The effects of realistic surface properties on low temperature space observatories

I investigate the effects of modelling radiative heat transfer correctly on equilibrium temperatures of passively cooled telescopes. I compare the traditional diffuse approximation with a surface exhibiting the directional properties of gold, both with an emissivity of 0.03. I also modeled surfaces with much lower, more realistic emissivities. Directional surface properties are derived from values of optical constants at room temperature since there exists a dearth of reliable data at cryogenic temperatures. The effect of using optical constants at different wavelengths is also investigated. My simulations show the diffuse assumption produces higher temperatures than the directional surface. Both surfaces produce higher temperatures than the low emissivity cases when conductivity is low, whilst the reverse is true for high conductivity. The directional surface always outperformed the diffuse surface For radiative exchange, the diffuse approximation simply produces pessimistic results. However, incorrect modelling of radiative exchange can have knock-on effects. The higher emissivity, diffuse approximation predicts much greater improvements due to tilted sunshields than would realistically occur. This may recommend unnecessary changes to telescope designs in the attempt to improve cooling performance. The lack of reliable directional radiative data for candidate passive cooling materials will require a major measurement program before a mission is launched. In this thesis I describe apparatus to help in such measurements. The bi-directional reflectometer quickly and accurately builds up a picture of directional surface properties, performing very well when combined with a reliable laser and measuring device, the few component parts being relatively cheap. Thus, the many directional measurements required for accurate modelling could be made cheaply and quickly. The multiple reflection cell was designed to make high accuracy measurements at one angle only. This was not as effective as hoped due to laser problems, but should be able to make very good measurements. Further work is recommended

Changes in carbohydrates of Navy beans during hydration and subsequent thermal processing

Navy beans were subjected to six different hydration protocols that varied in time, temperature, and methodology after which they were thermally processed in both a brine solution and a typical baked bean sauce. Beans, isolated starch, and hydration fluid were analyzed immediately after the completion of hydration protocols. Significant differences were noted between those protocols utilizing low heat (1 and 2) and those utilizing high heat methods (3-6). Bean from low heat protocols were firmer overall. Starch granules from low heat beans were smaller in overall size, experienced less surface damage retained birefringence, and could absorb more water (higher swell factor). Analysis of the hydration fluid showed no noticeable differences. Analysis of the canned products showed that intense thermal processing effectively caused gelatinization in all protocols as confirmed by DSC and light microscopy. Isolated starch had little to no abilities to retain water. Granules from all protocols in both mediums showed extensive damage, cracking, and possible leaching which is believed to be the cause of substantially lower amylose findings in starch isolated from canned as compared to hydrated beans. Analysis of brine solution revealed increased leaching of carbohydrates, amylose, and proteins. The Kramer compression shear cell detected significant texture differences in beans canned in brine that were hydrated by novel protocols 5 and 6 but not in novel protocol 4, the current protocol (3), and the traditional protocols (1 and 2). Likewise, a probe texture analyzer, determined beans hydrated by protocols 5 and 6 to have firmer skin and flesh overall as compared to the other protocols. The Kramer sheer press was not able to detect differences in beans canned in sauce while the probe texture analyzer was able to detect differences in beans from traditional protocol 1 compared to protocols 3-6. Overall, it was discovered that novel hydration protocols 5 and 6 produce firmer beans when canned in brine solution compared to the current (3) and traditional protocol (1). Beans hydrated by current (3) and novel protocols (4 – 6) show no significant differences in texture when canned in typical baked bean sauce

A Bayesian Approach to Aerial Localization of Radioactive Sources

Securing nuclear material has become an important area for the safety of the U.S. and other countries. Within nuclear security, there is a potential to use orphaned or stolen radioactive sources to cause harm. As the amount of radioisotopes used by government and commercial businesses increases, the need to secure these sources becomes exponentially more difficult. It is well known that there have been several cases of lost, orphaned or stolen nuclear sources across the globe. There is a need for state-of-the-art radiation search methods to search for these potentially dangerous radioactive sources that could be misplaced. While there are several well established methods for ground-based source search, the options for using air-based detection systems are not as effective. This thesis describes the development and implementation of the Broad-Area Search Bayesian Processor (BASBP) algorithm. This program was created to effectively search for lost sources from an unmanned aerial detection system. This approach utilizes Bayes\u27 theory coupled to a MCNP weighting method to quickly estimate the location of possible radioactive sources. This Bayesian algorithm shows improvements in source localization for low-level source isotopes. BASBP has been shown to locate radioactive sources that are weaker than standard minimum detectable activities. It also shows promise for using other data to more effectively locate lost radioactive sources

The Structural Geology of the Tectonized Ultramafic Suite of the Table Mountain Massif, Bay of Islands Complex, Newfoundland

Table Mountain is the northernmost massif in the Bay of Islands Ophiolite. It represents a continuous, approximately 7 kilometer thick, section of residual harzburgite tectonites capped by a nearly flat-lying assemblage of deformed and undeformed cumulate rocks. The notable mesoscopic structural features of the massif include a zone of penetrative deformation extending upsection from the tectonized harzburgites approximately 500 meters into the dunites and basal cumulates. The orientation of the foliation and associated lineations as well as the inferred shear sense within the zone is consistent with that affecting the harzburgites. Highly deformed dunite lenses which range in thickness up to 300 meters and up to 5 kilometers in lateral extent lie beneath the plagioclase-bearing cumulates. They have a gradational contact with the harzburgites. Throughout the harzburgite section compositional layering, defined by variations in enstatite concentration, is parallel or nearly parallel to the S1 foliation., The layering may either have limited lateral extent (associated with transposed intrusives) or it occurs in clusters of layers traceable as a group for several kilometers. The inclination of both the foliation and the layering relative to the essentially flat-lying contact between the cumulate and residual suites becomes progressively more shallow at deeper levels within the harzburgite. Petrographic examination of the massif indicates the presence of clinopyroxene and altered plagioclase (now hydrogarnet and sericite) in the upper 50 to 200 meters of harzburgite adjacent to the dunite lenses. Trace amounts of subhedral clinopyroxene occur throughout the harzburgite, typically associated with polycrystalline enstatite clots. Petrofabric analyses of olivine fabrics of samples from the harzburgite section indicate that the [100] maxima strengthen with increasing depth from the cumulate carapace. Fabric asymmetries relative to the trace of the foliation and spinel lineation indicate a dominantly sinistral shear sense. This concurs with the consistently oriented fold vergence data. A model of a spreading ridge system, modified after Dewey and Kidd (1977) and Casey (1980), is adapted to explain the herringbone relationship between the compositional layering of the undeformed cumulates and that of the S1 foliation. This foliation is here proposed to dip away from the parental ridge axis