Video Conference System in Mixed Reality Using a Hololens

The mixed reality conference system proposed in this paper is a robust,real-time video conference application software that makes up for the simple interaction and lack of immersion and realism of traditional video conference,which realizes the entire process of holographic video conference from client to cloud to the client.This paper mainly focuses on designing and implementing a video conference system based on AI segmentation technology and mixed reality.Several mixed reality conference system components are discussed,including data collection,data transmission,processing,and mixed reality presentation.The data layer is mainly used for data collection,integration,and video and audio codecs.The network layer uses Web-RTC to realize peer-to-peer data communication.The data processing layer is the core part of the system,mainly for human video matting and human-computer interaction,which is the key to realizing mixed reality conferences and improving the interactive experience.The presentation layer explicitly includes the login interface of the mixed reality conference system,the presentation of real-time matting of human subjects,and the presentation objects.With the mixed reality conference system,conference participants in different places can see each other in real-time in their mixed reality scene and share presentation content and 3D models based on mixed reality technology to have a more interactive and immersive experience.

解剖性后腹腔镜切除术治疗肾上腺肿瘤患者56例临床疗效观察

目的:探讨解剖性后腹腔镜切除术在肾上腺肿瘤患者治疗中的应用效果。方法:选取2016年1月至2021年1月解放军总医院第三医学中心泌尿外科收治的肾上腺肿瘤患者112例作为研究对象,按照双盲法将患者随机分为对照组和研究组,每组56例。对照组患者采用经腹入路腹腔镜治疗,研究组患者则采用解剖性后腹腔镜治疗,比较2种手术方式术后临床指标的变化;采用酶联免疫吸附实验检测患者术前和术后6 h血清白细胞介素-6(IL-6)、白细胞介素-1β(IL-1β)、超敏C反应蛋白(hs-CRP)等炎性因子水平;采用美国Medica电解质分析仪检测患者血清Na+和K+及HCO^(-)_(3)水平;同时观察患者预后及并发症发生情况。结果:研究组手术时间、引流管放置时间、胃肠功能恢复时间和住院时间均短于对照组,差异有统计学意义(P<0.05或P<0.01)。研究组术后血清IL-6、IL-1β、hs-CRP水平明显低于对照组,Na+、HCO^(-)_(3)水平低于对照组,K+水平则高于对照组,差异均有统计学意义(P<0.05或P<0.01)。研究组术后并发症发生率[14.29%(8/56)]明显低于对照组[14.29%(8/56)],差异有统计学意义(χ^(2)=3.953,P=0.047)。术后随访6个月2组患者均未出现复发或转移。结论:解剖性后腹腔镜切除术治疗肾上腺肿瘤能够更好地减轻手术对患者造成的创伤,减少对患者内环境的影响,有效促进其术后康复进程,且具有更高的安全性。

Heat transfer and fluid flow and their effects on the solidification microstructure in full-penetration laser welding of aluminum sheet

Understanding the behaviors of heat transfer and fluid flow in weld pool and their effects on the solidification microstructure are significant for performance improvement of laser welds.This paper develops a three-dimensional numerical model to understand the multi-physical processes such as heat transfer,melt convection and solidification behavior in full-penetration laser welding of thin 5083 aluminum sheet.Solidification parameters including temperature gradient G and solidification rate R,and their combined forms are evaluated to interpret solidification microstructure.The predicted weld dimensions and the microstructure morphology and scale agree well with experiments.Results indicate that heat conduction is the dominant mechanism of heat transfer in weld pool,and melt convection plays a critical role in microstructure scale.The mushy zone shape/size and solidification parameters can be modulated by changing process parameters.Dendritic structures form because of the low G/R value.The scale of dendritic structures can be reduced by increasing GR via decreasing heat input.The columnar to equiaxed transition is predicted quantitatively via the process related G^3/R.These findings illustrate how heat transfer and fluid flow affect the solidification parameters and hence the microstructure,and show how to improve microstructure by optimizing the process.

The Teaching and Learning of Chinese as a Second or Foreign Language:The Current Situation and Future Directions

In this opening commentary,we highlight the development of the teaching and learning of Chinese as a second or foreign language(CSL/CFL),which has attracted much attention from researchers,language educators,and other stakeholders worldwide.To contribute to this ongoing examination and discussion,this special issue documents the collective efforts of scholars in different educational contexts to review six critical issues in teaching and learning CSL/CFL:learning and instruction of reading Chinese as an additional language,Chinese character teaching and learning,learner identity in CSL/CFL education,teaching and learning Chinese through immersion,technology assisted CSL/CFL teaching and learning,and mobile assisted learning CFL.We contend that all efforts to address these critical issues require constant examination to facilitate further development in CSL/CFL education around the world.

Language Learning Strategies Used by Asian Students in English-medium Universities

An increasing number of Asian students pursue English medium tertiary education for better academic credentials.These students face daunting linguistic challenges in their struggle for academic survival and success.This article gives an overview of language learning strategy(LLS)research undertaken in two theoretical and methodological orientations,namely,psychometric survey studies using a strategy inventory and sociocultural,largely qualitative research that examines learners'strategy use in relation to contextual mediation.Under each category of research,the article reviews four studies on Asian students'strategy use in different research contexts including Britain,Canada,Hong Kong,India,New Zealand and United States.It also documents relevant critiques associated with these studies.Given the widely accepted importance of strategy use in language learning,it can be argued that research on Asian tertiary students'strategy use in English medium universities informs an institutional effort to support their pursuit of linguistic competence.