Dissertations / Theses on the topic 'Data lingo'

Diploma thesis deals with the evaluation of the efficiency using DEA models focusing on the use of dedicated software tools. There are four chapters in the thesis where different approaches to efficiency are briefly presented. The method of data envelopment analysis (DEA) with its modifications is described in detail -- basic models, CCR, BCC and additive model. The main part of the work is presented in the second part of this thesis where I describe how to work with each program and summarize its advantages and disadvantages. The last chapter applies prior knowledge on real situation -- the evaluation of the efficiency of the regional police stations in the Czech Republic.

This thesis presents the results of the STAMPAS all-sky search for long transient gravitational waves in the 2005-2007 LIGO-Virgo data. Gravitational waves are perturbations of the space-time metric. The Virgo and LIGO experiments are designed to detect such waves. They are Michelson interferometers with 3 km and 4 km long arms, whose light output is altered during the passage of a gravitational wave.Until very recently, transient gravitational wave search pipelines were focused on short transients, lasting less than 1 second, and on binary coalescence signals. STAMPAS is one of the very first pipelines entirely dedicated to the search of long transient gravitational wave signals, lasting from 1s to O(100s).These signals originate, among other sources, from instabilities in protoneutron stars as a result of their violent birth. The standing accretion shock instability in core collapse supernovae or instabilities in accretion disks are also possible mechanisms for gravitational wave long transients. Eccentric black hole binary coalescences are also expected to emit powerful gravitational waves for several seconds before the final plunge.STAMPAS is based on the correlation of data from two interferometers. Time-frequency maps of the data are extracted, and significant pixels are clustered to form triggers. No assumption on the direction, the time or the form of the signals is made.The first STAMPAS search has been performed on the data from the two LIGO detectors, between 2005 and 2007. After a rigorous trigger selection, the analysis revealed that their rate is close to Gaussian noise expectation, which is a significant achievement. No gravitational wave candidate has been detected, and upper limits on the astrophysical rates of several models of accretion disk instability sources and eccentric black holes binary coalescences have been set. The STAMPAS pipeline demonstrated its capabilities to search for any long transient gravitational wave signals during the advanced detector era.Keywords: Gravitational waves, Interferometry, Long transients, Signal Processing, Accretion Disk Instabilities, Eccentric Black Hole Binaries.

Cette thèse présente les résultats de la recherche de signaux d’ondes gravitationnelles produits par des cordes cosmiques dans les données des deux premières périodes d’observation des détecteurs de seconde génération Advanced LIGO et Advanced Virgo. Les cordes cosmiques sont des défauts topologiques unidimensionnels créés dans l’Univers primordial. Ces objets sont prédits par de nombreux modèles de physiques de très hautes énergies. La forme attendue du signal d’ondes gravitationnelles émis par des cordes cosmiques est prédite par la théorie. On utilise une technique de filtrage optimal pour rechercher la présence d’un signal dans les données des détecteurs Advanced LIGO et Advanced Virgo. Cette technique est optimale si le bruit du détecteur est gaussien et stationnaire, ce qui n’est pas le cas. Une partie essentielle du travail de thèse a consisté à comprendre et réduire le bruit de fond de l’analyse. Ce travail sur la qualité des données a permis d’augmenter la sensibilité de la recherche. De plus on montre que la recherche de signaux transitoires d‘ondes gravitationnelles produits par des cordes cosmiques est limitée par la présence d‘une famille particulière de bruits qui miment le signal prédit pour les cordes cosmiques. En l'absence de détection, nous avons placé des limites sur les paramètres qui caractérisent un réseau de cordes cosmiques pour différents modèles théoriques, afin de préciser les conditions d’existence de ces dernières
This thesis shows the results of the search for gravitational-wave signals produced by cosmic strings using the data from the first two observation runs of the second generation detectors Advanced LIGO and Advanced Virgo. Cosmic strings are one-dimensional topological defects created in the primordial Universe. These objects are predicted by many models of very high energy physics. The gravitationalwave signal emitted by cosmic strings is predicted by theory. A matched-filter analysis is used to search for the presence of a signal in Advanced LIGO and Advanced Virgo data. This technique is optimal if the detector noise is Gaussian and stationary, which is not the case. An essential part of the thesis work was to understand and reduce the background noise analysis. This work on data quality has increased the sensitivity of the search. Furthermore, we have shown that the search for transient signals of gravitational waves produced by cosmic strings is limited by the presence of a particular family of noises that mimic the predicted signal for cosmic strings. In the absence of detection, we have placed constraints on the parameters which characterize a cosmic string network for different theoretical models, in order to specify the conditions of their existence

