Wyniki wyszukiwania - BazTech

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Extraction of fuzzy rules at different concept levels related to image features of mammography for diagnosis of breast cancer

Goudarzi M., Maghooli K.

Biocybernetics and Biomedical Engineering

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2018

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Vol. 38, no. 4

1004--1014

EN

Mammography is an inexpensive and non-invasive method through which one can diagnose breast cancer in its early stages. As these images need interpretation by a radiologist, this may develop some problems due to fatigue, repetition, and need for a great deal of attention to details and other factors. Thus, a method capable of diagnosing breast cancer should be employed to help physicians in this regard. In this paper, The mini Mammographic Image Analysis Society (mini-MIAS) database of mammograms is used. The aim is to distinguish between normal and abnormal classes. In the preprocessing stage, noise removal, removal of labels of images, heightening the contrast, and ROI segmentation are performed, and then compactness, entropy, mean, and smoothness are extracted from the images. In addition to classification, we have come to a new approach in order to create a complete knowledge base, which then we use this knowledge base for classification. We have a comprehensive knowledge base which covers all the conceptual levels. The extracted features are referred to as fuzzy classifiers through the look-up table method. And, for evaluation of the results, the 10-fold method is used. Discretization operations are performed on training data across 2, 3, and 4 levels to develop concept hierarchy. Concept hierarchies reduce the data by replacing low-level concepts with higher-level concepts and the outcome is more meaningful and easier to interpret. Eventually, Bagging algorithm is used for finding out the majority vote and the final result of the discretization levels. The obtained accuracy is 89.37 ± 6.62.

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Predictive and look-up table control methods of a three-level AC-DC converter under distorted grid voltage

Falkowski P., Kulikowski K., Grodzki R.

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2017

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Vol. 65, nr 5

609--618

EN

Power electronic three-level AC-DC converters connecting a utility grid with DC supplies are widely used in renewable energy sources. For such distributed systems, the quality of energy is very important. Hence, control algorithms of an AC-DC converter have to provide not only a sinusoidal shape of grid current, but also stable operation during transient states in the grid, e.g. voltage dips or voltage unbalance. This paper deals with the problem of robustness of AC-DC control methods under disturbed grid voltage. Three modern predictive control algorithms are presented and investigated under grid voltage distortions. Experimental results from a laboratory test setup illustrating properties of the described methods are shown.

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Nonlinear inverse solution by the look-up table method for Risley-prism-based scanner

Li A., Sun W., Gao X.

Optica Applicata

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2016

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Vol. 46, nr 4

501--515

EN

A pair of rotation Risley prisms can perform superior optical pointing and tracking functions with large visual field and high accuracy. Crucial to the function implementation are the nonlinear inverse solutions to the double-prism orientation angles for tracking a given target trajectory. In the paper, a novel look-up table method is proposed to solve this problem. Because there are two groups of solutions to the rotation angles achieved from an arbitrary target point, a "jump" phenomenon occurs and generates the discontinuous curves of multi-group rotation angle solutions. According to the mapping relation between the coordinate values of the target point and the corresponding rotation angles of two prisms, we can establish the continuous solution curves by adding constraints and employing an optimization algorithm. Experimental results validate the obtained inverse solutions applicable to scan a trajectory close to the given one within an error threshold. The proposed look-up table method can provide foundation for the continuous control of the Risley-prism-based scanner in its inverse applications.Keywords: Risley prism, look-up table method, inverse solution, scanner.