Martin Trefzer
University of York, Electronics, Faculty Member
QCM-D data in .csv format. File contains overtone-normalized frequency changes for thirteenth overtone as a function of time, with the corresponding dissipation changes
Research Interests:
This paper describes a novel multi-reconfigurable architecture, which allows variability-aware design, rapid prototyping and post-fabrication optimisation of digital systems. This is achieved by exploiting reconfiguration at both the... more
This paper describes a novel multi-reconfigurable architecture, which allows variability-aware design, rapid prototyping and post-fabrication optimisation of digital systems. This is achieved by exploiting reconfiguration at both the digital function level and the transistor level. A runtime variability map of the architecture, created using ring oscillators, is presented.
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Research Interests:
Robot interaction planning is a computationally expensive process which rarely makes use of previous experiences in a deliberative manner. This paper addresses this issue by examining dimensionality reduction techniques to allow... more
Robot interaction planning is a computationally expensive process which rarely makes use of previous experiences in a deliberative manner. This paper addresses this issue by examining dimensionality reduction techniques to allow comparison of objects in a robot's environment based on the way they react to robot manipulation. We compare a number of techniques which can map objects from an observation space, which may contain thousands of dimensions, to a lower dimensionality space — the embedding space — which allows objects to be compared in an efficient manner, making knowledge transfer between similar objects more computationally tractable.
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Research Interests:
Research Interests:
Agarose gel showing assembly of a surface connector, two folded squares and an unfolded square
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QCM-D data in .csv format. File contains overtone-normalized frequency changes for thirteenth overtone as a function of time, with the corresponding dissipation changes.Data corresponds to four experiments: 1. folded square A supplied... more
QCM-D data in .csv format. File contains overtone-normalized frequency changes for thirteenth overtone as a function of time, with the corresponding dissipation changes.Data corresponds to four experiments: 1. folded square A supplied with unfolded square B. 2. folded blocked square A supplied with unblocking strand and then unfolded square B. 3. folded square A supplied with folded square B. 4. full motor supplied sequentially with both unblocking strands
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Technical Group members are being offered the option of receiving the Holography Newsletter in an electronic format. An e-mail notice is being sent to all group members advising you of the web site location for this issue and asking you... more
Technical Group members are being offered the option of receiving the Holography Newsletter in an electronic format. An e-mail notice is being sent to all group members advising you of the web site location for this issue and asking you to choose between the electronic or printed version for future issues. If you have not yet received this e-mail message, then SPIE does not have your correct e-mail address in our database. To receive future issues of this newsletter in the electronic format please send your e-mail address to spiemembership@spie.org with the word HOLOGRAPHY in the subject line of the message and the words "Electronic version" in the body of the message. If you prefer to continue to receive the newsletter in the printed format, but want to send your correct e-mail address for our database, include the words "Print version preferred" in the body of your message. NOVEMBER 2001 VOL. 12, NO. 2
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One of the greatest challenges in Evolvable Hardware—in particular when dealing with intrinsic evolution—is to monitor and assess the performance of an (evolving) circuit or system in order to arrive at a solution that ultimately meets... more
One of the greatest challenges in Evolvable Hardware—in particular when dealing with intrinsic evolution—is to monitor and assess the performance of an (evolving) circuit or system in order to arrive at a solution that ultimately meets the design specifications. In order to be able to accurately assess performance it is necessary to accurately measure not only input/output characteristics, but also properties such as power consumption, resource consumption and temperature. From these measurements desired performance characteristics can then be calculated; the formula (or algorithm) that achieves this is called the fitness function. Once more borrowing terminology from biology, the fitness of a design under test represents its performance on one or more previously defined objectives. The fitness value is then used by the evolutionary algorithm to rank a population of candidate solutions (individuals), hence to decide which ones shall survive and produce offspring, and which ones shall be discarded. Note that although this chapter is mostly about electronic systems, many of the problems addressed are generic to all evolved physical systems and just the way certain properties manifest themselves changes. For example, in electronic circuits “device variability” occurs as a result of the manufacturing process and the equivalent in biological organisms would be “cell diversity”, which occurs due to how growth takes place.
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... time. Author(s): Jayan Thomas; Muhsin Eralp; Savas Tay; Guogiang Li; Seth R. Marder; Gerald R. Meredith; Axel Schulzgen; Robert A ... Hybrid integrated optics in volume holographic photopolymer. Author(s): Robert R. McLeod; Amy C.... more
... time. Author(s): Jayan Thomas; Muhsin Eralp; Savas Tay; Guogiang Li; Seth R. Marder; Gerald R. Meredith; Axel Schulzgen; Robert A ... Hybrid integrated optics in volume holographic photopolymer. Author(s): Robert R. McLeod; Amy C. Sullivan; Matthew W. Grabowski; Timothy ...
