Browsing by Author "Xu, Yan"

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    Exploring Spatial UI Transition Mechanisms with Head-Worn Augmented Reality
    Lu, Feiyu; Xu, Yan (ACM, 2022-04-29)
    Imagine in the future people comfortably wear augmented reality (AR) displays all day, how do we design interfaces that adapt to the contextual changes as people move around? In current operating systems, the majority of AR content defaults to staying at a fxed location until being manually moved by the users. However, this approach puts the burden of user interface (UI) transition solely on users. In this paper, we frst ran a bodystorming design workshop to capture the limitations of existing manual UI transition approaches in spatially diverse tasks. Then we addressed these limitations by designing and evaluating three UI transition mechanisms with different levels of automation and controllability (low-efort manual, semi-automated, fully-automated). Furthermore, we simulated imperfect contextual awareness by introducing prediction errors with diferent costs to correct them. Our results provide valuable lessons about the trade-ofs between UI automation levels, controllability, user agency, and the impact of prediction errors.
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    Numerical Investigation of Cavitating Jet Flow Field with Different Turbulence Models
    Li, Lidong; Xu, Yan; Ge, Mingming; Wang, Zunce; Li, Sen; Zhang, Jinglong (MDPI, 2023-09-19)
    In numerous industries such as drilling, peening, cleaning, etc., a cavitating jet is adopted. However, it is challenging to simulate the cavitating flow field numerically with accuracy. The flow field of the organ pipe cavitation nozzle is simulated in this research using the RNG k−ε, DES, and LES turbulence models. The LES model can more accurately predict the periodic shedding of a cavitating cloud, which is basically consistent with the jet morphology captured with a high−speed camera. The flow pattern, cavitating cloud evolution and shedding period of a cavitating jet are analyzed. The findings demonstrate that the LES model produces a cavitating effect inside the nozzle that is superior to those produced by the RNG k−ε and DES models. The vortex rings in the diffusion section are simulated using the LES model, which accelerates cavitation. The cavitating clouds of the organ pipe nozzle show periodic evolutions, with stages of generation, development, shedding and collapse. The periodic shedding of the cavitating clouds exhibits a similar pattern in the vorticities simulated using the LES model, and the vorticities display the small-scale structures where the cavitating bubbles collapse. This study can provide a reference for the simulation of a cavitating jet and the analysis of the cavitating mechanism.