Lygus hesperus is an important pest on different crops including cotton and alfalfa in the western U.S. Anaphes iole is a common parasitoid of Lygus spp. eggs in the U.S. and has potential as a biological control agent against L. hesperus in different crops. Its foraging behavior has been studied to a limited extent, but it is unknown whether A. iole females rely on plant volatiles to locate host habitats. L. hesperus feeding and oviposition are known to induce emission of plant volatiles in cotton and maize, but no studies have addressed the role of plant volatiles in the host searching behavior of A. iole. The objectives of this study were to evaluate the attraction of A. iole females toward volatiles derived from L. hesperus habitats and flight response of A. iole females toward cotton plants harboring L. hesperus eggs or treated with methyl jasmonate. Results from olfactometry bioassays showed that female wasps were attracted to odors emanating from different plant-L. hesperus complexes and from adult L. hesperus, while plants damaged by non-hosts or mechanically-damaged were not attractive. These findings suggested that A. iole females use specific plant volatiles released following L. hesperus feeding and oviposition to locate host habitats. In addition, in flight chamber tests A. iole females discriminated between cotton plants with moderate (41 eggs) and high (98 eggs) levels of L. hesperus infestations relative to uninfested plants, but not between plants with low (7 eggs) infestations compared to uninfested plants. In larger scale experiments conducted in the greenhouse, female wasps responded to L. hesperus-infested plants but not to methyl jasmonate-treated plants under similar conditions. Overall, results from this study revealed that A. iole females employ volatile signals to locate its host’s habitat and that they are attracted to plants damaged by L. hesperus feeding and oviposition. However, further research should seek to identify the chemical elicitors involved in the release of plant volatiles attractive to A. iole females.

Laminar turbulent transition is known for a long time as a critical phenomenon influencing the thermal load encountered by hypersonic vehicle during their planetary re-entry trajectory. Despite the efforts made by several research laboratories all over the world, the prediction of transition remains inaccurate, leading to oversized thermal protection system and dramatic limitations of hypersonic vehicles performances. One of the reasons explaining the difficulties encountered in predicting transition is the wide variety of parameters playing a role in the phenomenon. Among these parameters, surface roughness is known to play a major role and has been investigated in the present thesis. A wide bibliographic review describing the main parameters affecting transition and their coupling is proposed. The most popular roughness-induced transition predictions correlations are presented, insisting on the lack of physics included in these methods and the difficulties encountered in performing ground hypersonic transition experiments representative of real flight characteristics. This bibliographic review shows the importance of a better understanding of the physical phenomenon and of a wider experimental database, including real flight data, for the development of accurate prediction methods. Based on the above conclusions, a hypersonic experimental test campaign is realized for the characterization of the flow field structure in the vicinity and in the wake of 3D roughness elements. This fundamental flat plate study is associated with numerical simulations for supporting the interpretation of experimental results and thus a better understanding of transition physics. Finally, a model is proposed in agreement with the wind tunnel observations and the bibliographic survey. The second principal axis of the present study is the development of a hypersonic in-flight roughness-induced transition experiment in the frame of the European EXPERT program. These flight data, together with various wind tunnel measurements are very important for the development of a wide experimental database supporting the elaboration of future transition prediction methods.

No description available.

Buildings, maps and objects et cetera, can be modeled using a computer or reconstructed in 3D by data from different kinds of cameras or laser scanners. This thesis concerns the latter. The recent improvements of Time-of-Flight cameras have brought a number of new interesting research areas to the surface. Registration of several ToF camera point clouds is such an area. A literature study has been made to summarize the research done in the area over the last two decades. The most popular method for registering point clouds, namely the Iterative Closest Point (ICP), has been studied. In addition to this, an error relaxation algorithm was implemented to minimize the accumulated error of the sequential pairwise ICP. A few different real-world test scenarios and one scenario with synthetic data were constructed. These data sets were registered with varying outcome. The obtained camera poses from the sequential ICP were improved by loop closing and error relaxation. The results illustrate the importance of having good initial guesses on the relative transformations to obtain a correct model. Furthermore the strengths and weaknesses of the sequential ICP and the utilized error relaxation method are shown.

No description available.