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 2005.
Includes bibliographical references (p. 279-293).
The network of detectors comprising the Laser Interferometer Gravitational-wave Observatory (LIGO) are among a new generation of detectors that seek to make the first direct observation of gravitational waves. While providing strong support for the General Theory of Relativity, such observations will also permit new tests of physical theory in regions of strong space-time curvature and high matter-energy density. However, the observed signals are expected to occur near the limit of detector sensitivity. The problem of identifying such small signals is the primary focus of this work. This work presents a novel method for the identification of astrophysically unmodeled bursts of gravitational radiation in data from networks of interferometric detectors. The method is based on the Q transform, a multiresolution time-frequency transform that efficiently targets waveforms within a finite region of time, frequency, and Q space. The method is also based on a modification of linear prediction that greatly simplifies the resulting statistical analysis by whitening interferometric detector data prior to Q transform analysis. Together, these techniques form the basis of a complete analysis pipeline that is equivalent to a template-based matched filter search for minimum uncertainty waveforms in the whitened data stream. This method is then applied to search for gravitational-wave bursts with duration less than 1 second and frequency content between 64 and 1024 Hz in coincident data from two detectors during second LIGO science run. Although no gravitational-wave bursts are identified,
(cont.) upper bounds are reported for the rate of gravitational-wave bursts as a function of signal strength for isotropic and galactic populations of sources with both abstract and astrophysically motivated waveform. The results indicate a maximum of 0.09 events per day at the 90% confidence level for bursts with characteristic strain amplitude in excess of 10-20 to 10-19 strain Hz-l/2 depending on waveform. A comparison with previous searches demonstrates that this search is one of the most sensitive to date for gravitational-wave bursts of unknown waveform, and is inconsistent with recent indications for an statistical excess of events by the ROG collaboration at above the 99% confidence level.
by Shourov Keith Chatterji.
Ph.D.

Cette thèse présente les résultats de la recherche de signaux impulsionnels d'ondes gravitationnelles associés aux sursauts gamma dans les données 2009-2010 des interféromètres LIGO-Virgo. L'étude approfondie des mécanismesd'émission d'ondes gravitationnelles par les progéniteurs de sursauts gamma, ainsi que des mécanismes d'émission de rayons gamma eux-mêmes, permet de déterminer les caractéristiques essentielles du signal à détecter : polarisation, délai temporel, etc ... Cette connaissance de l'émission conjointe permet alors de construire une méthode d'analyse qui inclut les a priori astrophysiques. Cette méthode est de plus robuste vis-à-vis des bruits transitoires présents dans les données. L'absence de détection nous permet de placer des limites observationnelles inédites sur la population des sursauts gamma.

Thesis (Ph. D.)--University of Oregon, 2006.
Typescript. Includes vita and abstract. Includes bibliographical references (leaves 113-116). Also available for download via the World Wide Web; free to University of Oregon users.

