Thesis (M.S.)--Brigham Young University. Dept. of Mechanical Engineering, 2006. / Includes bibliographical references (p. 61-63).

Th. Etat--Droit-Histoire du droit--Paris 2, 1973. / Bibliogr. p. 241-245.

Texte remanié de: Ph. D. Th.--Achaeology--University of Newcastle upon Tyne, 1992.

Th.--Lett.--Paris, 1970. / Notice réd. d'après la couv. La page de titre porte par erreur : 1889-1930.

Akademisk avhandling--Kulturhistoria--Göteborg, 1983. / Bibliogr. p. 72-74. Glossaire p. 70-71.

Mobile devices with wireless networking capabilities are used in a wide range of environments. Geolocation information increases the value of the data generated by a device and is vital in the development of a wide range of applications from autonomous vehicles to the Internet of things. Systems that generate signals specifically for geolocation have become widely adopted but, due to fundamental constraints, lack coverage and accuracy in complex urban and indoor environments. In addition to this, the reliance on a single signal source is not desirable in many applications that value the integrity of the geolocation estimate. A direction of research aiming to improve geolocation in indoor and urban environments measures signals of opportunity in order to generate a more robust estimate. While this approach improves signal availability, the unpredictable nature of these variable and uncontrolled signals leads to poor geolocation estimates, which are typically not suitable for use in many applications. This project aims to improve on the accuracy, resilience and integrity of a geolocation estimate obtained from signal of opportunity measurements in indoor and urban environments while reducing hardware requirements. This has been achieved by efficiently coupling signals of opportunity within the radio environment with other system signals, such as those from an inertial measurement unit. Research has been carried out to optimise the coupling of these data sources resulting in techniques to allow the identification and removal of key error drivers from both the radio environment and other system sensors. This thesis proposes a specifically designed extended Kalman filter to improve on the signal coupling. The filter aims to optimise the accuracy of radio environment measurements while also providing the ability to identify signal error sources in urban and indoor environments, leading to both greater accuracy and resilience of the geo-location estimate. Further, the proposed extended Kalman filter may use the radio environment as a source of geolocation data. The ability of the filter to recognise and mitigate leading radio environment error sources such as multipath and interference allowed the design of filters to obtain detailed and accurate signal strength and time of arrival information. The thesis also presents a thorough set of simulation and modelling experiments to investigate and optimise the efficiency of the proposed solutions in a range of environments. Validation testing confirmed that in the urban and indoor environments, the average error of geo-location estimates has been reduced from 10 m to 3 m without improvement to the hardware surrounding infrastructure. The improvements presented in this thesis allow networked devices to improve the value of their data by incorporating the context that comes from increased geolocation accuracy and resilience. In turn, this allows the development of a wide range of new location based applications for mobile devises in indoor and urban environments.

xi, 64 p. : ill. (some col.) / In humans and other mammals the hippocampus is critical for episodic memories, or memories of events that happen in a particular place and at a particular time. When one records from hippocampal pyramidal neurons in awake, behaving rodents, however, the most obvious firing correlate of these neurons is the animal's position within the environment, earning them the name "place cells". Their aggregate activity is thought to provide the animal with a "cognitive map": a map-like neural representation of the external world used to solve spatial problems. Since rats' ability to take shortcuts through novel space was the major evidence leading Edward Tolman to propose the concept of a cognitive map, it follows that place cells should exist for parts of the environment that the animal has not directly-experienced. We therefore compared the relative stability of place cells recorded from rats in observed versus directly explored parts of an environment in response to a pharmacological manipulation that preferentially destabilizes newly-generated place fields. In contrast to the classical cognitive map hypothesis, the formation of stable place fields clearly requires direct experience with a space, suggesting place cells are part of an autobiographical record of events and their spatial context rather than a map-like representation of space automatically calculated from observed environmental geometry. This dissertation includes previously unpublished co-authored material. / Committee in charge: Janis Weeks, Chairperson; Clifford Kentros, Advisor; William Roberts, Member; Terry Takahashi, Member; Edward Vogel, Outside Member

The thesis covers data fusion for aircraft navigation systems in distributed sensor systems. Data fusion methodologies are developed for the design, development, analysis and simulation of multisensor aircraft navigation systems. The problems of sensor failure detection and isolation (FDI), distributed data fusion algorithms and inertial state integrity monitoring in inertial network systems are studied. Various existing integrated navigation systems and Kalman filter architectures are reviewed and a new generalised multisensor data fusion model is presented for the design and development of multisensor navigation systems. Normalised navigation algorithms are described for data fusion filter design of inertial network systems. A normalised measurement model of skewed redundant inertial measurement units (SRIMU) is presented and performance criteria are developed to evaluate optimal configurations of SRIMUs in terms of the measurement accuracy and FDI capability. Novel sensor error compensation filters are designed for the correction of SRIMU measurement errors. Generalised likelihood ratio test (GLRT) methods are improved to detect various failure modes, including short time and sequential moving-window GLRT algorithms. State-identical and state-associated fusion algorithms are developed for two forms of distributed sensor network systems. In particular, innovative inertial network sensing models and inertial network fusion algorithms are developed to provide estimates of inertial vector states and similar node states. Fusion filter-based integrity monitoring algorithms are also presented to detect network sensor failures and to examine the consistency of node state estimates in the inertial network system. The FDI and data fusion algorithms developed in this thesis are tested and their performance is evaluated using a multisensor software simulation system developed during this study programme. The moving-window GLRT algorithms for optimal SRIMU configurations are shown to perform well and are also able to detect jump and drift failures in an inertial network system. It is concluded that the inertial network fusion algorithms could be used in a low-cost inertial network system and are capable of correctly estimating the inertial vector states and the node states.

