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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.
291

A Time Correlated Approach to Adaptable Digital Filtering

Grossman, Hy, Pellarin, Steve 10 1900 (has links)
ITC/USA 2006 Conference Proceedings / The Forty-Second Annual International Telemetering Conference and Technical Exhibition / October 23-26, 2006 / Town and Country Resort & Convention Center, San Diego, California / Signal conditioning is a critical element in all data telemetry systems. Data from all sensors must be band limited prior to digitization and transmission to prevent the potentially disastrous effects of aliasing. While the 6th order analog low-pass Butterworth filter has long been the de facto standard for data channel filtering, advances in digital signal processing techniques now provide a potentially better alternative. This paper describes the challenges in developing a flexible approach to adaptable data channel filtering using DSP techniques. Factors such as anti-alias filter requirements, time correlated sampling, decimation and filter delays will be discussed. Also discussed will be the implementation and relative merits and drawbacks of various symmetrical FIR and IIR filters. The discussion will be presented from an intuitive and practical perspective as much as possible.
292

ENCRYPTED CORRELATING SOURCE SELECTOR

Reid, Eric 10 1900 (has links)
ITC/USA 2006 Conference Proceedings / The Forty-Second Annual International Telemetering Conference and Technical Exhibition / October 23-26, 2006 / Town and Country Resort & Convention Center, San Diego, California / Modern telemetry and data streams are often encrypted. The majority of range testing activities require multiple ground stations to collect these streams and send them to a central processing location. Each of these streams currently needs to be individually decrypted before best source selection, processing and analysis. Using innovative techniques, it is possible to time correlate these encrypted streams, compare them with each other and create an output stream of better quality than any of the individual streams. This stream can then be decrypted by a single decryption device, greatly reducing cost and complexity.
293

MULTIPLE TIME BASE SYCHRONIZATION PROCESS APPLIED TO THE FLIGHT TESTS CAMPAIGN OF A GPS ATTITUDE DETERMINATION ALGORITM

Leite, Nelson Paiva Oliveira, Walter, Fernando 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 / For the final evaluation of a GPS attitude determination algorithm, it was determined its true performance in terms of its accuracy, reliability and dynamic response. To accomplish that, a flight test campaign was carried out to validate the attitude determination algorithm. In this phase, the measured aircraft attitude was compared to a reference attitude, to allow the determination of the errors. The system was built using non-dedicated THALES Z-FX airborne GPS receivers and a complete Flight Tests Instrumentation (FTI) System. Each GPS receiver operates synchronized with its internal time base. The FTI measurements are synchronized to an IRIG-B time base. All time bases have their own random walk characteristic. To avoid C/A code ambiguity, when its internal time base approaches ±1ms error from the GPS time, its clock is then corrected causing time and phase observables discontinuities. A multiple time base synchronization process was developed to correlate GPS and FTI data. The results are presented and the residual errors were considered acceptable. These data allowed the determination of the performance and accuracy of the GPS attitude determination algorithm. The tests profiles are fully compliant with the Federal Aviation Administration (FAA) Advisory Circular (AC) 25-7A.
294

Acquiring PN Codes Without Serial Searches Using Modified Correlation Loops

Yadati, Uday, Kosbar, Kurt 10 1900 (has links)
International Telemetering Conference Proceedings / October 26-29, 1998 / Town & Country Resort Hotel and Convention Center, San Diego, California / This paper analyzes the performance of a modified correlation, or delay-locked loop (DLL). These devices typically cross-correlate the received signal with a differentiated version of the originally transmitted signal. This paper describes some interesting properties the loop assumes when the differentiator is replaced by a Hilbert transform. The loop will still track the timing offset of the code, but it will also be able to acquire the signal when the initial offset is greater than one chip time. The new loop may also be superior to traditional DLL in low SNR environments, since it is much less likely to lose lock. Since the new loop is highly non-linear, it is studied through the use of computer simulations.
295

Spatial correlation models for cell populations

Markham, Deborah Claire January 2014 (has links)
Determining the emergent behaviour of a population from the interactions of its individuals is an ongoing challenge in the modelling of biological phenomena. Many classical models assume that the spatial location of each individual is independent of the locations of all other individuals. This mean-field assumption is not always realistic; in biological systems we frequently see clusters of individuals develop from uniform initial conditions. In this thesis, we explore situations in which the mean-field approximation is no longer valid for volume-excluding processes on a regular lattice. We provide methods which take into account the spatial correlations between lattice sites, thus more accurately reflecting the system's behaviour, and discuss methods which can provide information as to the validity of mean-field and other approximations.
296

Random Subspace Analysis on Canonical Correlation of High Dimensional Data

Yamazaki, Ryo January 2016 (has links)
High dimensional, low sample, data have singular sample covariance matrices,rendering them impossible to analyse by regular canonical correlation (CC). Byusing random subspace method (RSM) calculation of canonical correlation be-comes possible, and a Monte Carlo analysis shows resulting maximal CC canreliably distinguish between data with true correlation (above 0.5) and with-out. Statistics gathered from RSMCCA can be used to model true populationcorrelation by beta regression, given certain characteristic of data set. RSM-CCA applied on real biological data however show that the method can besensitive to deviation from normality and high degrees of multi-collinearity.
297

Eye preference in humans and its correlation with eye dominance, visual acuity and handedness

