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3篇 您的检索式:作者名="Ximeng Cheng"
    题名 作者 年代 出处 被引量
1Enhanced secondary pollution offset reduction of primary emissions during COVID-19 lockdown in China显示文摘To control the spread of the 2019 novel coronavirus(COVID-19),China imposed nationwide restrictions on the movement of its population(lockdown)after the Chinese New Year of 2020,leading to large reductions in economic activities and associated emissions.Despite such large decreases in primary pollution,there were nonetheless several periods of heavy haze pollution in eastern China,raising questions about the well-established relationship between human activities and air quality.Here,using comprehensive measurements and modeling,we show that the haze during the COVID lockdown was driven by enhancements of secondary pollution.In particular,large decreases in NOx emissions from transportation increased ozone and nighttime NO_(3)radical formation,and these increases in atmospheric oxidizing capacity in turn facilitated the formation of secondary particulate matter.Our results,afforded by the tragic natural experiment of the COVID-19 pandemic,indicate that haze mitigation depends upon a coordinated and balanced strategy for controlling multiple pollutants.Xin Huang Aijun Ding Jian Gao Bo Zheng Derong Zhou Ximeng Qi Rong Tang Jiaping Wang Chuanhua Ren Wei Nie Xuguang Chi Zheng Xu Liangduo Chen Yuanyuan Li Fei Che Nini Pang Haikun Wang Dan Tong Wei Qin Wei Cheng Weijing Liu Qingyan Fu Baoxian Liu Fahe Chai Steven JDavis Qiang Zhang Kebin He 2021National Science Review2021,8,2:47
2Design and manufacture AR head-mounted displays:A review and outlook显示文摘Augmented reality head-mounted displays(AR-HMDs)enable users to see real images of the outside world and visualize virtual information generated by a computer at any time and from any location,making them useful for various applications.The manufacture of AR-HMDs combines the fields of optical engineering,optical materials,optical coating,precision manufacturing,electronic science,computer science,physiology,ergonomics,etc.This paper primarily focuses on the optical engineering of AR-HMDs.Optical combiners and display devices are used to combine real-world and virtual-world objects that are visible to the human eye.In this review,existing AR-HMD optical solutions employed for optical combiners are divided into three categories:optical solutions based on macro-,micro-,and nanooptics.The physical principles,optical structure,performance parameters,and manufacturing process of different types of AR-HMD optical solutions are subsequently analyzed.Moreover,their advantages and disadvantages are investigated and evaluated.In addition,the bottlenecks and future development trends in the case of AR-HMD optical solutions are discussed.Dewen Cheng Qiwei Wang Yue Liu Hailong Chen Dongwei Ni Ximeng Wang Cheng Yao Qichao Hou Weihong Hou Gang Luo Yongtian Wang 2021Light(Advanced Manufacturing)2021,2,3:6
3A framework for mixed-use decomposition based on temporal activity signatures extracted from big geo-data显示文摘Mixed use has been extensively applied as an urban planning principle and hinders the study of single urban functions.To address this problem,it is worth decomposing the mixed use.Inspired by the concept of spectral unmixing in remote sensing applications,this paper proposes a framework for mixed-use decomposition based on big geo-data.Mixeduse decomposition in terms of human activities differs from traditional land use research,and it is more reasonable to infer the actual urban function of land.The framework consists of four steps,namely temporal activity signature extraction,urban function base curve extraction,mixeduse decomposition,and result validation.First,the temporal activity signatures(TASs)of each zone are extracted as the proxy of human activity patterns.Second,the diurnal TASs of routine activities are extracted as urban function base curves(i.e.endmembers).Third,a linear decomposition model is used to decompose the mixed use and obtain multiple results(urban function composition,dynamic activity proportions,and the mixing index).Finally,result validation strategies are concluded.This framework offers method extensibility and has few requirements for the input data.It is validated by means of a case study of Beijing,based on a social media check-in dataset.Lun Wu Ximeng Cheng Chaogui Kang Di Zhu Zhou Huang Yu Liu 2020International Journal of Digital Earth2020,13,6:2
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