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Nanoscopic tribological characteristics of a cryogenically cycled Zr-based metallic glass

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Science China(Physics,Mechanics & Astronomy) 2024年第6期67卷 113-126页

作者： Qian Jia Qiaosheng Xia Qing Zhou Yucheng Wang Yue Ren Yu meng haifeng Wang Feng Zhou State Key Laboratory of Solidification Processing Center of Advanced Lubrication and Seal MaterialsNorthwestern Polytechnical UniversityXi’an 710072China Shaanxi Key Laboratory of Surface Engineering and Remanufacturing Xi’an UniversityXi’an 710065China State Key Laboratory of Solid Lubrication Lanzhou Institute of Chemical PhysicsChinese Academy of SciencesLanzhou 730000China

Optimized macroscopic tribological behavior can be anticipated in metallic glasses(MGs)by cryogenic cycling treatment(CCT),which is attributed to enhanced ***,the intrinsic friction mechanisms of MGs induced by cryogenic rejuvenation are still poorly *** the present study,nanoscopic wear tests were conducted on the Zr-based MGs surface with different CCT cycles using atomic force microscopy(AFM).After CCT treatment with 100 cycles,the MG displays the highest adhesion and ploughing frictions,but significantly improved anti-wear *** tests and molecular dynamics simulations disclose that the increased adhesion is attributed to the dominance of liquid-like regions in the CCT-treated MGs,and the impact of reduced hardness and weak elastic recovery results in the deteriorated ploughing *** enhanced plasticity effectively dissipates the strain from the AFM tip through multiple shear bands and weakens the adhesion during deformation,giving rise to excellent wear *** study elucidates the promoting effect of CCT on the outstanding antiwear performance of MGs,and is helpful for the development of novel alloys.

关键词： metallic glasses cryogenic cycling treatment nanoscope wear friction mechanism

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THE EFFECTS OF HARVESTING AND TIME DELAY ON PREDATOR-PREY SYSTEMS WITH BEDDINGTON-DEANGELIS FUNCTIONAL RESPONSE

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International Journal of Biomathematics 2012年第1期5卷 103-125页

作者： XINYOU meng haifeng HUO XIAOBING ZHANG School of Science Lanzhou University of Technology Lanzhou 730050 P. R. China

The combined effects of harvesting and time delay on predator-prey systems with Beddington-DeAngelis functional response are studied. The region of stability in model with harvesting of the predator, local stability of equilibria and the existence of Hopf bifurcation are obtained by analyzing the associated characteristic equation due to the two-parameter geometric criteria developed by Ma, Feng and Lu [Discrete Contin. Dyn. Syst. Set B 9 （2008） 397-413]. The global stability of the positive equilibrium is inves- tigated by the comparison theorem. Furthermore, local stability of steady states and the existence of Hopf bifurcation for prey harvesting are also considered. Numerical simulations are given to illustrate our theoretical findings.

关键词： Stability Hopf bifurcation harvesting time delay Beddington-DeAngelis predator-prey.

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中国计量院光伏计量研究综述

计量科学与技术 2024年第5期68卷 92-99,126页

作者：孟海凤张俊超刘文德徐楠王萌张碧丰蔡川满帅邓文浩熊利民甘海勇中国计量科学研究院北京100029

光伏发电是最有前途的可再生清洁能源技术之一,而中国已成为世界上最大的光伏产品生产国、应用国和出口国。准确可靠地测量光伏产品的光电性能参数,对光伏领域相关的科学研究和产业发展至关重要。基于中国计量科学研究院建立的量值溯源... 详细信息

光伏发电是最有前途的可再生清洁能源技术之一,而中国已成为世界上最大的光伏产品生产国、应用国和出口国。准确可靠地测量光伏产品的光电性能参数,对光伏领域相关的科学研究和产业发展至关重要。基于中国计量科学研究院建立的量值溯源和传递体系,我国光伏领域实现了关键参数的量值有效溯源和传递。综述了我国光伏领域量值溯源传递链的研究和建立情况,即从相关的最高标准——低温辐射计到终端应用光伏产品,并对下一阶段的研究进行展望。

关键词：计量学光伏溯源传递光电性能

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Facet-dependent CuO/{010}BiVO_(4)S-scheme photocatalyst enhanced peroxymonosulfate activation for efficient norfloxacin removal

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Journal of Materials Science & Technology 2024年第7期174卷 30-43页

