检索结果-南通市图书馆

Effect of Interface Form on Creep Failure and Life of Dissimilar Metal Welds Involving Nickel-Based Weld Metal and Ferritic Base Metal

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Mechanical Engineering 2024年第1期37卷 265-285页

作者： Xiaogang Li junfeng Nie Xin Wang Kejian Li Haiquan zhang Institute of Nuclear and New Energy Technology Key Laboratory of Advanced Reactor Engineering and Safety of Ministry of EducationTsinghua UniversityBeijing 100084China Department of Mechanical Engineering Tsinghua UniversityBeijing 100084China

For dissimilar metal welds(DMWs)involving nickel-based weld metal(WM)and ferritic heat resistant steel base metal(BM)in power plants,there must be an interface between WM and BM,and this interface suffers mechanical and microstructure mismatches and is often the rupture location of premature failure.In this study,a new form of WM/BM interface form,namely double Y-type interface was designed for the DMWs.Creep behaviors and life of DMWs containing double Y-type interface and conventional I-type interface were compared by finite element analysis and creep tests,and creep failure mechanisms were investigated by stress-strain analysis and microstructure characterization.By applying double Y-type interface instead of conventional I-type interface,failure location of DMW could be shifted from the WM/ferritic heat-affected zone(HAZ)interface into the ferritic HAZ or even the ferritic BM,and the failure mode change improved the creep life of DMW.The interface premature failure of I-type interface DMW was related to the coupling effect of microstructure degradation,stress and strain concentrations,and oxide notch on the WM/HAZ interface.The creep failure of double Y-type interface DMW was the result of Type IV fracture due to the creep voids and micro-cracks on fine-grain boundaries in HAZ,which was a result of the matrix softening of HAZ and lack of precipitate pinning at fine-grain boundaries.The double Y-type interface form separated the stress and strain concentrations in DMW from the WM/HAZ interface,preventing the trigger effect of oxide notch on interface failure and inhibiting the interfacial microstructure cracking.It is a novel scheme to prolong creep life and enhance reliability of DMW,by means of optimizing the interface form,decoupling the damage factors from WM/HAZ interface,and then changing the failure mechanism and shifting the failure location.

关键词： Dissimilar metal weld Nickel-based weld metal Ferritic heat resistant steel Interface Creep strain Microstructure Failure mechanism Creep life

Characteristics and sources of peroxyacetyl nitrate(PAN)in the rural North China Plain:Results from1-year continuous observations

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Environmental Sciences 2024年第4期138卷 719-731页

作者： Xin Liu Xiaowei He Chenglong zhang Yifei Song Shuyang Xie Chengtang Liu Pengfei Liu Yuanyuan zhang Yujing Mu junfeng Liu Research Center for Eco-Environmental Sciences Chinese Academy of SciencesBeijing 100085China University of Chinese Academy of Sciences Beijing 100049China

Peroxyacetyl nitrate(PAN)is an important photochemical pollutant in the troposphere,whereas long-term measurements are scarce in rural areas in North China Plain(NCP),resulting in unclear seasonal variations and sources of PAN in rural NCP.In this study,we conducted a 1-year observation of PAN during 2021-2022 at the rural NCP site.The average concentrations of PAN were 1.10,0.75,0.65,and 0.88 ppbv in spring,summer,autumn,and winter,respectively,with a 1-year average of 0.81±0.60 ppbv.Calculations indicate that the loss of PAN through thermal decomposition in summer accounts for 43.2% of the total formed PAN,which is an important reason for the low concentration of PAN in summer.We speculate that since the correlation between PAN and O_(3) in winter is significantly lower than that in other seasons,the observed regional transport of PAN cannot be ignored in winter.Through budget analysis,regional transport accounted for 12.8% and 55.9% of the observed PAN on the spring and winter pollution days,respectively,which showed that regional transport played key roles during the photochemical pollution of the rural NCP in winter.The potential source contribution function revealed that the transported PAN mainly comes from southern Hebei in spring.In winter,the transported PAN was mainly from Langfang,Hengshui,and southern Beijing.Our findings may aid in understanding PAN variations in different seasons in rural areas and highlight the impact of regional transport on the PAN budget.

