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Soil water and salt distribution under furrow irrigation of saline water with plastic mulch on ridge

Journal of Arid Land 2013年第1期5卷 60-70页

作者： lijuan chen Qi FENG Alxa Desert Ecohydrological Experimental Research Station Cold and Arid Regions Environmental and Engineering ResearchInstitute Chinese Academy of Sciences Lanzhou 730000 China

Furrow irrigation when combined with plastic mulch on ridge is one of the current uppermost wa- ter-saving irrigation technologies for arid regions. The present paper studies the dynamics of soil water-salt trans- portation and its spatial distribution characteristics under irrigation with saline water in a maize field experiment. The mathematical relationships for soil salinity, irrigation amount and water salinity are also established to evaluate the contribution of the irrigation amount and the salinity of saline water to soil salt accumulation. The result showed that irrigation with water of high salinity could effectively increase soil water content, but the increment is limited com- paring with the influence from irrigation amount. The soil water content in furrows was higher than that in ridges at the same soil layers, with increments of 12.87% and 13.70% for MMF9 （the treatment with the highest water salinity and the largest amount of irrigation water） and MMF1 （the treatment with the lowest water salinity and the least amount of irrigation water） on 27 June, respectively. The increment for MMF9 was gradually reduced while that for MMF1 increased along with growth stages, the values for 17 August being 2.40% and 19.92%, respectively. Soil water content in the ridge for MMF9 reduced gradually from the surface layer to deeper layers while the surface soil water content for MMF1 was smaller than the contents below 20 cm at the early growing stage. Soil salinities for the treatments with the same amount of irrigation water but different water salinity increased with the water salinity. When water salinity was 6.04 dS/m, the less water resulted in more salt accumulation in topsoil and less in deep layers. When water salinity was 2.89 dS/m, however, the less water resulted in less salt accumulation in topsoil and salinity remained basically stable in deep layers. The salt accumulation in the ridge surface was much smaller than that in the furrow bottom under this

关键词： water and salt transportation furrow irrigation saline water soil salinity soil water content

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The earth's rotation-dominated seismicity preceding the 2023 M_(W) 7.8 Gaziantep, Türkiye, earthquake

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Geodesy and Geodynamics 2024年第6期15卷 592-601页

作者： Yane Li Xuezhong chen lijuan chen Institute of Geophysics China Earthquake AdministrationBeijing 100081China Chongqing Earthquake Administration Chongqing 401147China

For earthquakes (M≥4.0) occurring along and around the East Anatolian fault zone and the Dead Sea fault zone within ten years immediately before the MW7.8 Gaziantep earthquake,Türkiye,of February 6,2023,we explored the correlation between seismicity and the earth's *** statistically evaluated the correlation using the Schuster's *** results are quantitatively assessed by a *** found a clear downward trend in the p-values from early 2020 to late 2022 in the studied *** also obtained a spatial distribution of the p-values showing a low p-value area near the northeastern end of the aftershock *** the stress induced by the rotation of the earth is very weak,it could control the earthquake occurrence when the focal medium is loaded to the critical state to release a large *** decrease in the b-value in the Gutenberg-Richter (G-R) relation is considered in the form of the tectonic stress increase in the *** investigated the b-value as a function of time in the study *** found that the b-value had decreased for about eleven years before the p-value started to decrease,with a relative reduction of 57%.Therefore,the result of the lower p-values obtained in the present study infers that the earthquakes were dominated by the earth's rotation prior to the MW7.8 Türkiye earthquake due to a critical state of the focal region.

关键词： Earth's rotation M_(W)7.8 Türkiye earthquake p-value b-value

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Extinction in a discrete Lotka-Volterra competitive system with the effect of toxic substances and feedback controls

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International Journal of Biomathematics 2015年第1期8卷 149-161页

作者： lijuan chen Fengde chen College of Mathematics and Computer Science Fuzhou University Fuzhou Fujian 350002 P. R. China

In this paper, we consider a discrete Lotka-Volterra competitive system with the effect of toxic substances and feedback controls. By using the method of discrete Lyapunov function and by developing a new analysis technique, we obtain the sufficient conditions which guarantee that one of the two species will be driven to extinction while the other will be permanent. We improve the corresponding results of Li and chen [Extinction in two-dimensional discrete Lotka Volterra competitive system with the effect of toxic substances, Dynam. Contin. Discrete Impuls. Syst. Ser. B Appl. Algorithms 15 （2008） 165-178]. Also, an example together with their numerical simulations shows the feasibility of our main results. It is shown that toxic substances and feedback control variables play an important role in the dynamics of the system.

关键词： Discrete toxic substances feedback controls permanence extinction

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Preparation and Characterization of Platinum Supported on Carbon Nanotubes with Different Tube Diameter for Cathode Catalysts of Proton Exchange Membrane Fuel Cells

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Journal of Materials Science & Technology 2010年第6期26卷 529-534页

作者： Hong Su Bing Zhang lijuan chen Tecchnical Instituteof Physms and Chemistry of CAS Beijing 100190 China Graduate University of the Chinese Academy of Sciences Beijing 100049 China

Platinum supported on carbon nanotubes （CNTs） with different tube diameters 〈10, 10-20, 40-60 and 60- 100 nm were prepared. The catalysts were characterized by transmission electron microscopy （TEM）, X-ray diffraction （XRD）. The metal particle size for 40 wt pct Pt catalysts were 2-5 nm. Self-prepared Pt/CNTs catalysts and purchased Pt/XC-72 were studied by polarization curves, and it was found that in the H2/O2 fuel cell system, Pt supported on Vulcan XC-72 （Pt/XC-72） possessed higher catalytic activity than Pt/CNTs. But in H2/air system, Pt supported on CNTs with diameter 10-20 nm （Pt/CNTI020） possessed higher activity than other Pt/C catalysts.

