Virtual Interface Research Articles

Dynamic simulation model with virtual interfaces of supercritical working fluid heat exchanger based on moving boundary method

The supercritical cycle has a better variable-temperature match between the working fluid and heat source, potentially providing higher efficiency. Accurate simulation of the transient performance of supercritical heat exchangers is significant in advanced thermal system control. This paper proposes a dynamic model of supercritical heat exchangers based on the moving boundary method. The model redefines the concept of “interface” in the traditional moving boundary model. The new interfaces are determined by the thermophysical properties of the working fluid, called “virtual interfaces”. A control-volume separation method is proposed based on the virtual interface. Additionally, the specific enthalpy is selected as the switching criterion for the configuration of the control volumes, so the model can dynamically adjust the number of control volumes. The integrity check results show that the simulation accuracy is at least equivalent to the finite volume model with 20 control volumes; however, the time cost is approximately 1/5 of that of the finite volume model with the same precision. An experimental study on the convective heat transfer of supercritical n-decane in an electrically heated vertical tube was conducted. The maximum absolute error of the steady-state outlet temperature is ±1.5 K, and the relative error is ±3% under different pressures.

A Homogenization Approach for Turbulent Channel Flows over Porous Substrates: Formulation and Implementation of Effective Boundary Conditions

The turbulent flow through a plane channel bounded by a single permeable wall is considered; this is a problem of interest since a carefully chosen distribution of grains and voids in the porous medium can result in skin friction reduction for the flow in the channel. In the homogenization approach followed here, the flow is not resolved in the porous layer, but an effective velocity boundary condition is developed (and later enforced) at a virtual interface between the porous bed and the channel flow. The condition is valid up to order two in terms of a small gauge factor, the ratio of microscopic to macroscopic length scales; it contains slip coefficients, plus surface and bulk permeability coefficients, which arise from the solution of microscale problems solved in a representative elementary volume. Using the effective boundary conditions, free of empirical parameters, direct numerical simulations are then performed in the channel, considering a few different porous substrates. The results, examined in terms of mean values and turbulence statistics, demonstrate the drag-reducing effects of porous substrates with streamwise-preferential alignment of the solid grains.

The Effect of Virtual Human Rendering Style on User Perceptions of Visual Cues

Introduction: Virtual humans have expanded the training opportunities available to healthcare learners. Particularly, virtual humans have allowed simulation to display visual cues that were not previously possible in other forms of healthcare training. However, the effect of virtual human fidelity on the perception of visual cues is unclear. Therefore, we explore the effect of virtual human rendering style on the perceptions of visual cues in a healthcare context.Methods: To explore the effect of rendering style on visual cues, we created a virtual human interface that allows users to interact with virtual humans that feature different rendering styles. We performed a mixed design user study that had undergraduate healthcare students (n = 107) interact with a virtual patient. The interaction featured a patient experiencing an allergic reaction and required trainees to identify visual cues (patient symptoms). The rendering styles explored include a 3D modeled virtual human and an AI generated photorealistic virtual human. Visual cues were applied using a Snapchat Lens.Results: When users are given a frame of reference (users could directly compare symptoms on both rendering styles), they rated the realism and severity of the photorealistic virtual human’s symptoms significantly higher than the realism of the 3D virtual human’s symptoms. However, we were unable to find significant differences in symptom realism and severity ratings when users were not given a frame of reference (users only interacted with one style of virtual humans). Additionally, we were unable to find significant differences in user interpersonal communication behaviors between the 3D and photorealistic rendering styles.Conclusion: Our findings suggest 1) higher fidelity rendering styles may be preferred if the learning objectives of a simulation require observing subtle visual cues on virtual humans and 2) the realism of virtual human rendering style does not necessarily affect participants’ interpersonal communication behaviors (time spent, questions asked).

IEEE VR 2022 Introducing the Special Issue

Welcome to the 11 <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th IEEE Transactions on Visualization and Computer Graphics (TVCG)</i> special issue on IEEE Virtual Reality and 3D User Interfaces. This volume contains a total of 29 full papers selected for and presented at the IEEE Conference on Virtual Reality and 3D User Interfaces (IEEE VR 2022), held fully virtual in Christchurch, New Zealand from March 12 to 16, 2022.

