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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

Copula models with Weibull distributions : application in fading channels.

Tseng, Tzu-chiang 23 July 2009 (has links)
In this work, copula models for fitting bivariate response data with Weibull marginal distributions are studied, which are motivated by the need of model fading channels in signal applications. The analytical expressions for the joint probability density function (p.d.f.), and joint cumulative distribution function (c.d.f.) are utilized as the bivariate distribution of the fading channels data with not necessarily identical fading parameters and average powers. The performances of outage probability employing diversity receivers, called as selection combining (SC), equal-gain combining (EGC), and maximal-ratio combining (MRC) of two diversity receivers under bivariate copula models with Weibull marginal distributions are presented. They are also compared with the results in Sagias (2005) where the data assumed to follow the bivariate Weibull distribution. It will be demonstrated that the copula models can approximate the bivariate Weibull distribution used in Sagias (2005) very closely with suitable copula model, and the computations for obtaining the performances of outage probability under SC are much simplified. Keywords and phrases: equal-gain combining, maximal-ratio combining, selection combining
2

An Examination of Spatial Diversity Combining Using Commercial Off the Shelf Equipment in Missile Telemetry

Graham, Richard A., Jr. 10 1900 (has links)
ITC/USA 2014 Conference Proceedings / The Fiftieth Annual International Telemetering Conference and Technical Exhibition / October 20-23, 2014 / Town and Country Resort & Convention Center, San Diego, CA / This experiment has two purposes. One, to determine if a modern diversity combiner normally used in missile telemetry for polarization diversity can be used for spatial diversity to obtain a gain in the signal quality. Two, to determine if a simple test can be designed such that a non-laboratory test can be performed by the average telemetry operator in order to assess the first purpose.
3

A FRAMEWORK FOR THE META-ANALYSIS OF SURVEY DATA

FOX, KARLA MICHELLE PHILLIPS COOPER 06 December 2011 (has links)
The research outlined in this thesis covers various different statistical issues relating to meta-analysis of survey data. These issues include the creation of an original comprehensive methodological framework for combining survey data, a comparison of this framework with the traditional one proposed by Cochran for the combination of experiments, a proposal for a new weighting method that takes into account the differences in variability due to the sampling plan, an examination of the convergence of meta-analytic estimators, and a discussion on the numerous implicit assumptions researchers make when they are using meta-analysis methods with survey data along with guidelines for completing and reporting reviews when the data come from surveys. / Thesis (Ph.D, Mathematics & Statistics) -- Queen's University, 2011-12-06 15:11:24.717
4

Performance Analysis of Minimum Selection GSC with Channel Estimation Errors in Rayleigh Fading Channels

Zhu, Chao January 2007 (has links)
No description available.
5

TELEMETRY LINK RELIABILITY IMPROVEMENT VIA “NO-HIT” DIVERSITY BRANCH SELECTION

Jefferis, Robert P. 10 1900 (has links)
International Telemetering Conference Proceedings / October 18-21, 2004 / Town & Country Resort, San Diego, California / Multipath propagation consisting largely of specular reflection components is known to be the major channel impairment in many aeronautical mobile telemetry (AMT) applications. Adaptive equalizers are not effective against flat fading commonly created by strong power delay profile components representing small fractions of the transmitted symbol period. Avoidance and diversity techniques are the only practical means of combating this problem. A new post-detection, no-hit diversity branch selector is described in this paper. Laboratory and limited flight test data comparing non-diversity, selection diversity and intermediate frequency (IF) combining techniques are presented.
6

Quantifying Coding Gain from Telemetry Data Combining

Forman, Michael A., Condreva, Ken, Kirchner, Gary, Lam, Kevin 10 1900 (has links)
ITC/USA 2008 Conference Proceedings / The Forty-Fourth Annual International Telemetering Conference and Technical Exhibition / October 27-30, 2008 / Town and Country Resort & Convention Center, San Diego, California / A method for combining telemetry data and quantifying the resulting coding gain for a ballistic missile test flight is presented. Data received from five ground stations in 54 data files with 18 million intermittent frames is combined, to create a single file with 1.5 million continuous frames. Coding gain provided by data combining is as high as 30 dB, with a useful improvement of 5 dB at boost and terminal stages. With frame reconstruction techniques, erroneous words in a frame are reduced from 2.1% to 0.12 %.
7

DIVERSITY BRANCH SELECTION IN REAL WORLD APPLICATION

Formeister, Richard 10 1900 (has links)
ITC/USA 2007 Conference Proceedings / The Forty-Third Annual International Telemetering Conference and Technical Exhibition / October 22-25, 2007 / Riviera Hotel & Convention Center, Las Vegas, Nevada / Multipath propagation continues to be the dominant channel impairment in many aeronautical mobile telemetry (AMT) applications. Avoidance and diversity techniques continue to be the only practical means to combat this problem. In 2004 limited results from the development of a new post-detection, no-hit diversity selector were reported. Late breaking results from flight test were reported orally. A review of the methodology, flight test results and conclusions are presented in this paper. Also presented is an update describing enhancements of the implementation which emphasize operational flexibility as well as support for alternate demodulator products.
8

Nonparametric Combination Methodology : A Better Way to Handle Composite Endpoints?

