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Seismic assessment of RC frames infilled with innovative CFS walls considering seismic orientation effect

Science China(Technological Sciences) 2023年第2期66卷 417-428页

作者： liU pengfei li LuXi School of Civil Engineering Shenyang Jianzhu UniversityShenyang 110168China Guangzhou University-Curtin University Joint Research Centre for Structural Monitoring and Protection Against Multi-Dynamic Hazards School of Civil EngineeringGuangzhou UniversityGuangzhou 510006China

The metal tailings porous concrete cold-formed steel(MCFS)wall is an innovative cold-formed steel(CFS)wall with good thermal and mechanical properties,which has the potential to be widely utilized as the infilled wall(IW).In this paper,the MCFS walls are adopted in the reinforced concrete(RC)frame,and the seismic performance of the building subjected to ground motions with various incidence angles are investigated.Three-dimensional finite element model of the studied building is developed with full consideration of the in-plain(IP)and out-of-plane(OP)behavior of MCFS walls.Incremental dynamic analysis is conducted to obtain the deformation responses of frames and damage ratios of MCFS walls under the combined effect of seismic intensity and orientation.Fragility curves are generated to assess the seismic performance of the building and investigate the effect of ground motion orientation.The results validate the superior performance of infilled MCFS walls,and reveal that the seismic orientation has a considerable impact on the response along each reference axis of the structure.Furthermore,different incidence angles induce up to 10.2%and 14.4%variations in the median Sa(T1)of fragilities for the frames in X and Y axes,and the corresponding change rates in the median Sa(T1)for the walls are 13.5%and 15.1%,respectively.However,for the overall performance of the building,the seismic orientation effect is less significant.The rates of changes in median Sa(T1)are less than 4%for both frames and MCFS walls.

关键词： metal tailings porous concrete CFS wall RC frame in-plane out-of-plane orientation effect

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Regio-and Diasteroselective C-Silylation of Enolate Enabled by a β-Boronyl Group

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Chinese Journal of Chemistry 2022年第9期40卷 1028-1032页

作者： Yu liu Miao Zhan pengfei li National Drug Clinical Trial Institution GCP Office The First Affiliated Hospital of Xi'an Jiaotong UniversityXi'anShaanxi 710061China Institute of Medical Research Northwestern Polytechnical UniversityXi'anShaanxi 710072China Frontier Institute of Science and Technology Xi'an Jiaotong University99 Yanxiang RoadXi'anShaanxi 710054China

Silyl enol ethers are often obtained when the lithium enolates are trapped with chlorosilanes.Herein,we report a general method for the regio-and diasteroselective C-silylation of enolate enabled by theβ-boronyl group.The formation of five-membered chelation intermediate is key to the C-selective silylation and anti-selectivity.The operationally simple protocol provides a general and predictable access to theα-silylated esters.The synthetic versatility of the boron-silicon bifunctional products was demonstrated by down-stream transformations.

关键词： Silylation Boron Diastereoselectivity Enolate Nucleophilic substitution

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暗环境下利用改良聚光灯测距的方法

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计算机工程与应用 2016年第7期52卷 155-159页

作者：李洪歧鲁怀伟李鹏飞兰州交通大学电子与信息工程学院兰州730070 兰州交通大学数理学院兰州730070 兰州交通大学自动化与电气工程学院兰州730070

针对传统的基于激光和传感器测距方式复杂和昂贵的缺点,提出了一种利用改良聚光灯的测距方法。该方法根据暗环境的特点,使用透镜改良聚光灯产生边缘效果好的光斑;变化的阈值实现对图像中的区域分割,利用环形质心接近的方法确定白光照射... 详细信息

针对传统的基于激光和传感器测距方式复杂和昂贵的缺点,提出了一种利用改良聚光灯的测距方法。该方法根据暗环境的特点,使用透镜改良聚光灯产生边缘效果好的光斑;变化的阈值实现对图像中的区域分割,利用环形质心接近的方法确定白光照射的焦点位置,利用三角方法实现测距。经实验验证,该方法区别于使用激光等测距,可以快速地处理复杂背景下的精度要求不高的测距任务,还可以为摄像头提供光源来获取颜色、细节等图像信息。

关键词：测距改良聚光灯结构光三角测距

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A Possible γ-Ray Pulsation from PSR J1740-5340B in the Globular Cluster NGC 6397

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Research in Astronomy and Astrophysics 2024年第1期24卷 285-291页

作者： Jiao Zheng pengfei Zhang li Zhang Department of Astronomy School of Physics and AstronomyKey Laboratory of Astroparticle Physics of Yunnan ProvinceYunnan UniversityKunming 650091China

