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1
Orasch, Markus, Friedrich Leisch y Andreas Weingessel. "On specifying correlation matrices for binary data". SFB Adaptive Information Systems and Modelling in Economics and Management Science, WU Vienna University of Economics and Business, 1999. http://epub.wu.ac.at/486/1/document.pdf.
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We are interested in generating binary data via specifying the marginals and the correlation matrix only. However, from a practical point of view it is not obvious how to construct such a matrix, since it has to be positive (semi-)definite and satisfy some special conditions as well. Hence, using R, a free implementation of the S statistical language, we give a graphical interface to input specific marginals and correlations and to change the given "not working" correlation matrix to a possibly "working" one.Series: Working Papers SFB "Adaptive Information Systems and Modelling in Economics and Management Science"
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Pei, Yanbo. "Statistical inference for correlated binary data from bilateral studies". HKBU Institutional Repository, 2009. http://repository.hkbu.edu.hk/etd_ra/1077.
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Houston, Alice Elizabeth Dashwood. "On binary sequences with specific linear complexity and correlation properties". Thesis, Royal Holloway, University of London, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.307031.
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For many applications, such as cryptography and digital communications, binary sequences with certain specific properties are required. These include a balance of 0's and 1's in a period, ideal runs frequencies, good auto- and cross-correlation spectra, and high linear complexity. Perfect Linear Complexity Profile sequences (PLCPs) have the linear complexity of all subsequences (starting with the first bit) equal to half the length of the subsequence (this is the expected value for a random sequence). We investigate the density - proportion of ones - of finite length PLCPs, both in general and for specific examples. We gain results on the average, maximal and minimal densities, as well as their limits as the length tends to infinity. We also study whether the PLCP property is preserved under various decimations. PLCPs are characterised by a simple linear recurrence modulo 2. We look at similar "nearly" perfect profiles and characterise sequences with these profiles in terms of similar recurrences. Also sequences with a PLCP up to a point and then constant complexity are characterised in terms of the convergents in the continued fraction expansion of the generating function of PLCPs, and we look briefly at their corresponding periods. Sequences with bounded jumps in their linear complexity are discussed and a method of generating them is suggested. The interleaving of shifts of a sequence with out-of-phase auto-correlation equal to -1 and balance, in a specific order, seems to be a fundamental method of generating longer sequences with this auto-correlation property. It is shown that two pairs of families of these sequences, derived in different ways, are in fact equivalent. The analysis highlights the general method mentioned above, and so provides examples of families of sequences with 2-valued auto-correlation by changing the ingredients in the interleaving pattern. We also look at the cross-correlation of sequences with this interleaved structure.
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Hintze, Christopher Jerry. "Modeling correlation in binary count data with application to fragile site identification". Texas A&M University, 2005. http://hdl.handle.net/1969.1/4278.
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Available fragile site identification software packages (FSM and FSM3) assume
that all chromosomal breaks occur independently. However, under a Mendelian model of
inheritance, homozygosity at fragile loci implies pairwise correlation between
homologous sites. We construct correlation models for chromosomal breakage data in
situations where either partitioned break count totals (per-site single-break and doublebreak
totals) are known or only overall break count totals are known. We derive a
likelihood ratio test and NeymanâÂÂs C( ñ) test for correlation between homologs when
partitioned break count totals are known and outline a likelihood ratio test for correlation
using only break count totals. Our simulation studies indicate that the C( ñ) test using
partitioned break count totals outperforms the other two tests for correlation in terms of
both power and level. These studies further suggest that the power for detecting
correlation is low when only break count totals are reported. Results of the C( ñ) test for
correlation applied to chromosomal breakage data from 14 human subjects indicate that
detection of correlation between homologous fragile sites is problematic due to
sparseness of breakage data. Simulation studies of the FSM and FSM3 algorithms using
parameter values typical for fragile site data demonstrate that neither algorithm is
significantly affected by fragile site correlation. Comparison of simulated fragile site
misclassification rates in the presence of zero-breakage data supports previous studies
(Olmsted 1999) that suggested FSM has lower false-negative rates and FSM3 has lower
false-positive rates.
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Svensson, Patrik. "Machine learning techniques for binary classification of microarray data with correlation-based gene selection". Thesis, Uppsala universitet, Statistiska institutionen, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-302402.
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Microarray analysis has made it possible to predict clinical outcomes or diagnosing patients with the help of biological data such as biomarkers or gene expressions. The data from microarrays are however characterized by high dimensionality and sparsity so that traditional statistical methods are difficult to use and machine learning algorithms are therefore applied for classification and prediction. In this thesis, five different machine learning algorithms were applied on four different microarray datasets from cancer studies and evaluated in terms of cross-validation performance and classification accuracy. A correlation-based gene selection method was also applied in order to reduce the amount of genes with the aim of improving accuracy of the algorithms. The findings of the thesis imply that the algorithm s elastic net and nearest shrunken centroid perform best on datasets with no gene selection, while support vector machine and random forest perform well on the reduced datasets with gene selection. However, no machine learning algorithm can be said to consistently outperform any of the other and the nature of the dataset seem to be a more important influence on the performance of the algorithm. The correlation-based gene selection method did however improve prediction accuracy of all the models by removing irrelevant genes.
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Zhang, Yanwei. "A hierarchical Bayesian approach to model spatially correlated binary data with applications to dental research". Diss., Connect to online resource - MSU authorized users, 2008.
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Ramm, David John. "A spectroscopic study of detached binary systems using precise radial velocities". Thesis, University of Canterbury. Physics and Astronomy, 2004. http://hdl.handle.net/10092/1525.
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Spectroscopic orbital elements and/or related parameters have been determined for eight binary systems, using radial-velocity measurements that have a typical precision of about 15 ms⁻¹. The orbital periods of these systems range from about 10 days to 26 years, with a median of about 6 years. Orbital solutions were determined for the seven systems with shorter periods. The measurement of the mass ratio of the longest-period system, HD217166, demonstrates that this important astrophysical quantity can be estimated in a model-free manner with less than 10% of the orbital cycle observed spectroscopically.\\ Single-lined orbital solutions have been derived for five of the binaries. Two of these systems are astrometric binaries: β Ret and ν Oct. The other SB1 systems were 94 Aqr A, θ Ant, and the 10-day system, HD159656. The preliminary spectroscopic solution for θ Ant (P~18 years), is the first one derived for this system. The improvement to the precision achieved for the elements of the other four systems was typically between 1--2 orders of magnitude. The very high precision with which the spectroscopic solution for HD159656 has been measured should allow an investigation into possible apsidal motion in the near future. In addition to the variable radial velocity owing to its orbital motion, the K-giant, ν Oct, has been found to have an additional long-term irregular periodicity, attributed, for the time being, to the rotation of a large surface feature.\\ Double-lined solutions were obtained for HD206804 (K7V+K7V), which previously had two competing astrometric solutions but no spectroscopic solution, and a newly discovered seventh-magnitude system, HD181958 (F6V+F7V). This latter system has the distinction of having components and orbital characteristics whose study should be possible with present ground-based interferometers. All eight of the binary systems have had their mass ratio and the masses of their components estimated.\\ The following comments summarize the motivation for getting these results, and the manner in which the research was carried out. \\ The majority of stars exist in binary systems rather than singly as does the Sun. These systems provide astronomers with the most reliable and proven means to determine many of the fundamental properties of stars. One of these properties is the stellar mass, which is regarded as being the most important of all, since most other stellar characteristics are very sensitive to the mass. Therefore, empirical masses, combined with measurements of other stellar properties, such as radii and luminosities, are an excellent test for competing models of stellar structure and evolution.\\ Binary stars also provide opportunities to observe and investigate many extraordinary astrophysical processes that do not occur in isolated stars. These processes often arise as a result of direct and indirect interactions between the components, when they are sufficiently close to each other. Some of the interactions are relatively passive, such as the circularization of the mutual orbits, whilst others result from much more active processes, such as mass exchange leading to intense radiation emissions. \\ A complete understanding of a binary system's orbital characteristics, as well as the measurement of the all-important stellar masses, is almost always only achieved after the binary system has been studied using two or more complementary observing techniques. Two of the suitable techniques are astrometry and spectroscopy. In favourable circumstances, astrometry can deduce the angular dimensions of the orbit, the total mass of the system, and sometimes, its distance from us. Spectroscopy, on the other hand, can determine the linear scale of the orbit and the ratio of the stellar masses, based on the changing radial velocities of both stars. When a resolved astrometric orbital solution is also available, the velocities of both stars can allow the binary system's parallax to be determined, and the velocities of one star can provide a measure of the system mass ratio.\\ Unfortunately, relatively few binary systems are suited to these complementary studies. Underlying this difficulty are the facts that, typically, astrometrically-determined orbits favour those with periods of years or decades, whereas spectroscopic orbital solutions are more often measured for systems with periods of days to months. With the development of high-resolution astrometric and spectroscopic techniques in recent years, it is hoped that many more binary systems will be amenable to these complementary strategies.\\ Several months after this thesis began, a high-resolution spectrograph, HERCULES, commenced operations at the Mt John University Observatory, to be used in conjuction with the 1-metre McLellan telescope. For late-type stars, the anticipated velocity precision was ≲10 ms⁻¹. The primary goals of this thesis were: 1.~to assess the performance of HERCULES and the related reduction software that subsequently followed, 2.~to carry out an observational programme of 20 or so binary systems, and 3.~to determine the orbital and stellar parameters which characterize some of these systems. The particular focus was on those binaries that have resolved or unresolved astrometric orbital solutions, which therefore may be suited to complementary investigations.\\ HERCULES was used to acquire spectra of the programme stars, usually every few weeks, over a timespan of about three years. High-resolution spectra were acquired for the purpose of measuring precise radial velocities of the stars. When possible, orbital solutions were derived from these velocities, using the method of differential corrections.
