## 2 Overview of Research Directions Based on the Special Issue Papers  
The main content and results of the articles published in the Special Issue are summarised below. According to [PERSON] et al. [31], several factors play a role in the construction of virtual systems, and they also have a certain influence on test completion times. It can be seen that the test completion time increases most often when the user uses the Gear VR display and a contrast ratio of 7:1 is found in the virtual environment. Thanks to the results, more precise time limits can be set for future virtual reality-based spatial perception tests, depending on the structure of the virtual environment. This is sufficiently important in engineering education. [PERSON] et al. [32] provide a biologically based computing model that can endow autonomous unmanned vehicles with cognitive abilities such as continuous perception and exploration of the environment. The results of the performed experiments show that the Visuospatial Working Memory (VSWM) computational model proposed in this paper can maintain the coherent and continuous representation of visual and spatial relationships between objects of interest presented in the environment even when the visual stimulus is lost. [PERSON] et al. [33] provide a new adaptive methodology for thermal control based on an occupant's activity, using computer vision for action recognition together with a thermal comfort fuzzy control system. During the research, deep learning and fuzzy logic techniques were used, as they provide both great performance and explainability. An adaptive context-aware fuzzy temperature control system was recommended to adjust heat settings according to the occupants' actions. The aim of this research is to improve the traditional thermal model by presenting an adaptive method. According to [PERSON] et al. [34] augmented reality makes it possible for activities such as presentations, training or therapy to take place in virtual reality. In order to make online augmented reality available to as many people as possible, solutions have been created that can run directly in the web browser. One of the most recognised solutions is the A-Frame framework developed by the Mozilla VR team, which supports most of the hardware used in augmented reality. Additionally, an extension Networked-Aframe allows multiple users to share virtual environments created with A-Frame in real time. Thispaper presents and evaluates three components that extend the functionality of A-Frame and Networked-Aframe. The first extends Networked-Aframe with the ability to monitor and control users in a shared virtual scene. The second implements six-degree-of-freedom motion tracking for smartphone-based virtual reality headsets. The third provides gesture support for the Microsoft HoloLens holographic computer. [PERSON] et al. [35] examine user performance in a hybrid spectrum access model in a large cognitive radio network (CRN), where multiple primary users (PUs) and secondary users (SUs) broadcast simultaneously on the same channel. SUs first detect the channel state by channel sensing, and based on the channel sensing result, select the appropriate channel access scheme (or underlay or overlay) for their transmissions. When at least one PU is active, the SUs transmit according to the down-channel access scheme using the power control technique to ensure that the interference generated in the primary network is below the predetermined interference threshold. In the absence of a PU, the SUs transmit at full transmission power according to the overlay channel access scheme, thereby maximizing their transmission rate. Follow-up analyses using the tool of stochastic geometry were determined on important metrics such as the probability of success, throughput and average age of information (AoI) in both primary and secondary networks, while the interference between the two networks was recorded.