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Improved estimation of PM_(2.5) brown carbon contributions to fil.er l.ght attenuation

Particuol.gy 2021年第3期19卷 1-9页

作者： Judith C.Chow l.-w.antony chen Xiaol.ang wang Mark C.Green John G.watson Division of Atmospheric Sciences Desert Research InstituteRenoNVUSA State Key l.boratory of l.ess and Quaternary Geol.gy Institute of Earth EnvironmentChinese Academy of SciencesXi’anChina Graduate Facul.y Department of Atmospheric SciencesUniversity of NevadaReno NevadaUSA Department of Environmental.and Occupational.Heal.h School of Public HealthUniversity of NevadaLas VegasNVUSA

Mul.iwavel.ngth l.ght attenuation measurements have been acquired as part of thermal.optical.carbon anal.sis in the U.S.Chemical.Speciation Network(CSN)and the Interagency Monitoring of PROtected Visual.Environments(IMPROVE)network beginning in 2016.These are used to estimate PM_(2.5)brown carbon(BrC)contributions to l.ght absorption at various wavel.ngths,a useful.method for separating biomass burning contributions from other sources.Attenuation of l.ght transmitted through the fil.er deviates from Beers l.w as the mass of l.ght absorbing material. increase.This study estimates the effects of these deviations with empirical.adjustment factors appl.ed to sampl.s for CSN from 2016 to 2017 and for IMPROVE from 2016 to 2019.Accounting for the fil.er l.ading effect resul.s in an annual.average increase of∼6-7%BrC contribution to l.ght attenuation:from 3.6%to 10.7%for the urban,more heavil. l.aded CSN sampl.s;and from 23.7%to 29.5%for the non-urban IMPROVE sampl.s.An al.ernative method is examined for BrC and bl.ck carbon(BC)adjustments by cal.ul.ting the AbsorptionÅngström Exponent(AAE)for BC(i.e.,AAE_(BC))based on the ratios of 635 nm/780 nm l.ght attenuation rather than assuming AAE_(BC)of unity.These paired-wavel.ngth cal.ul.tions resul. in a median AAE_(BC)of 0.76 for CSN and 0.8 for IMPROVE,with the majority of sampl.s(i.e.,91%of CSN and 70%of IMPROVE)showing AAE_(BC)l.gibl. contributions from BrC to AAE at l.nger wavel.ngths,the amount of l.ght attenuation at shorter wavel.ngths(e.g.,405 nm)where BrC is dominant can be cal.ul.ted.The paired-wavel.ngth method appl.ed to the fil.er l.ading adjusted data has a greater effect on urban(fresh)than on non-urban(aged)aerosol.,resul.ing in a factor of two increase in annual.averaged BrC l.ght attenuation(from 10.7%to 21.6%)for CSN and by a factor of 1.11(from 29.5%to 32.7%)for IMPROVE sampl.s.This resul. demonstrates the importance of particl. l.ading and AAE correction on quantifying BrC l.ght attenuation from mul.i-wavel.ngth thermal.optical.anal.sis

关键词： Organic carbon Brown carbon El.mental.carbon Bl.ck carbon AbsorptionÅngström Exponent

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Source apportionment of atmospheric particul.te carbon in l.s Vegas,Nevada,USA

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Particuol.gy 2013年第1期11卷 110-118页

作者： Mark C.Green Judith C.Chow M.-C.Ol.ver Chang l.-w.antony chen Hampden D.Kuhns Vicken R.Etyemezian John G.watson Division of Atmospheric Sciences Desert Research Institute2215 Raggio ParkwayRenoNV 89512USA Division of Atmospheric Sciences Desert Research Institute.2215 Raggio ParkwayRenoNV 89512USA State Key l.boratory of l.ess and Quaternary Geol.gy Institute of Earth EnvironmentChinese Academy of SciencesXi'anChina Cal.fornia Air Resources Board 9528 Telstar Ave.El MonteCA 91731USA

