The existence of small surface discontinuities on a flow surface generate significant pressure fluctuations which can manifest as radiated far field sound and affect the fluctuating near wall pressure field exerted on the flow surface. A significant amount of research has been performed on various step and gap flows; however few have dealt with step heights that are small relative to the incoming boundary layer. Fewer still have been concerned with measuring the effect on the fluctuating wall pressure field or the radiated far field sound from these small surface discontinuities. This study presents the work aimed at scaling the radiated sound from small forward and backward steps, detailing the surface pressure field as a result of these steps, and detailing the far field sound radiated from gap configurations of similar dimension. These measurements were performed in the Virginia Tech Anechoic Wall Jet facility for step heights that ranged from approximately 10% to 100% of the incoming boundary layer height. The results show the influence of step height and boundary layer velocity on the far field sound from forward and backward steps. Very little directivity is seen for either source and the larger step heights considered in this study are shown to not be acoustically compact. A new mixed scaling normalization is proposed for the far field spectra from both types of step, which is shown to reliably collapse the data. Backward steps are shown to be much weaker producers of far field sound than a similarly sized forward step. The implications of this behavior are discussed with respect to the far field sound measured from various gap flows. The fluctuating wall pressure field was measured upstream and downstream of both step configurations. The data shows a slow recovery of the wall pressure field with lasting disturbances up to 100 step heights downstream of the step feature. / Master of Science

Trailing edge noise is a common noise source in aerodynamic applications, such as wind turbines, duct fan blades, and propellers. As sound is a nuisance for people near this machinery, methods of reducing trailing edge noise are being investigated. A proven method of trailing edge noise reduction is using a serrated trailing edge. Many prior experiments have shown that a trailing edge with sawtooth serrations can reduce trailing edge noise compared to a straight trailing edge, but the mechanism by which sawtooth serrations reduce noise is not fully understood. Previous theoretical models have assumed that the turbulence field convecting past a serrated trailing edge is unchanged by the presence of the serrations, but experiments have shown that this is not the case in reality. This work attempts to further explore the mechanisms behind why trailing edge serrations reduce trailing edge noise. Additionally, it evaluates the usefulness of a wall jet wind tunnel for use in the study of serrated trailing edges. Experiments were conducted in an anechoic wall jet wind tunnel using a straight trailing edge configuration and a serrated trailing edge configuration. It was found that there may be differences in the unsteady surface pressure over serrated edges in one-sided flows as compared to two-sided flows, like on that of an airfoil, most notably in relation to the magnitude of the unsteady pressure on the serrations. In the wall jet and in agreement with other studies, it was found that the unsteady pressure fluctuations increase towards the tip of the serration in one-sided flows. This is counter to what is found in some studies of two-sided flows. Good agreement was found between some models of the wavenumber-frequency wall pressure spectrum of a turbulent boundary layer and the measured wall pressure spectrum on the straight trailing edge, and these models also produced good predictions of the noise produced by this trailing edge using Amiet's equation. A surface pressure microphone array was used to estimate the zero spanwise wavenumber surface pressure spectrum. This spectrum was used in Amiet's method to predict the measured trailing edge noise. Predictions using the wavenumber-filtered measurement tended to overpredict the measured far field noise most likely due to the inclusion of broader wavenumber content through the array's side lobe response and the breadth of the main lobe. The serrated trailing edge was found to increase coherence between two points on the same serration while reducing coherence between two points on different serrations. It was concluded that the presence of the serrations decorrelates small-scale turbulent eddies. Additionally, it was found that while the serrated trailing edge did reduce the noise produced, its destructive effect on the geometry-based resonance of the straight trailing edge configuration may have amplified the magnitude of the reduction. Finally, it was concluded that the serrations do indeed affect the hydrodynamic field near the trailing edge, and the theoretical models which make the assumption otherwise must be refined. / Master of Science / Trailing edge noise is a common noise source in aerodynamic applications, such as wind turbines, duct fan blades, and propellers. As sound is a nuisance for people near this machinery, methods of reducing trailing edge noise are being investigated. A proven method of trailing edge noise reduction is using a serrated trailing edge. Many prior experiments have shown that a trailing edge with sawtooth serrations can reduce trailing edge noise compared to a straight trailing edge, but the mechanism by which sawtooth serrations reduce noise is not fully understood. This work attempts to further explore the mechanisms behind why trailing edge serrations reduce noise. Experiments were conducted in an anechoic wind tunnel facility. It was found that a one-sided flow over a serrated trailing edge may be significantly different from that over a two-sided flow. Good agreement was found between prediction models and measurements of trailing edge noise. The serrated trailing edge was effective at reducing the coherence of turbulent eddies across the roots of the sawtooth serrations. It was concluded that the serrated trailing edge is effective at reducing noise, and that one means of doing so is decreasing the correlation of small-scale turbulent eddies, and that current models of the flow over serrations may need to be refined.

