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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

Impact of ion propulsion on performance, design, testing and operation of a geosynchronous spacecraft

Lugtu, Spotrizano Descanzo. January 1990 (has links)
Thesis (M.S. in Astronautical Engineering)--Naval Postgraduate School, June 1990. / Thesis Advisor(s): Agrawal, Brij N. Second Reader: Biblarz, Oscar. "June 2009." Description based on title screen as viewed on 19 October 2009. DTIC Identifier(s): Ion propulsion, synchronous satellites, NSSK (North South Station Keeping). Author(s) subject terms: Ion propulsion, geosynchronous satellite, North-South Station Keeping. Includes bibliographical references (p. 153-156). Also available in print.
2

System engineering of a crosslink for geostationary communications satellites /

Knupp, Greg L. January 1993 (has links)
Report (M.S.)--Virginia Polytechnic Institute and State University. M.S. 1993. / Abstract. Includes bibliographical references (leaves 80-81). Also available via the Internet.
3

Assessment of synchronization in the SDH satellite sector

Van Wyk, Carel Johannes 17 August 2012 (has links)
M.Ing. / The increase of multimedia and broadband communications in recent years has brought about the creation and implementation of synchronousdigital hierarchy (SDH) in the terrestrial network. The implementation of SDH in the satellite sector is a natural extension to improve the current available networks. It will drastically increase the flexibility and usability of the current under-utilized satellite sector. Unfortunately, SDH has still not been implemented in the satellite sector due to certain inherent synchronization problems of SDH and satellites. This thesis investigates some of these synchronization problems. A simulation tool was created that makes an accurate assessment of SDH synchronization in the satellite sector. The tool was used to study SDH links over goestationary (GEO), medium earth orbiting (MEO) and low earth orbiting (LEO) satellites. Various changeable SDH parameters were investigated to determine their influences. Parameters like the bit rate and elastic store length or hysteresis lengths were considered.
4

An attitude and orbit determination and control system for a small geostationary satellite /

Thopil, G. A. January 2006 (has links)
Thesis (MScIng)--University of Stellenbosch, 2006. / Bibliography. Also available via the Internet.
5

Satellite orbit determination using GPS carrier phase in pure kinematic mode /

Byun, Sung Hun, January 1998 (has links)
Thesis (Ph. D.)--University of Texas at Austin, 1998. / Vita. Includes bibliographical references (leaves 226-231). Available also in a digital version from Dissertation Abstracts.
6

On orbital allotments for geostationary satellites /

Gonsalvez, David J. A. January 1986 (has links)
No description available.
7

Routing algorithms and channel reservation strategies for a low earth orbit satellite system. / 近地衛星系統的路由算法和預訂方案 / Jin di wei xing xi tong de lu you suan fa he yu ding fang an

January 1999 (has links)
Tsz-Shing Tam. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1999. / Includes bibliographical references (leaves 84-87). / Abstracts in English and Chinese. / Abstract --- p.i / Acknowledgments --- p.ii / Chapter 1 --- Introduction --- p.1 / Chapter 2 --- Literature Review --- p.6 / Chapter 3 --- System Model --- p.12 / Chapter 3.1 --- Static Architecture --- p.12 / Chapter 3.2 --- Dynamics --- p.15 / Chapter 3.3 --- Communication Paradigm --- p.16 / Chapter 3.4 --- Metric --- p.17 / Chapter 4 --- Routing Algorithms --- p.19 / Chapter 4.1 --- Minimum Hops Algorithm (MHA) --- p.20 / Chapter 4.2 --- Minimum Cost Algorithm (MCA) --- p.21 / Chapter 4.3 --- Mesh Algorithm (MA) --- p.24 / Chapter 4.3.1 --- Construction of the Set of Min-hop Paths --- p.24 / Chapter 4.3.2 --- Choosing a Path in S0 --- p.29 / Chapter 4.4 --- k-mesh Algorithm (KMA) --- p.29 / Chapter 4.4.1 --- Finding Sk --- p.30 / Chapter 4.4.2 --- Choosing a path in Sk --- p.34 / Chapter 4.5 --- Revised Mesh Algorithm (RMA) --- p.34 / Chapter 5 --- Reservation Strategies --- p.36 / Chapter 5.1 --- Introduction --- p.36 / Chapter 5.2 --- Notations --- p.38 / Chapter 5.3 --- Basic Reservation Strategy (BRS) --- p.39 / Chapter 5.4 --- Enhanced Reservation Strategy (ERS) --- p.41 / Chapter 5.5 --- Successor Reservation Strategy (SRS) --- p.43 / Chapter 6 --- Experiment --- p.45 / Chapter 6.1 --- Comparison on Routing Algorithms --- p.47 / Chapter 6.2 --- Comparison on Reservation Strategies --- p.64 / Chapter 7 --- Conclusion --- p.72 / Chapter A --- Existence of paths in Sk --- p.75 / Chapter B --- Estimation of basic reservation strategy guaranteed time --- p.79 / Chapter B.1 --- Basic reservation strategy --- p.79 / Chapter B.2 --- Estimation on Guaranteed Duration --- p.80 / Bibliography --- p.83
8

Outer electron radiation belt dropouts : Geosynchronous and ionospheric responses.

