Štefan Korečko

This article presents L-NeRVEn, a software solution for after-stroke upper limb neurorehabilitation utilizing collaborative virtual reality (VR). L-NeRVEn offers a shared virtual environment, experienced via a VR headset, with animated full-body avatars representing both the therapist and the patient. The patient’s task is to imagine a particular movement with his or her disabled limb and the success of this imagination is determined by the processing and classification of the patient’s electroencephalography (EEG) signal. The EEG processing component is loosely coupled with the rest of the solution and can be easily modified or replaced. The article focuses on the architecture and appearance of L-NeRVEn, explains the role of its users, and the interaction of its components. It also presents the results of L-NeRVEn evaluation with n = 18 participants, utilizing subjective (SUS, IPQ and NASA-TLX questionnaires) and objective (video recordings and observer’s notes) methods.

The paper focuses on the measurement of PM and other meteorological parameters in a small region of central Europe—eastern Slovakia and northeastern Hungary. Due to the increasing availability of sensors measuring not only PM, but also temperature, humidity, pressure, VOC, NOx, and CO₂, new possibilities arise in terms of comparing (mainly in terms of correlation) PM and the other measured parameters, thus generating a large amount of data for evaluation. The correlations found are typical for inland conditions, thus able to map other regions of the world. The presented measurements can also be used to predict the evolution of PM with alerts for people with respiratory diseases, or in virtual reality using a digital twin of a humanoid robot.

Serious games are becoming a more commonly utilized tool in training, education, and learning. On the other hand, Petri nets, a well-known formalism for process modeling, seem to be a promising tool for describing learning activity scenarios for serious games and virtual environments. Thanks to their graphical form and easy-to-understand nature, it can be assumed that participants from different backgrounds should be able to understand and use Petri nets for their scenarios. A present study presented here investigates how this assumption corresponds to reality. In the study, a short explanation of Petri nets and a set of related tasks were given to a sample of 31 participants (n = 31). The participants were students of Computer Science (16) and Humanities (15). The results collected and statistically analyzed demonstrate both similarities and distinctions in the reactions to problem-solving assignments among individuals in the two groups. These findings and their analysis have been condensed and presented in visual form.

The technological advances we are witnessing today have stimulated the creation of many 3D virtual environments for various purposes, from entertainment to industry to education. While the majority of these environments are perfectly suited for the healthy population, we should not forget about impaired people living among us. Regarding children’s education, one may wonder how impaired children handle them. Do they find them usable and attractive? How well do they handle basic activities in 3D environments, including orientation and interaction with objects? The experiment presented in this article provides answers to these questions within a specific setup. The experiment used a custom web application with several 3D virtual environments in a desktop virtual reality setting. The participants were 12 children, aged 8–14, with multiple impairments, predominantly hearing impairment, borderline and mild degree of mental retardation, and inferior communication skills. The answers can be regarded as positive and are based on results gathered in the form of completion times and the System Usability Scale questionnaire scores. The article also reports on a significant relation found between completion times and questionnaire scores. Future research directions, including those related to the Metaverse concept, are discussed, too.

Technological advances in the field of virtual reality and personal computation in general brought usto the era of web-based virtual reality, where virtual environments can be accessed directly from webbrowsers and without the need of installation of any additional software. Such online virtualenvironments seem to be a promising tool for scientific data visualization. When accessed throughappropriate hardware, such as VR headsets, they also offer full immersion and isolation from externalinfluences. In this paper, we present a prototype solution for a histogram visualization in onlinevirtual environments. The prototype, named NDMVR, has been implemented using A-Frameframework for visualization, React.js for compositionality and JSROOT for histogram dataacquisition. Its user interface is primarily adjusted to personal computers and VR headsets.

The aim of the paper is to describe algorithms for automated Slovak words stacking, syntax readable for such algorithms and explain the need for these algorithms. Algorithm for Slovak nouns stacking serves to inflect all forms of Slovak nouns and together with designed syntax accelerate the process of writing them into system for sign language processing.