Dissertations / Theses on the topic 'Spatial correlation'
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Sweet, Dustin L. "Forecasting unemployment with spatial correlation." Diss., Columbia, Mo. : University of Missouri-Columbia, 2005. http://hdl.handle.net/10355/4250.
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Thesis (M.S.)--University of Missouri-Columbia, 2005.The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file viewed on (July 11, 2006) Includes bibliographical references.
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Markham, Deborah Claire. "Spatial correlation models for cell populations." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:db5e3d9c-1871-4da1-9e20-c7e04b8256ae.
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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 In this thesis, we explore situations in which the mean-field approximation is no longer valid for volume-excluding processes on a regular lattice.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.
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Heddle, Steven B. "Optical correlation using pixellated spatial light modulators." Thesis, University of Edinburgh, 1993. http://hdl.handle.net/1842/14043.
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Optical correlation by filtering in the Fourier plane of an optical processor has recently received much attention, due to the advent of rapidly reconfigurable Fourier plane filters - spatial light modulators (SLMs). Many algorithms have been developed to generate filters, mostly binary in nature in line with the capabilities of current SLMs. This thesis reviews optical correlation techniques and SLM technology, before turning attention to the consequences of the pixellated structure of the Fourier plane filters generally necessary to enable arbitrary filter patterns to be written to an SLM. Conventionally the pixels are identical and regularly spaced on a rectangular grid. This is shown to lead to replication in the output plane of the correlator, and aliasing if the input exceeds dimensions related to the pixel spacing in the Fourier plane flter. If the input is also provided by an SLM, this requires the number of pixels across the filter SLM (its space-bandwidth product) to be greater than or equal to that of the input, even though the target itself may occupy only a small area of the total input scene, in order to prevent aliasing and misleading correlation results. If the replication and aliasing could be prevented, the space bandwidth product of the filter need only be matched to that of the target to be detected, rather than the entire input scene. The replicas arise through convolution with distinct spectral orders in the SLM's Fourier spectrum. A means of eliminating the spectral orders other than the zero order through randomisation of the pixel positions is presented and analysed, and implemented on transmissive matrix addressed SLMs custom designed and built for the work of this thesis.
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Öster, Jonas. "Spatial correlation between lightning strikes and whistler observations." Thesis, KTH, Rymd- och plasmafysik, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-91828.
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A whistler wave is a Very Low frequency (VLF) trace that obtains its characteristics from dispersive propagation in the magnetosphere. Field-aligned ducts of enhanced plasma density ensure the propagation from one hemisphere to the other. The origin of these signals is lightning strikes that emit radiation which spans the entire spectrum with the bulk being in the VLF band. The VLF portion can travel great distances within the Earth-ionosphere waveguide (EIWG) before penetrating through the ionosphere, and exciting a duct. The relative location, compared to the duct, of those strikes that cause whistlers is unknown. It is of interest to examine where the whistlers that have been observed at Tihany, Hungary, and Dunedin, Nerv Zealand, originate. This is one tool to gain further understanding of the properties, especially the plasma density structure, of the ionosphere and the magnetosphere. Therefore time series with observed whistlers from these stations has been correlated with lightning data obtained from the World Wide Lightning Location Network (WWLLN). The results show that whistlers observed at Tihany mainly originate from lightning in an area surrounding the magnetic conjugate point which is situated in the ocean just off East London, South Africa. This area, called the source region, has a radius slightly less than 1000 km. Whistlers also originate from lightning activity over the rest of Southern Africa and the northern parts of South America. A clear diurnal distinction is seen in that the correlation is maximized when the whistler station and the source region are covered in darkness. This is believed to relate to the diurnal variation of the ionospheric profile, which becomes more transparent to VLF waves at night. A similar diurnal correlation pattern for Dunedin was also obtained. The general correlation results for Dunedin were very sporadic. Whistler statistics for the two stations and lightning statistics for the Tihany's magnetic conjugate point are also presented. It reveals a general diurnal maximum in received whistlers in dark hours for Tihany with absolute maximum at 1 UTC and for Dunedin, the maximum occurs in the afternoon with absolute maximum at 15 UTC. It also reveals a seasonal maximum when the conjugate point is in the summer season. The lightning statistics for Tihany's magnetic conjugate point reveals a diurnal maximurn ranging from the afternoon until a couple of hour after midnight. Something worth noting is the delay between the peaks of lightning activity and whistler registration at Tihany. The lightning activity peaks around 18 UTC. The explanation is once again believed to relate to the behavior of the ionosphere in darkness.
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Liu, Xiaoli. "Spatial Correlation Study on Hybrid Electric Vehicle Adoption." The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1397646595.
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Fawcett, Philip Andrew. "An investigation on planar velocimetry by spatial cross correlation." Diss., Georgia Institute of Technology, 1992. http://hdl.handle.net/1853/15731.
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Bouchal, Petr. "Correlation and Spiral Microscopy using a Spatial Light Modulation." Doctoral thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2016. http://www.nusl.cz/ntk/nusl-255286.
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Dizertační práce je uceleným shrnutím výsledků dosažených v průběhu doktorského studia. V úvodní části práce je představena motivace, odborné a technické zázemí a grantová podpora realizovaného výzkumu. Popsány jsou také dosažené výsledky a jejich význam pro skupinu Experimentální biofotoniky, Ústavu fyzikálního inženýrství, Vysokého učení technického v Brně. Vědecká část práce je rozdělena do dvou hlavních bloků, které se postupně zabývají návrhem nových zobrazovacích koncepcí a technickou modifikací stávajících zobrazovacích systému v praktických aplikacích. Dosažené vědecké výsledky podporují vývoj v oblastech korelační a spirální mikroskopie s prostorovou modulací světla. V části zabývající se návrhem nových zobrazovacích koncepcí je provedena studie korelačního zobrazení v podmínkách proměnné časové a prostorové koherence. Následně jsou zkoumány možnosti praktického využití vírových a nedifrakčních svazků v oblastech korelační, holografické a optické mikroskopie. Interference vírových svazků a samozobrazení nedifrakčních svazků je postupně využito k dosažení 3D zobrazení s hranovým kontrastem a rotující bodovou rozptylovou funkcí. Pokročilé zobrazovací metody jsou úspěšně zavedeny optickou cestou ale i digitální modifikací holografických záznamů. Výsledky teoretických modelů a numerických simulací jsou doprovázeny praktickým vyhodnocením navržených zobrazovacích principů. V technicky zaměřené části jsou navrženy nové způsoby zavedení prostorové modulace světla, které umožňují rozšíření zorného pole v experimentech korelačního zobrazení a dosažení achromatizace při zobrazení pomocí programovatelných difraktivních prvků. Rozšíření zorného pole v korelačních experimentech umožňuje přizpůsobovací optický systém vložený do standardní zobrazovací sestavy. Achromatizace difraktivního zobrazení je zajištěna použitím speciálně navrženého refraktivního korektoru. V navazující části je navržena nová metoda krokování fáze, která pracuje s dvojlomností kapalných krystalů využívaných v systémech pro prostorovou modulaci světla. Použití metody je experimentálně demonstrováno v polarizačně modifikovaném Mirau interferometru. Získané technické zkušenosti jsou využity v praktickém návrhu a realizaci multimodálního zobrazovacího systému s prostorovou modulací světla.
