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表面润湿性对核态池沸腾影响的实验研究

工程热物理学报 2019年第3期40卷 635-638页

作者：马强吴晓敏朱毅清华大学能源与动力工程系热科学与动力工程教育部重点实验室北京市CO_2资源利用与减排技术重点实验室北京100084

本文采用化学刻蚀、修饰的方法制备了超亲水、亲水、疏水和超疏水四种不同滤润湿性的表面,以去离子水为工质在常压下对表面核态池沸腾进行可视化实验研究,分析了表面滤润湿性对沸腾换热和对气泡产生、生长、脱离的影响。结果表明:不同... 详细信息

本文采用化学刻蚀、修饰的方法制备了超亲水、亲水、疏水和超疏水四种不同滤润湿性的表面,以去离子水为工质在常压下对表面核态池沸腾进行可视化实验研究,分析了表面滤润湿性对沸腾换热和对气泡产生、生长、脱离的影响。结果表明:不同过热度,表面润湿性对换热系数的影响不同;疏水表面上气泡经竖直拉伸生长过程而长大,并经过短暂的颈缩过程使气泡分为两部分,上部气泡脱离而下部气泡残留在基底上直接进入下一个气泡生长阶段。

关键词：润湿性核态沸腾可视化亲水表面疏水表面

Tunable hexagonal boron nitride topological optical delay line in the visible region

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Chinese Optics Letters 2024年第5期22卷 124-130页

作者：费宏明武敏林瀚杨毅彪肖连团 College of Physics Taiyuan University of TechnologyTaiyuan 030024China College of Information Engineering Shanxi Vocational University of Engineering Science and TechnologyJinzhong 030619China College of Science RMIT UniversityMelbourneVictoria 3000Australia College of Electronic Information and Optical Engineering Taiyuan University of TechnologyTaiyuan 030024China

Tunability,ultracompact design,high group index,low loss,and broad bandwidth are desired properties for integrated optical delay lines(ODLs).However,those properties are challenging to achieve simultaneously in the visible *** paper proposes a tunable hexagonal boron nitride topological optical delay line(ODL)in the visible region based on valley photonic *** topological edge state from the beard-type boundary allows the achievement of an ultralow group velocity close to zero,which results in a large group index of 629 at 645 ***,we demonstrate tuning of the slow-light wavelength and optical delay times with electrically tunable liquid crystals by applying external *** device has an ultracompact size of 5μm×2.7μm with an optical delay distance of 25a(a is the lattice constant)and a delay time of 12 *** design can provide a new possibility for designing ODLs working in the visible region for optical communication and quantum computing systems.

关键词： valley photonic crystal topological edge states optical delay lines

Fractional order distance regularized level set method with bias correction

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The Journal of China Universities of Posts and Telecommunications 2024年第1期31卷 64-82页

作者： Cai Xiumei He Ningning wu Chengmao Liu xiao Liu Hang School of Automation Xi'an University of Posts and TelecommunicationsXi'an 710121China School of Electronic Engineering Xi'an University of Posts and TelecommunicationsXi'an 710121China

The existing level set segmentation methods have drawbacks such as poor convergence,poor noise resistance,and long iteration *** this paper,a fractional order distance regularized level set segmentation method with bias correction is *** method firstly introduces fractional order distance regularized term to punish the deviation between the level set function(LSF)and the signed distance *** a series of covering template is constructed to calculate fractional derivative and its conjugate of image *** introducing the offset correction term and fully using the local clustering property of image intensity,the local clustering criterion of image intensity is defined and integrated with the neighborhood center to obtain the global criterion of image ***,the fractional distance regularization,offset correction,and external energy constraints are combined,and the energy optimization segmentation method for noisy image is established by level *** results show that the proposed method can accurately segment the image,and effectively improve the efficiency and robustness of exiting state of the art level set related algorithms.

