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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Evaluation and Comparison of Beamforming Algorithms for Microphone Array Speech Processing

Allred, Daniel Jackson 11 July 2006 (has links)
Recent years have brought many new developments in the processing of speech and acoustic signals. Yet, despite this, the process of acquiring signals has gone largely unchanged. Adding spatial diversity to the repertoire of signal acquisition has long been known to offer advantages for processing signals further. The processing capabilities of mobile devices had not previously been able to handle the required computation to handle these previous streams of information. But current processing capabilities are such that the extra workload introduced by the addition of mutiple sensors on a mobile device are not over-burdensome. How these extra data streams can best be handled is still an open question. The present work deals with the examination of one type of spatial processing technique, known as beamforming. A microphone array test platform is constructed and verified through a number of beamforming agorithms. Issues related to speech acquisition through microphones arrays are discussed. The algorithms used for verification are presented in detail and compared to one another.
2

TIME REFERENCE SYSTEM OF THE ESO VERY LARGE TELESCOPE.

Lange, Werner R., Ravensbergen, Martin 11 1900 (has links)
International Telemetering Conference Proceedings / October 30-November 02, 1995 / Riviera Hotel, Las Vegas, Nevada / The necessity of supplying precise time information in large telemetry ground stations and astronomical observatories is very similar. Therefore the way of solving this problem as it is done in the Very Large Telescope of the European Southern Observatory can be easily adopted to telemetry stations and ranges, especially when fiber optics are used. The European Southern Observatory (ESO) is building a new observatory in Chile for the Very Large Telescope (VLT). This VLT consists of 4 telescopes, each of them has a primary mirror diameter of 8 meters. the control architecture is based on workstations and VMEbus computers. The VMEbus computers are distributed over the whole building and are using real time operating system. Since the availability of the Global Positioning System (GPS) the generation of highly accurate timing signals on remote locations without the use of expensive Cesium standards does not create problems any more. However, distribution of a timing signal to many computer with high accuracy is an issue. The accuracy of the commonly used IRIG B-code is not adequate if the requirements are in the 10 microseconds range. This paper presents the design of a timing system that is adopted to the VLT. An overview of the requirements of the Time Reference System (TRS) is given. These requirements have been defined on the basis of experiences with the timing system of the ESO NTT telescope. The hardware units are described. These are a Central Time Standard, a Time Distribution System and a VME Time Interface Module. The distribution is based on fiber optic transmission, using a simple digital modulation that outperforms the analog IRIG B modulation. The Time Interface Module in the computer does not only perform the timing signal decoding but contains also user-programmable timers that are synchronously clocked from the time source. Presently all units of the TRS have been tested and the series production of the distribution and the Time Interface Modules are in progress.
3

Evaluation of Crossover Displaced Left-turn (XDL) Intersections and Real-time Signal Control Strategies with Artificial Intelligence Techniques

Jagannathan, Ramanujan 12 October 2004 (has links)
Although concepts of the XDL intersection or CFI (Continuous Flow Intersection) have been around for approximately four decades, users do not yet have a simplified procedure to evaluate its traffic performance and compare it with a conventional intersection. Several studies have shown qualitative and quantitative benefits of the XDL intersection without providing accessible tools for traffic engineers and planners to estimate average control delays, and queues. Modeling was conducted on typical geometries over a wide distribution of traffic flow conditions for three different design configurations or cases using VISSIM simulations with pre-timed signal settings. Some comparisons with similar conventional designs show considerable savings in average control delay, and average queue length and increase in intersection capacity. The statistical models provide an accessible tool for a practitioner to assess average delay and average queue length for three types of XDL intersections. Pre-timed signal controller settings are provided for each of the five intersections of the XDL network. In this research, a "real-time" traffic signal control strategy is developed using genetic algorithms and neural networks to provide near-optimal traffic performance for XDL intersections. Knowing the traffic arrival pattern at an intersection in advance, it is possible to come up with the best signal control strategy for the respective scenario. Hypothetical cases of traffic arrival patterns are generated and genetic algorithms are used to come up with near-optimal signal control strategy for the respective cases. The neural network controller is then trained and tested using pairs of hypothetical traffic scenarios and corresponding signal control strategies. The developed neural network controller produces near-optimal traffic signal control strategy in "real-time" for all varieties of traffic arrival patterns. / Master of Science
4

