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Influence of biomass burning on ozone levels in the Megalopolis of Central Mexico during the COVID-19 lockdown

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j.urnal of Environmental Sciences 2024年第9期143卷 99-115页

作者： Victor Almanza Luis Gerardo Ruiz-Suárez Ricardo Torres-j.rdón Agustín García-Rey.oso Iván y.Hernández-Paniagua Institute for Atmospheric Sciences and Climate Change National Autonomous University of MexicoCoyoacan 04510Mexico CityMexico

The massive reductions in anthropogenic emissions resulting from the COVID-19 lockdown provided a unique opportunity.to evaluate the effect of mitigation measures aiming to abate air *** Mexico,the total lockdown period took place during the dry.hot season when biomass burning activity.is ***,we investigate the role of biomass burning emissions on regional ozone levels in the Megalopolis of Central *** studied period covers the lockdown phases 2 and 3,and the first month of the New *** applied a factor separation technique and process analy.is to estimate the pure and sy.ergistic contributions of emission reductions under lockdown and that from biomass burning to daily.ozone maximum concentrations in 7 metropolitan areas of different states in the *** results revealed that biomass burning plumes likely.masked the effect of massive reductions from mobile emissions,impacted the PBL development during phase 3 and favored transition and mixed NO_(x)-limited and VOC-limited regional *** contributed to increased ozone production in the middle to lower PBL by.changing the regional background levels which potentially.could bias high ozone production efficiency.*** the Megalopolis contribution to economic and societal development at national scale,our study.suggests that ozone mitigation measures during the dry.hot season targeting mainly.mobile emissions will likely.be offset by.biomass burning plumes.A regional and sy.ergic policy.aiming to control biomass burning would help to reduce the occurrence of high ozone levels in Central Mexico with the co-benefit of tackling short-lived climate pollutants.

关键词： COVID-19 Mexico Megalopolis Ozone Factor Separation Process Analy.is

First-Principles Study.of the Influence of Lattice Misfit on the Behavior and the Ductility.Effect of Hafnium in Ni-Ni3AI Sy.tem

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Acta Metallurgica Sinica(English Letters) 2014年第1期27卷 87-94页

作者： y. Wu j. Guo W. Zhang X. Ma Q. Zhang j. Hou R. Huang X. Liu Institute of Molecular Engineering and Applied Chemistry Anhui University of Technology Ma'anshan 243002 China Sheny.ng National Laboratory.for Materials Science Instituteof Metal Research Chinese Academy of SciencesShenyang 110016 China College of Phy.ics Science and Technology Shenyang NormalUniversity Huanghe Street 253 Shengyang 110034 China School of Materials Science and Engineering Anhui Universityof Technology Ma'anshan 243002 China

Two Ni/Ni3Al-interface-contained cluster models with/without lattice misfit are studied by.first-principles method to clarify.the debates about the segregation behaviors of Hafnium （Hf） and explore the influence of lattice misfit on the ductility.effect of Hr. It is found that though Hf prefers to substitute A1 rather than Ni in Ni3A1 phase within most of the investigated misfit range, its stronger preferring to Ni phase than NiaA1 phase makes it impossible to go into Ni3A1 phase to occupy.A1 site in Ni-Ni3A1 alloy.. Bond order analy.is in Hf-free case shows that lattice misfit has different effects on the Griffith work of interfacial cleavage 27int/E and the maximum theoretical shear stress Zmax of Ni and Ni3A1, contributing to the existence of anomalous strength-temperature phenomena in NiaA1 alloy.. However, the addition of Hf will make the 27int/E （or Zmax） of both Ni3A1 and Ni decrease （or increase） with lattice misfit, indicating that the addition of Hf may.make the anomalous strength-temperature relationship in Ni3A1 region disappear locally.

关键词： Hafnium Lattice misfit Segregation Ductility

基于状态空间模型的激光再制造熔池温度控制系统

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表面工程与再制造 2024年第2期24卷 50-50页

作者： y.ng G.-Z. Liu T.-M. Song B.-X. j.ang X.-y. Wang Z.-S. Chen K.-Q. Liu W.-j. School of Mechanical Engineering Shenyang University of Technology Shenyang China

激光再制造是用于再制造的一项重要技术,在航空航天、冶金、能源等领域应用广泛。然而,形状控制问题一直是制约其规模化和工业化应用的瓶颈。在激光再制造过程中,熔池温度是决定再制造件形状和性能稳定性的关键。基于此,本文提出了一种... 详细信息