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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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Fitzner, Arnas Gerald. "Effects of alloying elements on twinning in alpha-titanium alloys". Thesis, University of Manchester, 2015. https://www.research.manchester.ac.uk/portal/en/theses/effects-of-alloying-elements-on-twinning-in-alphatitanium-alloys(5d94e41b-face-40a9-b2d3-28223a2f28ad).html.
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It has been found that commercially pure (CP) Titanium (Ti) undergoes substantial amount of deformation twinning during plastic forming in a wide range of temperatures and strain rates giving CP-Ti good ductility and allowing up to 90% thickness reduction by cold rolling. Aluminium (Al) rich ! Ti-alloys lack this superior ductility but exhibit therefore up to five times higher yield strength, which was connected experimentally to reduced activity of deformation twinning with addition of Al to Ti. Ultimately this is also valid in the ! phase of two-phase alloys such as Ti6Al4V and thought to be key to the reduced ductility in Al rich alloys. It is to date unclear if ordering of Al in the Ti matrix, a change in the stacking fault energy (SFE) with alloying or a transition of the cellular dislocation structures in CP-Ti to planar slip patterns at high Al contents reduces twin activity. The focus of this dissertation project is therefore the transition of microstructural details and the deformation structures in the ! phase with increasing Al concentration. For simplified investigations binary Ti-Al alloys containing 3.5, 7, 10 and 13at.% Al have been created with comparable grain morphology and texture within this study. For a better understanding of the role of Al also binary Ti-Sn (Tin) alloys (1 & 3.4at.% Sn) and Ti-Zr (Zirconium) alloys (3.6 & 10at.%) as well as an Oxygen (O) rich Ti-10at.%Al and the industrial compositions of Ti6Al4V were produced on the same route and investigated by the same methods. This alloy range allows evaluation of the effects of the c/a ratio, ordering phenomena and the SFE on the twin activity. The knowledge was finally transferred to industrially forged CP-Ti and Ti5Al2.5Sn. TEM and neutron diffraction confirmed the onset of Ti3Al formation from Al concentrations above 7at.% (4wt%), but no ordering of Zr or Sn atoms was found after solution treatments. The evolution of lattice strain and lattice reorientation due to twinning with increasing compressive strain was captured by in-situ experiments under neutron diffraction at Engin-X, ISIS. Post-mortem EBSD micro and macro texture mappings revealed that the twin fraction in Al reduces above a critical concentration of 7at.% (4wt%), which was enhanced with increasing ordering towards Ti3Al. Sn and Zr addition showed no significant effect on the overall twin fraction, but increased twin numbers with facilitated nucleation and impeded twin growth, which may be related to the SFE. Increasing slip planarity and a transition from prismatic slip towards basal slip with addition of Al was found with means of Digital image correlation (DIC). DIC also revealed intense prismatic slip in grains undergoing !"!! tension twinning and virtually barely any strain accumulation within a twin below 9% plastic strain, rationalised by much increased nanohardness in the twin in comparison to the parent. Nanoindentation also revealed that alloying with Al reduces the crystal anisotropy. Finally it is believed that ordering and the closely related transition of slip patterns lead to the reduction in twin activity, while c/a ratio, crystal anisotropy and SFE seem less important.
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Martins, Marcio Marques. "Influência de parâmetros moleculares em funções de correlação temporal na dinâmica de solvatação mecânica". reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2004. http://hdl.handle.net/10183/6896.
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No presente trabalho descrevemos nossos resultados relativos à investigação da dinâmica de solvatação mecânica por meio de simulações por dinâmica molecular, respeitando o regime da resposta linear, em sistemas-modelo de argônio líquido com um soluto monoatômico ou diatômico dissolvido. Estudamos sistematicamente a influência dos parâmetros moleculares dos solutos (tamanho, polarizabilidade) e da densidade frente a vários modelos de solvatação. Funções de Correlação Temporal da Energia de Solvatação foram calculadas com relação à correlações de n-corpos (n = 2; 3) distinguindo interações repulsivas e atrativas para ambos os sistemas líquidos. Também obtivemos segundas derivadas temporais dessas funções referindo-se à parcelas translacionais, rotacionais e roto-translacionais na solução do diatômico. Encontramos que funções de correlação temporal coletivas podem ser razoavelmente bem aproximadas por correlações binárias a densidades baixas e, a densidades altas, correlações ternárias tornam-se mais importantes produzindo um descorrelacionamento mais rápido das funções coletivas devido a efeitos de cancelamento parciais. As funções de correlação para interações repulsivas e atrativas exibem comportamentos dinâmicos independentes do modelo de solvatação devido a fatores de escalonamento linear que afetam apenas as amplitudes das dessas funções de correlação temporal. Em geral, os sistemas com grau de liberdade rotacional apresentam tempos de correlação mais curtos para a dinâmica coletiva e tempos de correlação mais longos para as funções binárias e ternárias. Finalmente, esse estudo mostra que os sistemas contendo o diatômico relaxam-se predominantemente por mecanismos translacionais binários em modelos de solvatação envolvendo alterações apenas na polarizabilidade do soluto, e por mecanismos rotacionais atrativos binários em modelos envolvendo alterações no comprimento de ligação.In the present work, we describe our results concerning our molecular dynamics investigation of the mechanical solvation dynamics within the linear response regime in model systems composed by liquid argon with a monoatomic or diatomic solute. The effect of molecular parameters (size, polarizability) and density has been elucidated for various solvation models. Time Correlation Functions for the solvation energy were calculated and separated into n-body (n = 2; 3) contributions distinguishing repulsive and attractive interactions in both liquid systems. In addition, we computed second time derivatives of these functions in order to describe translational, rotational, and roto-translational portions in the solutions containing the diatomics. We found that collective time correlation functions are well described by binary correlations at low liquid densities and, at high densities, ternary correlations become more important producing faster decaying collective time correlation functions due to partial cancellation effects. The repulsive and attractive time correlation functions exhibit a dynamic behavior that is independent on the solvation model due to linear scaling factors that only affect the absolute amplitudes of these functions. In general, the systems involving a rotational degree of freedom furnish smaller correlation times for the collective solvation dynamics, but stronger correlated two-body and three-body terms. Finally, this study shows that the solvation dynamics for the solution containing the diatomics relaxes predominatly by binary translational mechanisms when solvation models involving changes only in the polarizability parameter are considered. Binary attractive rotational mechanism become important in models with changes in the bond length.
