Formation flying is a new satellite mission concept that is concerned with clusters of satellites in neighboring orbits cooperating to perform a specific task. The tasks may be Earth observation or space-based interferometry where a cluster of small satellites is able to fulfill the same requirements as that of a larger, monolithic satellite. There exist a variety of models for the study of relative motion between two satellites. These include models based upon differential orbital elements, and relative position and velocity coordinates. Extensive work has been done on such models, both in the absence and presence of the J2 perturbation arising from the aspherical nature of the Earth, which causes variations in the orbital elements that describe the orbit. The approximate relative motion can be obtained analytically by using mean elements. However, the true orbit can only be described by the instantaneous osculating elements. An analytical method to propagate the relative motion between two satellites in highly elliptic orbits is the main focus of this thesis. The method is kinematically exact and it maintains a high degree of accuracy even in the presence of J2 perturbations. Mean orbital elements are used for orbit propagation, and expansions involving the powers of eccentricity are not utilized. The true anomaly of the reference satellite is treated as the independent variable, instead of time. The relative orbit kinematics are obtained by using a projection onto a unit sphere. This procedure allows the relative position variables to be treated as angles depending on the orbital element differences. The effect of adding short-period corrections due to J2 to the mean elements is also studied. Finally, the problem of formation reconfiguration is studied. The reconfiguration of a formation may be achieved by using impulsive thrust (velocity increments) or continuous control. This thesis presents a method to obtain the optimal velocity increments through numerical optimization, utilizing the analytical technique developed for relative orbit propagation. A continuous control law is also developed using a candidate Lyapunov function, and the asymptotic stability of the closed-loop system is ascertained.

Thesis (Ph. D.)--University of Washington, 1988. / Vita. Bibliography: leaves [236]-254.

Thesis (M.S.)--West Virginia University, 2008. / Title from document title page. Document formatted into pages; contains ix, 147 p. : ill. (some col.), maps (some col.). Includes abstract. Includes bibliographical references.

A single interval of red chert-clast conglomerate and associated strata (RCC/CRCC interval) occur within the Earp Formation (pennsylvanian-Permian) at many localities in southeastern Arizona, southwestern New Mexico, and northern Mexico, and record a middle Wolfcampian erosional event in the Pedregosa shelf and northern basin. The RCC and CRCC intervals are respective proximal and distal braidplain deposits, in contrast to the Earp Formation exclusive of the RCC/CRCC interval, which consists of interbedded carbonate and fine-grained siliciclastic strata that were deposited in mostly shallow- and marginalmarine environments. Deposition of stream channel, gravel bar, and interfluvial shale beds of the RCC/CRCC interval occurred on a broad, low-lying surface with negligible local topography. Paleocurrents were generally southward. Biostratigraphic evidence suggests that lower Wolfcampian strata below the RCC/CRCC interval were beveled northward. Much of the chert present- in the RCC/CRCC interval is probably residual material from the beveled strata, as well as from a region just north of the Pedregosa shelf. The evolution of the Pedregosa shelf and northern basin during depoSition of the Earp Formation is illuminated by identification of facies belts for three time intervals: (1) restricted shelf, inner shelf, and open-marine shelf facies belts during Virgilian through early Wolfcampian ttme, (2) proximal and distal braidplain facies belts during middle Wolfcampian time, and (3) restricted shelf, estuarine-marginal marine, and tidal-flat facies belts during middle through late(?) Wolfcampian time . The middle Wolfcampian erosional event caxnpanying the deposition of the RCC/CRCC interval was probably related to the Ouachita orogeny. Stratigraphic evidence suggests that the southern Pedregosa basin in Chihuahua, Mexico, evolved rapidly to a deep foreland basin during early or middle Wolfcarrpian tine because of downflexure under northward overthrusts during the Ouachita orogeny. Flexural subsidence of the Pedregosa foreland basin was accanpanied by peripheral forebulging, causing subaerial exposure of large parts of the Pedregosa shelf and northern basin. Deposition of the FCC/CFfX interval probably occurred on the subaerially exposed forebulge. Flexural mxlels predicting the deflection of the lithosphere under isostatic thrust and secliIrent loads agree satisfactorily with the forebulge concept for the origin of the RCC/CRCC interval.

