Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 18 of 18 for “"artificial satellites"”.
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Reconfigurable satellite constellations for geo-spatially adaptive Earth observation missions
… such as unmanned aerial systems (UAS) or artificial satellites. Space-based architectures can provide non-dominated design solutions on the utility-cost curve compared to alternate architectures through the use of two approaches: (1) reducing satellite manufacturing and launch costs and …
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Design and transformation of three dimensional pupils : diffractive and subwavelength
… imaging system for the detection of artificial satellites. In addition, deformations of volume hologram pupils promise additional opportunities to design further, more sophisticated point spread functions which are potentially useful for many imaging purposes. Deformations using …
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Low-noise frequency synthesis and picosecond timing for satellite laser ranging systems
… for measuring precisely laser runtimes to artificial satellites and to the Moon which are now in successful and permanent operation in five SLR stations around Tokyo, one SLR station in Australia, and one SLR station in Germany. Furthermore, the work has produced three papers and two …
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Time Diversity Modelling and Implementation for Broadcast Satellite Systems at V-band
Deployment of commercial satellite networks at higher frequency bands such as the Ka and V-band has become essential to meet an increasing demand for high data rate multimedia services. Satellite systems operating at high frequency bands offer large bandwidth and are able to provide better quality …
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Viability of High Availability Kband Satellite Communication using Hybrid Fade Mitigation
The C and Ku bands that have been the backbone of satellite telephony and data networks in the past are limited in the amount of bandwidth they provide. Consequently, some broadband Internet services have started to move into the Ka band in order to utilise the bandwidth at these higher …
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Using vibration-based monitoring to detect mass changes in satellites
Vibration-based structural health monitoring could be a useful form of determining the health and safety of space structures. A particular concern is the possibility of a foreign object that attaches itself to a satellite in orbit for adverse reasons. A frequency response analysis was used to …
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A Study of the Effects of Scintillation on Digital Satellite Communication Systems
The growth of satellite communication industry and the need to offer new and better services, to compete with optical fiber systems, have driven the satellite industry to search for higher bandwidth and improved cost of services. Higher frequency bands, such as Ka and V-band, came into play. These …
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Exploring the relationship between the growing number of satellites and space debris in low earth orbit, and people's perception of space debris environmental impacts
… to the numbers of space debris and inactive satellites in Earth's orbits which poses a growing threat of orbital collisions. Orbital collisions can trigger a domino effect, known as the Kessler syndrome, which can cause uncontrolled continuous orbital collisions. This research utilizes …
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Statistical stability of three and more body hierarchical systems in celestial mechanics
… last thirty years, for the purposes of sending artificial satellites and manned craft into space. Yet for 300 years, one of the most important questions posed by celestial mechanics remains unanswered: are the motions of the planets in the Solar System stable? Could planets collide or even …
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Structural assesment of joints in satellites using guided waves
… The test method is intended for responsive satellites designed with prefabricated and pretested panels for which traditional vibration testing would be redundant. A first investigation of the feasibility of using transmitted wave energy for joint quality assessment was conducted at the …
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Radio and satellite tracking and detecting systems for maritime applications
Submitted in fulfillment of the requirements of the Doctor of Technology Degree in Information Technology, Durban University of Technology, Durban, South Africa, 2014.