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Shetty, Bhupesh. "Process pattern mining: identifying sources of assignable error using event logs". Diss., University of Iowa, 2018. https://ir.uiowa.edu/etd/6641.
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This thesis examines the problem of identifying patterns in process event logs that are correlated with binary events that are undetected until the end of the process. Specifically, we consider the task of identifying patterns in a machine shop manufacturing process that are correlated with product defect. We introduce a pattern mining algorithm based on Apriori to identify frequent patterns, and use binary correlation measures to identify patterns associated with elevated defect rate. We design a simulation model to generate synthetic datasets to test our algorithm. We compare the effectiveness of different correlation measures, target pattern complexities, and sample sizes with and without knowledge of the underlying process. We show that knowledge of the underlying process helps in identifying the pattern that is associated with defects. We also develop a decision support tool based on p-value simulation to help managers identify sources of error in real-life settings. Finally, we apply our method to real world data and extract useful information from the data to help plant managers make decisions related to investments and workforce planning.
This thesis also explores the problem of predicting the defect probability given an ordered list of events and its defect status. We develop a supervised learning model using the frequency of patterns deduced from the event log as the feature set. We discuss the challenges faced in this approach and conclude that random forest algorithm performs better than other methods. We apply this approach to a real world case study and discuss the applications in the machine shop.
Finally, the thesis explores the order-bidding process in the machine shop industry, and proposes an optimization-based model to maximize the profit of the machine shop. Through a case study example, we show the advantages of using the defect probability in the proposed optimization model to determine the machine-worker schedule to execute job orders in a machine shop.
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New, Nicholas James. "The binary phase only joint transform correlator". Thesis, University of Cambridge, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.620434.
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Musil, Petr. "Demonstrace metod snižování pravděpodobnosti chybného příjmu". Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2018. http://www.nusl.cz/ntk/nusl-377339.
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This thesis deals with the demonstration of bit error rate reduction techniques. In the theory section, different techniques of bit error rate reduction are presented, followed by the introduction of the communication channel and the communication system parameters. Each technique is simulated in Matlab Simulink environment using the additive white Gaussian noise channel model. The simulations are captured in waveform oscillograms of all the signal processing stages. The practical section of this thesis offers a functional laboratory solution demonstrating different ways of transmission: a direct-path signal, a path with a cross-correlation receiver and a path using matched filtering. The individual circuits are described in detail, including waveform oscillograms of the signal processing blocks for illustration. Furthermore, the practical section presents printed circuit boards designs, comprehensive documentation for production, measurement results and a sample laboratory protocol.
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Ruengvirayudh, Pornchanok. "A Monte Carlo Study of Parallel Analysis, Minimum Average Partial, Indicator Function, and Modified Average Roots for Determining the Number of Dimensions with Binary Variables in Test Data: Impact of Sample Size and Factor Structure". Ohio University / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou151516919677091.
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Butt, J. A. "Invariant binary phase only filters for Joint Transform Correlator". Thesis, University of Cambridge, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.597188.
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Many JTC systems are constructed with the use of ferroelectric liquid crystal (FLC) spatial light modulators (SLMs) as they provide fast two dimensional binary modulation of coherent light. Due to the binary nature of the FLC SLMs used in the JTC systems, any image addressed to the device need to have some form of thresholding. Carefully thresholding the grey scale input plane and the joint power spectrum (JPS) has significant effect on the quality of correlation peaks and zero order (DC) noise. A new thresholding technique to binarise the JPS has been developed and implemented optically. This algorithm selectivity enhances the desirable fringes in the JPS which provide correlation peaks of higher intensity. Zero order noise is further reduced when compared to existing thresholding techniques. Keeping in mind the architecture of the JTC and limitations of FLC SLMs, a new technique to design rotation and scale invariant binary phase only filters for the JTC architecture is presented. Filers design with this technique have limited dynamic range, higher discriminability among target and non-target objects, and convenience for implementation on FLC SLMs. Simulation and experiments shows excellent results of various rotation and scale invariant filters designed with this technique. A rotation invariant filter is needed for various machine vision applications of the JTC. By fixing the distance between the camera and the input object, the scale sensitivity of the correlator can be avoided. In contrast to the industrial machine vision applications scale factor is very important factor for the applications of the JTC systems in defence and security. A security system using a scale invariant JTC will be able to detect a target object well in advance and will provide more time to take a decision. The CCD camera used in the current JTC system has limited dynamic range. Since intensities are distributed over a huge range in the JPS, a large amount of information is lost at the point of capture, particularly in areas where CCD array is saturated. Due to the camera saturation it is difficult to make a direct comparison with the experimental results. Hence, replacing the current CCD camera with equivalent CMOS camera would minimise the amount of information lost and avoid the camera saturation.
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SOLASTIOUK, GALIVEL FRANCINE. "Equilibres liquide-vapeur des systemes propane-methanol et propane-methanol-dioxyde de carbone : mesures et representations". Paris, ENMP, 1988. http://www.theses.fr/1988ENMP0103.
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Thommana, John Vareed. "Simulation of a binary phase shift keyed receiver with an IF correlator for position location". Thesis, Virginia Tech, 1993. http://hdl.handle.net/10919/41982.
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Bohra, Lalit Kumar. "Analysis of Binary Fluid Heat and Mass Transfer in Ammonia-Water Absorption". Diss., Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/19780.
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An investigation of binary fluid heat and mass transfer in ammonia-water absorption was conducted. Experiments were conducted on a horizontal-tube falling-film absorber consisting of four columns of six 9.5 mm (3/8 in) nominal OD, 0.292 m (11.5 in) long tubes, installed in an absorption heat pump. Measurements were recorded at both system and local levels within the absorber for a wide range of operating conditions (nominally, desorber solution outlet concentrations of 5 - 40% for three nominal absorber pressures of 150, 345 and 500 kPa, for solution flow rates of 0.019 - 0.034 kg/s.). Local measurements were supplemented by high-speed, high-resolution visualization of the flow over the tube banks. Using the measurements and observations from videos, heat and mass transfer rates, heat and vapor mass transfer coefficients for each test condition were determined at the component and local levels.
For the range of experiments conducted, the overall film heat transfer coefficient varied from 923 to 2857 W/m2-K while the vapor and liquid mass transfer coefficients varied from 0.0026 to 0.25 m/s and from 5.51×10-6 to 3.31×10-5 m/s, respectively. Local measurements and insights from the video frames were used to obtain the contributions of falling-film and droplet modes to the total absorption rates. The local heat transfer coefficients varied from 78 to 6116 W/m2-K, while the local vapor and liquid mass transfer coefficients varied from -0.04 to 2.8 m/s and from -3.59×10-5 (indicating local desorption in some cases) to 8.96×10-5 m/s, respectively. The heat transfer coefficient was found to increase with solution Reynolds number, while the mass transfer coefficient was found to be primarily determined by the vapor and solution properties. Based on the observed trends, correlations were developed to predict heat and mass transfer coefficients valid for the range of experimental conditions tested. These correlations can be used to design horizontal tube falling-film absorbers for ammonia-water absorption systems.
