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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Understanding Design Requirements for Building Reliable, Space-Based FPGA MGT Systems Based on Radiation Test Results

Ellsworth, Kevin M. 20 March 2012 (has links) (PDF)
Space-based computing applications often demand reliable, high-bandwidth communication systems. FPGAs with Mulit-Gigabit Transceivers (MGTs) provide an effective platform for such systems, but it is important that system designers understand the possible susceptibilities MGTs present to the system. Previous work has provided a foundation for understanding the susceptibility of raw FPGA MGTs but has fallen short of testing MGTs as part of a larger system. This work focuses on answering the questions MGT system designers need to know in order to build a reliable space-based MGT system. Two radiation tests were performed with a test architecture built on the Aurora protocol. These tests were specifically designed to discover system susceptibilities, and effective mechanisms for upset detection, recovery, and recovery detection. Test results reveal that the Aurora protocol serves as an effective basis for simple point-to-point communication for space-based systems but that some additional logic is necessary for high reliability. Particularly, additional upset detection and recovery mechanisms are necessary as well as additional status indicators. These additions are minimal, however, and not all are necessary depending on system requirements. The most susceptible part of the MGT system is the MGT tile components on the RX data path. Upsets to these components most often results in data corruption only and do not affect system operation or disrupt the communication link. Most other upsets which do disrupt normal system operation can be recovered automatically by the Aurora protocol with built-in mechanisms. Only 1% of observed events in testing required additional recovery mechanisms not supplied by Aurora. In addition to test data results, this work also provides suggestions for system designers based on various system requirements and a proposed MGT system design based on the Aurora protocol. The proposed system serves as an example to illustrate how test data can be used to guide the system design and determine system availability. With this knowledge designers are able to build reliable MGT systems for a variety of space-based systems.
2

Single Event Mitigation for Aurora Protocol Based MGT FPGA Designs in Space Environments

Harding, Alexander Stanley 17 June 2014 (has links) (PDF)
This work has extended an existing Aurora protocol for high-speed serial I/O between FPGAs to provide greater fault recovery in the presence of high-energy radiation. To improve on the Aurora protocol, additional resets that affect larger portions of the system were used. Detection for additional error modes that occurred but were not detected by the Aurora protocol was designed. Radiation testing was performed on the Aurora protocol with the additional mitigation hardware. The test gathered large amounts of data on the various error modes of the Aurora protocol and how the additional mitigation circuitry affected the system. The test results showed that the addition of the recovery circuitry greatly enhanced the Aurora protocol's ability to recover from errors. The recovery circuit recovered from all but 0.01% of errors that the Aurora protocol could not. The recovery circuit further increased the availability of the transmission link by proactively applying resets at much shorter intervals than used in previous testing. This quick recovery caused the recovery mechanism to fix some errors that may have recovered automatically with enough time. However, the system still showed an increase in performance, and unrecoverable errors were reduced 100x. The estimated unrecoverable error rate of the system is 5.9E-07 in geosynchronous orbit. The bit error rate of the enhanced system was 8.47754E-015, an order of magnitude improvement.
3

Design of an Open-Source Sata Core for Virtex-4 FPGAs

Gorman, Cory 01 January 2013 (has links) (PDF)
Many hard drives manufactured today use the Serial ATA (SATA) protocol to communicate with the host machine, typically a PC. SATA is a much faster and much more robust protocol than its predecessor, ATA (also referred to as Parallel ATA or IDE). Many hardware designs, including those using Field-Programmable Gate Arrays (FPGAs), have a need for a long-term storage solution, and a hard drive would be ideal. One such design is the high-speed Data Acquisition System (DAS) created for the NASA Surface Water and Ocean Topography mission. This system utilizes a Xilinx Virtex-4 FPGA. Although the DAS includes a SATA connector for interfacing with a disk, a SATA core is needed to implement the protocol for disk operations. In this work, an open-source SATA core for Virtex-4 FPGAs has been created. SATA cores for Virtex-5 and Virtex-6 devices were already available, but they are not compatible with the different serial transceivers in the Virtex-4. The core can interface with disks at SATA I or SATA II speeds, and has been shown working at rates up to 180MB/s. It has been successfully integrated into the hardware design of the DAS board so that radar samples can be stored on the disk.
4

L’autobiographie sérielle (« serial autobiography ») dans l’œuvre d’Andrej Belyj / « Serial Autobiography in Andrej Bely’s œuvre »

Levina Parker, Maria 12 November 2013 (has links)
Dans ma thèse, j’analyse la pratique de l’« autobiographie sérielle » et autofiction dans les mémoires et les romans d’Andrej Belyj.Andrej Belyj, qui dans ses mémoires et dans ses romans réécrit de manière constante son enfance et sa vie, peut être considéré comme auteur engagé dans la création d'une «sérielle» autobiographie. Ce processus de réinvention de soi est caractérisé par remodelage et déplacement de son ego et de ses relations avec les parents, avec ses connaissances marquantes et avec ses proches amis, aussi que par les changements des points de vue mystiques, religieux et philosophiques (philosophie néo-kantienne, anthroposophie, etc.). Des identités multiples et des récits sont articulés comme les constituants d'une séquence autobiographique toujours inachevée et qui ne peut jamais aboutir à la conclusion ou à la signification définitive. La construction par Belyj de sa propre identité apparaît sous forme de développement des «variations sur un thème» (Belyj, « Zapiski chudaka »), où chaque nouvelle variation entre en dialogue avec les précédentes en les éliminant partiellement. Les mémoires et les romans de Belyj représentent sa vie comme une série de thèses et antithèses, autrement dit comme une narration dialectique de la vie montante en spirale. / My dissertation examines the practice of serial autobiography and autofiction in Andrej Bely’s prose including his memoirs and novels. Andrej Bely who in his memoirs and fiction constantly rewrites his childhood and life may be said to be engaged in creating serial autobiography. This process is characterized by the reinvention, recreation and relocation of his self and his relationships with his parents, significant others, and close friends.A series of identities and stories are constructed as the constituents of an incomplete, or open, autobiographical sequence which never can reach a conclusion or final signification. Bely’s creation of self-identity presents itself as the development of “variations of a theme” (Bely, Zapiski chudaka) in which every consequent variation engages in a dialogue with and partially cancels the preceding ones. Bely’s memoirs and novels present his life as series of theses and antitheses, in other words as a spirally ascending dialectical life-narrative.

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