3,692 research outputs found
The problem of detailed balance for the Feynman-Smoluchowski Engine (FSE) and the multiple pawl paradox
Full text linkDerek Abbott, Bruce R. Davis and Juan M. R. Parrond
The application of nonlinear bistable detectors to DCT-domain watermarking schemes
Full text linkCopyright 2008 Society of Photo-Optical Instrumentation Engineers. This paper was published in Complex Systems II, edited by Derek Abbott, Tomaso Aste, Murray Batchelor, Robert Dewar, Tiziana Di Matteo, Tony Guttmann, Proc. of SPIE Vol. 6802, 680215 and is made available as an electronic reprint with permission of SPIE. One print or electronic copy may be made for personal use only. Systematic or multiple reproduction, distribution to multiple locations via electronic or other means, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper are prohibited.A DCT-domain watermarking scheme, based on nonlinear bistable detectors, is presented. A binary copyright character, i.e. watermark, is firstly reordered into a binary zig-zag sequence, and then mapped into pulse amplitude modulated waveforms. A certain desynchronization time delay can be arbitrarily placed into one code of the modulated signal, and is tolerated due to the superior robustness of nonlinear detectors over matched filters. The watermark signal is then embedded in a selected set of DCT coefficients of an image in a medium frequency range. The selected set of DCT coefficients is shuffled via the Arnold transform and looks more like background noise with respect to the watermark signal. The copyright character can be extracted by the nonlinear bistable detector without prior knowledge of the original image, i.e. blind watermark detection. Interestingly, a higher match between the original watermark character and the extracted one can be further achieved using a parallel array of bistable detectors via the mechanism of array stochastic resonance. Robustness of the proposed watermarking scheme is shown in the presence of noise, filtering, cropping and compression.Fabing Duan and Derek Abbot
Finite element modelling of SAW correlator
Full text linkCopyright 2007 Society of Photo-Optical Instrumentation Engineers. This paper was published in BioMEMS and Nanotechnology III, edited by Dan V. Nicolau, Derek Abbott, Kourosh Kalantar-Zadeh, Tiziana Di Matteo, Sergey M. Bezrukov, Proc. of SPIE Vol. 6799, 679915 and is made available as an electronic reprint with permission of SPIE. One print or electronic copy may be made for personal use only. Systematic or multiple reproduction, distribution to multiple locations via electronic or other means, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper are prohibited.Numerical simulations of SAW correlators so far are limited to delta function and equivalent circuit models. These models are not accurate as they do not replicate the actual behaviour of the device. Manufacturing a correlator to specifically realise a different configuration is both expensive and time consuming. With the continuous improvement in computing capacity, switching to finite element modelling would be more appropriate. In this paper a novel way of modelling a SAW correlator using finite element analysis is presented. This modelling approach allows the consideration of different code implementation and device structures. This is demonstrated through simulation results for a 5×2-bit Barker sequence encoded SAW correlator. These results show the effect of both bulk and leaky modes on the device performance at various operating frequencies. Moreover, the ways in which the gain of the correlator can be optimised though variation of design parameters will also be outlined.Ajay C.Tikka Said F.Al-Sarawi and Derek Abbot
Classification of osteosarcoma T-ray responses using adaptive and rational wavelets for feature extraction
Full text linkCopyright 2007 Society of Photo-Optical Instrumentation Engineers. This paper was published in Complex Systems II, edited by Derek Abbott, Tomaso Aste, Murray Batchelor, Robert Dewar, Tiziana Di Matteo, Tony Guttmann, Proc. of SPIE Vol. 6802, 680211 and is made available as an electronic reprint with permission of SPIE. One print or electronic copy may be made for personal use only. Systematic or multiple reproduction, distribution to multiple locations via electronic or other means, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper are prohibited.In this work we investigate new feature extraction algorithms on the T-ray response of normal human bone cells and human osteosarcoma cells. One of the most promising feature extraction methods is the Discrete Wavelet Transform (DWT). However, the classification accuracy is dependant on the specific wavelet base chosen. Adaptive wavelets circumvent this problem by gradually adapting to the signal to retain optimum discriminatory information, while