关键词： Photochemical pollution Peroxyacetyl nitrate(PAN) Seasonal variations Regional transport Rural area

Nickel-Catalyzed Regio-and Stereoselective Defluorinative Arylation of gem-Difluorinated Cyclopropanes

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Chemistry 2024年第8期42卷 823-828页

作者： Shutao Qi Yunkai Hua Liangkai Pan junfeng Yang Junliang zhang Department of Chemistry Fudan University2005 Songhu RoadShanghai200438 China Fudan zhangjiang Institute Shanghai201203 China School of Chemistry and Chemical Engineering Henan Normal UniversityXinxiangHenan 453007China

Comprehensive Summary,Herein,we report nickel-catalyzed cross-coupling of gem-difluorinated cyclopropanes with boronic acids,providing the corresponding arylated 2-fluoroallylic scaffolds.This approach used commercially available phosphine ligand Xantphos to obtain monofluorinated alkenes with high regioselectivity and Z-stereoselectivity.Mechanistic studies proposed a Ni(II)-fluoroallyl pathway and excluded the radical pathway.

关键词： Nickel Monofluoroolefin Cyclopropane Regioselectivity Stereoselectivity C-C coupling Cross-coupling Synthetic methods

Glycine-β-cyclodextrin-assisted cometabolism of phenanthrene and pyrene by Pseudomonas stutzeri DJP 1 from marine sediment

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Oceanology and Limnology 2024年第2期42卷 560-569页

作者： junfeng JIANG Weijun TIAN Zhiyang LU Meile CHU Huimin CAO Dantong zhang College of Environmental Science and Engineering Ocean University of ChinaQingdao 266100China Key Laboratory of Marine Environment and Ecology Ministry of EducationQingdao 266100China

Cometabolic degradation is currently an effective and extensively way to remove high molecular weight polycyclic aromatic hydrocarbons(HMW-PAHs).Unfortunately,due to low bio-accessibility and high biotoxicity,the cometabolic degradation rate of HMW-PAHs is limited.Glycine-β-cyclodextrin(GCD)was obtained through amino modification ofβ-cyclodextrin(BCD)and added to cometabolic system of phenanthrene(PHE)and pyrene(PYR)to assist PYR biodegradation.Results show that the addition of GCD(100 mg/L)effectively improved the removal rate of PYR(20 mg/L)by 42.3%.GCD appeared to increase the bio-accessibility and reduce the biotoxicity of PHE and PYR,and then promoted the growth of Pseudomonas stutzeri DJP1 and stimulated the elevation of dehydrogenase(DHA)and catechol 12 dioxygenase(C12O)activities.The phthalate metabolic pathway was accelerated,which improved the cometabolic degradation.This study provided a new reference for the cometabolic degradation of HMW-PAHs.

关键词： cometabolism phenanthrene pyrene glycine-β-cyclodextrin biological accessibility biotoxicity

Microstructures and Properties of Biomedical Mg-Zn-Sn-Zr Rolled Alloys

在线全文

学校读者我要写书评

暂无评论

Journal of Wuhan University of Technology(Materials Science) 2024年第3期39卷 766-773页

作者：周生刚 zhang Daxin XU Yang DUAN Jihao LI Tao LIU junfeng WANG Peng 曹勇 Faculty of Material Science and Engineering Kunming University of Science and TechnologyKunming 650093China