ABSTRACT A novel approach to 3D optical information storage based on writing and reading of microscopic holographic gratings in a photopolymer layer is presented. Strongly localized reflection gratings created by two highly focused laser... more
ABSTRACT A novel approach to 3D optical information storage based on writing and reading of microscopic holographic gratings in a photopolymer layer is presented. Strongly localized reflection gratings created by two highly focused laser beams are used to replace the pit and land structure of the CD/DVD technology. The holographic recording method presented here allows employing various multiplexing methods. A combination of wavelength multiplexing and multilayer storage is proposed to achieve storage densities similar to page-oriented holographic data storage. In this paper we report on recording and readout of submicron-sized gratings using diffraction limited laser beams. The transversal extent of a micrograting corresponds to the optical resolution limit. Track spacing and bit-to-bit separation are about 500 nm. The interlayer spacing through the depth of the photopolymer is less than 8 micron. This way a 3D structure is realized that even refines the surface data structure of current DVDs.
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State-of-the-art Convolutional Neural Networks (CNNs) have become increasingly accurate. However, hundreds or thousands of megabytes data are involved to store them, making these networks also computationally expensive. For certain... more
State-of-the-art Convolutional Neural Networks (CNNs) have become increasingly accurate. However, hundreds or thousands of megabytes data are involved to store them, making these networks also computationally expensive. For certain applications, such as Internet-of-Things (IoT), where such CNNs are to be implemented on resource-constrained and memory-constrained platforms, including Field-Programmable Gate Arrays (FPGAs) and embedded devices, CNN architectures and parameters have to be small and efficient. In this paper, an evolutionary algorithm (EA) based adaptive integer quantisation method is proposed to reduce network size. The proposed method uses single objective rank-based evolutionary strategy to find the best quantisation bin boundary for fixed quantised bit width. The performance of the proposed method is evaluated on a small CNN, the LeNet-5 architecture, using the CIFAR-10 dataset. The aim is to devise a methodology that allows adaptive quantisation of both weights and bias from 32-bit floating point to 8-bit integer representation for LeNet-5, while retaining accuracy. The experiments compare straight-forward (linear) quantisation from 32-bits to 8-bits with the proposed adaptive quantisation method. The results show that the proposed method is capable of quantising CNNs to lower bit width representation with only a slight loss in classification accuracy.
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Research Interests: Computer Science and IEEE
Molecular computation with DNA has great potential for low power, highly parallel information processing in a biological or biochemical context. However, significant challenges remain for the field of DNA computation. New technology is... more
Molecular computation with DNA has great potential for low power, highly parallel information processing in a biological or biochemical context. However, significant challenges remain for the field of DNA computation. New technology is needed to allow multiplexed label-free readout and to enable regulation of molecular state without addition of new DNA strands. These capabilities could be provided by hybrid bioelectronic systems in which biomolecular computing is integrated with conventional electronics through immobilization of DNA machines on the surface of electronic circuitry. Here we present a quantitative experimental analysis of a surface-immobilized OR gate made from DNA and driven by strand displacement. The purpose of our work is to examine the performance of a simple representative surface-immobilized DNA logic machine, to provide valuable information for future work on hybrid bioelectronic systems involving DNA devices. We used a quartz crystal microbalance to examine a ...
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An optical system for writing and reading of microscopic holographic gratings in a photopolymer layer is presented. The reflection gratings created by a highly focused laser beam can be used to replace the pit-land structure in a... more
An optical system for writing and reading of microscopic holographic gratings in a photopolymer layer is presented. The reflection gratings created by a highly focused laser beam can be used to replace the pit-land structure in a disk-based optical storage system. The modulation range of such three-dimensional microgratings is clearly localized to the focal region of a focused write beam.