removing redundant information. Using adaptive wavelets, classification accuracy, using a quadratic Bayesian classifier, of 96.88% is obtained based on 25 features. In addition, the potential of using rational wavelets rather than the standard dyadic wavelets in classification is explored. The advantage it has over dyadic wavelets is that it allows a better adaptation of the scale factor according to the signal. An accuracy of 91.15% is obtained through rational wavelets with 12 coefficients using a Support Vector Machine (SVM) as the classifier. These results highlight adaptive and rational wavelets as an efficient feature extraction method and the enormous potential of T-rays in cancer detection.Desmond Ng, Wong Fu Tian, Withawat Withayachumnankul, David Findlay, Bradley Ferguson and Derek Abbot
Flow in left atrium using MR fluid motion estimation
Full text linkCopyright 2007 Society of Photo-Optical Instrumentation Engineers. This paper was published in Complex Systems II, edited by Derek Abbott, Tomaso Aste, Murray Batchelor, Robert Dewar, Tiziana Di Matteo, Tony Guttmann, Proc. of SPIE Vol. 6802, 68021H and is made available as an electronic reprint with permission of SPIE. One print or electronic copy may be made for personal use only. Systematic or multiple reproduction, distribution to multiple locations via electronic or other means, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper are prohibited.A recent development based on optical flow applied onto Fast Imaging in Steady State Free Precession (TrueFISP) magnetic resonance imaging is able to deliver good estimation of the flow profile in the human heart chamber. The examination of cardiac flow based on tracking of MR signals emitted by moving blood is able to give medical doctors insight into the flow patterns within the human heart using standard MRI procedure without specifically subjecting the patient to longer scan times using more dedicated scan protocols such as phase contrast MRI. Although MR fluid motion estimation has its limitations in terms of accurate flow mapping, the use of a comparatively quick scan procedure and computational post-processing gives satisfactory flow quantification and can assist in management of cardiac patients. In this study, we present flow in the left atria of five human subjects using MR fluid motion tracking. The measured flow shows that vortices exist within the atrium of heart. Although the scan is two-dimensional, we have produced multiple slices of flow maps in a spatial direction to show that the vortex exist in a three-dimensional space.Kelvin K. L. Wong, Richard M. Kelso, Stephen M. Worthley, Prash Sanders, Jagannath Mazumdar, Derek Abbot
2-stage RC ladder: solution of a noise paradox
Full text linkLaurens Weiss, Derek Abbott and Bruce R. Davi
Liquid metal enabled pump
No full textSmall-scale pumps will be the heartbeat of many future micro/nanoscale platforms. However, the integration of small-scale pumps is presently hampered by limited flow rate with respect to the input power, and their rather complicated fabrication processes. These issues arise as many conventional pumping effects require intricate moving elements. Here, we demonstrate a system that we call the liquid metal enabled pump, for driving a range of liquids without mechanical moving parts, upon the application of modest electric field. This pump incorporates a droplet of liquid metal, which induces liquid flow at high flow rates, yet with exceptionally low power consumption by electrowetting/deelectrowetting at the metal surface. We present theory explaining this pumping mechanism and show that the operation is fundamentally different from other existing pumps. The presented liquid metal enabled pump is both efficient and simple, and thus has the potential to fundamentally advance the field of microfluidics.Shi-Yang Tang, Khashayar Khoshmanesh, Vijay Sivan, Phred Petersen, Anthony P. OMullane,d, Derek Abbott, Arnan Mitchell, and Kourosh Kalantar-zade
GaAs MESFET Photodetectors for imaging arrays / by Derek Abbott.
Full text linkBibliography: p. 269-276.xxx, 306 p. : ill. ; 30 cm.The main objective of this thesis is to create a significant advance in the area of solid-state imaging via the research of an image sensor that can be ultimately integrated with high-speed gallium arsenide (GaAs) processing circuitry on a common substrate chip.Thesis (Ph.D.)--University of Adelaide, Dept. of Electrical and Electronic Engineering, 199
Parrondo's paradoxical games and the discrete Brownian ratchet
Full text linkGregory P. Harmer, Derek Abbott, Peter G. Taylor and Juan M. R. Parrond
A neuromorphic VLSI design for spike timing and rate based synaptic plasticity
Full text linkAbstract not availableMostafa Rahimi Azghadi, Said Al-Sarawi, Derek Abbott, Nicolangelo Iannell
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