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Alem, Yibeltal Fantahun. "Sparse recovery on sphere and modelling 3d spatial correlation." Phd thesis, Canberra, ACT : The Australian National University, 2015. http://hdl.handle.net/1885/150051.
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Merve, Akis. "Temporal and Spatial Interference Correlations in Cognitive Radio Networks with Vertical Cooperation." Thesis, KTH, Kommunikationsnät, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-91892.
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Cognitive radio technology provides a solution for the spectrum scarcity issue by allowing the unlicensed users which are the cognitive radio devices to share the licensed band with the licensed (primary) users. The abilities of cognitive radio device help the secondary (unlicensed) nodes to observe the licensed band and to adjust their transmission parameters for maintaining the primary communication since in cognitive radio networks, it is essential that the existence of the unlicensed users must not harm the licensed network. Under these circumstances, we consider vertical cooperative transmission where primary transmission is not severely damaged by the secondary interference since each primary pair (transmitter and receiver) selects a neighbor secondary user as a cooperative relay to assist their transmission. Cooperation provides an increase in the signal-tointerference-ratio (SIR) of the primary network which can be harnessed by the secondary network as an additional bandwidth for their communication. We propose three relay selection rules so the influence of the relay’s position over the temporal and spatial correlations can be evaluated for different network conditions. Additionally, we implement primary exclusive region (PER) for each primary pair in the network which covers primary nodes, and all secondary users locate inside the zone become inactive. According to the outage model proposed in paper [2], temporal and spatial correlations are assumed to be 1 and 0 respectively; however it is estimated that regarding the environmental factors and the relay’s location, these correlation values may vary. This thesis work is based on the validation of the assumptions provided in paper [2] and our results demonstrate that the temporal and spatial correlation values changes under different circumstances and with different relay selection rules. The simulation results also show that PER significantly stimulates the cooperation performance thereby increases the transmission quality of the primary network.
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Wang, Zhao Qi. "Real-time optical intensity correlation using photorefractive BSO." Thesis, Abertay University, 1995. https://rke.abertay.ac.uk/en/studentTheses/f1330975-bc23-4532-ac7b-8aeb9cad8c81.
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Real-time optical intensity correlation using a photorefractive BSO crystal and a liquid crystal television is implemented. The underlying physics basis is considered, some specific techniques to improve the operation are proposed, and several optical pattern recognition tasks are achieved. Photorefractive BSO is used as the holographic recording medium in the real-time intensity correlator. To improve the dynamic holographic recording, a moving grating technique is adopted. The nonlinear effects of moving gratings at large fringe modulation are experimentally investigated, and are compared with numerical predictions. Optical bias is adopted to overcome the difficulty of a large drop in the optimum fringe velocity with moving gratings. The effects of optical bias on the optimum fringe velocity and on the diffraction efficiency are studied. To overcome the inherent drawback of low discrimination of intensity correlation in optical pattern recognition, real-time edge-enhanced intensity correlation is achieved by means of nonlinear holographic recording in BSO. Real-time colour object recognition is achieved by using a commercially available and inexpensive colour liquid crystal television in the intensity correlator. Multi-class object recognition is achieved with a synthetic discriminant function filter displayed by the Epson liquid crystal display in the real-time intensity correlator. The phase and intensity modulation properties of the Epson liquid crystal display are studied. A further research topic which uses the Epson liquid crystal display to realize a newly designed spatial filter, the quantized amplitude-compensated matched filter, is proposed. The performance merits of the filter are investigated by means of computer simulations.
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Cepel, Raina. "The spatial cross-correlation coefficient as an ultrasonic detection statistic." Diss., Columbia, Mo. : University of Missouri-Columbia, 2007. http://hdl.handle.net/10355/5054.
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Thesis (M.S.)--University of Missouri-Columbia, 2007.The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on April 7, 2008) Includes bibliographical references.
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Shen, Lingli. "Spatial mass spectral data analysis using factor and correlation models." Thesis, University of Sheffield, 2015. http://etheses.whiterose.ac.uk/9506/.
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ToF-SIMS is a powerful and information rich tool with high resolution and sensitivity compared to conventional mass spectrometers. Recently, its application has been extended to metabolic profiling analysis. However, there are only a few algorithms currently available to handle such output data from metabolite samples. Therefore some novel and innovative algorithms are undoubtedly in need to provide new insights into the application of ToF-SIMS for metabolic profiling analysis. In this thesis, we develop novel multivariate analysis techniques that can be used in processing ToF-SIMS data extracted from metabolite samples. Firstly, several traditional multivariate analysis methodologies that have previously been suggested for ToF-SIMS data analysis are discussed, including Clustering, Principal Components Analysis (PCA), Maximum Autocorrelation Factor (MAF), and Multivariate Curve Resolution (MCR). In particular, PCA is selected as an example to show the performance of traditional multivariate analysis techniques in dealing with large ToF-SIMS data extracted from metabolite samples. In order to provide more realistic and meaningful interpretation of the results, Non-negative Matrix Factorisation (NMF) is presented. This algorithm is combined with the Bayesian Framework to improve the reliability of the results and the convergence of the algorithm. However, the iterative process involved leads to considerable computational complexity in the estimation procedure. Another novel algorithm is also proposed which is an optimised MCR algorithm within alternating non-negativity constrained least squares (ANLS) framework. It provides a more simple approximation procedure by implementing a dimensionality reduction based on a basis function decomposition approach. The novel and main feature of the proposed algorithm is that it incorporates a spatially continuous representation of ToF-SIMS data which decouples the computational complexity of the estimation procedure from the image resolution. The proposed algorithm can be used as an efficient tool in processing ToF-SIMS data obtained from metabolite samples.
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Sabade, Sagar Suresh. "Integrated circuit outlier identification by multiple parameter correlation." Diss., Texas A&M University, 2004. http://hdl.handle.net/1969.1/267.
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Semiconductor manufacturers must ensure that chips conform to their specifications before they are shipped to customers. This is achieved by testing various parameters of a chip to determine whether it is defective or not. Separating defective chips from fault-free ones is relatively straightforward for functional or other Boolean tests that produce a go/no-go type of result. However, making this distinction is extremely challenging for parametric tests. Owing to continuous distributions of parameters, any pass/fail threshold results in yield loss and/or test escapes. The continuous advances in process technology, increased process variations and inaccurate fault models all make this even worse. The pass/fail thresholds for such tests are usually set using prior experience or by a combination of visual inspection and engineering judgment. Many chips have parameters that exceed certain thresholds but pass Boolean tests. Owing to the imperfect nature of tests, to determine whether these chips (called "outliers") are indeed defective is nontrivial. To avoid wasted investment in packaging or further testing it is important to screen defective chips early in a test flow. Moreover, if seemingly strange behavior of outlier chips can be explained with the help of certain process parameters or by correlating additional test data, such chips can be retained in the test flow before they are proved to be fatally flawed. In this research, we investigate several methods to identify true outliers (defective chips, or chips that lead to functional failure) from apparent outliers (seemingly defective, but fault-free chips). The outlier identification methods in this research primarily rely on wafer-level spatial correlation, but also use additional test parameters. These methods are evaluated and validated using industrial test data. The potential of these methods to reduce burn-in is discussed.
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Wang, Xuesong. "SAFETY ANALYSES AT SIGNALIZED INTERSECTIONS CONSIDERING SPATIAL, TEMPORAL AND SITE CORRELATION." Doctoral diss., University of Central Florida, 2006. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3436.
