particular positivity structure. An incremental stability estimate is derived for pairs of input/state/output trajectories of the L... Read More about A linear dissipativity approach to incremental input-to-state stability for a class of positive Lur’e systems.

A method for constrained energy-maximising control of heaving wave-energy converters via a nonlinear frequency response (2024)
Presentation / Conference Contribution
Guiver, C. (2024, August). A method for constrained energy-maximising control of heaving wave-energy converters via a nonlinear frequency response. Presented at The 8th IEEE Conference on Control Technology and Applications (CCTA) 2024, Newcastle Upon Tyne

A theoretical grounding is presented for justifying how frequency domain methods may be applied in the determination of constrained extracted-energy maximising controls in wave-energy conversion applications subject to nonlinear models. A computation... Read More about A method for constrained energy-maximising control of heaving wave-energy converters via a nonlinear frequency response.

Persistency and stability of a class of nonlinear forced positive discrete-time systems with delays (2024)
Journal Article
Franco, D., Guiver, C., Logemann, H., & Perán, J. (2024). Persistency and stability of a class of nonlinear forced positive discrete-time systems with delays. Physica D: Nonlinear Phenomena, 467, Article 134260. https://doi.org/10.1016/j.physd.2024.134260

Persistence, excitability and stability properties are considered for a class of nonlinear, forced, positive discrete-time systems with delays. As will be illustrated, these equations arise in a number of biological and ecological contexts. Novel suf... Read More about Persistency and stability of a class of nonlinear forced positive discrete-time systems with delays.

The energy-balance method for optimal control in renewable energy applications (2024)
Journal Article
Guiver, C., & Opmeer, M. R. (2024). The energy-balance method for optimal control in renewable energy applications. Renewable Energy Focus, 50, Article 100582. https://doi.org/10.1016/j.ref.2024.100582

A theoretical method is presented, called the energy-balance method, for maximising the energy extracted from a renewable energy converter in terms of determination of an optimal control. The method applies to control systems specified by linear grap... Read More about The energy-balance method for optimal control in renewable energy applications.

Operator-valued multiplier theorems for causal translation-invariant operators with applications to control theoretic input-output stability (2024)
Journal Article
Guiver, C., Logemann, H., & Opmeer, M. R. (2024). Operator-valued multiplier theorems for causal translation-invariant operators with applications to control theoretic input-output stability. Mathematics of Control, Signals, and Systems, 36(4), 729-773. https://doi.org/10.1007/s00498-024-00387-4

We prove an operator-valued Laplace multiplier theorem for causal translation-invariant linear operators which provides a characterization of continuity from Hα(R, U) to Hβ(R, U) (fractional U-valued Sobolev spaces, U a complex Hilbert space) in term... Read More about Operator-valued multiplier theorems for causal translation-invariant operators with applications to control theoretic input-output stability.

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. (2024). Exponential input-to-state stability for Lur’e systems via Integral Quadratic Constraints and Zames-Falb Multipliers. IMA Journal of Mathematical Control and Information, 41(1), 1-17. https://doi.org/10.1093/imamci/dnae003

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. (2024). Stability of Forced Higher-Order Continuous-Time Lur'e Systems: a Behavioural Input-Output Perspective. International Journal of Control, 97(8), 1788-1809. 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.