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Catalytically active interfaces in titania nanorod-supported copper catalysts for CO oxidation

Nano Research 2020年第2期13卷 533-542页

作者： Wasim U.Khan Season S.Chen Daniel C.W.Tsang Wey yang Teoh Xijun Hu frank l.y.lam Alex C.K.yip Department of Chemical and Process Engineering The University of Canterbury Christchurch 8041New Zealand Department of Civil and Environmental Engineering.The Hong Kong Polytechnic University Hong Kong.China School of Chemical Engineering The University of New South WalesSydneyNSW 2052Australia Department of Chemical and Biological Engineering The Hong Kong University of Science and TechnologyHong KongChina

One-dimensional titanium dioxide nanorod(TNR)-supported Cu catalysts(2.5 wt.%-12.5 wt.%)were synthesized using deposition-precipitation.X-ray photoelectron spectroscopy,temperature programmed reduction and CO chemisorption measurements showed that Cu doping over TNR offered metal-support interactions and interfacial active sites that had a profound impact on the catalytic *** role of the Cu-TNR interface was investigated by comparing the catalytic activity of Cu-TNR catalysts with that of pure CuO nanoparticles in CO *** presence of highly dispersed copper species,a high number of interfacial active sites,CO adsorption capacity and surface/lattice oxygen were found to be responsible for the excellent activity of 7.5CU-TNR(ie,Cu loading of 7.5 wt.%on TNR).Moreover,the Cu-TNR catalysts followed the langmuir-Hinshelwood reaction mechanism with 7.5CU-TNR,exhibiting an apparent activation energy of 44.7 kJ/*** TNR-supported Cu catalyst gave the highest interfacial catalytic activity in medium-temperature CO oxidation(120-240℃)compared to other commonly used supports,including titanium dioxide nanoparticles(TiO2-P25),silica(SiO2)and alumina(Al20g)in which copper species were nonhomogeneously *** study confirms that medium-temperature CO oxidation is highly sensitive to the morphology and structure of the supporting material.

关键词： supported catalysts nanorod oxygen species interfacial active sites CO oxidation

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load-sharing mechanism in timber-steel hybrid shear wall systems

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Frontiers of Structural and Civil Engineering 2015年第2期9卷 203-214页

作者： Zheng lI Minjuan HE frank lam Minghao lI Department of Structural Engineering Tongji University Shanghai 200092 China Department of Wood Science University of British Columbia Vancouver V6T 1Z4 Canada Department of Civil & Natural Resources Engineering University of Canterbury Christchurch New Zealand

The lateral performance of timber-steel hybrid shear wall systems with regard to the interaction between the steel frame and the infill wood shear wall was investigated in this paper. A numerical model for the timber-steel hybrid shear wall system was developed and verified against test results. Design parameters, such as the lateral infill-to-frame stiffness ratio and the arrangements of wood-steel bolted connections were studied using the numerical model. Some design recommendations were also proposed based on the parametric analysis. In the hybrid shear wall system, the infill wood wall was found to resist a major part of the lateral load within relatively small wall drifts, and then the steel frame provided more lateral resistance. Under seismic loads, the infill wood wall could significantly reduce the inter-story drift of the hybrid system, and a complementary effect between the infill wood wall and the steel frame was observed through different lateral load resisting mechanisms, which provided robustness to the hybrid shear wall systems.

关键词： timer-steel hybrid shear wall load sharing mechanism seismic performance parametric analysis

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Mechanism of forming an ink-bottle-like pore structure based on SBA-15 by a novel MOCVD technique

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Chinese Science Bulletin 2010年第4期55卷 446-451页

作者： ZHANG ying frank leung-yUK lam yAN ZiFeng HU XiJun School of Chemistry & Chemical Engineering China University of Petroleum Dongying 257061 China Department of Chemical Engineering Hong Kong University of Science and Technology Clear Water Bay Kowloon Hong Kong China

Metallorganic chemical vapor deposition is used as a novel simple pore tailoring method to fine-tune the pore opening size of SBA-15 materials without significant loss in pore volume and surface area. By using acetylene as carbon source and copper (II) acetylacetonate as precursor, the poremouth of SBA-15 is effectively reduced from 5.78 nm to 3.67 nm while maintaining the pore body at 5.78 nm. The effect of four pore modification factors-the ratio of acetylene/nitrogen, the feeding time of carbon precursor, the ratio of SBA-C/Cu(acac)2 and the cycles of MOCVD on the final pore structure of the SBA-15/carbon/copper composite is studied. The morphology and microstructure of the resulting product SBA-C-Cu are characterized by XRD patterns, TEM images and EDS analysis. The XRD and TEM reveal that the SBA-C-Cu composite is highly hexagonally ordered and has similar particle morphology as the original SBA-15.