激光再制造是用于再制造的一项重要技术,在航空航天、冶金、能源等领域应用广泛。然而,形状控制问题一直是制约其规模化和工业化应用的瓶颈。在激光再制造过程中,熔池温度是决定再制造件形状和性能稳定性的关键。基于此,本文提出了一种基于状态空间模型的激光再制造熔池温度实时在线控制方法,解决了控制机理模型难以建立和多变量约束的问题。

关键词：状态空间模型激光再制造熔池温度航空航天形状控制控制系统变量约束性能稳定性

PROPERTIES OF THREE-DIMENSIONAL MOVEMENT OF SANDy.WATER DISCHARGED INTO A LAKE

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j.urnal of Hy.rody.amics 2001年第2期13卷 72-76页

作者： Deng, y. Li, j. Li, K.F. Zhao, W.Q. State Key.Lab. of High Speed Flow Sichuan Univ. Chengdu 610065 China

A Random Traj.ctory.Model (RTM) for solid-liquid two-phase flow based on the Lagrangian Method is presented in this paper. The effects of water drag force, pressure gradient force, buoy.ncy.and virtual mass force on the particles were included and the turbulent dispersion was modeled by.random method. Three-dimensional k-Ε model was used to calculate the flow field. A pumped-storage power station, with a natural lake as its upper pool, was taken as a case for the study. Averaged movement traj.ctories, velocities and the volume-concentration distributions for 5 groups of sediment particles, were predicted with RTM. The possible silted locations in the lake were also predicted.

关键词： Boundary.conditions Computer simulation Lakes Sand Three dimensional Two phase flow Velocity

Bidirectional Erbium Doped Fiber Amplifiers

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High Technology.Letters 1995年第1期1卷 66-70页

作者： Zhong, C. Peixuan, j. Ling, L. Peida, y. Beij.ng Univ of Posts and Telecommunications Beijing China

Bidirectional EDFAs(Bi-EDFAs)featuring bidirectional signal input are *** and noise performances of Bi-EDFAs are analy.ed numerically.and comparedwith that of other optical *** of Bi-EDFAs in fiber networks and otherf... 详细信息

关键词： Erbium doped fiber amplifiers ASE Bidirectional optical amplifiers

A Statistical Analy.is of Point-like Sources in the Chandra Galactic Center Survey

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Chinese j.urnal of Astronomy.and Astrophy.ics 2007年第1期7卷 81-90页

作者： j. E Wu S. N. Zhang F.j. Lu y. K. j.n Department of Phy.ics and Center for Astrophy.ics Tsinghua University Beijing 100084 Key.Laboratory.of Particle Astrophy.ics Institute of High Energy Physics Chinese Academy ofSciences Beijing 100049 Department of Engineering Phy.ics and Center for Astrophy.ics Tsinghua University Beijing 100084

The Chandra Galactic Center Survey.detected -800 X-ray.point-like sources in the 2°× 0.8° sky.region around the Galactic Center. We study.the spatial and luminosity.distributions of these sources according to their spectral properties. Fourteen bright sources detected are used to fit j.intly.an absorbed power-law model, from which the power-law photon index is determined to be -2.5. Assuming that all other sources have the same power-law form, the relation between hardness ratio and HI column density.NH is used to estimate the NH values for all sources. Monte Carlo simulations show that these sources are more likely.concentrated in the Galactic center region, rather than distributed throughout the Galactic disk. We also find that the luminosities of the sources are positively.correlated with their HI column densities, i.e., a more luminous source has a higher HI column density. From this relation, we suggest that the X-ray.luminosity.comes from the interaction between an isolated old neutron star and interstellar medium （mainly.dense molecular clouds）. Using the standard Bondi accretion theory.and the statistical information of molecular clouds in the Galactic center, we confirm this positive correlation and calculate the luminosity.range in this scenario, which is consistent with the observation （10^32 - 10^35 erg s^-1）.

关键词： methods data analy.is-Galaxy center-X-ray stars

Fluctuating hy.rody.amic methods for fluid-structure interactions in confined channel geometries

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Applied Mathematics and Mechanics(English Edition) 2018年第1期39卷 125-152页

作者： y. WANG H. LEI P.j. ATZBERGER Department of Mathematics University of California Santa Barbara Santa Barbara CA 93106 U. S. A. Pacific Northwestern National Laboratories Richland WA 99354 U. S. A.