Thesis: S.B., Massachusetts Institute of Technology, Department of Physics, 2016.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 45-47).
Introduction: Core collapse supernova are one of the most intriguing astrophysical phenomena. The dying stage of a supergiant star, they occur when the star collapses into a protoneutron star, causing a shock wave and a gamma ray burst. High energy neutrinos are released in this process and offer the possibility of detecting these elusive cataclysms. The number of neutrinos emitted is large but at best only a few will be detected. With a multi-messenger search, we can combine the neutrino signal with another clue to the presence of a supernova: gravitational waves. During the proto-neutron star stage, a fast-rotating star can produce gravitational waves via its asymmetric and rapidly shifting mass. By combining the signals from neutrinos and gravitational waves, we can attempt to detect supernova signals that are too faint to detect alone. Joint searches have already been attempted by several neutrino experiments with high-energy thresholds, including ANTARES and IceCube. This thesis explores the possibility of a joint search with a new set of neutrino data. KamLAND (Kamioka Liquid scintillator Anti-Neutrino Detector) is a large particle detector located in Kamioka, Japan. KamLAND is well-shielded, with an low (~ 1 MeV) energy threshold and has more than ten years of data to explore, making it a good candidate for a joint search. A recent search of KamLAND's data for clustered events indicative of supernova found no clear clusters. A new search is needed to identify single-neutrino events that may have originated in supernovae. A joint search will help KamLAND more carefully examine the possible sources of its single-neutrino events. The gravitational wave data comes from LIGO (Laser Interferometer Gravitational wave Observatory). Located in Hanford, WA and Livingston, LA, LIGO consists of two four-kilometer interferometer arms. Analysis of LIGO data from 2005 to 2010 did not produce any clear gravitational wave events, leading to a need for a more sensitive search. A multimessenger search in conjunction with KamLAND provides this opportunity. We can examine both KamLAND and LIGO's data in order to search for possible supernova signals observed by both experiments. Because a joint data-sharing agreement has not been reached between KamLAND and LIGO, this thesis looks at the potential of a joint analysis and the opportunity for such a study to produce promising results.
by Emmett E.E. Krupczak.
S.B.

This project examines the concept of computer hubs as a tool to increase technological inclusion in rural areas in lowincome countries. The viability of computer hubs as a concept was evaluated by looking at three factors among people living in such areas: acceptance of computers, the financial viability of computer hubs, and actual ease of use of computers. The study was conducted in Linga Linga, a small village located in the province of Morrumbene in southern Mozambique. Linga Linga is characterized by low technological inclusion and low income, which is typical for villages in rural areas in lowincome countries. Interviews, questionnaires, workshops and focus groups were conducted to examine the viability of computer hubs. The study indicates that the acceptance of computers, measured through attitude towards computers as well as perceived usefulness and perceived ease of use of computers, was sufficient for implementation. The study also concludes that the actual ease is sufficiently high, and even in cases where it is not due to a lack of previous experience with computers, the time it takes to learn is low. In addition, it was found that computer hubs are financially viable from a business perspective. In conclusion, computer hubs can be considered a viable approach to increase technological inclusion in rural areas in low-income countries.
Projektet undersöker konceptet computer hubs och hur det kan användas som ett verktyg för att öka teknologisk inkludering på landsbygden i låginkomstländer. Konceptet utvärderades genom att undersöka tre faktorer: användaracceptansen för datorer, computer hubs finansiella hållbarhet och den faktiska användbarheten hos datorer. Studien genomfördes i Linga Linga, en by belägen i provinsen Morrumbene i södra Moçambique. Linga Linga kännetecknas av låg teknologisk inkludering och invånare med låga eller inga inkomster. Intervjuer, frågeformulär, seminarium och fokusgrupper genomfördes för att undersöka konceptens genomförbarhet. Studien indikerar att användaracceptansen hos datorer, mätt genom attityd gentemot datorer såväl som upplevd användbarhet och upplevd användarvänlighet för datorer, var tillräcklig för implementering. Studien visar även att den faktiska användbarheten hos datorer är tillräckligt hög för implementering samt att den snabbt kan förbättras trots lite eller ingen tidigare erfarenhet av datorer. Studien visar även att en implementering av computer hubs är ekonomiskt hållbar ur ett affärsperspektiv. Sammanfattningsvis kan implementeringen av computer hubs som koncept betraktas som ett  hållbart tillvägagångssätt för att öka teknologisk inkludering i landsbygden i låginkomstländer.

