Now showing items 14312-14331 of 14994

    • Ultimate flexural strength of flat slabs: with particular attention to membrane action

      Sakolosky, John Joseph, 1941- (The University of Arizona., 1966)
    • Ultimate performance limitations of phase-locked loops

      Paul, William Vincent, 1928- (The University of Arizona., 1961)
    • Ultimate shear strength of footings and flat plates

      Lawrence, Patrick Edward, 1940- (The University of Arizona., 1965)
    • Ultimate strength design of R/C columns by numerical integration method

      Yeung, David Ho-Fung, 1946- (The University of Arizona., 1975)
    • Ultra-compact Integrated Silicon Photonics Balanced Coherent Photodetectors

      Fallahi, Mahmoud; Meyer, Jason T.; Norwood, Robert A.; Pau, Stanley (The University of Arizona., 2016)
      The design, simulation, and initial fabrication of a novel ultra-compact 2x2 silicon multimode-interference device evanescently coupled to a dual germanium metal-semiconductor-metal (MSM) photodetector is presented. For operation at the standard telecom wavelength of 1.5 µm, the simulations demonstrate high-speed operation at 30 GHz, low dark current in the nanoamp range, and external quantum efficiency of 80%. Error analysis was performed for possible tilt error introduced by hybrid integration of the MSM layer on top of the MMI waveguides by use of surface mount technology (SMT) and direct wafer bonding.
    • Ultra-precise measurement of thermal expansion coefficients

      Bradford, James N., 1926- (The University of Arizona., 1969)
    • Ultra-violet light and titanium dioxide catalyzed oxidation of red dye-79

      Sierka, Raymond A.; Adharapurapu, Krishna, 1965- (The University of Arizona., 1991)
      This research focused on the color destruction of red dye-79 in aqueous solution. Red dye-79 is a typical pollutant in the textile industrial wastewater streams. A 50 parts per million (ppm) aqueous solution of this dye was used for all experiments. Although, there are many conventional techniques for the treatment, the research investigated a new methodology, which uses the synthetic ultraviolet radiation (254 nanometers) in combination with an undoped semi-conductor powder titanium dioxide (TiO₂) anatase for the photo-catalytic destruction of inorganics and organic moieties responsible for color in aqueous solution of red dye-79. Also, investigated were the effects of the oxidant hydrogen peroxide (H₂O₂) added externally to enhance the reaction kinetics for color destruction. Ultraviolet absorbance readings at 512 nanometers were employed to quantify the color destruction. The effects of reaction parameters catalyst (TiO₂), oxidant (H₂O₂), alkalinity and, dye concentrations as well as pH, on dye destruction kinetics were also quantified.
    • Ultrafine Bubble-Enhanced Ozonation For Water Treatment

      Livingston, Peter; Slack, Donald; Hung, Isaac; Yitayew, Muluneh (The University of Arizona., 2016)
      Ultrafine bubbles, often referred to as nanobubbles, have been used in various applications from environmental remediation to medicine. Even though the technology to generate ultrafine bubbles has been around for many years, the full potential of its applications has not been completely studied. This project seeks to study the use of ultrafine bubble technology for water treatment in combination with ozone gas. A factorial design experiment was chosen to test the effects of ultrafine bubbles on the concentration of an indicator organism, E. coli, in water as well as their effects on ozone gas being injected into water. Ozone gas or nitrogen gas was injected into water contaminated with E. coli as either ultrafine bubbles or fine bubbles as treatments for up to 60 minutes. Ultrafine bubbles were found to not have any significant effect on the concentration of E. coli in water. However, ultrafine bubbles did provide benefits when used in conjunction with ozone gas that regular, fine bubbles did not provide. The benefits included allowing the concentration of dissolved ozone in the water to decrease at a slower rate as well as allowing more ozone to dissolve into water at a higher rate than conventional methods of bubbling in ozone. While in this particular set of experiments the concentration of dissolved ozone in water didn't surpass 2 mg/L, which didn't allow for rapid disinfection and treatment of water, it is believed that with a more powerful ozone generator better results can be achieved. This project demonstrates the benefits and potential of injecting ozone gas as ultrafine bubbles into water as a way to effectively and efficiently disinfect and treat water.

