This study focuses on developing a better comprehension of the mobility of lightweight autonomous vehicles with varying locomotion platforms on sand. This research involves four segments. The first segment is a review of military criteria for the development of lightweight unmanned ground vehicles, followed by a review a review of current methodologies for evaluating the terramechanic (vehicle-ground interaction) mobility measures of heavyweight wheeled and tracked vehicles, and ending with a review of the defining properties of deformable terrain with specific emphasis on sand. These present a basis for understanding what currently defines mobility and how mobility is quantified for traditional heavyweight wheeled and tracked vehicles, as well as an understanding of the environment of operation (sandy terrain) for the lightweight vehicles in this study. The second segment involves the identification of key properties associated with the mobility and operation of lightweight vehicles on sand as related to given mission criteria, so as to form a quantitative assessment system to compare lightweight vehicles of varying locomotion platforms. A table based on the House of Quality shows the relationships—high, low, or adverse—between mission profile requirements and general performance measures and geometries of vehicles under consideration for use. This table, when combined with known values for vehicle metrics, provides information for an index formula used to quantitatively compare the mobility of a user-chosen set of vehicles, regardless of their methods of locomotion. This table identifies several important or fundamental terramechanics properties that necessitate model development for robots with novel locomotion platforms and testing for lightweight wheeled and tracked vehicles so as to consider the adaptation of counterpart heavyweight terramechanics models for use. The third segment is a study of robots utilizing novel forms of locomotion, emphasizing the kinematics of locomotion (gait and foot placement) and proposed starting points for the development of terramechanics models so as to compare their mobility and performance with more traditional wheeled and tracked vehicles. In this study several new autonomous vehicles—bipedal, self-excited dynamic tripedal, active spoke-wheel—that are currently under development are explored. The final segment involves experimentation of several lightweight vehicles and robots on sand. A preliminary experimentation was performed evaluating a lightweight autonomous tracked vehicle for its performance and operation on sand. A bipedal robot was then tested to study the foot-ground interaction with and sinkage into a medium-grade sand, utilizing a one of the first-developed walking gaits. Finally, a comprehensive set of experiments was performed on a lightweight wheeled vehicle. While the terramechanics properties of wheeled and tracked vehicles, such as the contact patch pressure distribution, have been understood and models have been developed for heavy vehicles, the feasibility of extrapolating them to the analysis of light vehicles is still under analysis. A wheeled all-terrain vehicle was tested for effects of sand gradation, vehicle speed, and vehicle payload on measures of pressure and sinkage in the contact patch, and preliminary analysis is presented on the sinkage of the wheeled all-terrain vehicle. These four segments—review of properties of sandy terrain and measures of and criteria for the mobility of lightweight vehicles operating on sandy terrain, the development of the comparison matrix and indexing function, modeling and development of novel forms of locomotion, and physical experimentation of lightweight tracked and wheeled vehicles as well as a bipedal robot—combine to give an overall picture of mobility that spans across different forms of locomotion. / Master of Science

Portable Free Fall Penetrometers (PFFPs) are lightweight tools used for rapid and economic characterization of surficial subaqueous sediments. PFFPs vary in weight, shape and size with options for using add-on units. The different configurations enable deployments in various environments and water depths, including the nearshore zone where conventional methods are challenged by energetic hydrodynamics and limited navigable depth. Moreover, PFFPs offer an opportunity to reduce the high site investigation costs associated with conventional offshore geotechnical site investigation methods. These costs are often a major obstacle for small projects serving remote communities or testing novel renewable energy harvesting machines. However, PFFPs still face issues regarding data analysis and interpretation, particularly in energetic sandy nearshore areas. This includes a lack of data and accepted analysis methods for such environments. Therefore, the goal of this research was to advance data interpretation and sediments characterization methods using PFFPs with emphasis on deployments in energetic nearshore environments. PFFP tests were conducted in the nearshore areas of: Yakutat Bay, AK; Cannon Beach, AK; and the U.S. Army Corps of Engineers' Field Research Facility's beach, Duck, NC. From the measurements, the research goal was addressed by: (1) introducing a methodology to create a regional sediment classification scheme utilizing the PFFP deceleration and pore pressure measurements, sediment traces on the probe upon retrieval, and previous literature; (2) investigating the effect of wave forcing on the sediments' behavior through correlating variations in sediment strength to wave climate, sandbar migration, and depth of closure, as well as identifying areas of significant sediment mobilization processes; and (3) estimating the relative density and friction angle of sand in energetic nearshore areas from PFFP measurements. For the latter, the field data was supported by vacuum triaxial tests and PFFP deployments under controlled laboratory conditions on sand samples prepared at different relative densities. The research outcomes address gaps in knowledge with regard to the limited studies available that investigate the sand geotechnical properties in energetic nearshore areas. More specifically, the research contributes to the understanding of surficial sediment geotechnical properties in energetic nearshore areas and the enhancement of sediment characterization and interpretation methods. / PHD

