Searcharxiv⌕ Search

arXiv subjects

Andrew Adamatzky

Publications and source records attributed to Andrew Adamatzky.

At least 163 records · Page 9Linked to original sources
arXiv2013

How beta-skeletons lose their edges

A β-skeleton is a proximity graphs with node neighbourhood defined by continuous-valued parameter β. Two nodes in a β-skeleton are connected by an edge if their lune-based neighbourhood contains no other nodes. With increase of β some edges a skeleton are disappear. We study how a number of edges in β-skeleton depends on β. We speculate how this dependence can be used to discriminate between random and non-random planar sets. We also analyse stability of β-skeletons and their sensitivity to perturbations.

cs.CG↗
arXiv2013

The effect of changing electrode metal on solution-processed flexible titanium dioxide memristors

Flexible solution processed memristors show different behaviour dependent on the choice of electrode material. Use of gold for both electrodes leads to switchable WORM (Write Once Read Many times) resistive devices. Use of aluminium for both electrodes increases the richness of behaviour allowing both curved and triangular memristive switching resistance memories. A comparison device with an aluminium bottom electrode and gold top electrode only exhibited significant memristive resistance switching when the aluminium electrode was the cathode, suggesting that the electrode is acting as a source/sink of oxygen anions. When the gold electrode was the cathode this electrode was deformed by oxygen evolution. These results demonstrate that aluminium is helpful for stabilising and promoting memristive behaviour in sol-gel TiO$_2$ devices and that changing electrodes from aluminium to gold creates fundamentally different device characteristics.

cond-mat.mtrl-sci↗
arXiv2013

Which Memristor Theory is Best for Relating Devices Properties to Memristive Function?

There are three theoretical models which purport to relate experimentally-measurable or fabrication-controllable device properties to the memristor's operation: 1. Strukov et al's phenomenological model; 2. Georgiou et al's Bernoulli rewrite of that phenomenological model; 3. Gale's memory-conservation model. They differ in their prediction of the effect on memristance of changing the electrode size and factors that affect the hysteresis. Using a batch of TiO$_2$ sol-gel memristors fabricated with different top electrode widths we test and compare these three theories. It was found that, contrary to model 2's prediction, the `dimensionless lumped parameter', $β$, did not correlate to any measure of the hysteresis. Contrary to model 1, memristance was found to be dependent on the three spatial dimensions of the TiO$_2$ layer, as was predicted by model 3. Model 3 was found to fit the change in resistance value with electrode size. Simulations using model 3 and experimentally derived values for contact resistance gave hysteresis values that were linearly related to (and only one order of magnitude out) from the experimentally-measured values. Memristor hysteresis was found to be related to the ON state resistance and thus the electrode size (as those two are related). These results offer a verification of the memory-conservation theory of memristance and its association of the vacancy magnetic flux with the missing magnetic flux in memristor theory. This is the first paper to experimentally test various theories pertaining to the operation of memristor devices.

cond-mat.mtrl-sci↗
arXiv2013

Towards slime mould colour sensor: Recognition of colours by Physarum polycephalum

Acellular slime mould Physarum polycephalum is a popular now user-friendly living substrate for designing of future and emergent sensing and computing devices. P. polycephalum exhibits regular patterns of oscillations of its surface electrical potential. The oscillation patterns are changed when the slime mould is subjected to mechanical, chemical, electrical or optical stimuli. We evaluate feasibility of slime-mould based colour sensors by illuminating Physarum with red, green, blue and white colours and analysing patterns of the slime mould's electrical potential oscillations. We define that the slime mould recognises a colour if it reacts to illumination with the colour by a unique changes in amplitude and periods of oscillatory activity. In laboratory experiments we found that the slime mould recognises red and blue colour. The slime mould does not differentiate between green and white colours. The slime mould also recognises when red colour is switched off. We also map colours to diversity of the oscillations: illumination with a white colour increases diversity of amplitudes and periods of oscillations, other colours studied increase diversity either of amplitude or period.

cs.ET↗
arXiv2013

Routing of Physarum polycephalum signals using simple chemicals

In previous work the chemotaxis towards simple organic chemicals was assessed. We utilise the knowledge gained from these chemotactic assays to route Physarum polycephalum at a series of junctions. By applying chemical inputs at a simple T-junction we were able to reproducibly control the path taken by the plasmodium of P. Polycephalum. Where the chemoattractant farnesene was used at one input a routed signal could be reproducibly generated i.e. P. Polycephalum moves towards the source of chemoattractant. Where the chemoattractant was applied at both inputs the signal was reproducibly split. If a chemorepellent was used then the signal was reproducibly suppressed. If no chemical input was used in the simple circuit then a random signal was generated, whereby P. Polycephalum would move towards one output at the junction, but the direction was randomly selected. We extended this study to a more complex series of T-junctions to explore further the potential of routing P. Polycephalum. Although many of the circuits were completed effectively, any errors from the implementation of the simple T-junction were magnified. There were also issues with cascading effects through multiple junctions. For example signal splitting could be reproducibly initiated at the first junction but not at subsequent junctions. This work highlights the potential for exploiting chemotaxis to achieve complex and reliable routing of P. Polycephalum signals. This may be useful in implementing computing algorithms, design of autonomous robots and directed material synthesis. In additional experiments we showed that the application of chemoattractant compounds at specific locations on a homogeneous substrate could be used to reliably control the spatial configuration of P. Polycephalum. This may have applications in implementing geometric calculations and in robot navigation tasks such as mapping chemical plumes.