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Caniparoli, Jean-Philippe. "Etude par resonance magnetique nucleaire des conformations et des interactions moleculaires dans les mesophases lyotropes : application a des problemes de solubilisation". Paris 6, 1988. http://www.theses.fr/1988PA066117.
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Etude par rmn, de l'ordre et de la dynamique moleculaire des phases lyotropes de systemes binaires agent de surface a double chaine/eau: parametres d'ordre eleves, probabilites conformationelles, temps de correlation des mouvements moleculaires tres anisotropes en fonction de la tete polaire (phosphate ou ammonium); faible influence de la longueur de la chaine. Etude de l'ordre et de la dynamique de petites molecules en solution dans le systeme dibutylphosphate de sodium/eau en phase lamellaire: influence importante du caractere hydrophile ou hydrophobe du solute. Localisation des solutes non complexants dans le cristal liquide d'apres la relaxation induite par un ion paramagnetique
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Mandray, Ariane. "Etude magnéto-optique de centres D- confinés dans des multi-puits quantiques GaAs/AlGaAs". Université Joseph Fourier (Grenoble), 1994. http://www.theses.fr/1994GRE10075.
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Le centre d#-, ou ion donneur negatif, est l'analogue en physique du solide de l'ion hydrogene negatif h#-. Il s'agit donc d'un systeme correle simple, avec seulement deux electrons. Les transitions magneto-optiques permettant l'etude des donneurs peu profonds (neutres ou charges negativement) dans les multi-puits gaas/algaas se situent dans la gamme de l'infra-rouge lointain. Notre appareillage experimental est essentiellement constitue d'un spectrometre a transformee de fourier, couple a un aimant supraconducteur ou resistif. Nous avons etudie le mecanisme de formation des centres d#- confines dans des multi-puits quantiques. Dans cette configuration, contrairement au materiau massif, les centres d#- sont formes par construction, ce qui permet leur etude a l'equilibre thermodynamique. L'importance de la geometrie de dopage est soulignee, et la possibilite de realiser un dopage d#- de puits quantiques est mise en evidence. Le spectre d'energie des centres d#- confines a ete etudie pour une large gamme de champs magnetiques (jusqu'a 20 t) et pour differentes largeurs de puits. Ces mesures permettent d'observer, outre la non-parabolicite de bande de gaas, les effets de correlation electronique augmentes par la baisse de dimensionalite. L'etude des centres d#- en presence de desordre d'alliage dans des puits de al-gaas met en evidence la possibilite de coexistence, dans ce type de systeme, de centres profonds et de centres peu profonds, tous deux charges negativement
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BOUCHET-BOUDET, NATHALIE. "Etude par diffraction de rayons x d'heterostructures epitaxiees a base des semi-conducteurs ii-vi cdte et znte". Université Joseph Fourier (Grenoble), 1996. http://www.theses.fr/1996GRE10153.
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Ce memoire traite de la caracterisation structurale par diffraction et reflectivite de rayons x d'heterostructures de semi-conducteurs ii-vi cdte et znte. Ce sont des heterostructures a fort desaccord parametrique, elaborees par epitaxie par jets moleculaires. Ce travail s'articule autour de deux themes: la caracterisation de reseaux de fils quantiques de znte, elabores par croissance par avancee de marche sur une surface vicinale de cdte (001), et l'etude des correlations verticales dans des superreseaux cd#0#. #8zn#0#. #2te/cdte et des superreseaux d'insertions fractionnaires de znte dans cdte. La croissance de systemes organises est un sujet tres actuel ; on espere ainsi elaborer des superreseaux de boites quantiques dans lesquelles les boites (ou les fils) presentent non seulement un ordre lateral, mais aussi un ordre vertical. L'insertion d'un plan fractionnaire de znte dans une matrice de cdte peut etre detectee en reflectivite de rayons x. La deformation parallele a l'axe de croissance, induite par le znte, est deduite du traitement de la reflectivite par un modele cinematique. La mesure de la periodicite laterale des fils deposes sur une surface vicinale est un sujet nouveau et tres delicat. Des mesures effectuees sur un echantillon desoriente de 1 et contenant un superreseau vertical ont donne la preuve de l'existence d'une periode laterale. Les longueurs de correlation dans le plan et hors du plan d'un superreseau de 2 couches de cd#0#. #8zn#0#. #2te et cdte de meme epaisseur sont deduites des mesures d'intensite diffuse en incidence rasante. Les calculs d'intensite diffuse sont faits dans l'approximation de born dite d'onde distordue. On montre enfin que des correlations verticales existent dans des superreseaux de boites et qu'il est possible de les mesurer en diffraction autour des pics de bragg. La correlation verticale est deux fois plus etendue dans un echantillon vicinal que dans un echantillon nominal
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Borges, Edilso Macedo Lopes. "Avaliação de Correlações e Equações de Estado para Determinação de Fatores de Compressibilidade de Gás Natural". Universidade do Estado do Rio de Janeiro, 2009. http://www.bdtd.uerj.br/tde_busca/arquivo.php?codArquivo=2574.
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O fator de compressibilidade (Z) de gás natural é utilizado em vários cálculos na engenharia de petróleo (avaliação de formações, perda de carga em tubulações, gradiente de pressão em poços de gás, cálculos de balanço de massa, medição de gás, compressão e processamento de gás). As fontes mais comuns de valores de Z são medições experimentais, caras e demoradas. Essa propriedade também é estimada por correlações empíricas, modelos baseados no princípio dos estados correspondentes ou equações de estado (EOS). Foram avaliadas as capacidades das EOS de Soave-Redlich-Kwong (SRK), Peng-Robinson (PR), Patel-Teja (PT), Patel-Teja-Valderrama (PTV), Schmidt-Wenzel (SW), Lawal-Lake-Silberberg (LLS) e AGA-8 para previsão desta propriedade em aproximadamente 2200 pontos de dados experimentais. Estes pontos foram divididos em quatro grupos: Grupo 1 (Presença de frações C7+, Grupo 2 (temperaturas inferiores a 258,15 K), Grupo 3 (pressões superiores a 10000 kPa) e Grupo 4 (pressões inferiores a 10000 kPa). Os cálculos utilizando as equações de estado sob diferentes esquemas de previsão de coeficientes binários de interação foram cuidadosamente investigados. Os resultados sugerem que a EOS AGA-8 apresenta os menores erros para pressões de até 70000 kPa. Entretanto, observou-se uma tendência de aumento nos desvios médios absolutos em função das concentrações de CO2 e H2S. As EOS PTV e a EOS SW são capazes de predizer o fator de compressibilidade (Z) com desvios médios absolutos entre os valores calculados e experimentais com precisão satisfatória para a maioria das aplicações, para uma variada faixa de temperatura e pressão. Este estudo também apresenta uma avaliação de 224 métodos de cálculo de Z onde foram utilizadas 8 correlações combinadas com 4 regras de mistura para estimativa de temperaturas e pressões pseudorreduzidas das amostras, junto com 7 métodos de caracterização das propriedades críticas da fração C7+, quando presente na composição do gás. Em função dos resultados são sugeridas, para diferentes tipos de sistemas, as melhores combinações de correlações com regras de mistura capazes de predizer fatores de compressibilidade (Z) com os menores erros absolutos médios relativosThe compressibility factor (Z-factor) of natural gases is necessary in many petroleum engineering calculations (evaluation of formation, pressure drop through a pipe, pressure gradient in gas wells, material balance calculations, gas metering, gas compression and processing). The most common sources of Z-factor values are experimental measurements, which are expensive and time consuming. This property is also estimated from empirical correlations, corresponding state models or equations of state (EOS) when experimental data is unavailable. Capabilities of Soave-Redlich-Kwong (SRK), Peng-Robinson (PR), Patel-Teja (PT), Patel-Teja-Valderrama (PTV), Schmidt-Wenzel (SW), Lawal-Lake-Silberberg (LLS) and AGA-8 to predict this property of 2200 data points under various schemes of binary interaction numbers are thoroughly investigated. This database was split on four groups: Group 1 (presence of hydrocarbon plus fraction - C7+), Group 2 (temperatures lower than 258.15 K), Group 3 (pressures higher than 10000 kPa) e Group 4 (pressures lower than 10000 kPa). The best results were obtained from EOS AGA-8 for pressures up to 70000 kPa. However, an increasing trend in average absolute deviations was observed as a function of CO2 e H2S concentrations. EOS PTV and EOS SW are capable to predict the compressibility factor (Z) with average absolute deviation between calculated and experimental values with satisfactory accuracy for most applications for a wide range of temperature and pressure. This study also presents an evaluation of 224 possible methods of calculating the gas compressibility factor, based on 8 correlations and corresponding state models, combined with 4 mixing rule that predict the pseudo-reduced pressure and temperatures of the mixture, that were combined with 7 methods of characterizing the plus fraction critical properties when present in the gas composition. Results suggest for different systems conditions, the best correlation and mixing rule combination capable of predicting Z-factor with the least average absolute relative error
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Bitseki, Penda Siméon Valère. "Inégalités de déviations, principe de déviations modérées et théorèmes limites pour des processus indexés par un arbre binaire et pour des modèles markoviens". Phd thesis, Université Blaise Pascal - Clermont-Ferrand II, 2012. http://tel.archives-ouvertes.fr/tel-00822136.
