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Evolution of plastic learning in spiking networks via memristive connections (2012)
Journal Article
Howard, G., Howard, D., Gale, E., Bull, L., De Lacy Costello, B., & Adamatzky, A. (2012). Evolution of plastic learning in spiking networks via memristive connections. IEEE Transactions on Evolutionary Computation, 16(5), 711-729. https://doi.org/10.1109/TEVC.2011.2170199

This paper presents a spiking neuroevolutionary system which implements memristors as plastic connections, i.e., whose weights can vary during a trial. The evolutionary design process exploits parameter self-adaptation and variable topologies, allowi... Read More about Evolution of plastic learning in spiking networks via memristive connections.

On architectures of circuits implemented in simulated Belousov-Zhabotinsky droplets (2012)
Journal Article
Adamatzky, A., Holley, J., Dittrich, P., Gorecki, J., De Lacy Costello, B., Zauner, K. P., & Bull, L. (2012). On architectures of circuits implemented in simulated Belousov-Zhabotinsky droplets. BioSystems, 109(1), 72-77. https://doi.org/10.1016/j.biosystems.2011.12.007

When lipid vesicles filled with Belousov-Zhabotinsky (BZ) excitable chemical medium are packed in tight assembles, waves of excitation may travel between the vesicles. When several waves meet in a vesicle some fragments may deflect, others can annihi... Read More about On architectures of circuits implemented in simulated Belousov-Zhabotinsky droplets.

Logical and arithmetic circuits in Belousov-Zhabotinsky encapsulated disks (2011)
Journal Article
Holley, J., Jahan, I., De Lacy Costello, B., Bull, L., & Adamatzky, A. (2011). Logical and arithmetic circuits in Belousov-Zhabotinsky encapsulated disks. Physical Review E, 84(5), 056110. https://doi.org/10.1103/PhysRevE.84.056110

Excitation waves on a subexcitable Belousov-Zhabotinsky (BZ) substrate can be manipulated by chemical variations in the substrate and by interactions with other waves. Symbolic assignment and interpretation of wave dynamics can be used to perform log... Read More about Logical and arithmetic circuits in Belousov-Zhabotinsky encapsulated disks.

On computing in fine-grained compartmentalised Belousov-Zhabotinsky medium (2011)
Journal Article
Adamatzky, A., Holley, J., Bull, L., & De Lacy Costello, B. (2011). On computing in fine-grained compartmentalised Belousov-Zhabotinsky medium. Chaos, Solitons and Fractals, 44(10), 779-790. https://doi.org/10.1016/j.chaos.2011.03.010

We introduce results of computer experiments on information processing in a hexagonal array of vesicles filled with Belousov-Zhabotinsky (BZ) solution in a sub-excitable mode. We represent values of Boolean variables by excitation wave-fragments and... Read More about On computing in fine-grained compartmentalised Belousov-Zhabotinsky medium.

Vesicle computers: Approximating a Voronoi diagram using Voronoi automata (2011)
Journal Article
Adamatzky, A., De Lacy Costello, B., Holley, J., Gorecki, J., & Bull, L. (2011). Vesicle computers: Approximating a Voronoi diagram using Voronoi automata. Chaos, Solitons and Fractals, 44(7), 480-489. https://doi.org/10.1016/j.chaos.2011.01.016

Irregular arrangements of vesicles filled with excitable and precipitating chemical systems are imitated by Voronoi automata - finite-state machines defined on a planar Voronoi diagram. Every Voronoi cell takes four states: resting, excited, refracto... Read More about Vesicle computers: Approximating a Voronoi diagram using Voronoi automata.

Computational modalities of Belousov-Zhabotinsky encapsulated vesicles (2011)
Journal Article
Holley, J., Adamatzky, A., Bull, L., De Lacy Costello, B., & Jahan, I. (2011). Computational modalities of Belousov-Zhabotinsky encapsulated vesicles. Nano Communication Networks, 2(1), 50-61. https://doi.org/10.1016/j.nancom.2011.02.002

We present both simulated and partial empirical evidences for the computational utility of many connected vesicle analogues of an encapsulated nonlinear chemical processing medium. By connecting small vesicles containing a solution of sub-excitable B... Read More about Computational modalities of Belousov-Zhabotinsky encapsulated vesicles.

On polymorphic logical gates in subexcitable chemical medium (2011)
Journal Article
Adamatzky, A., De Lacy Costello, B., & Bull, L. (2011). On polymorphic logical gates in subexcitable chemical medium. International Journal of Bifurcation and Chaos, 21(07), 1977-1986. https://doi.org/10.1142/S0218127411029574

In a subexcitable light-sensitive Belousov-Zhabotinsky (BZ) chemical medium an asymmetric disturbance causes the formation of localized traveling wave-fragments. Under the right conditions these wave-fragments can conserve their shape and velocity ve... Read More about On polymorphic logical gates in subexcitable chemical medium.

Towards arithmetic circuits in sub-excitable chemical media (2011)
Journal Article
Adamatzky, A., De Lacy Costello, B., Bull, L., & Holley, J. (2011). Towards arithmetic circuits in sub-excitable chemical media. Israel Journal of Chemistry, 51(1), 56-66. https://doi.org/10.1002/ijch.201000046

A sub-excitable Belousov-Zhabotinsky medium exhibits localized travelling excitations (in contrast to an excitable medium exhibiting target or spiral waves). Initially assymetric perturbations give birth to excitation wave-fragments. The shape and ve... Read More about Towards arithmetic circuits in sub-excitable chemical media.

