Wyniki 1-2 spośród 2 dla zapytania: authorDesc:"Saule RAKHMETULLINA"

Integration of hidden markov models in the automated speaker recognition system for critical use DOI:10.15199/48.2019.04.32

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In speaker recognition systems (SRS) as a whole and in the automated speaker recognition system for critical use (ASRSCU) in particular, use the classical methods of pattern recognition theory, namely statistical simulation methods for describing the vectors of individual features of speech signals. Most often, in models of Gaussian mixtures [1, 2], artificial neural networks [3, 4] or support vector machines [5, 6, 7]. Less used are hidden Markov models [5, 6, 8, 9], which, however, together with Gaussian mixtures models, are very often used as part of speech recognition systems. Gaussian mixture models (GMM) are used in SRS to estimate the density of the probabilities of the variability of speech data due to moderately low computational cost of analysis and convergent adaptation algorithms [9, 10], in particular, the Expectancy-Maximization (EM) algorithm, the Maximum a Posteriori Probability (MAP) algorithm or Maximum Likelihood Linear Regression Maximization (MLLR) algorithm. However, the GMM has a low sensitivity to the variability of speech signal over time, which is usually compensated by detail for an adequate description of the individual features of speech, which leads to an increase in the sensitivity of the received features space to the presence in a phonogram of a speech signal a noises of the surrounding space. In their turn, the hidden Markov models (HMM) are statistical models that describe the analyzed system as a Markov process with unknown parameters [6] in order to determine the most probable state of the sequence of units of acoustic elements of speech signals based on pretrained models. For SRS, each state of the HMM is represented by different stable elements of speech (for example, the phonemes), and the time information is encoded by the permitted transitions between states. Thus, the speaker recognition using HMM is to determine for each speaker the optimal position between the sequence of the [...]

Generator modes for technological installations with variable parameters of the oscillating circuit DOI:10.15199/48.2019.04.33

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In technological installations for ultrasonic machining (USM), piezoelectric and magnetostrictive transducers (PET and SME) of electric oscillations are used in mechanical deformation of the medium with processed products as executive bodies in various technological processes. To generate electric oscillations, specialized generators (inverters) are used. Technical characteristics and operating modes of this generator are subject to special requirements. Generally, the PET is a package of piezoceramic washers with a diameter of 20 to 120 mm and a thickness of 3 to 10 mm, reinforced with metal straps. When the piezo packet is generated by electric oscillations due to the secondary piezoelectric effect, its bends occur and mechanical oscillations arise [1]. For example, in engineering technologies where ultrasonic treatment is applied, a variety of operations can be performed. Such as:  Cleaning and washing products,  Cutting, microwelding, brazing,  Shaping of parts from hard or brittle materials,  Hardening of the cutting tool,  Actuation of a percussion instrument. In technological installations, especially where percussion impacts on the tool are used, there is a sharp change of the load PET. This affects the generator operating modes. It is known [2,3] that piezoceramics possess a very high electromechanical Q-factor and its resonance characteristic is very sharp, so if the frequencies of the feeding generator and the instrument do not coincide, emergency regimes may arise. In this case, the generator will operate in modes from idle to short circuit, which is accompanied by the occurrence of either over voltages or over currents in the circuit. Formulation of the problem On the assumption of the foregoing, it is possible to determine a number of requirements for supplying PET generators capable of operating both on a regular basis and in emergency conditions:  Sinusoid[...]

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