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 20 for “"harmonic components"”.
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Evaluation of Active Capacitor Banks for Floating H-bridge Power Modules
… fluctuation, due to the presence of reactive harmonic components. Utilizing passive capacitors, as done in traditional methods, helps reduce the DC-bus voltage ripple but makes the system bulky. An active capacitor can be integrated with the floating H-bridge power modules to remove the effect …
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Smart grid analysis with particular references to power quality and load forecast
… The proposed algorithm is able to identify all harmonic components including integer, non-integer and sub-harmonics. Comparing with DFT, the proposed algorithm achieves exact estimation of the harmonic frequency. Thirdly, reports on the development of a WT-based dynamic waveform reconstruction …
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Novel methods for enhancing accuracy and stability of power hardware-in-the-loop simulations
… well as time delay dynamics within the different components are reviewed. As a result, variable time delay has been identified within these configurations and mitigation techniques for the time delay and its variability are presented.;Furthermore, a time delay compensation scheme using Sliding …
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Advanced Power Sharing Scheme under Unbalanced and Nonlinear Loads in an Islanding Microgrid
Active, unbalanced, and harmonic power sharing inaccurately between distributed generators (DGs) and voltage quality problems are critical issues under unbalanced and nonlinear loads in the micro grids. Thus, an advanced power sharing scheme with unbalanced and harmonic loads in islanding micro …
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Aspects of magnetisation and iron loss characteristics in switched-reluctance and permanent-magnet machines
… are shown to increase significantly when higher harmonic components are introduced to the flux density waveform. The difficulties in modelling the nonlinear iron loss characteristics of electrical steels are considered.
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Vortex-induced motions of marine risers : straked force database extraction & transient response analysis
… oscillation, often accompanied by large 3rd harmonic components in the acceleration and strain signals, increased correlation length, stable riser trajectories, and monochromatic traveling or standing waves.
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Millisecond oscillations during thermonuclear X-ray bursts
… produce oscillations that are very sinusoidal - harmonic components have amplitudes that are less than 5-10% of those of the main signals. This suggests that the patterns are very symmetric. The types of bursts that exhibit oscillations are correlated with the pulsation frequency.
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Theoretical prediction of counter-rotating propeller noise
… propeller. We start by deriving formulae for the harmonic components of the far acoustic field generated by the thickness and steady loading noise sources. Excellent agreement is shown between theory and measurements. Asymptotic approximation techniques are described which enable us to simplify …
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Design and implementation of three-phase four-wire active filters
… of more stringent requirements regarding harmonic current generation, as are found in standards such IEEE-519. Passive filters have been used to limit the flow of harmonic currents in distribution systems. However, these tend to be bulky and the design is complex, particularly if the …
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Influence of higher time harmonics on the electrical and mechanical performance of an inverter-fed squirrel cage induction motor
… non-sinusoidal and polluted with higher time harmonic components. The higher time harmonics affect the electrical and mechanical performance significantly, and adverse effects are investigated. Literature on the effect of higher time harmonics is reviewed. Recommendations referring to various …
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Design and Linearization of Energy Efficiency Power Amplifier in Nonlinear OFDM Transmitter for LTE-5G Applications. Simulation and measurements of energy efficiency power amplifier in the presence of nonlinear OFDM transmitter system and digital predistortion based on Hammerstein-Wiener method
… investigation on the fundamental and harmonic components of class F RF power amplifier using a load-pull approach to realise an optimum load impedance and the matching network is presented. The frequency bandwidth for both amplifiers was allocated to operate in the 2.620-2.690 GHz of …
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Duality derived topological model of single phase four limb transformers for GIC and DC bias studies
… for power system operators since they can cause harmonics, transformer heating, mal-operation of protection relays, generator heating and vibration, and consume a large reactive power that can cause voltage collapse. Network studies of slow transient phenomena such as transformer half-wave …
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The Music Muse
… their voices by showing them the individual components of their voices that combine to produce timbre. In paintings, many colors are combined to produce different hues and shades of color. The individual colors that make up the hue are difficult to distinguish. Similarly in music, harmonics …
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Energy efficiency analysis of converter-fed induction motors
… is the accurate determination of additional harmonic losses due to the PWM voltages and currents. Although the recently introduced IEC 60034-2-3 Technical Specification has proposed a method of determining these losses through experimental testing, the approach is still undergoing validation. …
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Deep structure ultrasound imaging using fundamental and third harmonic coded excitation techniques
… Golay coding with fundamental and third harmonic 1, 3 chirps with resolution enhancement compression (REC) and frequency compounding, increases the axial resolution, lateral resolution, penetration depth and the contrast-to-noise ratio (CNR) for an ultrasonic imaging system. The thickness …
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The influence of high harmonic force on fatigue life and its prediction via coupled inline-crossflow VIV modeling
… to the flow direction) and were purely harmonic ones with only one major frequency close to the Strouhal frequency (a dimensionless representative of the frequency of vortex shedding). The study of inline motion of long flexible cylinders caused by VIV has been long neglected due to its …
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Efektový zesilovač pro elektrickou kytaru
… práce v první části stručně popisuje vnímání harmonických frekvenčních složek lidským uchem, v druhé části se zaměřuje na účel kytarových efektů a přehled obvyklých typů, se kterými se lze na trhu setkat. V třetí části následuje bližší seznámení s principem funkce efektů vybraných k realizaci, …
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Trumpet Mouthpiece Backbores: An Investigation of Interior Volume and Timbre
… was done with the same equipment and method. The harmonic components, or spectrum, of the trumpet sound for each test was analyzed to describe timbre. An oscilloscope was used to convert the sound waves into harmonic spectrums. In this study, the method of describing timbre uses the harmonic …
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Active Source Management to Maintain High Efficiency in Resonant Conversion over Wide Load Range
… ensuring sufficient bandwidth, and allowing rich harmonic content in the input current. Of particular importance are fundamental and second harmonic components since they influence synchronization of the zero-crossing of the output voltage and the turn-on of the switches. The synchronization …
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Design, optimization and analysis techniques of non-linear devices based on graphene or highly ordered pyrolytic graphite for terahertz system applications
… of passive devices with non-linear harmonic content. These devices are based on frequency multiplication and frequency mixing on mono- and multi-layer graphene films which are used for the generation and/or detection of submillimeter wave/ low THz band signals. The desired frequency …