Influence of multi-modality on moving target selection in virtual reality

Background Owing to recent advances in virtual reality(VR)technologies,effective user interaction with dynamic content in 3D scenes has become a research hotspot.Moving target selection is a basic interactive task in which the user performance research in tasks is significant to user interface design in VR.Different from the existing static target selection studies,the moving target selection in VR is affected by the change in target speed,angle and size,and lack of research on some key factors.Methods This study designs an experimental scenario in which the users play badminton under the condition of VR.By adding seven kinds of modal clues such as vision,audio,haptics,and their combinations,five kinds of moving speed and four kinds of serving angles,and the effect of these factors on the performance and subjective feelings in moving target selection in VR,is studied.Results The results show that the moving speed of the shuttlecock has a significant impact on the user performance.The angle of service has a significant impact on hitting rate,but has no significant impact on the hitting distance.The acquisition of the user performance by the moving target is mainly influenced by vision under the combined modalities;adding additional modalities can improve user performance.Although the hitting distance of the target is increased in the trimodal condition,the hitting rate decreases.Conclusion This study analyses the results of user performance and subjective perception,and then provides suggestions on the combination of modality clues in different scenarios.

Analysis of the Properties and Anti-Seepage Mechanism of PBFC Slurry in Landfill

As the landfill leachate has strong pollution on the underground water,surface water and soil.This paper develops the formula of impervious slurry with low permeability,good durability,strong adsorption and retardant based on the bentonite which is modified by polyvinyl alcohol.Through the simulation experiment,the optimum formula of polyvinyl alcohol is 0.2%.Its osmotic coefficient for 28 days is 0.53×10^-8~1.86×10^-8 cm/s and compressive strength is 0.5~1.5 MPa as well.This paper study on the retardant rule of the consolidation of slurry against the pollution in the leachate by self-made percolation instrument.The experiment shows that the retardant rate of the consolidation against inorganic pollutants and organic pollutants is over 85% and the retardant rate against heavy metal ion such as Hg and Pb is above 99%.The slurry has the characteristics of low permeability,high retardant against pollution,good durability and plasticity,no chemical additives,no pollution,wide source of raw materials and good economy which determine it can be used to new landfill or existing landfill,building foundation pit and water conservancy project.

Trajectory prediction model for crossing-based target selection

Background Crossing-based target selection motion may attain less error rates and higher interactive speed in some cases.Most of the research in target selection fields are focused on the analysis of the interaction results.Additionally,as trajectories play a much more important role in crossing-based target selection compared to the other interactive techniques,an ideal model for trajectories can help computer designers make predictions about interaction results during the process of target selection rather than at the end of the whole process.Methods In this paper,a trajectory prediction model for crossing based target selection tasks is proposed by taking the reference of a dynamic model theory.Results Simulation results demonstrate that our model performed well with regard to the prediction of trajectories,endpoints and hitting time for target-selection motion,and the average error of trajectories,endpoints and hitting time values were found to be 17.28%,2.73mm and 11.50%,respectively.