We study the deformation quantisation (Moyal quantisation) of general constrained Hamiltonian systems. It is shown how second class constraints can be turned into first class quantum constraints. This is illustrated by the O(N) non-linear σ-model. Some new light is also shed on the Dirac bracket. Furthermore, it is shown how classical constraints not in involution with the classical Hamiltonian...

In this letter we wish to clarify in which sense the tensor nature of the commutation relations [x,x ] = iθ underlying Minkowski spacetime quantisation cannot be suppressed even in the twisted approach to Lorentz covariance. We then address the vexata quaestio: “why θ?”

The following two loosely connected sets of topics are reviewed in these lecture notes: 1) Gauge invariance, its treatment in field theories and its implications for internal symmetries and edge states such as those in the quantum Hall effect. 2) Quantisation on multiply connected spaces and a topological proof the spin-statistics theorem which avoids quantum field theory and relativity. Under ...

Introduction: With delta-sigma (D-S) modulators (DSMs) heading towards low-power high-speed applications with low oversampling ratio (OSR), the employing of higher-order noise shaping is necessary to achieve the desired signal-to-noise-and-distortion ratio (SNDR). The single-loop high-order DSM can provide the required SNDR with relaxed analogue circuit requirements, but is prone to loop instab...

Automatic language identi cation (LID) from the spoken speech utterance is a challenging problem. In this paper, we present an LID system that works for South Indian languages and Hindi. Each language is modeled using an approach based on Vector Quantisation [1]. The speech is segmented into di erent sounds (CVs) and the performance of the system on each of the segments is studied. Our studies ...

The effects of subjecting a digital image to more than one step of the lossy JPEG baseline data compression are studied. The performance in terms of the signal-to-noise ratio as well as the visual artifacts are observed and presented. Two types of visual artifacts have been identified and they are found to correlate closely to the two types of errors introduced when the Discrete Cosine Transfor...

A new characteristic waveform decomposition method based on wavelets is proposed for the Waveform Interpolation (WI) paradigm. In WI, pitch-cycle waveforms are filtered in the evolution domain to decompose the signal into two waveform surfaces, one characterising voiced speech and a second representing unvoiced speech. The slow roll-off of FIR filters leads, however, to a significant inter-rela...

In this paper, we present a novel bitstream scalable audio coder. In the proposed coder, the full bandwidth of input audio is first split into two. A hybrid WLPC–wavelet representation is used to encode the low frequency components ( 11 kHz). In this method, the excitation to the WLPC synthesis filter is decomposed into subbands using a wavelet filterbank, and perceptually encoded. Two stage qu...

Parham Zolfaghari Tony Robinson Cambridge University Engineering Department, Trumpington Street, Cambridge CB2 1PZ, UK. Tel: [+44] 1223 332754 Fax: [+44] 1223 332662 email : psz1000,[email protected] ABSTRACT This paper describes a new low bit-rate formant vocoder. The formant parameters are represented by Gaussian mixture distributions, which are estimated from the discrete Fourier transform (...

Quantisation of Lorentz invariant scalar field theory in Doplicher-Fredenhagen-Roberts (DFR) space-time, a invariant, non-commutative space-time is studied. We use an approach to quantisation that based on the equations motion alone and derive equal time commutation relation between Doplicher-Fredenhagen-Roberts-Amorim (DFRA) its conjugate, which has dependent modifications, but corresponding c...