189,871 research outputs found

    Applied sensor fault detection and identification during steady-state and transient system operation

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    The paper presents two readily implementable methods for sensor fault detection and identification (SFD/I) for complex systems. Specifically, principal component analysis (PCA) and self-organizing map neural network (SOMNN) based algorithms are demonstrated for use on industrial gas turbine (IGT) systems. Two operational regimes are considered viz. steady-state operation and operation during transient conditions. For steady-state operation, PCA based squared prediction error (SPE) is used for SFD, and through the use of contribution plots, SFI. For SFD/I under operational conditions with transients, a proposed ‘y-index’ is introduced based on PCA with transposed input matrix that provides information on anomalies in the sensor domain (rather than in the time domain as with the traditional PCA approach). Moreover, using a SOMNN approach, during steady-state operation the estimation error (EE) is used for SFD and EE contribution plots for SFI. Additionally, during transient operation, SOMNN classification maps (CMs) are used through comparisons with ‘fingerprints’ taken during normal operation. Validation of the approaches is demonstrated through experimental trial data taken during the commissioning of IGTs. Although the attributes of the techniques are focused on a particular industrial sector in this case, ultimately their use is expected to be much more widely applicable to other fields and systems

    Clustering Of Complex Shaped Data Sets Via Kohonen Maps And Mathematical Morphology

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    Clustering is the process of discovering groups within the data, based on similarities, with a minimal, if any, knowledge of their structure. The self-organizing (or Kohonen) map (SOM) is one of the best known neural network algorithms. It has been widely studied as a software tool for visualization of high-dimensional data. Important features include information compression while preserving topological and metric relationship of the primary data items. Although Kohonen maps had been applied for clustering data, usually the researcher sets the number of neurons equal to the expected number of clusters, or manually segments a two-dimensional map using some a priori knowledge of the data. This paper proposes techniques for automatic partitioning and labeling SOM networks in clusters of neurons that may be used to represent the data clusters. Mathematical morphology operations, such as watershed, are performed on the U-matrix, which is a neuron-distance image. The direct application of watershed leads to an oversegmented image. It is used markers to identify significant clusters and homotopy modification to suppress the others. Markers are automatically found by performing a multi-level scan of connected regions of the U-matrix. Each cluster of neurons is a sub-graph that defines, in the input space, complex and nonparametric geometries which approximately describes the shape of the clusters. The process of map partitioning is extended recursively. Each cluster of neurons gives rise to a new map, which are trained with the subset of data that were classified to it. The algorithm produces dynamically a hierarchical tree of maps, which explains the cluster's structure in levels of granularity. The distributed and multiple prototypes cluster representation enables the discoveries of clusters even in the case when we have two or more non-separable pattern classes.43841627Vinod, V.V., Chaudhury, S., Mukherjee, J., Ghose, S., A connectionist approach for clustering with applications in image analysis (1994) IEEE Trans. Systems, Man & Cybernetics, 24 (3), pp. 356-384Costa, J.A.F., (1999) Automatic classification and data analysis by self-organizing neural networks, , Ph.D. Thesis. State University of Campinas, SP, BrazilEveritt, B.S., (1993) Cluster Analysis, , Wiley: New YorkKaufman, L., Rousseeuw, P., (1990) Finding Groups in Data: An Introduction to Cluster Analysis, , Wiley: New YorkSu, M.-C., Declaris, N., Liu, T.-K., Application of neural networks in cluster analysis (1997) Proc. of the 1997 IEEE Intl. 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    EMERGING THE EMERGENCE SOCIOLOGY: The Philosophical Framework of Agent-Based Social Studies

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    The structuration theory originally provided by Anthony Giddens and the advance improvement of the theory has been trying to solve the dilemma came up in the epistemological aspects of the social sciences and humanity. Social scientists apparently have to choose whether they are too sociological or too psychological. Nonetheless, in the works of the classical sociologist, Emile Durkheim, this thing has been stated long time ago. The usage of some models to construct the bottom-up theories has followed the vast of computational technology. This model is well known as the agent based modeling. This paper is giving a philosophical perspective of the agent-based social sciences, as the sociology to cope the emergent factors coming up in the sociological analysis. The framework is made by using the artificial neural network model to show how the emergent phenomena came from the complex system. Understanding the society has self-organizing (autopoietic) properties, the Kohonen’s self-organizing map is used in the paper. By the simulation examples, it can be seen obviously that the emergent phenomena in social system are seen by the sociologist apart from the qualitative framework on the atomistic sociology. In the end of the paper, it is clear that the emergence sociology is needed for sharpening the sociological analysis in the emergence sociology

    Analysis of Data Clusters Obtained by Self-Organizing Methods

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    The self-organizing methods were used for the investigation of financial market. As an example we consider data time-series of Dow Jones index for the years 2002-2003 (R. Mantegna, cond-mat/9802256). In order to reveal new structures in stock market behavior of the companies drawing up Dow Jones index we apply SOM (Self-Organizing Maps) and GMDH (Group Method of Data Handling) algorithms. Using SOM techniques we obtain SOM-maps that establish a new relationship in market structure. Analysis of the obtained clusters was made by GMDH.Comment: 10 pages, 4 figure

    How Many Dissimilarity/Kernel Self Organizing Map Variants Do We Need?

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    In numerous applicative contexts, data are too rich and too complex to be represented by numerical vectors. A general approach to extend machine learning and data mining techniques to such data is to really on a dissimilarity or on a kernel that measures how different or similar two objects are. This approach has been used to define several variants of the Self Organizing Map (SOM). This paper reviews those variants in using a common set of notations in order to outline differences and similarities between them. It discusses the advantages and drawbacks of the variants, as well as the actual relevance of the dissimilarity/kernel SOM for practical applications

    Seven properties of self-organization in the human brain

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    The principle of self-organization has acquired a fundamental significance in the newly emerging field of computational philosophy. Self-organizing systems have been described in various domains in science and philosophy including physics, neuroscience, biology and medicine, ecology, and sociology. While system architecture and their general purpose may depend on domain-specific concepts and definitions, there are (at least) seven key properties of self-organization clearly identified in brain systems: 1) modular connectivity, 2) unsupervised learning, 3) adaptive ability, 4) functional resiliency, 5) functional plasticity, 6) from-local-to-global functional organization, and 7) dynamic system growth. These are defined here in the light of insight from neurobiology, cognitive neuroscience and Adaptive Resonance Theory (ART), and physics to show that self-organization achieves stability and functional plasticity while minimizing structural system complexity. A specific example informed by empirical research is discussed to illustrate how modularity, adaptive learning, and dynamic network growth enable stable yet plastic somatosensory representation for human grip force control. Implications for the design of “strong” artificial intelligence in robotics are brought forward
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