L'objectif de ce travail est la détection conjointe d'ondes gravitationnelles et de neutrinos cosmique de haute énergie à travers une approche multi-messagers. Les astronomies "neutrinos" et "ondes gravitationnelles" sont encore en phase de développement, mais elles sont appelées à jouer un rôle fondamental dans le futur. En effet, ces "messagers" peuvent parcourir de grandes distances grâce à leur faible interaction avec la matière (contrairement aux photons qui, à haute énergie, sont rapidement absorbés), sans être affectés par les champs magnétiques (contrairement aux rayons cosmiques chargés). Ils peuvent également s' échapper de milieux denses et fournir des informations sur les processus qui ont lieu au coeur des sources astrophysique (les photons s' échappent des couches périphériques des objets célestes). En un mot, ces astronomies sont susceptibles d'ouvrir une nouvelle fenêtre d'observation sur le cosmos. La collaboration ANTARES a construit en Méditerranée un télescope sous-marin de neutrino de haute énergie d'une surface de détection proche de 0.1 km². C'est le télescope le plus sensible pour la partie du ciel observée. Les interféromètres VIRGO et LIGO sont des détecteurs terrestres pour l'observation directe d'ondes gravitationnelles, instalés en Europe et aux états-Unis d'Amérique respectivement. Les instruments ANTARES, VIRGO et LIGO offrent une sensibilité inégalée dans la zone de recherche commune. Le premier chapitre de cette thèse introduit les motivations théoriques pour une recherche jointe d'ondes gravitationnelles et de neutrinos de haute énergies en développant les différents scénarios d'émission. Le deuxième et troisième chapitres sont consacrés à l'étude des techniques de détection avec les interféromètres VIRGO-LIGO et le télescope à neutrinos ANTARES. Les quatriéme et cinquième chapitres de ce travail présentent les résultats d'analyses de données combinées d'ANTARES, VIRGO et LIGO prises séparement pendant les années 2007 et 2009-2010.

This thesis presents work around 3 themes: dark energy, gravitational waves and Bayesian inference. Both dark energy and gravitational wave physics are not yet well constrained. They present interesting challenges for Bayesian inference, which attempts to quantify our knowledge of the universe given our astrophysical data. A dark energy equation of state reconstruction analysis finds that the data favours the vacuum dark energy equation of state $w {=} -1$ model. Deviations from vacuum dark energy are shown to favour the super-negative ‘phantom’ dark energy regime of $w {< } -1$, but at low statistical significance. The constraining power of various datasets is quantified, finding that data constraints peak around redshift $z = 0.2$ due to baryonic acoustic oscillation and supernovae data constraints, whilst cosmic microwave background radiation and Lyman-$\alpha$ forest constraints are less significant. Specific models with a conformal time symmetry in the Friedmann equation and with an additional dark energy component are tested and shown to be competitive to the vacuum dark energy model by Bayesian model selection analysis: that they are not ruled out is believed to be largely due to poor data quality for deciding between existing models. Recent detections of gravitational waves by the LIGO collaboration enable the first gravitational wave tests of general relativity. An existing test in the literature is used and sped up significantly by a novel method developed in this thesis. The test computes posterior odds ratios, and the new method is shown to compute these accurately and efficiently. Compared to computing evidences, the method presented provides an approximate 100 times reduction in the number of likelihood calculations required to compute evidences at a given accuracy. Further testing may identify a significant advance in Bayesian model selection using nested sampling, as the method is completely general and straightforward to implement. We note that efficiency gains are not guaranteed and may be problem specific: further research is needed.

