Spatial and Temporal Variations in Population Dynamics of few Key Rocky Intertidal Macrofauna at Anthropogenically Influenced Intertidal shoreline

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Comparison of voltage regulation between SST and conventional transformers in high penetration PV power systems

Solid state transformers (SST) are power electronic transformers combined with high-frequency conventional transformers and control circuitry capable of delivering high performance and flexible power control capabilities. This thesis focuses on analyzing the performance of SSTs in a distribution system with photovoltaic (PV) injection. In order to validate the performance of SSTs, average value models are used on the IEEE 34 bus distribution feeder network scaled to 12.47 kV. SST voltage profiles on the load side are analyzed and the unity power factor capabilities are demonstrated. This is followed by the study of voltage profiles on the primary side of the SST. Additionally, distributed energy resources such as PV systems tend to cause power quality issues which are handled using the SST\u27s volt-var control capabilities. In this case, both AC and DC side integration of PV systems in SST is demonstrated. DC side integration is one of the advantages of this type of solid state device. To compare this system to a conventional distribution system, the IEEE 34 bus system with similar load and PV injection profiles is built using conventional single-phase distribution transformers. By comparing the results of the SST (with AC and DC side PV integration) with a conventional transformer, the performance of the SST can be reviewed. To provide a complete analysis, voltage regulators are redesigned for the scaled IEEE 34 distribution feeder network using PSCAD while mounting conventional transformers, and its comparison is provided. Further, the impacts and performance of SST with PV penetration greater than 100% is studied and its results are presented and contrasted with conventional transformers --Abstract, page iii

Experimental and computational analysis of thermosyphon based water heaters

Storage type electric water heaters are one of the most commonly found type of heaters in households today. Due to energy costs and limited generation capacity, there is a need for improving the efficiency of such water heaters. The efficiency of water heating systems have impact both at the household and at the national level, because of their sheer numbers. Efficient water heaters lead to lower utility bills for the consumer and also reduced demand on the grid supplying electrical power to such households. This leads to a reduction in the amount of fuel used in generating electrical power and potentially, greater reliance on more efficient baseload generating capacity. This thesis, investigates the performance of a novel storage type water heater with electric resistance heating elements and quantifies improvements to the First Hour Rating at no loss of Energy Factor. The modified storage type water heater utilizes an internal thermosyphon assembly to avoid large scale internal thermal mixing. First Hour Rating and Energy Factor Rating have been measured for a system configured in the conventional form and in the thermosyphon form. The introduction of a thermosyphon assembly into the storage volume significantly improves the First Hour Rating, by an amount equal to nearly 20%. Computational analysis of the thermosyphon tube is carried out using ANSYS FLUENT. The velocity profiles and skin friction coefficients are computed at different sections of the tube to identify the different flow regimes and pressure drops across the specific sections of the assembly. --Abstract, page iii

Friction stir form welding of aluminum structures

The objective of this work was to demonstrate the applicability of friction stir welding (FSW) technology in the automotive industry. Increasing fuel prices, stringent safety and emission norms are continuously striving automakers to make lightweight, fuel efficient vehicles. Automotive engineers are researching for alternate materials in order to meet weight savings targets. Use of aluminum in place of steel in a car has been increasing for making lightweight vehicles. Conventional welding and spot welding are used as preferred joining methods by the automotive industry. However, if aluminum is used in place of steel alternate joining methods are to be researched. Due to the problems associated with the joining of aluminum with conventional welding methods, use of aluminum has been limited. Substantial amount of research has been done for the development of friction stir welding for aluminum. Joints made in aluminum using the FSW method exhibit better mechanical properties, improved fatigue life and less processing problems. This work further analyzes the scope of the FSW method for the automotive industry. Welding of various shapes commonly used in a car is considered here. The first literature covers the FSW of partial penetration butt welds for rectangular section aluminum tubes. Mechanical property determination for these welds was also performed. The second paper demonstrates entire vehicle design considering FSW as a joining process. Finite element analysis was done for the analysis of vehicle frame performance --Abstract, page iv