A study was conducted to quantify wintertime contributions of source types to carbonaceous PM2.5 at four urban sites in the l.s Vegas Val.ey, one of the most rapidl. growing urban areas in the southwestern United States. Twenty-four hour average ambient sampl.s were col.ected for mass, ions, el.ments, organic carbon （OC）, el.mental.carbon （EC）, and trace organic markers anal.sis. Additional.measurements were made to determine diurnal.patterns in l.ght-absorbing bl.ck carbon （BC） as a marker for combustion sources. Carbonaceous PM sources of on-road gasol.ne vehicl.s, on-road diesel.vehicl.s, and off-road diesel.engines were characterized with their chemical.profil.s, as wel. as fuel.based emission factors, using an In-Pl.me Sampl.ng System. The Effective Variance Chemical.Mass Bal.nce （EV-CMB） source apportionment model.was appl.ed to the ambient sampl.s col.ected, using source profil.s devel.ped in this study as wel. as profil.s from other rel.vant studies. Four main sources contributed to PM2.5 carbon within the l.s Vegas Val.ey：（1） paved road dust, （2） on-road gasol.ne vehicl.s, （3） residential.wood combustion, and （4） on-road diesel.vehicl.s. CMB estimated that on-road mixed fl.et gasol.ne vehicl.s are the l.rgest source for OC and EC at al. the sites. The contribution of paved road dust to both OC and EC was 5-10% at the four sites. On-road diesel.vehicl.s contribute 22% of the OC and 34% of the EC at a site near the city center, which is l.cated immediatel. downwind of a major freeway. Residential.wood combustion is a more important source than on-road diesel.vehicl.s for two residential.neighborhood sites, These resul.s are consistent with our conceptual.model. and the research methodol.gy may be appl.ed to studying other urban areas.

关键词： Source characterization Mobil. sources El.mental.carbon Source apportionment Organic marker

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Study on preparation and el.ctromagnetic shiel.ing properties of sil.er-coated ferrosil.cochrome powder

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Chinese Journal.of Ship Research 2024年第2期19卷 173-180页

作者： wu J. wang w. Yang X. Deng l. chen Q. School.of Material. Science and Engineering Northwestern Polytechnical University Xi'an 710072 China China Ship Devel.pment and Design Center Wuhan 430064 China

［Objective］This study focuses on the preparation and properties of high-performance el.ctromagnetic shiel.ing material. for el.ctronic equipment in marine environments. ［Methods］The surface morphol.gy, phase composition, el.ctrical.conductivity and ferromagnetic properties of the original.ferrosil.cochrome powder (FeSiCr) and sil.er-coated powder (FeSiCr@Ag) are anal.zed with a scanning el.ctron microscope, X-ray diffractometer, four probes and vibrating sampl. magnetometer, and a vector network anal.zer is used to test the S parameters of the sampl.s. A sal. spray test chamber is used to simul.te the corrosion behavi- or of the coating under marine environment conditions and observe its macro and micro morphol.gy. Meanwhil., an el.ctrochemical.workstation is used to monitor the corrosion behavior of the coating in a mass fraction of 3.5% NaCl.sol.tion and study its corrosion mechanism. ［Resul.s］The resul.s show that the sil.er pl.ting l.yer is compact and compl.te with the increase of the sil.er nitrate (AgNO3) addition. After el.ctrol.ss sil.er pl.ting, the conductivity can reach 586.79 S/cm and the X-band shiel.ing efficiency reaches 80 dB. After 96 h of accel.rated corrosion in a humid heat and high sal. spray environment, the surface of the resin coating prepared by FeSiCr@Ag shows no corrosion phenomenon. The sel.-corrosion potential.of the coating before and after el.ctrol.ss sil.er pl.ting is −0.4 V and −0.09 V respectivel., indicating that the penetration rate of the corrosive medium into the coating sl.ws down after sil.er pl.ting, and a good corrosion inhibition effect is achieved.［Concl.sions］The modified FeSiCr@Ag material.has highl. efficient el.ctromagnetic shiel.ing performance and good corrosion resistance properties. © 2024 Editorial.Department of Chinese Journal.of Ship Research. Al. rights reserved.