The aim of this doctoral thesis was to study the incidence, risk factors and outcomes of type 1 diabetes for children in South Australia, born from 1999-2013. The incidence of type 1 diabetes has doubled in the last four decades in many countries including Australia, and has substantial individual and economic consequences. Evidence from studies on type 1 diabetes aetiology and its implications is mixed. In this thesis, the linkage of multiple population-wide administrative data over 15 years, and use of rigorous epidemiological approaches has resulted in a better understanding of the risk factors and implications of type 1 diabetes. There are four studies in this doctoral thesis. In the first descriptive study, the incidence of type 1 diabetes was estimated by individual and area-level socioeconomic characteristics among children (aged ≤11 years) in South Australia, born from 2002-2013. Findings of the study showed that type 1 diabetes incidence rates differed depending on the measures of socioeconomic characteristics. Individual-level indicators showed higher type 1 diabetes incidence among more advantaged children, however, there was no clear area-level socioeconomic patterning of type 1 diabetes. Area-level measures of socioeconomic position are likely to have a greater risk of misclassification from true socioeconomic position, which suggests that the use of area-level measures may be misleading. Socioeconomic position is a major determinant of health and can modify the risk factors of type 1 diabetes. For example, as per hygiene hypothesis, the socioeconomically dis-advantaged children are less likely to have type 1 diabetes, which is supported by the findings of individual-level socioeconomic patterning of type1 diabetes in the first study. In addition, socioeconomically disadvantaged women are less likely to have a caesarean birth and more likely to smoke in pregnancy. I chose to study these two risk factors of type 1 diabetes because the evidence was inconsistent, and some studies had methodical limitations. Evidence about the effect of caesarean section on childhood type 1 diabetes is mixed; ranging from very small or no risk to 20-30% increased risk. A prevailing theory is that exposure to the gut and vaginal microbiota during a vaginal birth protects against type 1 diabetes. Therefore, in the second study, the impact of caesarean birth on childhood type 1 diabetes (aged ≤15 years) was estimated. This involved linking multiple administrative datasets of children in South Australia, born from 1999-2013. The question was extended to whether type 1 diabetes risk differed for children born by prelabour or intrapartum caesarean to further test the idea of microbiota exposure on type 1 diabetes. That is because children born by prelabour caesarean do not get exposure to maternal vaginal microbiota, and intrapartum caesarean births may have some exposure. Findings of the study obtained from Cox proportional hazard regression analysis showed a negligible 5% higher incidence (HR = 1.05, 95% CI 0.86-1.28) for caesarean births compared with normal vaginal delivery, with wide confidence intervals including the null. Contrary to the hypothesis of a higher type 1 diabetes risk for prelabor caesarean (because of non-exposure to maternal vaginal microbiota) type 1 diabetes risk for intrapartum caesarean was slightly higher (HR = 1.08, 95% CI 0.82-1.41) than prelabor caesarean (HR = 1.02, 95% CI 0.79-1.32). This negligible risk of type 1 diabetes for children who had caesarean birth, either prelabor or intrapartum, and the potential for unmeasured confounding suggested that birth method induced variation in neonatal microbiota might not be involved in modifying type 1 diabetes risk. Like caesarean section, maternal smoking in pregnancy is also a debated risk factor for childhood type 1 diabetes. Evidence about maternal smoking on childhood type 1 diabetes is inconsistent; studies have been small, and many did not adjust for important confounders or address missing data. In the third study of this doctoral thesis, the effect of maternal smoking in pregnancy on childhood type 1 diabetes was estimated using Cox proportional hazard regression analysis, once again by linking multiple administrative datasets of children in South Australia, born from 1999-2013. The analytical approach for this study ranged; from Cox proportional hazard analysis with adjustment for wide range of confounders using the SA ECDP linked data, involving multiple imputation for missing data; to conducting meta-analysis in order to get more precise estimate. But smoking is notoriously residually confounded, therefore, I made special efforts to investigate the possibility of residual confounding by using a negative control and E-value. The findings demonstrated that maternal smoking in pregnancy was associated with a 16% (HR 0.84, 95% CI 0.67, 1.08) lower childhood type 1 diabetes incidence, compared with unexposed children, which was also supported by the meta-analytic estimates of population-based cohort studies (HR 0.72, 95% CI 0.62, 0.82) and case-control studies (OR 0.71, 95% CI 0.55, 0.86). The negative control outcome and E-value analyses indicated the potential for residual confounding in the effect of maternal smoking on childhood type 1 diabetes. Triangulation of evidence from this study along with the results of similar population-based studies, suggested a small reduced risk of childhood type 1 diabetes for children exposed to maternal smoking in pregnancy. However, the mechanisms linking maternal smoking in pregnancy with childhood type 1 diabetes require further investigation. In the fourth study of this thesis, the impact of childhood type 1 diabetes on children’s educational outcomes in year/grade 5 at age ~10 were estimated, linking population-wide data of children in South Australia, born from 1999-2005. In this study, a doubly-robust analytical method called augmented inverse probability weighting (AIPW) was used to compute the average treatment effect of type 1 diabetes on children’s educational outcomes. AIPW gives an unbiased estimate if either the outcome model or the treatment model is correctly specified. The findings of this study demonstrated that children with type 1 diabetes are not disadvantaged in terms of educational outcomes in year 5, potentially reflecting improvement in type 1 diabetes management in Australia. In summary, the work in this doctoral thesis has demonstrated that type 1 diabetes incidence differed depending on the measure of socioeconomic position. The hygiene hypothesis was only supported by the individual-level socioeconomic pattering of type 1 diabetes incidence in South Australia. The involvement of birth method induced variation in neonatal microbiota in type 1 diabetes was not supported by the caesarean and childhood type 1 diabetes study. Despite the evidence of residual confounding in the estimate of maternal smoking in pregnancy on childhood type 1 diabetes, triangulation of the evidence suggested small reduced risk for children exposed to maternal smoking in pregnancy, but further research will be needed to understand the mechanism. The findings of similar educational outcomes for children with and without type 1 diabetes, highlighted the importance of improvements in diabetes management.
Thesis (Ph.D.) -- University of Adelaide, School of Public Health, 2020

