1,290 research outputs found
Learning fuzzy systems: an ojective function-approach
One of the most important aspects of fuzzy systems is that they are
easily understandable and interpretable. This property, however, does not
come for free but poses some essential constraints on the parameters of a
fuzzy system (like the linguistic terms), which are sometimes overlooked when
learning fuzzy system automatically from data. In this paper, an objective
function-based approach to learn fuzzy systems is developed, taking these
constraints explicitly into account. Starting from fuzzy c-means clustering,
several modifications of the basic algorithm are proposed, affecting the shape
of the membership functions, the partition of individual variables and the
coupling of input space partitioning and local function approximation
Online Modeling and Monitoring of Dependent Processes under Resource Constraints
Adaptive monitoring of a large population of dynamic processes is critical
for the timely detection of abnormal events under limited resources in many
healthcare and engineering systems. Examples include the risk-based disease
screening and condition-based process monitoring. However, existing adaptive
monitoring models either ignore the dependency among processes or overlook the
uncertainty in process modeling. To design an optimal monitoring strategy that
accurately monitors the processes with poor health conditions and actively
collects information for uncertainty reduction, a novel online collaborative
learning method is proposed in this study. The proposed method designs a
collaborative learning-based upper confidence bound (CL-UCB) algorithm to
optimally balance the exploitation and exploration of dependent processes under
limited resources. Efficiency of the proposed method is demonstrated through
theoretical analysis, simulation studies and an empirical study of adaptive
cognitive monitoring in Alzheimer's disease
Model-Based Clustering and Classification of Functional Data
The problem of complex data analysis is a central topic of modern statistical
science and learning systems and is becoming of broader interest with the
increasing prevalence of high-dimensional data. The challenge is to develop
statistical models and autonomous algorithms that are able to acquire knowledge
from raw data for exploratory analysis, which can be achieved through
clustering techniques or to make predictions of future data via classification
(i.e., discriminant analysis) techniques. Latent data models, including mixture
model-based approaches are one of the most popular and successful approaches in
both the unsupervised context (i.e., clustering) and the supervised one (i.e,
classification or discrimination). Although traditionally tools of multivariate
analysis, they are growing in popularity when considered in the framework of
functional data analysis (FDA). FDA is the data analysis paradigm in which the
individual data units are functions (e.g., curves, surfaces), rather than
simple vectors. In many areas of application, the analyzed data are indeed
often available in the form of discretized values of functions or curves (e.g.,
time series, waveforms) and surfaces (e.g., 2d-images, spatio-temporal data).
This functional aspect of the data adds additional difficulties compared to the
case of a classical multivariate (non-functional) data analysis. We review and
present approaches for model-based clustering and classification of functional
data. We derive well-established statistical models along with efficient
algorithmic tools to address problems regarding the clustering and the
classification of these high-dimensional data, including their heterogeneity,
missing information, and dynamical hidden structure. The presented models and
algorithms are illustrated on real-world functional data analysis problems from
several application area
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