Constellation reconfi guration consists of transforming an initial constellation of satellites into some final constellation of satellites to maintain system optimality. Constellations with phased deployment, changing mission requirements, or satellite failures would all benefi t from reconfi guration capability. The constellation reconfiguration problem can be broken into two broad sub-problems: constellation design and constellation transfer. Both are complicated and combinatorial in nature and require new, more efficient methods. Having reviewed existing constellation design frameworks, a new framework, the Elliptical Flower Constellations (EFCs), has been developed that offers improved performance over traditional methods. To assist in rapidly analyzing constellation designs, a new method for orbit propagation based on a sequential solution of Kepler's equation is presented. The constellation transfer problem requires an optimal assignment of satellites in the initial orbit to slots in the final orbit based on optimal orbit transfers between them. A new method for approximately solving the optimal two-impulse orbit transfer with fixed end-points, the so-called minimum Delta v Lambert's problem, is developed that requires the solution of a 4th order polynomial, as opposed to the 6th or higher order polynomials or iterative techniques of existing methods. The recently developed Learning Approach to sampling optimization is applied to the particular problem of general orbit transfer between two generic orbits, with several enhancements specifi c to this problem that improve its performance. The constellation transfer problem is then posed as a Linear Assignment Problem and solved using the auction algorithm once the orbit transfers have been computed. Constellations designed for global navigation satellite systems and for global communications demonstrate signifi cant improvements through the use of the EFC framework over existing methods. An end-to-end example of constellation recon figuration for a constellation with changing regional coverage requirements shows the effectiveness of the constellation transfer methods.

Dissertation (Ph.D.)--University of Toledo, 2009. / Typescript. "Submitted as partial fulfillment of the requirements for the Doctor of Philosophy Degree in Physics." "A thesis entitled"--at head of title. Document is actually a dissertation. Non-Latin script record Bibliography: leaves 236-240.

The thesis seeks to uncover making of architecture as a constellation or cluster of elements which assemble to form spaces humans inhabit. In doing so, it explores the architecture of incompleteness, where fragmented elements combine to form a dialogue with their adjacent elements, intensifying the user's encounter with the structure. Plurality of elements is exposed by increasing their number from single to multiple in varying levels of transparency with the surroundings. The subtraction from a volume to reveal the additive quality of the structure is an effort to amplify the role of structural assembly that elevates the act of visual containment. Agglomeration of members and layers is vital to realize architecture. The programmatic aspect of this thesis manifests itself in a resort town where the proposition of three types of cabin, opposing in character, take shape. The relation of architecture with the ground is primarily observed as resting, floating and sunken. This connection is nourished by exploring the orders, rules and patterns offered by the context. It's an act of revealing and concealing clusters of members in action and assembly. / Master of Architecture / Architecture can be realized using materials and resources that are produced and modified artificially or found naturally. Therefore, its reliance on a physical substance is inevitable. The enormous volume of spaces created by the repetition of components in three dimensions is a result of multiplicity of elements. The thesis establishes itself by revitalizing a resort town called Hot Springs, North Carolina by offering different types of lodging experiences in the cabins. Thirteen unique cubes that are scattered across the site interact with the terrain in three different types of dialogues. The uniqueness of the cubes are conceptualized through contextual anomalies, while the placement of the cubes is guided from the history of the site.

