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Journal of Integrative Agriculture 2017年第8期16卷 1852-1864页

作者： LI Hong-qing zheng fei ZHAO Yao-yang Institute of National Land Resources Management Hohai UniversityNanjing 210098P.R.China

Intensive agriculture has caused unintended environmental consequences, such as water quality degradation. It is necessary for policymakers to make proper planning of sustainable agricultural development. Using a Pressure-State-Response （PSR） framework, we conducted surveys focused on farmer behavior toward agriculture and environmental protection in 2009 and 2011. The surveys indicated that farmer behavior was complex and contradictory, and caused some environmental effects. Therefore, we used normative landscape scenario method to develop two scenarios. Both scenarios emphasized on stable economic growth along with water quality improvement and presented good effects. A feedback survey was organized in 2013 to interpret farmers＇ perceptions of the alternative scenarios. The results indicate Scenario I is likely to be accepted by farmers; however, the beautiful rural landscape in *** represents what farmers want, and Scenario I or II can be achieved by changing farm behavior in the future. By logistic regression model analysis, increasing agriculture benefits and new technology popularization were key factors affecting farmer behavior. Relevant policy implications on farmers were proposed. This paper showed how important to understand farmer behavior and perceptions to agricultural development, and a description of the alternative scenarios and policy implications are meaningful for policymakers to manage nature resources.

关键词： farmer behavior alternative scenarios PSR framework water quality

Carbides Evolution in 12Cr Martensitic Heat-resistant Steel with Life Depletion for Long-term Service

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Journal of Iron and Steel Research International 2015年第3期22卷 250-255页

作者： zheng-fei HU Da-hai HE Fan MO School of Materials Science and Engineering Tongji University

Evaluating the residual life of exposed components in power industry is a very important procedure inroutine examination. The microstructures of a series of X20CrMoV12.1 martensitic superheater tube samples in a boiler in different service periods were investigated extensively to extract a quantitative relationship. During long-term service from start to rupture, hardness decreased monotonically with life depletion, and the decrease of hardness in prior austenite grain boundary was steeper than that in the matrix. Microstructure observation showed obvious damage characteristics, including carbide coarsening and martensite decomposing, and the martensite structure decomposed completely in rupture state. The morphology, distribution and composition of the main precipitates M23 C6 varied distinctly. The aspect ratio of coarsened carbides along grain boundary increased several fold with respect to their original size. The composition of coarsened M23 C6 carbide shows the most regular trend of Cr enrichment and the statistical result of Cr enrichment in M23 C6 shows a linear correlation between the ratio of Cr to Fe and service time to the power of 3/2, which may be considered as an index of material degradation due to long-term service exposure.

关键词： 12Cr martensitic heat-resistant steel carbide microstructure creep damage element enrichment longterm service

A possible bias of simulating the post-2000 changing ENSO

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Science Bulletin 2015年第21期60卷 1850-1857页

作者： fei zheng Wen Zhang Jinyi Yu Quanliang Chen International Center for Climate and Environment Science (ICCES) Institute of Atmospheric Physics Chinese Academy of Sciences College of Atmospheric Sciences Chengdu University of Information Technology Department of Earth System Science University of California

Since the late 1990s, a climate shift has occurred over the tropical Pacific that is characterized with a La Nifia-like mean state. Coincident with this climate shift, climate models＇ skills in predicting the El Nifio Southern Oscillation （ENSO） events in the 2000s are sig- nificantly lower than in the 1980s-1990s, A common bias is likely to exist in contemporary ENSO models that got amplified after the climate shift. In this study, we identify this model bias to be the wind-sea surface temperature coupling processes over the tropical Pacific. Evidence is presented to show that this coupling process experienced an obvious shift around year 2000 in its coupling strength and coupling center. A simple ENSO coupled model is used to demonstrate that the changing properties of the post-2000 ENSO events can be more realistically simulated if this model bias is alleviated.