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Le contrôle explicite de la convergence des sommes convenablement normalisées de variables aléatoires, ainsi que l'étude du principe de déviations modérées associé à ces sommes constituent les thèmes centraux de cette thèse. Nous étudions principalement deux types de processus. Premièrement, nous nous intéressons aux processus indexés par un arbre binaire, aléatoire ou non. Ces processus ont été introduits dans la littérature afin d'étudier le mécanisme de la division cellulaire. Au chapitre 2, nous étudions les chaînes de Markov bifurcantes. Ces chaînes peuvent être vues comme une adaptation des chaînes de Markov "usuelles'' dans le cas où l'ensemble des indices à une structure binaire. Sous des hypothèses d'ergodicité géométrique uniforme et non-uniforme d'une chaîne de Markov induite, nous fournissons des inégalités de déviations et un principe de déviations modérées pour les chaînes de Markov bifurcantes. Au chapitre 3, nous nous intéressons aux processus bifurcants autorégressifs d'ordre p (). Ces processus sont une adaptation des processus autorégressifs linéaires d'ordre p dans le cas où l'ensemble des indices à une structure binaire. Nous donnons des inégalités de déviations, ainsi qu'un principe de déviations modérées pour les estimateurs des moindres carrés des paramètres "d'autorégression'' de ce modèle. Au chapitre 4, nous traitons des inégalités de déviations pour des chaînes de Markov bifurcantes sur un arbre de Galton-Watson. Ces chaînes sont une généralisation de la notion de chaînes de Markov bifurcantes au cas où l'ensemble des indices est un arbre de Galton-Watson binaire. Elles permettent dans le cas de la division cellulaire de prendre en compte la mort des cellules. Les hypothèses principales que nous faisons dans ce chapitre sont : l'ergodicité géométrique uniforme d'une chaîne de Markov induite et la non-extinction du processus de Galton-Watson associé. Au chapitre 5, nous nous intéressons aux modèles autorégressifs linéaires d'ordre 1 ayant des résidus corrélés. Plus particulièrement, nous nous concentrons sur la statistique de Durbin-Watson. La statistique de Durbin-Watson est à la base des tests de Durbin-Watson, qui permettent de détecter l'autocorrélation résiduelle dans des modèles autorégressifs d'ordre 1. Nous fournissons un principe de déviations modérées pour cette statistique. Les preuves du principe de déviations modérées des chapitres 2, 3 et 4 reposent essentiellement sur le principe de déviations modérées des martingales. Les inégalités de déviations sont établies principalement grâce à l'inégalité d'Azuma-Bennet-Hoeffding et l'utilisation de la structure binaire des processus. Le chapitre 5 est né de l'importance qu'a l'ergodicité explicite des chaînes de Markov au chapitre 3. L'ergodicité géométrique explicite des processus de Markov à temps discret et continu ayant été très bien étudiée dans la littérature, nous nous sommes penchés sur l'ergodicité sous-exponentielle des processus de Markov à temps continu. Nous fournissons alors des taux explicites pour la convergence sous exponentielle d'un processus de Markov à temps continu vers sa mesure de probabilité d'équilibre. Les hypothèses principales que nous utilisons sont : l'existence d'une fonction de Lyapunov et d'une condition de minoration. Les preuves reposent en grande partie sur la construction du couplage et le contrôle explicite de la queue du temps de couplage.
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Yu, Nam Yul. "On Periodic Correlation of Binary Sequences". Thesis, 2007. http://hdl.handle.net/10012/2634.
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A (periodic) correlation function is an important measure to evaluate the effectiveness of pseudorandom sequences. In practice, the sequences are required to have the impulse-like autocorrelation function. Also, crosscorrelation magnitudes of the distinct sequences must be as low as possible. Theoretically, the correlation of sequences has a strong connection with problems of algebraic coding and combinatorics. Namely, the correlation distribution of sequences is related to the weight distribution of codewords in algebraic codes. Furthermore, binary sequences with ideal two-level autocorrelation are equivalent to cyclic Hadamard difference sets in combinatorics. Therefore, a good knowledge of coding theory and combinatorics is helpful for a study of sequences with low correlation. In this thesis, the correlation of binary sequences is studied by the aid of fruitful results of coding theory and combinatorics. From this study, some interesting properties are presented on the correlation of binary sequences, and several new binary sequences with low correlation are discovered. The outline of thesis is as follows. First of all, crosscorrelation properties of binary sequences with ideal two-level autocorrelation are studied. The 3- and 5-valued crosscorrelation properties of several classes of binary sequences with ideal two-level autocorrelation are completely determined by either theoretical proofs or conjectures. Second, new binary sequences of period of a multiple of 4 are proposed by making use of the interleaved structure of sequences. The sequences have three-valued out-of-phase autocorrelation, i.e., {0, -4, +4}, which is optimal with respect to autocorrelation magnitude. Third, a new binary sequence family with low correlation and a large family size is proposed and its asymptotic optimality is examined. With respect to maximum correlation, a family size, and a linear complexity, the sequence family is competitive among all known binary sequence families. Finally, the construction of quadratic bent functions of a special polynomial form is presented by providing necessary and sufficient conditions on the coefficients of the polynomial. The resulting quadratic bent functions can be employed for the linear feedback shift register (LFSR) implementation of a family of bent sequences, which is a potential candidate for future code-division multiple access (CDMA) system.
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"On specifying correlation matrices for binary data". SFB Adaptive Information Systems and Modelling in Economics and Management Science, 1999. http://epub.wu-wien.ac.at/dyn/dl/wp/epub-wu-01_1b3.
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Holland, Ricky R. "Refractive turbulence profiles via binary source intensity scintillation correlation". Thesis, 1988. http://hdl.handle.net/10945/23376.
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Chang, Wei-Wen y 張暐文. "The Efficiency of Intraclass Correlation Estimating for Binary Data". Thesis, 2005. http://ndltd.ncl.edu.tw/handle/41647128621093505484.