作者： Tongyu Han haifeng Shi Yigang Chen School of Science Jiangnan UniversityWuxi 214122China Department of General Surgery Jiangnan University Medical CenterWuxi 214002China

Rapid recombination of charge carriers and sluggish Cu^(2+)/Cu^(+)conversion rate in Cu-based photocatalysts hinder the improvement of the peroxymonosulfate(PMS)activation ***,a novel S-scheme system was successfully built through hydrothermal and in-situ calcination methods to activate PMS for norfloxacin(NOR)degradation,which combined CuO with BiVO_(4)(BVO)containing surface *** UV-vis spectra manifested that BVO displayed excellent visible light absorption performance after compounding with CuO,and the light absorption threshold of CuO/BVO was about 600 *** to the existence of surface heterojunction in BVO,the photoinduced electrons,and holes would trans-fer to{010}and{110}facets,*** construction of S-scheme heterojunction further facilitated the accumulation of electrons on CuO,thus realizing the spatial separation of charge *** addi-tion,the electrons gathered on the CuO expedited the Cu^(2+)/Cu^(+)cycle,thereby improving the activation efficiency of *** this basis,the NOR removal capacity of 5CuO/BVO composites was obviously en-hanced,which was 3.65 and 2.45 times that of CuO and ***,the influence of ambient pH and PMS dosage on the photocatalytic performance of CuO/BVO was *** the analysis of NOR degradation pathways and degradation products,it was found that the toxicity threat of NOR to the environment was reduced during the degradation *** to the XPS results,forming the S-scheme heterojunction accelerated the Cu^(2+)/Cu^(+)redox cycle during the PMS activating ***,photoluminescence(PL)and time-resolved photoluminescence(TRPL)analysis demonstrated that the CuO/BVO composites exhibited eminent ability for charge *** possible mechanism of charge transfer was assumed by exploring reactive species and the energy band structure of *** sum up,this research provides a new perspective on boosting PMS activation to purify antibiotics

关键词： Norfloxacin degradation Peroxymonosulfate S-scheme heterojunction Surface heterojunction Charge separation

Study on Effect of Time Factor on Tree Growth

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Agricultural Biotechnology 2018年第2期7卷 96-100页

作者： haifeng meng Lu LIU Chuanyou CHEN Chunyan CHEN Hui LI Forestry Bureau of Tai'an City Tai'an 271000China Culaishan Forest Farm of Tai'an City Tai'an 271000China

According to the data of analytic trees,an empirical equation of tree growth was constructed,with annual growth as variable and time and annual precipitation as independent variables. Through arithmetical operation including derivation of function and so on,the effect of precipitation on tree growth was studied through the rejection of effect of time factor.

关键词： Empirical equation Analytic tree Time FactorHome

Dual metal ions/BNQDs boost PMS activation over copper tungstate photocatalyst for antibiotic removal:Intermediate,toxicity assessment and mechanism

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Journal of Materials Science & Technology 2024年第3期170卷 11-24页

作者： Ruyao Chen Haiyue Zhang Yuming Dong haifeng Shi School of Science Jiangnan UniversityWuxi214122China The Key Laboratory of Synthetic and Biological Colloids Ministry of EducationJiangnan UniversityWuxi214122China National Laboratory of Solid State Microstructures Nanjing UniversityNanjing210093China

In the metal-based peroxymonosulfate(PMS)activation process,the sluggish surface redox cycle of metal ions generally hampered the efficiency of PMS activation for pollutant ***,Codoped CuWO 4/BN quantum dots(CW/Co/BNQDs)photocatalysts were developed to realize Cu^(2+)/Cu+and Co^(2+)/Co^(3+)dual ions redox cycles for PMS activation,which would facilitate the tetracycline(TC)***/4Co/2BNQDs could degrade 94.8%TC within 30 min in PMS/Vis system,and the apparent rate constant of CW/4Co/2BNQDs was 2.7 times and 1.2 times higher than those of CW and CW/4Co,*** improved TC degradation performance could be attributed to the synergetic effect between BNQDs and dual redox cycles.X-ray photoelectron spectroscopy(XPS)spectra of samples before and after the reaction demonstrated that BNQDs were beneficial for accelerating the Cu^(2+)/Cu+and Co^(2+)/Co^(3+)redox cycles in CW/4Co/2BNQDs,further boosting the activation of PMS in TC *** of different radical scavengers revealed that the SO_(4)^(·−)/·OH/h+/^(1)O_(2)reactive species participated in the PMS activation for the TC degradation *** possible TC degradation pathway and intermediate toxicity were detailed *** addition,CW/4Co/2BNQDs exhibited outstanding photocatalytic activity over five consecutive cycles,which illustrated that it was supposed to be a reliable PMS activator over antibiotic elimination for practical *** this work shed new light on constructing dual redox cycles for efficient PMS activation.