关键词： ENSO Wind-SST coupling - Biascorrection Climate shift

Parallelization of spherical discontinuous deformation analysis(SDDA) for geotechnical problems based on cloud computing environment

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Science China(Technological Sciences) 2021年第9期64卷 1971-1980页

作者： JIAO Yu-Yong WU ZeYang zheng fei ZHAO Qiang WANG Long HUANG Gang-Hai TAN fei Faculty of Engineering China University of GeosciencesWuhan 430074China Shanghai Construction No.4(Group)Co. Ltd.Shanghai 201103China Economic and Technology Research Institute State Grid Shandong Electric Power CompanyJinan 250013China School of Civil Engineering Central South UniversityChangsha 410083China

The computational efficiency of the traditional serial spherical discontinuous deformation analysis(SDDA) program has limited its application in geotechnical engineering problems that need a large number of spheres. The cloud computing technology is used to parallel the SDDA program for the first time in this research. The most computationally intensive portions of the SDDA program, i.e., contact detection and matrix solution, are parallelized with proposed algorithms. The accuracy of the cloud-based parallel SDDA program(CB-PSDDA) is verified first. Further efficiency tests show that significant speedup can be obtained with an 8-server configuration and the computing scale can be up to several tens of thousands of particles. The cloud-based parallelized SDDA program increases its potential in applications of deformation and failure analysis of large-scale and realistic geotechnical engineering problems.

关键词： spherical discontinuous deformation analysis(SDDA) distributed computing cloud computing

An improved three-dimensional spherical DDA model for simulating rock failure

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Science China(Technological Sciences) 2015年第9期58卷 1533-1541页

作者： JIAO YuYong HUANG GangHai ZHAO ZhiYe zheng fei WANG Long State Key Laboratory of Geomechanics and Geotechnical Engineering Institute of Rock and Soil Mechanics Chinese Academy of Sciences School of Civil and Environmental Engineering Nanyang Technological University

In this paper, a discontinuous numerical model, namely SDDARF3D(three-dimensional spherical discontinuous deformation analysis for rock failure), is proposed for simulating the whole process of rock failure. Firstly, within the framework of the classical discontinuous deformation analysis(DDA) method, the formulation of three-dimensional spherical DDA(3D SDDA) is deduced; secondly, a bonding and cracking algorithm is constructed and the SDDARF3 D model is proposed; thirdly, corresponding VC++ calculation code is developed and some verification examples are calculated. The simulated results can intuitively reproduce the failure phenomena of rock mass, indicating that the proposed SDDARF3 D numerical model is correct and effective.

关键词： rock failure three-dimensional spherical discontinuous deformation analysis crack propagation bonding and cracking algorithm

Effect of Decadal Changes in Air-Sea Interaction on the Climate Mean State over the Tropical Pacific

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Atmospheric and Oceanic Science Letters 2014年第5期7卷 400-405页

作者： FANG Xiang-Hui zheng fei International Center for Climate and Environment Science (ICCES) Institute of Atmospheric Physics Chinese Academy of Sciences University of Chinese Academy of Sciences

Collaboration of interannual variabilities and the climate mean state determines the type of E1 Nifio. Recent studies highlight the impact of a La Nifia-like mean state change, which acts to suppress the convection and low-level convergence over the central Pacific, on the predominance of central Pacific （CP） E1 Nifio in the most recent decade. However, how interannual variabilities affect the climate mean state has been less thoroughly investigated. Using a linear shallow-water model, the ef- fect of decadal changes of air-sea interaction on the two types of El Nifio and the climate mean state over the tropical Pacific is examined. It is demonstrated that the predominance of the eastem Pacific （EP） and CP E1 Nino is dominated mainly by relationships between anomalous wind stresses and sea surface temperature （SST）. Furthermore, changes between air-sea interactions from 1980-98 to 1999-2011 prompted the generation of the La Ninalike pattern, which is similar to the background change in the most recent decade.

关键词： air-sea interaction EP E1 Nifio CP E1 Nifio,La Nina-like mean state change

Sea surface temperature anomaly in the tropical North Atlantic during El Nino decaying years

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Atmospheric and Oceanic Science Letters 2021年第6期14卷 14-19页

作者： Xinyu Duan Feng Xue fei zheng International Center for Climate and Environment Sciences Institute of Atmospheric PhysicsChinese Academy of SciencesBeijingChina Climate Center of Meteorological Bureau of Gansu Province LanzhouChina

Based on reanalysis data from 1979 to 2016,this study focuses on the sea surface temperature(SST)anomaly of the tropical North Atlantic(TNA)in El Nino decaying *** TNA SST exhibits a clear warm trend during this *** composite result for 10 El Nino events shows that the TNA SST anomaly reaches its maximum in spring after the peak of an El Nino event and persists until *** general,the anomaly is associated with three factors-namely,El Nino,the North Atlantic Oscillation(NAO),and a long-term trend,leading to an increase in local SST up to 0.4℃,0.3℃,and 0.35℃,respectively.A comparison between 1983 and 2005 indicates that the TNA SST in spring is affected by El Niño,as well as the local SST in the preceding winter,which may involve a long-term trend *** addition,the lead-lag correlation shows that the NAO leads the TNA SST by 2-3 *** comparing two years with an opposite phase of the NAO in winter(i.e.,1992 and 2010),the authors further demonstrate that the NAO is another important factor in regulating the TNA SST anomaly.A negative phase of the NAO in winter will reinforce the El Nino forcing substantially,and vise *** other words,the TNA SST anomaly in the decaying years is more evident if the NAO is negative with El ***,the combined effects of El Nino and the NAO must be considered in order to fully understand the TNA SST variability along with a long-term trend.

