Wyniki wyszukiwania - BazTech

1

Automatic identification of dysphonias using machine learning algorithms

Bello-Rivera Miguel Angel, Reyes-García Carlos Alberto, Talavera-Rojas Tania Cristal, Quintero-Flores Perfecto Malaquías, Pérez-Loaiza Rodolfo Eleazar

Applied Computer Science

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2023

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Vol. 19, no 4

14--25

EN

Dysphonia is a prevalent symptom of some respiratory diseases that affects voice quality, even for prolonged periods. For its diagnosis, speech-language pathologists make use of different acoustic parameters to perform objective evaluations on patients and determine the type of dysphonia that affects them, such as hyperfunctional and hypofunctional dysphonia, which is important because each type requires a different treatment. In the field of artificial intelligence this problem has been addressed through the use of acoustic parameters that are used as input data to train machine learning and deep learning models. However, its purpose is usually to identify whether a patient is ill or not, making binary classifications between healthy voices and voices with dysphonia, but not between dysphonias. In this paper, harmonic-to-noise ratio, cepstral peak prominence-smoothed, zero crossing rate and the means of the Mel frequency cepstral coefficients (2-19) are used to make multiclass classification of voices with euphony, hyperfunction and hypofunction by means of six machine learning algorithms, which are: Random Forest, K nearest neighbors, Logistic regression, Decision trees, Support vector machines and Naive Bayes. In order to evaluate which of them presents a better performance to identify the three voice classes, bootstrap.632 was used. It is concluded that the best confidence interval ranges from 87% to 92%, in terms of accuracy for the K Nearest Neighbors model. Results can be implemented in the development of a complementary application for the clinical diagnosis or monitoring of a patient under the supervision of a specialist.

2

Multiclass skin lessions classification based on deep neural networks

Michalska-Ciekańska Magdalena

Informatyka, Automatyka, Pomiary w Gospodarce i Ochronie Środowiska

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2022

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T. 12, nr 2

10--14

EN

Skin diseases diagnosed with dermatoscopy are becoming more and more common. The use of computerized diagnostic systems becomes extremely effective. Non-invasive methods of diagnostics, such as deep neural networks, are an increasingly common tool studied by scientists. The article presents an overview of selected main issues related to the multi-class classification process: the stage of database selection, initial image processing, selection of the learning data set, classification tools, network training stage and obtaining final results. The described actions were implemented using available deep neural networks. The article pay attention to the final results of available models, such as effectiveness, specificity, classification accuracy for different numbers of classes and available data sets.

PL

Choroby skóry diagnozowane za pomocą dermatoskopii są coraz powszechniejsze. Wykorzystanie skomputeryzowanych systemów diagnostyki staje się niezwykle skuteczne. Nieinwazyjne metody diagnostyki, jakimi są głębokie sieci neuronowe są coraz powszechniejszym narzędziem badanym przez naukowców. W artykule przedstawiono przegląd wybranych głównych zagadnień związanych w procesem klasyfikacji wieloklasowej: etap wyboru bazy danych, wstępnego przetwarzania obrazów, doboru zestawu danych uczących, narzędzi klasyfikacji, etapu trenowania sieci i otrzymania wyników końcowych. Opisane działania zostały zaimplementowane za pomocą dostępnych głębokich sieci neuronowych. W artykule zwrócono uwagę na wyniki końcowe dostępnych modeli, takich jak skuteczność, specyficzność, dokładność klasyfikacji dla różnej ilości klas i dostępnych zestawów danych.

3

Drought classification using gradient boosting decision tree

Danandeh Mehr Ali

Acta Geophysica

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2021

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Vol. 69, no. 3

909--918

EN

This paper compares the classification and prediction capabilities of decision tree (DT), genetic programming (GP), and gradient boosting decision tree (GBT) techniques for one-month ahead prediction of standardized precipitation index in Ankara province and standardized precipitation evaporation index in central Antalya region. The evolved models were developed based on multi-station prediction scenarios in which observed (reanalyzed) data from nearby stations (grid points) were used to predict drought conditions in a target location. To tackle the rare occurrence of extreme dry/wet conditions, the drought series at the target location was categorized into three classes of wet, normal, and dry events. The new models were trained and validated using the frst 70% and last 30% of the datasets, respectively. The results demonstrated the promising performance of GBT for meteorological drought classification. It provides better performance than DT and GP in Ankara; however, GP predictions for Antalya were more accurate in the testing period. The results also exhibited that the proposed GP model with a scaled sigmoid function at root can efortlessly classify and predict the number of dry, normal, and wet events in both case studies.

4

Using the one-versus-rest strategy with samples balancing to improve pairwise coupling classification

Chmielnicki W., Stąpor K.

International Journal of Applied Mathematics and Computer Science

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2016

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Vol. 26, no. 1

191--201

EN

The simplest classification task is to divide a set of objects into two classes, but most of the problems we find in real life applications are multi-class. There are many methods of decomposing such a task into a set of smaller classification problems involving two classes only. Among the methods, pairwise coupling proposed by Hastie and Tibshirani (1998) is one of the best known. Its principle is to separate each pair of classes ignoring the remaining ones. Then all objects are tested against these classifiers and a voting scheme is applied using pairwise class probability estimates in a joint probability estimate for all classes. A closer look at the pairwise strategy shows the problem which impacts the final result. Each binary classifier votes for each object even if it does not belong to one of the two classes which it is trained on. This problem is addressed in our strategy. We propose to use additional classifiers to select the objects which will be considered by the pairwise classifiers. A similar solution was proposed by Moreira and Mayoraz (1998), but they use classifiers which are biased according to imbalance in the number of samples representing classes.

5

Stability of gene selection methods for multiclass clssification

Student S., Fujarewicz K.

Journal of Medical Informatics & Technologies

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2010

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Vol. 15

101--107

EN

A big problem in applying DNA microarrays for classification is dimension of the dataset. Recently we proposed a gene selection method based on Partial Least Squares (PLS) for searching best genes for classification. The new idea is to use PLS not only as multiclass approach, but to construct more binary selections that use one versus rest and one versus one approaches. Ranked gene lists are highly instable in the sense, that a small change of the data set often leads to big change of the obtained ordered list. In this article, we take a look at the assessment of stability of our approaches. We compare the variability of the obtained ordered lists from proposed methods with well known Recursive Feature Elimination (RFE) method and classical t-test method. This paper focuses on effective identification of informative genes. As a result, a new strategy to find small subset of significant genes is designed. Our results on real cancer data show that our approach has very high accuracy rate for different combinations of classification methods giving in the same time very stable feature rankings.