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Statistics show that signalized intersections are among the most dangerous locations of a roadway network. Different approaches including crash frequency and severity models have been used to establish the relationship between crash occurrence and intersection characteristics. In order to model crash occurrence at signalized intersections more efficiently and eventually to better identify the significant factors contributing to crashes, this dissertation investigated the temporal, spatial, and site correlations for total, rear-end, right-angle and left-turn crashes. Using the basic regression model for correlated crash data leads to invalid statistical inference, due to incorrect test statistics and standard errors based on the misspecified variance. In this dissertation, the Generalized Estimating Equations (GEEs) were applied, which provide an extension of generalized linear models to the analysis of longitudinal or clustered data. A series of frequency models are presented by using the GEE with a Negative Binomial as the link function. The GEE models for the crash frequency per year (using four correlation structures) were fitted for longitudinal data; the GEE models for the crash frequency per intersection (using three correlation structures) were fitted for the signalized intersections along corridors; the GEE models were applied for the rear-end crash data with temporal or spatial correlation separately. For right-angle crash frequency, models at intersection, roadway, and approach levels were fitted and the roadway and approach level models were estimated by using the GEE to account for the "site correlation"; and for left-turn crashes, the approach level crash frequencies were modeled by using the GEE with a Negative Binomial link function for most patterns and using a binomial logit link function for the pattern having a higher proportion of zeros and ones in crash frequencies. All intersection geometry design features, traffic control and operational features, traffic flows, and crashes were obtained for selected intersections. Massive data collection work has been done. The autoregression structure is found to be the most appropriate correlation structure for both intersection temporal and spatial analyses, which indicates that the correlation between the multiple observations for a certain intersection will decrease as the time-gap increase and for spatially correlated signalized intersections along corridors the correlation between intersections decreases as spacing increases. The unstructured correlation structure was applied for roadway and approach level right-angle crashes and also for different patterns of left-turn crashes at the approach level. Usually two approaches at the same roadway have a higher correlation. At signalized intersections, differences exist in traffic volumes, site geometry, and signal operations, as well as safety performance on various approaches of intersections. Therefore, modeling the total number of left-turn crashes at intersections may obscure the real relationship between the crash causes and their effects. The dissertation modeled crashes at different levels. Particularly, intersection, roadway, and approach level models were compared for right-angle crashes, and different crash assignment criteria of "at-fault driver" or "near-side" were applied for disaggregated models. It shows that for the roadway and approach level models, the "near-side" models outperformed the "at-fault driver" models. Variables in traffic characteristics, geometric design features, traffic control and operational features, corridor level factor, and location type have been identified to be significant in crash occurrence. In specific, the safety relationship between crash occurrence and traffic volume has been investigated extensively at different studies. It has been found that the logarithm of traffic volumes per lane for the entire intersection is the best functional form for the total crashes in both the temporal and spatial analyses. The studies of right-angle and left-turn crashes confirm the assumption that the frequency of collisions is related to the traffic flows to which the colliding vehicles belong and not to the sum of the entering flows; the logarithm of the product of conflicting flows is usually the most significant functional form in the model. This study found that the left-turn protection on the minor roadway will increase rear-end crash occurrence, while the left-turn protection on the major roadway will reduce rear-end crashes. In addition, left-turn protection reduces Pattern 5 left-turn crashes (left-turning traffic collides with on-coming through traffic) specifically, but it increases Pattern 8 left-turn crashes (left-turning traffic collides with near-side crossing through traffic), and it has no significant effect on other patterns of left-turn crashes. This dissertation also investigated some other factors which have not been considered before. The safety effectiveness of many variables identified in this dissertation is consistent with previous studies. Some variables have unexpected signs and a justification is provided. Injury severity also has been studied for Patterns 5 left-turn crashes. Crashes were located to the approach with left-turning vehicles. The "site correlation" among the crashes occurred at the same approach was considered since these crashes may have similar propensity in crash severity. Many methodologies and applications have been attempted in this dissertation. Therefore, the study has both theoretical and implementational contribution in safety analysis at signalized intersections.Ph.D.
Department of Civil and Environmental Engineering
Engineering and Computer Science
Civil Engineering
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Decker, Jason John. "Orientation and spatial correlation of wire resistance fluctuations in still air." Diss., Online access via UMI:, 2007.
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Weidenbacher, Hollis Jean. "Subjective contours in the absence of local spatial and temporal correlation." Diss., The University of Arizona, 1993. http://hdl.handle.net/10150/186420.
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Subjective contours provide an opportunity to explore the limits of correspondence matching in motion. A new class of subjective contour which is a by-product of motion processing is examined within the context of the dual process models of retinal motion processing proposed by Braddick (1980) and Anstis (1980), as well as the more recent first-order/second-order formulation proposed by Cavanagh and Mather (1989). These kinetically induced figures are created by displacing a surface defined by dots which change randomly from frame to frame over a static random dot background. Despite the fact that local form information is uncorrelated throughout the motion sequence, the resulting phenomenal percept is that of a "sparkling" surface which translates across the background. The results of five experiments were not, however, fully consistent with predictions based on either model. An extension of the criteria necessary for the long-range system to be operative would accommodate the data within the context of the short-range/long-range model, whereas a more detailed definition of the properties and relationships between second-order attributes would accommodate the data within the framework of the first-order/second-order model.
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Tupikina, Liubov. "Temporal and spatial aspects of correlation networks and dynamical network models." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät, 2017. http://dx.doi.org/10.18452/17746.
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In der vorliegenden Arbeit untersuchte ich die komplexen Strukturen von Netzwerken, deren zeitliche Entwicklung, die Interpretationen von verschieden Netzwerk-Massen und die Klassen der Prozesse darauf. Als Erstes leitete ich Masse für die Charakterisierung der zeitlichen Entwicklung der Netzwerke her, um räumlich Veränderungsmuster zu erkennen. Als Nächstes führe ich eine neue Methode zur Konstruktion komplexer Netzwerke von Flussfeldern ein, bei welcher man das Set-up auch rein unter Berufung Berufung auf das Geschwindigkeitsfeld ändern kann. Diese Verfahren wurden für die Korrelationen skalarer Grössen, z. B. Temperatur, entwickelt, welche eine Advektions-Diffusions-Dynamik in der Gegenwart von Zwingen und Dissipation. Die Flussnetzwerk-Methode zur Zeitreihenanalyse konstruiert die Korrelationsmatrizen und komplexen Netzwerke. Dies ermöglicht die Charakterisierung von Transport in Flüssigkeiten, die Identifikation verschiedene Misch-Regimes in dem Fluss und die Anwendung auf die Advektions-DiffusionsDynamik, Klimadaten und anderen Systemen, in denen Teilchentransport eine entscheidende Rolle spielen. Als Letztes, entwickelte ich ein neuartiges Heterogener Opinion Status Modell (HOpS) und Analysetechnik basiert auf Random Walks und Netzwerktopologie Theorien, um dynamischen Prozesse in Netzwerken zu studieren, wie die Verbreitung von Meinungen in sozialen Netzwerken oder Krankheiten in der Gesellschaft. Ein neues Modell heterogener Verbreitung auf einem Netzwerk wird als Beispielssystem für HOpS verwendent, um die vergleichsweise Einfachheit zu nutzen. Die Analyse eines diskreten Phasenraums des HOPS-Modells hat überraschende Eigenschaften, welches sensibel auf die Netzwerktopologie reagieren. Sie können verallgemeinert werden, um verschiedene Klassen von komplexen Netzwerken zu quantifizieren, Transportphänomene zu charakterisieren und verschiedene Zeitreihen zu analysieren.In the thesis I studied the complex architectures of networks, the network evolution in time, the interpretation of the networks measures and a particular class of processes taking place on complex networks. Firstly, I derived the measures to characterize temporal networks evolution in order to detect spatial variability patterns in evolving systems. Secondly, I introduced a novel flow-network method to construct networks from flows, that also allows to modify the set-up from purely relying on the velocity field. The flow-network method is developed for correlations of a scalar quantity (temperature, for example), which satisfies advection-diffusion dynamics in the presence of forcing and dissipation. This allows to characterize transport in the fluids, to identify various mixing regimes in the flow and to apply this method to advection-diffusion dynamics, data from climate and other systems, where particles transport plays a crucial role. Thirdly, I developed a novel Heterogeneous Opinion-Status model (HOpS) and analytical technique to study dynamical processes on networks. All in all, methods, derived in the thesis, allow to quantify evolution of various classes of complex systems, to get insight into physical meaning of correlation networks and analytically to analyze processes, taking place on networks.