Research Interests:
A novel approach to 3D optical information storage based on writing and reading of microscopic holographic gratings in a photopolymer layer is investigated. The reflection gratings created by a highly focused laser beam can be used to... more
A novel approach to 3D optical information storage based on writing and reading of microscopic holographic gratings in a photopolymer layer is investigated. The reflection gratings created by a highly focused laser beam can be used to replace the pit-land structure in a disk-based optical storage system. The modulation range of such 3D microgratings is clearly localized to the focal
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Levodopa is a drug that is commonly used to treat movement disorders associated with Parkinson's disease. Its dosage requires careful monitoring, since the required amount changes over time, and excess dosage can lead to muscle spasms... more
Levodopa is a drug that is commonly used to treat movement disorders associated with Parkinson's disease. Its dosage requires careful monitoring, since the required amount changes over time, and excess dosage can lead to muscle spasms known as levodopa-induced dyskinesia. In this work, we investigate the potential for using epiNet, a novel artificial gene regulatory network, as a classifier for monitoring accelerometry time series data collected from patients undergoing levodopa therapy. We also consider how dynamical analysis of epiNet classifiers and their transitions between different states can highlight clinically useful information which is not available through more conventional data mining techniques. The results show that epiNet is capable of discriminating between different movement patterns which are indicative of either insufficient or excessive levodopa.
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In this paper new genetic operators are introduced that inherently avoid oating terminals and broken routes while evolving transistor circuits on a CMOS eld programmable transistor array (FPTA). They are designed to facilitate... more
In this paper new genetic operators are introduced that inherently avoid oating terminals and broken routes while evolving transistor circuits on a CMOS eld programmable transistor array (FPTA). They are designed to facilitate understanding and improve transferability of the resulting circuits. Comparators and logic gates (AND, OR, XOR) have been evolved with the proposed algorithm and the re-sults are compared to corresponding experiments that use a straight forward implementation of the genetic operators. Furthermore, netlists are extracted from the evolved circuits and simulated with a SPICE simulator. The simulation re-sults are compared with measurements performed on the chip. 1
Levodopa is a drug that is commonly used to treat movement disorders associated with Parkinson’s disease. Its dosage requires careful monitoring, since the required amount changes over time, and excess dosage can lead to muscle spasms... more
Levodopa is a drug that is commonly used to treat movement disorders associated with Parkinson’s disease. Its dosage requires careful monitoring, since the required amount changes over time, and excess dosage can lead to muscle spasms known as levodopa-induced dyskinesia. In this work, we investigate the potential for using epiNet, a novel artificial gene regulatory network, as a classifier for monitoring accelerometry time series data collected from patients undergoing levodopa therapy. We also consider
The growing impact of the network on the overall power consumption of many-core systems introduces a need for mechanisms that reduce the power required for data communication without significantly impacting performance. This paper... more
The growing impact of the network on the overall power consumption of many-core systems introduces a need for mechanisms that reduce the power required for data communication without significantly impacting performance. This paper proposes a low-overhead mechanism for frequency control of individual channels in a Network-on-Chip system. The proposed mechanism is low-overhead, distributed and easy to tune for varying traffic, which are crucial aspects in a many-core context. This is primarily achieved by the asymmetry of the controller, which defines different responses for increases and decreases in performance requirements, allowing a channel to operate at the minimum required frequency without adversely affecting stability, necessary for subsequent voltage scaling.
Advances in artificial intelligence are driven by technologies inspired by the brain, but these technologies are orders of magnitude less powerful and energy efficient than biological systems. Inspired by the nonlinear dynamics of neural... more
Advances in artificial intelligence are driven by technologies inspired by the brain, but these technologies are orders of magnitude less powerful and energy efficient than biological systems. Inspired by the nonlinear dynamics of neural networks, new unconventional computing hardware has emerged with the potential for extreme parallelism and ultra-low power consumption. Physical reservoir computing demonstrates this with a variety of unconventional systems from optical-based to spintronic [1]. Reservoir computers provide a nonlinear projection of the task input into a highdimensional feature space by exploiting the system’s internal dynamics. A trained readout layer then combines features to perform tasks, such as pattern recognition and time-series analysis. Despite progress, achieving state-of-the-art performance without external signal processing to the reservoir remains challenging. Here we show, through simulation, that magnetic materials in thin-film geometries can realise re...
We explore the effect of structure and connection complexity on the dynamical behaviour of Reservoir Computers (RC). At present, considerable effort is taken to design and hand-craft physical reservoir computers. Both structure and... more
We explore the effect of structure and connection complexity on the dynamical behaviour of Reservoir Computers (RC). At present, considerable effort is taken to design and hand-craft physical reservoir computers. Both structure and physical complexity are often pivotal to task performance, however, assessing their overall importance is challenging. Using a recently proposed framework, we evaluate and compare the dynamical freedom (referring to quality) of neural network structures, as an analogy for physical systems. The results quantify how structure affects the range of behaviours exhibited by these networks. It highlights that high quality reached by more complex structures is often also achievable in simpler structures with greater network size. Alternatively, quality is often improved in smaller networks by adding greater connection complexity. This work demonstrates the benefits of using abstract behaviour representation, rather than evaluation through benchmark tasks, to asse...