Experimental validation of binary collisions between wave fragments in the photosensitive Belousov–Zhabotinsky reaction (2009)
Journal Article
Toth, R., Stone, C., Adamatzky, A., de Lacy Costello, B., & Bull, L. (2009). Experimental validation of binary collisions between wave fragments in the photosensitive Belousov–Zhabotinsky reaction. Chaos, Solitons and Fractals, 41(4), 1605-1615. https://doi.org/10.1016/j.chaos.2008.07.001

Using the examples of an excitable chemical system (the Belousov–Zhabotinsky medium) and plasmodium of Physarum polycephalum we show that universal computation in a geometrically unconstrained medium is only possible when resources (excitability or c... Read More about Experimental validation of binary collisions between wave fragments in the photosensitive Belousov–Zhabotinsky reaction.

Experimental validation of binary collisions between wave fragments in the photosensitive Belousov-Zhabotinsky reaction (2009)
Journal Article
Toth, R., Stone, C., Adamatzky, A., de Lacy Costello, B., & Bull, L. (2009). Experimental validation of binary collisions between wave fragments in the photosensitive Belousov-Zhabotinsky reaction. Chaos, Solitons and Fractals, 41(4), 1605-1615. https://doi.org/10.1016/j.chaos.2008.07.001

We present experimental verification of wave fragment collisions in the sub-excitable Belousov-Zhabotinsky medium observed previously in simulation [Adamatzky A, De Lacy Costello B. Binary collisions between wave fragments in a sub-excitable Belousov... Read More about Experimental validation of binary collisions between wave fragments in the photosensitive Belousov-Zhabotinsky reaction.

Spiral formation and degeneration in heterogeneous excitable media (2009)
Journal Article
Toth, R., De Lacy Costello, B., Stone, C., Masere, J., Adamatzky, A., & Bull, L. (2009). Spiral formation and degeneration in heterogeneous excitable media. Physical Review E, 79(3), 035101(R) (4 pages). https://doi.org/10.1103/PhysRevE.79.035101

Spontaneous spiral formation occurs when an excitation wave is input to a heterogeneous network of low- and high-light-intensity cells projected onto a light-sensitive Belousov-Zhabotinsky reaction. The range of network conditions where spirals form... Read More about Spiral formation and degeneration in heterogeneous excitable media.

Implementation of glider guns in the light-sensitive Belousov-Zhabotinsky medium (2009)
Journal Article
De Lacy Costello, B., Toth, R., Stone, C., Adamatzky, A., & Bull, L. (2009). Implementation of glider guns in the light-sensitive Belousov-Zhabotinsky medium. Physical Review E, 79(2), 026114. https://doi.org/10.1103/PhysRevE.79.026114

In cellular automata models a glider gun is an oscillating pattern of nonquiescent states that periodically emits traveling localizations (gliders). The glider streams can be combined to construct functionally complete systems of logical gates and th... Read More about Implementation of glider guns in the light-sensitive Belousov-Zhabotinsky medium.

Dynamic control and information processing in the Belousov-Zhabotinsky reaction using a coevolutionary algorithm (2008)
Journal Article
Toth, R., Stone, C., Adamatzky, A., De Lacy Costello, B., & Bull, L. (2008). Dynamic control and information processing in the Belousov-Zhabotinsky reaction using a coevolutionary algorithm. Journal of Chemical Physics, 129(18), 184708. https://doi.org/10.1063/1.2932252

We propose that the behavior of nonlinear media can be controlled dynamically through coevolutionary systems. In this study, a light-sensitive subexcitable Belousov-Zhabotinsky reaction is controlled using a heterogeneous cellular automaton. A checke... Read More about Dynamic control and information processing in the Belousov-Zhabotinsky reaction using a coevolutionary algorithm.

Towards unconventional computing through simulated evolution: Control of nonlinear media by a learning classifier system (2008)
Journal Article
Bull, L., Budd, A., Stone, C., Uroukov, I., Costello, B. D. L., & Adamatzky, A. (2008). Towards unconventional computing through simulated evolution: Control of nonlinear media by a learning classifier system. Artificial Life, 14(2), 203-222. https://doi.org/10.1162/artl.2008.14.2.203

We propose that the behavior of nonlinear media can be controlled automatically through evolutionary learning. By extension, forms of unconventional computing (viz., massively parallel nonlinear computers) can be realized by such an approach. In this... Read More about Towards unconventional computing through simulated evolution: Control of nonlinear media by a learning classifier system.

Initial results from the use of evolutionary learning to control chemical computers (2008)
Journal Article
Budd, A., Stone, C., Masere, J., Adamatzky, A., de Lacy Costello, B., & Bull, L. (2008). Initial results from the use of evolutionary learning to control chemical computers. International Journal of Unconventional Computing, 4(1), 13-22

The behaviour of pulses of Belousov-Zhabotinski (BZ) reaction diffusion waves can be controlled automatically through machine learning. By extension, a form of chemical network computing, i.e., a massively parallel non-linear Computer, can be realise... Read More about Initial results from the use of evolutionary learning to control chemical computers.