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Enhanced service stability and thermoelectric performance in Cu_(2.−δSebased composites

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Science China Materials 2024年第7期67卷 2369-2370页

作者： pengfei Qiu Xun Shi State Key Laboratory of High Performance Ceramics and Superfine Microstructure Shanghai Institute of CeramicsChinese Academy of SciencesShanghai 200050China

Thermoelectric(TE)materials can directly convert the industrial waste heat into useful electricity based on the Seebeck effect,providing a promising way to tackle the environmental pollution and global energy crisis[1].In the past several decades,many new high-performance TE materials have been discovered to enrich the TE *** them,Cu_(2.−δSe-based TE materials,which are in line with the“phonon-liquid electron-crystal”concept,have sparked widespread interest due to the high TE figure-of-merit(ZT)and the combination of elements that are nontoxic and earth-abundant[2..In 2.12.Liu et al.[3]reported a ZT of 1.5 at 1000 K in the stoichiometric Cu_(2.*** alloying S at the Se-site,the ZT was enhanced to around 2.0 at 1000 K[4].Via incorporating carbon nanotubes,the ZT was further enhanced to 2.4 at 1000 K[5].Moreover,Yang et al.[6]and Zhou et al.[7]reported that the ZT of Cu_(2.Se/BiCuSeO composites can reach 2.7–2.8 around 1000 K.

关键词： composites BiCuSeO performance

Bayesian Optimized LightGBM model for predicting the fundamental vibrational period of masonry infilled RC frames

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Frontiers of Structural and Civil Engineering 2024年第7期18卷 1084-1102页

作者： Taimur RAHMAN pengfei ZHENG Shamima SULTANA Department of Civil Engineering World University of BangladeshDhaka 1230Bangladesh School of Civil Engineering Zhengzhou UniversityZhengzhou 450001China Department of Computer Science&Engineering University of Asia PacificDhaka 1205Bangladesh

The precise prediction of the fundamental vibrational period for reinforced concrete(RC)buildings with infilled walls is essential for structural design,especially earthquake-resistant *** learning models from previous studies,while boasting commendable accuracy in predicting the fundamental period,exhibit vulnerabilities due to lengthy training times and inherent dependence on pre-trained models,especially when engaging with continually evolving data *** predicament emphasizes the necessity for a model that adeptly balances predictive accuracy with robust adaptability and swift data *** latter should include consistent re-training ability as demanded by realtime,continuously updated data *** research implements an optimized Light Gradient Boosting Machine(LightGBM)model,highlighting its augmented predictive capabilities,realized through the astute use of Bayesian Optimization for hyperparameter tuning on the FP402. research data set,and illuminating its adaptability and efficiency in predictive *** results show that the R^(2. score of LightGBM model is 0.9995 and RMSE is 0.0178,while training speed is 2..2.times faster than that offered by XGBoost and 45.5 times faster than for Gradient ***,this study introduces a practical application through a streamlit-powered,web-based dashboard,enabling engineers to effortlessly utilize and augment the model,contributing data and ensuring precise fundamental period predictions,effectively bridging scholarly research and practical applications.

关键词： masonry-infilled RC frame fundamental period LightGBM FP402. research dataset machine learning data-driven approach Bayesian Optimization

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核主泵启动过程压力脉动和径向力研究

核动力工程 2017年第3期38卷 110-114页

作者：苏宋洲王鹏飞许忠斌阮晓东孔伟杰浙江大学化工机械研究所杭州310027 浙江大学城市学院工程学院杭州310015 浙江大学流体动力与机电系统国家重点实验室杭州310027 三门核电有限公司浙江三门317100

为研究核主泵启动过程中压力脉动和径向力的变化规律,根据AP1000启动过程的物性变化规律及参数设置,采用统计学方法对泵内无量纲压力脉动强度进行描述,采用频谱法分析了叶轮径向力。结果表明:导叶流道的压力脉动强度明显强于叶轮流道,... 详细信息

