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Differences in Precipitation and Related Wind Dynamics and Moisture and Heat Features in Separate Areas of the South China Sea before and after Summer Monsoon Onset

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Advances in Atmospheric Sciences 2024年第8期41卷 1643-1660页

作者： Chunyan ZHANG Donghai WANG Kaifeng ZHANG Wanwen HE yanping zheng Yan XU Guangdong Meteorological Data Center Guangdong Meteorological BureauGuangzhou 510640China School of Atmospheric Sciences Sun Yat-sen UniversityGuangdong Province Key Laboratory for Climate Change and Natural Disaster StudiesKey Laboratory of Tropical Atmosphere-Ocean SystemMinistry of EducationZhuhai 519082China Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai) Zhuhai 519082China National Observation and Research Station of Coastal Ecological Environments in Macao Macao Environmental Research InstituteMacao University of Science and TechnologyMacao SAR 999078China Foshan Meteorological Service Foshan 528000China Ningjiang District Meteorological Bureau Songyuan 138000China

Using surface and balloon-sounding measurements, satellite retrievals, and ERA5 reanalysis during 2011–20, this study compares the precipitation and related wind dynamics, moisture and heat features in different areas of the South China Sea(SCS) before and after SCS summer monsoon onset(SCSSMO). The rainy sea around Dongsha(hereafter simply referred to as Dongsha) near the north coast, and the rainless sea around Xisha(hereafter simply referred to as Xisha) in the western SCS, are selected as two typical research subregions. It is found that Dongsha, rather than Xisha, has an earlier and greater increase in precipitation after SCSSMO under the combined effect of strong low-level southwesterly winds, coastal terrain blocking and lifting, and northern cold air. When the 950-h Pa southwesterly winds enhance and advance northward, accompanied by strengthened moisture flux, there is a strong convergence of wind and moisture in Dongsha due to a sudden deceleration and rear-end collision of wind by coastal terrain blocking. Moist and warm advection over Dongsha enhances early and deepens up to 200 h Pa in association with the strengthened upward motion after SCSSMO, thereby providing ample moisture and heat to form strong precipitation. However, when the 950-h Pa southwesterly winds weaken and retreat southward, Xisha is located in a wind-break area where strong convergence and upward motion centers move in. The vertical moistening and heating by advection in Xisha enhance later and appear far weaker compared to that in Dongsha, consistent with later and weaker precipitation.

关键词： Dongsha Xisha South China Sea summer monsoon onset precipitation wind dynamics moisture heat

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Seismic response of a mid-story isolated structure considering SSI in mountainous areas under long-period earthquakes

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Earthquake Engineering and Engineering Vibration 2024年第1期23卷 151-161页

作者： Wan Feng Qin Shengwu Liu Dewen Zhao Tiange zheng yanping Shan Hang Li Zhiang Peng Fusong Xu Jingran Lei Min College of Construction Engineering Jilin UniversityChangchun 130015China College of Civil Engineering Southwest Forestry UniversityKunming 650024China College of civil engineering Southwest Jiaotong UniversityChengdu 610031China

At present,there is not much research on mid-story isolated structures in mountainous *** this study,a model of a mid-story isolated structure considering soil-structure interaction(SSI)in mountainous areas is established along with a model that does not consider *** long-period earthquake waves and two ordinary earthquake waves are selected as inputs for the dynamic time history analysis of the *** results show that the seismic response of a mid-story isolated structure considering SSI in mountainous areas can be amplified when compared with a structure that does not consider *** structure response under long-period earthquakes is larger than that of ordinary *** structure response under far-field harmonic-like earthquakes is larger than that of near-fault pulse-type *** structure response under near-fault pulse-type earthquakes is larger than that of far-field non-harmonic *** subjected to long-period earthquakes,the displacement of the isolated bearings exceeded the limit value,which led to instability and overturning of the *** structure with dampers in the isolated story could adequately control the nonlinear response of the structure,effectively reduce the displacement of the isolated bearings,and provide a convenient,efficient and economic method not only for new construction but also to retrofit existing structures.