In the past several decades there has been an increased interest in sand, dust, and ash particulates ingestion study for gas turbine engine applications. Recently, there has been an increase in commercial and military fleets operating in medium to highly dusty environments, such as areas in Africa, the Middle East, and Asia. Dusty environments can cause blockage in turbine cooling circuits which can lead to early engine maintenance or removals. Ingested debris can melt, forming glassy or molten deposits on various hot section components in gas turbine engines. This thesis evaluates the onset of deposit formation using an experimental rig to perform testing in high temperature environment. In general, deposits on turbine components can affect the operating capacity and the overall operating efficiency of gas turbine engines. Particulate ingestion events can be catastrophic and cost millions of dollars in maintenance and repairs. The experimental work in this thesis focused only on quantifying the initial deposit formation in high temperature environment to aid in the development of resilient engine design and operational diagnostics. Testing was performed using HASTELLOY® X coupons and Arizona Road Dust with main gas flow temperatures between 1050°C and 1100°C. Arizona Road Dust sample with sizing between 2µm and 40µm were used for experimental testing. The sensitivity of the initial deposit formation on cooled HASTELLOY® X coupon surface was investigated by using an inline air heater. Three cooling test conditions: no cooling, 500°C cooling, and 250°C cooling, were used to alter the surface temperature of the coupon during testing. Results from testing indicated cooling test conditions used have a small impact on deposit formation. / Master of Science

In the nineteenth century, amidst the rise of anti-Catholicism in the Western world, narratives served as a persuasive medium to influence the reading public. Anti-clerical sentiment was conveyed in various forms of text, often depicting the Catholic convent as a place of sinister confinement. This thesis offers an alternative representation of the French nineteenth-century convent. Considering the prevailing social, economic, and political environment in France, along with the conception of social space, I argue that the convent represents a place of sanctuary and opportunity for some women and girls. Further, in view of Victor Hugo's Les Misérables, I examine the representation of the convent as a place for rebirth. Likewise, in analyzing George Sand's autobiography Histoire de ma vie, I explore the representation of the convent as a haven for reviving creativity. Thus, by close reading and critical examination of these literary representations, I contend that the nineteenth-century convent can provide a place of refuge. / Master of Arts / Following the French Revolution of 1789, two opposing ideologies gathered momentum in France: monasticism and anti-clericalism. Beginning in 1815, enlistment of nuns in religious congregations doubled every fifteen years until the end of the century. During this period, anti-clericalism remained a potent political and social force. As with any institution of power, narratives served as a persuasive medium to influence the reading public. Anti-clerical sentiment was conveyed in various forms of text, often depicting the Catholic convent as a place of sinister confinement. These diverse depictions of the convent as a nefarious enclosure seem to contradict the growth and appeal of female religious orders during the epoch. This thesis offers an alternative representation of the French nineteenth-century convent. Partially owing to prevailing social, economic, and political structures that limited women's opportunities, convents attracted women from middle- or upper-class families who desired to serve in the public domains of healthcare and education. Considering this environment in France, along with the conception of social space, I argue that the convent represents a place of sanctuary and opportunity for some women and girls. Further, in view of Victor Hugo's Les Misérables, I examine the representation of the convent as a place for rebirth. Likewise, in analyzing George Sand's autobiography Histoire de ma vie, I explore the representation of the convent as a haven for reviving creativity. Thus, by close reading and critical examination of these literary representations, I contend that the nineteenth-century convent can provide a place of refuge.