This research describes the development and application of the Disaggregated Integral Systems Concept Optimization Technology (DISCO-Tech) methodology. DISCO-Tech is a modular space system design tool that focuses on the optimization of disaggregated and non-traditional space systems. It uses a variable-length genetic algorithm to simultaneously optimize orbital parameters, payload parameters, and payload distribution for space systems. The solutions produced by the genetic algorithm are evaluated using cost estimation, coverage analysis, and spacecraft sizing modules. A set of validation cases are presented. DISCO-Tech is then applied to three representative space mission design problems. The first problem is the design of a resilient rideshare-manifested fire detection system. This analysis uses a novel framework for evaluating constellation resilience to threats using mixed integer linear programming. A solution is identified where revisit times of under four hours are achievable for $10.5 million, one quarter of the cost of a system manifested using dedicated launches. The second problem applies the same resilience techniques to the design of an expanded GPS monitor station network. Nine additional monitor stations are identified that allow the network to continuously monitor the GPS satellites even when five of the monitor stations are inoperable. The third problem is the design of a formation of satellites for performing sea surface height detection using interferometric synthetic aperture radar techniques. A solution is chosen that meets the performance requirements of an upcoming monolithic system at 70% of the cost of the monolithic system. / Doctor of Philosophy / Civilians, businesses, and the government all rely on space-based resources for their daily operations. For example, the signal provided by GPS satellites is used by drivers, commercial pilots, soldiers, and more. Communications satellites provide phone and internet to users in remote areas. Weather satellites provide short-term forecasting and measure climate change. Because of the importance of these and other space systems, it is necessary that they are designed in an efficient, reliable, and cost-effective manner. The Disaggregated Integral Systems Concept Optimization Technology (DISCO-Tech) is introduced as a means of designing these space systems. DISCO-Tech optimizes various aspects of the space mission, including the number of satellites needed to complete the mission, the location of the satellites, and the sensors that each satellite needs to accomplish its mission. This dissertation describes how DISCO-Tech works, then applies DISCO-Tech to several example missions. The first mission uses satellites to monitor forest fires in California. In order to reduce the cost of this mission, the satellites share launch vehicles with satellites from other, unrelated missions. Next, DISCO-Tech is used to choose the placement of new ground stations for GPS satellites. Because GPS is an important asset, this study also assesses the performance of the network of ground stations when some of the stations are inoperable. Finally, DISCO-Tech is used to design a group of satellites that measure sea level, since sea level is important for climatology research. A design is presented for a group of satellites that perform these measurements at a lower cost than a planned mission that uses a single satellite.

International Telemetering Conference Proceedings / October 18-21, 2004 / Town & Country Resort, San Diego, California / Digital modulation schemes that are power and bandwidth efficient are highly desirable. After non-linear amplification has been done, signal modulation schemes having constant or quasi-constant envelopes are not as susceptible to spectral regrowth as those with non-constant envelopes. Since such distortion generates interference in the adjacent channels, the power operation of the amplifier in non-constant envelope modulations is typically backed off, resulting in systems with reduced power efficiency. On the other hand, constant envelope modulation may have different bandwidth spectra. This paper examines the statistical characteristics of N-GMSK and N-FQPSK [1] signals to assess the bandwidth efficiency in the presence of amplifier nonlinearities.

The collapse of the Spanish real-estate market in 2007-8, and the colossal destruction of jobs it provoked, put an abrupt end to a decade-long model of growth, which was based on the construction and tourism industries as its primary motors as well as on the massive indebtedness of the labouring masses. In the severe economic downturn that ensued, a social conflict appeared: on the one side, the many indebted people forming the movement of the Plataforma de Afectados por la Hipoteca (PAH) and, on the other side, the financial industry. This study offers an ethnographic account of the aforementioned conflict as it unfolds in the precarious reality of Barcelona and Santa Coloma de Gramenet, with a particular emphasis on the experience and struggle of the affected persons. The argument advanced is that the main predicament of the debt conflict is the subordination of life processes to the imperatives of financial accumulation; a situation enabled by a specific constellation of forces, involving the successive governments of Spain, the financial elite, the police, and the courts.

The Houston Constellation is a type of architectural urbanism situated at the intersection of urban revision and projections for cultures yet unknown. The intent is to provide a template for refiguring new lines of sight and interaction within the contemporary city, between contingent forces, institutions, and a public in flux. The Houston Superdistrict: a heterogeneous collection of 20th Century urban paradigms packed loosely underneath a thick canopy. Institutions in medicine, the arts, education, and recreation make it a major hub for local and global populations. The area is undergoing a transformation, yet in contrast to its ambitious visions, current plans project investment that may drop more single objects into this static field. This project proposes an alternative. A constellation of form that slides across cold boundaries and catalyzes a new spatial consciousness to produce a newly legible environment. Encouraging creativity- the very hope for the district in the first place- begins with architectural performance and contextual interaction. Techniques and tactics of planametric alignment, visual continuity, and material cohesion provide the system a relational fitness, while establishing a larger counterform against context’s existing linear boulevards, axes, and grids. Four forms (R,G,B,O) based on site-specific conditions, constitute programmatic points with distinct characters. A complementary duality, the figures in the park (O & B) engage the spatial and airy quality of the city. While the institutional figures (R & G) embed themselves within the local form of their respective campuses. Producing new linkages between fabric and institution: the Museum of Fine Arts Houston and Rice University link through a new space for the arts in the public realm. Hermann Park’s City Beautiful design is reawoken with a new spine and periphery.

