This study was aimed at determining whether the digital volume pulse waveform using the Pulse Sensor can be used to extract features related to arterial compliance. The Pulse Sensor, a low-cost photoplethysmograph, measures green light reflection in the finger and generates output, which is indicative of blood flow and can be read by the low-cost Arduino UNO™. The Pulse Sensor code was modified to increase the sampling frequency and to capture the data in a file, which is subsequently used for waveform analysis using programs written in the R system. Waveforms were obtained using the Pulse Sensor during two 30-s periods of seated rest, in each of 44 participants, who were between the ages of 20 and 80 years. For each cardiac cycle, the first four derivatives of the waveform were calculated and low-pass filtered by convolution before every differentiation step. The program was written to extract 19 features from the pulse waveform and its derivatives. These features were selected from those that have been reported to relate to the physiopathology of hemodynamics. Results indicate that subtle features of the pulse waveform can be calculated from the fourth derivative. Feature misidentification occurred in cases of saturation or low voltage and resulted in outliers; therefore, trimmed means of the features were calculated by automatically discarding the outliers. There was a high efficiency of extraction for most features. Significant relationships were found between several of the features and age, and systolic, diastolic, and mean arterial blood pressure, suggesting that these features might be employed to predict arterial compliance. Further improvements in experimental design could lead to a more detailed evaluation of the Pulse Sensor with respect to its capability to predict factors related to arterial compliance.

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Complex optical pulse shapes are typically generated from ultrashort laser pulses by manipulating the optical spectrum of the input pulses. This generates complex but periodic time-domain waveforms. Optical Arbitrary Waveform Generation (OAWG) builds on the techniques of ultrashort pulse-shaping, with the goal of making non-periodic, truly arbitrary optical waveforms. Some applications of OAWG are coherently controlling chemical reactions on a femtosecond time scale, improving the performance of LADAR systems, high-capacity optical telecommunications and ultra wideband signals processing. In this work, an array of Vertical Cavity Surface Emitting Lasers (VCSELs) are used as modulators, by injection-locking each VCSEL to an individual combline from an optical frequency comb source. Injection-locking ensures that the VCSELs' emission is phase coherent with the input combline, and modulating its current modulates mainly the output optical phase. The multi-GHz modulation bandwidth of VCSELs updates the output optical pulse shape on a pulse-to-pulse time scale, which is an important step towards true OAWG. In comparison, it is about a million times faster than the liquid-crystal modulator arrays typically used for pulse shaping! Novel components and subsystems of Optical Arbitrary Waveform Generation (OAWG) are developed and demonstrated in this work. They include: 1. Modulators An array of VCSELs is packaged and characterized for use as a modulator for rapid?update pulse?shaping at GHz rates. The amplitude and phase modulation characteristics of an injection-locked VCSEL are simultaneously measured at GHz modulation rates. 2. Optical Frequency Comb Sources An actively mode-locked semiconductor laser was assembled, with a 12.5 GHz repetition rate, ~ 200 individually resolvable comblines directly out of the laser, and high frequency stability. In addition, optical frequency comb sources are generated by modulation of a single frequency laser. 3. High-resolution optical spectral demultiplexers The demultiplexers are implemented using bulk optics, and are used to spatially resolve individual optical comblines onto the modulator array. 4. Optical waveform measurement techniques Several techniques are used to measure generated waveforms, especially for spectral phase measurements, including multi-heterodyne phase retrieval. In addition, an architecture for discriminating between ultrashort encoded optical pulses with record high sensitivity is demonstrated.

