Three-phase voltage source inverters are increasingly employed in power systems and industrial applications. Various pulse width modulation strategies have been applied to control the voltage source inverters. This dissertation presents a hybrid 2D-3D space vector modulation algorithm for three-phase voltage source inverters with both three-wire and four-wire topologies. The voltage magnitude and phase angle of the inverters fundamental output phase voltage are precisely controlled under either balanced or unbalanced load conditions, and hence, the space vector algorithm offers synchronization controllability over generation control in distributed generation systems. The numerical efficiency and simplicity of the proposed algorithm are validated through conducting MATLAB/Simulink simulations and hardware experiments. Mathematical description and harmonic analyses of output phase voltages of three-phase voltage source inverter which employs a hybrid 2D-3D SVM are presented in this dissertation. Explicit time domain representation of the harmonic components in addition to the total harmonic distortion of the output phase voltages are given in terms of system and switching parameters. The dissertation also investigates the harmonic characteristics and low total harmonic distortion performance against the linearity of modulation region which helps in the harmonic performance and design studies of such inverters employing the hybrid 2D-3D SVM. Experimental results are used to validate these analyses. In addition, the performance and the harmonic contents of the inverter output phase voltage when applying the proposed hybrid 2D-3D SVM are compared to that obtained from conventional 2D SVM and 3D SVM. As a result, the proposed new algorithm shows advantages in terms of low total harmonic distortion and reduced harmonic contents in both three-wire and four-wire systems.

Non-native scale insects can be economically and ecologically important pests of urban forests. Crapemyrtle bark scale (CMBS), Acanthococcus lagerstroemiae Kuwana (Hemiptera: Eriococcidae), is a scale that causes declines in plant vigor for a popular ornamental tree in the southeastern United States, crapemyrtle (Lagerstroemia spp.). CMBS has spread rapidly throughout the Southeast and, more recently, into the Middle Atlantic. Despite problems associated with CMBS, important aspects of its ecology, such as the role of propagule pressure in establishment and the relative importance of mechanisms for between-tree dispersal, are not well-understood. We used field and laboratory studies to investigate these aspects of CMBS population ecology, finding that just one female CMBS ovisac can establish new populations and that nymphs are dislodged at low wind speeds (7 m/s) from crapemyrtle twigs. Our results highlight the importance of thorough phytosanitation practices in crapemyrtle nurseries and provide evidence for wind-mediated and phoretic dispersal by CMBS.

Support vector machines are a relatively new approach for creating classifiers that have become increasingly popular in the machine learning community. They present several advantages over other methods like neural networks in areas like training speed, convergence, complexity control of the classifier, as well as a stronger mathematical background based on optimization and statistical learning theory. This thesis deals with the problem of model selection with support vector machines, that is, the problem of finding the optimal parameters that will improve the performance of the algorithm. It is shown that genetic algorithms provide an effective way to find the optimal parameters for support vector machines. The proposed algorithm is compared with a backpropagation Neural Network in a dataset that represents individual models for electronic commerce.

Dirofilaria immitis, commonly known as dog heartworm, is a dangerous filarial nematode that is transmitted by a mosquito vector. Although this parasite is historically localized to regions closer to the equator, the last few decades have experienced an increase in the amount of dog heartworm cases in Northern California, most notably in Lake and San Joaquin Counties. The primary vector of D. immitis in Northern California is Aedes sierrensis, but it is not prevalent enough in some counties to explain the increase in infections. Because of this, more prevalent and abundant species should be assessed for their ability to transmit heartworm. Culex pipiens complex (wild) and Culiseta incidens (laboratory-raised colonies) were chosen as potential vectors during this study due to their ability to meet several key vector criteria, their relative abundance in the areas of interest, and the fact that they habitually take bloodmeals from domestic dogs. Additionally, Ae. sierrensis colonies were used in this study, based on previous knowledge that they are highly competent vectors. Female mosquitoes were infected with 2.5, 5, or 10 mff/ul of D. immitis-infected blood, and decapitated at 15, 18, and 21 days post-infection. Mosquitoes were subsequently tested via qPCR for the presence and relative quantification of D. immitis DNA. We found that Ae. sierrensis and Cx. pipiens complex were both able to support the development of D. immitis to its infective stage, while Cs. incidens was not a competent vector. We also concluded that including a standard curve of known amounts of D. immitis larvae makes it possible to approximate the intensity of the infection in the mosquito. The identification of these important vectors, and the ability to assess infection intensity, may be helpful in the continued vector control efforts in Northern California and beyond.

