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The Short-Duration Heavy Rainfall in Different Quadrants of Northeast China Cold Vortices

journal of Meteorological Research 2024年第2期38卷 321-338页

作者： lei YANG Yongguang ZHENG Liaoning Meteorological Disaster Monitoring and Early Warning Center Shenyang 110166 National Meteorological Centre China Meteorological AdministrationBeijing 100081 China Meteorological Administration Tornado Key Laboratory Foshan 528315

The Northeast China cold vortex(NCCV)is one of the main synoptic-scale systems causing short-duration heavy rainfall(SDHR)in Northeast *** conditions(e.g.,water vapor,instability,and vertical wind shear)are known to be distinctly different over the four quadrants of NCCVs,rendering prediction of the SDHR related to NCCVs(NCCV_SDHR)more *** on 5-yr hourly rainfall observations from 3196 automatic weather stations and ERA5 reanalysis data,10,232 NCCV_SDHR events were identified and divided into four quadrant groups according to their relative position to the center of the NCCV(CVC).The results show that the southeast quadrant features the highest frequency of SDHR,with stronger intensity,longer duration,and wider coverage;and the SDHR in different quadrants presents different formation mechanisms and varied temporal evolution.A new coordinate system is established relative to the CVC that uses the CVC as the origin and the radius of the NCCV(r CV)as the unit *** this new coordinate system,all of the NCCV_SDHR events in the 5-yr study period are *** is found that the occurrence frequency of NCCV_SDHR initially increases and then decreases with increasing distance from the *** highest frequency occurs mainly between 0.8 and 2.5 times r CV from the CVC in the southeast *** can be attributed to the favorable conditions,such as convergence of the low-level shear line and abundant water vapor,which are concentrated in this ***,high-frequency NCCV_SDHR larger than 50 mm(NCCV_SDHR50)is observed to be closer to the *** NCCV_SDHR50occurs,the NCCV is in closer proximity to the subtropical high,resulting in stronger low-level convergence and more abundant water ***,there are lower lifting condensation levels and stronger 0-6-and 0-1-km vertical wind shears in these *** findings provide a valuable reference for more accurate prediction of NCCV_SDHR.

关键词： Northeast China cold vortex short-duration heavy rainfall statistical characteristics environmental conditions

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Proteomic response of Phaeocystis globosa to nitrogen limitation

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journal of Oceanology and Limnology 2024年第1期42卷 141-149页

作者： Haisu LIU Ruiwang WEI Qiangyong lei lei CUI Songhui LÜ Key Laboratory of Eutrophication and Red Tide Prevention Research Center for Harmful Algae and Marine BiologyJinan UniversityGuangzhou 510632China Southern Marine Science and Engineering Guangdong Laboratory Zhuhai 519082China National Engineering Laboratory of Electronic and Information Standardization Shenzhen 518057China

Phaeocystis globosa is an important unicellular eukaryotic alga that can also form *** can cause massive harmful algal blooms and plays an important role in the global carbon or sulfur *** far,the ecophysiology of *** has been investigated by numerous ***,the proteomic response of *** to nitrogen depletion remains largely *** compared four protein preparation methods of *** for two-dimensional electrophoresis(2-DE)(Urea/Triton X-100 with trichloroacetic acid(TCA)/acetone precipitation;TCA/acetone precipitation;Radio Immuno Precipitation Assay(RIPA)with TCA/acetone precipitation;and Tris buffer).Results show that the combination of RIPA with TCA/acetone precipitation had a clear gel background and showed the best protein spot separation effect,based on which the proteomic response to nitrogen depletion was studied using *** addition,we identified six differentially expressed proteins whose relative abundance increased or decreased more than 1.5-fold(P<0.05).Most proteins could not be identified,which might be attributed to the lack of genomic sequences of *** nitrogen limitation,replication protein-like,RNA ligase,and sn-glycerol-3-phosphate dehydrogenase were reduced,which may decrease the DNA replication level and ATP production in *** *** increase of endonucleaseⅢand transcriptional regulator enzyme may affect the metabolic and antioxidant function of *** cells and induce cell *** findings provide a basis for further proteomic study of *** and the optimization of protein preparation methods of marine microalgae.