Phase and Frequency Estimation: High-Accuracy and Low- Complexity Techniques

Liao, Yizheng 25 April 2011 (has links)
The estimation of the frequency and phase of a complex exponential in additive white Gaussian noise (AWGN) is a fundamental and well-studied problem in signal processing and communications. A variety of approaches to this problem, distinguished primarily by estimation accuracy, computational complexity, and processing latency, have been developed. One class of approaches is based on the Fast Fourier Transform (FFT) due to its connections with the maximum likelihood estimator (MLE) of frequency. This thesis compares several FFT-based approaches to the MLE in terms of their estimation accuracy and computational complexity. While FFT-based frequency estimation tends to be very accurate, the computational complexity of the FFT and the latency associated with performing these computations after the entire signal has been received can be prohibitive in some scenarios. Another class of approaches that addresses some of these shortcomings is based on linear regression of samples of the instantaneous phase of the observation. Linear- regression-based techniques have been shown to be very accurate at moderate to high signal to noise ratios and have the additional benefit of low computational complexity and low latency due to the fact that the processing can be performed as the samples arrive. These techniques, however, typically require the computation of four-quadrant arctangents, which must be approximated to retain low computational complexity. This thesis proposes a new frequency and phase estimator based on simple estimates of the zero-crossing times of the observation. An advantage of this approach is that it does not require arctangent calculations. Simulation results show that the zero-crossing frequency and phase estimator can provide high estimation accuracy, low computational complexity, and low processing latency, making it suitable for real-time applications. Accordingly, this thesis also presents a real-time implementation of the zero-crossing frequency and phase estimator in the context of a time-slotted round-trip carrier synchronization system for distributed beamforming. The experimental results show this approach can outperform a Phase Locked Loop (PLL) implementation of the same distributed beamforming system.
5

Real time extraction of ECG fiducial points using shape based detection

Darrington, John Mark January 2009 (has links)
The electrocardiograph (ECG) is a common clinical and biomedical research tool used for both diagnostic and prognostic purposes. In recent years computer aided analysis of the ECG has enabled cardiographic patterns to be found which were hitherto not apparent. Many of these analyses rely upon the segmentation of the ECG into separate time delimited waveforms. The instants delimiting these segments are called the
6

Estimação espacial da migração de consumidores residenciais para a tarifa branca em sistemas de distribuição de energia elétrica /

Cunha, Pedro Paulo. January 2018 (has links)
Orientador: Antonio Padilha Feltrin / Resumo: Neste trabalho o espaço geográfico é incorporado ao estudo da análise das potencialidades de migração de consumidores residenciais para uma nova opção tarifária: a tarifa branca. Os trabalhos avaliados no tema não incorporam a análise espacial de dados geográficos. Em geral apresentam as classes de consumo que mais se beneficiam com a adoção da nova opção tarifária e aspectos relacionados à estrutura tarifária de energia elétrica no Brasil. No entanto, o estudo das características do lugar onde pode ser mais provável a migração massiva de consumidores para a tarifa branca pode trazer informações relevantes para direcionar a atenção das distribuidoras de energia na aquisição de medidores eletrônicos e outros equipamentos para determinadas regiões da área urbana do município. Promove-se dessa forma um melhor dimensionamento do sistema elétrico. Os resultados deste trabalho são mapas de probabilidades úteis para indicar as subáreas onde há maior probabilidade de migração de consumidores residenciais para a tarifa branca. Esses mapas indicam que algumas regiões da cidade como a porção central e leste para os anos de 2018 e 2019 exibem maior probabilidade de unidades consumidoras aptas a migrarem para a tarifa branca. Portanto, há nessas regiões uma tendência de redução da demanda de ponta (ou de pico). Espera-se uma mudança de perfil de carga daqueles alimentadores que atendem regiões onde há maior quantidade de consumidores que irão migrar para a tarifa branca. O espaço é incorp... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: In this work the geographic space is incorporated to the study of the analysis of the potentialities of migration of residential consumers for a new tariff option: the white tariff. The works evaluated in the theme do not incorporate the spatial analysis of geographic data. In general, they present the classes of consumption that most benefit from the adoption of the new tariff option and aspects related to the tariff structure of electric energy in Brazil. However, the study of the characteristics of the place where the massive migration of consumers to the white tariff may be most likely to bring relevant information to direct the attention of energy distributors in the acquisition of electronic meters and other equipment for certain regions of the urban area of the County. In this way, a better design of the electrical system is promoted. The results of this work are useful probability maps to indicate the subareas where there is a greater probability of migration of residential consumers to the white tariff. These maps indicate that some regions of the city such as the central and eastern portions for the years 2018 and 2019 are more likely to be consumer units able to migrate to the white tariff. Therefore, there is a tendency in these regions to reduce the peak (or peak) demand. A load profile change is expected from those feeders serving regions where there are more consumers who will migrate to the white tariff. The space is incorporated in this work through technique... (Complete abstract click electronic access below) / Mestre
7