Advanced LIGO's first observing run marked the birth of gravitational-wave astronomy through the first detection of gravitational waves from coalescing black holes-GW150914. Advanced LIGO's second and Advanced Virgo's first observing run marked the birth of multimessenger astronomy with first joint observations of gravitational and electromagnetic radiation associated with coalescing neutron stars-GW170817. The electromagnetic observations included detection of a burst of gamma rays produced by the merger, and a kilonova powered by the radioactive decay of r-process nuclei synthesized in the neutron star coalescence ejecta. Gravitational waves from compact binary coalescences carry fingerprints of the sources that generated them. Studying them allows us to test Einstein’s general relativity in the strongest regimes, where it has never been tested before, and study matter at densities beyond reach of the most powerful laboratories on our planet. Moreover, we can gain insight about the evolution of stars, galaxies and even the Universe as a whole by studying the merger rate of compact objects. Joint electromagnetic and gravitational-wave observations help develop our understanding of the physical processes that occur in such systems, and provide a new method of probing cosmological parameters.

GW170817 was detected by the GstLAL pipeline in low-latency making the extensive electromagnetic followup possible. The GstLAL pipeline is a matched filtering pipeline that uses compact binary coalescence waveform models to filter the data from gravitational-wave detectors in the time-domain. It can detect gravitational waves from coalescing compact binaries in near real time and provide point estimates for binary parameters. This thesis describes the methods, developments, and the results from the GstLAL pipeline over the course of the first two observing runs of Advanced LIGO, focusing on the contributions made by the author. We also present a study about the prospects of observing a cosmological stochastic background which is expected to be buried under the astrophysical background from the population of coalesceing compact binaries with third-generation gravitational-wave detectors.

According to General Relativity a perturbed black hole will return to a stable configuration by the emission of gravitational radiation in a superposition of quasi-normal modes. Such a perturbation will occur due to the coalescence of a black hole binary, following their inspiral and subsequent merger. At late times the waveform, which we refer to as a ringdown, is expected to be dominated by a single mode. As the waveform is well-known the method of matched filtering can be implemented to search for this signal using LIGO data. LIGO is sensitive to the dominant mode of perturbed black holes with masses between 10 and 500 Msun, the regime of intermediate-mass black holes, to a distance of up to 300 Mpc. We present a search for gravitational waves from black hole ringdowns using data from the fourth LIGO science run. We implement a blind analysis of the data. We use Monte Carlo simulations of the expected waveform, and an estimation of the background from timeslides to tune the search. We present an analysis of the waveform parameter estimation and estimate the efficiency of the search. As there were no gravitational wave candidates found, we place an upper limit on the rate of black hole ringdowns in the local universe.

This is an exciting time for Gravitational Wave (GW) theory and observations. From a theoretical standpoint, the grand-challenge problem of the full evolution of a Binary Black Hole (BBH) system has been solved numerically, and a variety of source simulations are made available steadfastly. On the observational side, the first generation of state-of-the-art GW detectors, LIGO and Virgo, have achieved their design goal, collected data and provided astrophysically meaningful limits. The second generation of detectors are expected to start running by 2015. Inspired by this zeitgeist, this thesis focuses on the detection of potential GW signatures from the coalescence of BBH in ground-based laser interferometers. The LIGO Scientific Collaboration has implemented different algorithms to search for transient GW signatures, targeting different portions of the BBH coalescence waveform. This thesis has used the existing algorithms to study the detection potential of GW from colliding BBH in LIGO in a wide range of source parameters, such as mass and spin of the black holes, using a sample of data from the last two months of the S5 LIGO science run (14 Aug 2007 to 30 Sept 2007). This thesis also uses numerical relativity waveforms made available via the Numerical INJection Analysis project (NINJA). Methods such as the Chirplet based analysis and the use of multivariate classifiers to optimize burst search algorithms have been introduced in this thesis. These performance studies over a wide parameter space were designed to optimize the discovery potential of ground-based GW detectors and defining strategies for the search of BBH signatures in advanced LIGO data, as a step towards the realization of GW astronomy.