关键词： Phaeocystis globosa nitrogen limitation proteomic response two-dimensional electrophoresis

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Corrosion behavior of Gd_(2)Zr_(2)O_(7)thermal barrier coatings under Fe-containing environmental sediment attack

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journal of Advanced Ceramics 2024年第4期13卷 447-462页

作者： lei Guo Yanyan Li Kai Yan School of Materials Science and Engineering Tianjin UniversityTianjin 300072China Tianjin Key Laboratory of Advanced joining Technology Key Lab of Advanced Ceramics and Machining Technology of Ministry of EducationTianjin 300072China Key Laboratory of Special Equipment Safety and Energy-saving for State Market Regulation China Special Equipment Inspection&Research InstituteBeijing 100029China

Environmental sediments mainly consisting of CaO–MgO–Al_(2)O_(3)–SiO_(2)(CMAS)corrosion are a serious threat to thermal barrier coatings(TBCs),in which Fe element is usually ***_(2)Zr_(2)O_(7)TBCs are famous for their excellent CMAS *** this study,the characteristics of Fe-containing environmental sediments(CMAS-Fe)and their corrosiveness to Gd_(2)Zr_(2)O_(7)coatings were *** types of CMAS-Fe glass with different Fe contents were *** melting points were measured to be 1322–1344℃,and the high-temperature viscosity showed a decreasing trend with increasing Fe *** corrosion behavior of four types of CMAS-Fe to Gd_(2)Zr_(2)O_(7)coatings at 1350℃was *** the initial corrosion stage(0.1 h),anorthite was precipitated in CMAS-Fe with a high Ca:Si ratio,while Fe-garnet was formed in the melt with the highest Fe *** the corrosion time resulted in the formation of a reaction layer,which exhibited an interpenetrating network composed of Gd-oxyapatite,ZrO_(2),and residual *** spinel was precipitated within the reaction *** 1 h or even longer time,the reaction layers tended to be stable and compact,which had comparable hardness and fracture toughness to those of Gd_(2)Zr_(2)O_(7)*** the cyclic CMAS-Fe attack,the residual CMAS-Fe in the interpenetrating network provided a pathway for the redeposited CMAS-Fe infiltration,resulting in the continuous growth of the reaction *** a result,the Gd_(2)Zr_(2)O_(7)coatings had a large consumption in the thickness,degrading the coating ***,the Gd_(2)Zr_(2)O_(7)coatings exhibit unsatisfactory corrosion resistance to CMAS-Fe attack.

关键词： thermal barrier coatings(TBCs) Gd_(2)Zr_(2)O_(7) Fe-containing CaO-MgO-Al2O3-SiO_(2)(CMAS) corrosion resistance reaction layer

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Cobalt-catalyzed reductive alkynylation to construct C(sp)-C(sp^(3))and C(sp)-C(sp^(2))bonds

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Chinese Chemical Letters 2024年第7期35卷 253-258页

作者： lei Wan Yizhou Tong Xi Lu Yao Fu Hefei National Research Center for Physical Sciences at the Microscale iChEMCAS Key Laboratory of Urban Pollutant ConversionAnhui Province Key Laboratory of Biomass Clean EnergyUniversity of Science and Technology of ChinaHefei 230026China Key Laboratory of Precision and Intelligent Chemistry School of Chemistry and Materials ScienceUniversity of Science and Technology of ChinaHefei 230026China

Transition-metal-catalyzed cross-electrophile coupling has emerged as a reliable method for constructing carbon–carbon ***,we report a general method,cobalt-catalyzed reductive alkynylation,to construct C(sp)-C(sp^(3))and C(sp)-C(sp^(2))*** presented reaction has a broad substrate scope,enabling the efficient cross-electrophile coupling between alkynyl bromides with alkyl halides and aryl or alkenyl(pseudo)*** presented reaction is conducted under mild conditions,tolerating many functional groups,thus suitable for the modification and synthesis of biologically active molecules.

关键词： Cobalt-catalysis Cross-electrophile coupling Carbon-carbon bond formation Reductive alkynylation Alkyne synthesis

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Influence of Vanes and Blades on Ingress in Axial Rim Seal for Turbine Stages

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journal of Thermal Science 2024年第3期33卷 833-846页

作者： REN Ran DU Qiang LIU Guang ZENG Yanlian XIE lei Institute of Engineering Thermophysics Chinese Academy of SciencesBeijing100190China National Key Laboratory of Science and Technology on Advanced Light-duty Gas-turbine Beijing100190China School of Aeronautics and Astronautics University of Chinese Academy of SciencesBeijing100190China