The overall goal of this work is to improve the structural performance of cellular structures in bending applications by incorporating tensegrity behavior using long continuous fibers. The designs are inspired by the hierarchical cellular structure composition present in pomelo fruit and the structural behavior of tensegrity structures. A design method for analyzing and predicting the behavior of the structures is presented. A novel manufacturing method is developed to produce the cellular structures with tensegrity behavior through the combination additive manufacturing and metal casting techniques. Tensegrity structures provide high stiffness to mass ratio with all the comprising elements experiencing either tension or compression. This research investigates the possibility of integrating tensegrity behavior with cellular structure mechanics and provides a design procedure in this process. The placement of fibers in an octet cellular structure was determined such that tensegrity behavior was achieved. Furthermore, using finite element analysis the bending performance was evaluated and the influence of fibers was measured using the models. The overall decrease in bending stress was 66.6 %. Extending this analysis, a design strategy was established to help designers in selecting fiber diameter based on the dimensions and material properties such that the deflection of the overall structure can be controlled. This research looks to Additive Manufacturing (AM) as a means to introduce tensegrity behavior in cellular structures. By combining Binder Jetting and metal casting a controlled reliable process is shown to produce aluminum octet-cellular structures with embedded fibers. 3D-printed sand molds embedded with long continuous fibers were used for metal casting. The fabricated structures were then subjected to 4 point bending tests to evaluate the effects of tensegrity behavior on the cellular mechanics. Through this fabrication and testing process, this work addresses the gap of evaluating the performance of tensegrity behavior. The overall strength increase by 30%. The simulation and experimental results were then compared to show the predictability of this process with errors of 2% for octet structures without fibers and 6% for octet structures with fibers. / Master of Science

Gas turbines for military applications, when operating in harsh environments like deserts often encounter unexpected operation faults. Such performance deterioration of the gas turbine decreases the mission readiness of the Air Force and simultaneously increases the maintenance costs. Some of the major factors responsible for the reduced performance are ingestion of debris during take off and landing, distorted intake flows during low altitude maneuvers, and hot gas ingestion during artillery firing. The focus of this thesis is to study ingestion of debris; specifically sand. The region of interest being the internal cooling ribbed duct of the turbine blade. The presence of serpentine passages and strong localized cross flow components makes this region prone to deposition, erosion, and corrosion (DEC) by sand particles. A Lagrangian particle tracking technique was implemented in a generalized coordinate multi-block Navier-Stokes solver in a distributed parallel framework. The developed algorithm was validated by comparing the computed particle statistics for 28 microns lycopodium, 50 microns glass, and 70 microns copper with available data [2] for a turbulent channel flow at Ret=180. Computations were performed for a particle-laden turbulent flow through a stationary ribbed square duct (rib pitch / rib height = 10, rib height / hydraulic diameter = 0.1) using an Eulerian-Lagrangian framework. Particle sizes of 10, 50, and 100 microns with response times (normalized by friction velocity and hydraulic diameter) of 0.06875, 1.71875, and 6.875 respectively are considered. The calculations are performed for a nominal bulk Reynolds number of 20,000 under fully developed conditions. The carrier phase was solved using Large Eddy Simulation (LES) with Dynamic Smagorinsky Model [1]. Due to low volume fraction of the particles, one-way fluid-particle coupling was assumed. It is found that at any given instant in time about 40% of the total number of 10 micron particles are concentrated in the vicinity (within 0.05 Dh) of the duct surfaces, compared to 26% of the 50 and 100 micron particles. The 10 micron particles are more sensitive to the flow features and are prone to preferential concentration more so than the larger particles. At the side walls of the duct, the 10 micron particles exhibit a high potential to erode the region in the vicinity of the rib due to secondary flow impingement. The larger particles are more prone to eroding the area between the ribs and towards the center of the duct. At the ribbed walls, while the 10 micron particles exhibit a fairly uniform propensity for erosion, the 100 micron particles show a much higher tendency to erode the surface in the vicinity of the reattachment region. The rib face facing the flow is by far the most susceptible to erosion and deposition for all particle sizes. While the top of the rib does not exhibit a large propensity to be eroded, the back of the rib is as susceptible as the other duct surfaces because of particles which are entrained into the recirculation zone behind the rib. / Master of Science