关键词： SSI in mountainous areas long-period earthquakes mid-story isolated structure structural dynamic analysis

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Dynamic tracking of exsolved PdPt alloy/perovskite catalyst for efficient lean methane oxidation

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Chinese Chemical Letters 2024年第4期35卷 170-175页

作者： Yanling Yang Zhenfa Ding Huimin Wang Jianhui Li yanping zheng Hongquan Guo Li Zhang Bing Yang Qingqing Gu Haifeng Xiong Yifei Sun College of Energy Xiamen UniversityXiamen 361005China School of Environment and Civil Engineering Dongguan University of TechnologyDongguan 523808China Department of Chemistry College of Chemistry and Chemical EngineeringXiamen UniversityXiamen 361005China State Key Laboratory of Physical Chemistry of Solid Surfaces College of Chemistry and Chemical EngineeringXiamen UniversityXiamen 361005China CAS Key Laboratory of Science and Technology on Applied Catalysis Dalian Institute of Chemical PhysicsChinese Academy of SciencesDalian 116023China Innovation Laboratory for Sciences and Technologies of Energy Materials of Fujian Province(IKKEM) Xiamen 361102China

Supported Pd based catalysts are considered as the efficient candidates for low-carbon alkane oxidation for their outstanding capability to break C-H bond. Whereas, the irreversible deactivation of Pd based catalysts was still frequently observed. Herein, we reinforced the extruded Pd nanoparticles with quantitive Pt to assemble the evenly distributed Pd Pt nanoalloy onto ferrite perovskite(Pd Pt-LCF) matrix with strengthened robustness of metal/oxide support interface. We further co-achieved the enhanced performance, anti-overoxidation as well as resistance of vapor-poisoning in durability measurement. The operando X-ray photoelectron spectroscopy(O-XPS) combined with various morphology characterizations confirms that the accumulation of surface deep-oxidation species of Pd^(4+) is the culprit for fast activity loss in exsolved Pd system, especially at high temperature of 400 ℃. Conversely, it could be completely suppressed by in-situ alloying Pd with equal amount of Pt, which helps maintain the metastable Pd^(2+)/Pd shell and metallic solid-solution core structure. The density function theory(DFT) calculations further buttress that the dissociation of C–H was facilitated on alloy/perovskite interface which is, on the contrary, resistant toward O–H bond cleavage, as compared to Pd/perovskite. Our work suggests that the modification of exsolved metal/oxide catalytic interface could further enrich the toolkit of heterogeneous catalyst design.

关键词： Exsolution PdPt alloy Operando characterization Methane conversion Deep-oxidation

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Rh/Al_(2)O_(3)催化剂在丙烷脱氢反应中的表面变化

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Chinese Journal of Catalysis 2024年第7期62卷 145-155页

作者：李书毅穆长乐何念秋徐杰郑燕萍陈明树厦门大学化学化工学院固体表面物理化学国家重点实验室福建厦门361005

丙烯是一种重要的化工原料,需求量较大且逐年增加.丙烷脱氢(PDH)是一种高效的生产丙烯过程,正逐步取代石脑油裂解成为重要的丙烯生产工艺.开发高效且稳定的PDH催化剂将对PDH工业发展起到积极的推动作用.Rh因其较好的C-H键活化能力,展现... 详细信息