关键词： Dual redox cycles Photocatalysis Peroxymonosulfate BN quantum dots Toxicity assessment

Asymmetric Hydrogenation of Phenanthridines with Chiral Boranes

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Chinese Journal of Chemistry 2024年第6期42卷 631-635页

作者： Guangyu Cui Xiangqing Feng haifeng Du Beijing National Laboratory for Molecular Sciences CAS Key Laboratory of Molecular Recognition and FunctionInstitute of ChemistryChinese Academy of SciencesBeijing100190 China University of Chinese Academy of Sciences Beijing100049 China

The asymmetric hydrogenation of N-heteroarenes provides an efficient method for the synthesis of optically active cyclic secondary *** this paper,we described an asymmetric hydrogenation of phenanthridines using a chiral mono-alkene-derived borane.A variety of dihydrophenanthridines were furnished in high yields with up to 93%*** current catalytic system was very sensitive for the steric hindrance of *** substituents at one phenyl group of phenanthridines were required to obtain the high *** large substituents on the carbon of the C=N bonds would diminish the reactivity sharply.

关键词： Asymmetric catalysis Hydrogenation Nitrogen heterocycles Phenanthridines Frustrated Lewis pairs Chiral boranes

Reducing idleness in financial cloud services via multi-objective evolutionary reinforcement learning based load balancer

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Science China(Information Sciences) 2024年第2期67卷 20-40页

作者： Peng YANG Laoming ZHANG haifeng LIU Guiying LI Department of Statistics and Data Science Southern University of Science and Technology Guangdong Provincial Key Laboratory of Brain-Inspired Intelligent Computation Department of Computer Science and EngineeringSouthern University of Science and Technology Academy for Advanced Interdisciplinary Studies Southern University of Science and Technology Guangdong OPPO Mobile Telecommunications Corp. Ltd Research Institute of Trustworthy Autonomous Systems Southern University of Science and Technology

In recent years, various companies have started to shift their data services from traditional data centers to the cloud. One of the major motivations is to save on operational costs with the aid of cloud elasticity. This paper discusses an emerging need from financial services to reduce the incidence of idle servers retaining very few user connections, without disconnecting them from the server side. This paper considers this need as a bi-objective online load balancing problem. A neural network based scalable policy is designed to route user requests to varied numbers of servers for the required elasticity. An evolutionary multi-objective training framework is proposed to optimize the weights of the policy. Not only is the new objective of idleness reduced by over 130% more than traditional industrial solutions, but the original load balancing objective itself is also slightly improved. Extensive simulations with both synthetic and real-world data help reveal the detailed applicability of the proposed method to the emergent problem of reducing idleness in financial services.

关键词： evolutionary reinforcement learning evolutionary multi-objective optimization load balance cloud computing

Asymmetric Partial Hydrosilylation of 2,2-Difluoro-1,3-diketones with Chiral Frustrated Lewis Pairs

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Chinese Journal of Chemistry 2024年第8期42卷 853-857页

作者： Ting Liu Xiangqing Feng haifeng Du Beijing National Laboratory for Molecular Sciences CAS Key Laboratory of Molecular Recognition and FunctionInstitute of ChemistryChinese Academy of SciencesBeijing100190 China University of Chinese Academy of Sciences Beijing100049 China

Comprehensive Summary,The asymmetric partial reduction of 1,3-diketones stands as a straightforward pathway to access optically active β-hydroxyketones. In this paper, an asymmetric Piers-type hydrosilylation of 2,2-difluoro-1,3-diketones was successfully realized by using a frustrated Lewis pair of chiral borane and tricyclohexylphosphine as a catalyst, delivering a variety of α,α-difluoro-β-hydroxyketones in high yields with up to 99% ee. Significantly, no over-reduced diol products were observed even with an excess amount of silanes. The product can be conveniently converted to α,α-difluoro-β-hydroxyester or 1,3-anti-diol via an oxidation with m-CPBA or a reduction with DIBAL-H without obvious loss of ee.

关键词： Asymmetric catalysis Hydrosilylation Ketones Frustrated Lewis pairs Chiral boranes