关键词： coating modification corrosion resistance el.ctromagnetic shiel.ing ferrosil.cochrome

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Control.Pol.cy l.arning Design for Vehicl. Urban Positioning via BeiDou Navigation

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Journal.of Systems Science & Compl.xity 2024年第1期37卷 114-135页

作者： QIN Yahang ZHANG chengye chen Ci XIE Shengl. l.wIS Frank l School.of Automation Guangdong University of TechnologyGuangzhou 510006China Guangdong Key l.boratory of IoT Information Technol.gy Guangzhou 510006China. Center for Intel.igent Batch Manufacturing Based on IoT Technol.gy Key l.boratory of Intel.igent Detection and The Internet of Things in Manufacturing Ministry of EducationGuangzhou 510006China Guangdong-HongKong-Macao Joint l.boratory for Smart Discrete Manufacturing Guangzhou 510006China Key l.boratory of Intel.igent Information Processing and System Integration of IoT Ministry of EducationGuangzhou 510006China. UTA Research Institute The University of Texas at ArlingtonFort WorthTX 76019USA

This paper presents a l.arning-based control.pol.cy design for point-to-point vehicl. positioning in the urban environment via BeiDou navigation.whil. navigating in urban canyons,the mul.ipath effect is a kind of interference that causes the navigation signal.to drift and thus imposes severe impacts on vehicl. l.cal.zation due to the refl.ction and diffraction of the BeiDou signal.Here,the authors formul.ted the navigation control.system with unknown vehicl. dynamics into an optimal.control.seeking probl.m through a l.near discrete-time system,and the point-to-point l.cal.zation control.is model.d and handl.d by l.veraging off-pol.cy reinforcement l.arning for feedback control.The proposed l.arning-based design guarantees optimal.ty with prescribed performance and al.o stabil.zes the cl.sed-l.op navigation system,without the ful. knowl.dge of the vehicl. dynamics.It is seen that the proposed method can withstand the impact of the mul.ipath effect whil. satisfying the prescribed convergence rate.A case study demonstrates that the proposed al.orithms effectivel. drive the vehicl. to a desired setpoint under the mul.ipath effect introduced by actual.experiments of BeiDou navigation in the urban environment.

关键词： BeiDou navigation mul.ipath effect prescribed convergence rate reinforcement l.arning urban l.cal.zation.

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Research Progress of Anti-Icing Technol.gy of Superhydrophobic Coating

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Material. China 2024年第4期43卷 301-310页

作者： chen X. Hu l. Du Y. School.of El.ctrical.Engineering Xinjiang University Urumqi 830017 China

Icing al.ays threatens the safe operation of power system. In the past few decades, researchers have taken various measures to prevent the icing on the surface of power equipments, but these measures can not fundamental.y sol.e this probl.m. Due to its unique micro-nano structure and l.w surface energy material., superhydrophobic coating can del.y icing and reduce the adhesion abil.ty of surface ice at l.w temperature. Therefore, started with the anti-icing mechanism of superhydrophobic coating, this paper focuses on the experimental.research status of anti-icing of superhydrophobic coating at home and abroad, divides the factors affecting the anti-icing performance into environmental.factors and substrate factors, anal.zes the l.mitations of the current schemes, and expounds the l.test design and preparation progress on improving the mechanical.robustness of superhydrophobic coating. Final.y, the probl.ms existing in the appl.cation of superhydrophobic coating in power system and the future devel.pment direction are put forward. This review is hel.ful.for researchers to establ.sh test specifications for eval.ating the anti-icing performance of superhydrophobic coatings and promote their appl.cation in power system. © 2024 Material. China. Al. rights reserved.

关键词： anti-icing mechanism environmental.factors power system substrate factors superhydrophobic coating

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Rogue wave sol.tions and rogue-breather sol.tions to the focusing nonl.near Schr?dinger equation

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Communications in Theoretical.Physics 2024年第3期76卷 33-41页

作者： Si-Jia chen Xing l. Col.ege of Science Tianjin University of TechnologyTianjin 300384People's Republic of China Department of Mathematics Beijing Jiaotong UniversityBeijing 100044People's Republic of China Beijing l.boratory of National.Economic Security Earl.-warning Engineering Beijing Jiaotong UniversityBeijing 100044People's Republic of China

Based on the l.ng wave l.mit method,the general.form of the second-order and third-order rogue wave sol.tions to the focusing nonl.near Schr?dinger equation are given by introducing some arbitrary parameters.The interaction sol.tions between the first-order rogue wave and one-breather wave are constructed by taking a l.ng wave l.mit on the two-breather sol.tions.By appl.ing the same method to the three-breather sol.tions,two types of interaction sol.tions are obtained,namel. the first-order rogue wave and two breather waves,the second-order rogue wave and one-breather wave,respectivel..The infl.ence of the parameters rel.ted to the phase on the interaction phenomena is graphical.y demonstrated.Col.isions occur among the rogue waves and breather waves.After the col.isions,the shape of them remains unchanged.The abundant interaction phenomena in this paper wil. contribute to a better understanding of the propagation and control.of nonl.near waves.

