Final Technical Report For The Enhancement Of Autonomous Marine Vehicle Testing In The South Florida Testing Facility Range

The purpose of this grant was to carry out the six scientific experiments on the South Florida Testing Facility (SFTF) Range. In addition to the enhancements to the range, work was performed on all six with some being successfully completed while research continues on the long term tasks

Lasers à blocage de modes à base de boîtes et bâtonnets quantiques pour les peignes de fréquences optiques

Optical frequency combs, generating tens of equally spaced optical carriers from a single laser source, are very attractive for next-generation wavelength division multiplexing (WDM) communication systems. This PhD thesis presents a study on the optical frequency combs generated by mode-locked laser diodes based on low-dimensional semiconductor nanostructures. In this work, the mode-locking performances of single-section Fabry-Pérot lasers based on different material systems are compared on the basis of the optical spectrum width, the timing jitter and pulse generation capabilities. Then, noticing that InAs quantum dashes grown on InP exhibit on average better characteristics than other examined materials, their unique properties in terms of comb stability and pulse chirp are studied in more detail. Laser chirp, in particular, is first investigated by frequency resolved optical gating (FROG) characterizations. Then, chromatic dispersion of the laser material is assessed in order to verify whether it can account for the large chirp values measured by FROG. For that, a high sensitivity optical frequency-domain reflectometry setup is used and its measurement capabilities are extensively studied and validated. Finally, the combs generated by quantum dash mode-locked lasers are successfully employed for high data rate transmissions using direct-detection optical orthogonal frequency division multiplexing. Terabit per second capacities, as well as the low cost of this system architecture, appear to be particularly promising for future datacom applicationsLes peignes de longueurs d'onde, produisant des dizaines de porteuses optiques régulièrement espacées à partir d'une seule source laser, présentent un grand intérêt pour les systèmes de communication à haut débit. Ce travail de thèse porte sur les peignes générés par les diodes laser à blocage de modes basées sur des nanostructures semi-conductrices à basse dimensionnalité. Dans cette étude, les performances en verrouillage de modes de lasers Fabry-Pérot mono-section basés sur différents systèmes de matériaux sont comparées sur la base de la largeur du spectre optique d'émission et de la capacité à produire des impulsions courtes à faible gigue temporelle. En remarquant que les lasers à base de bâtonnets quantiques InAs sur InP présentent de meilleures caractéristiques par rapport aux autres matériaux examinés, leurs propriétés spécifiques en termes de stabilité des peignes de fréquences optiques et de chirp des impulsions sont étudiées plus en détail. Le chirp est d'abord étudié par la technique FROG (frequency-resolved optical gating). Ensuite, la dispersion chromatique du matériau laser est évaluée afin de vérifier si elle peut expliquer les grandes valeurs de chirp mesurées par FROG. Pour cela la technique de réflectométrie optique dans le domaine fréquentiel est utilisée et ses capacités uniques de mesure ont été étudiées et validées. Enfin, ces lasers sont employés avec succès pour les transmissions haut débit à l'aide de la technique de modulation optique OFDM (orthogonal frequency-division multiplexing) en détection directe. Débits de l'ordre du térabit par seconde, ainsi que le faible coût de l’architecture du système, sont très prometteurs pour les data center

Life of a Photon in X-ray Spectroscopy

This thesis summarizes the experimental work in which an ultrafastX-ray laser plasma source was combined with variousscalable direct detection schemes to test a novel approach forlab-based time-resolved X-ray absorption spectroscopy. A laserplasma source based on a water jet target was built and commissioned.X-ray and electron emissions of this source were characterizedwith various direct detection schemes. The proceduresfor spectral retrieval with direct detection CCD’s were optimizedwith regard to the laser plasma source. The novel approach of usinga single photon measuring cryogenic microcalorimeter arrayas a high-resolution (DE/E 2000 @ 6 keV) energy-dispersivedetector was investigated. The potentially very high quantumefficiency, large detection angle and straightforward scalabilitymake this device an interesting photon analyzer for low photonyield experiments. In this thesis a prototype version of this detectorwas built (in cooperation), implemented and commissionedinto the laser plasma setup. With this combination of a lab-basedbroad-band source and the free standing microcalorimeter spectrometerhigh resolution X-ray absorption spectra in transmissionmode were achieved. The thesis presents the first hard X-rayabsorption fine structure (XAFS) spectrum taken with this novelapproach and discusses further improvements and applications

Proceedings of the Second International Mobile Satellite Conference (IMSC 1990)

Presented here are the proceedings of the Second International Mobile Satellite Conference (IMSC), held June 17-20, 1990 in Ottawa, Canada. Topics covered include future mobile satellite communications concepts, aeronautical applications, modulation and coding, propagation and experimental systems, mobile terminal equipment, network architecture and control, regulatory and policy considerations, vehicle antennas, and speech compression

Information Policies and Practices of Knowledge Management(KM) as Related to the Development of the Global Aviation Information Network(GAIN)- An Applied Case Study and Taxonomy Development

The Global Aviation Information Network (GAIN) was initiated in response to U.S. Government policies seeking to reduce airline accidents. GAIN was to disseminate airline or aviation safety information in environments where public disclosure impedes the diffusion of information. Government legislation such as the U.S. Freedom of Information Act and other information policies create risks of public disclosure to those reporting information. Therefore, the problem investigated in this research was to identity and evaluate potential solutions to policy issues in public disclosure that prevent the collection and sharing of aviation safety information. Interactions between GAIN, information policy, and knowledge management (KM) and their impact on the diffusion of information were explored. A generalized taxonomy and ontology of KM was interpreted and presented. This taxonomy represents grounded theory developed from examination of examples and cases of KM contained in the literature. This taxonomy may be used to address challenges related to information or knowledge diffusion in various settings. A specialized taxonomy and ontology addressing issues controlling the diffusion of airline safety information was interpreted. This taxonomy presented issues related to diffusion, disclosure, and policy that may be used to help design and implement airline safety information sharing systems. Content analysis and text-mining processes were used to help interpret and develop the taxonomies, ontologies, and recommendations made in this study. This dissertation presents models for using these techniques to develop taxonomy and related ontology from published documentation and recorded interviews. Practitioners may use the methodology of this study to build taxonomy and ontology in other areas of study. Inductive reasoning was used to develop potential solutions to policy issues in public disclosure that prevent the collection and sharing of aviation safety information within GAIN\u27s community and network of practice. GAIN should evolve into a community of practice serving as an information intermediary to various alliances seeking to share aviation safety information. GAIN should focus on assisting alliances with creating environments of trust, collaboration, and the development of policies and fair processes for addressing public disclosure as a barrier to the diffusion of aviation safety information

Bibliography of Lewis Research Center technical publications announced in 1989

This compilation of abstracts describes and indexes the technical reporting that resulted from the scientific and engineering work performed and managed by the Lewis Research Center in 1989. All the publications were announced in the 1989 issues of STAR (Scientific and Technical Aerospace Reports) and/or IAA (International Aerospace Abstracts). Included are research reports, journal articles, conference presentations, patents and patent applications, and theses

Technology 2000, volume 1

The purpose of the conference was to increase awareness of existing NASA developed technologies that are available for immediate use in the development of new products and processes, and to lay the groundwork for the effective utilization of emerging technologies. There were sessions on the following: Computer technology and software engineering; Human factors engineering and life sciences; Information and data management; Material sciences; Manufacturing and fabrication technology; Power, energy, and control systems; Robotics; Sensors and measurement technology; Artificial intelligence; Environmental technology; Optics and communications; and Superconductivity