Cross-VM Network Channel Attacks and Countermeasures Within Cloud Computing Environments

Cloud providers attempt to maintain the highest levels of isolation between Virtual Machines (VMs) and inter-user processes to keep co-located VMs and processes separate. This logical isolation creates an internal virtual network to separate VMs co-residing within a shared physical network. However, as co-residing VMs share their underlying VMM (Virtual Machine Monitor), virtual network, and hardware are susceptible to cross VM attacks. It is possible for a malicious VM to potentially access or control other VMs through network connections, shared memory, other shared resources, or by gaining the privilege level of its non-root machine. This research presents a two novel zero-day cross-VM network channel attacks. In the first attack, a malicious VM can redirect the network traffic of target VMs to a specific destination by impersonating the Virtual Network Interface Controller (VNIC). The malicious VM can extract the decrypted information from target VMs by using open source decryption tools such as Aircrack. The second contribution of this research is a privilege escalation attack in a cross VM cloud environment with Xen hypervisor. An adversary having limited privileges rights may execute Return-Oriented Programming (ROP), establish a connection with the root domain by exploiting the network channel, and acquiring the tool stack (root domain) which it is not authorized to access directly. Countermeasures against this attacks are also presented

IEEE VR 2022 Message from the Journal Paper Chairs and Guest Editors

In this special issue of <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">IEEE Transactions on Visualization and Computer Graphics</i> (TVCG), we are pleased to present a subset of papers from the 29th IEEE Conference on Virtual Reality and 3D User Interfaces (IEEE VR 2022), held virtually March 12-16, 2022, in Christchurch, New Zealand.

Participation of Soccer Training Improves Lower Limb Coordination and Decreases Motor Lateralization.

Athletes, who display less lateralization, are considered to be more successful in their sports. Therefore, it is important to test the lateralization profiles of the athletes to determine future prospects. Soccer is one of the sports where lateralization plays an important role because performing the passes and kicks with either foot may increase the success rate. Improved lower limb coordination is also very essential to perform the soccer skills more efficiently. Thus, the purpose of this study was to investigate the motor lateralization profiles of youth soccer players and to compare the same lateralization to non-athletes. A total of 28 healthy youth (14 soccer players) aged between 14 and 16 years voluntarily participated in this study. All participants were right-footed and were asked to hit the targets with their either foot maintaining accuracy in a custom-made virtual reality interface. Final position error (FPE) and foot path deviation from linearity (FPDL) were calculated to test motor lateralization for each foot and group. Two-way Mixed Model ANOVA was conducted for each dependent variable. Results indicated significant differences for FPDL between groups, while there were no significant differences between groups and within feet for FPE. Nonathletes had significantly higher FPDL with their nondominant foot compared to their dominant foot, which was not observed among soccer players. Overall, nonathletes' movements were more curvature path compared to soccer players, thus, can be considered as less coordinated. As soccer players did not show a difference between their feet on FPDL and performed better than nonathletes, soccer participation can improve lower limb coordination as well as alter motor performance and lateralization.

Electronic System for the Remote Monitoring of Solar Power Plant Parameters and Environmental Conditions

An electronic monitoring system was developed to monitor and analyze operating and environmental parameters of solar power plants. The electronic monitoring system consisted of two stages: the first stage was designed to receive data from temperature, illumination, voltage, electric current, and power sensors and modules; the second stage is for data collection, analysis, and display. Microcontrollers PIC18F25K22 (for data collection) and PIC24FV32KA302 (for data analysis and display) were used to implement the electronic monitoring system. RF module EBTYE OEM/ODM E32-433T20DC SX1278 433 MHz UART was used to transmit data to the central server. For the microcontrollers of both stages, original control program algorithms were developed, according to which program codes were written using the C programming language. Data were collected using the MySQL database. The virtual interface and application for displaying instant data were created using programming language Delphi. Data monitoring systems in the market have a number of shortcomings due to the difficulty of ensuring a centralized data management process. In addition, sensors used in most systems require a Wi-Fi Internet connection to transmit information, which is difficult to secure in remote solar parks. The aim of this work is to show that information transmission from individually deployed sensors to the central server can be ensured using the principle of RF communication, and data collection and analysis in a centralized way without additional costs for Wi-Fi networks in remote areas.