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Onal, Murat. "Evaulation Of Spatial And Spatio-temporal Regularization Approaches In Inverse Problem Of Electrocardiography." Master's thesis, METU, 2008. http://etd.lib.metu.edu.tr/upload/2/12610045/index.pdf.
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Conventional electrocardiography (ECG) is an essential tool for investigating cardiac disorders such as arrhythmias or myocardial infarction. It consists of interpretation of potentials recorded at the body surface that occur due to the electrical activity of the heart. However, electrical signals originated at the heart suffer from attenuation and smoothing within the thorax, therefore ECG signal measured on the body surface lacks some important details. The goal of forward and inverse ECG problems is to recover these lost details by estimating the heart’
s electrical activity non-invasively from body surface potential measurements. In the forward problem, one calculates the body surface potential distribution (i.e. torso potentials) using an appropriate source model for the equivalent cardiac sources. In the inverse problem of ECG, one estimates cardiac electrical activity based on measured torso potentials and a geometric model of the torso. Due to attenuation and spatial smoothing that occur within the thorax, inverse ECG problem is ill-posed and the forward model matrix is badly conditioned. Thus, small disturbances in the measurements lead to amplified errors in inverse solutions. It is difficult to solve this problem for effective cardiac imaging due to the ill-posed nature and high dimensionality of the problem. Tikhonov regularization, Truncated Singular Value Decomposition (TSVD) and Bayesian MAP estimation are some of the methods proposed in literature to cope with the ill-posedness of the problem. The most common approach in these methods is to ignore temporal relations of epicardial potentials and to solve the inverse problem at every time instant independently (column sequential approach). This is the fastest and the easiest approach
however, it does not include temporal correlations. The goal of this thesis is to include temporal constraints as well as spatial constraints in solving the inverse ECG problem. For this purpose, two methods are used. In the first method, we solved the augmented problem directly. Alternatively, we solve the problem with column sequential approach after applying temporal whitening. The performance of each method is evaluated.
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Ozdemir, Mehmet Kemal. "A spatial correlation analysis and adaptive estimation techniques for MIMO-OFDM systems." Related electronic resource: Current Research at SU : database of SU dissertations, recent titles available full text, 2005. http://wwwlib.umi.com/cr/syr/main.
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Conlon, Erin Marie. "Estimation and flexible correlation structures in spatial hierarchical models of disease mapping /." Diss., ON-CAMPUS Access For University of Minnesota, Twin Cities Click on "Connect to Digital Dissertations", 1999. http://www.lib.umn.edu/articles/proquest.phtml.
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Morano, Kaitlin. "Measuring the spatial correlation between temperature and vulnerability across the urban environment." Thesis, Georgia Institute of Technology, 2014. http://hdl.handle.net/1853/53028.
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This thesis aims to examine the spatial relationship between elevated air temperatures and populations most vulnerable to heat across the urban environment. To assess this correlation, the analysis focuses on the cities of Atlanta, Georgia and Minneapolis, Minnesota. A three-part methodology was employed: first, continuous air temperature was estimated using satellite imagery and weather station observations; second, a heat vulnerability index was generated based on demographic, social, and environmental variables at the Census block group level; and third, a spatial statistical analysis was performed to measure the correlation between the hottest temperatures and the populations most vulnerable to heat. Finally, the thesis concludes with policy recommendations that address the comprehensive nature of vulnerability in relation to extreme heat. As municipalities and local governments plan for a future with warmer temperatures and larger urban populations, effective policies must be designed with respect to both the social and physical environments; the results herein can help inform such strategies.
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Marjerison, William M. "Bayesian Logistic Regression with Spatial Correlation: An Application to Tennessee River Pollution." Digital WPI, 2006. https://digitalcommons.wpi.edu/etd-theses/1115.
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"We analyze data (length, weight and location) from a study done by the Army Corps of Engineers along the Tennessee River basin in the summer of 1980. The purpose is to predict the probability that a hypothetical channel catfish at a location studied is toxic and contains 5 ppm or more DDT in its filet. We incorporate spatial information and treate it separetely from other covariates. Ultimately, we want to predict the probability that a catfish from the unobserved location is toxic. In a preliminary analysis, we examine the data for observed locations using frequentist logistic regression, Bayesian logistic regression, and Bayesian logistic regression with random effects. Later we develop a parsimonious extension of Bayesian logistic regression and the corresponding Gibbs sampler for that model to increase computational feasibility and reduce model parameters. Furthermore, we develop a Bayesian model to impute data for locations where catfish were not observed. A comparison is made between results obtained fitting the model to only observed data and data with missing values imputed. Lastly, a complete model is presented which imputes data for missing locations and calculates the probability that a catfish from the unobserved location is toxic at once. We conclude that length and weight of the fish have negligible effect on toxicity. Toxicity of these catfish are mostly explained by location and spatial effects. In particular, the probability that a catfish is toxic decreases as one moves further downstream from the source of pollution."
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Mohamied, Yumnah. "Multidirectional near-wall flow in arteries and its spatial correlation with atherosclerosis." Thesis, Imperial College London, 2016. http://hdl.handle.net/10044/1/44374.
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Atherosclerotic lesions develop non-uniformly throughout the arterial system and their distribution around branches changes with age. This thesis investigates whether multidirectional blood flow, characterised by the transverse wall shear stress metric (transWSS), is related to the initiation of atherosclerosis. The spectral/hp element method was used to simulate pulsatile blood flow in immature and mature rabbit aortic geometries obtained by microCT of vascular corrosion casts. Bootstrapping was used to quantitatively correlate spatial maps around intercostal branch ostia, and found that the low/oscillatory shear theory did not correlate with disease, and could not account for age-related changes in macromolecule uptake. However, evidence for the multidirectional theory was found: transWSS related strongly and positively with disease at both ages and with wall permeability in young rabbits. The pulsatility of the blood is necessary for the existence of multidirectionality, yet the precise nature of the cardiac waveform did not dominantly influence both the large- and small-scale pattern of transWSS. Simulations in partially-idealised vessels revealed that geometry instead was crucial. Vessel curvature was responsible for a Dean vortex pair, whose changing strength over the cardiac cycle created changes in the shear direction at the wall, resulting in two large-scale axial streaks of high transWSS. Vessel torsion determined the asymmetry in their strengths and spatial locations over the descending aorta. Two distributions of transWSS resembling the age-dependent lesion patterns were identified at the individual-branch level, but which arose equally in both age groups. The small-scale patterns were found to depend on the branch's location with respect to the large-scale streaks, and therefore primarily on torsion, for which no statistically significant difference between age groups was found. Multidirectional flow relates well to disease at the aggregate-level and may explain age-dependent lesion patterns. The importance of geometry was highlighted, and calls into question how accurately it is captured.