为研究核主泵启动过程中压力脉动和径向力的变化规律,根据AP1000启动过程的物性变化规律及参数设置,采用统计学方法对泵内无量纲压力脉动强度进行描述,采用频谱法分析了叶轮径向力。结果表明:导叶流道的压力脉动强度明显强于叶轮流道,随工作温度升高,强度递减;叶轮和压水室的压力脉动强度较弱,随工作温度升高,呈现不规律变化;叶轮径向力在叶频的1倍频和2.频的脉动幅值较小,随工作温度升高,呈现不规律变化;而叶轮径向力在5倍频的脉动幅值最大,且随工作温度升高,其值递减;核主泵偏离设计工作点运行于常温下会导致导叶流道压力脉动增强,导致主泵的径向振动增强。

关键词：核主泵启动过程物性压力脉动径向力

High-throughput screening of single-atom catalysts confined in monolayer black phosphorus for efficient nitrogen reduction reaction

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Nano Research 2024年第4期17卷 2360-2367页

作者： Xiao-Yan Li Manyi Duan pengfei Ou Department of Electrical and Computer Engineering University of TorontoTorontoOntario M5S 1A4Canada School of Physics and Electronic Engineering Sichuan Normal UniversityChengdu 610101China Department of Chemistry Northwestern UniversityEvanstonIL 60208USA

The discovery of metal-nitrogen centers as the active sites for electrolysis has aroused significant interest in utilizing single-atom catalysts for nitrogen reduction reaction(NRR).Properly designed nanostructured catalysts that strongly interact with nitrogen molecules(N_(2.)can promote adsorption and activation,thereby resulting in efficient catalysts with high stability,activity,and *** this study,using density functional theory calculations,we selected monolayer black phosphorus(BP)as the substrate and screened a series of single-atom transition metals confined in tri-coordinated and tetra-coordinated active centers(without and with N dopants)to electro-catalyze *** a result,we have identified two promising candidates(Hf_(1)-N_(1)P_(2.-1 and Tc_(1)-N_(4)),which exhibit not only low overpotentials of 0.56 and 0.49 V but also high thermodynamic and electrochemical stability,as well as good selectivity towards NRR over the competing hydrogen evolution *** also demonstrate the ability of Hf_(1)-N_(1)P_(2.-1 and Tc_(1)-N_(4) to activate and hydrogenate N_(2. by donating electrons and regulating charge *** study not only predicts new BP-based promising catalysts but also provides guidance for the rational design of high-performance NRR electrocatalysts under ambient conditions.

关键词： N_(2. electroreduction reaction single-atom catalysts black phosphorus density functional theory high-throughput calculations

蒸汽发生器换热管流量分配及其对核主泵入口流场的影响

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核动力工程 2018年第4期39卷 58-62页

作者：马腾跃王鹏飞许忠斌阮晓东孔伟杰浙江大学化工机械研究所杭州310027 浙江大学城市学院机械电子工程学系杭州310015 浙江大学流体动力与机电系统国家重点实验室杭州310027 三门核电有限公司浙江三门317100

为研究蒸汽发生器(SG)换热管流量分配及其对反应堆冷却剂泵(RCP)入口流场的影响,进行了蒸汽发生器的缩尺模型冷态实验,并以实验获得的数据为SG下封头的入流条件,对SG下封头进行数值建模,并采用计算流体力学(CFD)方法对其进行了三维流场... 详细信息

为研究蒸汽发生器(SG)换热管流量分配及其对反应堆冷却剂泵(RCP)入口流场的影响,进行了蒸汽发生器的缩尺模型冷态实验,并以实验获得的数据为SG下封头的入流条件,对SG下封头进行数值建模,并采用计算流体力学(CFD)方法对其进行了三维流场计算。结果表明:SG换热管存在较严重的流量分配不均,SG入口管会对其所正对部分的换热管的流量分配产生较大影响,使该部分流量增大,即形成高速区,而高速区周围会形成相对的低速区甚至回流区;在小流量时,换热管的沿程损失将对换热管的流量分配起主导作用;SG换热管内的不均匀流量分配会使SG出口管处的轴向速度更加紊乱,即在核主泵入口产生更加严重的入流畸变。

关键词：蒸汽发生器(SG) 核主泵非均匀入流流量分配

Ternary superhydrides for high-temperature superconductivity at low pressures

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National Science Review 2024年第7期11卷 12-14页

