Machine learning in astronomy

The search to find answers to the deepest questions we have about the Universe has fueled the collection of data for ever larger volumes of our cosmos. The field of supernova cosmology, for example, is seeing continuous development with upcoming surveys set to produce a vast amount of data that will require new statistical inference and machine learning techniques for processing and analysis. Distinguishing between real objects and artefacts is one of the first steps in any transient science pipeline and, currently, is still carried out by humans - often leading to hand scanners having to sort hundreds or thousands of images per night. This is a time-consuming activity introducing human biases that are extremely hard to characterise. To succeed in the objectives of future transient surveys, the successful substitution of human hand scanners with machine learning techniques for the purpose of this artefact-transient classification therefore represents a vital frontier. In this thesis we test various machine learning algorithms and show that many of them can match the human hand scanner performance in classifying transient difference g, r and i-band imaging data from the SDSS-II SN Survey into real objects and artefacts. Using principal component analysis and linear discriminant analysis, we construct a grand total of 56 feature sets with which to train, optimise and test a Minimum Error Classifier (MEC), a naive Bayes classifier, a k-Nearest Neighbours (kNN) algorithm, a Support Vector Machine (SVM) and the SkyNet artificial neural network

Segmentation and supervised classification of image objects in Epo doping-control

Abstract A software system Gel Analysis System for Epo (GASepo) has been developed within an international WADA project. As recent WADA criteria of rEpo positivity are based on identification of each relevant object (band) in Epo images, development of suitable methods of image segmentation and object classification were needed for the GASepo system. In the paper we address two particular problems: segmentation of disrupted bands and classification of the segmented objects into three or two classes. A novel band projection operator is based on convenient object merging measures and their discrimination analysis using specifically generated training set of segmented objects. A weighted ranks classification method is proposed, which is new in the field of image classification. It is based on ranks of the values of a specific criterial function. The weighted ranks classifiers proposed in our paper have been evaluated on real samples of segmented objects of Epo images and compared t