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Chen, Xiaoding. "Exploring Temporal and Spatial Correlations on Circuit Variables for Enhancing Simulation-based Test Generation." Diss., Virginia Tech, 2006. http://hdl.handle.net/10919/28342.
Full textAbstract:
The ever-increasing complexity and size of current circuit designs have made testing and verification major bottlenecks in the design flow of VLSI (Very Large Scale Integrated) circuits. Statistics show that more than 70% of the design effort can be spent on functional verification and manufacturing testing. This percentage is expected to increase in the future if no significant strides in these areas are made. In this dissertation, we target three related problems in simulation-based Design
Verification and Testing: Sequential ATPG (Automatic Test Pattern Generation), Unbounded
Model Checking (UMC) of safety properties, and low power testing for full-scan sequential circuits. We model these three problems as simulation-based pattern generation problems and exploit novel ATPG algorithms to increase the effectiveness of sequential ATPGs.
The main challenge for fault/error detection in sequential circuits is the large number of flip-flops (FFs) in modern designs. Due to the large number and variable length of test sequences required for such circuits, the existing deterministic ATPG algorithms fail to achieve high test coverages. Such algorithms typically work by first unrolling the sequential circuit and then performing frequent backtracking to generate test vectors for fault detection. For the hard-to-detect faults, these schemes either run out of memory or require a huge computational effort. We show that simulationbased ATPGs, on the other hand, scale very well for large circuits as they perform only forward simulation. A fundamental problem associated with simulation-based ATPGs is to avoid exhaustive circuit simulation, which is impractical for large designs in the real world, by choosing high quality test vectors that achieve a high test coverage within a low simulation time. We tackle this primary problem by exploiting different correlation-based heuristics.
The intuition behind using correlation-based heuristics is to better guide the pattern generation engine such that the specific objective of either fault detection or property verification in UMC or minimizing power consumption during the testing, is achieved in an efficient manner without resorting to exhaustive simulation. In particular, we model and explore the following correlations: (1) temporal correlations, i.e. correlations on each primary input (PI) in different time frames, and
(2) spatial correlations, i.e. correlations among different FFs in the same time frame. We employ temporal correlations in the context of pattern generation of a built-in-self-test (BIST) architecture and we explore spatial correlations to guide a logic-simulation-based sequential ATPG and low power scan test generation. Experimental results on ISCAS and ITC benchmark circuits have shown that those correlations can enhance the simulation to discover more faults or design errors in a significantly shorter time.
Ph. D.
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Jain, Monika. "Regularized ensemble correlation filter tracking." Thesis, Queensland University of Technology, 2022. https://eprints.qut.edu.au/229266/1/Monika_Jain_Thesis.pdf.
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Visual Object Tracking is the task of tracking an object within a video. Broadly, most tracking algorithms can be classified into neural network based, correlation filter based, and hybrid. This thesis investigates various methods to improve tracking using correlation filters. The thesis contributes four novel trackers. The first tracker uses an appearance model pool to avoid faulty filter updates. Next, the appearance feature channel weights are learned using the graph-based similarity followed by modelling sparse spatio-temporal variations. At last, non-linearity of the appearance features is captured. The thesis also presents extensive evaluation of the proposed trackers on standard datasets.
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Apanasovich, Tatiyana Vladimirovna. "Testing for spatial correlation and semiparametric spatial modeling of binary outcomes with application to aberrant crypt foci in colon carcinogenesis experiments." Diss., Texas A&M University, 2004. http://hdl.handle.net/1969.1/2674.
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In an experiment to understand colon carcinogenesis, all animals were exposed to a carcinogen while half the animals were also exposed to radiation. Spatially, we measured the existence of aberrant crypt foci (ACF), namely morphologically changed colonic crypts that are known to be precursors of colon cancer development. The biological question of interest is whether the locations of these ACFs are spatially correlated: if so, this indicates that damage to the colon due to carcinogens and radiation is localized. Statistically, the data take the form of binary outcomes (corresponding to the existence of an ACF) on a regular grid. We develop score??type methods based upon the Matern and conditionally autoregression (CAR) correlation models to test for the spatial correlation in such data, while allowing for nonstationarity. Because of a technical peculiarity of the score??type test, we also develop robust versions of the method. The methods are compared to a generalization of Moran??s test for continuous outcomes, and are shown via simulation to have the potential for increased power. When applied to our data, the methods indicate the existence of spatial correlation, and hence indicate localization of damage. Assuming that there are correlations in the locations of the ACF, the questions are how great are these correlations, and whether the correlation structures di?er when an animal is exposed to radiation. To understand the extent of the correlation, we cast the problem as a spatial binary regression, where binary responses arise from an underlying Gaussian latent process. We model these marginal probabilities of ACF semiparametrically, using ?xed-knot penalized regression splines and single-index models. We ?t the models using pairwise pseudolikelihood methods. Assuming that the underlying latent process is strongly mixing, known to be the case for many Gaussian processes, we prove asymptotic normality of the methods. The penalized regression splines have penalty parameters that must converge to zero asymptotically: we derive rates for these parameters that do and do not lead to an asymptotic bias, and we derive the optimal rate of convergence for them. Finally, we apply the methods to the data from our experiment.
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Moughton, Lynette Jane. "Effect of Temporal and Spatial Aggregation on Cross Correlation of Indoor Residential Water Demands." University of Cincinnati / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1250351156.
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Sjöström, Lars. "The spatial distribution of birds in southern Sweden : A descriptive study of willow warbler, nightingale, blackbird, robin and grey flycatcher in Svealand and Götaland." Thesis, Uppsala universitet, Statistiska institutionen, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-275343.
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This is a thesis about the spatial distribution of willow warbler, nightingale, blackbird, robin and grey flycatcher in Svealand and Götaland, that is the southern third of Sweden. It explores the possibilities of using statistics to describe the distribution and variation of birds in a given region.The data was collected by observation of birds on sites called standard routes, with 25 kilometres between them. The standard routes are the points in a grid net placed upon the map of Sweden. The purpose of standard routes is to represent the birds in Sweden both geographic and biotopological.The thesis compare the results from kriging, variogram and four alternative poisson regressions. In the end I come up with the information provided by kriging and variogram and which poisson regression that bests estimates the population sizes of the birds at a given site with information about year, mean temperature from January to May and what kind of environment or habitat the site consist of.
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Andre, Maina. "Proposition d'un modèle de prévision spatio-temporel à court terme de l'ensoleillement global, à partir de trois sites en Guadeloupe." Thesis, Antilles, 2015. http://www.theses.fr/2015ANTI0009/document.