This thesis presents a damage-tolerant flight control system design for propulsion-controlled aircraft (PCA). PCA refers to an emergency piloting strategy that flight crews use throttle modulation only to achieve the attitude control of aircraft in case of conventional flight control system failures. PCA also refers to a conceptual or experimental aircraft that is installed with such automated thrust-only control system. When an aircraft undergoes structural damage to its airframe, lifting or control surfaces which cause conventional control system failures, PCA is adopted as an alternative control approach to stabilize the aircraft. However, the control of the damaged aircraft poses complications in stability recovering as unmodeled uncertainties and perturbed dynamics have significant impact on flight dynamics. Therefore, the PCA flight control system should have a high level of robustness against such model uncertainties, aerodynamics parameter deviations, and model perturbations. This thesis presents the study of robust PCA control system design using H infinity-based robust control method. The developed controllers are tested through both linear and nonlinear simulations. A comprehensive evaluation is performed for several different emergency scenarios. The results demonstrate the advantages of the newly-designed robust flight control architecture over the existing optimal controller in dealing with model deviations due to structural damage.

The blended wing body (BWB) is a tailless aircraft with the potential to use 27% less fuel than a conventional aircraft with the same passenger capacity and range. The primary purpose of the current study was to determine the handling qualities of the BWB, using piloted-handling trials in a moving-base simulator. The secondary purpose was to determine the effect of simulator motion on handling-quality ratings. De Castro conducted piloted-handling trials in a fixed-base simulator. De Castro's tasks and flight model were modified in the current study. In the current study, three subjects rated the handling qualities as Level 1 or 2, depending on the task. Simulator motion did not have a significant effect on the results.

This thesis presents a damage-tolerant flight control system design for propulsion-controlled aircraft (PCA). PCA refers to an emergency piloting strategy that flight crews use throttle modulation only to achieve the attitude control of aircraft in case of conventional flight control system failures. PCA also refers to a conceptual or experimental aircraft that is installed with such automated thrust-only control system. When an aircraft undergoes structural damage to its airframe, lifting or control surfaces which cause conventional control system failures, PCA is adopted as an alternative control approach to stabilize the aircraft. However, the control of the damaged aircraft poses complications in stability recovering as unmodeled uncertainties and perturbed dynamics have significant impact on flight dynamics. Therefore, the PCA flight control system should have a high level of robustness against such model uncertainties, aerodynamics parameter deviations, and model perturbations. This thesis presents the study of robust PCA control system design using H infinity-based robust control method. The developed controllers are tested through both linear and nonlinear simulations. A comprehensive evaluation is performed for several different emergency scenarios. The results demonstrate the advantages of the newly-designed robust flight control architecture over the existing optimal controller in dealing with model deviations due to structural damage.

The last key to implementing laminar flow control on swept-wings is controlling the crossflow instability. One promising technology is spanwise-periodic discrete roughness elements (DREs). Previous work has shown success with applique DREs and extending the region of laminar flow. This work seeks to extend the DRE technology to include dielectric barrier discharge plasma actuators as well as recreate past experiments with applique DREs. One major need in implementing DREs and controlling crossflow is attaining an accurate measurement of the freestream atmospheric turbulence intensities. Knowing the atmospheric turbulence intensity will allow for comparing wind tunnel experiments to the flight environment and help produce better wind tunnel experiments by allowing them to better match the flight environment. Also, knowledge of the turbulence intensity at the specific instance of an experimental data point will allow for determining if differences in experimental results are the result of a difference in turbulence intensity. It has been determined through this work that the levels of freestream turbulence range from 0.023% - 0.047% with an average of 0.035%. These levels were reached through the use of temporal correlations to remove electronic noise as well as acoustic sound from the hotwire measurements and hence are lower than previously calculated.

Focusing on the city of Atlanta from 1972 to 2012, Halting White Flight explores the neighborhood-based movement to halt white flight from the city’s public schools. While the current historiography traces the origins of modern conservatism to white families’ abandonment of the public schools and the city following court-ordered desegregation, this dissertation presents a different narrative of white flight. As thousands of white families fled the city for the suburbs and private schools, a small, core group of white mothers, who were southerners returning from college or more often migrants to the South, founded three organizations in the late seventies: the Northside Atlanta Parents for Public Schools, the Council of Intown Neighborhoods and Schools, and Atlanta Parents and Public Linked for Education. By linking their commitment to integration and vision of public education to the future economic growth and revitalization of the city’s neighborhoods, these mothers organized campaigns that transformed three generations’ understanding of race and community and developed an entirely new type of community activism.