The orbit of a satellite around the earth is constantly disturbed by various factors, such as variations in the gravitational field and the solar wind pressure. The drift of the satellite position can compromise the mission, and even lead to a crash or a fall in the atmosphere. The station-keeping operations therefore consist in performing an accurate measurement of the satellite trajectory and then in using its thrusters to correct the drift. The conventional solution is to measure the position with the help of a ground based radar. This solution is expensive and does not allow to have the satellite position permanently: the trajectory corrections are therefore infrequent. A positioning and autonomous navigation system using constellations of navigation satellites, called Global Navigation Satellite System (GNSS), allows a significant reduction in design and operational maintenance costs. Several studies have been conducted in this direction and the first navigation systems based on GPS receivers, are emerging. A receiver capable of processing multiple navigation systems, such as GPS and Galileo, would provide a better service availability. Indeed, Galileo is designed to be compatible with GPS, both in terms of signals and navigation data. Continuous knowledge of the position would then allow a closed loop control of the station keeping. Initially, we defined what the specifications of a multi-mission space receiver are. Indeed, the constraints on such a receiver are different from those for a receiver located on the surface of the Earth. The analysis of these constraints, and the performance required of a positioning system, is necessary to determine the specifications of the future receiver. There are few studies on the subject. Some of them are classified; others have, in our view, an analytical bias that distorts the determination of specifications. So we modeled the system: GNSS and receivers satellite orbits, radio frequency link. Some parameters of this link are not given in the specification or manufacturers documents. Moreover, the available theoretical data are not always relevant for realistic modeling. So we had to assess those parameters using the available data. The model was then used to simulate various scenarios representing future missions. After defining analysis criteria, specifications were determined from the simulation results. Calculating a position of a satellite navigation system involves three main phases. For each phase, there are several possible algorithms, with different performance characteristics, the circuit size or the computation load. The development of new applications based on navigation also drives the development of new adapted algorithms. We present the principle for determining a position, as well as GPS and Galileo navigation signals. From the signal structure, we explain the phases of the demodulation and localization. Through the use of GPS and Galileo constellations, standard algorithms achieve the performance required for space applications. However, these algorithms need to be adapted, thus some parts were specifically designed. In order to validate the choice of algorithms and parameters, we have simulated the various operating phases of the receiver using real GPS signals. Finally, impact and prospects are discussed in the conclusion.

Orientador: Arlete de Jesus Brito / Banca: Fumikazu Saito / Banca: Rosa Lúcia Sverzut Baroni / Resumo: Este estudo tem como principal objetivo apresentar uma interpretação histórica acerca do conceito de linhas de rumo (loxodromia), que consiste em uma curva utilizada na navegação, cuja característica é interceptar todos os meridianos da esfera terrestre segundo um ângulo constante. Para isto, utilizamos as obras do matemático português, Pedro Nunes, que foi o primeiro de que temos conhecimento a tratar sobre este conceito. A metodologia adotada para a realização deste objetivo foi a de interpretação, proposta por John B. Thompson, que reforça a importância de se analisar os contextos, assim como a análise formal do objeto a ser estudado, denominado por ele por forma simbólica. Assim, apresentamos inicialmente um contexto histórico dos séculos XV e XVI em Portugal, que tem como temática o Renascimento e outras características como as grandes navegações e descobrimentos, a imprensa, o desenvolvimento do comércio, da cartografia e da matemática. Além disso, também apresentamos uma análise das obras de Pedro Nunes que contém estudos sobre a linha de rumo e sua distinção de outra curva denominada ortodromia, que consiste em um círculo máximo na esfera / Abstract: This study primary aim is to present a historic interpretation of the concept of rhumb line (loxodrome), a curved line used to navigate. It intersects the meridians of the Earth's sphere at the same angle. We use the works of a portuguese mathematician Pedro Nunes, the first one we know to discuss about this concept. The methodology adopted to accomplish this aim was the interpretation proposed by John B. Thompson, which reinforces the importance of analyzing the context, such as the formal analyze of the studied object, named in a symbolic way. Initially we present a historical context of the XV and XVI centuries in Portugal, that has Renaissance and others characteristics as the great navigations and discoveries, the press, the development of the commerce, the cartography and math as a theme. Moreover, we present an analyze of the works of Pedro Nunes that contain studies about the rhumb line and its difference comparing to another curve named orthodromic, a great circle in the sphere / Mestre