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En Guadeloupe, actuellement, 5,92% de la demande en énergie électrique sont couverts par la filière photovoltaïque et 3,14% par la filière éolienne soit 9,06% pour leur production cumulée selon le bilan 2015 de l’OREC (Observatoire Régional de l’Energie et du Climat). Selon le plan énergétique régional de prospection, la production cumulée du photovoltaïque et de l’éolien devrait représenter 14% du mix électrique en 2020 et 18% en 2030. Pour atteindre les 14% du mix électrique d’ici les cinq prochaines années, il va donc falloir entre autres, améliorer la prédictibilité pour un développement à un rythme soutenu de ces énergies. Ces travaux de recherches ont consisté à apporter de nouveaux résultats de performance de prévision de l’ensoleillement global à court terme et à donner une connaissance plus fine de la ressource sur trois stations en Guadeloupe. L’étude est basée sur une analyse et un modèle de prévision de l’ensoleillement, faisant intervenir des paramètres spatiaux et temporels. La littérature montre qu’un important nombre de sites est en général utilisé pour une analyse spatio-temporelle, ce qui impliquerait pour nous, de poser de multiples capteurs sur l’ensemble du territoire. Les coûts d’un tel système seraient considérables. Notre approche ici consistera à effectuer une analyse spatio-temporelle sur trois stations. Avec peu de stations et des distances non uniformes nous avons donc cherché à développer un modèle de prévision de l’ensoleillement à court terme en dépit de ces contraintes qui ne répondent pas à une approche classique. Le modèle est basé sur une méthodologie VAR (Vecteur Autorégressif) incluant des paramètres spatiaux et temporels. Une stratégie de sélection des variables est développée afin de sélectionner les prédicteurs (stations) utiles pour la prévision sur une localisation. Cette stratégie itérative permettra d’une part d’être plus proche de la réalité, d’autre part d’un point de vue algorithmique, la tendance des calculs sera plus rapide. En amont du développement du modèle, une étude de la variabilité spatio-temporelle de l’ensoleillement a permis de quantifier et caractériser de manière fine, les interactions dynamiques entre ces trois stations. Par comparaison avec les modèles de la littérature, notre modèle de prévision montre une bonne performance avec des valeurs de RMSE relative allant de 17,48% à 23,79% pour des horizons de prévisions de 5 min à 1h. Les méthodologies développées pourraient à terme offrir une opportunité d’assurer des garanties au gestionnaire du réseau. Si d'avenir des solutions de prévision performantes se généralisaient, cette opportunité permettrait d’ouvrir le marché au-delà du seuil de 30% imposé actuellementCurrently in Guadeloupe, there is 5,92 % of the electric power request covered by the photovoltaic sector and 3,14 % by the wind sector which represents 9,06 % for their accumulated production, according to the OREC report (Regional Monitoring center of Energy and Climate). According to the regional energy plan, the accumulated production of the photovoltaic and the wind energy should represent 14 % of the electric mix in 2020 and 18 % in 2030. To reach the 14 % of the electric mix within the next five years, we need, among other things, to improve forecast for a sustained development of these energies. These research works consisted in bringing new performance results of short-term forecast of the global solar radiation and in giving a finer knowledge of the resource onto three stations in Guadeloupe. The study is based on an analysis and a forecast model of global solar radiation, by including spatial and temporal parameters. The literature shows that an important number of sites is generally used for a spatio-temporal analysis, which would imply for us, to put multiple sensors on the whole territory. The costs of such a system would be considerable. Our approach here will consist in making a spatiotemporal analysis on three stations. With few stations and not uniform distances, we, thus, tried to define a short-term forecast model of global solar radiation, in spite of these constraints which do not answer to a classic approach. The model is based on a methodology the VAR ( Autoregressive Vector) including spatial and temporal parameters. A strategy of selection of variables is developed to select useful predictors (stations) for the forecast on localization. This iterative strategy, on one hand will allow being closer to the reality, on the other hand to the point of algorithmic view, the trend of the calculations will be faster. Preliminarily, a study of the spatiotemporal variability of global solar radiation, allowed to quantify and to characterize in a fine way, the dynamic interactions between these three stations. Compared with the models of the literature, our forecast model shows a good performance with relative RMSE values going from 17.48 % to 23.79 % for horizons from 5 min to 1 hour. The developed methodologies could eventually offer an opportunity to assure guarantees to the network manager. If in the future the successful solutions of forecast became widespread, this opportunity would allow the opening of the market beyond the 30 % threshold imposed at present
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Kanaan, Mona N. "Cross-spectral analysis for spatial point-lattice processes." Thesis, [n.p.], 2000. http://dart.open.ac.uk/abstracts/page.php?thesisid=94.
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SHARMA, ANURAG. "EXPLOITING SPATIAL CORRELATION USING TREE BASED POLYNOMIAL REGRESSION IN A THREE DIMENSIONAL WIRELESS SENSOR NETWORK." University of Cincinnati / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1175107970.
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BANERJEE, SUMON. "Spatial and Temporal Correlation and Extracting Critical Attribute in a Three dimensional Wireless Sensor Network." University of Cincinnati / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1214590299.
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Persiano, Simone <1989>. "Catchment similarity and spatial correlation: added value and impacts on hydrological predictions in ungauged basins." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2019. http://amsdottorato.unibo.it/8952/1/PhDThesis_SimonePersiano.pdf.
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This Thesis presents a three-fold study aimed at deepening our understanding on the added value and impacts of catchment similarity and spatial correlation (or cross-correlation) on the regional prediction of flood quantiles and flow-duration curves (FDCs) in ungauged river cross-sections. First, we consider the reference procedure for design flood estimation in Triveneto, North-eastern Italy, which assumes the entire study area to be a single hydrologically homogeneous region. We highlight that Triveneto cannot be regarded as homogeneous in terms of flood frequency regime and show that a focused-pooling approach accounting for selected geomorphoclimatic descriptors leads to regional samples with significantly improved homogeneity. Nevertheless, focused pooling does not consider the effects associated with cross-correlation, which are instead considered by Generalized Least Squares (GLS) and Top-kriging (TK; geostatistical method), although in two different ways. Recent studies show that TK outperforms GLS for predicting empirical flood quantiles, but they also speculate that cross-correlation might affect their accuracy in predicting true flood quantiles. To investigate this aspect, we apply GLS and TK for predicting flood quantiles in a homogeneous pooling-group of sites in Triveneto under different cross-correlation scenarios through a Monte Carlo experiment. For both methods, we observe that an increasing degree of spatial correlation results in an increasing masking-effect on the true flooding potential. Morever, we confirm that TK significantly outperforms GLS when they both assume flood quantiles to scale with drainage area alone, yet, both methodologies significantly improve their accuracy when considering several catchment descriptors. Finally, concerning the prediction of FDCs in a large and heterogeneous region, the Danube river basin, we show that geostatistical models provide much more accurate predictions than multi-regression models. In summary, all the analyses confirm the added value for statistical regionalisation of properly handling hydrological heterogeneity, also highlighting the pivotal role played by cross-correlation in observed streamflow time-series.
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Assefa, Yared. "Time series and spatial analysis of crop yield." Thesis, Kansas State University, 2012. http://hdl.handle.net/2097/15142.