The Cone Penetration Test (CPT) was developed originally in Holland in the 1930’s as a device which provides a small scale model of a pile foundation. Early versions were simple cone points for which the only measurement was the thrust required to push the point through the ground. Over the past 20 years, the cone was standardized to a tip area of 10 cm², and an electrical version was produced, which allows for continuous measurement of the cone tip resistance and sleeve friction along with a computer-based data acquisition system. The electrical cone represents a significant step forward for the CPT, since it provides a continuous profile of information that can be used to identify soil type and define important engineering parameters. More recently, the CPT has shown considerable potential for calculation of settlements of footings on sand, determination of pile capacity, assessment of ground pressures, and evaluation of liquefaction potential for cohesionless soils. Along with the widening application of the CPT, new varieties of cone penetrometers have appeared, with different sizes than the standard. Smaller cones are used for instances where relatively small depths of soil need to be penetrated, and larger cones have been developed for penetrating dense and gravelly soils. With the introduction of the new cones, there has been a tendency to assume that the methods for reducing CPT data for the standard sized cone can be extrapolated to the other sizes of cones. That is, it is assumed that there are no scale effects in cones of different sizes. While this may be true, to date, little direct evidence has been produced to support this view, and the issue is an important one from two points of view: 1. The present data analysis technology is based on that primarily from testing with a standard cone. lt is important to know if any changes are needed in this approach, or if the existing methods can be used with confidence for any size cone. 2. If it can be shown that no scale factor exists, then this will allow the use of new, smaller cones in experimentation in modem calibration chambers with the knowledge that the test results are applicable for the cones that a.re more widely used in practice. The smaller cones offer several advantages in this type of work in that they facilitate the research considerably by reducing the effort involved in sample preparation, and they are less likely to produce results influenced by boundary conditions in the chamber. One of the major objectives of this research is to develop an insight into the issue of the scale factor caused by the use of different sizes of cones. This is accomplished through an experimental program conducted in a new large scale calibration chamber recently constructed at Virginia Tech. Many of the latest developments in cone penetration testing have been forthcoming from testing done in calibration chambers where a soil mass can be placed to a controlled density under known stress conditions. To conduct the experimentation of this work, it was necessary to design, fabricate, and bring to an operational stage a calibration chamber. The Virginia Tech chamber is one of the largest in the world. A significant portion of the effort involved in this thesis research was devoted to this task. In particular, attention was devoted to the development of a system for placement of a homogeneous soil mass in the chamber, and the implementation of a microcomputer-based data acquisition unit to record and process the test results. The scale effects investigation was performed using three different sizes of cone penetrometers in a test program conducted in the calibration chamber. Of the three cones, one is smaller than the standard with a tip area of 4.23 cm², one was a standard cone with a tip area of 10 cm², and one was larger than the standard cone with a tip area of 15 cm². A total of 47 tests were carried in the chamber using two different levels of confining stress and two different sand densities. The test results show that while a scale factor might exist, the degree of its influence on interpreted soil parameters for a practical problem does not appear significant. / Ph. D. / incomplete_metadata

Economic development is one of the main objectives of developed and developing nations worldwide. Development comes with growth of urban areas. Urban growth is achieved through sand and gravel mining for construction of modern, attractive and durable structures. The study examined positive and negative environmental impacts of the continuous removal of river sand, pit sand and gravel from sampled rivers and open areas surrounding Gaborone developing Central Business District, malls and private properties in city. Quantitative and qualitative research designs that is questionnaire survey, oral interviews, field observation and measurements were used to collect data from selected sampled points. Metsimotlhabe and Ditlhakane rivers were selected because they are nearer to Gaborone and most river sand is mined from these rivers. More points were sampled from open areas in Kumakwane, Kopong and Bela Bela farms where pit sand and gravel are mined. Convenience and purposive sampling methods were used to pick questionnaire survey respondents (175) from Kumakwane and Metsimotlhabe villages where people affected lives. Findings of the study highlighted that river sand was mined most from rivers near Gaborone compared to pit sand and gravel because of its multi uses. Mining is important for economic development, to construct durable, modern structures, employment creation and revenue collection but removal of river sand leads to deepening and widening of rivers. Artificial rivulets are formed as resource is extracted uncontrollably. Pit sand and gravel are extracted from open areas creating uncovered deep pits, which caused of accidents to children and livestock. Erosion and environmental degradation occur due to continuous mining. Miners dispose waste on open areas and riverbeds causing land pollution. Dust and noise pollution from tipper trucks ferrying sand and gravel are a cause of concern to villagers as the trucks move even at night, disturbing sleep. Solutions to uncontrolled mining include 24 hour security and regular raids on illegal miners. The author recommends that heavy penalties should be imposed to curb illegal mining. High level decision making forum involving all stakeholders is necessary to discuss problems of illegal mining and how to limit negative impacts. Department of Mines need to develop an Environmental Management Plan and a close monitoring program nationwide. / Environmental Sciences / M. Sc. (Environmental Management)