关键词： image segmentation fractional order distance regularization level set function fractional derivative bias correction

Evaluation of COVID-19 outbreak prevention and control in Beijing using the emergency management theory

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Fundamental Research 2024年第3期4卷 671-677页

作者： Yu wu Jue Liu min Liu School of Public Health Peking UniversityBeijing 100191China

On April 29,2020,China entered a normalization stage of prevention and *** December 2021,more than 40 outbreaks had occurred in China,which reflected the shortcomings of the pandemic prevention and control measures in China at that *** the capital city of China,Beijing faces more pressure in epidemic prevention and *** used the COVID-19 cluster containment evaluation indicators to determine the effects of prevention and control measures on four COVID-19 outbreaks in *** considering the specificity and operability of evaluation indicators and the availability of evaluation data,the evaluation system in our study consisted of six dimensions:epidemic prevention and control effect,discovery and detection ability,precision prevention and control capability,public protection effect,medical treatment and nosocomial infection prevention and control ability,and information release and public opinion response *** composite scores of the prevention and control effects of the Xinfadi,Shunyi,Daxing,and Ejina Banner–associated COVID-19 outbreaks in Beijing were 62,82,87,and 76,*** the six dimensions,the epidemic prevention and control effect,discovery and detection ability,precision prevention and control capability,and public protection effect scores for the Xinfadi outbreak were lower than those for the Shunyi,Daxing and Ejina Banner–associated *** medical treatment and nosocomial infection prevention and control ability scores for the outbreak associated with Ejina Banner were lower than those for the Xinfadi,Shunyi,and Daxing *** managing cluster outbreaks,Beijing was able to detect index cases early enough to reduce the scale and duration of the outbreak and consistently release official information to reduce public panic,standardize the management of centralized quarantine sites to prevent cross-infection,adhere to the“dynamic COVID‐zero”strategy to accurately prevent and control outbreaks,reduce the societa

关键词： Cluster outbreaks COVID-19 Prevention and control Evaluation Beijing

On the Factors Influencing the High Stretch-Flangeability of a Low-Density 1180 MPa Fe-Mn-Al-C-Nbδ-QP Steel

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Acta Metallurgica Sinica(English Letters) 2024年第8期37卷 1291-1300页

作者： Dan‑Dan Cui Peng Chen Peng‑Fei Wang xiao‑wu Li Department of Materials Physics and Chemistry School of Materials Science and Engineeringand Key Laboratory for Anisotropy and Texture of Materials(Ministry of Education)Northeastern UniversityShenyang 110819China State Key Laboratory of Rolling and Automation Northeastern UniversityShenyang 110819China

Low-densityδ-quenching and partitioning(δ-QP)steels with excellent strength and ductility have been recently ***,there are still rare reports on the formability of δ-QP steels,which are critical for satisfying the manufacture of structural parts during the application in automotive *** the present work,an 1180 MPa Fe–Mn–Al–C–Nbδ-QP steel with a high ductility was adopted for the stretch–flangeability ***δ-QP steel was developed by separated quenching and partitioning processes.A good hole expansion ratio(HER)of 34.9±0.9%was obtained in the quenched steel,but it has been further increased to 52.2%by the tempering *** improved stretch–flangeability was attributed to the enhanced austenite stability and deformation *** the one hand,the stability of austenite was increased by carbon partitioning during tempering,which reduced crack possibility via the suppression of the fresh martensite *** the other hand,the tempering treatment released the internal stress caused by martensitic transformation and reduced the difference in strength among different phases,resulting in an increase in the resistance to crack initiation and propagation.

关键词： Hole expansion ratio Low-densityδ-quenching and partitioning(δ-QP)steel Stretch-flangeability Austenite stability Deformation uniformity

Application value of dexmedetomidine in anesthesia for elderly patients undergoing radical colon cancer surgery

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World Journal of Gastrointestinal Surgery 2024年第8期16卷 2671-2678页

作者： Hui-min Bu min Zhao Hong-Mei Ma xiao-Peng Tian Department of Anesthetic Surgery Qingdao Haici Hospital Affiliated to Qingdao University(Qingdao Hospital of Traditional Chinese Medicine)Qingdao 266033Shandong ProvinceChina

