6,724 research outputs found
Hyperspectral Unmixing Overview: Geometrical, Statistical, and Sparse Regression-Based Approaches
Imaging spectrometers measure electromagnetic energy scattered in their
instantaneous field view in hundreds or thousands of spectral channels with
higher spectral resolution than multispectral cameras. Imaging spectrometers
are therefore often referred to as hyperspectral cameras (HSCs). Higher
spectral resolution enables material identification via spectroscopic analysis,
which facilitates countless applications that require identifying materials in
scenarios unsuitable for classical spectroscopic analysis. Due to low spatial
resolution of HSCs, microscopic material mixing, and multiple scattering,
spectra measured by HSCs are mixtures of spectra of materials in a scene. Thus,
accurate estimation requires unmixing. Pixels are assumed to be mixtures of a
few materials, called endmembers. Unmixing involves estimating all or some of:
the number of endmembers, their spectral signatures, and their abundances at
each pixel. Unmixing is a challenging, ill-posed inverse problem because of
model inaccuracies, observation noise, environmental conditions, endmember
variability, and data set size. Researchers have devised and investigated many
models searching for robust, stable, tractable, and accurate unmixing
algorithms. This paper presents an overview of unmixing methods from the time
of Keshava and Mustard's unmixing tutorial [1] to the present. Mixing models
are first discussed. Signal-subspace, geometrical, statistical, sparsity-based,
and spatial-contextual unmixing algorithms are described. Mathematical problems
and potential solutions are described. Algorithm characteristics are
illustrated experimentally.Comment: This work has been accepted for publication in IEEE Journal of
Selected Topics in Applied Earth Observations and Remote Sensin
A novel method for anomaly detection using beta hebbian learning and principal component analysis
In this research work a novel two-step system for anomaly detection is presented and tested over several real datasets. In the first step the novel Exploratory Projection Pursuit, Beta Hebbian Learning algorithm, is applied over each dataset, either to reduce the dimensionality of the original dataset or to face nonlinear datasets by generating a new subspace of the original dataset with lower, or even higher, dimensionality selecting the right activation function. Finally, in the second step Principal Component Analysis anomaly detection is applied to the new subspace to detect the anomalies and improve its classification capabilities. This new approach has been tested over several different real datasets, in terms of number of variables, number of samples and number of anomalies. In almost all cases, the novel approach obtained better results in terms of area under the curve with similar standard deviation values. In case of computational cost, this improvement is only remarkable when complexity of the dataset in terms of number of variables is high.CITIC, as a Research Center of the University System of Galicia, is funded by Consellería de Educación, Universidade e Formación Profesional of the Xunta de Galicia through the European Regional Development Fund and the Secretaría Xeral de Universidades (ref. ED431G 2019/01).info:eu-repo/semantics/publishedVersio
Crop Yield Prediction Using Deep Neural Networks
Crop yield is a highly complex trait determined by multiple factors such as
genotype, environment, and their interactions. Accurate yield prediction
requires fundamental understanding of the functional relationship between yield
and these interactive factors, and to reveal such relationship requires both
comprehensive datasets and powerful algorithms. In the 2018 Syngenta Crop
Challenge, Syngenta released several large datasets that recorded the genotype
and yield performances of 2,267 maize hybrids planted in 2,247 locations
between 2008 and 2016 and asked participants to predict the yield performance
in 2017. As one of the winning teams, we designed a deep neural network (DNN)
approach that took advantage of state-of-the-art modeling and solution
techniques. Our model was found to have a superior prediction accuracy, with a
root-mean-square-error (RMSE) being 12% of the average yield and 50% of the
standard deviation for the validation dataset using predicted weather data.
With perfect weather data, the RMSE would be reduced to 11% of the average
yield and 46% of the standard deviation. We also performed feature selection
based on the trained DNN model, which successfully decreased the dimension of
the input space without significant drop in the prediction accuracy. Our
computational results suggested that this model significantly outperformed
other popular methods such as Lasso, shallow neural networks (SNN), and
regression tree (RT). The results also revealed that environmental factors had
a greater effect on the crop yield than genotype.Comment: 9 pages, Presented at 2018 INFORMS Conference on Business Analytics
and Operations Research (Baltimore, MD, USA). One of the winning solutions to
the 2018 Syngenta Crop Challeng
A Decision-Making Tool Based on Exploratory Visualization for the Automotive Industry
In recent years, the digital transformation has been advancing in industrial companies,
supported by the Key Enabling Technologies (Big Data, IoT, etc.) of Industry 4.0. As a consequence,
companies have large volumes of data and information that must be analyzed to give them competitive
advantages. This is of the utmost importance in fields such as Failure Detection (FD) and Predictive
Maintenance (PdM). Finding patterns in such data is not easy, but cutting-edge technologies, such as
Machine Learning (ML), can make great contributions. As a solution, this study extends Hybrid
Unsupervised Exploratory Plots (HUEPs), as a visualization technique that combines Exploratory
Projection Pursuit (EPP) and Clustering methods. An extended formulation of HUEPs is proposed,
adding for the first time the following EPP methods: Classical Multidimensional Scaling, Sammon
Mapping and Factor Analysis. Extended HUEPs are validated in a case study associated with a
multinational company in the automotive industry sector. Two real-life datasets containing data
gathered from a Waterjet Cutting tool are visualized in an intuitive and informative way. The obtained
results show that HUEPs is a technique that supports the continuous monitoring of machines in order
to anticipate failures. This contribution to visual data analytics can help companies in decision-making,
regarding FD and PdM projects.The authors would like to thank the vehicle interiors manufacturer, Grupo Antolin, for its collaboration in this research
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