Recently, a new radio millisecond pulsar(MSP) J1740-5340B, hosted in the globular cluster(GC) NGC 6397,was reported with a 5.78 ms spin period in an eclipsing binary system with a 1.97 days orbital period. Based on a modified radio ephemeris updated by tool tempo2, we analyze the ~15 yr γ-ray data obtained from the Large Area Telescope on board the Fermi Gamma-ray Space Telescope and detect PSR J1740-5340B's γ-ray pulsation at a confidence level of ~4σ with a weighted H-test value of ~26. By performing a phase-resolved analysis, the γ-ray luminosity in on-pulse interval of PSR J1740-5340B is L_(γ)~ 3.8 × 10^(33) erg s^(-1) using NGC 6397's distance of 2.48 kpc. And γ-rays from the on-pulse part of PSR J1740-5340B contribute ~90% of the total observed γ-ray emissions from NGC 6397. No significant γ-ray pulsation of another MSP J1740-5340A in the GC is detected.Considering that the previous four cases of MSPs in GCs, more data in γ-ray, X-ray, and radio are encouraged to finally confirm the γ-ray emissions from MSP J1740-5340B, especially starving for a precise ephemeris.

关键词： gamma-rays:galaxies (stars:)pulsars:individual(PSR J1740-5340B) (Galaxy:)globular clusters:individual(NGC 6397)

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Specialization and Coordination: New Paradigm, Theory, and Path for Regional Development

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China Economist 2024年第1期19卷 76-85页

作者： Lu Ming Xiang Kuanhu LI Pengfei li Jiewei Zhong Yuejun Antai College of Economics&Management Shanghai Jiao Tong UniversityShanghaiChina School of Economics Shanghai UniversityShanghai School of Economics and Management Shanghai Maritime UniversityShanghai Faculty of Economics and Management East China Normal UniversityShanghai

In its new development stage,China seeks to derive new dynamism from reform and opening up at a higher level to boost consumption and services.This process coincides with a further differentiation of comparative advantages across regions.Economic activity and population will continue to concentrate in clusters in coastal and central cities amid a continuous outflow of population from remote areas.Development expansion from coastal to interior regions and from central cities to the periphery will promote a new regional development paradigm of“dual centers and periphery”.Therefore,China’s regional development strategy should follow the new theory of seeking relative equilibrium amid development,identify regions of population inflow and outflow,and explore a new development path of regional specialization and coordination.By deepening market reforms and increasing central government coordination,the country is poised to improve the spatial allocation of resources and unleash institutional dividends in the process of developing a unified national market.

关键词： Regional development “dual centers-periphery” comparative advantage population migration

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Predictions of ground surface settlement for shield tunnels in sandy cobble stratum based on stochastic medium theory and empirical formulas

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Underground Space 2023年第4期11卷 189-203页

作者： Fan Wang Xiuli Du pengfei li Key Laboratory of Urban Security and Disaster Engineering Ministry of EducationBeijing University of TechnologyBeijing 100124China

This paper focuses on the prediction of ground surface settlement induced by shield tunnelling in sandy cobble stratum.Based on the stochastic medium theory,an analytical solution to predict the surface settlement is developed considering the difference between soil and tunnel volume loss.Then,the effects of tunnel geometries,influence angle and volume loss on the characteristics of surface settlement are discussed.Through back analysis,a total of 103 groups of field monitoring data of surface settlement induced by shield tunnelling in sandy cobble stratum are examined to investigate the statistical characteristics of the maximum settlement,settlement trough width and volume loss.An empirical prediction is presented based on the results of back analysis.Finally,the analytical solution and empirical expression are validated by the comparisons with the results of model tests and field monitoring.Results show that the soil at ground surface has an overall dilative response for most of the shield tunnelling in sandy cobble stratum.In addition,the developed analytical solution is applicable and reasonable for surface settlement prediction.Meanwhile,the proposed empirical formula also shows good per-formance in some cases,providing an approach or a reference for engineering designers to preliminarily evaluate the surface settlement.

关键词： Shield tunnelling Sandy cobble stratum Ground surface settlement Stochastic medium theory Empirical formulas

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Review of Research Advances in CFD Techniques for the Simulation of Urban Wind Environments

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Fluid Dynamics & Materials Processing 2022年第2期18卷 449-462页

作者： pengfei Ju Mingrui li Jingying Wang Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control School of Mechanical EngineeringTianjin University of TechnologyTianjin300384China National Demonstration Center for Experimental Mechanical and Electrical Engineering Education(Tianjin University of Technology) Tianjin300384China School of Energy and Power Engineering Shandong UniversityJinan250061China Shandong Engineering Laboratory for High-Efficiency Energy Conservation and Energy Storage Technology&Equipment Shandong UniversityJinan250061China

Computational fluid dynamics(CFD)has become the main method for the prediction of the properties of the external wind environment in cities and other urban contexts.A review is presented of the existing literature in terms of boundary conditions,building models,computational domains,computational grids,and turbulence models.Some specific issues,such as the accuracy/computational cost ratio and the exploitation of existing empirical correlations,are also examined.