BACKGROUND Colon cancer presents a substantial risk to the well-being of elderly people *** advancements in medical technology,surgical treatment has become the primary approach for managing colon cancer ***,due to age-related physiological changes,especially a decline in cognitive function,older patients are more susceptible to the effects of surgery and anesthesia,increasing the relative risk of postoperative cognitive dysfunction(POCD).There-fore,in the surgical treatment of elderly patients with colon cancer,it is of pa-ramount importance to select an appropriate anesthetic approach to reduce the occurrence of POCD,protect brain function,and improve surgical success *** One hundred and seventeen patients with colon cancer who underwent elective surgery under general anesthesia were selected and divided into two groups:A and *** A received Dex before anesthesia induction,and B group received an equivalent amount of normal *** in the mini-mental state exami-nation,regional cerebral oxygen saturation(rSO2),bispectral index,glucose uptake rate(GluER),lactate production rate(LacPR),serum S100βand neuron-specific enolase(NSE),POCD,and adverse anesthesia reactions were compared between the two *** Surgical duration,duration of anesthesia,and intraoperative blood loss were comparable between the two groups(P>0.05).The overall dosage of anesthetic drugs used in group A,including propofol and remifentanil,was significantly lower than that used in group B(Pmin after the start of surgery,and immediately after extubation,higher GluER values and lower LacPR values at the time of endotra-cheal intubation,30 min after the start of surgery,immediately after extubation,and 5 min after extubation(P<0.05).Group A exhibited lower levels of serum S100βand NSE 24 h postoperatively and a lower incidence of cognitive dysfunction on the 1st and

关键词： Colon cancer Dexmedetomidine General anesthesia Elderly Radical colon cancer surgery Bispectral index Cognitive function Regional cerebral oxygen saturation

Paleoenvironmental reconstruction and organic matter accumulation of the paleogene shahejie oil shale in the Zhanhua Sag, Bohai Bay Basin, Eastern China

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Petroleum Science 2024年第3期21卷 1552-1568页

作者： xiao-Lin Wang xiao-min Zhu Jin Lai Xing-Yue Lin Xiang Wang Yu-Shan Du Chao Huang Yu-Rui Zhu State Key Laboratory of Petroleum Resources and Engineering China University of Petroleum(Beijing)Beijing102249China College of Geosciences China University of Petroleum(Beijing)Beijing102249China Shengli Oilfield SINOPECDongying257000ShandongChina

The controlling factors of organic-rich shale accumulation is essential for the exploration and development of shale oil and gas *** sedimentary environment plays a vital role in the formation of organic-rich sediments in lacustrine *** article unravels the mineralogy,geochemistry,and paleoenvironmental evolution during the deposition of the Paleogene Shahejie Formation(Es_(3)^(L)).It discusses the effects of paleoclimate,paleosalinity,paleoredox conditions,paleowater depth,and paleoproductivity on organic matter(OM)***,the OM enrichment model was *** results show that the mineralogical compositions are mainly composed of calcite(avg.40.13%),quartz(avg.21.64%)and clay minerals(avg.24.07%),accompanied by dolomite(avg.7.07%),feldspar(avg.6.36%)and pyrite(avg.2.95%).The Es_(3)^(L) shale has a high abundance of OM,with total organic carbon(TOC)ranging from 1.07%to 5.12%.The organic matter type is mainly composed of type I-II_(1) kerogen,which is generally considered a good-quality source *** source of OM is a mixture of lower bacteria,algae,and *** the early sedimentary period,the paleoclimate was dry and cold,with high salinity,intense reducibility,and relatively low *** the late sedimentary period,the climate became warmer and more *** a result,the salinity decreased to a level that was suitable for biological reproduction,and productivity increased gradually due to the input of terrigenous *** and paleoclimate determined the environment of the sedimentary period,in addition,paleoproductivity and paleoredox condition indicated the formation and preservation conditions of *** warm and humid climate,brackish water,suitable reduction conditions and high productivity are the favorable conditions for the generation and preservation of organic *** research results may have implications for the genetic mechanisms of organic matter *** will provide theoret

关键词： Elemental geochemical Paleoenvironment Organic matter accumulation Paleogene shahejie formation Zhanhua Sag Bohai Bay Basin