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Voltage source inverters (VSI) are popular in variable speed induction motor drive applications. Pulse width modulation (PWM) is employed to achieve variable voltage variable frequency output from a fixed DC bus voltage. The modulation method greatly influences the harmonic distortion in line current and the inverter switching loss. This thesis evaluates a few space vectorbased PWM techniques which reduce the harmonic distortion and/or the inverter switching loss, compared to conventional space vector PWM (CSVPWM), at a given average switching frequency. In space vector-based PWM, the average voltage vector applied over a sub-cycle equals the commanded reference vector, thereby maintaining voltsecond balance. The given average vector can be realized by applying the voltage vectors of the inverter in different sequences. CSVPWM employs a switching sequence in which all the phases switch once in a sub-cycle. Sequences, in which a phase is clamped, while the other two phases switch once in a sub-cycle have been reported in literature. Further, certain special switching sequences have also been reported recently. These special sequences involve switching a phase twice, while switching the second phase once and clamping the third phase in a sub-cycle. This work investigates the use of such special switching sequences to reduce line current distortion and inverter switching loss in an induction motor drive. The influence of various switching sequences on line current ripple and inverter switching loss is discussed in the thesis. Comparison of the sequences in terms of switching loss leads to a hybrid PWM technique, which deploys the best sequence to reduce switching loss under a given operating condition. This technique is referred to as minimum switching loss PWM (MSLPWM). Further, a procedure for design of hybrid PWM techniques to achieve reduced line current distortion as well as inverter switching loss is elaborated. Four such specially designed hybrid PWM techniques are discussed. Analytical methods are presented for the evaluation of total RMS harmonic distortion factor of line current and inverter switching loss corresponding to different PWM techniques. The MSLPWM and the hybrid PWM techniques are evaluated analytically in terms of harmonic distortion and switching loss. It is observed that the switching loss corresponding to MSLPWM is considerably less than that with CSVPWM over the entire range of power factor. The reduction in switching loss with MSLPWM is as high as 36% at high power factors close to unity, while it is not less than 22% at power factors close to zero. MSLPWM also reduces the harmonic distortion for power factors close to unity at high modulation indices. Compared to CSVPWM, the hybrid PWM techniques result in a maximum reduction of about 40% in the harmonic distortion at fundamental frequencies close to 50Hz, and about 30% reduction in switching loss at power factors close to unity. The various PWM techniques are tested on a constant V /f induction motor drive with a digital control platform based on ALTERA Cyclone II field programmable gate array (FPGA) device. With a 10kVA IGBT based inverter feeding a 2.2kW, 415V, 50Hz, three-phase induction motor, the total RMS harmonic distortion factor of line current (IT HD) is measured at different fundamental frequencies for the various PWM techniques. The average switching frequency is 2.44kHz. The measured values of IT HD show a reduction in distortion with the hybrid PWM techniques over CSVPWM at high speeds of the drive. The relative values of IT HD corresponding to different PWM techniques agree with the theoretical predictions. With the 10kVA IGBT based inverter feeding a 6kW, 400V, 50Hz, 4pole, three-phase induction motor, the switching losses corresponding to CSVPWM and MSLPWM are evaluated and compared. This is done by measuring the steady state temperature rise of the heat sink over the ambient for the two techniques under different conditions. The thermal measurements are carried out at different loads with power factor ranging from 0.14 to 0.77. The measurements are also carried out at different fundamental frequencies (or modulation indices). Further, to separate conduction (constant) losses and switching (variable) losses, the heat sink temperatures are measured at two different switching frequencies, namely 2.44kHz and 4.88kHz. It is observed that the temperature rise due to MSLPWM is less than that due to CSVPWM consistently under various operating conditions. The thermal measurements confirm the theoretical prediction of reduction in switching loss with MSLPWM. Measurements of heat sink temperature rise corresponding to CSVPWM, MSLPWM and the hybrid PWM techniques are carried out at a higher power factor of 0.98 (lag) with the inverter feeding an RL load (instead of an induction motor). The hybrid PWM and MSLPWM result in lower switching losses as indicated by the reduction in temperature rise.

This work deals with the analysis of pulse modulation issues, work is divided into six chapters. The first chapter of the thesis deals with pulse modulations as a whole. It explains the concept of modulation, the distinction between analog and digital modulation, and there is the basic classification of pulse modulation done. The second chapter focuses on the issue of non-quantized pulse modulation. For each modulation belonging to this group is verbally and graphically explains the principle of its activities. In the third chapter, which is similar to the second chapter, the work focuses on quantized pulse modulation. Again, each of these modulations explained its basic principle. It is also in this chapter outlines the design models in Matlab-Simulink. The fourth chapter presents calculations and tables with calculated values needed for simulations. In the fifth chapter, a comparison waveforms. It contains a discussion about the dependence of modulation on their parameters, parameters of the input signal and the sampling frequency. In the final sixth chapter deals with the early design concepts and detailed diagrams for the production of demonstration products.