Hot gas ingestion refers to the phenomenon of mainstream hot gas flowing into the space cavity of a turbine *** studies have found that mainstream annulus pressure distribution plays an important role in hot gas ingestion,but due to its complexity,the mechanism of the interaction between mainstream flow and hot gas ingestion remains *** paper adopts the URANS method,and three sealing flow rates are considered,named C_(w)=0,C_(w)=500,and C_(w)=*** time-averaged annulus pressure distribution shows that an increase in the sealing flow decreases the pressure value,and the effects of the sealing flow on the pressure distribution of the leading edge of the blade are much more influential than that of the trailing edge of the *** unsteady pressure time-space distribution in the annulus indicates that a time-space tilted distribution of pressure at the rim exits when the sealing flow *** phenomenon is mainly due to the strong feedback mechanism of the sealing flow to the annulus pressure field.A comparison of the pressure and mean radial velocity distribution of the mainstream shows that the ingestion mainly occurs on the blade side,where the pressure is lower than on the vane *** flow characteristics at the wheel rim are analyzed with a sealing flow rate C_(w)=5000,and under these conditions,both pressure-induced ingestion and ingestion caused by a passage vortex can be *** three-dimensional and inertial effects of the mainstream at the wheel rim lead to the generation of separation vortices on the blade side,and the presence of separation vortices leads to ingestion along the blade *** the same time,pressure on the blade side will cause the fluid to have a radial inward flow tendency,which will promote the formation of separation vortices,leading to more serious ingestion in the high-pressure region on the blade *** blade pressure field can be more significant than the vane trailing pressure field in the rim sea

关键词： separation vortex unsteady rim seal the effect of blade on ingestion

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Coexistence of antiferromagnetism and unconventional superconductivity in a quasi-one-dimensional flat-band system:Creutz lattice

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Chinese Physics B 2024年第3期33卷 583-588页

作者：徐峰张磊 School of Physics and Telecommunication Engineering Shaanxi University of TechnologyHanzhong 723001China

We study the coexistence of antiferromagnetism and unconventional superconductivity on the Creutz lattice which shows strictly flat bands in the noninteracting *** famous renormalized mean-field theory is used to deal with strong electron-electron repulsive Hubbard interaction in the effective low-energy t-j model,the superfluid weight of the unconventional superconducting state has been calculated via the linear response *** unconventional superconducting state with both spin-singlet and staggered spin-triplet pairs emerges beyond a critical antiferromagnetic coupling interaction,while antiferromagnetism accompanies this *** superconducting state with only spin-singlet pairs is dominant with paramagnetic *** A phase is analogous to the pseudogap phase,which shows that electrons go to form pairs but do not cause a *** also show the superfluid behavior of the unconventional superconducting state and its critical *** is proven directly that the flat band can effectively raise the critical temperature of *** is implementable to simulate and control strongly-correlated electrons'behavior on the Creutz lattice in the ultracold atoms experiment or other artificial *** results may help the understanding of the interplay between unconventional superconductivity and magnetism.

关键词： flat-band unconventional superconductivity antiferromagnetism strong electron-electron interaction superfluid weight

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Significant annealing-induced hardening effect in nanolaminate d-nanotwinne d(CrCoNi)_(97.4)Al_(0.8)Ti_(1.8)me dium-entropy alloy by severe cold rolling

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journal of Materials Science & Technology 2024年第3期170卷 156-166页

作者： Shuqing Yuan Hui Fu lei Qian Chi Fai Cheung Xu-Sheng Yang State Key Laboratory of Ultra-precision Machining Technology Department of Industrial and Systems EngineeringThe Hong Kong Polytechnic UniversityHung HomKowloonHong KongChina Hong Kong Polytechnic University Shenzhen Research Institute Shenzhen 518060China

Due to the easy coarsening caused by poor thermal stability,the verified annealing-induced hardening in nanograined metals can only maintain at a relatively low-temperature *** this study,a nanolam-inated(CrCoNi)_(97.4)Al_(0.8)Ti_(1.8)medium-entropy alloy with an average lamellae thickness of∼20 nm embedded by thinner nanotwins was fabricated by severe cold rolling to achieve superior thermal *** with the conventional nanotwinned CrCoNi with nanotwins inside ultra-fined grains,the hier-archical nanolaminated-nanotwinned(CrCoNi)_(97.4)Al_(0.8)Ti_(1.8) exhibits a significant annealing-induced hard-ening effect,i.e.,hardness increasing from∼250 HV in the original specimen to∼500 HV in the cold-rolled status and finally∼630 HV after annealing at 600℃for 1 *** microstructure characterizations reveal that the reduced dislocation density and formation of L1_(2)ordered domain are mainly responsible for such hardening effect,which is facilitated by the effectively suppressed coarsening with annealing temperature,i.e.,slow detwinning process and well-retained low-angle nanolamellar *** coarsening mechanisms from the cold-rolled nanolamellae to the fully recrystallized micro-equiaxed structures under the annealing temperatures ranging from 400 to 800℃ were also elucidated by atomic observations.

