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Hydro-climatic Characteristics of Yarlung Zangbo River Basin since the Last Glacial Maximum

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Advances in Atmospheric Sciences 2022年第3期39卷 415-426页

作者： Shuang liu Kaiheng HU weiming liu Paul A.CARLING Institute of Mountain Hazards and Environment Chinese Academy of SciencesChengdu 610041China Geography&Environment University of SouthamptonHighfieldSouthamptonSO171BJUK

Global climate changes significantly impact the water condition of big rivers in glacierized high mountains. However,there is a lack of studies on hydrological changes within river basins caused by climate changes over a geological timescale due to the impossibility of direct observations. In this study, we examine the hydro-climatic variation of the Yarlung Zangbo River Basin in the Tibet Plateau since the Last Glacial Maximum(LGM) by combining δ18 O proxy records in Indian and Omani caves with the simulated Indian summer monsoon, surface temperature, precipitation, evapotranspiration and runoff via the Community Climate System Model and the reconstructed glacier coverage via the Parallel Ice Sheet Model. The mean river runoff was kept at a low level of 145 billion cubic meters per year until an abrupt increase at a rate of 8.7 million cubic meters per year in the B?lling-Aller?d interval(BA). The annual runoff reached a maximum of 250 billion cubic meters in the early Holocene and then reduced to the current value of 180 billion cubic meters at a rate of 6.4 million cubic meters per year. The low runoff in the LGM and Heinrich Stadial 1(HS1) is likely attributed to such a small contribution of precipitation to runoff and the large glacier cover. The percentage of precipitation to runoff was only 20%during the LGM and HS1. Comparison of glacier area among different periods indicates that the fastest deglaciation occurred during the late HS1, when nearly 60% of glacier area disappeared in the middle reach, 50% in the upper reach,and 30% in the lower reach. The rapid deglaciation and increasing runoff between the late HS1 and BA may have accelerated widespread ice-dam breaches and led to extreme outburst flood events. Combining local geological proxy records and regional simulations could be a useful approach for the study of paleo-hydrologic variations in big river basins.

关键词： Yarlung Zangbo River Basin Indian summer monsoon glacier change runoff variability since the LGM

Dual-functional conductive nanofilm absorber

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Nano Research 2023年第12期16卷 13375-13380页

作者： Hongyan liu Zheng Xie weiming liu Hongdong Li Yue Yan Xiaoli Wang Beijing Institute of Aeronautical Materials Beijing 100095China College of Rare Earth and Faculty of Materials Metallurgy and Chemistry Jiangxi University of Science and TechnologyGanzhou 341000China CAS Key Laboratory of Nanosystem and Hierarchical Fabrication National Center for Nanoscience and TechnologyBeijing 100190China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of SciencesBeijing 100049China

Converting solar energy by to other forms of energy has attracted a lot of interest from academy to industry.However,the overall utilization efficiency of solar energy is inferior due to the limited effective solar spectrum range.Here,in order to utilize the broadband solar spectrum more efficiently,a novel hybrid absorber structure was proposed,which consists of a four-layer planar nanofilm with dual functions of heat absorption and photocatalysis.The average absorption in the visible range is larger than 0.95,and in the near-infrared spectral region,the average absorption is still larger than 0.85.The overall absorption of the absorber is over 0.86,while the thermal emittance is lower than 0.04,which can lead to remarkable thermal utilization efficiency.Moreover,the full range of the solar irradiance can be utilized by incorporating the photocatalytic TiO_(2) layer into the absorber,which is active in the ultraviolet spectral range.In addition to the broadband spectral usage,the virtues of inexpensiveness and environmental friendliness make it a facile alternative to be applied in solar energy transformation.

关键词： absorber photocatalysis multilayer film heat

Advance in Structural Classification and Stability Study of Superamphiphobic Surfaces

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Journal of Bionic Engineering 2023年第1期20卷 366-389页

作者： Haili Zhang Deke Li Jinxia Huang Zhiguang Guo weiming liu Ministry of Education Key Laboratory for the Green Preparation and Application of Functional Materials School of Materials Science and Engineering and Hubei Key Laboratory of Polymer MaterialsHubei UniversityWuhan430062China State Key Laboratory of Solid Lubrication Lanzhou Institute of Chemical PhysicsChinese Academy of SciencesLanzhou730000China School of Materials Engineering Lanzhou Institute of TechnologyLanzhou730050China

Superamphiphobic surfaces have great potential applications in flame resistance,anti-icing,self-cleaning,anti-adhesion,micro-flow control and so on.However,the surface durability is poor owing to the limitation of design principles.In recent years,a lot of efforts have been carried out on the morphology,structure,and stability of superamphiphobic surfaces,resulting in significant improvement in their surface superwetting properties.In this review,we present a brief classification of the morphological types of superamphiphobic surfaces and summary of the recent progress of researches on the stability of superamphiphobic surfaces.Several testing methods of mechanical and chemical stability are listed in the article,together with the characteristic results,to provide a better and more detailed understanding of the current research status on superamphiphobic surface stability,which will be of considerable importance as a reference guide for our future researches.Of course,there are still some issues that need to be addressed for the application of superamphiphobic surfaces at large scale,and this is where our future researches will be directed.Finally,we discuss the challenges as well as the prospects in the study of superamphiphobic surfaces.