This thesis began as an exploration of the idea of home, a study that revealed the importance of place. Seeking to understand what makes a successful place, I studied neighborhoods with which I was familiar, identifying characteristics of both the vital and the lifeless. As a foundation for architectural exploration, this study helped me to recognize the dynamic qualities of denser, more urban neighborhoods, and to establish rowhousing as the vehicle through which to undertake my exploration of urban living. While providing the genesis for the project and further defining certain elements as worthy of further study, this initial exploration was nonetheless lacking. I had to do more than just speak of the conditions I hoped to achieve and of the characteristics of the elements with which to make the conditions manifest. I had to make the conditions, make the elements. It was essential for me to establish a clear order, so that these conditions could be brought together to form a cohesive whole. I was able to arrive at a fully conceived expression of the project by structuring the conditions that I identified through the application of three dimensional grids. The interrelationships among the grids helped structure the relationships among various conditions, ensuring that they enhanced one another, and were, in fact, stronger together than separately. Working with the grids taught me that in order for them to be effective regulators the grids had to be intelligible while still being flexible; that they should help define but never dictate. It exposed the tension between the regulating devices we, as architects, utilize as tools for design and the three-dimensional material with which the designs are constructed, as well as the obligation of reconciling the two. Not only must the device accommodate the material and the material reveal the device, but indeed all facets of the design must be considered in relation to one another and to the whole. When philosopy, device, and material work in service of one another the possibility for architectural expression rather than simple building is created. One does not revere great architects solely for their philosophies of design, the functionality of the spaces they create, the materials with which they construct them, or the regulating devices they employ, but rather for the complexity with which these elements are brought together to form a whole so well designed that it seems that it could have been done no other way. / Master of Architecture

this thesis is an exploration of rational architectural forms and urban ideas. reflections of density, circulation, rhythm, pattern, and punctuation. the formal consequence of two ideas, city and spectacle, manifest in a theatre for the acrobatic performing arts. on the exterior, an autonomous construction where the architecture is a confrontation to the urban world. internally, a world where spectator and spectacle exist playfully through drawing, modeling, and collage. the project brings the structure of the city to the structure of the theatre. theatre as analogy, a city turned inward. / Master of Architecture

The purpose of this book is to explore the idea of duration of physical architectural elements, and how their relative permanence or temporariness affects time and memory. This project takes on the program of a healthcare facility in the community of Verón located in the Dominican Republic. Through the exploration of materials, the identity of the project is defined by a series of walls that bring order and scale to not only the clinic but the surrounding community as well. / Master of Architecture

Two primary ideas contribute to the design of this Community Art Center in the city of Milwaukee, Wisconsin, particularly, in the neighborhoods of Avenue west and Midtown. The quality of light expressed through the movement of shadows in time is casted in the interior by openings in the roof and on the exterior walls by columns surrounding the building. These exterior and interior walls of the building are the result of rigorous experimentation to maximize space for interaction. The walls and quality of light is expressed both in the interior and exterior of the building. The second main idea is center around creating a place for interaction to generate communication and collaboration within the community. The primary design is of the delicate undulating walls as it continues to define interaction space in the Community Art Center. It is the form of the walls and quality of light that express movement. As a secondary concern, these neighborhoods are on the edge of Milwaukeeâ s near west side that includes the Milwaukee High School of the Arts (MHSA). The community expresses art in the form of dance, music and creative writing. The building express art in the form of a decision. Each decision that is made expresses a quality about design. Each space is transformed into a place by the nature of its design. The building achieves a sense of community through the primary ideas expressed through the notion of emotions. / Master of Architecture