Monitoring of rail/wheel interaction using acoustic emission

The work presented in this thesis is related to the condition monitoring of rail-wheel interaction using Acoustic Emission (AE), the principle being that both normal and abnormal rolling give rise to AE, features of which are related to the mechanical intensity of the interaction and hence the stress range (or stress intensity factor range) to which sections of track is being exposed. Most of the work was carried out on a model wheel running on a model circular track, which was first characterised using a simulated source before studying the wave propagation from a continuously moving (wheel) source. Using a number of sensor arrays placed on the track, primary wave propagation characteristics such as wave speeds and attenuation coefficients and also secondary wave propagation characteristics such as reflection and transmission from and through the joint. A high speed camera was used to confirm, that wheel slip does not occur at the wheel speeds and loads of interest. A simple analytical model was derived using the measured wave propagation characteristics which describes the expected AE recorded at a track-mounted sensor as the wheel approaches and recedes. Using the analytical model, the effect of increasing wheel speed and axle load on the normal rolling signal was measured. Wheel rattling was observed, particularly at lower wheel speeds and loads, and this was eliminated in some trails by introducing a spacer. The effect of minor track defects and wheel flange rubbing on the track was also studied, where the comparison of the expected normal running signal with excursions above background allowed the locations of track defects to be identified. Finally, a set of experiments were carried out with simulated wheel defects. The signals were analysed using the principle of demodulated frequency resonance and matching to the expected pulse train spectra. . The findings of the work, along with a limited set of field tests on actual train-track interactions allows recommendations to be made for the deployment of sensors for cumulative damage monitoring on critical areas of track

Automating database curation with workflow technology

The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file.Title from PDF of title page (University of Missouri--Columbia, viewed February 12, 2010).Thesis advisor: Dr. Toni Kazic.Includes bibliographical references.M.S. University of Missouri--Columbia 2005.Dissertations, Academic -- University of Missouri--Columbia -- Computer science.Building scientific databases is extremely difficult and expensive. Costs could be reduced if the experts who curate the deposited data, are provided with data that are reviewed by other experts at lower levels for accuracy and consistency. Since expertise is distributed around the world, a common platform that implements a well-accepted work process is needed to support such community curation. The workflow is complicated because there are many different types of biochemical data and the relationships among the data are complex; different data types need different kinds of checks; procedures to deposit, review, revise, and accept data; and the volume of data is very large. We have automated the workflow used in curating several types of biochemical data. This model is flexible enough to accommodate additional processes idiosyncratic to particular groups of curators, such as those for enzymatic reactions, biochemical terms, and molecular structures. This work demonstrates the application of workflow technology to intellectually complex, geographically distributed, multidisciplinary scientific processe

Porphyrin-based molecular triad systems for use in spin-entanglement and catalysis experiments

Here we study a set of porphyrin-based molecular triad systems for the purpose of using the long-lived charge separated state (CCS), 1) as a tool to hyperpolarise, entangle and measure nuclear spins in molecules and 2) to spin-catalyse molecular hydrogen encapsulated in a fullerene cage as part of a porphyrin-C_60 system. In light of the above goals, we firstly study a series of triad systems where the moieties of each system are chosen so as to increase the driving force for electron transfer and obtain a system where the CSS is long-lived (on the order of a few tens of milliseconds). We study the porphyrin-based systems using a combination of theoretical, electrochemical and electron paramagnetic resonance (EPR) studies, to quantitatively understand the charge and spin dynamics. We find that from a series of three triad systems (TAPD-MP_Ar-C_60 where M = Zn, H_2 and Cd) the longest-lived CSS2 is obtained on the zinc porphyrin triad, 32 ms at 10 K — due to slow T_1 relaxation. The singlet recombination lifetime is 11 µs in xylenes and 3 µs in 2MeTHF, at cryogenic temperatures. The highest quantum yield is obtained from the cadmium porphyrin triad, around 0.15. Magneto-photo-selection experiments along with EPR simulations are used to derive mechanistic detail about energy migration in the triad systems after photo-excitation, while Liouville space simulations are used to extract spin Hamiltonian parameters for the SCRP. We detect ortho-H_2 using ENDOR and NMR before attempting to use the CSS as a spin-catalyst for H_2. In the final chapter we use optical pump-probe spectroscopy to monitor the charge migration at room temperature where we find the lifetime of the CSS_2 to be around 8 – 10 ns. We also present a new electric field resonator design for carrying out microwave dielectric absorption experiments