关键词： Superamphiphobicity Structure Morphology Stability

Versatile band structure and electron-phonon coupling in layered PtSe_(2) with strong interlayer interaction

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Nano Research 2022年第7期15卷 6613-6619页

作者： Junbo He Xudan Zhu weiming liu Ertao Hu Jianlu Wang Rongjun Zhang Department of Optical Science and Engineering Fudan UniversityShanghai 200433China College of Electronic and Optical Engineering Nanjing University of Posts and TelecommunicationsNanjing 210023China Institute of Optoelectronics Fudan UniversityShanghai 200433China Academy for Engineering and Technology Fudan UniversityShanghai 200433China Yiwu Research Institute of Fudan University Yiwu 322000China

The large tunability in the band structure is ubiquitous in two-dimensional(2D)materials,and PtSe_(2) is not an exception,which has attracted considerable attention in electronic and optoelectronic applications due to its high carrier mobility and long-term airstability.Such dimensional dependent properties are closely related to the evolution of electronic band structures.Critical points(CPs),the extrema or saddle points of electronic bands,are the cornerstone of condensed-matter physics and fundamentally determine the optical and transport phenomena of the layered PtSe_(2).Here,we have experimentally revealed the detailed electronic structures in layered PtSe_(2),including the CPs in the Brillouin zones(BZs),by means of reflection contrast spectroscopy and spectroscopic ellipsometry(SE).There are three critical points in the BZs attributed to the excitonic transition,quasi-particle band gap,and the band nesting effect related transition,respectively.Three CPs show red-shifting trends with increasing layer number under the mechanism of strong interlayer coupling.We have further revealed the electron–phonon(e–ph)interaction in such layered material,utilizing temperature-dependent absorbance spectroscopy.The strength of e–ph interaction and the average phonon energy also decline with the increasement of layer number.Our findings give a deep understanding to the physics of the layer-dependent evolution of the electronic structure of PtSe_(2),potentially leading to applications in optoelectronics and electronic devices.

关键词： layered transition metal dichalcogenides PtSe_(2)thin films interlayer coupling critical points electron-phonon interaction

Direct growth of globally aligned graphene nanoribbons on reconstructed sapphire substrate using PECVD

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Nano Research 2023年第1期16卷 62-69页

作者： Mingzhi Zou weiming liu Yue Yu Shanshan Wang Bo Xu liu Qian Tianze Tong Jin Zhang College of Chemistry and Molecular Engineering Beijing Science and Engineering Center for NanocarbonsBeijing National Laboratory for Molecular SciencesPeking UniversityBeijing 100871China Science and Technology on Advanced Ceramic Fibers and Composites Laboratory College of Aerospace Science and EngineeringNational University of Defense TechnologyChangsha 410000China

Graphene nanoribbons(GNRs)are regarded as an ideal candidate for beyond-silicon electronics.However,synthesis of aligned GNR arrays on insulating substrates with high efficiency is challenging.In this work,we develop a facile strategy,involving KOH pre-treatment and high-temperature annealing,to construct parallel steps on the two-fold symmetry a-plane sapphire substrate.Horizontal GNRs as narrow as 15.1 nm with global alignment across a region of 20 mm^(2)are then grown on the step edgeenriched substrate through plasma enhanced chemical vapor deposition(PECVD)method.GNRs align well along the atomic steps on sapphire([■]direction)with their widths and densities swiftly adjustable by step morphology modification on substrate surface.A step-edge confined growth mechanism is proposed,attributing the constraint on the nanoribbon broadening to a relatively low growth temperature in PECVD,which restrains the activation energy to suppress GNRs across step edges on sapphire and prevents detrimental nanoribbon widening.The results provide a new perspective for scalable synthesizing well aligned nanoribbons of other two-dimensional materials.

关键词： graphene nanoribbon(GNR) global alignment sapphire insulating substrates plasma enhanced chemical vapor deposition(PECVD)

Characteristics of patients with chronic airflow obstruction caused by solid fuel or tobacco smoke

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Chinese Medical Journal 2022年第5期135卷 622-624页

作者： Huanyu Long Zhenzhen Xing Di Chai weiming liu Yaqi Tong Yuxia Wang Yali Ma Mingming Pan Jia Cui Yanfei Guo Department of Respiratory and Critical Care Medicine Beijing HospitalNational Center of GerontologyInstitute of Geriatric MedicineChinese Academy of Medical SciencesBeijing 100730China The Key Laboratory of Geriatrics Beijing Institute of GeriatricsBeijing HospitalNational Center of GerontologyNational Health CommissionInstitute of Geriatric MedicineChinese Academy of Medical SciencesBeijing 100730China Department of Intensive Care Medicine Beijing Boai HospitalBeijing 100068China Rehabilitation Research Center Beijing 100068China

