Thesis (M.S.)--University of Missouri-Columbia, 2006. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file viewed on (February 26, 2007) Includes bibliographical references.

This study examines the different characteristics of adopting private debt, corporate bonds, and bank debt in the Taiwanese listed companies that obtained new debt financing from 2002 to 2004. The Logistic Regression Model is performed to find out the main determinants to affect the choice of debt instruments, and Two-Stage Least Squares is used to examine the effects of different debt instrument on equity risk. The results are as followed: 1. The higher the flotation cost the higher the possibility of the firm to choose issuing public bonds. On the other hand, the lower the flotation cost the higher the possibility of the firm to choose issuing private debt. 2. Firms with the highest information asymmetry tend to borrow from banks, and those with the lowest information asymmetry are likely to issue public bonds. 3. Firms with the highest credit quality exhibit a strong preference for public bonds, firms with middle credit quality prefer to borrow from banks, and the lowest credit quality prefer to borrow from private debt sources. 4. Firms with the lowest managerial ownership tend to borrow from private debt. 5. As to the equity risk from the debt sources, it increases with the size of the corporate bonds or private debt, and decreases with the size of the bank debt.

Graduation date: 1994

Graduation date: 1992

Among the many safety hazards facing chainsaw operators, the phenomenon known as kickback is the most dangerous. Kickback occurs when the chain at the tip of the chainsaw is caused to stop abruptly, and transfers the energy of the cutting chain to motion of the saw. The saw will rotate backward toward the operator rapidly. The limited amount of published research on the topic of chainsaw kickback was conducted to develop standardized testing for consumer chainsaws. Modern chainsaws are equipped with safety measures such as low-kickback cutting chains and hand-guard braking mechanisms. These mechanisms have greatly improved the safety of chainsaws, but their inherent mechanical simplicity leaves room for improvement. The current work presents the research that analyzed the possible methods for detecting kickback electronically. Phase 1 of this work utilized a set of two accelerometers and a single gyroscope to determine if it is possible to distinguish a kickback event from normal cutting operations. A method for applying weighting coefficients to the three sensor readings, then summing the three signal values was optimized to obtain the greatest margin between kickback and normal cutting. The result of this study was that kickback is most easily identified by using only a gyroscope and setting a threshold. Phase 2 focused on detecting kickback as early as possible. Three methods were attempted: Signal Differentiation, a Simplified Bag of Words method, and applying a Support Vector Machine with selective undersampling and a stack of classifier vectors. Signal differentiation, while detecting the kickback events earlier, also suffered from many false positives. The Bag of Words method was unsuccessful in creating results different than the threshold method from Phase 1. The Support Vector Machine classification was able to detect kickback an average of 19.4 ms before the simple threshold method with no occurrence of either false positives or false negatives. This method is the most reliable and provides the greatest likelihood of detecting kickback early. / Graduation Date: 2013

This study addresses the development of a sensor to monitor chemical adsorption and charge transfer processes on a surface using a contact potential difference probe (CPD). The current investigation is an outgrowth of ongoing research on non-vibrating CPD probes (nvCPD) which led to the recent development of a novel measurement technique utilizing optical stimulation: optically stimulated CPD (osCPD). Primary outcomes of this thesis are the theoretical modeling, fabrication and demonstration of a functional osCPD sensor. The research also involved significant engineering and experimentation in the design, development, and application of this sensor to oil condition monitoring. This technique measures dielectric and chemical properties of a fluid at the interface between the fluid and a semiconductor substrate. Chopped visible light is used to stimulate the rear surface of a semiconductor substrate, and a CPD probe measures the work function response of the semiconductor on the front surface of the substrate. The work function response is influenced by the nature and quantity of adsorbed species on the top surface, allowing the probe to detect changes in chemical composition at the substrate/fluid interface. An analytical model is developed that relates the osCPD sensor output signal to the chemical and dielectric properties of the oil sample, as well as to the geometry, composition, and control inputs of the silicon substrate and test fixture. In this investigation, the osCPD sensor was used to evaluate dielectric and chemical properties of commercially available engine oil. Oil samples were intentionally degraded through thermal aging (oxidation) and through addition of known contaminants. The osCPD sensor shows good sensitivity to depletion of antioxidants in the oil, as well as to the presence of ferric chloride, an oil-soluble salt typically used to calibrate laboratory test equipment.