Cederlund, Joakim January 2016 (has links)
Handedness is the most obvious expression of lateralized behaviour in humans. However, there is only limited knowledge about other forms of lateralized behaviour, e.g. preferential use of an eye and whether these may correlate with handedness. Thus to investigate this, 100 subjects (50 males and 50 females) between 11 and 80 years of age were assessed for their eye preference, eye dominance, visual acuity, and handedness. Eye preference was assessed by performing four different monocular tasks, eye dominance by performing the binocular Dolman test, visual acuity was assessed with a Snellen chart and handedness was surveyed using the Edinburgh Handedness Inventory. Regarding eye preference, the right eye was preferred by 69% of the subjects. 90 % of the subjects were consistent for their preferred eye across all four tasks. 66% of the subjects had a dominant right eye, 33% had left eye dominance and 1% could not be assessed using the Dolman test. 56% of the subjects differed in their visual acuity between both eyes, while 43% had the same visual acuity in both of their eyes. 86% of the subjects were right-handed while 4% were left handed and 10% were ambidextrous. Significant correlations were found between visual acuity and eye preference and between visual acuity and eye dominance. The study also found a positive correlation between handedness and eye preference. These results support the notion that there is a weak correlation between the different aspects of lateralized behaviour in humans.
298

Analysis and visualization of collective motion in football : Analysis of youth football using GPS and visualization of professional football

Rosén, Emil January 2015 (has links)
Football is one of the biggest sports in the world. Professional teams track their player's positions using GPS (Global Positioning System). This report is divided into two parts, both focusing on applying collective motion to football. % The goal of the first part was to both see if a set of cheaper GPS units could be used to analyze the collective motion of a youth football team. 15 football players did two experiments and played three versus three football matches against each other while wearing a GPS. The first experiment measured the player's ability to control the ball while the second experiment measured how well they were able to move together as a team. Different measurements were measured from the match and Spearman correlations were calculated between measurements from the experiments and matches. Players which had good ball control also scored more goals in the match and received more passes. However, they also took the middle position in the field which naturally is a position which receives more passes. Players which were correlated during the team experiment were also correlated with team-members in the match. But, this correlation was weak and the experiment should be done again with more players. The GPS did not work well in the team experiment but have potential to work well in experiments done on a normal-sized football field. % The goal of the second part of the report was to visualize collective motion, more specifically leader-follower relations, in football which can be used as a basis for further research. This is done by plotting the player's positions at each time step to a user interface. Between each player, a double pointed arrow is drawn, where each side of the arrow has a separate color and arrow width. The maximum time lag between the between the two players is shown as the "pointiness" of the arrow while the color of the arrow show the maximum time lag correlation. The user can change the metrics the correlations are based of. As a compliment to the lagged correlation, a lag score is defined which tell the user how strong the lagged correlation is.
299

Analysis and optimisation of disc brake calipers

Sergent, Nicolas January 2010 (has links)
Disc brake calipers are subjected to complex mechanical loading and interaction of individual components in a typical brake assembly makes design improvement very challenging. To analyse caliper behaviour, complex Finite Element models were created and successfully validated using a variety of experimental techniques, including exceptionally suitable Digital Image Correlation. A novel methodology to optimise caliper design was developed, using non-linear contact Finite Element Analysis and topology optimisation, to generate lightweight, high performance brake calipers. The method was used on a Formula 1 brake assembly and significant improvement in structural design was achieved, with the new caliper being lighter and stiffer than the original. The same approach was used on more conventional 4 pistons calipers using various boundary conditions with particular focus on mass reduction and considerably lighter designs were achieved. The influence of specific features of the optimised calipers on the structural performance was also successfully investigated.
300

Integrative analysis of high-throughput biological data: shrinkage correlation coefficient and comparative expression analysis

Yao, Jianchao 16 August 2010 (has links)
The focus for this research is to develop and apply statistical methods to analyze and interpret high-throughput biological data. We developed a novel correlation coefficient, shrinkage correlation coefficient (SCC), that fully exploits the similarity between the replicated microarray experimental samples. The methodology considers both the number of replicates and the variance within each experimental group in clustering expression data, and provides a robust statistical estimation of the error of replicated microarray data. Applying SCC-based hierarchical clustering to the replicated microarray data obtained from germinating spores of the fern Ceratopteris richardii, we discovered two clusters of genes with shared expression patterns during spore germination. This computational approach is not only applicable to DNA microarray analysis but is also applicable to proteomics data or any other high-throughput analysis methodology. The suppression of APY1 and APY2 in mutants expressing an inducible RNAi system resulted in plants with a dwarf phenotype and disrupted auxin distribution, and we used these mutants to discover what genes changed expression during growth suppression. We evaluated the gene expression changes of apyrase-suppressed RNAi mutants that had been grown in the light and in the darkness, using the NimbleGen Arabidopsis thaliana 4-Plex microarray, respectively. We compared the two sets of large-scale expression data and identified genes whose expression significantly changed after apyrase suppression in light and darkness, respectively. Our results allowed us to highlight some of the genes likely to play major roles in mediating the growth changes that happen when plants drastically reduce their production of APY1 and APY2, some more associated with growth promotion and others, such as stress-induced genes, more associated with growth inhibition. There is a strong rationale for ranking all these genes as prime candidates for mediating the inhibitory growth effects of suppressing apyrase expression, thus the NimbleGen data will serve as a catalyst and valuable guide to the subsequent physiological and molecular experiments that will be needed to clarify the network of gene expression changes that accompany growth inhibition. / text

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