      McIntosh, Michael Philip. (The University of Arizona., 1982)
    • Ultrasonic transducer modeling in homogeneous and nonhomogeneous media

      Kundu, Tribikram; Lee, Joon Pyo (The University of Arizona., 2001)
      Ultrasonic transducer modeling is important and fundamental research for nondestructive testing of materials. Traditionally, in most nondestructive evaluation applications, the ultrasonic transducers are modeled as point sources generating spherical wave fronts, line sources generating cylindrical wave fronts, or planar surfaces generating plane wave fronts. In reality, the transducer front face has finite dimensions; it is neither point source nor planar source. This study shows how the ultrasonic field in the neighborhood of a transducer with finite dimension varies in homogeneous and nonhomogeneous media. In this thesis, the pressure variation in front of a transducer face is computed for the following three situations: (1) the transducer is immersed in a homogeneous fluid; (2) the transducer is near a fluid-fluid interface; and (3) the transducer is near a fluid-solid interface using Distributed Point Source Method For the nonhomogeneous fluid medium, both normal incidence and oblique incidence cases have been studied.
    • An ultrasound phased array system for intracavitary hyperthermia

      Mylrea, Kenneth C.; Buchanan, Mark Thomas, 1967- (The University of Arizona., 1992)
      Intracavitary ultrasound hyperthermia applicators have the potential to better heat certain tumor sites, especially in the pelvic region, than external techniques. To allow deep, controlled heating, an intracavitary phased array has been developed. The hardware required to drive the array was also developed; including amplifiers, phase shifters, power meters and matching circuits. The entire system is computer controlled and capable of driving up to 64 individual ultrasound transducers. This system was used to conduct acoustic field measurements and in vivo perfused kidney experiments with the phased arrays. These results show that these arrays focus as predicted, and are capable of controlling the heating field by electrically controlling the position of the focus.

      Takessian, Alex. (The University of Arizona., 1983)
    • Ultrastructure changes induced by Scutellonema brachyurum in roots of potato

      Schuerger, Andrew Conrad (The University of Arizona., 1981)
    • The ultrastructure of retinal development in the chicken

      Miller, Mahlon Frederick, 1940- (The University of Arizona., 1965)
    • Ultraviolet and ultrasound disinfection of a recycle irrigation water

      Hardcastle, Clavin Hunter,1959-; Sierka, Raymond A. (The University of Arizona., 1987)
      Disinfection of an irrigation recycle water is evaluated by an investigation divided into three phases. Phase I experiments investigates disinfection by ultraviolet light alone; Phase II examines ultrasound disinfection; and Phase III investigates combined effects of ultrasound and ultraviolet light. Phase III also evaluates unit process sequencing in order to optimize disinfection performance. Ultraviolet light produced an average microorganism inactivation of 85.4% following one minute of UV irradiation. The response became asymptotic at this point. Cell viability, measured by ATP concentration, was not reduced below 10% until 15 minutes of UV treatment. Ultrasonic treatment resulted in microorganism survivals ranging fram 66.4% (60 W/1 and 30 minutes of treatment) to 25.1% (350 W/1 and 30 minutes of treatment). Combined treatment processes produced comparable results to UV only disinfection schemes. Overall, a satisfactory level of disinfection was not attained using UV light or ultrasound. The lack of disinfection response was attributable to the presence of interfering water constituents.
    • The Umma Within The Umma. How Al-Qaeda In The Arabian Peninsula’s Inspire Magazine Defines Moral Boundaries

      Nassar, Maha T.; Tarantini, Lara; Hudson, Leila O.; Noorani, Yaseen (The University of Arizona., 2018)
      In analyzing the content of al-Qaeda in the Arabian Peninsula’s Inspire magazine, I argue that the concept of Imagined Moral Umma should be utilized. I define the Imagined Moral Umma as an imagined community whose boundaries are determined by the moral standards of its members. By means of utilizing this framework, this thesis shows how AQAP creates a finite umma within a (virtually) infinite umma. Furthermore, this thesis shows firstly that the boundaries of this Imagined Moral Umma are flexible: inclusion and exclusion from this community depend upon historical contingencies. Secondly, the concept of takfīr (excommunication from the Muslim community) becomes irrelevant in Inspire magazine’s justification of violence against Muslims. Thirdly, this thesis highlights the ideological shift within Inspire magazine from a chiefly anti-Western propaganda to an anti-imperialist rhetoric.
    • Un bilan de la Compétence Symbolique chez les Apprenants du Français Langue Seconde