To the Editor: Chronic airflow obstruction (CAO) is a characteristic feature of chronic obstructive pulmonary disease (COPD) and occurs due to airway and/or alveolar abnormalities typically associated with exposure to noxious particles or gases.[1] The major risk factor for CAO is cigarette smoking, but exposure to solid fuel likely influences CAO development. Studies have found that solid fuel exposure is associated with a high prevalence of CAO, particularly among women.[2] Comparing COPD caused by either solid fuel or tobacco smoke exposure is very significant because about 3 billion people are exposed to solid fuel smoke, and 1.01 billion people smoke tobacco, globally. This study aimed to investigate and compare the clinical and functional characteristics of CAO patients exposed to solid fuel and tobacco smoke using propensity score matching (PSM) in western China.

关键词： patients obstruction smoke

Existence of positive solutions with peaks on a Clifford torus for a fractional nonlinear Schrodinger equation

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Science China Mathematics 2019年第9期62卷 1731-1748页

作者： weiming liu Lu Gan School of Mathematics and Statistics Hubei Normal University

We consider the fractional nonlinear Schr?dinger equation in this paper. Applying the finite reduction method, we prove that the equation has positive solutions with peaks on a Clifford torus under some suitable condi... 详细信息

关键词： fractional nonlinear Schrodinger equation reduction method Clifford torus

轨道交通户外站台门与列车间隙背景灯带图像分割算法研究

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铁道标准设计 2024年第4期68卷 178-185页

作者：郑仲星刘伟铭华南理工大学土木与交通学院广州510641

轨道交通在发车前需要清空站台与列车间隙,否则异物入侵会对乘客与列车运行造成安全隐患,基于背景灯带的异物入侵检测需要对灯带在图像中进行图像分割、提取、识别。针对在户外站台场景下,复杂背景和日光等因素为背景灯带提取带来困难... 详细信息

轨道交通在发车前需要清空站台与列车间隙,否则异物入侵会对乘客与列车运行造成安全隐患,基于背景灯带的异物入侵检测需要对灯带在图像中进行图像分割、提取、识别。针对在户外站台场景下,复杂背景和日光等因素为背景灯带提取带来困难的问题,提出一种无监督的图像分割算法。首先通过卷积神经网络进行特征提取,然后将特征图输入到后续分类器中对所有像素进行类别输出。在训练过程中,使用的损失函数从三方面进行设计:考虑特征相似度和空间连续约束、基于深度支持向量描述以及基于几何与光度增强。算法能够实现单样本无监督对神经网络参数进行调优。通过对某城轨站台真实数据采集及实验结果表明,本文提出的方法在与训练样本不同光照条件、拍摄角度条件下,对背景灯带进行分割的F1分数为78.47%;在性能优于其他方法的同时,耗时最多能减少97.1%;算法为基于背景灯带的异物检测方案提供一种行之有效的图像分割方法,为后续的异物自动检测提供基础。

关键词：轨道交通站台间隙异物入侵检测卷积神经网络深度支持向量数据描述无监督图像分割灯带检测

基于快速扩散生成模型的地铁轨道异物入侵检测算法研究

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铁道标准设计 2024年第6期68卷 191-200页

作者：郑仲星刘伟铭华南理工大学土木与交通学院广州510641

针对现有基于无监督的地铁轨道异物检测算法中,对不同视角需要进行单独训练模型的问题,提出一种基于快速扩散生成模型的统一模型检测算法。该模型基于扩散模型,在仅使用正常样本训练一个模型的条件下,实现对多个视角异物入侵检测。检测... 详细信息

针对现有基于无监督的地铁轨道异物检测算法中,对不同视角需要进行单独训练模型的问题,提出一种基于快速扩散生成模型的统一模型检测算法。该模型基于扩散模型,在仅使用正常样本训练一个模型的条件下,实现对多个视角异物入侵检测。检测时,扩散模型对存在异物的图像部分重构为无异物,然后将重构图像和原图进行比对得出存在异物的位置。研究发现,通过合理设计扩散步长和采样时刻,扩散模型能够在不需要扩散过程的情况下,直接对图像中的异常部分进行重构,使其和正常样本一致。为加速扩散模型的采样生成过程,在求解扩散模型的常微分方程的解过程中,分解方程中线性与非线性部分,对线性部分精确求解而对非线性部分进行近似求解。在不添加其他检测网络的条件下,算法利用扩散模型中深度神经网络的编码器部分,对重构图像和原图进行特征提取,在不同尺度上对比两者特征差异,由此得到异常热力图。实验结果表明,该模型在仅需要4次神经网络前馈的条件下,受试者曲线下面积积分比在图像级别和像素级别上分别达到99.05%和97.62%,相比其他单一视角检测模型性能上达到较优水平。本研究为地铁轨道异物检测提出一种仅依赖于正常样本的统一模型的检测算法,能够行之有效地解决已有算法不能对多个视角进行检测的问题。

关键词：地铁轨道异物入侵检测扩散模型统一检测模型异常检测深度学习