Abstract

Abstract
Network comparison is a widely used tool for analysing complex systems, with applications in varied domains including comparison of protein interactions or highlighting changes in structure of trade networks. In recent years, a number of network comparison methodologies based on the distribution of graphlets (small connected network subgraphs) have been introduced. In particular, NetEmd has recently achieved state of the art performance in undirected networks. In this work, we propose an extension of NetEmd to directed networks and deal with the significant increase in complexity of graphlet structure in the directed case by denoising through linear projections. Simulation results show that our framework is able to improve on the performance of a simple translation of the undirected NetEmd algorithm to the directed case, especially when networks differ in size and density.

Abstract
Nowadays, the consumption of media content has been growing rapidly and consistently, driven by an easy access to Video on Demand platforms. In this context, licensing is needed to ensure that filmmakers receive rightful payment for their content and ensure that their rights as content owners are respected. The traditional licensing process, which is heavily dependent on third parties (legal entities) to mediate the transaction, is very long, costly, and complex, which is a barrier to smaller independent filmmakers. The solution proposed in this work, to address this problem, is to create a business-to-business marketplace platform supported by a Blockchain licensing module. This module takes advantage of Blockchain technology to ensure the licensing requirements and to provide a secure, practical and straightforward way to license media in a decentralised paradigm. The result of this work was validated though a prototype, and a global assessment of the system's usability was performed using the System Usability Scale, where it got the best possible grade.

Abstract

Abstract

Abstract
Currently, it is standard to use tracked handheld controllers for interaction in immersive virtual reality (VR). However, since VR interactions are becoming more natural with hand tracking, it is important to provide hands-free alternatives for selection and system control tasks. As such, this study aims to provide an exploratory evaluation of the effectiveness and efficiency of commonly used hands-free interfaces in selection and system control tasks. Nine interaction methods were evaluated while performing a Fitts' law task with nine advanced users of VR in a within-subject experiment. We evaluated handheld controllers as a baseline, against head gaze, eye gaze, and voice commands for pointing at the targets, and dwell time and voice commands to confirm selections. We found that using eye gaze with a 500 ms dwell time proved to be the hand-free method with the highest performance, matching the handheld controllers and being preferred by users. The evaluation also showed that using a multimodal approach to selection, especially using the voice, decreases performance, but increases effectiveness. Moreover, we verified that Fitts' law can be applied to hands-free methods, but its usage is limited when the methods have very short travel times. We then suggest selections per minute as a more robust comparative performance metric. Further studies should expand the audience and interaction tasks and focus on the confirmatory method of selection.