155 research outputs found
Is Spiking Logic the Route to Memristor-Based Computers?
Memristors have been suggested as a novel route to neuromorphic computing
based on the similarity between neurons (synapses and ion pumps) and
memristors. The D.C. action of the memristor is a current spike, which we think
will be fruitful for building memristor computers. In this paper, we introduce
4 different logical assignations to implement sequential logic in the memristor
and introduce the physical rules, summation, `bounce-back', directionality and
`diminishing returns', elucidated from our investigations. We then demonstrate
how memristor sequential logic works by instantiating a NOT gate, an AND gate
and a Full Adder with a single memristor. The Full Adder makes use of the
memristor's memory to add three binary values together and outputs the value,
the carry digit and even the order they were input in.Comment: Conference paper. Work also reported in US patent: `Logic device and
method of performing a logical operation', patent application no. 14/089,191
(November 25, 2013
Beyond Markov Chains, Towards Adaptive Memristor Network-based Music Generation
We undertook a study of the use of a memristor network for music generation,
making use of the memristor's memory to go beyond the Markov hypothesis. Seed
transition matrices are created and populated using memristor equations, and
which are shown to generate musical melodies and change in style over time as a
result of feedback into the transition matrix. The spiking properties of simple
memristor networks are demonstrated and discussed with reference to
applications of music making. The limitations of simulating composing memristor
networks in von Neumann hardware is discussed and a hardware solution based on
physical memristor properties is presented.Comment: 22 pages, 13 pages, conference pape
On computing in fine-grained compartmentalised Belousov-Zhabotinsky medium
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 implement basic logical gates by colliding the
wave-fragments. We show that a vesicle filled with BZ mixture can implement a
range of basic logical functions. We cascade BZ-vesicle logical gates into
arithmetic circuits implementing addition of two one-bit binary numbers. We
envisage that our theoretical results will be applied in chemical laboratory
designs of massive-parallel computers based on fine-grained
compartmentalisation of excitable chemical systems
The Short-term Memory (D.C. Response) of the Memristor Demonstrates the Causes of the Memristor Frequency Effect
A memristor is often identified by showing its distinctive pinched hysteresis
curve and testing for the effect of frequency. The hysteresis size should
relate to frequency and shrink to zero as the frequency approaches infinity.
Although mathematically understood, the material causes for this are not well
known. The d.c. response of the memristor is a decaying curve with its own
timescale. We show via mathematical reasoning that this decaying curve when
transformed to a.c. leads to the frequency effect by considering a descretized
curve. We then demonstrate the validity of this approach with experimental data
from two different types of memristors.Comment: Conference paper, to appear in CASFEST 2014 June, Melbourn
Towards constructing one-bit binary adder in excitable chemical medium
Light-sensitive modification (ruthenium catalysed) of the
Belousov-Zhabotinsky medium exhibits various regimes of excitability depending
on the levels of illumination. For certain values of illumination the medium
switches to a sub-excitable mode. An asymmetric perturbation of the medium
leads to formation of a travelling localized excitation, a wave-fragment which
moves along a predetermined trajectory, ideally preserving its shape and
velocity. To implement collision-based computing with such wave-fragments we
represent values of Boolean variables in presence/absence of a wave-fragment at
specific sites of medium. When two wave-fragments collide they either
annihilate, or form new wave-fragments. The trajectories of the wave-fragments
after the collision represent a result of the computation, e.g. a simple
logical gate. Wave-fragments in the sub-excitable medium are famously difficult
to control. Therefore, we adopted a hybrid procedure in order to construct
collision-based logical gates: we used channels, defined by lower levels
illumination to subtly tune the shape of a propagating wave-fragment and allow
the wave-fragments to collide at the junctions between channels. Using this
methodology we were able to implement both in theoretical models (using the
Oregonator) and in experiment two interaction-based logical gates and assemble
the gates into a basic one-bit binary adder. We present the first ever
experimental approach towards constructing arithmetical circuits in
spatially-extended excitable chemical systems
Analysis of the volatiles in the headspace above the plasmodium and sporangia of the slime mould (Physarum polycephalum) by SPME-GCMS
Solid phase micro-extraction (SPME) coupled with Gas Chromatography Mass Spectrometry (GC-MS) was used to extract and analyse the volatiles in the headspace above the plasmodial and sporulating stages of the slime mould Physarum Polycephalum. In total 115 compounds were identified from across a broad range of chemical classes. Although more (87) volatile organic compounds (VOCs) were identified when using a higher incubation temperature of 75oC, a large number of compounds (79) were still identified at the lower extraction temperature of 30oC and where the plasmodial stage was living. Far fewer compounds were extracted after sporulation at the two extraction temperatures. There were some marked differences between the VOCs identified in the plasmodial stage and after sporulation. In particular the nitrogen containing compounds acetonitrile, pyrrole, 2, 5-dimethyl-pyrazine and trimethyl pyrazine seemed to be associated with the sporulating stage. There were many compounds associated predominantly with the plasmodial stage including a number of furans and alkanes. Interestingly, a number of known fungal metabolites were identified including 1-octen-3-ol, 3-octanone, 1-octen-3 one, 3-octanol. In addition known metabolites of cyanobacteria and actinobacteria in particular geosmin was identified in the headspace. Volatile metabolites that had previously been identified as having a positive chemotactic response to the plasmodial stage of P. polycephalum were also identified including {\beta} farnesene, {\beta}-myrcene, limonene and 3-octanone. This study constitutes the first comprehensive analysis of the headspace volatiles emitted from Physarum Polycephalum. Further work to understand the origin and function of the volatiles identified is required
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