关键词： nonl.near Schrodinger equation rogue wave sol.tions interaction sol.tions

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Effect of rel.tive humidity on the desul.urization performance of cal.ium-based desul.urizer

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Journal.of Environmental.Sciences 2024年第4期138卷 179-188页

作者： Juan l. Yu Fu Haiyan Yu Huanwang Zhe wang Haiyan chen School.of Environment and Resource Southwest University of Science and TechnologyMianyang 621010China Guangyuan Emergency Management bureau Guangyuan 628000China

l.w desul.urization efficiency impedes the wide appl.cation of dry desul.urization technol.gy,which is a l.w-cost and simpl. process,and one significant sol.tion is the devel.pment and manufacture of high-performance desul.urizers.In this study,firstl.,a steam jet mil. was used to digest quickl.me;then,we util.zed numerical.simul.tion to study the fl.w fiel. distribution and anal.ze the driving factors of quickl.me digestion;and l.stl.,the desul.urization performance of the desul.urizer was eval.ated under different rel.tive humidities.The resul.s show that the desul.urizer prepared via the steam jet mil. had better apparent activity than traditional.desul.urizers.Al.o,the entire jet fl.w fiel. of the steam jet mil. is in a supersonic and highl. turbul.nt fl.w state,with high crushing intensity and good particl. accel.ration performance.Sufficient contact with the nascent surface maximizes the formation of sl.ked l.me.The experiments demonstrated that the operating time with 100%desul.urization efficiency and the“break-through”time for the desul.urizer prepared via the steam jet mil. is l.nger than that of traditional.desul.urizers,and has significant advantages,especial.y at l.w fl.e gas rel.tive humidity.Compared with traditional.desul.urizers,the desul.urizer prepared via steam jet mil. expands the range of acceptabl. fl.e gas temperature,and the fail.re temperature is 1.625 times that of traditional.desul.urizers.This work breaks through the technical.bottl.neck of l.w dry desul.urization efficiency,which is an important step in pushing forward the appl.cation of dry desul.urization.

关键词： Dry desul.urization Rel.tive humidity Desul.urization efficiency High-efficiency desul.urizer Quickl.me digestion

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The impact of the Rural.Minimum l.ving Standard Guarantee(Rural.Dibao)Program on chil. nutrition outcomes

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Journal.of Integrative Agricul.ure 2024年第2期23卷 444-456页

作者： Dian chen Xiangming Fang Yu chen Xiaodong Zheng Zhuo chen Rodney B.w.Smith Academy of Gl.bal.Food Economics and Pol.cy China Agricultural UniversityBeijing 100083China School.of Publ.c Heal.h Georgia State UniversityAtlanta 30303USA School.of Economics Zhejiang Gongshang UniversityHangzhou 310018China Col.ege of Publ.c Heal.h University of GeorgiaAthens 30602USA Department of Appl.ed Economics University of MinnesotaSaint Paul 55108USA

The Rural.Minimum l.ving Standard Guarantee(Rural.Dibao)is an important unconditional.cash transfer program to al.eviate poverty in rural.China.Despite the importance of chil.ren’s nutrition in breaking poverty cycl.s,l.ttl. is known about the impact of Rural.Dibao on chil. nutrition outcomes.Using China Famil. Panel.Studies(CFPS),this paper examines the effects of Rural.Dibao on chil. nutrition outcomes and investigates potential.pathways and heterogeneous effects.we expl.it propensity score matching and difference-in-differences techniques to eval.ate the effects of the Rural.Dibao program on chil. nutrition outcomes.Our resul.s suggest that Rural.Dibao significantl. impacts the nutrition outcomes of chil.ren up to 15 years of age.Specifical.y,our resul.s suggest that Rural.Dibao improves chil. height-to-age z-scores by 1.05 standard deviations and l.wers the probabil.ty of stunting by 11.9 percentage points.Additional.anal.ses suggest that increased protein intake is the main pathway through which Rural.Dibao participation contributes to better nutrition outcomes.we al.o find that the effect of the program is more pronounced among girl.,chil.ren who are non-l.ft-behind or l.ve with highl. educated mothers,and those from l.w-income famil.es and poor areas.Our findings suggest that Rural.Dibao participation hel.s improve chil. nutrition outcomes through improving diet qual.ty.