TelePhysicalOperation: Remote Robot Control Based on a Virtual “Marionette” Type Interaction Interface

Teleoperation permits to control robots from a safe distance while performing tasks in a remote environment. Kinematic differences between the input device and the remotely controlled manipulator or the existence of redundancy in the remote robot may pose challenges in moving intuitively the remote robot as desired by the human operator. Motivated by the above challenges, this work introduces TelePhysicalOperation, a novel teloperation concept, which relies on a virtual physical interaction interface between the human operator and the remote robot in a manner that is equivalent to a “Marionette” based interaction interface. With the proposed approach, the user can virtually “interact” with the remote robot, through the application of virtual forces, which are generated by the operator tracking system and can be then selectively applied to any body part of the remote robot along its kinematic chain. This leads to the remote robot generating motions that comply with the applied virtual forces, thanks to the underlying control architecture. The proposed method permits to command the robot from a distance by exploring the intuitiveness of the “Marionette” based physical interaction with the robot in a virtual/remote manner. The details of the proposed approach are introduced and its effectiveness is demonstrated through a number of experimental trials executed on the CENTAURO, a hybrid leg-wheel platform with an anthropomorphic upper body.

The impact of different AR-HUD virtual warning interfaces on the takeover performance and visual characteristics of autonomous vehicles

Objective The objective of this study was to determine the different effects of the arrow-pointing augmented reality head-up display (AR-HUD) interface, virtual shadow AR-HUD interface, and non-AR-HUD interface on autonomous vehicle takeover efficiency and driver eye movement characteristics in different driving scenarios. Methods Thirty-six participants were selected to carry out a simulated driving experiment, and the eye movement index and takeover time were analyzed. Results The arrow pointing AR-HUD interface and the virtual shadow AR-HUD interface could effectively reduce the driver's visual distraction, improve the efficiency of obtaining visual information, reduce the number of times the driver's eyes leave the road, and improve the efficiency of the takeover compared with the non-AR-HUD interface, but there was no significant difference in eye movement indexes between the arrow pointing AR-HUD interface and the more eye-catching virtual shadow AR-HUD interface. When specific scenarios were considered, it was found that in the scenario of emergency braking of the vehicle in front, the arrow pointing AR-HUD interface and the virtual shadow AR-HUD interface had more advantages in takeover efficiency than the non-AR-HUD interface. However, in the scenarios of a rear vehicle overtaking the vehicle ahead and non-motor vehicles running red lights, there was no significant difference in takeover efficiency. For the non-motor vehicle invading the line, emergency U-turn of the vehicle in front, and pedestrian crossing scenarios, the virtual shadow AR-HUD interface had the highest takeover efficiency. Conclusions These research results can help improve the active safety of autonomous vehicle AR-HUD interfaces.

PARS, low-cost portable rehabilitation system for upper arm

This study introduces a compact low-cost single degree of freedom end-effector type upper arm rehabilitation system (PARS) along with its hardware and software elements. Proposed system is also suitable to be used in conjunction with a gaming environment. Throughout the study structural setup of the system was explained in detail along with its electronics, control system and gaming software. Introduced virtual gaming interface supports various game levels with different difficulties generated via interaction type control algorithms. Having simple structural design constructed by using basic available components, proposed system can be easily manufactured and utilized in physical rehabilitation procedures by using supplied open source codes. Introduced systems compactness and user friendly interface also allow its usage for individual home therapies for remote rehabilitation treatment procedures.

A lower limb rehabilitation platform with mirror therapy, electrical stimulation and virtual reality for people with limited dorsiflexion movement

This paper presents a low-cost portable system for applying a rehabilitation therapy, based on virtual reality, functional electrical stimulation and a training device. This open-hardware system, intended to support a home-made therapy process in people with reduced dorsiflexion ability, contains three main building blocks: an electromechanical platform, an immersive virtual reality interface and the firmware. The electromechanical training platform is the core of the system, which acts as a gateway interface of sensors-actuators for a closed loop system, through an immersive virtual reality application, the patient closes the loop by acting as the controller by means of a “virtual dummy” preforming in mirror configuration.The platform measures and process the dorsiflexion angle described by both ankles, real-time transmitting the information to the mobile phone virtual application to be presented as a mirror. The onboard microprocessor drives the operation of the electric stimulation interface, which is sent through two channels to both, healthy and affected lower limbs. The platform communicates continuously through a USB bidirectional interface with a personal computer, in which the physician enters the rehabilitation protocol and follows the patient performance. A first case study by using this device has been reported in [1].