cs.ET↗
arXiv2013

Towards Hybrid Artificial-Slime Mould Devices

The plasmodium of the slime mould Physarum polycephalum has recently received significant attention for its value as a highly malleable amorphous computing substrate. In laboratory-based experiments, micro- and nanoscale artificial circuit components were introduced into the P. polycephalum plasmdodium to investigate the electrical properties and computational abilities of hybridised slime mould. It was found through a combination of imaging techniques and electrophysiological measurements that P. polycephalum is able to internalise a range of electrically active nanoparticles, assemble them in vivo and distribute them around the plasmodium. Hybridised plasmodium is able to form biomorphic mineralised networks, both inside the living plasmodium and the empty trails left in its wake by taxis, both of which facilitate the transmission of electricity. Hybridisation also alters the bioelectrical activity of the plasmodium and likely influences its information processing capabilities. It was concluded that hybridised slime mould is a suitable substrate for producing functional unconventional computing devices.

cs.ET↗
arXiv2013

On the internalisation, intraplasmodial carriage and excretion of metallic nanoparticles in the slime mould Physarum polycephalum

The plasmodium of Physarum polycephalum is a large single cell visible with the naked eye. When inoculated on a substrate with attractants and repellents the plasmodium develops optimal networks of protoplasmic tubes which span sites of attractants (i.e. nutrients) yet avoid domains with a high nutrient concentration. It should therefore be possible to program the plasmodium towards deterministic adaptive transformation of internalised nano- and micro-scale materials. In laboratory experiments with magnetite nanoparticles and glass micro-spheres coated with silver metal we demonstrate that the plasmodium of P. polycephalum can propagate the nano-scale objects using a number of distinct mechanisms including endocytosis, transcytosis and dragging. The results of our experiments could be used in the development of novel techniques targeted towards the growth of metallised biological wires and hybrid nano- and micro-circuits.

cs.ET↗
arXiv2013

Physarum wires: Self-growing self-repairing smart wires made from slime mould

We report experimental laboratory studies on developing conductive pathways, or wires, using protoplasmic tubes of plasmodium of acellular slime mould Physarum polycephalum. Given two pins to be connected by a wire, we place a piece of slime mould on one pin and an attractant on another pin. Physarum propagates towards the attract and thus connects the pins with a protoplasmic tube. A protoplasmic tube is conductive, can survive substantial over-voltage and can be used to transfer electrical current to lightning and actuating devices. In experiments we show how to route Physarum wires with chemoattractants and electrical fields. We demonstrate that Physarum wire can be grown on almost bare breadboards and on top of electronic circuits. The Physarum wires can be insulated with a silicon oil without loss of functionality. We show that a Physarum wire self-heals: end of a cut wire merge together and restore the conductive pathway in several hours after being cut. Results presented will be used in future designs of self-growing wetware circuits and devices, and integration of slime mould electronics into unconventional bio-hybrid systems.

physics.bio-ph↗
arXiv2013

Evolving Gene Regulatory Networks with Mobile DNA Mechanisms

This paper uses a recently presented abstract, tuneable Boolean regulatory network model extended to consider aspects of mobile DNA, such as transposons. The significant role of mobile DNA in the evolution of natural systems is becoming increasingly clear. This paper shows how dynamically controlling network node connectivity and function via transposon-inspired mechanisms can be selected for in computational intelligence tasks to give improved performance. The designs of dynamical networks intended for implementation within the slime mould Physarum polycephalum and for the distributed control of a smart surface are considered.

cs.CE↗
arXiv2013

Slimy hairs: Hair sensors made with slime mould

Slime mould Physarum polycephalum is a large single cell visible by unaided eye. We design a slime mould implementation of a tactile hair, where the slime mould responds to repeated deflection of hair by an immediate high-amplitude spike and a prolonged increase in amplitude and width of its oscillation impulses. We demonstrate that signal-to-noise ratio of the Physarum tactile hair sensor averages near six for the immediate response and two for the prolonged response.