丙烯是一种重要的化工原料,需求量较大且逐年增加.丙烷脱氢(PDH)是一种高效的生产丙烯过程,正逐步取代石脑油裂解成为重要的丙烯生产工艺.开发高效且稳定的PDH催化剂将对PDH工业发展起到积极的推动作用.Rh因其较好的C-H键活化能力,展现出作为PDH催化剂的巨大潜力,但关于Rh应用于PDH的报道较少.明确Rh物种尺寸对PDH产物选择性的影响,对后续设计高效且稳定的Rh基PDH催化剂至关重要.多相催化反应主要发生在催化剂的表面,因此,催化剂的表面状态对其催化性能具有重要的影响.在催化反应过程中,一些催化剂的表面状态会发生显著变化,这些变化会导致活性、产物选择性明显变化.通过采用(准)原位表面研究手段,能够清晰地了解催化剂在反应过程中的表面变化,这对于建立催化剂结构与反应性能之间的构效关系具有非常重要的意义.本文通过沉积-沉淀法制备了不同负载量的Rh/Al_(2)O_(3)催化剂,旨在探究Rh物种尺寸对PDH产物选择性的影响.球差电镜(AC-HAADF-STEM)观察显示,Rh物种以团簇和单原子的形式共存于Al_(2)O_(3)载体上.进一步通过准原位X射线光电子能谱(XPS)证实了不同化学态的Rh物种.通过固定床反应器对Rh/Al_(2)O_(3)催化剂的PDH性能进行测试,结果表明,催化剂在反应初始阶段需要经历诱导期.在此期间,甲烷的选择性显著降低,而丙烯的选择性显著升高,同时,丙烷的转化率显著降低.碳平衡计算表明,诱导期内产生了大量积碳.采用准原位XPS、低能离子散射谱(LEIS)和CO吸附红外光谱(CO-FTIR)研究了Rh/Al_(2)O_(3)催化剂在诱导期的表面变化.结果表明,在反应初始阶段,催化剂表面有大量积碳产生,这些积碳主要聚集在Rh物种表面,覆盖了Rh团簇,而Rh单原子则保持暴露状态,并作为PDH反应的活性中心.AC-HAADF-STEM结果表明,PDH反应4 h后,仍有Rh单原子存在于催化剂表面.结合Rh/Al_(2)O_(3)催化剂的PDH性能和准原位表征结果认为,丙烷在Rh团簇表面发生C-C键断裂反应,生成甲烷和积碳.积碳对Rh团簇的覆盖抑制了丙烷裂解反应,导致甲烷的选择性在诱导期显著降低;而Rh单原子则仍然暴露,具有催化PDH反应活性,并且是高选择性地生成丙烯的位点.该选择性的差异由丙烯在不同尺寸Rh物种上的吸附方式不同引起的,在Rh团簇表面以di-σ键吸附方式为主,吸附强度较强,丙烯不易脱附,并进一步发生裂解产生甲烷和积碳;而在Rh单原子上,丙烯以π键吸附方式存在,吸附强度较弱,不易发生副反应.对反应后的Rh/Al_(2)O_(3)催化剂进行分析,发现积碳主要为碳氢化合物和石墨碳,且随着反应进行,积碳从Rh团簇表面向Al_(2)O_(3)载体上转移.综上所述,本文通过使用准原位XPS,LEIS和CO-FTIR等技术探究了Rh/Al_(2)O_(3)催化剂在PDH反应中的表面变化,揭示了Rh物种尺寸对PDH产物选择性的影响.结果表明,Rh单原子对丙烯选择性有利,而在Rh团簇表面PDH产物主要为甲烷并产生积碳,同时积碳导致了催化剂在反应初始阶段的快速失活.本工作为后续高效Rh基PDH催化剂的设计提供参考.

关键词：丙烷脱氢铑积碳单原子准原位谱学表面变化

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一种复合电源纯电动公交车再生制动控制策略

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重庆理工大学学报（自然科学） 2024年第5期38卷 71-77页

作者：王喆云郑燕萍陆强南京林业大学汽车与交通工程学院南京210037

为了提高纯电动公交车制动能量的回收效率,考虑电机转速特性与电池充电功率的限制,计算电机在约束条件下能提供的最大再生制动力,结合I曲线确定前、后轮制动力分配,以及摩擦制动力与再生制动的分配比例,提出了一种充分利用电机特性的再... 详细信息