关键词：金属有机化学气相沉积化学气相沉积技术 SBA 分子筛孔结构铜复合材料化学气相沉积法透射电子显微镜

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Fabrication of copper nanorods by low-temperature metal organic chemical vapor deposition

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Chinese Science Bulletin 2006年第21期51卷 2662-2668页

作者： ZHANG ying frank leung-yuk lam HU Xijun yAN Zifeng State Key laboratory for Heavy Oil Processing Key Laboratory of Catalysis CNPC University of Petroleum Dongying 257061 China Department of chemical Engineering The Hong Kong University of Science and Technology JiuLong Hong Kong China

Copper nanorods have been synthe-sized in mesoporous SBA-15 by a low-temperature metal organic chemical vapor deposition (MOCVD) employing copper (II) acetylacetonate, Cu(acac)2, and hydrogen as a precursor and reactant gas, re- spectively. The hydrogen plays an important role in chemical reduction of oganometallic precursor which enhances mass transfer in the interior of the SBA-15 porous substrate. Such copper nanostructures are of great potentials in the semiconductor due to their unusual optical, magnetic and electronic properties. In addition, it has been found that chemically modi- fying the substrate surface by carbon deposition is crucial to such synthesis of copper nanostructures in the interior of the SBA-15, which is able to change the surface properties of SBA-15 from hydrophilic to hydrophobic to promote the adsorption of organic cupric precursor. It has also been found that the copper nanoparticles deposited on the external sur- face are almost eliminated and the copper nanorods are more distinct while the product was treated with ammonia. This approach could be achieved under a mild condition: a low temperature (400℃) and vac-uum (2 kPa) which is extremely milder than the con- ventional method. It actually sounds as a foundation which is the first time to synthesize a copper nanorod at a mild condition of a low reaction temperature and pressure.

关键词：化学蒸气沉积法铜有机金属分解低温 MOCVD

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Standards and methods for dent assessment and failure prediction of pipelines:A critical review

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Petroleum Science 2022年第6期19卷 3029-3045页

作者： Jian Zhao yun-Rong lv y.frank Cheng Dept.of Mechanical&Manufacturing Engineering University of CalgaryAlbertaT2N 1N4Canada Guangdong Provincial Engineering Technology Research Center of Petrochemical Corrosion and Safety Guangdong University of Petrochemical TechnologyMaomingGuangdongChina

Dent,a common mechanical damage on pipelines,is associated with a significant local plastic *** can cause pipeline failures,especially when they are combined with other types of defects such as gouges,fatigue,corrosion,and *** this work,a systematic review of various assessment methods and standards for pipeline dents,including the combination of a dent with other defects,is ***,the methods available today are not sufficiently accurate and reliable to assess pipeline dents,especially the dent-defect *** plain dents on pipelines,both the depthbased criterion and the strain-based criterion are commonly used in *** main problems include inaccuracy and *** a dent combined with other defects,the existing assessment techniques are not mature enough to give reliable *** experimental testing and numerical modeling through finite element(FE)analysis are capable of investigating the influence of dents and dent-defect combinations on burst failure pressure of the pipelines,although an approximation to the reality is still the main difficulty existing in the experimental testing and FE ***,relevant studies on assessment techniques for plain dents,a dent with fatigue and a dent with a single gouge have been common in *** combinations of a dent with corrosion or cracks have been rarely assessed due to complicated mechanisms involving a multi-physics coupling *** of novel assessment methods by integrating mechanical stress and strain,electrochemical reactions and steel metallurgy will be a key topic to accurately assess the dent-defect combinations for improved pipeline integrity.