The Upper Cretaceous Cerro Toro Formation, southern Chile, is characterised by thinbedded turbidites that envelope a series of coarse-grained, confined slope complex systems, interpreted as part of the Lago Sofia Member. This deep-water slope system overlies basin floor sheets of the Punta Barrosa Formation, and is overlain by the sand-filled slope channels of the Tres Pasos Formation. Particularly distinctive beds, known as TEDs (transitional event deposits), are up to 40 m thick, laterally extensive, have prominent fluted bases, and have a vertical fabric starting with (1) a thin, inversely-graded, clast-supported base; then (2) a normally-graded and clastsupported interval; (3) an increasingly sand and clay matrix-supported conglomerate, with (4) a progressive upwards increase in matrix and normally grading, both in the floating gravel clast and matrix grain sizes, towards the top; and (5) a co-genetic sandstone on top. In the Cerro Toro formation, these TEDs tend to occur as multiple beds in the initial phases of deposition of each channel complex system. The TEDs are highly aggradational, slightly more amalgamated in the channel-axis, and more layered towards the margins. The fabric of these spectacular event beds is described in some detail from measured sections, combined with petrographic analysis and high-resolution field mapping. The 4 km x 200 m channel systems are contained within topographically irregular bathymetric lows that formed sediment pathways, interpreted to be either the result of slope deformation, or contained by poorly preserved, tectonically disrupted or slumped external levee. Syn-sedimentary tectonism is interpreted to be responsible for sharp changes in the system's architecture from channels to ponds, marked by a sharp change in lithofacies from dominantly conglomerates to dominantly sandstones. A refined architectural analysis is proposed, focusing on the recurrent pattern of at least 5 cycles of conglomerate-filled channel systems – ponded sheet sandstones.

Thesis (M.S.)--West Virginia University, 2002. / Title from document title page. Document formatted into pages; contains ix, 298 p. : ill. (some col.), maps. Includes abstract. Includes bibliographical references (p. 104-113).

Vegetation mapping is often considered the process of identifying landscape patterns of individuals or clusters of species or life forms (LF). At the landscape scale, the larger pattern represented by individuals or clusters represents the conceptualization of "vegetation mapping" and can be used as a building block to describe an ecosystem. To represent these building blocks or LF a "common entity (CE)" concept is introduced to represent the components of Formations as described by the National Vegetation Classification (NVC) system. The NVC has established protocols to consistently represent plant communities and promote coordinated management, particularly across jurisdictional boundaries. However, it is not a universal standard and the methods of producing detailed maps of vegetation CE from very high spatial resolution (VHR) remote sensing data are important research questions.This research addressed how best to understand and represent plant cover in arid regions, the most effective methods of mapping vegetation cover using high spatial resolution data, how to assess the accuracy of these maps, and their value in establishing more standardized mapping protocols across ecosystems. Utilizing VHR products from the IKONOS and QuickBird sensors the study focused on the Coronado National Memorial and Chiricahua National Monument in Arizona and Los Ajos and Pinacate - Grand Desierto Biosphere Reserves in México. Individual CE were semi-automatically mapped incorporating spectral, textural and geostatistical variables. The results were evaluated across sensors, study sites, and input variables. In addition, multiple methods of acquiring field data for accuracy assessment were evaluated and then an evaluation was made of a semi-automatic determination of Formation based on CE.The results of the study suggest consistency across study sites using the IKONOSdata. A comparison between VHR products from the same place is feasible but sensor spectral differences may affect which derived bands would improve classification. CE classification procedures were not significantly different across sensors. The overall accuracy obtained for each Park was 59.5% for Chiricahua using QuickBird and 51.9% using IKONOS; at Pinacate 70.0% using IKONOS, and 55.9% for Ajos. Incorporating the geostatistical semi-variogram variables improved CE accuracy for some CE but not all.

Thesis (Ph. D.)--Virginia Polytechnic Institute and State University, 1994. / Vita. Abstract. Includes bibliographical references (leaves 157-164). Also available via the Internet.

Texte remanié de: Thèse--Sc. nat.--Nice, 1972. / Bibliogr. p. 193-198.

Thesis (M.S.)--Oregon State University, 2004. / Includes maps in pocket. Typescript (photocopy). Includes bibliographical references (leaves 306-314). Also available online.