Análise visual aplicada à análise de imagens

Orientadores: Alexandre Xavier Falcão, Alexandru Cristian Telea, Pedro Jussieu de Rezende, Johannes Bernardus Theodorus Maria RoerdinkTese (doutorado) - Universidade Estadual de Campinas, Instituto de Computação e Universidade de GroningenResumo: Análise de imagens é o campo de pesquisa preocupado com a extração de informações a partir de imagens. Esse campo é bastante importante para aplicações científicas e comerciais. O objetivo principal do trabalho apresentado nesta tese é permitir interatividade com o usuário durante várias tarefas relacionadas à análise de imagens: segmentação, seleção de atributos, e classificação. Neste contexto, permitir interatividade com o usuário significa prover mecanismos que tornem possível que humanos auxiliem computadores em tarefas que são de difícil automação. Com respeito à segmentação de imagens, propomos uma nova técnica interativa que combina superpixels com a transformada imagem-floresta. A vantagem principal dessa técnica é permitir rápida segmentação interativa de imagens grandes, além de permitir extração de características potencialmente mais ricas. Os experimentos sugerem que nossa técnica é tão eficaz quanto a alternativa baseada em pixels. No contexto de seleção de atributos e classificação, propomos um novo sistema de visualização interativa que combina exploração do espaço de atributos (baseada em redução de dimensionalidade) com avaliação automática de atributos. Esse sistema tem como objetivo revelar informações que levem ao desenvolvimento de conjuntos de atributos eficazes para classificação de imagens. O mesmo sistema também pode ser aplicado para seleção de atributos para segmentação de imagens e para classificação de padrões, apesar dessas tarefas não serem nosso foco. Apresentamos casos de uso que mostram como esse sistema pode prover certos tipos de informação qualitativa sobre sistemas de classificação de imagens que seriam difíceis de obter por outros métodos. Também mostramos como o sistema interativo proposto pode ser adaptado para a exploração de resultados computacionais intermediários de redes neurais artificiais. Essas redes atualmente alcançam resultados no estado da arte em muitas aplicações de classificação de imagens. Através de casos de uso envolvendo conjuntos de dados de referência, mostramos que nosso sistema pode prover informações sobre como uma rede opera que levam a melhorias em sistemas de classificação. Já que os parâmetros de uma rede neural artificial são tipicamente adaptados iterativamente, a visualização de seus resultados intermediários pode ser vista como uma tarefa dependente de tempo. Com base nessa perspectiva, propomos uma nova técnica de redução de dimensionalidade dependente de tempo que permite a redução de mudanças desnecessárias nos resultados causadas por pequenas mudanças nos dados. Experimentos preliminares mostram que essa técnica é eficaz em manter a coerência temporal desejadaAbstract: We define image analysis as the field of study concerned with extracting information from images. This field is immensely important for commercial and interdisciplinary applications. The overarching goal behind the work presented in this thesis is enabling user interaction during several tasks related to image analysis: image segmentation, feature selection, and image classification. In this context, enabling user interaction refers to providing mechanisms that allow humans to assist machines in tasks that are difficult to automate. Such tasks are very common in image analysis. Concerning image segmentation, we propose a new interactive technique that combines superpixels with the image foresting transform. The main advantage of our proposed technique is enabling faster interactive segmentation of large images, although it also enables potentially richer feature extraction. Our experiments show that our technique is at least as effective as its pixel-based counterpart. In the context of feature selection and image classification, we propose a new interactive visualization system that combines feature space exploration (based on dimensionality reduction) with automatic feature scoring. This visualization system aims to provide insights that lead to the development of effective feature sets for image classification. The same system can also be applied to select features for image segmentation and (general) pattern classification, although these tasks are not our focus. We present use cases that show how this system may provide a kind of qualitative feedback about image classification systems that would be very difficult to obtain by other (non-visual) means. We also show how our proposed interactive visualization system can be adapted to explore intermediary computational results of artificial neural networks. Such networks currently achieve state-of-the-art results in many image classification applications. Through use cases involving traditional benchmark datasets, we show that our system may enable insights about how a network operates that lead to improvements along the classification pipeline. Because the parameters of an artificial neural network are typically adapted iteratively, visualizing its intermediary computational results can be seen as a time-dependent task. Motivated by this, we propose a new time-dependent dimensionality reduction technique that enables the reduction of apparently unnecessary changes in results due to small changes in the data (temporal coherence). Preliminary experiments show that this technique is effective in enforcing temporal coherenceDoutoradoCiência da ComputaçãoDoutor em Ciência da Computação2012/24121-9;FAPESPCAPE

Reliability problems in eartquake engineering

This monograph deals with the problem of reliability analysis in the field of Earthquake Engineering. Chapter 1 is devoted to a summary of the most widely used reliability methods, with emphasis on Monte Carlo and solver surrogate techniques used in the subsequent chapters. Chapter 2 presents a discussion of the Monte Carlo from the viewpoint of Information Theory. Then, a discussion is made in Chapter 3 on the selection of random variables in Earthquake Engineering. Next, some practical methods for computing failure probabilities under seismic loads are reported in Chapter 4. Finally, a method for reliability-based design optimization under seismic loads is presented in Chapter 5

COMPUTATIONAL MODELLING OF HUMAN AESTHETIC PREFERENCES IN THE VISUAL DOMAIN: A BRAIN-INSPIRED APPROACH

Following the rise of neuroaesthetics as a research domain, computational aesthetics has also known a regain in popularity over the past decade with many works using novel computer vision and machine learning techniques to evaluate the aesthetic value of visual information. This thesis presents a new approach where low-level features inspired from the human visual system are extracted from images to train a machine learning-based system to classify visual information depending on its aesthetics, regardless of the type of visual media. Extensive tests are developed to highlight strengths and weaknesses of such low-level features while establishing good practices in the domain of study of computational aesthetics. The aesthetic classification system is not only tested on the most widely used dataset of photographs, called AVA, on which it is trained initially, but also on other photographic datasets to evaluate the robustness of the learnt aesthetic preferences over other rating communities. The system is then assessed in terms of aesthetic classification on other types of visual media to investigate whether the learnt aesthetic preferences represent photography rules or more general aesthetic rules. The skill transfer from aesthetic classification of photos to videos demonstrates a satisfying correct classification rate of videos without any prior training on the test set created by Tzelepis et al. Moreover, the initial photograph classifier can also be used on feature films to investigate the classifier’s learnt visual preferences, due to films providing a large number of frames easily labellable. The study on aesthetic classification of videos concludes with a case study on the work by an online content creator. The classifier recognised a significantly greater percentage of aesthetically high frames in videos filmed in studios than on-the-go. The results obtained across datasets containing videos of diverse natures manifest the extent of the system’s aesthetic knowledge. To conclude, the evolution of low-level visual features is studied in popular culture such as in paintings and brand logos. The work attempts to link aesthetic preferences during contemplation tasks such as aesthetic rating of photographs with preferred low-level visual features in art creation. It questions whether favoured visual features usage varies over the life of a painter, implicitly showing a relationship with artistic expertise. Findings display significant changes in use of universally preferred features over influential vi abstract painters’ careers such an increase in cardinal lines and the colour blue; changes that were not observed in landscape painters. Regarding brand logos, only a few features evolved in a significant manner, most of them being colour-related features. Despite the incredible amount of data available online, phenomena developing over an entire life are still complicated to study. These computational experiments show that simple approaches focusing on the fundamentals instead of high-level measures allow to analyse artists’ visual preferences, as well as extract a community’s visual preferences from photos or videos while limiting impact from cultural and personal experiences