Baurne, Yvette January 2015 (has links)
Composite endpoints are widely used in clinical trials. The outcome of a clinical trial can affect many individuals and it is therefore of importance that the methods used are as effective and correct as possible. Improvements of the standard method of testing composite endpoints have been proposed and in this thesis, the alternative method using nonparametric combination methodology is compared to the standard method. Performing a simulation study, the power of three combining functions (Fisher, Tippett and the Logistic) are compared to the power of the standard method. The performances of the four methods are evaluated for different compositions of treatment effects, as well as for independent and dependent components. The results show that using the nonparametric combination methodology leads to higher power in both dependent and independent cases. The combining functions are suitable for different compositions of treatment effects, the Fisher combining function being the most versatile. The thesis is written with support from Statisticon AB.
9

A Study on Diversity Combining for Fast Frequency Hopping Systems

Dai, Cyuan-Li 28 November 2007 (has links)
In frequency-hopping (FH) system, the signal is not only impaired by receiver thermal noise, but also impaired by jamming, interference or multipath fading. Therefore, diversity techniques are used to reduce these impairments. Two systems are considered in this thesis, the first one is fast frequency-hopping/M-ary frequency-shift-keying (FFH/MFSK) System and the second one is fast frequency-hopping multiple access/M-ary frequency-shift-keying system (FFHMA/MFSK) System. In the first system, we consider three cases, multitone jamming (MTJ), broad-band noise jamming (BBN) and partial-band noise jamming (PBN).In the second system, we consider multiuser cases with multiple access interference, frequency-selective fading, and AWGN channels. In this thesis, two modified diversity combining methods are proposed. These methods are modified product and Order Statistics-Normalized Envelope Detection (OSNED) methods by adding the reliable order statistics. From simulation results, these methods can effectively combat multitone jamming and partial-band noise jamming. When comparing with product and OSNED in multiple access interference channel and frequency-selective fading channels, the proposed methods have better performance at high SNR. The proposed methods also do not need the additional side information as hard limiting majority vote (HLMV) and soft limiting combiner (SLC) needed.
10

Origin and functioning of circumstantial clause linkers : a cross-linguistic study

Martowicz, Anna January 2011 (has links)
The thesis analyses a variety of clause linkers used in the world’s languages as dedicated markers of four circumstantial relations between states of affairs: anteriority (‘after’), causality (‘because’), purpose (‘in order to’) and conditionality (‘if’). Focusing primarily on the function of the linkers rather than on their formal properties the study scrutinizes the origin and functioning of free-word adverbial subordinators, converbal endings as well as other subordinating affixes and polymorphemic structures specialized for clause-linking functions. The database consist of nearly 700 items which come from a geographically and genetically balanced sample of 84 languages. In the first part of the thesis I discuss in detail the scope of the study, theoretical foundations (functional approach to language analysis) and methodology. In the second part I focus on the issues of grammaticalization and semantic scope of the linkers. The analysis of patterns of polysemy of the linkers, as well as the make-up of the polymorphemic items among them provide material for the reconstruction of the most common sources and pathways of grammaticalization. Looking closer at the patterns of semantic polyfunctionality (i.e. other circumstantial meanings that the clause linkers convey in addition to being markers of the four analysed relations) I reveal the architecture of the network of their cognitive affinities. The result of this investigation is a set of findings, which add to our understanding of the origin and functioning of the markers – a topic which has received little attention so far. The third part of the dissertation is dedicated to the analysis of the crosslinguistic variation in the degree of grammaticalization, lexicalization and explicitness of the linkers and discussion on the motivations behind their development. The main body of the analyses is focused on the investigation of the potential influence of a variety of socio-cultural factors on the variations observed. The factors include those most often mentioned in the context of the forces shaping language structure: presence and vitality of written form as well as other media of displaced communication, presence of the language in schooling, population size of the speech community, and type of society. The results obtained show that the degrees of grammaticalization, lexicalization and explicitness are much stronger correlated with socio-cultural factors for anteriority and conditionality than for causality and purpose. In order to account for the differences I evoke the concepts of cognitive salience and communicative pressure arguing that the influence of socio-cultural factors on language structure should always be considered in a broader context which includes also pragmatics and cognitive psychology.

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