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碩士國立中興大學
農藝學系
93
Binary data occur frequently in research of epidemiology, sociology, biology and so forth, such as studies of familial diseases and repeated measurement studies and like versa. In these conditions, there is a correlation between these observations. The intraclass correlation coefficient (ICC) is a quantitative measure of the resemblance among observations within clusters. At least 20 different point estimators of the ICC have been proposed in various areas of application. However, techniques for binary data have been less developed. And the efficiency and application of these techniques are differ from each other. The main purposes of this research aimed to estimate the intraclass correlation coefficient and to evaluate the efficiency of the three ICC methods for binary data proposed by Ridout et al. (1999). Base on common correlation model, computer simulation is applied to compare these three methods in this research. All the simulations in this article are implemented by using the program language of Visual Basic. According to the changes of the three parameters (i.e. intraclass correlation coefficient ρ, the probability of success π, and number of clusters k), the performances of each method are discussed under different parameter combinations. Simulation results indicated that the coverage of confidence interval obtained from ANOVA method performed well only when ρ is small. However, it is not stable under other parameter combinations. On the other hand, the coverage of confidence interval based on the Pearson and the FC estimates for ρ, showed highly stable under any combinations of parameter. In general, the coverage levels of the three methods are low when k is small. Even k is increasing, the coverage rates perform not ideally when the ρ is extreme (ρ is close to 0 or 1). Thus, research requires these three methods to apply in certain particular situations, such as sample size is small or extremely high or low intraclass correlation, the correlation coefficients and confidence intervals estimated by these methods should not be credible.
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李柏齡. "the layout analysis of binary document iamge by corss-correlation". Thesis, 2009. http://ndltd.ncl.edu.tw/handle/2b6d6v.
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Biondi, Giulio. "Evolutionary Discovery of Binary-Similarity Correlations for Link Prediction". Doctoral thesis, 2021. http://hdl.handle.net/2158/1261921.
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A relevant topic in complex networks research is modelling network links dynamics. Link Prediction techniques aim to assess the likelihood that a potential link will form between a pair of not connected networks nodes. The ability to forecast links formation is valuable in many application areas involving complex networks, ranging from e-commerce to biology, to social networks.
Binary correlation indices are crucial in Link Prediction to assess nodes similarity for link formation.
Formulating appropriate binary correlations is a time-consuming interactive and mostly empirical process, where researchers progressively evaluate and modify them to adjust their prediction ability to the specific characteristics of the network domain.
Modelling the process of discovering optimal correlation indices is, therefore, a critical issue.
This work proposes a novel approach based on evolutionary optimisation to determine new correlations, best suited to the domain, by the evolution of meta-correlation indices.
The introduced original concept of meta-correlation index entails a parametric formula that represents classes of binary similarity indices subsuming existing ones, and generating, for appropriate parameters assignment, a particular instance of binary correlation. The proposed evolutionary framework uses the Differential Evolution algorithm for numerical optimisation.
Experiments held on a variety of binary similarity measures and real network domains show that correlations, evolved from meta-correlations in the proposed framework, perform better than most previously binary correlation indices on the same domains, effectively exploring the correlation space and exploiting self-adaptive capabilities.
The value of the proposed approach, obtaining satisfactory results in binary correlation discovery and adaptation to a specific domain for link prediction, is also represented by the potential extension and application to other research areas involving experimental evaluation of correlations indices.
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Tsai, Hsin-Ni y 蔡忻妮. "Approximate Bayesian approaches for assessing intraclass correlation coefficients in dependent binary data". Thesis, 2011. http://ndltd.ncl.edu.tw/handle/07158093177833882557.
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碩士國立彰化師範大學
統計資訊研究所
99
Medical data in clinical studies are commonly carried out in clustered settings, where the subjects are correlated within clusters. When observations approximately follow a normal distribution, the intraclass correlation coefficient (ICC) is frequently used to assess the similarity within clusters with respect to the particular biological or environmental characteristics. However, for correlated binary data, it is difficult to obtain directly the ICCs by the definition of the proportion of the total variation explained by variation between clusters. In this article, we propose two approximate Bayesian statistical approaches, approximate Taylor Bayesian and empirical Bayesian approaches, to estimate ICCs in multilevel logit models for dependent binary data. To compare with a frequentist approach, we make a comparison between the approximate Taylor Bayesian, the empirical Bayesian, and the ANOVA approaches in simulation studies. The results of comparison studies reveal that the proposed approximate Bayesian approaches provide reliable and stable approaches in estimating ICCs, and parameters of fixed effects and variance components simultaneously. Furthermore, the results indicate that the approximate Bayesian approaches are robust in model misspecification.
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Bruwer, Christian S. "Correlation attacks on stream ciphers using convolutional codes". Diss., 2005. http://hdl.handle.net/2263/24740.
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This dissertation investigates four methods for attacking stream ciphers that are based on nonlinear combining generators: -- Two exhaustive-search correlation attacks, based on the binary derivative and the Lempel-Ziv complexity measure. -- A fast-correlation attack utilizing the Viterbi algorithm -- A decimation attack, that can be combined with any of the above three attacks. These are ciphertext-only attacks that exploit the correlation that occurs between the ciphertext and an internal linear feedback shift-register (LFSR) of a stream cipher. This leads to a so-called divide and conquer attack that is able to reconstruct the secret initial states of all the internal LFSRs within the stream cipher. The binary derivative attack and the Lempel-Ziv attack apply an exhaustive search to find the secret key that is used to initialize the LFSRs. The binary derivative and the Lempel-Ziv complexity measures are used to discriminate between correct and incorrect solutions, in order to identify the secret key. Both attacks are ideal for implementation on parallel processors. Experimental results show that the Lempel-Ziv correlation attack gives successful results for correlation levels of p = 0.482, requiring approximately 62000 ciphertext bits. And the binary derivative attack is successful for correlation levels of p = 0.47, using approximately 24500 ciphertext bits. The fast-correlation attack, utilizing the Viterbi algorithm, applies principles from convolutional coding theory, to identify an embedded low-rate convolutional code in the pn-sequence that is generated by an internal LFSR. The embedded convolutional code can then be decoded with a low complexity Viterbi algorithm. The algorithm operates in two phases: In the first phase a set of suitable parity check equations is found, based on the feedback taps of the LFSR, which has to be done once only once for a targeted system. In the second phase these parity check equations are utilized in a Viterbi decoding algorithm to recover the transmitted pn-sequence, thereby obtaining the secret initial state of the LFSR. Simulation results for a 19-bit LFSR show that this attack can recover the secret key for correlation levels of p = 0.485, requiring an average of only 153,448 ciphertext bits. All three attacks investigated in this dissertation are capable of attacking LFSRs with a length of approximately 40 bits. However, these attacks can be extended to attack much longer LFSRs by making use of a decimation attack. The decimation attack is able to reduce (decimate) the size of a targeted LFSR, and can be combined with any of the three above correlation attacks, to attack LFSRs with a length much longer than 40 bits.Dissertation (MEng (Electronic Engineering))--University of Pretoria, 2007.
Electrical, Electronic and Computer Engineering
unrestricted
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Yu, Chia-Chun y 余嘉淳. "The effects of intraclass correlation coefficients on regression analyses with clustered binary data". Thesis, 2014. http://ndltd.ncl.edu.tw/handle/99909520707197232422.