Static terrestrial laser scanners have been increasingly used in three-dimensional data acquisition since it can rapidly provide accurate measurements with high resolution. Several scans from multiple viewpoints are necessary to achieve complete coverage of the surveyed objects due to occlusion and large object size. Therefore, in order to reconstruct three-dimensional models of the objects, the task of registration is required to transform several individual scans into a common reference frame. This thesis introduces three alternative approaches for the coarse registration of two adjacent scans, namely, feature-based approach, pseudo-conjugate point-based method, and closed-form solution. In the feature-based approach, linear and planar features in the overlapping area of adjacent scans are selected as registration primitives. The pseudo-conjugate point-based method utilizes non-corresponding points along common linear and planar features to estimate transformation parameters. The pseudo-conjugate point-based method is simpler than the feature-based approach since the partial derivatives are easier to compute. In the closed-form solution, a rotation matrix is first estimated by using a unit quaternion, which is a concise description of the rotation. Afterward, the translation parameters are estimated with non-corresponding points along the linear or planar features by using the pseudo-conjugate point-based method. Alternative approaches for fitting a line or plane to data with errors in three-dimensional space are investigated.

Experiments are conducted using simulated and real datasets to verify the effectiveness of the introduced registration procedures and feature fitting approaches. The proposed two approaches of line fitting are tested with simulated datasets. The results suggest that these two approaches can produce identical line parameters and variance-covariance matrix. The three registration approaches are tested with both simulated and real datasets. In the simulated datasets, all three registration approaches produced equivalent transformation parameters using linear or planar features. The comparison between the simulated linear and planar features shows that both features can produce equivalent registration results. In the real datasets, the three registration approaches using the linear or planar features also produced equivalent results. In addition, the results using real data indicates that the registration approaches using planar features produced better results than the approaches using linear features. The experiments show that the pseudo-conjugate point-based approach is easier to implement than the feature-based approach. The pseudo-conjugate point-based method and feature-based approach are nonlinear, so an initial guess of transformation parameters is required in these two approaches. Compared to the nonlinear approaches, the closed-form solution is linear and hence it can achieve the registration of two adjacent scans without the requirement of any initial guess for transformation parameters. Therefore, the pseudo-conjugate point-based method and closed-form solution are the preferred approaches for coarse registration using linear or planar features. In real practice, the planar features would have a better preference when compared to linear features since the linear features are derived indirectly by the intersection of neighboring planar features. To get enough lines with different orientations, planes that are far apart from each other have to be extrapolated to derive lines.

The LIGO and Virgo gravitational-wave observatories are complex and extremely sensitive strain detectors that can be used to search for a wide variety of gravitational waves from astrophysical and cosmological sources. In this thesis, I motivate the search for the gravitational wave signals from coalescing black hole binary systems with total mass between 25 and 100 solar masses. The mechanisms for formation of such systems are not well-understood, and we do not have many observational constraints on the parameters that guide the formation scenarios. Detection of gravitational waves from such systems — or, in the absence of detection, the tightening of upper limits on the rate of such coalescences — will provide valuable information that can inform the astrophysics of the formation of these systems. I review the search for these systems and place upper limits on the rate of black hole binary coalescences with total mass between 25 and 100 solar masses. I then show how the sensitivity of this search can be improved by up to 40% by the the application of the multivariate statistical classifier known as a random forest of bagged decision trees to more effectively discriminate between signal and non-Gaussian instrumental noise. I also discuss the use of this classifier in the search for the ringdown signal from the merger of two black holes with total mass between 50 and 450 solar masses and present upper limits. I also apply multivariate statistical classifiers to the problem of quantifying the non-Gaussianity of LIGO data. Despite these improvements, no gravitational-wave signals have been detected in LIGO data so far. However, the use of multivariate statistical classification can significantly improve the sensitivity of the Advanced LIGO detectors to such signals.