This dissertation proposes analytic tools for dynamics and control problems in the perspective of large-scale relative motion without perturbations. Specifically, we develop an exact and efficient analytic solution of satellite relative motion using a direct geometrical approach in spherical coordinates. The resulting solution is then transformed into general parametric equations of cycloids and trochoids. With this transformation, the dissertation presents new findings for design rules and classifications of closed and periodic parametric relative orbits. A new observation from the findings states that the orbit shape resulting from the relative motion dynamics of circular orbit cases in polar views are exactly the same as the parametric curves of cycloids and trochoids. The dynamics problem of satellite relative motion is expanded to include the design of satellite constellations for multiple satellite systems. A Parametric Constellation (PC) is developed to create an identical constellation pattern, or repeating space track, of target satellites with respect to a base satellite. In this PC theory, the number of target satellites is distributed using a real number system for node spacing. While using a base satellite orbit as the rotating reference frame, the PC theory consists of satellite phasing rules and closed form formulae for designing repeating space tracks. The evaluation of the PC theory is illustrated through it’s comparison to the existing Flower Constellation theory in terms of node spacing distribution and constellation design process. For the control problems, the efficient analytic solution is applied to the reference trajectory of satellite relative tracking control systems for inter-satellite links. Two types of relative tracking control systems are developed and each is evaluated to determine which is more appropriate for practical applications of inter-satellite links. All of the proposed analytic solutions and tools in this dissertation will be useful for the mission analysis and design of relative motions involving a two or more satellite system. / Ph. D.

Systems engineering has many subdisciplines which would be useful to study in terms of complex system behavior. However, it is the interactions between a complex system and its operating environment which drive the motivation for this analysis. Specifically, this work introduces a new approach to assessing these interactions called "boundary resilience." While classical resilience theory measures a system's internal reaction to adverse event, boundary resilience evaluates the impacts such an event may have on the surrounding environment. As the scope of this analysis is quite large, it was deemed appropriate to conduct a case study to determine the fundamental tenants of boundary resilience. SpaceX's satellite Internet mega-constellation (StarLink) was chosen due to its large potential to impact the space environment as well as its size and complexity. This study produced two boundary resilience measures, one for local boundary resilience of a single component and one for the global boundary behavior of the entire system. The local metric measures the likelihood of an adverse event occurring at that boundary location as well as its potential to impact the surrounding environment. The global boundary resilience metric reflects a nonlinear relationship among the system components. / Doctor of Philosophy / It is no secret that the world and the systems which enable it to function have become increasingly complex in recent decades. This complexity has the potential to create both innovative uses as well as unplanned and unexpected behaviors in these systems. As they interact with their environment, complex systems can produce equally complex and unpredictable behaviors which have potential to have a negative impact on their environment. This work seeks to study one component of this behavior: resilience. Resilience usually measures a system's ability to continue providing a service in the event of a disruption, or to recover the ability to provide the service after some amount of time. Boundary resilience, on the other hand, takes the perspective of potential environmental damage caused by an adverse event, rather than damage to the system's functionality. This study uses a case study of the StarLink satellite constellation to examine this phenomenon. The outcome of the analysis shows that the size of a complex system negatively impacts its potential to cause damage to the surrounding environment, but increasingly mature components can mitigate this degradation.

In this thesis, the author presents and analyzes two 4-dimensional Constant Envelope Quadrature-Quadrature Phase Shift Keying constellations. Optimal demodulators for the two constellations are presented, and one of them was designed and implemented by the author. In addition, a novel expanded 16-dimensional CEQ2PSK constellation that doubles the number of points without decreasing the distance between points or increasing the peak energy is generated by concatenating the aforementioned constellations with a particular method and restrictions. This original 16-dimensional set of symbols is set-partitioned and used in a multidimensional Trellis-Coded Modulation scheme along with a convolutional encoder of rate 2/3. Effective gain of 2.67 dB over uncoded CEQ2PSK constellation with low complexity is achieved theoretically. A coding gain of 2.4 dB with 8 dB SNR is obtained by using Monte Carlo simulations. The TCM systems and demodulators were tested under an Additive White Gaussian Noise channel by using Matlab's Simulink block diagrams.