关键词： Dents Pipelines Assessment techniques Burst failure pressure Dent-defect combinations

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Guaranteed Cost Attitude Tracking Control for Uncertain Quadrotor Unmanned Aerial Vehicle Under Safety Constraints

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IEEE/CAA Journal of Automatica Sinica 2024年第6期11卷 1447-1457页

作者： Qian Ma Peng Jin frank l.lewis School of Automation Nanjing University of Science and TechnologyNanjing 210094China UTA Research Institute University of Texas at ArlingtonFort WorthTexas 76118 USA IEEE

In this paper,guaranteed cost attitude tracking con-trol for uncertain quadrotor unmanned aerial vehicle(QUAV)under safety constraints is ***,an augmented system is constructed by the tracking error system and reference *** transformation aims to convert the tracking control prob-lem into a stabilization control ***,control barrier function and disturbance attenuation function are designed to characterize the violations of safety constraints and tolerance of uncertain disturbances,and they are incorporated into the reward function as penalty *** on the modified reward function,the problem is simplified as the optimal regulation problem of the nominal augmented system,and a new Hamilton-Jacobi-Bellman equation is ***,critic-only rein-forcement learning algorithm with a concurrent learning tech-nique is employed to solve the Hamilton-Jacobi-Bellman equa-tion and obtain the optimal *** proposed algorithm can not only ensure the reward function within an upper bound in the presence of uncertain disturbances,but also enforce safety *** performance of the algorithm is evaluated by the numerical simulation.

关键词： Attitude tracking control quadrotor unmanned aerial vehicle(QUAV) reinforcement learning safety constraints uncertain disturbances.

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A first assessment of Galapagos basidiolichens

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Fungal Diversity 2012年第1期52卷 225-244页

作者： Alba yánez Manuela Dal-Forno frank Bungartz Robert lücking James D.lawrey Biodiversity Assessment Charles Darwin Foundation(AISBL)Puerto AyoraSanta CruzGalapagosEcuador Universidad Central del Ecuador QuitoEcuador Department of Environmental Science and Policy George Mason UniversityFairfaxVA 22030-4444USA Botany The Field Museum1400 South Lake Shore DriveChicagoIL 60605-2496USA

As part of an ongoing comprehensive inventory of Galapagos lichens,a first assessment of the morphology and anatomy of basidiolichens from the archipelago is presented *** is the basis for further studies of the taxonomy,ecology and biogeography of this poorly known group of *** genera,all in Hygrophoraceae,can be distinguished:Acantholichen,Cora,Cyphellostereum and *** Acantholichen and Cora are characterized by chroococcoid cyanobionts and a heteromerous thallus with a distinct upper cortex and photobiont *** monotypic Acantholichen pannarioides is entirely composed of small,branched,inflated squamules that appear densely pruinose because their cortical hyphae bear characteristically swollen,densely spinose end cells(acanthohyphidia);this species has never been observed *** common Cora glabrata is foliose,forming large,radially zonate,conch-like,often tiled thalli,when fertile with circular lines of basidiocarps on its lower *** is distinguished by filamentous cyanobionts and distinctly filamentous thalli that are homomereous(i.e.,not distinctly layered);all species of Dictyonema *** trichomes(filamentose cyanobacterial photobionts)closely enveloped by fungal cells of a jigsaw *** *** thallus filaments(i.e.,individual fibrils)aggregate to form shelf-like structures similar in appearance to polyporoid bracket fungi;basidiocarps develop in irregular patches on the lower side of these *** contrast,fibrils of *** grow encrusting their substrate with irregularly to suberect trichomes,occasionally bearing basidiocarps dispersed across the *** other species in Galapagos show adpressed growth form and are described here as new:Dictyonema pectinatum,which is characterized by large parallel fibrils with paler,papillate tips,and ***,characterized by thin trichomes of more squarrish elongate *** genus Cyphellostereum is represented by two species:the newly describ

关键词： Census of Galapagos Biodiversity Galapagos lichen Inventory Acantholichen Cora Cyphellostereum Dictyonema

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Modeling and analysis of a catastrophic oil spill and vapor cloud explosion in a confined space upon oil pipeline leaking

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Petroleum Science 2020年第2期17卷 556-566页

作者： Shengzhu Zhang Xu Wang y.frank Cheng Jian Shuai China Academy of Safety Science and Technology Beijing 100012China Department of Mechanical Engineering University of CalgaryCalgaryAB T2N 1N4Canada College of Safety and Ocean Engineering China University of Petroleum(Beijing)Beijing 102249China