Statistical study of magnetic holes in the upstream region of Mercury’s bow shock

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Earth and Planetary Physics 2024年第2期8卷 326-337页

作者： GuoQiang Wang SuDong xiao mingYu wu YuanQiang Chen TieLong Zhang Institute of Space Science and Applied Technology Harbin Institute of TechnologyShenzhen 518055China Shenzhen Key Laboratory of Numerical Prediction for Space Storm Harbin Institute of TechnologyShenzhen 518055China Mengcheng National Geophysical Observatory University of Science and Technology of ChinaHefei 230026China Chinese Academy of Sciences Center for Excellence in Comparative Planetology Hefei 230026China Space Research Institute Austrian Academy of SciencesGrazAustria

Magnetic holes are magnetic depression structures that exist widely in many plasma *** magnetic holes with durations of>1 s in the solar wind at Mercury’s orbit have drawn much attention,but the properties of the magnetic holes with shorter durations are still ***,we investigate the magnetic holes with durations of 0.1-100 s in the upstream region of Mercury’s bow shock based on observations by the MESSENGER(MErcury Surface,Space ENvironment,GEochemistry,and Ranging)*** can be divided into two groups according to the distribution of their duration:small-duration magnetic holes(SDMHs,0.6 s).The duration of each group approximately obeys a log-normal distribution with a median of~0.25 s and 3 s,*** 1.7%(32.6%)of the SDMHs(LDMHs)reduce the magnetic field strength by more than 50%.For both groups,some structures have a linear or quasi-linear polarization,whereas others have an elliptical *** magnetic hole events in both groups tend to have a higher rate of occurrence when the interplanetary magnetic field strength is *** occurrence rates are also affected by Mercury’s foreshock,which can increase(decrease)the occurrence rate of the SDMHs(LDMHs).This finding suggests that Mercury’s foreshock might be one source of the SDMHs and that the foreshock can destroy some *** observations suggest that a new group of magnetic holes with durations of<0.6 s exist in the upstream region of Mercury’s bow shock.

关键词： magnetic hole solar wind Mercury foreshock

Identification of high oxygen-consuming substances in stormwater drainage systems illicitly connected with sewage system

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Journal of Environmental Sciences 2024年第4期138卷 132-140页

作者： Chen Xu Zuxin Xu Wenhai Chu Shanshan wu Rong xiao Lei Su State Key Laboratory of Pollution Control and Resource Reuse College of Environmental Science and EngineeringTongji UniversityShanghai 200092China ministry of Education Key Laboratory of Yangtze River Water Environment Tongji UniversityShanghai 200092China Guangzhou Resource Environmental Protection Technology Co. Ltd.Guangzhou 510030China

The dissolved oxygen content in water is an important indicator for assessing the quality of the water environment,and maintaining a certain amount of dissolved oxygen is essential for the healthy development of the ecological *** a water body is anoxic,the activity of anaerobic microorganisms increases and organic matter is decomposed to produce a large number of blackening and odorizing substances,resulting in black and odorous water bodies,which is a very common and typical phenomenon in ***,there is still a relatively universal occurrence of illicitly connected stormwater and sewage pipes in the urban drainage pipe network in China,which makes oxygen-consuming substances be directly discharged into rivers through stormwater pipes and consume the dissolved oxygen in the water bodies,resulting in an oxygen deficiency of the *** induces seasonal or year-round black and stink phenomena in urban ***,identifying high oxygen-consuming substances,which lays the foundation for the subsequent removal of oxygen-consuming substances,is *** a series of comparisons of water quality indicators and analysis of organic characteristics,it was found that the oxygen consumption capacity of domestic sewage was higher than that of industrial wastewater in the selected area of this study,and the oxygen-consuming substances of domestic sewage were small molecular amino *** comparing 20 conventional free amino acids,it was found that seven of them consumed oxygen easily,and compared with chemical oxygen consumption,biological oxygen consumption was in a leading position.

关键词： Urban drainage system Oxygen-consuming substances Domestic sewage Amino acid