Scale development for analyzing the fit of real and virtual world integration: an example of Pokémon Go

PurposeAugmented reality (AR) has become a trend, and the effects of Pokémon Go, the most popular online and mobile game, have been explored in many studies. However, few studies have developed questionnaires of fit to investigate the relationship between the fit and the integration of the game's virtual world and reality. The paper intends to integrate the models of stimulus-organism-response (S-O-R) and information systems success with cognitive fit theory to explore the fit and reactions of users in the integration of real and virtual worlds.Design/methodology/approachFollowing MacKenzie's scale development, two surveys were conducted. The first survey was conducted to perform a scale development of fit. The second survey was collected from 315 Pokémon Go players to validate the fit scale and it was analyzed via structural equation modeling.FindingsThe results show that scale development of fit has good reliability and validity. Furthermore, game information quality, game system quality and virtual (Pokémon) characteristics have significantly positive effects on cognitive and emotional fit. Cognitive and emotional fit have significant positive effects on user satisfaction, and user satisfaction has significant positive effects on continued intention to play. The results suggest that maintaining the quality of the game and improving the virtual interface will provide a better fit between the real and virtual worlds, enhancing user satisfaction with the fit as well as their intention for continued use.Originality/valueAlthough fit has been widely studied in various contexts, the application of AR has been rarely discussed. This study develops a scale of fit and takes Pokémon Go as the subject to validate the fit measurement and discuss players' cognition and feelings regarding the game. The authors measure user reactions to different stimuli and explore cognitive and emotional fit as well as the integration of virtual worlds and reality. In sum, to the best of the authors’ knowledge, this is one of the earliest studies to explore and develop a cognitive and emotional fit scale for future researchers and practitioners.

Virtual Reality Systems as an Orientation Aid for People Who Are Blind to Acquire New Spatial Information.

This research aims to examine the impact of virtual environments interface on the exploration process, construction of cognitive maps, and performance of orientation tasks in real spaces by users who are blind. The study compared interaction with identical spaces using different systems: BlindAid, Virtual Cane, and real space. These two virtual systems include user-interface action commands that convey unique abilities and activities to users who are blind and that operate only in these VR systems and not in real space (e.g., teleporting the user’s avatar or pointing at a virtual object to receive information). This research included 15 participants who are blind, divided into three groups: a control group and two experimental groups. Varied tasks (exploration and orientation) were used in two virtual environments and in real spaces, with both qualitative and quantitative methodologies. The results show that the participants were able to explore, construct a cognitive map, and perform orientation tasks. Participants in both virtual systems used these action commands during their exploration process: all participants used the teleport action command to move their avatar to the starting point and all Virtual Cane participants explored the environment mainly by using the look-around mode, which enabled them to collect spatial information in a way that influenced their ability to construct a cognitive map based on a map model.

Features of the organization and classification of virtual reality interfaces

The subject of the study is the features of the organization of virtual reality interfaces. The author examines in detail such aspects of the topic as user involvement in the virtual environment, various ways and scenarios of user interaction with virtual reality, user security in the virtual environment, as well as such a phenomenon as cyberbullying and ways to prevent it. The study also considers the use of voice control as an alternative to manual. Particular attention in this study is paid to the classification of virtual reality interfaces, among which sensory interfaces, interfaces based on user motor skills, sensorimotor interfaces, interfaces for modeling and developing virtual reality are distinguished and considered in detail. The main conclusion of the study is that the virtual reality interface should be designed taking into account the ergonomics of users to prevent muscle fatigue and cyber-pain. In addition, it is very important to ensure the user's safety when designing virtual environment interfaces: using the virtual reality interface should not lead to injury to the user. To create an ergonomic and secure virtual reality interface, a combination of different types of interfaces is often required, through which the user can access an alternative control method or improved navigation. A special contribution of the author to the study of the topic is the description of the classification of virtual reality interfaces.