关键词： Tropical North Atlantic Sea surface temperature anomaly North Atlantic Oscillation El Nino

The climatology and interannual variability of the East Asian summer monsoonsimulated by a weakly coupled data assimilation system

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Atmospheric and Oceanic Science Letters 2019年第2期12卷 140-146页

作者： LIN Renping zheng fei DONG Xiao International Center for Climate and Environment Sciences Institute of Atmospheric Physics Chinese Academy of Sciences

With the motivation to improve the simulation of the East Asian summer monsoon(EASM) in coupled climate models, oceanic data assimilation(DA) was used in CAS-ESM-C(Chinese Academy of Sciences–Earth System Model–Climate Component) in this study. Observed sea surface temperature was assimilated into CAS-ESM-C. The climatology and interannual variability of the EASM simulated in CAS-ESM-C with DA were compared with a traditional AMIP-type *** showed that the climatological spatial pattern and annual cycle of precipitation in the western North Paci?c, and the ENSO-related and EASM-related EASM circulation and precipitation, were largely improved. As shown in this study, air–sea coupling is important for EASM simulation. In addition, oceanic DA synchronizes the coupled model with the real world without breaking the air–sea coupling process. These two successful factors make the assimilation experiment a more reasonable experimental design than traditional AMIP-type simulations.

关键词： Ocean data assimilation coupled model East Asian summer monsoon AMIP

ENSO combination mode and its influence on seasonal precipitation over southern China simulated by ECHAM5/MPI-OM

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Atmospheric and Oceanic Science Letters 2019年第3期12卷 184-191页

作者： YI Shengjie zheng fei LUO Hao International Center for Climate and Environment Science Institute of Atmospheric PhysicsChinese Academy of SciencesBeijingChina College of Earth and Planetary Sciences University of Chinese Academy of SciencesBeijingChina Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters Nanjing University of Information Science and TechnologyNanjingChina

Recent studies show that a combination mode (C-mode) represents the seasonally modulated dynamics of ENSO, which plays an important role in maintaining the western North Pacific anomalous anticyclone. This C-mode could obviously influence the East Asian climate, especially since the contribution of ENSO to southern China's precipitation has weakened since the late 1990s. This paper evaluates whether the C-mode and its influences on precipitation over southern China can be realistically described by the climate model ECHAM5/MPI-OM. The authors find that the model is able to reproduce the spatial and temporal variability of the C-mode and the asymmetric responses of air-sea variations in the tropical Pacific. The model also reveals the observed significant effects of the C-mode on the wintertime and springtime rainfall over southern China during El Nino events. The findings have implications for ECHAM5/MPI-OM being a valuable tool for simulating and predicting the C-mode-related seasonal precipitation over southern China.

关键词： C-mode precipitation Southern China ECHAM5/MPI-OM

Microstructure Evolution in 9Cr Martensitic Steel During Long-Term Creep at 650℃

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Journal of Iron and Steel Research International 2012年第7期19卷 55-59页

作者： HU zheng-fei WANG Qi-jiang ZHANG Bin School of Material Science and Engineering Tongji University Shanghai 200092 China Institute of Baosteel Shanghai 201900 China

Standardarized creep and rupture strength tests were conducted for commercial T91 martensitic heat-resistant steel at 650℃and corresponding microstructure was characterized by BSED, TEM and EDS. The martensitic microstructure degenerated seriously during creep exposure, including martensitic substructure recovering, carbides coarsening, dissolving and precipitating. EDS analysis shows that the M23C6 carbides in different morphologies have dissimilar compositions. The rod/sheet like M23 C6 particles within the matrix contain more additions, which might precipitate in situ while fine MX particles were re-solving. The high content of silicon in these rod/sheet like M2aC6 carbides is probably related to self diffusion coefficient increasing for the exposed condition at 650 ~C close to Curie temperature To. For those reasons, martensite substructure becomes unstable, and microstructure evolution is accelerated and leads to creep strength deteriorating severely.

关键词： T91 steel creep strength microstructure carbide coarsening self-diffusion