Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 64 for “"quantisation"”.
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Kippenhahn's Conjecture: Counterexamples and Quantisation
… of any dimension, a process often referred to as quantisation. A quantum version of Kippenhahn's Conjecture, known as the Quantum Kippenhahn Theorem, has recently been proven by Klep and Volcic: if H and K generate the full matrix algebra, then there must be some X and Y such that X⊕H + Y⊕K has at …
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Skyrmions -- beyond rigid body quantisation
… most calculations to date have used rigid body quantisation, where the Skyrmions are allowed to rotate but remain rigid. The method reproduces some experimental results for light nuclei but there are some contradictions with data. In this thesis we study a more sophisticated quantisation scheme …
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Improved detection and quantisation of keypoints in the complex wavelet domain
… the use of random forests for descriptor quantisation. Firstly, we extended earlier work on keypoint detection energy functions. Existing complex wavelet based detectors were observed to suffer from two defects: a tendency to produce keypoints on straight edges at particular orientations …
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From Encoding to Decoding: Advancing Spiking Neural Network Technology for Improved Learning
… Transform preprocessing followed by sigma-delta quantisation with iterative error feedback, enabling frequency-domain spike encoding of images and time-domain encoding of speech signals. A companion compressor, DyNEDc, combines run-length encoding with Huffman coding to losslessly compress the …
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Steganography-based secret and reliable communications: Improving steganographic capacity and imperceptibility
… based on using 16x16 non-overlapping blocks and quantisation table for Joint Photographic Experts Group (JPEG) compression instead of 8x8. Then, the quality of JPEG stego images was enhanced by using optimised quantisation tables instead of the default tables. The second method, the hybrid …
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Bödeker's Effective Theory: From Langevin Dynamics to Dyson-Schwinger Equations
… equations. Using methods known from stochastic quantisation, we recast Bödeker's Langevin equation in the form of a field theoretic path integral. We argue that a physically reasonable truncation of the Dyson-Schwinger equations requires the introduction of gauge ghosts, which in general is not …
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New variants of variable neighbourhood search for 0-1 mixed integer programming and clustering
… and clustering with application to colour image quantisation. Several new heuristics for 0-1 mixed integer programming problem are developed, based on the principle of variable neighbourhood search. One set of proposed heuristics consists of improvement heuristics, which attempt to find …
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Computational Complexity Optimization on H.264 Scalable/Multiview Video Coding
… complexity. In the proposed scheme, the quantisation parameter can be computed directly instead of using the exhaustive Rate-Quantization model. The linear Mean Absolute Distortion (MAD) prediction model is used to predict the scene change, and the quantisation parameter will be increased …
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Orbital stability in a classical pilot-wave system
… focuses on the features responsible for the quantisation of orbital radii, and rationalises this quantisation in terms of the stability of circular orbits arising in the presence of a rotating frame and a central force. We find that orbital quantisation is most pronounced when the waves …
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Quantised charge pumping in a perpendicular magnetic field
… important observation is an enhancement of the quantisation as a result of the applied field. To determine the accuracy of the quantisation we applied novel measurement techniques and compared the pumped current with an accurate current generated using primary electrical standards. The reader …
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Body Sway and Aim Point Fluctuation in Rifle and Pistol Shooters
This study examined the effects of quantisation of force plate data used to measure body sway and the relationship between this body sway, aim point fluctuation and performance in shooting. Quantisation error in and resolution of selected body sway parameters were calculated from force plate data …
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New strategies for low noise, agile PLL frequency synthesis
… of identical form to fractional spurs caused in quantisation process. This effect directly introduces high spurs on some channels of the synthesiser output. Numerical and analytic results describing this effect are presented and amplitude and distribution of the resulting fractional spurs are …
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Fractal image compression and the self-affinity assumption : a stochastic signal modelling perspective
… coding purposes. The usual analogy with vector quantisation, in which each image is considered to be represented in terms of code vectors extracted from the image itself is instructive, but transforms the fundamental problem into one of understanding why this construction results in an efficient …
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Operads and moduli spaces
… invariants of manifolds arising in the quantisation of Chern-Simons field theory.
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Fermion Quantum Field Theory In Black-hole Spacetimes
… then employed for the purposes of a canonical quantisation of the corresponding fermionic theory. At the same time, we suggest that it may be impossible to extend a quantum field theory continuously across an event horizon. This split of a quantum field theory ensures the thermal character of …
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Image retrieval, object recognition, and discriminative models
… based on Gaussian mixtures which abandons vector quantisation, can be trained discriminatively, and can incorporate spatial relationships. This model is then rewritten and extended toward log-linear mixtures and support vector machines. We also present a random-forest-based approach that fuses …
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A measurement system for and the measurement system of single particle energies in quantum dots
… dot. These effects are a direct result of the quantisation of charge. Energy quantisation due to the confinement of the electrons wave-function, also plays a role in quantum dot devices. In the devices studied the classical charging energy, that gives rise to the Coulomb oscillations is …
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Towards the use of sub-band processing in automatic speaker recognition
… is presented. It involves creating a vector quantisation (VQ) model for each potential impostor and testing this impostor model against the genuine speaker’s VQ model. The ranking of these model vs. model scores is indicative of the final ranking of the impostors, as determined by the test …
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Low-dimensional electron transport and surface acoustic waves in GaAs and ZnO heterostructures
… and have analysed error mechanisms in SAW-driven quantisation (I=Nef, where N is the number of electrons in each SAW minimum, and f is the SAW resonant frequency). From energy spectroscopy measurements, we probe the electron energy inside a SAW-driven dynamic quantum dot and find that the small …
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