Ogunjobi, Olakunle. January 2011 (has links)
The study of outer radiation belt dynamics has been ongoing for over 5 decades. Outer radiation belt dropouts involve the rapid lost of electron fluxes at the main phase of a storm and subsequent recovery. The characteristics of the dropouts are many and varied. This study examines the Geosynchronous Earth Orbit (GEO) and the ionospheric responses during Stream Interface (SI) andMagnetic Cloud (MC) events, using a combination of ground based and satellite instruments. SI- and MC-driven dropout events were inspected from summary plots of the Synchronous Orbit Particle Analyser (SOPA) instruments from the year 1996 to 2007. Comprehensive studies were done on six selected events. Analysis of the data from the instruments indicate that SIs and MCs are important lost drivers with significant differences in GEO and ionospheric environment. To validate the data and test for consistent response of the events, the Superposed Epoch Analysis (SEA) technique was used. The ground based measurements also revealed how the absorption peaks in the ionosphere correlated with dropouts and geophysical activity. Ionospheric absorption during SI associated dropouts was enhanced for 5 < L < 6, while significant peaks in ionospheric absorption extended to lower L during MC driven dropouts. Wave-particle interactions and southward Interplanetary Magnetic Field (IMF-Bz) are apparent causes for the precipitation. This analysis showed that, within the confines of the selected events, SI driven dropouts were more dominant at the declining phase of the solar cycle while the MC driven dropouts were more dominant during solar maximum. / Thesis (M.Sc.)-University of KwaZulu-Natal, Westville, 2011.
9

[pt] ANÁLISE DE INTERFERÊNCIAS ENVOLVENDO SISTEMAS DE COMUNICAÇÃO QUE UTILIZAM SATÉLITES NÃO-GESTACIONÁRIOS: CASO EM QUE PARCELAS DE INTERFERÊNCIA SÃO MODELADAS POR VARIÁVEIS ALEATÓRIAS / [en] INTERFERENCE ANALYSIS INVOLVING COMMUNICATION SYSTEMS THAT UTILIZE NON-GEOSTATIONARY SATELLITES: MODELING SINGLE-ENTRY INTERFERENCE TERMS RANDOM VARIABLES

RODRIGO ABDALLA FILGUEIRAS DE SOUSA 23 November 2005 (has links)
[pt] O objetivo deste trabalho é estender a aplicação do Método Analítico de avaliação de interferências envolvendo redes de satélites não geoestacionários a situações onde as parcelas de interferência dos diversos satélites de uma dada constelação são modeladas como variáveis aleatórias estatisticamente independentes. A análise deste tipo de situação requer o cálculo de um número muito grande de convoluções. Depois de mostrar que o cálculo direto da convolução é computacionalmente viável e que o uso de simulação de Monte Carlo requer um tempo de computação proibitivo para garantir a precisão necessária, o estudo identifica duas alternativas: utilização indireta do teorema do limite central, e integração numérica utilizando a Regra de Quadratura de Gauss. Por último, o presente trabalho apresenta dois exemplos numéricos de aplicação do Método Analítico, onde é possível observar melhorias na precisão dos resultados obtidos, em relação aos obtidos com outros métodos. / [en] The objective of this work is to extend the use of the Analytical Method for assessing the interference involving non-geostationary satellite networks to situations where the interference entries from the various satellites in a given Constellations are modeled as statistically independent random variables. The analysis of this type of situation requires a large number of convolution computations. After showing that the direct approach to numerically compute convolutions is not feasible and that the use of Monte Carlo simulation techniques require a prohibitive computer time to guarantee the necessary accuracy, the study identifies two alternatives: the indirect use of the Central Limit theorem, and numerical integration using Gauss Quadrature Rules. Finally, the present work presents two numerical example applications of the Analytical Method. The obtained results show an accuracy improvement when compared to those obtained using other methods.
10

A performance analysis of TCP and STP implementations and proposals for new QoS classes for TCP/IP

Holl, David J. January 2003 (has links)
Thesis (M.S.)--Worcester Polytechnic Institute. / Keywords: TCP; RED; satellite; PEP; STP; performance enhancing proxy; segment caching; IP-ABR; Internet; bandwidth reservation; IP-VBR; congestion avoidance; bandwidth sharing. Includes bibliographical references (p. 98-99).

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