Operator State Estimation for Adaptive Aiding in Uninhabited Combat Air Vehicles

This research demonstrated the first closed-loop implementation of adaptive automation using operator functional state in an operationally relevant environment. In the Uninhabited Combat Air Vehicle (UCAV) environment, operators can become cognitively overloaded and their performance may decrease during mission critical events. This research demonstrates an unprecedented closed-loop system, one that adaptively aids UCAV operators based on their cognitive functional state A series of experiments were conducted to 1) determine the best classifiers for estimating operator functional state, 2) determine if physiological measures can be used to develop multiple cognitive models based on information processing demands and task type, 3) determine the salient psychophysiological measures in operator functional state, and 4) demonstrate the benefits of intelligent adaptive aiding using operator functional state. Aiding the operator actually improved performance and increased mission effectiveness by 67%

Non-Contact Sleep Monitoring

"The road ahead for preventive medicine seems clear. It is the delivery of high quality, personalised (as opposed to depersonalised) comprehensive medical care to all." Burney, Steiger, and Georges (1964) This world's population is ageing, and this is set to intensify over the next forty years. This demographic shift will result in signicant economic and societal burdens (partic- ularly on healthcare systems). The instantiation of a proactive, preventative approach to delivering healthcare is long recognised, yet is still proving challenging. Recent work has focussed on enabling older adults to age in place in their own homes. This may be realised through the recent technological advancements of aordable healthcare sen- sors and systems which continuously support independent living, particularly through longitudinally monitoring deviations in behavioural and health metrics. Overall health status is contingent on multiple factors including, but not limited to, physical health, mental health, and social and emotional wellbeing; sleep is implicitly linked to each of these factors. This thesis focusses on the investigation and development of an unobtrusive sleep mon- itoring system, particularly suited towards long-term placement in the homes of older adults. The Under Mattress Bed Sensor (UMBS) is an unobstrusive, pressure sensing grid designed to infer bed times and bed exits, and also for the detection of development of bedsores. This work extends the capacity of this sensor. Specically, the novel contri- butions contained within this thesis focus on an in-depth review of the state-of-the-art advances in sleep monitoring, and the development and validation of algorithms which extract and quantify UMBS-derived sleep metrics. Preliminary experimental and community deployments investigated the suitability of the sensor for long-term monitoring. Rigorous experimental development rened algorithms which extract respiration rate as well as motion metrics which outperform traditional forms of ambulatory sleep monitoring. Spatial, temporal, statistical and spatiotemporal features were derived from UMBS data as a means of describing movement during sleep. These features were compared across experimental, domestic and clinical data sets, and across multiple sleeping episodes. Lastly, the optimal classier (built using a combina- tion of the UMBS-derived features) was shown to infer sleep/wake state accurately and reliably across both younger and older cohorts. Through long-term deployment, it is envisaged that the UMBS-derived features (in- cluding spatial, temporal, statistical and spatiotemporal features, respiration rate, and sleep/wake state) may be used to provide unobtrusive, continuous insights into over- all health status, the progression of the symptoms of chronic conditions, and allow the objective measurement of daily (sleep/wake) patterns and routines