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碩士國立陽明大學
公共衛生研究所
102
Binary clustered data are often encountered in public health and clinical research. Difference analyses methods can obtain different results of parameter estimates. Intraclass correlation coefficient (ICC) usually is used to quantify the degree of relation in outcomes within cluster. The ICCs are not necessarily substantial in longitudinal or clustered data after adjusting for related variables. The effects of ICC, prevalence of outcome variable, number of clusters and cluster size on parameter estimates remain to be explored. The present study carried out a simulation study with different scenarios with different ICC, prevalences of outcome, numbers of clusters and clusters size for both binary and continuous predictors . The simulations considered four values of ICC: 0, 0.1, 0.3, 0.5, four prevalence of outcome: 0.3, 0.1, 0.05, 0.01, conditional on the total number of observations 1000 with five combinations of the number of clusters (m) and cluster size (n): (m,n)=(500,2), (200,5), (100,10), (10,100), (5,200), independent variables for continue and dichotomy with multicollinearity or not. Based on the context of logistic regression models, the methods of parameter estimation included standard method of maximum-likelihood which assume data were independent, generalized estimating equation (GEE) that using exchangeable correlation coefficient and odds ratio (alternate logistic regression), and generalized mixed linear models (GLMMs) using adaptive guass-hermite quadrature (GLMM_FL) and pseudo-likelihood approximation (GLMM_PL). The results of simulation showed that the prevalence of outcome did not have substantial effect on parameter estimates, on the other hand, the estimates were different with different ICC. When the ICC was close to zero(ICC=0), the performance of standard logistic regression is the best, GEE was second best when m>n and GLMMs in general obtain invalid estimates of parameter. When ICC was low (ICC=0.1) and the number of clusters was bigger than cluster size (m>n), the estimates by standard logistic regression, GEE and GLMMs_FL were valid. When ICC is low (ICC=0.1) and the number of clusters was smaller than cluster size (m
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"Three Essays on Correlated Binary Outcomes: Detection and Appropriate Models". Doctoral diss., 2018. http://hdl.handle.net/2286/R.I.49005.
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abstract: Correlation is common in many types of data, including those collected through longitudinal studies or in a hierarchical structure. In the case of clustering, or repeated measurements, there is inherent correlation between observations within the same group, or between observations obtained on the same subject. Longitudinal studies also introduce association between the covariates and the outcomes across time. When multiple outcomes are of interest, association may exist between the various models. These correlations can lead to issues in model fitting and inference if not properly accounted for. This dissertation presents three papers discussing appropriate methods to properly consider different types of association. The first paper introduces an ANOVA based measure of intraclass correlation for three level hierarchical data with binary outcomes, and corresponding properties. This measure is useful for evaluating when the correlation due to clustering warrants a more complex model. This measure is used to investigate AIDS knowledge in a clustered study conducted in Bangladesh. The second paper develops the Partitioned generalized method of moments (Partitioned GMM) model for longitudinal studies. This model utilizes valid moment conditions to separately estimate the varying effects of each time-dependent covariate on the outcome over time using multiple coefficients. The model is fit to data from the National Longitudinal Study of Adolescent to Adult Health (Add Health) to investigate risk factors of childhood obesity. In the third paper, the Partitioned GMM model is extended to jointly estimate regression models for multiple outcomes of interest. Thus, this approach takes into account both the correlation between the multivariate outcomes, as well as the correlation due to time-dependency in longitudinal studies. The model utilizes an expanded weight matrix and objective function composed of valid moment conditions to simultaneously estimate optimal regression coefficients. This approach is applied to Add Health data to simultaneously study drivers of outcomes including smoking, social alcohol usage, and obesity in children.Dissertation/Thesis
Doctoral Dissertation Statistics 2018
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Chun, Chuang-Hui y 莊惠鈞. "A binary classification procedure based on the correlation with response variable and principal components". Thesis, 2018. http://ndltd.ncl.edu.tw/handle/773cha.
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碩士國立臺灣科技大學
資訊管理系
106
Binary classification method predicts the class of an object based on the associated feature vector. The main logic behind the classification is to regress the feature vector on the class variable. Due to the high correlation between feature variables, we apply principal component analysis to obtain the uncorrelated transformed features to mitigate the multicollinearity problem.For maintaining the simplicity and flexibility of modeling the relationship between the feature vector and the class variable, we propose to predict the class of an object based on an integrated feature which is the linear combination of the features and the powers of each individual feature.The weights on the original features and their powers, and the corresponding classification threshold are determined by the genetic algorithm to maximize the classification accuracy based on the training dataset.To speed up the convergence rate of the genetic algorithm, the solution obtained from the linear discrimination analysis is used as the starting point of the genetic algorithm.We apply the proposed procedure on the benchmark datasets, and experimental results demonstrate the effectiveness of our algorithm.
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Wu, Min-Je y 吳旻哲. "Phase Correlation and Binary Threshold Register for Alignment and Correction of Multifunctional Scanning Microscope Images Obtained Using Different Scanning Methods". Thesis, 2016. http://ndltd.ncl.edu.tw/handle/3wk933.
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碩士國立交通大學
照明與能源光電研究所
105
We construct a multifunctional scanning microscope system. There are two scanning methods: One scans by moving a nanopositioning stage, and another by swaying galvanometer mirrors. Because of the optical path difference of two scanning method, there are differences in translation, rotation, and scaling between two images. In order to make the multifunctional scanning microscope system practically useful, we developed image registration technique to accurately calibrate the images obtained using the two scanning methods. Phase correlation cannot be estimated by images having translation, rotation, and scaling differences at the same time. We first use threshold binary image processing to increase accuracy. Then, we overlap the feature points of two images so that the feature points of the nanopositioning stage image could be viewed as the reference rotational axis. The translation, rotation, and scaling parameters are found by phase correlation. Five sets of experiments are carried out to verify that this method can correctly register the relationship of images that are obtained using different scanning methods.
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Song, Chang Zhe y 宋昌哲. "Motion compensation considering global motion based on binary correlator". Thesis, 1994. http://ndltd.ncl.edu.tw/handle/94554619053182412480.
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Kuo, Chih-Lang y 郭智郎. "Binary Pattern Recognition by Incoherent Optical Correlator with Max-Min Algorithm". Thesis, 1997. http://ndltd.ncl.edu.tw/handle/15462009365019212605.
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碩士中華大學
電機工程研究所
85
An incoherent optical correlator is used for pattern recognition in this thesis. A practical algorithm with Max-Min has been proposed to create a reference pattern within the incoherent optical correlator, which is shown to be very effective for pattern recognition. An N reference patterns algorithm in which the reference patterns are set as the same as the images of the given N objects and the Max-Min algorithm in which the reference pattern is the special combination of the given N objects have been studied. Effects of transmittance of the LCD (Liquid Crystal Display) associated with the light source are also studied. Effects of diffraction of light, related to the common edge between the object and the reference pattern, are also verified to data. The results show that the adjustment is effective to match data between the simulation and that of the measurements.
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Banerjee, Saikat. "Hydrophobicity and Composition-Dependent Anomalies in Aqueous Binary Mixtures, along with some Contribution to Diffusion on Rugged Energy Landscape". Thesis, 2014. http://hdl.handle.net/2005/3025.
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I started writing this thesis not only to obtain a doctoral degree, but also to compile in a particular way all the work that I have done during this time. The articles published during these years can only give a short overview of my research task. I decided to give my own perspective of the things I have learned and the results I have obtained. Some sections are directly the published articles, but some other are not and contain a significant amount of unpublished data. Even in some cases the published plots have been modified / altered to provide more insight or to maintain consistency. Historical perspectives often provide a deep understanding of the problems and have been briefly discussed in some chapters.
This thesis contains theoretical and computer simulation studies to under-stand effects of spatial correlation on dynamics in several complex systems. Based on the different phenomena studied, the thesis has been divided into three major parts:
I. Pair hydrophobicity, composition-dependent anomalies and structural trans-formations in aqueous binary mixtures
II. Microscopic analysis of hydrophobic force law in a two dimensional (2D) water-like model system
III. Diffusion of a tagged particle on a rugged energy landscape with spatial correlations
The three parts have been further divided into ten chapters. In the following we provide part-wise and chapter-wise outline of the thesis.