为了提高纯电动公交车制动能量的回收效率,考虑电机转速特性与电池充电功率的限制,计算电机在约束条件下能提供的最大再生制动力,结合I曲线确定前、后轮制动力分配,以及摩擦制动力与再生制动的分配比例,提出了一种充分利用电机特性的再生制动控制策略。针对单一动力电池功率密度低、循环寿命短等问题,设计了由动力电池与超级电容组成的复合能源系统,并提出利用实时小波控制策略将需求功率分解成高频成分与低频成分,其中高频功率由超级电容承担,避免动力电池受到冲击,低频功率则由动力电池承担。最后,利用Matlab/Simulink软件建立仿真模型,在中国典型城市循环工况下进行仿真,仿真结果表明:采用动力电池单一能量源时,电池SOC增加了19.03%,制动能量回收率提高了13.10%;采用复合电源时,电池的电流、功率与电压明显减小,波动更加平缓,电池SOC增加了17.51%,制动能量回收率提高了10.24%,可有效提高纯电动公交车的动力电池寿命与整车经济性。

关键词：纯电动公交车复合能源再生制动滑动窗口小波变换

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全球海洋中心城市的湾区实践——以粤港澳大湾区为例

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城市观察 2024年第3期91卷 4-15,158页

作者：王世福郑艳萍刘铮华南理工大学建筑学院华南理工大学亚热带建筑与城市科学全国重点实验室

粤港澳大湾区是加快实施海洋强国战略的重要支点,全球海洋中心城市建设则是进一步推动粤港澳大湾区建设的关键抓手。全球海洋中心城市作为当前海洋城市建设与评价最具影响力的目标对象,需要分别在全球与湾区视角下考察粤港澳大湾区的优... 详细信息

粤港澳大湾区是加快实施海洋强国战略的重要支点,全球海洋中心城市建设则是进一步推动粤港澳大湾区建设的关键抓手。全球海洋中心城市作为当前海洋城市建设与评价最具影响力的目标对象,需要分别在全球与湾区视角下考察粤港澳大湾区的优势与挑战。本研究通过解读全球海洋中心城市的概念与内涵,剖析了典型全球海洋中心城市的显著特征,以及与国际一流湾区发展的关系。研究发现,粤港澳大湾区在全球海洋中心城市数量和航运物流方面具有优势,但是在海事技术、竞争力与吸引力等方面面临巨大的竞争挑战。粤港澳大湾区推进全球海洋中心城市建设,着重要加快提升国际航运能力、加强海洋科技创新、参与全球海洋治理、强化海洋战略规划等。

关键词：全球海洋中心城市全球领先海事之都粤港澳大湾区海洋治理海洋强国

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INTEGRAL EQUATION METHOD'S APPLICATION IN HOLE-EDGE STRESS OF COMPOSITE MATERIAL PLATE WITH DIFFERENT SHAPED HOLES

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Chinese Journal of Mechanical Engineering 2008年第6期21卷 115-118页

作者： LI Cheng zheng yanping School of Mechanical Engineering Zhengzhou University Zhengzhou 450001 China

The strength of composite plate with different hole-shapes is always one of the most important but complicated issues in the application of the composite material. The holes will lead to mutations and discontinuity to the structure. So the hole-edge stress concentration is always a serious phenomenon. And the phenomenon makes the structure strength decrease very quickly to form dangerous weak points. Most partial damage begins from these weak points. According to the complex variable functions theory, the accurate boundary condition of composite plate with different hole-shapes is founded by conformal mapping method to settle the boundary condition problem of complex hole-shapes. Composite plate with commonly hole-shapes in engineering is studied by several complex variable stress fimction. The boundary integral equations are founded based on exact boundary conditions. Then the exact hole-edge stress analytic solution of composite plate with rectangle holes and wing manholes is resolved. Both of offset axis loadings and its influences on the stress concentration coefficient of the hole-edge are discussed. And comparisons of different loads along various offset axis on the hole-edge stress distribution of orthotropic plate with rectangle hole or wing manhole are made. It can be concluded that hole-edge with continuous variable curvatures might help to decrease the stress concentration coefficient; and smaller angle of outer load and fiber can decrease the stress peak value.

