This thesis presents a systematic scheme to determine the optimal propulsive/axial force ratio of a single-sided permanent magnet axial-flux motor (SPMAM) along with its operational constraints on both the winding currents and the speed induced voltages. According to the rotating magnetic field theory with combining the recoil line characteristics of permanent magnet and the equivalent operational magnetic circuits, appropriate projection of the stator currents to achieve an optimal ratio of the machine propulsive/axial forces has been confirmed through detailed three-dimensional finite element analysis (3-D FEA) and numerical studies. From these evaluations, a feasible operational guidance for SPMAM field oriented control (FOC) scheme realizations can be suitably provided. Finally, based on the proposed optimal scheme, a DSP-based drive system has been successfully implemented, and the desired operational strategy realization can be achieved.

This thesis is to investigate in detail the frameworks of speed and lift control schemes of transverse flux linear switched-reluctance machine (TFLSRM), and to verify the validity of the resulting controllers by Matlab/Simulink simulation. Before the developments of adequate control parameters, the system inductance matrix and relative state equation regarding machine voltage and force operations were devised. By using the system linearized small signal model, and Routh stability criterion, the range for all parameters of controllers can be derived. Finally, to control the propulsive and lift forces simultaneously, a supplemental phase voltage adjustment scheme has also been provided to better the overall system performance.

The objective of this thesis is to integrate available commercial Software/Hardware package and to establish appropriate graphic user interface (GUI) for transverse flux linear switched-reluctance machine (TFLSRM) motion control. By changing the machine feedback signals, package will be matched with TFLSRM. The control unit of the whole system is based on digital signal processor (DSP) with its software interface being built up by Matlab/Simulink. Hence, users can operate this machine directly by observing the output result from computer monitor. By combining with suitable PI controller, friction variation can be eliminated and the control objectives of the TFLSRM under a desirable velocity also can be achieved.

The coastal wetlands at Aransas National Wildlife Refuge near Austwell, Texas, support the last migrating population of whooping cranes during the winter months (October through April). With a population currently at 216 individuals, these are the rarest cranes in the world. The wetlands in which they winter are a part of the San Antonio Bay system, a bay that receives constant fresh water flow from the Guadalupe River. Currently there is a plan for using water diverted from the Guadalupe River just before it enters San Antonio Bay as a water supply for the greater San Antonio metropolitan area located 200 km to the northwest. The Guadalupe River delivers nutrients and sediment into the estuary along with fresh water. Because of the importance of sediment within a tidal wetland ecosystem, it is imperative to understand the sediment budget and underlying forces that drive it if one is to ultimately grasp how this ecosystem functions. To document natural and anthropogenic factors exerting control over sediment movement in this system, three sites on tidal creeks near the boundary between marsh and bay were chosen. The Gulf Intracoastal Waterwayparallels the marsh edge. Over six, non-consecutive weeks water level and velocity were automatically monitored in the tidal creeks. Automated water samplers extracted water samples that were analyzed for suspended sediment. In addition, bedload traps were deployed in one creek to monitor sediment movement along the channel bottom. Inflow exceeded outflow during the study. As a result there was a net influx of suspended sediments into the marsh. Bedload material also moves with current direction, and it appears to move in response to barge induced outflow currents. Barges passing on the Gulf Intracoastal Waterway exert influence on water level, flow direction, and velocity within tidal creeks. Natural factors such as winds, tides, and freshwater input from upland runoff or river discharge also impact suspended and bedload sediments.

The objective of this thesis is to provide the modeling procedure for a tubular permanent magnet generator with Halbach array. The cylindrical-coordinated magnetic flux distributions generated by the stator winding currents and permanent magnets can be realized by deriving the magnetic vector potential in Bessel form from the Maxwell's equations. Then, the functional expressions of inductance matrix and magnetic flux linkage can be obtained. The detailed mathematic model of the proposed system combined with the actual operational properties can be further established and implemented by using the Matlab/Simulink software. The applicability of such mathematic model is also confirmed with experimental results.

Thesis (Ph. D.)--West Virginia University, 2001. / Title from document title page. Document formatted into pages; contains xviii, 130 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references (p. 98-104).

Title from PDF of title page (University of Missouri--Columbia, viewed on Feb. 19, 2010). 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. Dr. Randy Curry, Thesis Supervisor Includes bibliographical references.

Thesis (M.S. in Engineering Science)--Naval Postgraduate School, December 2003. / Thesis advisor(s): Ashok Gopinath. Includes bibliographical references (p. 83-84). Also available online.

A protocol was developed to measure ammonia emission concentrations from dairies using an isolation flux chamber. A hybrid dairy in Comanche county, Texas, was measured for one week each during August 2002 and January 2003. Sixty total ammonia samples were taken from the free stall barn, open lot, mixing tank, separated solids, compost, and two lagoons using the developed protocol. The ammonia concentration measurements were made using a chemiluminescence analyzer located inside a mobile laboratory. From the emission concentrations recorded, it was estimated that 9.68 metric tons of ammonia were produced from this dairy per year. An emission factor of 13.34 ± 28.80 kilograms per day per thousand head of cattle (kg/day/1000 head) was estimated for this dairy (±95% confidence intervals) during summer conditions. For winter conditions the emission factor was 12.05 ± 12.89 kg/day/1000 head. The 11% difference of the emission factors from summer to winter conditions was predominantly from the change in ambient and control volume temperatures (a mean difference of approximately 25 degrees Celsius), differences in source temperatures, and seasonal variability in husbandry. The adsorption of ammonia onto different polymer tubing used in pollutant stream conveyance was researched for possible systematic losses. Teflon and low density polyethylene (LDPE) were tested for ammonia losses with treatments of: temperature, length, and inlet concentration. Inlet concentration and temperature were significant factors used to describe ammonia adsorption for Teflon, whereas LDPE was also affected by tubing length. These factors were used to create a model to correct the summer dairy measurements for ammonia losses, resulting in an emission factor increase of 8.3% over the original value obtained from the flux chamber. A nitrogen mass balance was performed to estimate the amount of nitrogen available for ammonia formation as excreted - 177.5 kilograms per year per animal (wet basis). The amount of ammonia excreted per year was also estimated to be 26.63 kilograms per year. The measured ammonia emitted from the dairy was five times less than the ammonia excreted and thirty-six times less than the total nitrogen excreted.

Degradation of permafrost in peatlands can convert forested peat plateaus to inundated collapse bogs. Due to increased unfrozen soil carbon stocks and more saturated conditions, collapse bogs can potentially be large emitters of methane. Using a network of bubble traps permanently installed in peat, I tested several hypotheses about controls on ebullition in collapse bogs with varying time since thaw in interior Alaska. Ebullition increased during the growing season, likely due to increased substrate availability and warmer soils. Bubbles were found primarily in shallow peat layers, and were dominated by modern carbon. Ebullition hot spots were associated with high sedge density throughout the collapse sites. Episodic ebullition occurred during atmospheric pressure changes. Overall, my study demonstrated that permafrost thaw in peatlands will result in methane emissions through ebullition that include both young and old carbon, contradictory to the generally accepted paradigm; that ebullition in peatlands is solely a surface process.