Theses and Dissertations

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  • Publication
    Spread-Spectrum Ultrasonic Evaluation System design
    ( 1993) Kayani, Jahangir Khan ; Russell, Steve F.
    This work aims at investigating various options for the embodiment of a spreadspectrum ultrasonic NDE system that can be used in a wide variety of applications. The idea is to study the trade-offs and compare the performance of various design options. A brief theory of a working system model is first developed. Various options for the implementation of individual system functional blocks and the associated theory are then discussed. Possible overall system design options are presented. Lastly, detailed designs for some of the most promising options are given.
  • Publication
    A multicultural community renewal college for the Regents Canal area of Hackney Borough, London: Subsidiarity and significants as planning and architecture strategies
    ( 1993) Karlson, Paul John ; Findlay, Bob ; Kihl, Mary
    Because architects and planners create places with boundaries which contain, and sometimes cause, social problems, we bear a high degree of responsibility for the products of our design activity. Through an understanding of diversity and need levels of residents, it is possible to improve the physical environment of the residents in a defined community. This paper pursues this construct as it relates to the Regents Canal area of Hackney Borough, a distinct low income multicultural area in Greater London, England. The paper goes on to suggest a multicultural community college as an instrument for improving the social and environmental situation of the Regents Canal area.
  • Publication
    The dialogs of the spirits
    ( 1993) Kangai, Phebion
    The idea behind this thesis can be traced conceptually to my early experiences with colorful reproductions of Western art at an Anglican mission high school in Zimbabwe. At that time I never suspected there could be a link between the Shona spirits and Western art, or any other art for that matter. But I do remember being intensely fascinated by pictures such as Paul Klee's "Death and Fire" (1940). I was attracted to Paul Klee and similar Western artists because of something powerful and familiar but intangible in their images. Later on I connected what I saw in these images to the spirit dances in Shona culture. This connection was even more powerful when I came across the work of the Abstract Expressionists later. Thus, this thesis revolves around the ideas of Shona dance rituals and spirit posession, current theoretical developments in contemporary Africa art, and the legacy of Western colonialism in African art.
  • Publication
    Laboratory and field study of starch-polyethylene degradable plastic bags
    ( 1993) Johnson, Kenneth Earl ; Pometto, Anthony L.
    Six types of starch-polyethylene degradable plastics were evaluated for the release of water-soluble toxic compounds under accelerated degradation conditions. A plastic strip (2.5 X 15.2 cm) was placed in a 250-ml Erlenmeyer flask with 100 ml of ASTM type I water with or without trace-element solutions and shaken at 65°C and 110 rpm for 20 weeks in replicates of two. High temperature was used to accelerate the oxidative degradation of polyethylene. Plastic degradation was measured by loss of tensile strength, percent elongation, strain-energy, and weight-average molecular-weight. The most rapid period of polyethylene thermal degradation was complete for most materials by day 28. Ten-milliliter aqueous samples were removed from each flask at days 1, 7, 28, 56, 84 and 140 {water volumes were maintained at 100 ml with fresh type I water), filtered through glass filters, then evaluated by using the Microtox Toxicity Analyzer (Microbics Corporation, Carlsbad, CA). No water-soluble toxic compounds were detected during the period of rapid film degradation. Toxicity was observed at day 28 for one film and for all films at day 84, which could result from the release of small oxidative compounds such as formaldehyde and acetaldehyde. Because of the sensitivity of this assay, positive results must be confirmed by other in vitro studies. The degradation performance of 11 types of commercially, produced starch-polyethylene degradable plastic compost bags was evaluated in municipal yard waste compost sites at Iowa State University (Ames), Carroll, Dubuque, and Grinnell, IA. Masterbatches for plastic production were provided by Archer Daniels Midland Co. (Decatur, IL) (ADM), St. Lawrence Starch Co. Ltd. (Mississauga, Ontario) (SLS), and Fully Compounded Plastics (Decatur, IL) (FCP). Bags differed in starch content (5-9%) and pro-oxidant additives (transition metals and a type of unsaturated vegetable oil). Chemical and photo-degradation properties of each material were evaluated. SLS and FCP materials photo degraded faster than did ADM materials, whereas all materials containing transition metals demonstrated rapid thermal oxidative degradation in 70°C oven (dry) and high-temperature high-humidity (steam chamber) treatments. Each compost site was seeded with test strips (200 to 800 each type) taped together, which were recovered periodically over an 8- to 12-month period. At each sampling date, compost row temperature was measured (65- 950C); location of the recovered test strip was recorded (interior or exterior); and at least four strips were recovered for evaluation. Degradation was followed by measuring change in polyethylene molecular-weight distribution via high-temperature gel-permeation chromatography. Our initial 8-month study indicated that materials recovered from the interior of the compost row demonstrated very little degradation whereas materials recovered from the exterior degraded well. In the second year study, however, degradation was observed in several plastic materials recovered from the interior of the compost row by month 5 at Carroll and almost every material by month 12 at Grinnell. The plastic bags collected from each community followed a similar degradation pattern. To our knowledge, this is the first scientific study demonstrating significant polyethylene degradation by these materials in a compost environment.
  • Publication
    Supervisory behaviors of cooperating teachers: A comparison of actual and preferred behaviors
    ( 1993) Jensen, Sharon Jane ; Strong, Mary
    The purpose of the study was to collect data from cooperating and student teachers from two midwestern universities during the last two weeks of the traditional student teaching experience. By comparing the actual and preferred supervisory behaviors of classroom cooperating teachers as perceived by the cooperating teacher and the student teacher the study assessed the collaboration of the student teaching experience. The comparison was made after the completion of questionnaires by classroom cooperating teachers and their student teachers. The supervisory behaviors were categorized as directive, collaborative, or nondirective as measured by selection of statements in the areas of instructional planning, management, and evaluation. The results from the descriptive data collected in this study provide information on the existing supervisory behaviors of cooperating teachers.