Eye gaze can be a potentially fast and ergonomic method for target selection in augmented reality (AR). However, the eye-tracking accuracy of current consumer-level AR systems is limited. While ...state-of-the-art AR target selection techniques based on eye gaze and touch (gaze-touch), which follow the "eye gaze pre-selects, touch refines and confirms" mechanism, can significantly enhance selection accuracy, their selection speeds are usually compromised. To balance accuracy and speed in gaze-touch grid menu selection in AR, we propose the Hand-Held Sub-Menu (HHSM) technique.tou HHSM divides a grid menu into several sub-menus and maps the sub-menu pointed to by eye gaze onto the touchscreen of a hand-held device. To select a target item, the user first selects the sub-menu containing it via eye gaze and then confirms the selection on the touchscreen via a single touch action. We derived the HHSM technique's design space and investigated it through a series of empirical studies. Through an empirical study involving 24 participants recruited from a local university, we found that HHSM can effectively balance accuracy and speed in gaze-touch grid menu selection in AR. The error rate was approximately 2%, and the completion time per selection was around 0.93 s when participants used two thumbs to interact with the touchscreen, and approximately 1.1 s when they used only one finger.
While numerous studies have explored using various sensing techniques to measure attention states, moment-to-moment attention fluctuation measurement is unavailable. To bridge this gap, we applied a ...novel paradigm in psychology, the gradual-onset continuous performance task (gradCPT), to collect the ground truth of attention states. GradCPT allows for the precise labeling of attention fluctuation on an 800 ms time scale. We then developed a new technique for measuring continuous attention fluctuation, based on a machine learning approach that uses the spectral properties of EEG signals as the main features. We demonstrated that, even using a consumer grade EEG device, the detection accuracy of moment-to-moment attention fluctuations was 73.49%. Next, we empirically validated our technique in a video learning scenario and found that our technique match with the classification obtained through thought probes, with an average F1 score of 0.77. Our results suggest the effectiveness of using gradCPT as a ground truth labeling method and the feasibility of using consumer-grade EEG devices for continuous attention fluctuation detection.
The design of colormaps can help tomography operators obtain accurate visual comprehension, thereby assisting safety-critical decisions. The research presented here is about deploying colormaps that ...promote the best affective responses for industrial microwave tomography (MWT). To answer the two research questions related to our study, we firstly conducted a quantitative analysis of 11 frequently-used colormaps on a segmentation task. Secondly, we presented the same colormaps within a crowdsourced study comprising two parts to verify the quantitative outcomes. The first part encoded affective responses from participants into a prevailing four-quadrant valence–arousal grid; the second part recorded participant ratings towards the accuracy of each colormap on MWT segmentation. We concluded that three colormaps are the best suited in the context of MWT tasks. We also found that the colormaps triggering emotions in the positive–exciting quadrant can facilitate more accurate visual comprehension than other affect-related quadrants. A synthetic colormap design guideline was consequently proposed.
This paper mainly studies the vibration isolation of negative Poisson’s ratio structure in the honeycomb base of ships. Based on the structure of the negative Poisson’s ratio structure, different ...laying methods and different cell structure are used to construct the honeycomb base with the re-entrant hexagonal cell, the mathematical expression of Poisson’s ratio of a single re-entrant hexagonal cell structure is obtained through theoretical analysis. The negative Poisson ratio and relative density could be got by changing the angle and side thickness of the cell structure. Based on the different energy band of the re-entrant hexagonal cell structure, the different negative Poisson’s ratio re-entrant hexagonal honeycomb base was got, the energy band and the frequency response curve of the ship base are analyzed by COMSOL software. The energy band diagram and the frequency response of the structure are obtained to analyze the vibration isolation performance of the honeycomb base. By comparing the experimental results, the following conclusions can be gotten: (1) Compared with the traditional base, the negative Poisson’s ratio base has better vibration isolation effect on external excitation; (2) Different laying method and Poisson ratios can get different isolation effect. The combined base structure can provide better isolation effect to the external excitation in a larger frequency band; (3) By adding different mass blocks to the inner or peripheral angles of the basic re-entrant hexagonal cell, the vibration isolation performance of the structure can be changed to better.
This paper is concerned with the application of the localized Fourier collocation method (LFCM), a newly-developed meshless collocation method, for the numerical solution of high-order partial ...differential equations (PDEs). In the present method, the entire computational domain is divided into a set of overlapping subdomains in which the Fourier series expansion and moving-least square approximation are applied to construct the local systems of linear equations. By satisfying the governing equations and the corresponding boundary conditions, a sparse and banded stiffness matrix can be established which makes the method very attractive for large-scale engineering simulations. Preliminary numerical experiments for fourth-order PDEs in both two- and three-dimensions are presented to demonstrate the accuracy and efficiency of the present method.
Efficient acoustic communication across the water-air interface remains a great challenge owing to the extreme acoustic impedance mismatch. Few present acoustic metamaterials can be constructed on ...the free air-water interface for enhancing the acoustic transmission because of the interface instability. Previous strategies overcoming this difficulty were limited in practical usage, as well as the wide-angle and multifrequency acoustic transmission. Here, we report a simple and practical way to obtain the wide-angle and multifrequency water-air acoustic transmission with a tunable fluid-type acoustic metasurface (FAM). The FAM has a transmission enhancement of acoustic energy over 200 times, with a thickness less than the wavelength in water by three orders of magnitude. The FAM can work at an almost arbitrary water-to-air incident angle, and the operating frequencies can be flexibly adjusted. Multifrequency transmissions can be obtained with multilayer FAMs. In experiments, the FAM is demonstrated to be stable enough for practical applications and has the transmission enhancement of over 20 dB for wide frequencies. The transmission enhancement of music signal across the water-air interface was performed to demonstrate the applications in acoustic communications. The FAM will benefit various applications in hydroacoustics and oceanography.