Part I consists of six chapters, where we focus on several important aqueous binary mixtures of amphiphilic molecules. To start with, Chapter 1 provides an introduction to non-ideality often encountered in aqueous binary mixtures. Here we briefly discuss the existing ideas of structural transformations associated with solvation of a foreign molecule in water, with particular emphasis on the classic “iceberg” model. Over the last decade, several investigations, especially neutron scattering and diffraction experiments, have questioned the validity of existing theories and have given rise to an alternate molecular picture involving micro aggregation of amphiphilic co-solvents in their aqueous binary mixtures. Such microheterogeneity was also supported by other experiments and simulations.
In Chapter 2, we present our calculation of the separation dependence of potential of mean force (PMF) between two methane molecules in water-dimethyl sulfoxide (DMSO) mixture, using constrained molecular dynamics simulation. It helps us to understand the composition-dependence of pair hydrophobicity in this binary solvent. We find that pair hydrophobicity in the medium is surprisingly enhanced at DMSO mole fraction xDMSO ≈ 0.15, which explains several anomalous properties of this binary mixture – including the age-old mystery of DMSO being a protein stabilizer at lower concentration and protein destabilizer at higher concentration.
Chapter 3 starts with discussion of non-monotonic composition dependence of several other properties in water-DMSO binary mixture, like diffusion coefficient, local composition fluctuation and fluctuations in total dipole moment of the system. All these properties exhibit weak to strong anomalies at low solute concentration. We attempt to provide a physical interpretation of such anomalies. Previous analyses often suggested occurrence of a “structural transformation” (or, microheterogeneity) in aqueous binary mixtures of amphiphilic molecules. We show that this structural transformation can be characterized and better understood under the purview of percolation theory. We define the self-aggregates of DMSO as clusters. Analysis of fractal dimension and cluster size distribution with reference to corresponding “universal” scaling exponents, combined with calculation of weight-averaged fraction of largest cluster and cluster size weight average, reveal a percolation transition of the clusters of DMSO in the anomalous concentration range. The percolation threshold appears at xDMSO ≈ 0.15. The molecular picture suggests that DMSO molecules form segregated islands or micro-aggregates at concentrations below the percolation threshold. Close to the critical concentration, DMSO molecules start forming a spanning cluster which gives rise to a bi-continuous phase (of water-rich region and DMSO-rich region) beyond the threshold of xDMSO ≈ 0.15. This percolation transition might be responsible for composition-dependent anomalies of the binary mixture in this low concentration regime.
Similar phenomenon is observed for another amphiphilic molecule – ethanol, as discussed in Chapter 4. We again find composition dependent anomalies in several thermophysical properties, such as local composition fluctuation, radial distribution function of ethyl groups and self-diffusion co-efficient of ethanol. Earlier experiments often suggested distinct structural regimes in water-ethanol mixture at different concentrations. Using the statistical mechanical techniques introduced in the previous chapter, we show that ethanol clusters undergo a percolation transition in the anomalous concentration range. Despite the lack of a precise determination of the percolation threshold, estimate lies in the ethanol mole fraction range xEtOH ≈ 0.075 - 0.10. This difficulty is probably due to transient nature of the clusters (as will be discussed in Chapter 6) and finite size of the system. The scaling of ethanol cluster size distribution and the fractal behavior of ethanol clusters, however, conclusively demonstrate their “spanning” nature.
To develop a unified understanding, we further study the composition-dependent anomalies and structural transformations in another amphiphilic molecule, tertiary butyl alcohol (TBA) in Chapter 5. Similar to the above-mentioned aqueous binary mixtures of DMSO and ethanol, we demonstrate here that the anomalies occur due to local structural changes involving self-aggregation of TBA molecules and percolation transition of TBA clusters at xTBA ≈ 0.05. At this percolation threshold, we observe a lambda-type divergence in the fluctuation of the size of the largest TBA cluster, reminiscent of a critical point. Interestingly, water molecules themselves exhibit a reverse percolation transition at higher TBA concentration ≈ 0.45, where large spanning water clusters now break-up into small clusters. This is accompanied by significant divergence of the fluctuations in the size of the largest water cluster. This second transition gives rise to another set of anomalies around.
We conclude this part of the thesis with Chapter 6, where we introduce a novel method for understanding the stability of fluctuating clusters of DMSO, ethanol and TBA in their respective aqueous binary mixtures. We find that TBA clusters are the most stable, whereas ethanol clusters are the most transient among the three representative amphiphilic co-solvents. This correlates well with the amplitude of anomalies observed in these three binary mixtures.
Part II deals with the topic of hydrophobic force law in water. In the introductory Chapter 7 of this part, we briefly discuss the concept of hydrophobicity which is believed to be of importance in understanding / explaining the initial processes involved in protein folding. We also discuss the experimental observations of Israelachvili (on the force between hydrophobic plates) and the empirical hydrophobic force law. We briefly touch upon the theoretical back-ground, including Lum-Chandler-Weeks theory. We conclude this chapter with a brief account of relevant and important in silico studies so far.
In Chapter 8, we present our studies on Mercedes-Benz (MB) model – a two dimensional model system where circular disks interact with an anisotropic potential. This model was introduced by Ben-Naim and was later parametrized by Dill and co-workers to reproduce many of the anomalous properties of water.
Using molecular dynamics simulation, we show that hydrophobic force law is indeed observed in MB model, with a correlation length of ξ=3.79. The simplicity of the model enables us to unravel the underlying physics that leads to this long range force between hydrophobic plates. In accordance with Lum-Chandler-Weeks theory, density fluctuation of MB particles (leading to cavitation) between the hydrophobic rods is clearly distinguishable – but it is not sufficiently long ranged, with density correlation extending only up to ζ=2.45. We find that relative orientation of MB molecules plays an important role in the origin of the hydrophobic force in long range. We define appropriate order parameters to capture the role of orientation, and briefly discuss a plausible approach of an orientation-dependent theory to explain this phenomenon.
Part III consists of two chapters and focuses on the diffusion of a Brownian particle on a Gaussian random energy landscape. We articulate the rich history of the problem in the introductory Chapter 9. Despite broad applicability and historical importance of the problem, we have little knowledge about the effect of ruggedness on diffusion at a quantitative level. Every study seems to use the expression of Zwanzig [Proc. Natl. Acad. U.S.A, 85, 2029 (1988)] who derived the effective diffusion coefficient, Deff =D0 exp (-β2ε2 )for a Gaussian random surface with variance ε, but validity of the same has never been tested rigorously.
In Chapter 10, we introduce two models of Gaussian random energy surface – a discrete lattice and a continuous field. Using computer simulation and theoretical analyses, we explore many different aspects of the diffusion process. We show that the elegant expression of Zwanzig can be reproduced ex-actly by Rosenfeld diffusion-entropy scaling relationship. Our simulations show that Zwanzig’s expression overestimates diffusion in the uncorrelated Gaussian random lattice – differing even by more than an order of magnitude at moderately high ruggedness (ε>3.0). The disparity originates from the presence of “three-site traps” (TST) on the landscape – which are formed by deep minima flanked by high barriers on either side. Using mean first passage time (MFPT) formalism, we derive an expression for the effective diffusion coefficient, Deff =D0 exp ( -β2ε2)[1 +erf (βε/2)]−1 in the presence of TSTs. This modified expression reproduces the simulation results accurately. Further, in presence of spatial correlation we derive a general expression, which reduces to Zwanzig’s form in the limit of infinite spatial correlation and to the above-mentioned equation in absence of correlation. The Gaussian random field has an inherent spatial correlation. Diffusion coefficient obtained from the Gaussian field – both by simulations and analytical methods – establish the effect of spatial correlation on random walk. We make special note of the fact that presence of TSTs at large ruggedness gives rise to an apparent breakdown of ergodicity of the type often encountered in glassy liquids. We characterize the same using non-Gaussian order parameter, and show that this “breakdown” scales with ruggedness following an asymptotic power law.
We have discussed the scope of future work at the end of each chapter when-ever appropriate.