cs.ET↗
arXiv2013

Slime mould tactile sensor

Slime mould P. polycephalum is a single cells visible by unaided eye. The cells shows a wide spectrum of intelligent behaviour. By interpreting the behaviour in terms of computation one can make a slime mould based computing device. The Physarum computers are capable to solve a range of tasks of computational geometry, optimisation and logic. Physarum computers designed so far lack of localised inputs. Commonly used inputs --- illumination and chemo-attractants and -repellents --- usually act on extended domains of the slime mould's body. Aiming to design massive-parallel tactile inputs for slime mould computers we analyse a temporal dynamic of P. polycephalum's electrical response to tactile stimulation. In experimental laboratory studies we discover how the Physarum responds to application and removal of a local mechanical pressure with electrical potential impulses and changes in its electrical potential oscillation patterns.

cs.ET↗
arXiv2013

Game of Life on Phyllosilicates: Gliders, Oscillators and Still Life

A phyllosilicate is a sheet of silicate tetrahedra bound by basal oxygens. A phyllosilicate automaton is a regular network of finite state machines --- silicon nodes and oxygen nodes --- which mimics structure of the phyllosilicate. A node takes states 0 and 1. Each node updates its state in discrete time depending on a sum of states of its three (silicon) or six (oxygen) neighbours. Phyllosilicate automata exhibit localizations attributed to Conway's Game of Life: gliders, oscillators, still lifes, and a glider gun. Configurations and behaviour of typical localizations, and interactions between the localizations are illustrated.

nlin.CG↗
arXiv2013

On Creativity of Elementary Cellular Automata

We map cell-state transition rules of elementary cellular automata (ECA) onto the cognitive control versus schizotypy spectrum phase space and interpret cellular automaton behaviour in terms of creativity. To implement the mapping we draw analogies between a degree of schizotypy and generative diversity of ECA rules, and between cognitive control and robustness of ECA rules (expressed via Derrida coefficient). We found that null and fixed point ECA rules lie in the autistic domain and chaotic rules are 'schizophrenic'. There are no highly articulated 'creative' ECA rules. Rules closest to 'creativity' domains are two-cycle rules exhibiting wave-like patterns in the space-time evolution.

nlin.CG↗
arXiv2013

On oscillators in phyllosilicate excitable automata

Phyllosilicate is a sheet of silicate tetrahedra bound by basal oxygens. A phyllosilicate excitable automaton is a regular network of finite state machines, which mimics structure of a silicate sheet. A node of the silicate sheet is an automaton, which takes resting, excited and refractory states, and updates its state in discrete time depending on a sum of excited states of its three (silicon automata) or six (oxygen automata) closest neighbours. Oscillator is a localised compact configuration of non-quiescent states which undergoes finite growth and modification but returns to its original state in a finite number of steps. We show that phyllosilicate excitable automata exhibit spiral and target waves, and oscillating localisation dynamics. Basic types of oscillators are classified and characterised.

nlin.CG↗
arXiv2013

Bio-imitaiton of Mexican migration routes to the USA with slime mould on 3D terrains

Plasmodium of Physarum polycephalum is a large single cell visible by unaided eye. It shows sophisticated behavioural traits in foraging for nutrients and developing an optimal transport network of protoplasmic tubes spanning sources of nutrients. When placed in an environment with distributed sources of nutrients the cell 'computes' an optimal graph spanning the nutrients by growing a network of protoplasmic tubes. P. polycephalum imitates development of man-made transport networks of a country when configuration of nutrients represents major urban areas. We employ this feature of the slime mould to imitate mexican migration to USA. The Mexican migration to USA is the World's largest migration system. We bio-physically imitate the migration using slime mould P. polycephalum. In laboratory experiments with 3D Nylon terrains of USA we imitated development of migratory routes from Mexico-USA border to ten urban areas with high concentration of Mexican migrants. From results of laboratory experiments we extracted topologies of migratory routes, and highlighted a role of elevations in shaping the human movement networks.

cs.ET↗
arXiv2013

On growing connected beta-skeletons

A $β$-skeleton, $β\geq 1$, is a planar proximity undirected graph of an Euclidean points set, where nodes are connected by an edge if their lune-based neighbourhood contains no other points of the given set. Parameter $β$ determines the size and shape of the lune-based neighbourhood. A $β$-skeleton of a random planar set is usually a disconnected graph for $β>2$. With the increase of $β$, the number of edges in the $β$-skeleton of a random graph decreases. We show how to grow stable $β$-skeletons, which are connected for any given value of $β$ and characterise morphological transformations of the skeletons governed by $β$ and a degree of approximation. We speculate how the results obtained can be applied in biology and chemistry.

cs.CG↗
arXiv2013

On Creativity of Slime Mould

Slime mould Physarum polycephalum is large single cell with intriguingly smart behaviour. The slime mould shows outstanding abilities to adapt its protoplasmic network to varying environmental conditions. The slime mould can solve tasks of computational geometry, image processing, logics and arithmetics when data are represented by configurations of attractants and repellents. We attempt to map behavioural patterns of slime onto the cognitive control versus schizotypy spectrum phase space and thus interpret slime mould's activity in terms of creativity.

cs.ET↗