To examine the effectiveness of a web-based clinical pedagogy program on nurse preceptors’ clinical teaching competency, self-efficacy, and attitudes toward web-based learning in comparison to ...face-to-face course.
Preceptorship is a dynamic educational process that requires designing, and implementing various teaching strategies, evaluation, assessment and feedback. Web-based learning has been recognized as an effective learning approach for nursing professional development.
A prospective quasi-experimental approach with two-group pre-test and post-test repeated measures was adopted.
The web-based clinical pedagogy program was provided to the preceptors in the experimental group, while control group received the face-to-face preceptorship course. Clinical Teaching Competence Inventory (CTCI), Preceptor Self-efficacy Assessment Instrument (PSEQ), and Attitudes toward Web-based Continuing Learning Survey (AWCLS) were used to evaluate preceptors’ learning outcomes. Data were collected at three time points – before, immediately after the learning program, and after 6 months of the clinical teaching experience.
A total of 150 nurses (75 participants/group) were recruited from a tertiary hospital in Singapore from July 2018 to June 2020. The results from the repeated measures analysis of covariance showed that there was a significant interaction effect (group x time) on the overall CTCI score after adjusting for covariate (F = 5.390, p = 0.005). However, there were no significant interaction effect (group x time) on PSEQ (F = 2.693, p = 0.070) and overall AWCLS score (F = 1.341, p = 0.264) between the two groups across the three time points.
The web-based clinical pedagogy program produced outcomes comparable to the face-to-face program in terms of preceptors’ clinical teaching competence and self-efficacy. The innovative and cost-effective web-based clinical pedagogy program provided professional development and the flexibility to accommodate preceptors’ busy work schedules. Online learning has become increasingly popular during the COVID-19 pandemic and the web-based clinical pedagogy program was implemented when face-to-face workshop was not feasible.
LSVP Ram, Ashwin; Zhao, Shengdong
Proceedings of ACM on interactive, mobile, wearable and ubiquitous technologies,
03/2021, Letnik:
5, Številka:
1
Journal Article
Recenzirano
The ubiquity of mobile phones allows video content to be watched on the go. However, users' current on-the-go video learning experience on phones is encumbered by issues of toggling and managing ...attention between the video and surroundings, as informed by our initial qualitative study. To alleviate this, we explore how combining the emergent smart glasses (Optical Head-Mounted Display or OHMD) platform with a redesigned video presentation style can better distribute users' attention between learning and walking tasks. We evaluated three presentation techniques: highlighting, sequentiality, and data persistence to find that combining sequentiality and data persistence is highly effective, yielding a 56% higher immediate recall score compared to a static video presentation. We also compared the OHMD against smartphones to delineate the advantages of either platform for on-the-go video learning in the context of everyday mobility tasks. We found that OHMDs improved users' 7-day delayed recall scores by 17% while still allowing 5.6% faster walking speed, especially during complex mobility tasks. Based on the findings, we introduce Layered Serial Visual Presentation (LSVP) style, which incorporates sequentiality, strict data persistence, and transparent background, among other properties, for future OHMD-based on-the-go video learning.
In this paper, a meshless collocation method is introduced for two-dimensional (2D) and three-dimensional (3D) transient elastodynamic problems by applying the generalized finite difference method ...(GFDM) in conjunction with the Houbolt scheme. Coupled equilibrium equations with a time-dependent loading are transformed into the static equations at time nodes by adopting the Houbolt method. After then, the solution of the static equations is achieved with the GFDM with second-order and fourth-order expansions. Several numerical examples involving complicated geometries and different initial and boundary conditions are simulated to validate the performance of the present approach.
Ray-casting is a fundamental 3D target acquisition technique in virtual environments. With ray-casting, users emit a ray to highlight a desired target before pressing a button to select it; however, ...due to hand tremor, tracker jitter, and the Heisenberg effect, the ray direction can be shifted during the button pressing process, causing wrong selections. To improve selection accuracy, instead of selecting an object at a button press, we backtrack the interaction history to the time when the desired target is highlighted and select that instead. Inspired by Kopper et al.’s predictive model of distal pointing, we hypothesized that the optimal backtrack time depends on the object’s angular size. We validated our hypothesis through an experiment and implemented BackTracer based on the results. Moreover, BackTracer was evaluated against basic ray-casting, state-of-the-art history-based ray-casting, and state-of-the-art progressive refinement ray-casting, and results indicated that BackTracer significantly improved the accuracy and selection efficiency, making it a promising technique for 3D target acquisition.
•We proposed BackTracer-a 3D target acquisition technique.•BackTracer selects the object under the ray mostly in its backtracking time interval.•The optimal backtracking time interval depends on angular object sizes.•BackTracer outperforms the baselines when the target is small and highly occluded.•BackTracer can be integrated into Fitts’ law-based method and improve accuracy.
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