Full textAbstract:
Master of ScienceDepartment of Statistics
Juan Du
Space and time are often vital components of research data sets. Accounting for and utilizing the space and time information in statistical models become beneficial when the response variable in question is proved to have a space and time dependence. This work focuses on the modeling and analysis of crop yield over space and time. Specifically, two different yield data sets were used. The first yield and environmental data set was collected across selected counties in Kansas from yield performance tests conducted for multiple years. The second yield data set was a survey data set collected by USDA across the US from 1900-2009. The objectives of our study were to investigate crop yield trends in space and time, quantify the variability in yield explained by genetics and space-time (environment) factors, and study how spatio-temporal information could be incorporated and also utilized in modeling and forecasting yield. Based on the format of these data sets, trend of irrigated and dryland crops was analyzed by employing time series statistical techniques. Some traditional linear regressions and smoothing techniques are first used to obtain the yield function. These models were then improved by incorporating time and space information either as explanatory variables or as auto- or cross- correlations adjusted in the residual covariance structures. In addition, a multivariate time series modeling approach was conducted to demonstrate how the space and time correlation information can be utilized to model and forecast yield and related variables. The conclusion from this research clearly emphasizes the importance of space and time components of data sets in research analysis. That is partly because they can often adjust (make up) for those underlying variables and factor effects that are not measured or not well understood.
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Bhattacharyya, Rangeet. "Methodological Developments In NMR Using Cross-correlations And Spatial Encoding." Thesis, Indian Institute of Science, 2005. https://etd.iisc.ac.in/handle/2005/194.
Full textAbstract:
This thesis aims at the methodological developments in Nuclear Magnetic Resonance
(NMR). The methodological developments in NMR has a long and successful history. The
present thesis attempts to contribute some novel methods in this direction.
This thesis restricts itself to two methodological developments, namely, (1) effects
of cross-correlations between the chemical shift anisotropy (CSA) and dipole-dipole
interactions in the relaxation of various nuclei and experiments which utilize spatial
encoding. The cross-correlation has been successfully utilized to investigate the anisotropic
motions of liquid crystals, and to understand the chemical shift anisotropy of fluorine atoms
of Fluorine substituted ring compounds. Spatial encoding schemes have been developed
to facilitate single scan measurements of longitudinal spin lattice relaxation times and
implementations of parallel search algorithms.
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Bhattacharyya, Rangeet. "Methodological Developments In NMR Using Cross-correlations And Spatial Encoding." Thesis, Indian Institute of Science, 2005. http://hdl.handle.net/2005/194.
Full textAbstract:
This thesis aims at the methodological developments in Nuclear Magnetic Resonance
(NMR). The methodological developments in NMR has a long and successful history. The
present thesis attempts to contribute some novel methods in this direction.
This thesis restricts itself to two methodological developments, namely, (1) effects
of cross-correlations between the chemical shift anisotropy (CSA) and dipole-dipole
interactions in the relaxation of various nuclei and experiments which utilize spatial
encoding. The cross-correlation has been successfully utilized to investigate the anisotropic
motions of liquid crystals, and to understand the chemical shift anisotropy of fluorine atoms
of Fluorine substituted ring compounds. Spatial encoding schemes have been developed
to facilitate single scan measurements of longitudinal spin lattice relaxation times and
implementations of parallel search algorithms.
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Bandreddy, Naga Abhiram. "Defining Correlation Between Radon, Uranium Deposits, and Oil and Gas Wells Using GIS Regression Methods." University of Toledo / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1564687565423414.
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Yokomizu, Yasunobu, Toshiro Matsumura, Akiji Matsuda, and Hideyuki Ohno. "Dependence of arc interrupting capability on spatial distribution of airflow velocity in air-blast flat-type quenching chamber." IEEE, 2003. http://hdl.handle.net/2237/6793.
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Gardner, Mark Charles. "Phase object pattern recognition by optical correlation using a liquid crystal display for spatial phase modulation." Thesis, University College London (University of London), 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.409700.
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DeVanna, Kristen M. "Spatial Correlation and Facilitation Between Dreissena and Hexagenia: Possible Food-Web Disruption?" University of Toledo / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1320935549.
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Smith, Mark E. "The Correlation Between a Pre-Engineering Student's Spatial Ability and Achievement in an Elecetronics Fundamentals Course." DigitalCommons@USU, 2009. https://digitalcommons.usu.edu/etd/254.
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Though there is ample evidence showing a positive relationship between a student's spatial ability and achievement in many fields of science, technology, and engineering, this study was seeking evidence that a relationship exists between a pre-engineering student's spatial ability and achievement in an electronics fundamentals course.
The importance of spatial ability to mentally design, develop, and manipulate images has been linked to measures of practical and mechanical abilities that are quite useful in technical occupations. Spatial abilities are frequently attributed to creative and higher order thinking skills in science and mathematics. Spatial imagery is tremendously important in art and creative thinking, and has an important role in abstract engineering disciplines such as electronics.
This study included 154 students enrolled in two sections of a fundamentals electronics course. The average age of the students enrolled in this course was 22.64 years old. The majority (89.6%) of the students was male, and 59.1% of the students majored in mechanical engineering. The average GPA of the participants was 3.4. The participants scored well on the spatial ability test (avg. 17.5, out of a possible 20), and the average grade received in the course was a B (avg. 85.6, out of a possible 100).
This study showed a highly significant (.000 alpha 1-tailed level) and near medium (Pearson's r of .29) correlation strength between spatial ability and achievement in the course. There was significant positive correlation between GPA and spatial ability--corroborating that pre-engineering students with high GPAs also have high spatial ability. When controlling for GPA in a partial correlation, it was found that spatial ability accounted for a significant amount of the variance in the semester scores, which suggests that spatial ability provides some good prediction of doing well in an electronics fundamentals course above and beyond what GPA predicts alone.
Many STEM subjects are at the atomic level and require using mental models that are created in the mind's eye and necessarily require spatial reasoning ability. The understanding of a given aspect of the physical world is best conceptualized with a mental model.
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Matthews, Kevin Andrew. "Spatiotemporal correlation analysis of colorectal cancer late-stage incidence, mortality, and survival: Iowa, 1999 to 2010." Diss., University of Iowa, 2018. https://ir.uiowa.edu/etd/6467.
Full textAbstract:
This study of the spatiotemporal patterns of colorectal cancer (CRC) in Iowa introduced the importance of examining the geographic patterns of four epidemiological measures (incidence, late-stage incidence, mortality, and survival) as inter-related phases in the natural history of the disease rather than as independent measures. To conduct such an analysis required the development of a framework for conducting spatiotemporal correlation analysis involving two or more measures across two or more periods.
This framework is based on geographic units called spatially adaptive filter areas.which effectively address the small number problem. This common spatial epidemiology problem occurs when the population in a unit of geography is too small to calculate a reliable disease rate. The spatially adaptive filter areas are created by aggregating smaller geographic units which, by themselves, do not have sufficiently large populations to calculate statistically reliable disease rates.
Conducting spatiotemporal analysis magnifies the small number problem because stratifying disease data by time further reduces the sample sizes in each period, thus increasing the potential for unreliable disease rates. This spatiotemporal framework satisfies two conditions: 1) the rates of each measure in all small areas in the study region meet a minimum level of statistical reliability in all periods, and 2) the disease outcomes measured for one period relies on the same geographic units as the rates calculated for all other periods and measures.
We applied the spatiotemporal framework to colorectal cancer data collected in the state of Iowa between 1999 and 2010. Using rates calculated in spatial filter areas, we found that the proportion of cases diagnosed at a late-stage among the population at risk for CRC is more correlated with CRC mortality than when late-stage is measured as the proportion of late-stage cases among the CRC cases diagnosed at any stage. We also found that, when measured in the context of the statewide change, an observed decline in the rate of CRC mortality in a small area does not necessarily mean that its level of mortality is improving. We also found that the correlation between rates of CRC mortality and the survival time among patients diagnosed with CRC varied across Iowa.