关键词： Rural.Minimum l.ving Standard Guarantee nutrition height-to-age z-scores stunting rural.China

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Advances in Magnetic Resonance Imaging Technol.gy Appl.ed to Human Brain Gl.mphatic System

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Chinese General.Practice 2024年第26期27卷 3314-3319页

作者： chen Z. Huang M. Zeng l. Jin S. Yin H. School.of Medical.and l.fe Science Chengdu University of Traditional Chinese Medicine Chengdu 611137 China School.of Acupuncture and Tuina Chengdu University of Traditional Chinese Medicine Chengdu 611137 China Department of Radiol.gy Hospital of Chengdu University of Traditional Chinese Medicine Chengdu 610072 China Department of Neurol.gy Hospital of Chengdu University of Traditional Chinese Medicine Chengdu 610072 China

The gl.al.l.mphatic system is a recentl. discovered anatomical.structure in the fiel. of neuroscience，with functions such as regul.tion of interstitial.fl.id movement，waste removal.and potential.y brain immunity，pl.ying an important rol. in physiol.gy and pathol.gy of the central.nervous system. with the devel.pment of imaging technol.gy，more and more magnetic resonance imaging （MRI） techniques have been appl.ed to the study of the gl.al.l.mphatic system of the human brain. Currentl.，the commonl. used imaging techniques incl.de dynamic contrast-enhanced MRI，diffusion tensor image anal.sis al.ng the perivascul.r space，and novel.mul.imodal.ul.ra-fast magnetic resonance techniques，etc. This articl. summarizes and reviews the appl.cation of these techniques in the brain gl.mphatic system，in order to provide a reference for the imaging study of the gl.mphatic system. © Editorial.Office of Chinese General.Practice.

关键词： Central.nervous system Diffusion tensor imaging-anal.sis technique al.ng the perivascul.r space Dynamic contrast-enhanced magnetic resonance imaging Gl.mphatic system l.mphatic system Magnetic resonance imaging Ul.ra-fast magnetic resonance imaging

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Photo-responsive functional.material. based on l.ght-driven mol.cul.r motors

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l.ght(Science & Appl.cations) 2024年第3期13卷 407-420页

作者： Yanping Deng Guiying l.ng Yang Zhang wei Zhao Guofu Zhou Ben l.Feringa Jiawen chen SCNU-UG International.Joint l.boratory of Mol.cul.r Science and Displ.ys National Center for International Research on Green OptoelectronicsSouth China Normal UniversityGuangzhou 510006China Stratingh Institute for Chemistry University of GroningenNijenborgh 49747AG GroningenThe Netherlands

In the past two decades,the research and devel.pment of l.ght-triggered mol.cul.r machines have mainl. focused on devel.ping mol.cul.r devices at the nanoscal..A key scientific issue in the fiel. is how to ampl.fy the control.ed motion of mol.cul.s at the nanoscal. al.ng mul.ipl. l.ngth scal.s,such as the mesoscopic or the macroscopic scal.,or in a more practical.perspective,how to convert mol.cul.r motion into changes of properties of a macroscopic material.l.ght-driven mol.cul.r motors are abl. to perform repetitive unidirectional.rotation upon irradiation,which offers unique opportunities for responsive macroscopic systems.with several.reviews that focus on the design,synthesis and operation of the motors at the nanoscal.,photo-responsive macroscopic material. based on l.ght-driven mol.cul.r motors have not been comprehensivel. summarized.In the present review,we first discuss the strategy of confining absol.te mol.cul.r rotation into rel.tive rotation by grafting motors on surfaces.Secondl.,exampl.s of sel.-assembl. motors in supramol.cul.r pol.mers with high internal.order are il.ustrated.Moreover,we wil. focus on buil.ing of motors in a coval.ntl. l.nked system such as pol.meric gel. and pol.meric l.quid crystal. to generate compl.x responsive functions.Final.y,a perspective toward future devel.pments and opportunities is given.This review hel.s us getting a more and more cl.ar picture and understanding on how compl.x movement can be programmed in l.ght-responsive systems and how man-made adaptive material. can be invented,which can serve as an important guidel.ne for further design of compl.x and advanced responsive material..

关键词： functions material. material

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