Oil spill-induced vapor cloud explosions in a confined space can cause catastrophic *** this work,investigation was conducted on the catastrophic pipeline leak,oil spill,and the resulting vapor cloud explosion accident occurring in China in 2013 by modeling analysis,field surveys,and numerical *** total amount of the spilled oil was up to2044.4 m3 due to improper *** long residence time of the oil remaining in a confined space permitted the formation of explosive mixtures and caused the vapor cloud explosion.A numerical model was developed to estimate the consequence of the explosion based on volatilization testing *** results show that the death-leading zone and the glass-breaking zone could be 18 m and 92 m,respectively,which are consistent with the field *** severity of the explosion is related to the amount of the oil spill,properties of oil,and volatilization *** is recommended that a comprehensive risk assessment be conducted to analyze the possible consequences upon oil spilling into a confined *** collection and ventilation measures should be taken immediately after the spill occurs to reduce the time for oil volatilization and prevent the mixture from reaching its explosive limit.

关键词： Pipeline leaking Oil spill Vapor cloud explosion Confined space Consequence analysis

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Vibration Serviceability of large-Span Steel–Concrete Composite Beam with Precast Hollow Core Slabs Under Walking Impact

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Engineering 2022年第12期19卷 93-104页

作者： Jiepeng liu Shu Huang Jiang li y.frank Chen School of Civil Engineering&Key laboratory of New Technology for Construction of Cities in Mountain Area Ministry of EducationChongqing UniversityChongqing 400045China Central-South Architectural Design Institute Co. Ltd.Wuhan 430071China Department of Civil Engineering The Pennsylvania State UniversityPA 17057USA

A large-span steel–concrete composite beam with precast hollow core slabs(CBHCSs)is a relatively new floor structure that can be applied to various long-span ***,human-induced vibrations may present serviceability issues in such *** alleviate vibrations,both the walking forces excited by humans and the associated floor responses must be *** this study,150 load–time histories of walking,excited by 25 test participants,are obtained using a force measuring *** dynamic loading factors and phase angles in the Fourier series functions for one-step walking are ***,walking tests are performed on seven CBHCS specimens to capture the essential dynamic properties of mode shapes,natural frequencies,damping ratios,and acceleration time *** CBHCS floor system generally exhibits a high frequency(>10 Hz)and low damping(damping ratioy studies using the finite element method are conducted to investigate the vibration performance of the CBHCS floor system,where the floor thickness,steel beam type,contact time,and human weight are ***,analytical expressions derived for the fundamental frequency and peak acceleration agree well with the experimental results and are hence proposed for practical use.

关键词： Composite beam Hollow core slab Walking force Floor vibration Mode shape

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Multi-population particle swarm optimization algorithm for automatic design of steel frames

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Frontiers of Structural and Civil Engineering 2024年第1期18卷 89-103页

作者： Wenchen SHAN Jiepeng lIU yao DING y.frank CHEN Junwen ZHOU Institute of Smart City and Intelligent Transportation Southwest Jiaotong UniversityChengdu 610000China School of Civil Engineering Chongqing UniversityChongqing 400045China Department of Civil Engineering the Pennsylvania State UniversityMiddletownPA 17057USA

Steel structures are widely used;however,their traditional design method is a trial-and-error procedure which is neither efficient nor cost ***,a multi-population particle swarm optimization(MPPSO)algorithm is developed to optimize the weight of steel frames according to standard design *** are made to improve the algorithm performances including the constraint-based strategy,piecewise mean learning strategy and multi-population cooperative *** proposed method is tested against the representative frame taken from American standards and against other steel frames matching Chinese design *** related parameter influences on optimization results are *** the representative frame,MPPSO can achieve greater efficiency through reduction of the number of analyses by more than 65% and can obtain frame with the weight for at least 2.4%lighter.A similar trend can also be observed in cases subjected to Chinese design *** addition,a migration interval of 1 and the number of populations as 5 are recommended to obtain better MPPSO *** purpose of the study is to propose a method with high efficiency and robustness that is not confined to structural scales and design *** aims to provide a reference for automatic structural optimization design problems even with dimensional *** proposed method can be easily generalized to the optimization problem of other structural systems.

关键词： steel frame multi-population particle swarm optimization automatic structural optimization design

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