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Simplified design of nonlinear damper parameters and seismic responses for long-span cable-stayed bridges with nonlinear viscous dampers

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Frontiers of Structural and Civil Engineering 2024年第7期18卷 1103-1116页

作者： Huihui li lifeng li Rui HU Meng YE College of Civil and Transportation Engineering Shenzhen UniversityShenzhen 518060China Guangdong Provincial Key Laboratory of Durability for Marine Civil Engineering Shenzhen UniversityShenzhen 518060China College of Civil Engineering Hunan UniversityChangsha 410082China

Viscous dampers are widely used as passive energy dissipation devices for long-span cable-stayed bridges for mitigation of seismic load-induced ***,complicated finite element(FE)modeling,together with repetitive and computationally intensive nonlinear time-history analyses(NTHAs)are generally required in conventional design *** streamline the preliminary design process,this paper developed a simplified longitudinal double degree of freedom model(DDFM)for single and symmetric twin-tower cable-stayed *** on the proposed simplified longitudinal DDFM,the analytical equations for the relevant mass-and stiffness-related parameters and longitudinal natural frequencies of the structure were derived by using analytical and energy *** of the relationship between the nonlinear viscous damper parameters and the equivalent damping ratio was achieved through the equivalent linearization ***,the analytical equations of longitudinal seismic responses for long-span cable-stayed bridges with nonlinear viscous dampers were *** on the developed simplified DDFM and suggested analytical equations,this paper proposed a simplified calculation framework to achieve a simplified design method of nonlinear viscous damper ***,the effectiveness and applicability of the developed simplified longitudinal DDFM and the proposed calculation framework were further validated through numerical analysis of a practical cable-stayed ***,the results indicated the following.1)For the obtained fundamental period and longitudinal stiffness,the differences between results of the simplified longitudinal DDFM and numerical analysis were only 2.05%and 1.5%,respectively.2)Relative calculation errors of the longitudinal girder-end displacement and bending moment of the bottom tower section of the bridge obtained from the simplified longitudinal DDFM were limited to less than 25%.3)The equivalent damping ratio of nonline

关键词： cable-stayed bridges viscous dampers simplified analytical model equivalent damping ratio seismic mitigation

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Visibility Characteristics over the South China Sea during 1980-2018 Based on Gridded Data Generated by Artificial Neural Network

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Journal of Meteorological Research 2021年第4期35卷 690-700页

作者： lifeng li Yulong SHAN Shijun ZHAO School of Meteorology and Oceanography National University of Defense TechnologyChangsha 430073

This paper generated gridded visibility(Vis)data from 1980 to 2018 over the South China Sea(SCS)based on artificial neural network(ANN),and the accuracy of the generated data was ***,temporal and spatial characteristics of Vis in the area were analyzed based on the generated Vis *** results showed that Vis in the southern SCS was generally better than that in the northern *** the past 39 years,Vis in both spring and winter has improved,especially in winter at a significant increased speed of 0.37 km decade^(-1).However,Vis in both summer and autumn has decreased,especially in summer with an obvious reduction of 0.84 km decade^(-1).Overall,Vis is best in summer and worst in winter,averaging 31.89 km in summer and 20.96 km in winter,which may be related to the difference of climatic conditions and wind speed in different *** the same time,probability of low Vis in spring is significantly higher than that in other seasons,especially in the northwest of Hainan Island and the northwest of Malaysia.

关键词： visibility(Vis) spatiotemporal characteristics South China Sea

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煤矿电网功率因数在线提高方法研究

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煤矿现代化 2025年第1期34卷 97-101页

作者：王海川李蓉李利风山西潞安环保能源开发股份有限公司常村煤矿山西长治046102 潞安职业技术学院山西长治046204

针对如何在线实现煤矿电网功率因数提高问题,本文提出了一种实时在线提高功率因数的方法,首先,通过电网监测系统,建立实时数据库,对电网系统的运行状况进行实时跟踪。其次,在此基础上,对系统进行实时状态估计,纠正系统在线上传数据信息... 详细信息

