A high quality, historical surface air temperature data set is essential for the reliable investigation of climate change and variability. In this study, such a data set has been prepared for Australia by adjusting raw mean annual temperature data for inhomogeneities associated with station relocations, changes in exposure, and other problems. Temperature records from long-term stations were collaborated from the set of all raw data held by the Australian Bureau of Meteorology. These long-term records were extended by combining stations and manually entering previously unused archived temperature measurements. An objective procedure was developed to determine the necessary adjustments, in conjunction with complementary statistical methods and station history documentation. The objective procedure involved creating a reference time series for each long-term station, from the median values at surrounding, well-correlated stations. Time series of annual mean maximum and mean minimum temperatures have been produced for 224 stations, and the adjusted dataset has been made available to the research community. The adjusted data are likely to be more representative of real climatic variations than raw data due to the removal of discontinuities. The adjusted data set has been compared with previously used temperature data sets, and data sets of other parameters. The adjusted data set provides adequate spatial coverage of Australia back to 1910. Additional adjusted data are available prior to this date at many stations. Trends in annual mean maximum, minimum, the mean of the maximum and minimum, and the range between the maximum and minimum, have been calculated at each site. Maximum and minimum temperatures have increased since about 1950, with minimum temperatures increasing faster than maximum temperatures.

Graduation date: 1977

Measurements of the fluctuations of humidity, temperature and velocity were made in the marine boundary layer. The humidity fluctuations were measured with a Lyman-alpha humidiometer. Temperature fluctuations were measured with a dry thermocouple and a platinum resistance thermometer. Velocity fluctuations were measured with a three component sonic anemometer. These measurements were made from the Floating Instrument Platform (FLIP) operated by the Scripps Institution of Oceanography near San Diego in February, 1969 and during the Barbados Oceanographic and Meteorological Expedition (BOMEX) in May 1969. The data were processed by digital techniques and the various spectra, cospectra and quadspectra between the velocities, humidity and temperature were obtained. Integrals of the cospectra were produced which allowed estimates of the fluxes of latent and sensible heat to be made. The normalized spectra of humidity fluctuations in San Diego and BOMEX have similar shapes. The normalized cospectra between vertical velocity and humidity in San Diego and BOMEX have similar shapes. Universal forms for the normalized humidity spectrum and the normalized cospectrum between vertical velocity and humidity may exist. The normalized spectra of the temperature fluctuations in San Diego and BOMEX have different shapes. The differences in shapes may be related to stronger radiation effects during BOMEX than in San Diego. The normalized cospectra between vertical velocity and temperature in San Diego and BOMEX also have different shapes. It is probable that a universal form does not exist for the normalized temperature spectrum or for the normalized cospectrum between vertical velocity and temperature. Directly measured values of the latent and sensible heat fluxes were used to test the validity of the bulk aerodynamic method of predicting the latent and sensible heat fluxes from the mean wind speed and mean air-sea humidity or temperature differences. The limited results from San Diego indicate that the sensible heat flux may probably be predicted from the mean wind speed and the mean air-sea temperature difference in temperate regions. The bulk aerodynamic method was not useful for predicting the sensible heat flux in BOMEX. The observed values for the sensible heat flux were much larger than would be predicted. The latent heat flux could be predicted from the mean wind speed and the mean air-sea absolute humidity difference with a probable error of less than 20%. The validity of the formula developed by Bowen (1926) for predicting the Bowen ratio (sensible heat flux/latent heat flux) was tested with directly measured values of the Bowen ratio. It was found that in San Diego the Bowen ratio could be predicted with a probable error of 15%. The Bowen ratio predicted for BOMEX was too low by a factor of two or more. The ability to predict the Bowen ratio from the ratio of the temperature fluctuations to the humidity fluctuations in the 0.05-0.1 Hz range was investigated. The method predicted the Bowen ratio with a probable error of 15% in San Diego and 20% in BOMEX. / Graduation date: 1971

The miniaturization of Microtechnology-based Energy, Chemical and Biological Systems (MECS) is made possible by the use of high aspect ratio microchannel arrays to increase the surface-area-to-volume ratio of the flow conduits within the devices, resulting in an improvement in the heat and mass transfer performance of the devices. However, advantages of the MECS concept cannot be applied to high-temperature applications (above 650��C) due to lack of high-temperature MECS devices; therefore, the development of high-temperature MECS devices is necessary to overcome this bottleneck. This dissertation involves the development of high-temperature MECS devices from a high-temperature material, nickel aluminide (NiAl). NiAl foil was synthesized from elemental nickel (Ni) and aluminum (Al) foils through a two step process--tack bonding and reactive diffusion. The elemental foils were tack bonded at 500��C, 3.9 MPa for 15 minutes. The reactive diffusion process was then performed through a heat treatment at 1000��C for a period of time corresponding to the thickness of the composite foil. The synthesized NiAl foil showed an atomic ratio of Al to Ni up to 0.96. The foil also showed a decent flatness and surface roughness. This dissertation proposes a reactive diffusion bonding as a joining technique of nickel aluminides. An investigation of bonding parameter effects on the warpage of nickel aluminide fins in the reactive diffusion bonding process was performed. Results showed that bonding time and temperature had significant effects on warpage of the fin. The fin warpage increased with the increase of bonding time and bonding temperature. Results also suggested that the bonding pressure had an effect on the fin warpage. However, chemical compositions of the fin were not significant to the warpage. This research also proposes a new fabrication procedure for producing NiAl MECS devices. NiAl foils were used as the starting material, and the reactive diffusion bonding technique was employed as the joining technique. The research outcome indicated the viability of the proposed method in fabricating NiAl MECS devices. This method achieved leak-tight devices with a reasonable fin flatness. / Graduation date: 2003