The as-cast Mg-2.0Zn-1.5Sn-xZr(x=0,0.4,0.6,0.8,1.0 wt%)alloy was rolled with the pressure less than 5%each time.The microstructure,mechanical properties,corrosion properties and biocompatibility of the alloy were investigated.The microstructure of the alloy was observed and analyzed by scanning electron microscope,and the tensile test was carried out by universal tensile machine.The corrosion resistance of the alloy in Hank's solution was studied by hydrogen evolution experiment and electrochemical test,and the biocompatibility of the alloy was tested by L929 cells.The results show that Mg-2Zn-1.5Sn-xZr alloy has excellent mechanical properties.The elongation of Mg-2Zn-1.5Sn-xZr alloy decreases with the increase of Zr content,but the tensile strength first increases and then decreases with the increase of Zr concentration.When the Zr content is 0.8 wt%,the maximum tensile strength of the alloy is 235 MPa.The results of hydrogen evolution experiment and electrochemical analysis show that the corrosion resistance of the alloy is the best when the Zr content is 0.8 wt%,and all the five alloys have high biocompatibility.In conclusion,the rolled alloy has good properties and has broad application prospects in the field of biomaterials.

关键词： magnesium alloy corrosion performance mechanical properties biocompatibility

Comb-based photonic neural population for parallel and nonlinear processing

在线全文

学校读者我要写书评

暂无评论

Photonics Research 2022年第1期10卷 174-182页

作者： BOWEN MA junfeng zhang WEIWEN ZOU State Key Laboratory of Advanced Optical Communication Systems and Networks Intelligent Microwave Lightwave Integration Innovation Center(imLic)Department of Electronic EngineeringShanghai Jiao Tong UniversityShanghai 200240China

It is believed that neural information representation and processing relies on the neural population instead of a single neuron.In neuromorphic photonics,photonic neurons in the form of nonlinear responses have been extensively studied in single devices and temporal nodes.However,to construct a photonic neural population(PNP),the process of scaling up and massive interconnections remain challenging considering the physical complexity and response latency.Here,we propose a comb-based PNP interconnected by carrier coupling with superior scalability.Two unique properties of neural population are theoretically and experimentally demonstrated in the comb-based PNP,including nonlinear response curves and population activities coding.A classification task of three input patterns with dual radio-frequency(RF) tones is successfully implemented in a time-efficient manner,which allows the comb-based PNP to make effective use of the ultra-broad bandwidth of photonics for parallel and nonlinear processing.

关键词： nonlinear scaling neural

A subspace based method for modelling building’s thermal dynamic in district heating system and parameter extrapolation verification

在线全文

学校读者我要写书评

暂无评论

Building Simulation 2023年第11期16卷 2145-2158页

作者： junfeng zhang Lanbin Liu Yameng Liu University of Science and Technology Beijing 30 Xueyuan RoadBeijing100083China Beijing Nuanliu Technology Co. Ltd.Beijing100083China

The district heating system(DHS)consumes a lot of energy in winter,and its control accuracy needs to be improved urgently.To apply advanced process control(APC)in DHS,the thermal dynamic model of the existing buildings is essential.This paper uses the subspace method which is a data-driven approach for modelling the thermal dynamics of the building.The model’s performance is analyzed using the collected data,and the differences compared to the classical methods are also analyzed.The method reduces the RMSE by about 20%compared with the ARX model for the same complexity.Subsequently,the analysis of the training residuals indicates that the estimate of periodic intra-building disturbance can be obtained by minimizing the training residuals.By introducing the estimated disturbance function,the RMSE on the test set is further reduced by 26%.At the end of the article,a simple parameter extrapolation experiment is conducted,and the result shows that the parameters can be extrapolated to other buildings without large errors.

关键词： modelling district heating system state-space ARX thermal dynamics

Rapid characterization of non-volatile phenolic compounds reveals the reliable chemical markers for authentication of traditional Chinese medicine Xiang-ru among confusing Elsholtzia species

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Natural Medicines 2024年第4期22卷 375-384页