Analytical approach to the solution of short-crested wave interaction with V-shaped and arc-shaped breakwaters

The hydrodynamic performance of short-crested wave diffraction by bottom-mounted V-shaped and arc-shaped breakwaters was examined based on the linear wave theory and the eigenfunction expansion method, respectively. Both types of breakwaters are assumed to be thin, impermeable, vertical, and rigidly embedded in the seabed. With the help of a virtual interface, the fluid domains were subdivided into subdomains and the velocity potential in each subdomain was described by eigenfunctions. The linear algebraic equations that determine the unknown coefficients can be obtained using the boundary and matching conditions. The analytical models fully agree with previous predictions. The major factors including wave propagation direction, opening angle, and water depth that affect wave forces and run-ups were explored. The results showed that the wave patterns of short-crested waves near breakwaters were quite different from those of long-crested waves, and using the long-crested wave model can overestimate the wave-defending effects of the breakwaters in a short-crested sea. An analogous wave attenuation effect was observed for breakwaters with comparable structures, which means that engineering practice has a certain degree of substitutability between them.

Gesture objects detection and tracking for virtual text entry keyboard interface

Gesture objects detection and tracking for virtual text entry keyboard interface

The role of spatial ability in mixed reality learning with the HoloLens.

The use of mixed reality in science education has been increasing and as such it has become more important to understand how information is learned in these virtual environments. Spatial ability is important in many learning contexts, but especially in neuroanatomy education where learning the locations and spatial relationships between brain regions is paramount. It is currently unclear what role spatial ability plays in mixed reality learning environments, and whether it is different compared to traditional physical environments. To test this, a learning experiment was conducted where students learned neuroanatomy using both mixed reality and a physical plastic model of a brain (N = 27). Spatial ability was assessed and analyzed to determine its effect on performance across the two learning modalities. The results showed that spatial ability facilitated learning in mixed reality (β = 0.21, P = 0.003), but not when using a plastic model (β = 0.08, P = 0.318). A non-significant difference was observed between the modalities in terms of knowledge test performance (d = 0.39, P = 0.052); however, mixed reality was more engaging (d = 0.59, P = 0.005) and learners were more confident in the information they learned compared to using a physical model (d = 0.56, P = 0.007). Overall, these findings suggest that spatial ability is more relevant in virtual learning environments, where the ability to manipulate and interact with an object is diminished or abstracted through a virtual user interface.

Evaluating Virtual Patient Interaction Fidelity With Advanced Communication Skills Learners

Previous research in educational medical simulation has drawn attention to the interplay between a simulation’s fidelity and its educational effectiveness. As virtual patients (VPs) are increasingly used in medical simulations for education purposes, a focus on the relationship between virtual patients’ fidelity and educational effectiveness should also be investigated. In this paper, we contribute to this investigation by evaluating the use of a virtual patient selection interface (in which learners interact with a virtual patient via a set of pre-defined choices) with advanced medical communication skills learners. To this end, we integrated virtual patient interviews into a graduate-level course for speech-language therapists over the course of 2 years. In the first cohort, students interacted with three VPs using only a chat interface. In the second cohort, students used both a chat interface and a selection interface to interact with the VPs. Our results suggest that these advanced learners view the selection interfaces as more appropriate for novice learners and that their communication behavior was not significantly affected by using the selection interface. Based on these results, we suggest that selection interfaces may be more appropriate for novice communication skills learners, but for applications in which selection interfaces are to be used with advanced learners, additional design research may be needed to best target these interfaces to advanced learners.

The Utility of Telemedicine to Manage Post-Operative Pain

Telemedicine is defined as practicing medicine via a virtual interface, including email, telephone calls, text messages, video chatting, and personalized online programs. Telemedicine has increased over the past few decades, mainly in psychology and primary care. Recently, surgical specialties have also begun to utilize telemedicine for post-operative care. There are many studies examining telemedicine’s use in managing post-operative pain. This review paper focuses on 17 on postoperative pain management. They found that telemedicine can assist physicians in managing post-operative pain remotely by increasing adherence to post-operative regimens (p < 0.001), providing greater individualized care (p = 0.01), and decreasing post-operative pain medication dependence (p = 0.04).