      Knisely-Southerland, Kris; Gorham, Julia Anne; Price, Joseph; Dupuy, Beatrice (The University of Arizona., 2020)
      La notion de compétence est une idée pour laquelle il existe plusieurs conceptions dans le domaine de l’apprentissage et l’enseignement des langues secondes (L2). Depuis le travail de Chomsky (1965) sur la distinction entre la compétence et la performance, les chercheurs ont été nombreux à formuler de nouvelles définitions de la compétence. On passe, alors de la compétence socioculturelle (Bourdieu, 1991) à la compétence interculturelle (Byram, 1997 ; Deardorff, 2009) et plus récemment à la compétence symbolique (Kramsch, 2006, 2009). Ce dernier concept souligne l’importance de la capacité des étudiants des L2 de reconnaître et de subvertir le pouvoir et la hiérarchie. Plus précisément, il s’agit de « the ability to manipulate symbolic systems, … and to position oneself to one’s benefit in the symbolic power game » ainsi que la capacité de réfléchir sur sa propre position dans le monde. Cette compétence, grâce à son emphase sur le pouvoir et la violence symbolique, est essentielle pour tout étudiant dans cette époque de « nouveau capitalisme » (Cope & Kalantzis, 2009). Il est alors surprenant que, malgré de multiples études précédentes conceptualisant la compétence symbolique au niveau théorique, on constate un manque important d’études examinant le côté pratique de celle-ci dans les cours de L2 et même plus son développement et son évaluation chez les apprenants du français. La littérature existante démontre néanmoins une relation entre la compétence symbolique et l’utilisation d’une approche pédagogique basée sur les littératies multiples et multimodales (Étienne et Vanbaelen, 2017 ; Kearney, 2010). Alors, l’étude présente vise à contribuer aux recherches cruciales sur ce sujet en répondant aux questions suivantes : 1) Est-ce que les étudiants démontrent des indices de la compétence symbolique en visionnant des films francophones, en complétant des questions d’analyse et en maintenant des journaux de réflexion et si oui, lesquels ? et 2) Quelles stratégies cognitives ou réflexionnelles sont utilisées par les étudiants, consciemment ou non, lorsqu’ils démontrent la compétence symbolique, s’ils en utilisent ? Afin de répondre à ces questions, des données ont été recueillies auprès de deux sections d’étudiants (N = 27) inscrits en quatrième semestre de français langue seconde à une grande université publique dans le sud-ouest des États-Unis en automne 2019. Une séquence pédagogique de multilittératies a été créée à partir de trois films francophones – Bienvenue chez les Ch’tis (2007), Bienvenue à Marly-Gomont (2016), et Divines (2016), choisis parce qu’ils abordent les thèmes de la diversité, l’altérité et l’identité. Les données récoltées comprennent des fiches de travail analytiques sur les trois films ainsi que des journaux de réflexion complétés par les étudiants et l’enseignante, des entretiens avec des étudiants consentants après la fin du semestre et des informations démographiques. Pour analyser ces données qualitatives, un processus consistant de trois cycles de codage, ouvert, axial et sélectif, a été adopté. Les résultats suggèrent que la compétence symbolique se manifeste souvent sous la forme des capacités de manipuler des biens symboliques (les émotions et expériences ainsi que les identités et affiliations), de créer de la complexité et d’analyser la forme et moins souvent sous la forme de la tolérance de l’ambiguïté. Ces indices se manifestaient lorsque les participants ont abordé une variété de stratégies largement classables dans trois catégories : les stratégies d’analyse, de réflexion, et d’écriture. Pour résumer, les résultats de cette étude indiquent que la vaste majorité des participants ont démontré au moins certains indicateurs de la compétence symbolique au fil des activités pédagogiques, ce qui suggère que celles-ci ont la capacité d’encourager les habilités supérieures de la pensée.