作者： ZENG Zhen zhang Chen HU Jiadong WANG Feiyan WU Ziding WANG Jing zhang Jun YANG Shuda CHEN junfeng LI Mingming TONG Qi QIU Shi CHEN Wansheng The SATCM Key Laboratory for New Resources&Quality Evaluation of Chinese Medicine Institute of Chinese Materia MedicaShanghai University of Traditional Chinese MedicineShanghai 201203China Department of Pharmacy Second Affiliated Hospital of Navy Medical UniversityShanghai 200003China Kunming Plant Classification Biotechnology Co. Ltd.Kunming 650500China School of Pharmaceutical Sciences and Yunnan Key Laboratory of Pharmacology for Natural Products Kunming Medical UniversityKunming 650500China State Key Laboratory for Quality Ensurance and Sustainable Use of Dao-di Herbs Beijing100700China

The aerial parts of Mosla chinensis Maxim.and Mosla chinensis cv.'Jiangxiangru'(MCJ)are widely utilized in traditional Chinese medicine(TCM),known collectively as Xiang-ru.However,due to clinical effectiveness concerns and frequent misidentification,the original plants have increasingly been substituted by various species within the genera Elsholtzia and Mosla.The challenge in distinguishing between these genera arises from their similar morphological and metabolic profiles.To address this issue,our study introduced a rapid method for metabolic characterization,employing high-resolution mass spectrometry-based metabolomics.Through detailed biosynthetic and chemometric analyses,we pinpointed five phenolic compounds—salviaflaside,cynaroside,scutellarein-7-O-D-glucoside,rutin,and vicenin-2—among 203 identified compounds,as reliable chemical markers for distinguishing Xiang-ru from closely related Elsholtzia species.This methodology holds promise for broad application in the analysis of plant aerial parts,especially in verifying the authenticity of aromatic traditional medicinal plants.Our findings underscore the importance of non-volatile compounds as dependable chemical markers in the authentication process of aromatic traditional medicinal plants.

关键词： Genus Elsholtzia Genus Mosla Traditional Chinese medicine Xiang-ru Non-volatile phenolic compounds Liquid chromatography-mass spectrometry

A novel silver-doped nickel oxide hole-selective contact for crystalline silicon heterojunction solar cells

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Frontiers of Chemical Science and Engineering 2024年第2期18卷 93-101页

作者： junfeng Zhao Xudong Yang Zhongqing zhang Shengpeng Xie Fangfang Liu Anjun Han Zhengxin Liu Yun Sun Wei Liu Key Laboratory of Photoelectronic Thin Film Devices and Technology of Tianjin Engineering Research Center of Thin Film Photoelectronic TechnologyInstitute of Photoelectronic Thin Film Devices and Technology of Nankai University(Ministry of Education)Tianjin 300350China Shanghai Institute of Microsystem and Information Technology Chinese Academy of SciencesShanghai 201800China

Based on its band alignment,p-type nickel oxide(NiO_(x))is an excellent candidate material for hole transport layers in crystalline silicon heterojunction solar cells,as it has a smallΔEV and largeΔEC with crystalline silicon.Herein,to overcome the poor hole selectivity of stoichiometric NiO_(x) due to its low carrier concentration and conductivity,silver-doped nickel oxide(NiO_(x):Ag)hole transport layers with high carrier concentrations were prepared by co-sputtering high-purity silver sheets and pure NiO_(x) targets.The improved electrical conductivity of NiO_(x) was attributed to the holes generated by the Ag^(+)substituents for Ni^(2+),and moreover,the introduction of Ag^(+)also increased the amount of Ni^(3+)present,both of which increased the carrier concentration in NiO_(x).Ag^(+)doping also reduced the c-Si/NiO_(x) contact resistivity and improved the hole-selective contact with NiO_(x).Furthermore,the problems of particle clusters and interfacial defects on the surfaces of NiO_(x):Ag films were solved by UV-ozone oxidation and high-temperature annealing,which facilitated separation and transport of carriers at the c-Si/NiO_(x) interface.The constructed c-Si/NiO_(x):Ag solar cell exhibited an increase in open-circuit voltage from 490 to 596 mV and achieved a conversion efficiency of 14.4%.

关键词： band alignment nickel oxide hole transport layer silver-doped nickel oxide UV-ozone