Detekce a prostorová lokalizace částečných výbojů ve výkonových transformátorech metodou UHF / Partial Discharges Detection and Spatial Localization in High Power Transformers Using UHF Method

Čáp, Martin January 2017 (has links)
The thesis discusses the design and experimental verification of a new method for detecting partial discharges in oil-cooled high-power transformers, emphasizing the origin of the measured signal from the outer and inner regions of the transformer tank. The detection and spatial localization of partial discharges utilizes UHF (Ultra High Frequency) electromagnetic signal measurement. The UHF partial discharge detection method, also referred as UHF PD, is one of the most advanced techniques for the accurate spatial localization of the signal source position. The focus of the thesis lies in the development of technical and software solutions for the separation of partial discharge signals originating from the internal space of the transformer and the spurious signals from the connection lines. The proposed technical and program solutions constitute a signal discriminatory method. The precise and repeatable diagnostics of the transformer state are guaranteed by observing the measurement methodology and special setting of the diagnostic system. The functionality of the signal discriminatory method was verified during real measurement of the oil-cooled power transformers at the Dukovany nuclear power plant in operation. The output of the designed methodology is to set up a calibration procedure and follow-up steps to ensure objective, repeatable, and comparable measurements for the purposes of regular predictive maintenance in transformers.
8

Návrh algoritmů číslicového zpracování signálů pro simulaci kytarových zesilovačů založených na obvodové analýze analogových prototypů / Design of Algorithms of Digital Audio Processing for Simulation of Guitar Combo Based on Circuit Analysis of Analogue Prototypes

Mačák, Jaromír January 2008 (has links)
This work deals with computer simulation of a guitar combo. The complete simulation is divided into separate blocks and then transfer characteristics and frequency responses of each block are obtained from a circuit analysis of analogue prototype. After their aproximation, the transfer characteristics are implemented as waveshapers and frequency responses are simulated using digital filters designed according to their analogue prototypes. Designed algorithms are implemented as plug-in mudule in language C++.
9

Digitální zvukový efekt typu reverb využívající konvoluci signálu s impulsní charakteristikou poslechového prostoru / Reverb Digital audio effect based on convolution with impulse response of acoustic room

Tichý, Vladimír January 2009 (has links)
This work deals with a computer simulation of an acoustic room using its impulse response. Two different approaches to the simulation are described with their pros and cons and then the work is focused on the physical approach, which uses room’s impulse response during the simulation. Several methods for the extraction of the impulse response of the acoustic room are mentioned with their conditions of use. The detailed description of various algorithms for a real time convolution computing is followed by the cost analysis of frequency domain block convolution algorithms. Several algorithms are chosen, implemented and tested in Matlab environment. Then the most effective of them is chosen to be implemented in VST technology as the plug in module for real time room simulation.
10

Generování pásmově omezených číslicových zvukových signálů v reálném čase / Real-Time Generation of Band-Limited Digital Audio Signals

Maule, Petr January 2010 (has links)
Master’s thesis deals with the generation of digital audio signals with band-limited frequency spectrum, i.e. without the aliasing distortion. Various methods of generating band-limited rectangular, triangular, and sawtooth waveforms are described in the theoretical part. The described methods are programmed in the Matlab programming environment and compared in terms of real-time parameter changes, such as duty cycle change of rectangular waveform or continuous change of frequency. The main part of the thesis describes implementation of methods of successive integration of band-limited impulse train and method of differentiated parabolic waveforms in C++ language. The implemented methods were integrated into a plug-in of VST technology that generates an audio signal in real time. The implemented methods are compared in terms of computational complexity and distortion of the generated signal.

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