关键词： Off-axis loads Conformal mapping Aperture question Complex hole-shape Analysis Stress function of multiple complex variables

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SOLUTION OF DIFFERENT HOLES SHAPE BORDERS OF FIBRE REINFORCED COMPOSITE PLATES BY INTEGRAL EQUATIONS

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Chinese Journal of Mechanical Engineering 2007年第5期20卷 23-27页

作者： LI Cheng zheng yanping CHEN Zhongzhong School of Mechanical Engineering Zhengzhou University Zhengzhou 450001 China

Accurate boundary conditions of composite material plates with different holes are founded to settle boundary condition problems of complex holes by conformal mapping method upon the nonhomogeneous anisotropic elastic and complex function theory. And then the two stress functions required were founded on Cauchy integral by boundary conditions. The final stress distributions of opening structure and the analytical solution on composite material plate with rectangle hole and wing manholes were achieved. The influences on hole-edge stress concentration factors are discussed under different loads and fiber direction cases, and then contrast calculates are carried through FEM.

关键词： Fibre reinforced composite Accurate boundary conditions Mapping functions Complex hole shape Integral equations

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Tensile properties analysis of CFRP-titanium plate multi-bolt hybrid joints

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Chinese Journal of Aeronautics 2022年第3期35卷 464-474页

作者： yanping zheng Chaoyu ZHANG Ying TIE Xu WANG Mingkun LI School of Mechanical and Power Engineering Zhengzhou UniversityZhengzhou 450001China

Hybrid joints have better tensile properties than pure bonded and bolted bolts,and are increasingly used in the aerospace *** tests are carried out for the Hybrid Bonded/Bolted(HBB)joints of Carbon Fiber Reinforced Polymer(CFRP)laminate and titanium alloy plate under different bolt numbers,and the corresponding load–displacement curves are *** the same time,based on Continuum Damage Mechanics(CDM)theory,which is derived from 3D Hashin failure criteria,and a Cohesive Zone Model(CZM),the tensile strength prediction model of the composite laminate-titanium alloy plate multi-bolted HBB joint was established,and the numerical simulation results were in good agreement with the experimental height,which validate the feasibility of the *** difference in the bearing capacity of HBB joints under different numbers of bolts is compared and *** this basis,the influence of inter-bolt distance on the tensile properties of the HBB joints is *** results show that the double-nail HBB joints can effectively improve the end warpage and low bearing capacity of the single-nail HBB *** tensile failure load of the double-nail HBB joints under the standard lap width(30 mm)is 82.6%higher than that of the single nail,the tensile failure load of the three-bolt HBB joints is 34.1%higher than that of the double *** the three-bolt HBB joint,the joint strength is controlled by the adhesive and the external bolt,while the internal bolt is redundant,the hybrid joint can be simplified by reducing the middle *** inter-bolt distance has a great influence on the failure load of the hybrid *** the inter-bolt distance can effectively improve the bearing capacity of the structure.

关键词： CFRP laminate Finite element model Hybrid(bonded/bolted)joint Multi-bolt Tensile properties

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用于电子芯片的热电制冷器性能分析与评估

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低温与超导 2024年第2期52卷 86-96页

作者：徐志男赵华东李成张景双郑艳萍郑州大学机械与动力工程学院郑州450001

为了探究热电制冷器(Thermoelectric Cooler,TEC)对电子芯片的散热效果以及自身性能的发挥,建立了TEC风冷散热模型进行有限元分析。通过对不同热源表面温度、TEC冷热端温差、制冷速率等关键参数的研究分析,得到了电流、热源表面温度和... 详细信息

为了探究热电制冷器(Thermoelectric Cooler,TEC)对电子芯片的散热效果以及自身性能的发挥,建立了TEC风冷散热模型进行有限元分析。通过对不同热源表面温度、TEC冷热端温差、制冷速率等关键参数的研究分析,得到了电流、热源表面温度和外界散热条件对TEC散热性能的影响规律,通过有限元分析评估了不同条件下TEC的有效工况以及适用范围。结果表明:在一定的环境温度和散热条件下存在最佳电流,使得TEC的适用工况范围最大;适用范围随着环境温度的升高而有所扩大。

关键词：热电制冷器有限元分析有效工况

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