Engineering Commons^™

A Two-Level Information Modelling Translation Methodology And Framework To Achieve Semantic Interoperability In Constrained Geoobservational Sensor Systems, Paul Stacey

Doctoral

As geographical observational data capture, storage and sharing technologies such as in situ remote monitoring systems and spatial data infrastructures evolve, the vision of a Digital Earth, first articulated by Al Gore in 1998 is getting ever closer. However, there are still many challenges and open research questions. For example, data quality, provenance and heterogeneity remain an issue due to the complexity of geo-spatial data and information representation.

Observational data are often inadequately semantically enriched by geo-observational information systems or spatial data infrastructures and so they often do not fully capture the true meaning of the associated datasets. Furthermore, data …

A Novel Qos-Aware Mpeg-4 Video Delivery Algorithm Over The Lossy Ieee 802.11 Wlans To Improve The Video Quality, Tanmoy Debnath

Doctoral

Video traffic is bursty in nature and has different network requirements compared to other types of traffic (e.g. voice, data) in terms of bandwidth, delay, jitter, and loss etc. So it becomes important to manage video traffic on a WLAN carefully to achieve acceptable levels of Quality of Service (QoS). The unique contribution of this work is that it presents experimental and simulation studies of the performance of real video content streamed over WLAN networks. Under various test scenarios the performance of the WLAN network in terms of delay, loss, throughput etc. is analysed in the presence of background traffic. …

Integration Of Antennas And Solar Cells For Autonomous Communication Systems, Maria Jose Roo Ons

Doctoral

Solar energy is becoming an attractive alternative for powering autonomous communication systems. These devices often involve the use of separate photovoltaics and antennas, which demand a compromise in the utilization of the limited space available. This thesis deals with the design, analysis, fabrication and validation of different techniques for the integration of antennas and solar cells in a single multifunctional device. Four different photovoltaic technologies are considered within this work, namely, polycrystalline silicon (poly-Si), monocrystalline (mono-Si) emitter-wrap-through (EWT) rear contact solar cells, amorphous silicon (a-Si) thin film on glass substrate, and bifacial solar cells. The use of a poly-Si solar …

Analysis Of Mimo Communications Systems Based On Experimentally Observed Channels, Pat Chambers

Doctoral

This thesis presents an analysis of multiple-input/multiple-output (MIMO) communications systems where the objective is to provide a unified solution to the problems of (i) crosstalk coupling in transmission line channels (ii) multi-path fading in the time variant high frequency wireless channel. In the case of transmission line channels, a comparative analysis is presented of the performance of MIMO communications systems based on balanced CAT 5 twisted-pair transmission lines, balanced twisted-pair telephone transmission lines scheme as well as unbalanced flat-pair transmission lines. The unbalanced flat-pair transmission lines are viewed as a model for digital subscriber lines (DSLs) which may be deemed …

Drop Photometer Design., Kevin Tiernan

Doctoral

The tensiograph drop analyser, operating in the mode of ultraviolet-visual absorption photometer, was re-engineered to improve measurement accuracy. As well as instrumentation re-design, the other objective of the research was to analyse tensiograph signals to explore how their features are defined by drop properties. Using fibre optic technology, the tensiograph emits a light beam into a growing pendant drop whereupon it undergoes a number of internal reflections. A portion of the reflected light energy is coupled to a photodiode producing a proportional current that is electronically processed and transferred to a computer for analysis. The signal produced, known as the …