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 20 of 44 for “"propagation models"”.
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Propagation models for multiple-antenna systems : methodology, measurements and statistics
… increasingly important that we understand the propagation characteristics of the environments where this new technology will be deployed. In particular the development of low-cost, high-performance system architectures and protocols is largely dependent on the accuracy of available channel …
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Investigating the use of ray tracing for signal-level radar simulation in space monitoring applications: a comparison of radio propagation models
… an open-source, ray-traced radar simulator that models the interactions between spaceborne targets and terrestrial radar systems. This utilises a ray-tracing algorithm to simulate the effects of debris size, shape, orientation, and material properties when computing radar signals in a typical …
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Site-specific propagation prediction for wireless in-building personal communication system design
… describes a geometrical optics model to predict propagation in buildings for personal communication system (PCS) design. Background on the growth of wireless communications is given, and the importance of accurate propagation models is discussed. The peculiarities of propagation in mobile and …
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A Technique for Evaluating the Uncertainties in Path Loss Predictions Caused by Sparsely Sampled Terrain Data
Radio propagation models provide an estimate of the power loss in a communication link caused by the surface of the ground, atmospheric refraction, foliage, and other environmental factors. Many of the models rely on digital topographic databases to provide information about the terrain, and …
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Integration of rain fade into OPNET
… In the wireless modeller module, it uses common propagation models to model radio propagation. It is also possible for users to include their own custom made propagation models to run as part of simulations.This dissertation covers the study done to integrate rain fade into OPNET by including in …
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A low frequency underwater sound propagation model
All wave-theoretic underwater sound propagation models attempt to derive the acoustic field originating from a sound source in a specific environment by either solving the wave equation directly or by solving an approximation there-of. This dissertation describes a normal mode direct solution with …
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Cosmic ray lithium isotope measurement with AMS-01
… are used to provide constraints on cosmic ray propagation models and address the "Lithium Problems".
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Spectrum Efficiency and Security in Dynamic Spectrum Sharing
… of existing methods that use terrain based propagation models for estimating the aggregate interference. First, terrain-based propagation models are computationally intensive and data-hungry making them unsuitable for large real-time spectrum sharing applications such as the spectrum access …
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Mechanistic modelling of single-floor office environments
… In order to deploy systems effectively, propagation models that can reliably and yet efficiently characterise radio propagation behaviour are needed. This thesis describes the philosophy, the logical development, and the performance of a mechanistic modelling approach which is intended …
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Development of a Progressive Failure Model for Notched Woven Composite Laminates
… method for predicting the damage initiation and propagation of woven fabric composites in order to utilize these materials effectively in SLS hardware. This work focuses on notched woven fabric composites under tensile loading. An analytical model consisting of a macro-level failure criterion and …
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Understanding and predicting urban propagation losses
… is a complete understanding of radio wave propagation and the positive and negative effects of spreading and propagation losses. In a communication link, or radio wave transmission, several sources of degradation are mathematically accounted for, to include losses due to materials used, …
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Performance analysis of subaperture processing using a large aperture planar towed array
… these regions is complicated by strong multipath propagation with high transmission loss. Large aperture planar arrays have the potential to improve detection performance due to their high resolution and high gain, but are suceptible to two main performance degradation mechanisms: limited spatial …
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Cross-domain network fault localization
… spectrum. This frame-work not only explicitly models the inference accuracy and privacy requirements for discussing and reasoning over cross-domain problems, but also addresses scalability impacts and facilitates the re-use of existing fault localization algorithms while enforcing domain …
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Indoor Propagation Modeling at 2.4 GHz for IEEE 802.11 Networks
… challenges. It is difficult to predict the propagation of a radio frequency wave in an indoor environment. To assist in deploying the above systems, characterization of the indoor radio propagation channel is essential. The contributions of this work are two-folds. First, in order to build a …
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Bus arrival time prediction using stochastic time series and Markov chains
… tasks. Stochastic time series and delay propagation models to predict bus arrival times using historical information were developed. Markov models were developed to predict propagation of bus delay to downstream bus stops based on heterogeneous conditions. The bus arrival times were …
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Experimental study of software dependability
… as well as hardware faults, can trace fault propagation in software systems and among machines, can monitor whether faults are activated and when the faults are activated, and has accurate time control. The fault models used are extracted from the results of field error data analyses and …
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Detection and localization of aerosol releases from sparse sensor measurements
… is possible. Additionally, while dynamic models can be formulated in many environmental conditions, the underlying model parameters may not be precisely known. The combination of these two issues impacts the effectiveness of inference approaches. We restrict ourselves to propagation models …
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Evaluating Late Pleistocene and Holocene Rupture, Seismic Hazards and Ground Motion in the Lake Tahoe Basin
… ground motions within the basin. eWave propagation models indicate strong, sustained shaking in the basin, threatening several communities. Annual rates of exceedance maps show the higher rates of exceedance of key ground-motion levels strongly correlate with the basin shape. The purpose …
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Analysis of acoustic communication channel characterization data in the surf zone
… by this thesis is concerned with acoustic propagation in shallow water under bubble clouds. The breaking waves injected air deep into the water column. The resulting bubble clouds heavily attenuated acoustic signals, effectively causing total dropouts of the acoustic communication channel. …
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Sound propagation in woodland
A review of past research into sound propagation in woodland is presented. The attenuation of sound in woodland is small between about 800 and 2000Hz and greater at low and high frequencies. Attenuation measurements made in three contrasting woodlands are presented and compared with theoretical …
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