No / This paper presents a numerical modelling method to predict the shear behaviour of typical wall-stud cold-formed steel wall panels subjected to in-plane monotonic loads. In the research presented in this paper, different material and mechanical properties for cold-formed steel sheets, self-drilling screwed connectors and wall fixing boundary conditions were considered to explore the influence of sheath sheeting, connectors and fixing boundary conditions on the structural behaviour of selected wall panels. After the FE model being validated against experimental results, a parametric study was conducted and the comparison and analysis highlight the effect of different sheaths, connectors on to the structural shear behaviour of typical wall-stud cold-formed steel wall panels.

Yes / An approximation to the Phan-Thien Tanner (PTT) constitutive model is developed with the aim of giving low-cost simulation of Gas Assisted Injection Moulding (GAIM) while incorporating important viscoelastic characteristics. It is shown that the developed model gives a response typical of full viscoelastic models in transient and steady state uniaxial and constant shear rate deformations. The model is incorporated into a 3D finite element GAIM simulation which uses the ‘pseudo-concentration’ method to predict residual polymer, and applied to published experimental results for a Boger fluid and a shear-thinning polystyrene melt. It is shown that the simulation gives a very good match to published results for the Boger fluid which show increasing Residual Wall Thickness (RWT) with increasing Deborah number. Against the shear-thinning polymer, the quality of match depends upon which of two ‘plausible’ relaxation times is chosen; qualitatively different results arise from two different means of estimating a single relaxation time. A ‘multi-mode’ approach is developed to avoid this uncertainty. It is shown that the multi-mode approach gives decreasing RWT with increasing Deborah number in agreement with the published experimental results, and avoids the issues that arise from estimating a single relaxation time for a molten polymer.

Thesis (M.F.A.)--Boston University / PLEASE NOTE: Boston University Libraries did not receive an Authorization To Manage form for this thesis or dissertation. It is therefore not openly accessible, though it may be available by request. If you are the author or principal advisor of this work and would like to request open access for it, please contact us at open-help@bu.edu. Thank you. / This publication is the discussion and examination of work produced for the degree of Masters of Fine Arts in enameling and metal work. The body of work created consists of enameled brooches and wall panels. The thesis paper documents the technical and aesthetic developments in painting and metals as they pertain to the thesis work, and discusses the landscape subjects which so strongly influence the images that I create. The work produced for the thesis show is discussed in the manner in which it was conceived, as groupings; or as series. Methods of manipulating enamels for specific visual and textural results, various enamel finishes, and the use of enamel oxides are documented. Metal techniques employed as well as the framing method devised for the presentation of the wall panels are also documented. References and key incluences are painters and artists working in metalsmithing and jewelry. In the painting field Narcisse Diaz, Charles-Francois Daubigny, Eduard Vuillard and George Inness are nineteenth century artists who greatly influenced my artistic development. In the metals field Charles Loloma, Georg Jensen and Rene Lalique are influences which established the foundations of my ideas and tastes in my jewelry . While at graduate school the work and teachings of enamelists Jamie Bennett and William Hellwig initiated the interests I developed for enameling. The paper is essentially an indepth analysis of the way in which I perceive my work, what I want to communicate to the viewer, and how and why I create the kinds of objects that I do. / 2999-01-01

Doctor of Philosophy / This study emphasizes the need to incorporate sustainable practices into urban planning in Saudi Arabia, therefore helping the country's Vision 2030 goals for a greener future. The research focuses on developing a framework for constructing beautiful wall panels using recycled materials, which is critical for solving energy and environmental issues. By integrating several research methodologies, the study creates an initial framework that is subsequently refined with expert feedback. The findings suggest that employing recycled materials for these wall panels not only improves their beauty but also helps to create a more sustainable and environmentally responsible approach to building in Saudi Arabia. This study's findings provide architects and designers with practical suggestions to assist them in creating more sustainable construction practices in the region.