Riku Klén

Dr. Riku Klén

University of Turku, Turku, Varsinais-Suomi, Finland
+1
orcid

Research Focus & Metrics

Academic Career Length

19Years (2008-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

View All Publications
13 March 2024 in Scientific Reports
Verified
Journal Article
Open access
PDF file
OROona Rainio
Oona Rainio
JTJarmo Teuho
Jarmo Teuho
Riku KlénRiku Klén
Riku Klén
Research on different machine learning (ML) has become incredibly popular during the past few decades. However, for some researchers not familiar with statistics, it might be difficult to understand how to evaluate the performance of ML models and compare them with each other. Here, we introduce the most common evaluation metrics used for the typical supervised ML tasks including binary, multi-class, and multi-label classification, regression, image segmentation, object detection, and information retrieval. We explain how to choose a suitable statistical test for comparing models, how to obtain enough values of the metric for testing, and how to perform the test and interpret its results. We also present a few practical examples about comparing convolutional neural networks used to classify X-rays with different lung infections and detect cancer tumors in positron emission tomography images.

1 September 2016 in Nonlinear Analysis
Verified
Journal Article
Closed access
PHPetteri Harjulehto
Petteri Harjulehto
PHPeter Hästö
Peter Hästö
Riku KlénRiku Klén
Riku Klén

1 January 2015 in Annales Academiae Scientiarum Fennicae Mathematica
Verified
Journal Article
Closed access
JCJiaolong Chen
Jiaolong Chen
PHParisa Hariri
Parisa Hariri
Riku KlénRiku Klén
Riku Klén
MVMatti Vuorinen
Matti Vuorinen
The triangular ratio metric is studied in subdomains of the complex plane and Euclidean $n$-space. Various inequalities are proven for it. The main results deal with the behavior of this metric under quasiconformal maps. We also study the smoothness of metric disks with small radii.Comment: 30 pages, four figure

1 January 2010 in Journal of Inequalities and Applications
Verified
Journal Article
Open access
PDF file
Riku KlénRiku Klén
Riku Klén
MVM Visuri
M Visuri
MVM Vuorinen
M Vuorinen
This paper deals with some inequalities for trigonometric and hyperbolic functions such as the Jordan inequality and its generalizations. In particular, lower and upper bounds for functions such as and are proved.

27 April 2023 in Journal of Digital Imaging
Verified
Journal Article
Open access
PDF file
OROona Rainio
Oona Rainio
CHChunlei Han
Chunlei Han
JTJarmo Teuho
Jarmo Teuho
SNSergey V. Nesterov
Sergey V. Nesterov
VOVesa Oikonen
Vesa Oikonen
Riku KlénRiku Klén
Riku Klén
Carimas is a multi-purpose medical imaging data processing tool, which can be used to visualize, analyze, and model different medical images in research. Originally, it was developed only for positron emission tomography data in 2009, but the use of this software has extended to many other tomography imaging modalities, such as computed tomography and magnetic resonance imaging. Carimas is especially well-suited for analysis of three- and four-dimensional image data and creating polar maps in modeling of cardiac perfusion. This article explores various parts of Carimas, including its key features, program structure, and application possibilities.

1 June 2008 in Journal of Mathematical Analysis and Applications
Verified
Journal Article
Closed access
Riku KlénRiku Klén
Riku Klén