474 research outputs found
Contribution to Graph-based Manifold Learning with Application to Image Categorization.
122 pLos algoritmos de aprendizaje de variedades basados en grafos (Graph,based manifold) son técnicas que han demostrado ser potentes herramientas para la extracción de características y la reducción de la dimensionalidad en los campos de reconomiento de patrones, visión por computador y aprendizaje automático. Estos algoritmos utilizan información basada en las similitudes de pares de muestras y del grafo ponderado resultante para revelar la estructura geométrica intrínseca de la variedad
Contribution to Graph-based Manifold Learning with Application to Image Categorization.
122 pLos algoritmos de aprendizaje de variedades basados en grafos (Graph,based manifold) son técnicas que han demostrado ser potentes herramientas para la extracción de características y la reducción de la dimensionalidad en los campos de reconomiento de patrones, visión por computador y aprendizaje automático. Estos algoritmos utilizan información basada en las similitudes de pares de muestras y del grafo ponderado resultante para revelar la estructura geométrica intrínseca de la variedad
A Review on Non Linear Dimensionality Reduction Techniques for Face Recognition
Principal component Analysis (PCA) has gained much attention among researchers to address the pboblem of high dimensional data sets.during last decade a non-linear variantof PCA has been used to reduce the dimensions on a non linear hyperplane.This paper reviews the various Non linear techniques ,applied on real and artificial data .It is observed that Non-Linear PCA outperform in the counterpart in most cases .However exceptions are noted
Behaviour Profiling using Wearable Sensors for Pervasive Healthcare
In recent years, sensor technology has advanced in terms of hardware sophistication and miniaturisation. This has led to the incorporation of unobtrusive, low-power sensors into networks centred on human participants, called Body Sensor Networks. Amongst the most important applications of these networks is their use in healthcare and healthy living. The technology has the possibility of decreasing burden on the healthcare systems by providing care at home, enabling early detection of symptoms, monitoring recovery remotely, and avoiding serious chronic illnesses by promoting healthy living through objective feedback. In this thesis, machine learning and data mining techniques are developed to estimate medically relevant parameters from a participant‘s activity and behaviour parameters, derived from simple, body-worn sensors.
The first abstraction from raw sensor data is the recognition and analysis of activity. Machine learning analysis is applied to a study of activity profiling to detect impaired limb and torso mobility. One of the advances in this thesis to activity recognition research is in the application of machine learning to the analysis of 'transitional activities': transient activity that occurs as people change their activity. A framework is proposed for the detection and analysis of transitional activities. To demonstrate the utility of transition analysis, we apply the algorithms to a study of participants undergoing and recovering from surgery. We demonstrate that it is possible to see meaningful changes in the transitional activity as the participants recover.
Assuming long-term monitoring, we expect a large historical database of activity to quickly accumulate. We develop algorithms to mine temporal associations to activity patterns. This gives an outline of the user‘s routine. Methods for visual and quantitative analysis of routine using this summary data structure are proposed and validated. The activity and routine mining methodologies developed for specialised sensors are adapted to a smartphone application, enabling large-scale use. Validation of the algorithms is performed using datasets collected in laboratory settings, and free living scenarios. Finally, future research directions and potential improvements to the techniques developed in this thesis are outlined
Nonlinear Supervised Dimensionality Reduction via Smooth Regular Embeddings
The recovery of the intrinsic geometric structures of data collections is an
important problem in data analysis. Supervised extensions of several manifold
learning approaches have been proposed in the recent years. Meanwhile, existing
methods primarily focus on the embedding of the training data, and the
generalization of the embedding to initially unseen test data is rather
ignored. In this work, we build on recent theoretical results on the
generalization performance of supervised manifold learning algorithms.
Motivated by these performance bounds, we propose a supervised manifold
learning method that computes a nonlinear embedding while constructing a smooth
and regular interpolation function that extends the embedding to the whole data
space in order to achieve satisfactory generalization. The embedding and the
interpolator are jointly learnt such that the Lipschitz regularity of the
interpolator is imposed while ensuring the separation between different
classes. Experimental results on several image data sets show that the proposed
method outperforms traditional classifiers and the supervised dimensionality
reduction algorithms in comparison in terms of classification accuracy in most
settings
Multi-Source Data Fusion for Cyberattack Detection in Power Systems
Cyberattacks can cause a severe impact on power systems unless detected
early. However, accurate and timely detection in critical infrastructure
systems presents challenges, e.g., due to zero-day vulnerability exploitations
and the cyber-physical nature of the system coupled with the need for high
reliability and resilience of the physical system. Conventional rule-based and
anomaly-based intrusion detection system (IDS) tools are insufficient for
detecting zero-day cyber intrusions in the industrial control system (ICS)
networks. Hence, in this work, we show that fusing information from multiple
data sources can help identify cyber-induced incidents and reduce false
positives. Specifically, we present how to recognize and address the barriers
that can prevent the accurate use of multiple data sources for fusion-based
detection. We perform multi-source data fusion for training IDS in a
cyber-physical power system testbed where we collect cyber and physical side
data from multiple sensors emulating real-world data sources that would be
found in a utility and synthesizes these into features for algorithms to detect
intrusions. Results are presented using the proposed data fusion application to
infer False Data and Command injection-based Man-in- The-Middle (MiTM) attacks.
Post collection, the data fusion application uses time-synchronized merge and
extracts features followed by pre-processing such as imputation and encoding
before training supervised, semi-supervised, and unsupervised learning models
to evaluate the performance of the IDS. A major finding is the improvement of
detection accuracy by fusion of features from cyber, security, and physical
domains. Additionally, we observed the co-training technique performs at par
with supervised learning methods when fed with our features
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