Banded iron formations (BIFs) are iron oxide- and silica-rich chemical sedimentary rocks and the principal source of high-grade (HG) iron ore. Magnetic survey methods are commonly applied in the exploration for BIF-hosted iron ore deposits but the interpretation of total magnetic intensity (TMI) data is often complicated by the presence of strong remanent magnetization and anisotropy of magnetic susceptibility (AMS). This study evaluated a tri-axial fluxgate vector magnetometer system for ground-based high-resolution mapping of BIF-hosted HG iron ore deposits at a 16 ha site near Mary River, Baffin Island. Magnetometer orientation was measured using a MEMS (Micro Electro-Mechanical System) accelerometer and dual D-GPS receivers. 12-oriented block samples were collected for analysis of rock magnetic properties and supplemented with outcrop measurements using a hand-held susceptibility probe. The large (3 Gauss) dynamic range of the tri-axial vector magnetometer permitted mapping of HG magnetite ore zones, with TMI in excess of 400,000 nT. A 20 m-wide W-E trending HG zone and a narrow (<10 m) BIF zone were identified in RMV maps with distinctive dipole signatures. Within the HG zone a northwest-southeast oriented magnetic fabric was defined by linear magnetic lows that offset the strike of the HG ore zone and were interpreted as brittle faults or shear zones. The RMV orientation indicated the presence of strong bedding parallel magnetization, while its signal amplitude showed a wide variation between ore types and provided basis for ore grade differentiation. Paleomagnetic measurements revealed high Q ratios for hematite ores and strong AMS for BIF. The results from Mary River demonstrate that remanence and AMS effects are important in BIF-hosted iron ores and cannot be neglected in magnetic interpretation and inversion modelling of magnetic source bodies. / Thesis / Master of Science (MSc)

<p> An investigation has been made of the microwave reflections from the surface of a semiconducting medium with complex permittivity (^ε = εrεo -jσ/ω) at the open end of an empty rectangular waveguide. The approximate and exact solutions of the reflection coefficients at the surfaces of both finite and semi-infinite media have been found as a function of the complex permittivity of the medium. The computations of the reflection coefficients are made at the 10 and 35 GHz ranges. Measurements, which confirm these calculations, have been performed with n-type germanium, selectron, and air at the open end of a rectangular waveguide using a reflection type microwave bridge. The investigation has shown that it is possible to devise a convenient method of measuring the conductivity and dielectric constant of semiconductors.</p> <p> The theory of operation of the microwave reflection bridge together with the setting-up (matching) procedure of a practical form of the bridge has been presented. A method is also described for the correction of the measurement error which arises from the scattering coefficients at the input ports of the precision attenuator.</p> <p> A theoretical and experimental study has also been made of the small- signal microwave conductivity of n-type germanium at room temperature in the presence of a high electric field, directed at an angle θ to the microwave field. The study has shown that at frequencies such as 10 GHz, the microwave conductivity becomes anisotropic with respect to the direction of the d.c. field vector. Measurements are made on an 11.4 ohm cm, n-type germanium sample at 9.381 GHz with applied electric fields up to 1.8 KV/cm for θ = 0°, 40°, and 90°. The ''open-end-waveguide measuring technique", which allows the angle between the microwave and d.c. field vectors to be varied, was employed to measure the microwave conductivity. The results of measurements which agree with predictions, confirm the feasibility of operation of a new microwave device based on the anisotropic effect.</p> / Thesis / Doctor of Philosophy (PhD)

There is a limited amount of literature regarding spillover effects on inflation. The previous literature is focused on a small number of countries, and on shocks coming from demand and supply. The objective of this thesis is to investigate how a change in the European Central Bank (ECB) policy rate affects Swedish inflation in the short and long run. To this end, this thesisestimates a cointegrated vector autoregressive (CVAR) model using data for the period from 2000 to 2022. The results show that a change in the ECB rate does not have statistically significant effect on the Swedish inflation in the short run, but has statistically significant effect in the long run. The long run results do also show that an increase in the ECB rate have a positive effect on the Swedish central bank’s policy rate.

The null result of December 2004 Sub-threshold photoproduction of J/$psi$ experiment has motivated this thesis. This monte-carlo predicts the cross-section for sub-threshold photoproduction process and provides an insight on the cross-section range of these processess. The experiment was also conducted as a calibration run for Omega and Eta mesons for the verification of correctness of experimental procedure. The results from this experiment are compared with the monte-carlo simulation for the number of omega meson events. This is primarily done as the models for photoproduction of omega meson are well tested. The monte-carlo provides satisfactory results for the photoproduction models and with a crude a spectrometer model predicts the number of events which are off by a factor less than two. A refined model from Jefferson lab will eliminate this discrepancy.

The scientific community has employed multiple methods to analyze and describe the jet noise emanating from the turbulent exhaust flow from modern military aircraft engines, with the goal that better characterization of the sound radiation will improve noise reduction efforts. This thesis utilizes three different approaches to characterize the noise source region from a static F-22A Raptor. First, the energy flow field along planes near the aircraft and along an arc is measured using a multidimensional vector intensity probe. The resulting vector intensity maps give a clear indication of the directionality of the noise as a function of frequency at different engine conditions. A straightforward ray-tracing method show the utility of vector intensity measurements in source characterization by estimating the region from which the loudest portions of sound are emanating. Second, intensity reconstructions from near-field acoustical holography (NAH) provide an estimate of the three-dimensional radiated energy flow field. The sound field is shown to be dominated by mutually incoherent radiation lobes, which can be partially isolated by a partial decomposition method. Lastly, a wavepacket source model is optimized in light of amplitude-based NAH reconstructions near the jet axis. The wavepacket model successfully fits the NAH-reconstructed partial fields, especially at frequencies above 50 Hz, indicating that the source may be modeled by multiple wave packets at each frequency.

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