Tato disertační práce je zaměřena na analýzu řečového signálu za učelem detekce nemocí ovlivňujících strukturu hlasových orgánů, obzvláště těch, které mění strukturální character hlasivek. Poskytnut je přehled současných technik. Dále jsou popsány zdroje použitých nahrávek pro zdravé a nemocné mlučí. Hlavním učelem této disertační práce je popsat vypočetní postup k odhadu parametrů modelu hlasového zdroje, které umožní následnou detekci a klasifikaci nemocí hlasivek. Poskytujeme detailní popis analýzy řečových signálů, které mohou být odvozeny z parametrických modelů hlasivek.

A voltage source inverter is commonly used to supply a variable frequency variable voltage to a three phase induction motor in a variable speed application. A suitable pulse width modulation (PWM) technique is employed to obtain the required output voltage in the line side of the inverter. Real-time methods for PWM generation can be broadly classified into triangle comparison based PWM (TCPWM) and space vector based PWM (SVPWM). In TCPWM methods such as sine-triangle PWM, three phase reference modulating signals are compared against a common triangular carrier to generate the PWM signals for the three phases. In SVPWM methods, a revolving reference voltage vector is provided as voltage reference instead of three phase modulating waves. The magnitude and frequency of the fundamental component in the line side are controlled by the magnitude and frequency, respectively, of the reference vector. The fundamental line side voltage is proportional to the reference magnitude during linear modulation. With sine-triangle PWM, the highest possible peak phase fundamental voltage is 0.5Vdc, where Vdc is the DC bus voltage, in the linear modulation zone. With techniques such as third harmonic injection PWM and space vector based PWM, the peak phase fundamental voltage can be as high as (formula) (i.e., 0:577Vdc)during linear modulation. To increase the line side voltage further, the operation of the VSI must be extended into the overmodulation region. The overmodulation region extends upto the six-step mode, which gives the highest possible ac voltage for a given (formula). In TCPWM based methods, increasing the reference magnitude beyond a certain level leads to pulse dropping, and gradually leads to six-step operation. However, in SVPWM methods, an overmodulation algorithm is required for controlling the line-side voltage during overmodulation and to achieve a smooth transition from PWM to six-step mode. Numerous overmodulation algorithms have been proposed in the literature for space vector modulated inverter. A well known algorithm among these divides the overmodulation zone into two zones, namely zone-I and zone-II. This is termed as the 'existing overmodulation algorithm' here. This algorithm is modified in the present work to reduce computational burden without much increase in the line current distortion. During overmodulation, the fundamental line side voltage and the reference magnitude are not proportional, which is undesirable from the control point of view. The present work ensures a linear relationship between the two. Apart from the fundamental component, the inverter output voltage mainly consists of harmonic components at high frequencies (around switching frequency and the integral multiples) during linear modulation. However, during overmodulation, low order harmonic components such as 5th, 7th, 11th, 13th etc., are also present in the output voltage. These low order harmonic voltages lead to low order harmonic currents in the motor. The sum of the lower order harmonic currents is termed as 'lower order current ripple'. The present thesis proposes a method for estimation of lower order current ripple in real-time. In closed loop current control, the motor current is fed back to the current controller. During overmodulation, the motor current contains low order harmonics, which appear in the current error fed to the controller. These harmonic currents are amplified by the current error amplifier deteriorating the performance of the drive. It is possible to filter the lower order harmonic currents before being fed back. However, filtering introduces delay in the current loop, and reduces the bandwidth even during linear modulation. In the present work, the estimated lower order current ripple is subtracted from the measured current before the latter is fed back to the controller. The estimation of lower order current ripple and the proposed current control are verified through simulation using MATLAB/SIMULINK and also experimentally on a laboratory prototype. The experimental setup comprises of a field programmable gate arrays (FPGA) based digital controller, an IGBT based inverter and a four-pole squirrel cage induction motor. (Pl refer the original document for formula)

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