Graduation date: 1997

Graduation date: 1996

Effects of thermal and electron beam (e-beam) processing on microbial inactivation and physichochemical properties of surimi and surimi seafood were investigated. Thermal-death-time (TDT) concept was used to model Staphylococcus aureus inactivation by heat and e-beam. Gurney-Lurie charts were used to estimate temperature during thermal processing of surimi seafood. Dose mapping technique was used to estimate dose absorbed by surmi seafood during e-beam processing. The dose absorbed increased up to 2 cm and then it gradually decreased, reaching a minimum at 5 cm depth of surimi seafood. It was determined that one and two-sided e-beam can efficiently penetrate 3.3 and 8.2 cm of surimi seafood, respectively. The D-value for thermally inactivated S. aureus was 0.65, 1.53, 6.52, 49.83, and 971.54 s, at 95, 85, 75, 65, and 55°C, respectively. The D-value for S. aureus inactivated with e-beam was 0.34 kGy. The z-value for thermally inactivated S. aureus between 55-95°C was not linear. Thermal processing degraded texture and color of surimi seafood. E-beam enhanced firmness and decreased the b* value of surimi seafood. Myosin heavy chain (MHC) degraded proportionally to the e-beam dose. Actin was not affected by e-beam except treatment at 25 kGy. Hydrophobic interactions and disulfide bonds were formed in raw Alaska pollock surimi when treated with e-beam. / Graduation date: 2002

A magnetic force microscope (MFM) is a special type of scanning force microscope which measures the stray field above a ferromagnetic sample with the help of a ferromagnetic cantilever. The aim of this project was to design and build a MFM head and interface it with a commercial scanning probe electronics controller with the help of an appropriate force sensor. The MFM head and the force sensor were to be designed to work at low temperatures (down to 4 K) and in high vacuum. During this work, a magnetic force microscope (MFM) head was designed. Its design is symmetrical and modular. Two dimensional views were prepared to ensure proper geometry and alignment for the various modules. Based on these views, individual parts in the various modules were manufactured and combined for the final assembly of the head. This MFM head has many essential and advanced features which were incorporated during the design process. Our MFM head has an outside diameter of 5 cm and thus has a low thermal mass. The head operates inside a 100 cm long vacuum can which is kept in a cold bath inside a superinsulated dewar. Other features of this MFM head include thermal compensation of the important parts, flexibility to use commercial MFM cantilevers and a large scan range compared to the previous designs. Some of the anticipated system specifications are: 1) room temperature scanning range of 175?? 175 ??m, 2) low temperature scanning range between 35-50 ??m, 3) smallest detectable magnetic force in the range of one pN and 4) smallest detectable magnetic force gradient in the range of 10-3 to 10 -5 N/m. This MFM head was interfaced to a commercial scanning probe electronics apparatus by designing a fiber-optic interferometer as the sensor for the detection of the cantilever deflection. The fiber-optic sensor also has features of its own such as stability, compactness and low susceptibility to noise because of all-fiber construction. With this MFM head, we hope to image many magnetic samples which were previously impossible to image at Texas A&M.

Graduation date: 1991

Color is a visual characteristic which imparts the ability to categorize different objects. When light strikes an object, there are three possibilities as to what can happen. The light may be reflected, refracted or scattered. Human perception of color is due to a combination of these. Plastics are polymeric materials. Polymers are generally colorless and need colorants in order to have some color. One or more pigments in certain ratios can be used to give a specific color to plastics. Slight variations in the proportions of either of the used pigments, or their dispersion, may result in a color that is different from the desired one. There can also be many other reasons for color mismatch such as processing or degradation effects. This study utilized the historical data records of SABIC IP to look at effects of changing Grade on color (i.e. when the same color is produced from resin blends which may have different amounts of resins, pigments or additives). These records were also used to study effects of change in screw diameter and configuration on color (i.e. when the same grade of a color is produced on two different production lines, different screw diameters and configurations). The effects of the processing parameters on the colors were also investigated by carrying out experiments using a twin screw extruder at SABIC IP’s plant in Cobourg. Resins, pigments and additives were dry blended and extruded while being subjected to different processing conditions. Three processing parameters, namely temperature, rpm and feed-rate, were chosen for the study. A three level factorial design of experiments was used. An analysis of variance (ANOVA) has been utilized to find the effects of individual parameters on color and the interaction between two parameters and their cumulative effect on color. / UOIT