针对如何在线实现煤矿电网功率因数提高问题,本文提出了一种实时在线提高功率因数的方法,首先,通过电网监测系统,建立实时数据库,对电网系统的运行状况进行实时跟踪。其次,在此基础上,对系统进行实时状态估计,纠正系统在线上传数据信息的错误。最后,对系统进行潮流计算,得到系统功率因数,并对功率因数不合格的节点进行无功补偿,实现功率因数的提高。通过对某一煤矿电网实例进行仿真,验证了本文提出方法的正确性。

关键词：状态估计最小二乘潮流计算无功补偿

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Reliability analysis for mine blast performance based on delay type and firing time

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International Journal of Mining Science and Technology 2018年第2期28卷 195-204页

作者： Silva Jhon li lifeng Gernand Jeremy M. Department of Mining Engineering University of KentuckyLexingtonKY 40506USA The Pennsylvania State University PA 16802USA

Mining blasts may be defined as the use of explosive charges in a controlled manner by following a tightly controlled timing sequence according to an assigned firing order. Changes of timing between charges may result in an altered firing order and failure of the blasting sequence, which can cause high vibration levels, poor fragmentation, and/or an undesirable rock mass movement direction. Despite the importance of timing in determining mine blast results, there exists a lack of methodologies or tools with which to assess performance of a complete blast based on delay type and timing sequence. This document applies reliability engineering principles to evaluate the performance of a mine blast. The analyses are based on test results of the accuracy and precision of electronic and pyrotechnic detonators for typical firing times used in a surface coal mine, but may be applied to a variety of mines and timing scenarios.

关键词： Blast Timing sequence Scatter Reliability Risk analysis Monte Carlo simulation

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The linkage between Midwinter Suppression of the North Pacific Storm Track and Atmospheric Circulation Features in the Northern Hemisphere

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Advances in Atmospheric Sciences 2022年第3期39卷 502-518页

作者： Minghao YANG Chongyin li Xin li Xiong CHEN lifeng li College of Meteorology and Oceanography National University of Defense TechnologyChangsha 410073China State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China

The midwinter suppression(MWS) of the North Pacific storm track(NPST) has been an active research topic for decades. Based on the daily-mean NCEP/NCAR reanalysis from 1948 to 2018, this study investigates the MWS-related atmospheric circulation characteristics in the Northern Hemisphere by regression analysis with respect to a new MWS index, which may shed more light on this difficult issue. The occurrence frequency of the MWS of the upper-tropospheric NPST is more than 0.8 after the mid-1980 s. The MWS is accompanied by significantly positive sea-level pressure anomalies in Eurasia and negative anomalies over the North Pacific, which correspond to a strengthened East Asian winter monsoon. The intensified East Asian trough and atmospheric blocking in the North Pacific as well as the significantly negative low-level air temperature anomalies, lying upstream of the MNPST, are expected to be distinctly associated with the MWS. However, the relationship between the MWS and low-level atmospheric baroclinicity is somewhat *** the diagnostics of the eddy energy budget, it is identified that the inefficiency of the barotropic energy conversion related to the barotropic governor mechanism does not favor the occurrence of the MWS. In contrast, weakened baroclinic energy conversion, buoyancy conversion, and generation of eddy available potential energy by diabatic heating are conducive to the occurrence of the MWS. In addition, Ural blocking in the upstream region of the MNPST may be another candidate mechanism associated with the MWS.

关键词： midwinter suppression North Pacific storm track anomalous atmospheric circulation eddy energy budget

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Wet flue gas desulfurization performance of 330 MW coal-fired power unit based on computational fluid dynamics region identification of flow pattern and transfer process

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Chinese Journal of Chemical Engineering 2021年第1期34卷 13-26页

作者： Jiangyuan Qu Nana Qi Kai Zhang lifeng li PengchengWang Beijing Key Laboratory of Emission Surveillance and Control for Thermal Power Generation North China Electric Power UniversityBeijing 102206China Key Laboratory of Power Station Energy Transfer Conversion and System(North China Electric Power University) Ministry of EducationBeijing 102206China Shanxi Hepo Power Generation Company limited Yangquan 045011China