关键词： Computational fluid dynamics wind environment pre-processing settings

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Bearing capacity and failure behavior of disconnectable coupling joint with double row wedges(DCJD)used in the prestressed internal bracing

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Underground Space 2022年第4期7卷 498-513页

作者： Mingju Zhang Zhitian Xie pengfei li Key Laboratory of Urban Security and Disaster Engineering Ministry of EducationBeijing University of TechnologyBeijing 100124China

A disconnectable coupling joint with double row wedges(DCJD)is a crucial component of the prestressed internal bracing in subway foundation pits.However,only a few studies have been conducted on the bearing capacity of the joints;moreover,the yield load and compression stiffness of DCJDs are typically determined from experience.The aim of this study was to quantitatively determine the bearing capacity and propose accurate formulas for calculating the yield load and compression stiffness of DCJDs.Hence,a DCJD was selected from a foundation pit in Beijing,China,and loading experiments were conducted under axial force.Load–displacement and load–strain curves were obtained,and the failure modes of the joint were analyzed.The experimental results were verified through several finite element models.Subsequently,parametric analyses were performed to investigate the effects of the dimensions of the key position on the DCJD’s bearing capacities.Moreover,regression analysis was used to obtain the formulae for estimating the initial compression stiffness and yield load of the DCJD.Finally,the fitting formulae results were compared with the numerical and experimental results.The comparisons showed that the fitting formulae were highly accurate in estimating the bearing capacity of the DCJD.

关键词： Deep foundation pit Disconnectable coupling joints Loading experiments Parametric study Formulae fitting

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Optimizing environmental insulation thickness of buildings with CHP-based district heating system based on amount of energy and energy grade

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Frontiers in Energy 2022年第4期16卷 613-628页

作者： Yumei ZHANG pengfei JIE Chunhua liU Jing li School of Mechanical Engineering Beijing Institute of Petrochemical TechnologyBeijing 102617China Engineering and Technology R&D Center of Clean Air Conditioning in Colleges of Shandong Shandong Huayu University of TechnologyDezhou 253000China China Environmental Resources Technology Co. LtdBeijing 100012China

The increase of insulation thickness(IT)results in the decrease of the heat demand and heat medium temperature.A mathematical model on the optimum environmental insulation thickness(OEIT)for minimizing the annual total environmental impact was established based on the amount of energy and energy grade reduction.Besides,a case study was conducted based on a residential community with a combined heat and power(CHP)-based district heating system(DHS)in Tianjin,China.Moreover,the effect of IT on heat demand,heat medium temperature,exhaust heat,extracted heat,coal consumption,carbon dioxide(CO_(2))emissions and sulfur dioxide(SO_(2))emissions as well as the effect of three types of insulation materials(i.e.,expanded polystyrene,rock wool and glass wool)on the OEIT and minimum annual total environmental impact were studied.The results reveal that the optimization model can be used to determine the OEIT.When the OEIT of expanded polystyrene,rock wool and glass wool is used,the annual total environmental impact can be reduced by 84.563%,83.211%,and 86.104%,respectively.It can be found that glass wool is more beneficial to the environment compared with expanded polystyrene and rock wool.

关键词： optimum environmental insulation thickness heat medium temperature energy grade extracted heat exhaust heat

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Access to Stereodefined Multifunctionalizedβ,γ-Unsaturated Ketones via Chemo,Regio-and Diastereoselective Copper-Catalyzed Diborylation of Cross-Conjugated Enynones

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Chinese Journal of Chemistry 2021年第3期39卷 590-596页

作者： Shuai Zhang Xinhua Duan pengfei li Frontier Institute of Science and Technology Xi'an Jiaotong UniversityXi'anShaanxi 710054China School of Chemistry Xi'an Jiaotong UniversityXi'anShaanxi 710049China State Key Laboratory of Elemento-Organic Chemistry Nankai UniversityTianjin 300071China Xi'an Key Laboratory of Sustainable Energy Materials Chemistry Xi'an Jiaotong UniversityXi'anShaanxi 710049China

Main observation and conclusion Stereodefinedβ,γ-unsaturated carbony|compounds are important yet synthetically challenging units in natural products and drugs.Disclosed herein is a mild,rapid copper-catalyzed diborylation reaction of cross-conjugated enynones as a step-economic and modular approach to stereodefined multifunctionalizedβ,γ-unsaturated ketones by fine control of chemo-,regio-,Z/E and diastereoselectivity.The substrate scope was examined and a possible catalytic cycle was proposed to explain the multifaceted selectivity.

关键词： Stereoselectivity β,γ-Unsaturated ketones Copper catalysis Borylation Cross-conjugated enynones

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