作者： pengfei Shan Liang Ma Jinguang Cheng Beijing National Laboratory for Condensed Matter Physics and Institute of Physics Chinese Academy of Sciences School of Physical Sciences University of Chinese Academy of Sciences Key Laboratory of Materials Physics Ministry of Education School of Physics and Microelectronics Zhengzhou University

The quest for room-temperature superconductivity(RTSC) has been a longstanding pursuit in physics since the discovery of superconductivity in *** to the conventional Bardeen-Cooper-Schrieffer theory, atomic metallic hydrogen holds great promise for achieving this goal due to its high Debye temperature and strong electron-phonon coupling.

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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 ~2.. 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 *** 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)

Reassessing the contributions of terrestrial waters to sea level variations in the South China Sea and its response to alternating ENSO events

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Science China Earth Sciences 2024年第7期67卷 2253-2267页

作者： pengfei YANG Hok Sum FOK Zhongtian MA MOE Key Laboratory of Geospace Environment and Geodesy&MNR Key Laboratory of Geophysical Geodesy School of Geodesy and GeomaticsWuhan UniversityWuhan 430079China Hubei Luojia Laboratory Wuhan 730079China Department of Land Surveying and Geo-Informatics The Hong Kong Polytechnic UniversityHong Kong 999077China

Regional sea level variability is linked to regional terrestrial water and the El Ni?o-Southern Oscillation(ENSO).This study assessed the relationships between the sea level variations in the South China Sea(SCS)and ENSO,the impact of terrestrial water storage(TWS)on non-steric sea level(NSSL),and the contributions of steric sea level(SSL)and NSSL to sea level anomaly(SLA),*** 2.03 to 2.15,the SLAs exhibited a long-term trend of 6.65±0.78 mm/yr,which was primarily attributed to the ***,during 2.03-2.15,ENSO events alternating with varying intensities might also be responsible for the unusually high SLA *** to the SSLs,the NSSLs contributed the seasonal signals to the SLAs,while the NSSLs changes were largely explained by the TWS in the Mekong River Basin at the seasonal scale and in the Pearl River Basin and Red River Basin at other time *** contrast to the TWS,the contributions of precipitation and evapotranspiration were relatively minor.A negative correlation between the sea level variations and ENSO was also found,with cross-correlation coefficients between the oceanic Ni?o index and SLAs/SSLs/NSSLs of -0.36/-0.37/-0.62.with lags of 2.3/2.months,*** findings systematically reassessed the contributions of different components to the sea level *** study provided a benchmark for in-depth analysis of the impacts of terrestrial water and other potential causes on sea level rise in the SCS.

关键词： South China Sea Sea level variations Terrestrial water storage ENSO

Prediction of subsurface settlement induced by shield tunnelling in sandy cobble stratum

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第1期16卷 192-212页

作者： Fan Wang Xiuli Du pengfei Li Key Laboratory of Urban Security and Disaster Engineering Ministry of EducationBeijing University of TechnologyBeijing100124China

This study focuses on the analytical prediction of subsurface settlement induced by shield tunnelling in sandy cobble stratum considering the volumetric deformation modes of the soil above the tunnel crown.A series of numerical analyses is performed to examine the effects of cover depth ratio(C/D),tunnel volume loss rate(h t)and volumetric block proportion(VBP)on the characteristics of subsurface settle-ment trough and soil volume *** the ground loss variation with depth,three modes are deduced from the volumetric deformation responses of the soil above the tunnel ***,analytical solutions to predict subsurface settlement for each mode are presented using stochastic medium *** influences of C/D,h t and VBP on the key parameters(i.e.B and N)in the analytical expressions are discussed to determine the fitting formulae of B and ***,the proposed analytical solutions are validated by the comparisons with the results of model test and numerical *** show that the fitting formulae provide a convenient and reliable way to evaluate the key ***,the analytical solutions are reasonable and available in predicting the subsurface settlement induced by shield tunnelling in sandy cobble stratum.

关键词： Shield tunnelling Sandy cobble stratum Subsurface settlement Volumetric deformation mode Stochastic medium theory