The results described in this dissertation could potentially reduce the burden of colorectal cancer and improve the health of communities by providing public health professionals and cancer control specialists with evidence to enhance their decision-making processes.
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Dai, Rui. "Correlation-based communication in wireless multimedia sensor networks." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/42736.
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Wireless multimedia sensor networks (WMSNs) are networks of interconnected devices that allow retrieving video and audio streams, still images, and scalar data from the environment. In a densely deployed WMSN, there exists correlation among the observations of camera sensors with overlapped coverage areas, which introduces substantial data redundancy in the network. In this dissertation, efficient communication schemes are designed for WMSNs by leveraging the correlation of visual information observed by camera sensors. First, a spatial correlation model is developed to estimate the correlation of visual information and the joint entropy of multiple correlated camera sensors. The compression performance of correlated visual information is then studied. An entropy-based divergence measure is proposed to predict the compression efficiency of performing joint coding on the images from correlated cameras. Based on the predicted compression efficiency, a clustered coding technique is proposed that maximizes the overall compression gain of the visual information gathered in WMSNs. The correlation of visual information is then utilized to design a network scheduling scheme to maximize the lifetime of WMSNs. Furthermore, as many WMSN applications require QoS support, a correlation-aware QoS routing algorithm is introduced that can efficiently deliver visual information under QoS constraints. Evaluation results show that, by utilizing the correlation of visual information in the communication process, the energy efficiency and networking performance of WMSNs could be improved significantly.
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Kapoor, Mudit. "Panel data models with spatial correlation estimation theory and empirical investigation of the US wholesale gasoline industry /." College Park, Md. : University of Maryland, 2003. http://hdl.handle.net/1903/143.
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Thesis (Ph. D.) -- University of Maryland, College Park, 2003.Thesis research directed by: Economics. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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Keil, Fabian [Verfasser]. "Investigation of spatial correlation in MR images of human cerebral white matter using geostatistical methods / Fabian Keil." Aachen : Hochschulbibliothek der Rheinisch-Westfälischen Technischen Hochschule Aachen, 2014. http://d-nb.info/1052254632/34.
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Baykas, Tuncer. "Effects of spatial correlation and channel estimation errors on the performance of space-time block coded systems." Thesis, University of Ottawa (Canada), 2002. http://hdl.handle.net/10393/6147.
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Today's wireless communication systems require more efficiency in terms of data rate. One of the ways to improve channel capacity of such systems is to utilize diversity. Space-time block codes provide transmit diversity gain without any significant increase in complexity of systems. However in some cases, the gain by utilizing diversity decreases due to some factors. In this work we studied two of these factors and their effects to several space-time block coded systems. The first factor is the spatial correlation among channels and the second factor is channel estimation errors. Both of these factors are experienced in real life situations. The systems under consideration are 2, 3 and 4 antenna orthogonal and quasi-orthogonal space-time block coded systems. We have also compared the results with the maximum ratio combining schemes with 2 and 4 receiver antennas.
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藍東鑫. "Spatial correlation analysis for component matching." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/91054779381462941639.
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碩士中華大學
電機工程學系碩士班
90
Component Matching is more important to the design of the modern analog and mixed-signal integrated circuits. In this thesis two circuit schemes consisted of successive reference generation and matching components are analyzed to elevate the effectiveness of spatial correlation. In the first scheme of successive reference generation, the associative non-linearity is discussed and it is to shown that the integral non-linearity error (INL) will be the hard burden. The component arrangement of space permutation is proposed and a good permutation is given by comparative to other cases. In the second scheme of component matching, it is to show the feasibility of desired correlation of matching components with respect to elementary component correlation.
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Lu, Yuan Jung, and 呂元戎. "Spatial Correlation Analysis for Successive Reference Generation." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/37152734236713284398.
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碩士中華大學
電機工程學系碩士班
91
This thesis discussed successive reference generation circuit and component’s correlation. Using spatial arrangement for component improve circuit’s linearity. We deduce regular one-dimension permutation which not only improve circuit’s linearity but also suppress graded error. Ours two-dimension permutation can get good linearity when components have low correlation.
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Syu, Yu-Sian, and 許育憲. "Surface Plasmon Resonance Spatial Correlation for Biosensing." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/9f2hjd.
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碩士國立臺灣科技大學
光電工程研究所
107
Early diagnostics of the disease can discover the body malfunctions and apply the appropriate treatment in an early stage. MicroRNA (miRNA) is a small non-coding RNA which functions in post-translational regulation of gene expression. The detection of miRNA expression level could be useful for cancer diagnosis in early stage. For disease diagnosis, the serum miRNAs can serve as potential biomarkers for the detection of various cancers and other diseases. However, the time cost of PCR (Polymerase chain Reaction)-based miRNA detection method still needs improved. The surface plasma resonance (SPR) sensor could detect the small dielectric constant variation at the interface between the solid and liquid or the solid and gas. The SPR spatial imaging system proposed in this project can observe the phase change from reflected light for miRNA-21 detection in real time and biomarkers free with high sensitivity. The typical SPR image sensor is using the multi-step algorithm to resolve the sensitivity and resolution through interference fringe images. A novel SPR image sensing system is proposed to utilize the prism for spatial correlated image analyses. The main functions are taking the windowed Fourier transform to analyze relative images interference displacements from various analytes besides the fringe visibility optimization through optical spectrum analyzer. In this thesis, the interference phase and image sensitivity for microRNA-21 DNA are characterized as -0.067 (rad/μM) and-7.5"×" 〖"10" 〗^"-2" （μm/μM） respectively.
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KUMAR, ANIL. "SPATIAL CORRELATION MODELS ANALYSIS FOR WIRELESS SENSOR NETWORK." Thesis, 2016. http://dspace.dtu.ac.in:8080/jspui/handle/repository/14839.
Full textAbstract:
Wireless sensor networks (WSN) are deployed very densely so that accurate monitoring can be achieved in many applications. For example, the deployment density can be as high as 20 nodes/m3[1]. As sensor nodes are deployed with high density, the information observed and transmitted by sensor nodes in an area at the time an event is occurred is spatially correlated. It means there is spatial correlation in the sensors observations. The spatial correlation along with collaborative nature of the Wireless sensor networks (WSN) has potential advantages in designing energy-efficient models of Communication protocols. There exists a spatial correlation function[7], which describes correlation characteristics of information sensed by sensor nodes, which is related to location and coverage model of sensor nodes. This paper presents a study of various cluster head selection algorithms and proposes an energy efficient model for wireless sensor network by exploiting spatial correlation among various sensor nodes of the network. Firstly, study the behavior of wireless sensor network without spatial correlation. Secondly, we divide entire wireless sensor network into clusters assuming spatial correlation among the observations within the nodes of a cluster. One of the nodes of the cluster is considered as Cluster Head (CH) on random selection and sends the observation to Base Station (BS). In last part of analysis we make one of the Cluster Head (CH) as super Node (SN) that aggregates observations from all Cluster Head (CHs) and sends information to Base Station (BS). Finally, based on the above analysis and their results we propose an energy efficient model for wireless sensor network.