A compact low-frequency projector is of crucial importance especially in underwater acoustics due to the frequency dependence of the absorption. To improve the efficiency of an omnidirectional acoustic source at low frequencies, parametric amplification may be used by adding a thin layer of nonlinear medium around a spherical transducer. The parametric effect is based on the interaction of two acoustic waves propagating through a nonlinear medium to produce a difference frequency wave. If both primary frequencies are sufficiently close enough, the result is the creation of a low frequency wave. Investigation is required to find the optimal medium, that is to say, one with a large nonlinear coefficient and a low sound speed. Such a source has already been built using a medium composed of a gel and microsphere mixture. In this case, the nonlinear coefficient is highly pressure dependent reaching a maximum when the microspheres buckle. The need is to optimize the material layer to increase the range of hydrostatic pressures over which the projector is useful.

This thesis addresses the use of a vibrating Kelvin probe to monitor the change in the front surface potential of a silicon wafer while the rear surface is illuminated with monochromatic, visible light. Two tests were run to verify the change in surface potential. One test increased the intensity of the light and the other increased the wavelength while recording the front surface potential. The change in the surface potential for a range of intensities of incident light was recorded and analyzed. The results show that the change in surface potential increased with increasing intensity. For each wafer, the smallest change in surface potential occurred at the lowest intensity, 3.77 mW. In the same respect, the largest change in surface potential occurred at the highest intensity, 17.8 mW. For all wafers, the change in surface potential ranged from approximately 8 mV at 3.77 mW to approximately 80 mV at 17.8 mW. The change in the surface potential for a range of wavelengths of incident light was also recorded and analyzed. The results showed that the change in surface potential formed a skewed bell curve with increasing wavelength of incident light. For each wafer, the largest change in surface potential occurred at mid-range wavelengths, between 600 nm and 700 nm. The smallest change in surface potential occurred at 450 nm, the shortest wavelength, and 800 nm, the longest wavelength. For all wafers, the change in surface potential ranged from approximately 8 mV at 800 nm to approximately 165 mV at 700 nm. A model based on excess electron diffusion within the silicon wafer was used to predict material properties. After curve fitting the model with experimental results, an excess electron lifetime of ôN = 17 µs and surface recombination rates of sFRONT = sREAR = 18,000cm/s were predicted. These values suggest poor silicon wafer quality relative to commercial silicon devices. Regardless of the quality, the results show that the front surface potential of a silicon wafer is affected by incident light on the rear surface. The quantitative effect of the light is dependent on the properties of the light and the material properties of the silicon wafer.

On 30 December 1986, a local fisherman incidentally discovered the remains of a seventeenth-century merchantman off the coast of Rincon, a small municipality on Puerto Rico's west coast. Some days later, he and some acquaintances extracted objects from the site and stored them in a nearby restaurant. The assemblage of artifacts recovered included, among other items, pins, scissors, ordnance, pewter ware, woodworking tools, a myriad of concretions and a nautical astrolabe. It is from the last that the wreck site took its name. The operation continued for months until local authorities, alerted by a member of the salvage group, issued a cease and desist order. At that point, the whole affair entered a legal process that on the summer of 2005 had not reached its conclusion. The purpose of this thesis is twofold. First, the author presents the story of the shipwreck from the moment it was found until the court ruled regarding ownership of the artifacts. Since this was the first time ownership of a shipwreck was debated in Puerto Rican courts in recent history, this gives the reader an idea of how legal precedence was established concerning the island's submerged cultural resources. Second, based on what was popularly perceived to be the site's most remarkable find, a study was developed on the sea or mariner's astrolabe, a navigation instrument that played a fundamental role in the process of European maritime expansion during the late fifteenth, sixteenth and seventeenth centuries. The reader of this text will learn that, during the fifteenth century, Portuguese navigators saw the need to gradually depart from the traditional Mediterranean navigation technique known as "dead reckoning." As their explorations along the West African coast forced them to sail far into the Atlantic Ocean for prolonged periods, a new method was developed that consisted of measuring the angle of certain heavenly bodies above the horizon in order to determine the latitude of the observer with reasonable precision. For this purpose, instruments that traditionally belonged to the field of astronomy were adapted to be used by seamen. Among them was the astrolabe, which became the most popular by the turn of the sixteenth century. After discussing the instrument's origin and development, the author analyzes how a renewed interest on the nautical astrolabe, which emerged in Portugal in the early twentieth century, introduced the instrument to the field of modern scholarly research. This work also presents a catalogue of sixteen sea astrolabes, some of which have never been published. The catalogue shows statistics and other relevant information, while placing the artifacts in the context of the previously existing data.

Thesis--Philosophy--London--King's College, 1999. / Bibliogr. f. 365-402.