Dans la présente étude intitulée « Une approche transnationale des écritures des femmes ottomanes et françaises (européennes) au 19ème et au début du 20ème siècle » nous avons étudié les ouvrages et œuvres de femmes ottomanes et européennes autour de l’image du « harem » avec une approche transnationale féministe. La revendication de la thèse est que l’on ne peut ni parler d’une seule image du harem ni d’un type de récit de harem de femme ottomane, anglaise ou française. En replaçant ces ouvrages, classés dans la catégorie de « littérature de harem » au rang de la littérature mondiale, nous avons observé les différentes manières d’appréhender la lutte pour la libération de la condition féminine des femmes ottomanes comme autant de témoignages différents. D’autre part, nous avons mis en évidence, les interactions et la solidarité que les femmes féministes ottomanes et européennes ont mis en place, malgré les différences, de race, langue et religion pour leur lutte pour la condition féminine, dans un commun état d’esprit lié aux revendications de leur genre, du 19ème siècle au début du 20ème siècle. / In this manuscript titled « A Transnational Approach to Literatures of Ottoman and French (European) Women Writers of 19th and Early 20th Centuries » works of Ottoman and European women writers gathered around the image of « harem » are explored with a comparative and transnational feminist method. Their work is analyzed in a non-Eurocentric, transnational, multi-cultural and multi- lingual, global and systematic perspective divorced from discourses of male hegemony. The central argument of this manuscript is that there are multiple images for the East and hardly any type of European women’s narrative can serve as a prototype. In this study, narratives piled under the category « harem literature » are evaluated as part of the greater World Literature and arenas for contrasting testmonies of Ottoman Women’s Liberation Movement. Moreover, solidarity and interaction developed among Ottoman and European women are noted who had common gender-related problems next to differences due ethnicity, language and religion, in the 19th and early 20th centuries.

Cette thèse intitulée « Esthétique et poétique des jardins : entre art et science, parcours et discours dans la fiction sandienne» vise à étudier la place qu’occupe le jardin essentiellement dans les romans, contes et nouvelles de George Sand. L’enjeu de cette recherche est de démontrer que le jardin chez Sand ne se réduit pas à un simple arrière-plan, à un élément de fioriture, ou à une pure thématique. Il revêt au contraire chez l’auteure une ampleur considérable allant jusqu’à devenir un objet spéculatif capable de repenser tout à la fois les genres et les esthétiques et de susciter de riches réflexions en rapport avec l’art (peinture, architecture, dessins) et la science (botanique, écologie, horticulture, minéralogie) au XIXe siècle. Le jardin occupe aussi une place de choix dans l’œuvre de Sand en vertu de ses diverses fonctions diégétiques, poétiques et symboliques au sein de la diégèse, mais aussi en raison de son aptitude à être un lieu de cheminement au sein duquel le promeneur peut se promettre divers plaisirs et évolutions. Le jardin devient en ce sens un monde complet en soi, un lieu riche et influent, un véritable creuset de signes et de significations dont se sert l’auteure pour véhiculer son idéologie, ses goûts esthétiques, ses pensées intimes, son idéalisme, ainsi que sa philosophie de la vie / This thesis entitled "esthetic and poetic of gardens: between art and science, path and speech in Sandian fiction" aims to study the place of garden especially in novels, tales and short stories of George Sand. The challenge of this research is to prouve that the garden for Sand is not just a backdrop, an element of flourish, or a pure topic. In contrast, it takes on a considerable scale in the author's work, even becoming a speculative object able to rethink genres and esthetics at the same time and generating rich reflections related to art (painting, architecture, drawings) and science (botany, ecology, horticulture, mineralogy) in the 19th century. The garden occupies a prominent place in the work of Sand due to its various diegetic, poetic and symbolic functions within the diegesis, but also because of its aptitude to be a pathway within which the walker can promise himself various pleasures and evolutions. The garden becomes in that way, a complete world by itself, a rich and impactful place, a veritable crucible of signs and meanings that the author uses to convey her ideology, her esthetic preferences, her intimate thoughts, her idealism, as well as her life philosophy