Wet Flue Gas Desulfurization(WFGD)unit based upon spray scrubber has beenwidely employed to control SO_(2) emissions from flue gas in coal-fired power *** clarify the dependence of desulfurization performance on inter-phase transfer behaviors with non-ideal contacting patterns of flue gas and slurry droplets,three regions in spray scrubber are distinguished in terms of gas-slurry flow structures using CFD method in the Eulerian-Lagrangian framework.A comprehensive model is established by involving the transfer process between two phases and chemical reactions in aqueous phase,which is validatedwith the measured data froma WFGD scrubber of 330 MW coal-fired power *** results show that the overall uniformity degree of flue gas in whole scrubber is largely determined by the force-balanced droplets in the middle part of scrubber,which is dominated by counter-current *** momentum transfer behavior and SO_(2) chemical absorption process present the synchronicity with the evolution of gas-slurry flow pattern,whilst the heat transfer together with H_(2)O evaporation has little effect on overall absorption *** regions are firstly defined as Gas Inlet Region(GIR),Dominant Absorption Region(DAR)and Slurry Dispersed Region(SDR)from the bottom to top of ***_(2) is mainly scrubbed in DAR,which provides much more intensive interaction between two phases compared to GIR or SDR.A better understanding of the desulfurization process is obtained from the fundamental relationship between transport phenomena and chemical reactions based upon the complicated hydrodynamics of gas-slurry two-phase flow,which should be useful for designing and optimizing the scrubber in coal-fired power unit.

关键词： Wet flue gas desulfurization Gas-liquid flow Eulerian-Lagrangian model Flow pattern Transport processes Absorption

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Different Impacts of Madden–Julian Oscillation on Winter Rainfall over Southern China

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Journal of Meteorological Research 2021年第2期35卷 271-281页

作者： Xiong CHEN Jian liNG Chongyin li lifeng li Minghao YANG College of Meteorology and Oceanography National University of Defense TechnologyNanjing 211101 State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029 University of Chinese Academy of Sciences Chinese Academy of SciencesBeijing 100049

Winter rainfall over southern China is usually enhanced when Madden–Julian oscillation(MJO) is active over the Indian Ocean, but it can be weakened under certain conditions. Here, the diversity of MJO impacts on winter rainfall and its mechanisms are explored by using scenarios of enhanced and suppressed rainfall anomalies over southern China when MJO is active over the Indian Ocean. The combined effects of low-frequency background moisture and intraseasonal winds are the major contributors to the different rainfall anomalies. Anomalous circulation in mid–high latitudes, especially on intraseasonal timescales, is almost opposite in the two scenarios, which can modulate the response of extratropical atmosphere to MJO heating and then induces the different circulations over southern China. In the enhanced scenario, mid–high latitudes of Eurasia and southern China are dominated by positive and negative sea level pressure anomalies, respectively. The southerly over southern China and the South China Sea induced by MJO heating promotes the anomalous moisture convergence and ascending motion over southern China, resulting in the enhanced rainfall. In the suppressed scenario, however, the circulation in mid–high latitudes does not favor rainfall over southern China and leads to the northerly response to MJO heating over southern China, which enhances moisture divergence and weakens rainfall over southern China.

关键词： Madden–Julian oscillation(MJO) winter rainfall southern China moisture diagnoses

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Modulation of Madden-Julian Oscillation Activity by the Tropical Pacific-Indian Ocean Associated Mode

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Advances in Atmospheric Sciences 2020年第12期37卷 1375-1388页

作者： lifeng li Xin li Xiong CHEN Chongyin li Jianqi ZHANG Yulong SHAN College of Meteorology and Oceanography National University of Defense TechnologyNanjing 211101China State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China