关键词： Annealing-induced hardening Thermal stability Nanolaminated-nanotwinned structure CrCoNi Detwinning Grain boundary migration

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Fluid-structure interaction simulation of dynamic response and wake of floating offshore wind turbine considering tower shadow effect

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Acta Mechanica Sinica 2024年第8期40卷 67-84页

作者： Songyang Liu Zhiqiang Xin lei Wang Zhiming Cai College of Mechanics and Engineering Science HoHai UniversityNanjing211100China

The comprehensive numerical simulation of the tower shadow effect on floating offshore wind turbines(FOWTs),an area less explored compared to fixed-bottom wind turbines,is presented in this *** atmospheric boundary layer inflow and the joint north sea wave project random wave are used as the operating conditions for *** combination of computational fluid dynamics(CFD)software simulator for wind farm applications and turbine simulation tool OpenFAST is used to implement fluid-structure interaction *** output power,platform motion,wake velocity deficit and vortex structures are analyzed to reveal the influence of the tower shadow effect on the *** results indicate that due to the fluctuation caused by the turbulent wind and the floating platform motion,the tower shadow effect of FOWT is less significant for its periodic power decay than that of fixed-bottom wind *** according to the velocity deficit analysis,the influence area of the tower shadow effect on the wake is mainly in the near wake region.

关键词： Floating offshore wind turbine Tower shadow effect Atmospheric boundary layer inflow jONSWAP wave Wind turbine wake

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Enhancing hydrolytic stability of dynamic imine bonds and polymers in acidic media with internal protecting groups

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Chinese Chemical Letters 2024年第5期35卷 161-165页

作者： Hang Chen Chengzhi Cui Hebo Ye Hanxun Zou lei You College of Environmental and Biological Engineering Fujian Provincial Key Laboratory of Ecology-Toxicological Effects&Control for Emerging ContaminantsPutian UniversityPutian 351100China State Key Laboratory of Structural Chemistry Fujian Institute of Research on the Structure of MatterChinese Academy of SciencesFuzhou 350002China College of Chemistry and Material Science Fujian Normal UniversityFuzhou 350007China Fuj.an Science&Technology Innovation Laboratory for Optoelectronic Information of China Fuzhou 350108China

Imine bonds are among the most explored building motifs in dynamic chemistry,polymers,and materials,and yet,their acid-resistance remains a longstanding *** we demonstrate a concept of internal protecting groups for improving the kinetic stability of dynamic imine bonds and *** examination of structure-reactivity relationship of a series of aldehydes/imines bearing a neighboring carboxyl allowed uncovering of required structural features for dynamically masking imine bonds with cyclic *** studies indicated that noncovalent interactions along with sterics control the ringchain equilibrium and the stability of imine *** incorporation of internal protecting groups into imine polymers further enabled their controlled stability in acidic ***,a combination of dynamic covalent network and coordination supramolecular network provided a facile means for the modulation of luminescent and mechanical properties of *** strategies and results reported should be beneficial to molecular assemblies,dynamic polymers,biological delivery,and intelligent materials.

关键词： Dynamic covalent chemistry Internal protecting group Kinetic stability Imine bond Dynamic polymer

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Local search yields a PTAS for fixed-dimensional k-means problem with penalties

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journal of the Operations Research Society of China 2024年第2期12卷 351-362页

作者： Fan Yuan Da-Chuan Xu Dong-lei Du Dong-Mei Zhang Beijing Institute for Scientific and Engineering Computing Beijing University of TechnologyBeijing 100124China Faculty of Management University of New BrunswickFrederictonNB E3B 9Y2Canada School of Computer Science and Technology Shandong Jianzhu UniversityJinan 250101ShandongChina

We study a problem called the k-means problem with penalties(k-MPWP),which is a natural generalization of the typical k-means *** this problem,we have a set D of client points in R^(d),a set F of possible centers in R^(d),and a penalty cost Pj>O for each point j∈*** are also given an integer k which is the size of the center point *** want to find a center point set S■F with size k,choose a penalized subset of clients P■D,and assign every client in D\P to its open *** goal is to minimize the sum of the squared distances between every point in D\P to its assigned centre point and the sum of the penalty costs for all clients in *** using the multi-swap local search technique and under the fixed-dimensional Euclidean space setting,we present a polynomial-time approximation scheme(PTAS)for the k-MPWP.

关键词： Approximation algorithm k-means Local search Penalty

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