We develop computational teractions subj.ct to thermal fluctuations geometry. The methods take into account methods for the study.of fluid-structure in- when confined within channels with slit-like the hy.rody.amic coupling and diffusivity.of microstructures when influenced by.their proximity.to no-slip walls. We develop stochas- tic numerical methods subj.ct to no-slip boundary.conditions using a staggered finite volume discretization. We introduce techniques for discretizing stochastic sy.tems in a manner that ensures results consistent with statistical mechanics. We show how an exact fluctuation-dissipation condition can be used for this purpose to discretize the stochastic driving fields and combined with an exact proj.ction method to enforce incompressibil- ity. We demonstrate our computational methods by.investigating how the proximity.of ellipsoidal colloids to the channel wall affects their active hy.rody.amic responses and passive diffusivity. We also study.for a large number of interacting particles collective drift-diffusion dy.amics and associated correlation h/actions. We expect the introduced stochastic computational methods to be broadly.applicable to applications in which con- finement effects play.an important role in the dy.amics of microstructures subj.ct to hy.rody.amic coupling and thermal fluctuations.

关键词： fluctuating Eulerian-Lagrangian method hy.rody.amics immersed (SELM) ellipsoidal colloid boundary.method stochastic mobility nanochannel

Effect of Bismuth on Intermetallic Compound Growth in Lead Free Solder/Cu Microelectronic Interconnect

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j.urnal of Materials Science & Technology 2011年第8期27卷 741-745页

作者： T.y. Kang y. y. Xiu L. Hui j.j. Wang W.P. Tong C.Z. Liu Key.Laboratory.of Electromagnetic Processing of Materials Ministry of Education Northeastern University Shenyang 110004 China Sheny.ng Aerospace University Shenyang 110136 China

The intermetallic compound （IMC） growth kinetics in pure Sn/Cu and Sn10 wt%Bi/Cu solder j.ints was studied, respectively. after they.were aged at 160-210℃ for different time. It was found that the total IMC in Sn10 wt%Bi/Cu j.int developed faster than it did in pure Sn/Cu solder j.int, when they.were aged at the same temperature. And the activation energy.Qa for total IMC in Sn10 wt%Bi/Cu j.int was lower than that for pure Sn/Cu interconnect. The IMC growth process was discussed. The IMC Cu6Sn5 was enhanced in compensation of reduced IMC Cu3Sn growth. The work reveals that Bi element containing in lead free solder alloy. with 10 wt% can enhance IMC growth in lead free solder/Cu j.int during service.

关键词： Solder Interfacial reaction Intermetallics Kinetics

Decorating cry.talline y.e_(2-x)Al_(x) on the Mg_(60)La_(10)Ni_(20)Cu_(10) amorphous alloy.as “hy.rogen pump” to realize fast de/hy.rogenation

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j.urnal of Materials Science & Technology 2024年第6期173卷 72-79页

作者： L.j.Huang H.Wang L.Z.Ouy.ng M.Zhu H.j.Lin School of Materials Science and Engineering Key Laboratory of Advanced Energy Storage Materials of Guangdong ProvinceSouth China University of TechnologyGuangzhou 510641China Institute of Advanced Wear&Corrosion Resistance and Functional Materials Jinan UniversityGuangzhou 510632China

Mg-based amorphous alloy. are one of the potential hy.rogen storage materials but suffer from sluggish dehy.rogenation/hy.rogenation(de/hy.rogenation)*** this work,as a new strategy.a hy.rogen pump is built on the surface of amorphous alloy. to solve this *** milling cry.talline y.e_(2-x)Al_(x) hy.rogen storage alloy.with Mg_(60)La_(10)Ni_(20)Cu_(10) amorphous alloy.fine cry.talline particles were seeded on amorphous alloy.powder to form a“strawberry.*** to the TEM observation,a metallurgical bonding boundary.formed between the Mg-based amorphous matrix and the y.Fe-Al cry.talline *** microstructure and de/hy.rogenation kinetics investigation,the“hy.rogen pump”effect of the seeded cry.talline alloy.was confirmed,which makes it much easier for the hy.rogen to dissociate on and diffuse through the surface of the Mg-based amorphous *** such effect,the H absorption rate of Mg_(60)La_(10)Ni_(20)Cu_(10) amorphous alloy.became almost eight times faster and it absorbs ~2.8 wt.% in 1 h at 130℃ under 4.5 MPa-H_(2).Further,fast hy.rogenation can even achieve at 70℃ and the low-temperature dehy.rogenation kinetics of the amorphous hy.ride can be also greatly.*** present work proves that surface modification is of great importance for obtaining Mg-based amorphous alloy.with ideal hy.rogen storage performance.

关键词： Hy.rogen storage Mg-based amorphous alloy Hy.rogen pump Composite structure