We present a plugin for the ARGoS robot simulator which enables the use of 3D physics simulation and definition of objects and entities without the need to develop new entities in C++. We provide the facility for entities to be loaded and... more
We present a plugin for the ARGoS robot simulator which enables the use of 3D physics simulation and definition of objects and entities without the need to develop new entities in C++. We provide the facility for entities to be loaded and added to simulations using a URDF inspired XML format. Loading of entities, physics simulation and rendering is all handled by the plugin, removing the need for knowledge of specific engines or OpenGL. This paves the way for ARGoS to be used not only for development and evaluation of controllers but also for evolution of robot morphologies and co-evolution of controllers and morphologies which was previously not possible without a considerable development overhead.
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Research Interests:
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For almost 150 years, the capacitor (discovered in 1745), the resistor (1827) and the inductor (1831) have been the only fundamental passive devices known and have formed the trinity of fundamental passive circuit elements, which,... more
For almost 150 years, the capacitor (discovered in 1745), the resistor (1827) and the inductor (1831) have been the only fundamental passive devices known and have formed the trinity of fundamental passive circuit elements, which, together with transistors, form the basis of all existing electronic devices and systems. There are only a few fundamental components and each of them performs its own characteristic function that is unique amongst the family of basic components. For example, capacitors store energy in an electric field, inductors store energy in a magnetic field, resistors dissipate electrical energy, and transistors act as switches and amplify electrical energy. It then happened in 1971 when Leon Chua, a professor of electrical engineering at the University of Berkeley, postulated the existence of a fourth fundamental passive circuit element, the memristor (Chua in IEEE Transactions on Circuit Theory 18(5):507–519, 1971). Chua suggested that this fourth device, which was only hypothetical at that point, must exist to complete the conceptual symmetry with the resistor, capacitor and inductor in respect of the four fundamental circuit variables such as voltage, current, charge and flux. He proved theoretically that the behaviour of the memristor could not be substituted by a combination of the other three circuit elements, hence that the memristor a truly fundamental device. This chapter is about the remarkable discovery of the “fourth fundamental passive circuit element”, the memristor. Its name is an amalgamation of the words “memory” and “resistor”, due to the memristor’s properties to act as a resistor with memory. Since the memristor belongs to the family of passive circuit elements, these will be focused here.
ABSTRACT A novel approach to 3D optical information storage based on writing and reading of microscopic holographic gratings in a photopolymer layer is presented. Wavelength multiplexing combined with multilayer storage results in high... more
ABSTRACT A novel approach to 3D optical information storage based on writing and reading of microscopic holographic gratings in a photopolymer layer is presented. Wavelength multiplexing combined with multilayer storage results in high storage densities.
Research Interests:
ABSTRACT A novel approach to 3D optical information storage based on writing and reading of microscopic holographic gratings in a photopolymer layer is presented. Wavelength multiplexing combined with multilayer storage results in high... more
ABSTRACT A novel approach to 3D optical information storage based on writing and reading of microscopic holographic gratings in a photopolymer layer is presented. Wavelength multiplexing combined with multilayer storage results in high storage densities.
Research Interests:
Research Interests:
Research Interests:
DNA molecular machines have great potential for use in computing systems. Since Adleman originally introduced the concept of DNA computing through his use of DNA strands to solve a Hamiltonian path problem, a range of DNA-based computing... more
DNA molecular machines have great potential for use in computing systems. Since Adleman originally introduced the concept of DNA computing through his use of DNA strands to solve a Hamiltonian path problem, a range of DNA-based computing elements have been developed, including logic gates, neural networks, finite state machines (FSMs) and non-deterministic universal Turing machines. DNA molecular machines can be controlled using electrical signals and the state of DNA nanodevices can be measured using electrochemical means. However, to the best of our knowledge there has as yet been no demonstration of a fully integrated biomolecular computing system that has multiple levels of information processing capacity, can accept electronic inputs and is capable of independent operation. Here we address the question of how such a system could work. We present simulation results showing that such an integrated hybrid system could convert electrical impulses into biomolecular signals, perform ...
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A quartz crystal microbalance with dissipation monitoring can be used to study the mass and structure of surface-immobilized layers of molecules, in real time. Here we describe the use of the technique to study DNA structures and devices.