In this study,the impacts of the tropical Pacific–Indian Ocean associated mode(PIOAM)on Madden–Julian Oscillation(MJO)activity were investigated using reanalysis *** the positive(negative)phase of the PIOAM,the amplitudes of MJO zonal wind and outgoing longwave radiation are significantly weakened(enhanced)over the Indian Ocean,while they are enhanced(weakened)over the central and eastern *** eastward propagation of the MJO can extend to the central Pacific in the positive phase of the PIOAM,whereas it is mainly confined to west of 160°E in the negative *** PIOAM impacts MJO activity by modifying the atmospheric circulation and moisture *** ascending(descending)motion and positive(negative)moisture anomalies occur over the western Indian Ocean and central-eastern Pacific(Maritime Continent and western Pacific)during the positive phase of the *** anomalous circulation is almost the opposite in the negative phases of the *** anomalous circulation and moisture can modulate the activity of the *** stronger moistening over the Indian Ocean induced by zonal and vertical moisture advection leads to the stronger MJO activity over the Indian Ocean in the negative phase of the *** the positive phase of the PIOAM,the MJO propagates farther east over the central Pacific owing to the stronger moistening there,which is mainly attributable to the meridional and vertical moisture advection,especially low-frequency background state moisture advection by the MJO’s meridional and vertical velocities.

关键词： tropical Pacific-Indian Ocean associated mode MJO moisture budget analysis anomalous circulation

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Preliminary animal studies on observation of injured spinal cord with intraoperative ultrasound backscatter microscopy

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Chinese Science Bulletin 2012年第18期57卷 2280-2284页

作者： HaiJun Niu lifeng li Kai liao XiaoGuang li YuBo Fan Beijing Univ Sch Biol Sci & Med Engn State Key Lab Software Dev Environm Minist Educ Biomechan & MechKey Lab Beijing 100191 Peoples R China

Many studies have shown that strategies of nerve regeneration and cell-based transplantation are valid based on animal models of spinal cord injury (SCI).To apply these strategies and bridge spinal cord defects,the identification and precise localization of lesions during spinal cord surgery is *** aim of the present experiment was to evaluate the capabilities of ultrasound backscatter microscopy (UBM) in identifying morphologic changes after *** laminectomy,high-resolution ultrasound images of the spinal cord were obtained in one normal and seven spinal cord-injured adult Wistar rats using a UBM system with a 55-MHz center frequency *** between histoanatomic and UBM images was also *** results showed that UBM can identify cysts after the experimental SCI is removed in adult *** addition,the glial scar formed in secondary injury showed obvious hyperechoic speckle in the UBM image and correlated with the histoanatomic *** has obvious clinical value in nerve regeneration and cell-based transplantation strategies in injured spinal cords.

关键词：脊髓损伤显微镜观察动物实验超声散射 Wistar大鼠超声图像细胞移植神经再生

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Deep-Ensemble Learning Method for Solar Resource Assessment of Complex Terrain Landscapes

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Energy Engineering 2024年第5期121卷 1329-1346页

作者： lifeng li Zaimin Yang Xiongping Yang Jiaming li Qianyufan Zhou Ping Yang Energy Development Research Institute China Southern Power GridGuangzhou510000China Corporate Headquarters China Southern Power GridGuangzhou510000China Guangdong Green Energy Key Laboratory South China University of TechnologyGuangzhou510000China

As the global demand for renewable energy grows,solar energy is gaining attention as a clean,sustainable energy *** assessment of solar energy resources is crucial for the siting and design of photovoltaic power *** study proposes an integrated deep learning-based photovoltaic resource assessment *** learning and deep learning methods are fused for photovoltaic resource assessment for the first *** proposed method combines the random forest,gated recurrent unit,and long short-term memory to effectively improve the accuracy and reliability of photovoltaic resource *** proposed method has strong adaptability and high accuracy even in the photovoltaic resource assessment of complex terrain and *** experimental results show that the proposed method outperforms the comparison algorithm in all evaluation indexes,indicating that the proposed method has higher accuracy and reliability in photovoltaic resource assessment with improved generalization performance traditional single algorithm.

关键词： Photovoltaic resource assessment deep learning ensemble learning random forest gated recurrent unit long short-term memory

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