Vedran Mrzljak

Dr. Vedran Mrzljak

Faculty of Engineering, University of Rijeka
orcid

Research Focus & Metrics

Academic Career Length

11Years (2016-Present)

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

Representative Publications

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29 May 2020 in Computational and Mathematical Methods in Medicine
Verified
Journal Article
Open access
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Zlatan CarZlatan Car
Zlatan Car
Sandi Baressi ŠegotaSandi Baressi Šegota
Sandi Baressi Šegota
Nikola AnđelićNikola Anđelić
Nikola Anđelić
Ivan LorencinIvan Lorencin
Ivan Lorencin
Vedran MrzljakVedran Mrzljak
Vedran Mrzljak
Coronavirus (COVID-19) is a highly infectious disease that has captured the attention of the worldwide public. Modeling of such diseases can be extremely important in the prediction of their impact. While classic, statistical, modeling can provide satisfactory models, it can also fail to comprehend the intricacies contained within the data. In this paper, authors use a publicly available dataset, containing information on infected, recovered, and deceased patients in 406 locations over 51 days (22nd January 2020 to 12th March 2020). This dataset, intended to be a time-series dataset, is transformed into a regression dataset and used in training a multilayer perceptron (MLP) artificial neural network (ANN). The aim of training is to achieve a worldwide model of the maximal number of patients across all locations in each time unit. Hyperparameters of the MLP are varied using a grid search algorithm, with a total of 5376 hyperparameter combinations. Using those combinations, a total of 48384 ANNs are trained (16128 for each patient group—deceased, recovered, and infected), and each model is evaluated using the coefficient of determination (R2). Cross-validation is performed using K-fold algorithm with 5-folds. Best models achieved consists of 4 hidden layers with 4 neurons in each of those layers, and use a ReLU activation function, with R2 scores of 0.98599 for confirmed, 0.99429 for deceased, and 0.97941 for recovered patient models. When cross-validation is performed, these scores drop to 0.94 for confirmed, 0.781 for recovered, and 0.986 for deceased patient models, showing high robustness of the deceased patient model, good robustness for confirmed, and low robustness for recovered patient model.

15 November 2019 in Energies
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Journal Article
Open access
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Ivan LorencinIvan Lorencin
Ivan Lorencin
Nikola AnđelićNikola Anđelić
Nikola Anđelić
Vedran MrzljakVedran Mrzljak
Vedran Mrzljak
Zlatan CarZlatan Car
Zlatan Car
In this paper a genetic algorithm (GA) approach to design of multi-layer perceptron (MLP) for combined cycle power plant power output estimation is presented. Dataset used in this research is a part of publicly available UCI Machine Learning Repository and it consists of 9568 data points (power plant operating regimes) that is divided on training dataset that consists of 7500 data points and testing dataset containing 2068 data points. Presented research was performed with aim of increasing regression performances of MLP in comparison to ones available in the literature by utilizing heuristic algorithm. The GA described in this paper is performed by using mutation and crossover procedures. These procedures are utilized for design of 20 different chromosomes in 50 different generations. MLP configurations that are designed with GA implementation are validated by using Bland - Altman (B-A) analysis. By utilizing GA, MLP with five hidden layers of 80,25,65,75 and 80 nodes, respectively, is designed. For aforementioned MLP, k - fold cross-validation is performed in order to examine its generalization performances. The Root Mean Square Error ( R M S E ) value achieved with aforementioned MLP is 4.305 , that is significantly lower in comparison with MLP presented in available literature, but still higher than several complex algorithms such as KStar and tree based algorithms.


1 July 2021 in International Journal of Advanced Robotic Systems
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Journal Article
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SŠSandi Baressi Šegota
Sandi Baressi Šegota
NANikola Anđelić
Nikola Anđelić
Vedran MrzljakVedran Mrzljak
Vedran Mrzljak
ILIvan Lorencin
Ivan Lorencin
IKIvan Kuric
Ivan Kuric
Zlatan CarZlatan Car
Zlatan Car
Inverse kinematic equations allow the determination of the joint angles necessary for the robotic manipulator to place a tool into a predefined position. Determining this equation is vital but a complex work. In this article, an artificial neural network, more specifically, a feed-forward type, multilayer perceptron (MLP), is trained, so that it could be used to calculate the inverse kinematics for a robotic manipulator. First, direct kinematics of a robotic manipulator are determined using Denavit–Hartenberg method and a dataset of 15,000 points is generated using the calculated homogenous transformation matrices. Following that, multiple MLPs are trained with 10,240 different hyperparameter combinations to find the best. Each trained MLP is evaluated using the R 2 and mean absolute error metrics and the architectures of the MLPs that achieved the best results are presented. Results show a successful regression for the first five joints (percentage error being less than 0.1%) but a comparatively poor regression for the final joint due to the configuration of the robotic manipulator.

1 June 2017 in Applied Thermal Engineering
Verified
Journal Article
Closed access
Vedran MrzljakVedran Mrzljak
Vedran Mrzljak
Igor PoljakIgor Poljak
Igor Poljak
VMVedran Medica-Viola
Vedran Medica-Viola