1,717 research outputs found
Neural activity classification with machine learning models trained on interspike interval series data
The flow of information through the brain is reflected by the activity
patterns of neural cells. Indeed, these firing patterns are widely used as
input data to predictive models that relate stimuli and animal behavior to the
activity of a population of neurons. However, relatively little attention was
paid to single neuron spike trains as predictors of cell or network properties
in the brain. In this work, we introduce an approach to neuronal spike train
data mining which enables effective classification and clustering of neuron
types and network activity states based on single-cell spiking patterns. This
approach is centered around applying state-of-the-art time series
classification/clustering methods to sequences of interspike intervals recorded
from single neurons. We demonstrate good performance of these methods in tasks
involving classification of neuron type (e.g. excitatory vs. inhibitory cells)
and/or neural circuit activity state (e.g. awake vs. REM sleep vs. nonREM sleep
states) on an open-access cortical spiking activity dataset
Process Monitoring and Data Mining with Chemical Process Historical Databases
Modern chemical plants have distributed control systems (DCS) that handle normal operations and quality control. However, the DCS cannot compensate for fault events such as fouling or equipment failures. When faults occur, human operators must rapidly assess the situation, determine causes, and take corrective action, a challenging task further complicated by the sheer number of sensors. This information overload as well as measurement noise can hide information critical to diagnosing and fixing faults. Process monitoring algorithms can highlight key trends in data and detect faults faster, reducing or even preventing the damage that faults can cause. This research improves tools for process monitoring on different chemical processes. Previously successful monitoring methods based on statistics can fail on non-linear processes and processes with multiple operating states. To address these challenges, we develop a process monitoring technique based on multiple self-organizing maps (MSOM) and apply it in industrial case studies including a simulated plant and a batch reactor. We also use standard SOM to detect a novel event in a separation tower and produce contribution plots which help isolate the causes of the event. Another key challenge to any engineer designing a process monitoring system is that implementing most algorithms requires data organized into “normal” and “faulty”; however, data from faulty operations can be difficult to locate in databases storing months or years of operations. To assist in identifying faulty data, we apply data mining algorithms from computer science and compare how they cluster chemical process data from normal and faulty conditions. We identify several techniques which successfully duplicated normal and faulty labels from expert knowledge and introduce a process data mining software tool to make analysis simpler for practitioners. The research in this dissertation enhances chemical process monitoring tasks. MSOM-based process monitoring improves upon standard process monitoring algorithms in fault identification and diagnosis tasks. The data mining research reduces a crucial barrier to the implementation of monitoring algorithms. The enhanced monitoring introduced can help engineers develop effective and scalable process monitoring systems to improve plant safety and reduce losses from fault events
There and Back Again: Self-supervised Multispectral Correspondence Estimation
Across a wide range of applications, from autonomous vehicles to medical
imaging, multi-spectral images provide an opportunity to extract additional
information not present in color images. One of the most important steps in
making this information readily available is the accurate estimation of dense
correspondences between different spectra.
Due to the nature of cross-spectral images, most correspondence solving
techniques for the visual domain are simply not applicable. Furthermore, most
cross-spectral techniques utilize spectra-specific characteristics to perform
the alignment. In this work, we aim to address the dense correspondence
estimation problem in a way that generalizes to more than one spectrum. We do
this by introducing a novel cycle-consistency metric that allows us to
self-supervise. This, combined with our spectra-agnostic loss functions, allows
us to train the same network across multiple spectra.
We demonstrate our approach on the challenging task of dense RGB-FIR
correspondence estimation. We also show the performance of our unmodified
network on the cases of RGB-NIR and RGB-RGB, where we achieve higher accuracy
than similar self-supervised approaches. Our work shows that cross-spectral
correspondence estimation can be solved in a common framework that learns to
generalize alignment across spectra
Recurrences reveal shared causal drivers of complex time series
Many experimental time series measurements share unobserved causal drivers.
Examples include genes targeted by transcription factors, ocean flows
influenced by large-scale atmospheric currents, and motor circuits steered by
descending neurons. Reliably inferring this unseen driving force is necessary
to understand the intermittent nature of top-down control schemes in diverse
biological and engineered systems. Here, we introduce a new unsupervised
learning algorithm that uses recurrences in time series measurements to
gradually reconstruct an unobserved driving signal. Drawing on the mathematical
theory of skew-product dynamical systems, we identify recurrence events shared
across response time series, which implicitly define a recurrence graph with
glass-like structure. As the amount or quality of observed data improves, this
recurrence graph undergoes a percolation transition manifesting as weak
ergodicity breaking for random walks on the induced landscape -- revealing the
shared driver's dynamics, even in the presence of strongly corrupted or noisy
measurements. Across several thousand random dynamical systems, we empirically
quantify the dependence of reconstruction accuracy on the rate of information
transfer from a chaotic driver to the response systems, and we find that
effective reconstruction proceeds through gradual approximation of the driver's
dominant orbit topology. Through extensive benchmarks against classical and
neural-network-based signal processing techniques, we demonstrate our method's
strong ability to extract causal driving signals from diverse real-world
datasets spanning ecology, genomics, fluid dynamics, and physiology.Comment: 8 pages, 5 figure
SALSA: A Novel Dataset for Multimodal Group Behavior Analysis
Studying free-standing conversational groups (FCGs) in unstructured social
settings (e.g., cocktail party ) is gratifying due to the wealth of information
available at the group (mining social networks) and individual (recognizing
native behavioral and personality traits) levels. However, analyzing social
scenes involving FCGs is also highly challenging due to the difficulty in
extracting behavioral cues such as target locations, their speaking activity
and head/body pose due to crowdedness and presence of extreme occlusions. To
this end, we propose SALSA, a novel dataset facilitating multimodal and
Synergetic sociAL Scene Analysis, and make two main contributions to research
on automated social interaction analysis: (1) SALSA records social interactions
among 18 participants in a natural, indoor environment for over 60 minutes,
under the poster presentation and cocktail party contexts presenting
difficulties in the form of low-resolution images, lighting variations,
numerous occlusions, reverberations and interfering sound sources; (2) To
alleviate these problems we facilitate multimodal analysis by recording the
social interplay using four static surveillance cameras and sociometric badges
worn by each participant, comprising the microphone, accelerometer, bluetooth
and infrared sensors. In addition to raw data, we also provide annotations
concerning individuals' personality as well as their position, head, body
orientation and F-formation information over the entire event duration. Through
extensive experiments with state-of-the-art approaches, we show (a) the
limitations of current methods and (b) how the recorded multiple cues
synergetically aid automatic analysis of social interactions. SALSA is
available at http://tev.fbk.eu/salsa.Comment: 14 pages, 11 figure
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