Tunable coaxial resonators based on silicon optical fibers

Thermal tuning of a coaxial fiber resonator with a silica cladding surrounding an inner silicon core is investigated. By pumping the silicon with below bandgap light, it is possible to redshift the WGM resonances

Performance of a new stator-diffuser design for an axial-flow pump unit

In an axial-flow pump unit with conventional stator and diftllser, often considerable energy is still present in the swirl (rotation) of the liquid leaving the stator. This energy will eventually be lost from the pump system. In this experimental investigation a new design, combining the stator and diffuser together into a single component, was tested for its effectiveness in recovering this energy and thereby improving the performance of an industrysized single-stage axial-flow pump unit. Measurements of static pressure rise along the new stator-difTuser and of the swirl angle of the fluid leaving the pump unit indicate that the new design performs better than the conventional one, as a component. However, efticiency of the whole pump unit is in general slightly reduced with the new design. A number of factors were identified as contributing to this performance degradation. Most notable are the poor matching of the fluid's and vanes' angles at the component's inlet and the sudden expansion of the flow geometry at the component's outlet. It is thus expected that when these factors have been adequately addressed, the new design should improve the pump's overall performance

Silicon Core Optical Fibre Production and Characterisation: An investigation of alkali earth metal oxide interface additives in a fibre production method.

Solid semiconductor optical fibres are of interest for infrared transmission and guided wave photonics. High transmission of light in the 2-6 micrometer wavelength region in optical fibres is difficult with today's materials, and the possibility of combining photonic and electronic components in one material has attracted much attention. This thesis presents a method of improving the quality of solid silicon core optical fibres made in a rapid draw process. It does this by the introduction of a alkali earth metal oxide interface modifier between the silica and the silcon core. This modifier acts as an in situ oxygen and metallic impurity getter. These investigations indicate that the interface layer forms a eutectic that reduces the stress caused by the expansion of silicon upon freezing. The silicon fibres made with this interface layer have greater mechanical flexibility than those without, but the optical losses are comparable to fibres made by other methods

Reflection, Calibration and Achievement In Introductory Calculus

Studies indicate that calculus acts as a filter for students entering into a STEM discipline, pushing some students to leave their field of study due to failure or disheartenment after going through the course. Since the demand for STEM-trained graduates grows, it is imperative to determine how to prevent more students from switching away from their STEM disciplines. The purpose of this project was to investigate whether the concept of calibration could increase student performance in introductory calculus in order to retain as many students as possible. This was a quasi-experimental study, conducted in calculus I and II courses, imploring CLEAR calculus, which is a nontraditional class style. Results indicated that in calculus I, with data from the first four classroom exams, the calibration could predict performance on the final exam. With calculus II, however, GPA was the only contributing factor to the final exam score. This implies that calibration may be more important in the first course, though further investigation is needed

An investigation into the nature and consequences of teachers' implicit philosophies of science

The aims of this study were to investigate the beliefs concerning the philosophy of science held by practising science teachers and to relate those beliefs to their pupils' understanding of the philosophy of science. Three philosophies of science, differing in the way they relate experimental work to other parts of the scientific enterprise, are described. By the use of questionnaire techniques, teachers of four extreme types were identified. These are: the H type or hypothetico-deductivist teacher, who sees experiments as potential falsifiers of hypotheses or of logical deductions from them; the I type or inductivist teacher, who regards experiments mainly as a way of increasing the range of observations available for recording before patterns are noted and inductive generalisation is carried out; the V type or verificationist teacher, who expects experiments to provide proof and to demonstrate the truth or accuracy of scientific statements; and the 0 type, who has no discernible philosophical beliefs about the nature of science or its methodology. Following interviews of selected teachers to check their responses to the questionnaire and to determine their normal teaching methods, an experiment was organised in which parallel groups were given H, I and V type teaching in the normal school situation during most of one academic year. Using pre-test and post-test scores on a specially developed test of pupil understanding of the philosophy of science, it was shown that pupils were positively affected by their teacher's implied philosophy of science. There was also some indication that V type teaching improved marks obtained in school science examinations, but appeared to discourage the more able from continuing the study of science. Effects were also noted on vocabulary used by pupils to describe scientists and their activities

Performance in Calculus II for students in CLEAR Calculus: A causal comparative study

Calculus is one of the greatest intellectual achievements of the world and is the main gateway for students that are heading into the fields that will power the economy of the 21st century. However, over 25% of students fail U.S. calculus courses each year and end up changing majors. It is important for educators and researchers to try to improve student success and find ways to increase STEM major retention. The purpose of this study was to compare the performance between students that are in traditional and non-traditional calculus II courses based on their preparation in either traditional or non-traditional calculus I. By the end of the study, non-traditional calculus II students performed approximately the same on every test and overall in the class. On the other hand, traditional calculus II students that took traditional calculus I performed better on the three tests, but their overall performance in the course was approximately the same as the students that took non-traditional calculus I

Students\u27 Perceived Utility of Precision Taught Calculus

The last decade of calculus research has showed students learn best when lecture is supplemented with thoughtful use of technology and group work; however, educators are given little direction of how they are to balance the already full first semester calculus class. Precision teaching is an instructional model that employs formative assessment to provide information on what topics are understood by students as well as indicate troublesome concepts. With this information, the instructor can adjust class time accordingly by incorporating supplemental activities most beneficial to students. The purpose of this interview study was to explore the perceived utility of precision teaching by eight students earning to see if further exploration of this topic was warranted. Although precision teaching requires more work for the instructor, students\u27 high perceived utility makes precision teaching a valuable method of undergraduate instruction because they claim to study more, understand material better, and earn higher grades

Before the Architecture of Humanism: Geoffrey Scott and the Hellenic Revival

Geoffrey Scott is today best remembered for his book-length contribution to the field of architectural criticism: The Architecture of Humanism: A Study in the History of Taste (1914/1924). Six years before the publication of this book, however, Scott published the Oxford Chancellor’s Prize-winning essay, The National Character of English Architecture (1908). In this, Scott articulated his privileging of Hellenic and humanist cultural and aesthetic values and applied his understanding of these to the elucidation of the architectural subject. Whilst today this essay is seldom studied, this dissertation posits that it is an important record of Scott’s life and preoccupations during his formative years, evidencing the mode by which classical humanism underpinned his appreciation of art, architecture, and aesthetic and moral values more broadly. Drawing on Scott’s written correspondence—and the correspondence of contemporaries including Mary Berenson and John Maynard Keynes—this dissertation identifies the formation of certain of Scott’s ideas not yet accounted for in the literature: his deference to classical Hellenism, and the concomitance of aesthetics, morality, and male homoeroticism for him between 1884 and 1908. This analysis is framed by the late nineteenth-century literary Hellenic revival at Oxford University; the Oscar Wilde trials of 1895; discourse on the “new persecution of peripheral sexualities” and constructions of “homosexuality” in Victorian era legal and medico-scientific frameworks; and, aestheticized and tacit understandings of homoeroticism encoded in newspaper reporting on homoerotically charged “scandals” of the time. Against this backdrop, the aesthetic-moral schema Scott encoded in his letters and in his essay, will be viewed as a call for “a new vision of life,” and understood as an attempt to reconcile the force of his aesthetic and homoerotic sensibilities with the strictures and prohibitions of the age in which he lived