关键词： Fuel cell Pt/C catalyst Carbon nanotubes (CNTs) Catalytic activity

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The impact of spatial scale on local Moran's I clustering of annual fishing effort for Dosidicus gigas offshore Peru

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Journal of Oceanology and Limnology 2019年第1期37卷 330-343页

作者： FENG Yongjiu chen lijuan chen Xinjun College of Surveying and Geo-Informatics Tongji University Laboratory for Marine Fisheries Science and Food Production Processes Qingdao National Laboratory for Marine Science and Technology National Distant-water Fisheries Engineering Research Center Shanghai Ocean University Key Laboratory of Sustainable Exploitation of Oceanic Fisheries Resources (Shanghai Ocean University) Ministry of Education School of Earth and Environmental Sciences the University of Queensland Key Laboratory of Ecohydrology of Inland River Basin Northwest Institute of Eco-Environment and Resources Chinese Academy of Sciences

The spatial scale(?shing grid) of ?sheries research af fects the observed spatial patterns of?sheries resources such as catch-per-unit-ef fort(CPUE) and ?shing ef fort. We examined the scale impact of high value(HH) clusters of the annual ?shing ef fort for Dosidicus gigas of fshore Peru from 2009 to *** a multi-scale analysis, the original commercial ?shery data were tessellated to twelve spatial scales from 6′ to 72′ with an interval of 6′. Under these spatial scales, D. gigas clusters were identi?ed using the Anselin Local Moran's I. Statistics including the number of points, mean CPUE, standard deviation(SD),skewness, kurtosis, area and centroid were calculated for these HH clusters. We found that the z-score of global Moran's I and the number of points for HH clusters follow a power law scaling relationship from2009 to 2012. The mean ef fort and its SD also follow a power law scaling relationship from 2009 to *** skewness follows a linear scaling relationship in 2010 and 2011 but ?uctuates with spatial scale in2009 and 2012; kurtosis follows a logarithmic scale relationship in 2009, 2011 and 2012 but a linear scale relationship in 2010. Cluster area follows a power law scaling relationship in 2010 and 2012, a linear scaling relationship in 2009, and a quadratic scaling relationship in 2011. Based on the peaks of Moran's I indices and the multi-scale analysis, we conclude that the optimum scales are 12′ in 2009 ? 2011 and 6′ in 2012, while the coarsest allowable scales are 48′ in 2009, 2010 and 2012, and 60′ in 2011. Our research provides the best spatial scales for conducting spatial analysis of this pelagic species, and provides a better understanding of scaling behavior for the ?shing ef fort of D. gigas in the of fshore Peruvian waters.

关键词： Dosidicus gigas fishing ef fort high-high(HH) cluster scale impact local Moran's I

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Why Is the East Asian Summer Monsoon Extremely Strong in 2018?——Collaborative Effects of SST and Snow Cover Anomalies

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Journal of Meteorological Research 2019年第4期33卷 593-608页

作者： lijuan chen Wei GU Weijing LI Laboratory for Climate Studies National Climate CenterChina Meteorological AdministrationBeijing 100081 Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters Nanjing University of Information Science&TechnologyNanjing 210044

In 2018,summer precipitation was above normal in North and Northwest China and below normal around the Yangtze River valley,due to an extremely strong East Asian summer monsoon(EASM).The atmospheric circulation anomalies in East Asia and key external forcing factors that influence the EASM in 2018 are explored in this *** results show that there existed an anomalous cyclonic circulation near the Philippines,while the western Pacific subtropical high was located more northward than its normal *** the mid–high latitudes,a negative geopotential height anomaly center was found near the Ural Mountains,suppressing the blocking *** such a circulation pattern,precipitation near the Yangtze River valley decreased because local divergence and subsidence intensified,whereas precipitation in northern China increased due to large amounts of water vapor transport by anomalously strong southerly *** analyses reveal that the strong EASM circulation in 2018 might result from the joint influences of several external forcing *** weak La Ni?a event that started from October 2017,the positive North Atlantic Tripolar mode(NAT)in spring 2018,and the reduced snow cover over the Tibetan Plateau in winter 2017/18 all collaboratively contributed to formation of the cyclonic circulation anomaly near the Philippines,leading to the extremely strong ***,the positive NAT and the reduced Tibetan snow cover may have caused the negative geopotential height anomaly near the Ural Mountains,in favor of a strong *** above external factors and their reinforcing impacts on the EASM are further verified by two groups of similar historical cases.

关键词： East Asian summer monsoon external forcing factors La Nina North Atlantic Tripolar mode Indian Ocean basin mode snow cover of the Tibetan Plateau

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Extremely Active Tropical Cyclone Activities over the Western North Pacific and South China Sea in Summer 2018: Joint Effects of Decaying La Nina and Intraseasonal Oscillation

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Journal of Meteorological Research 2019年第4期33卷 609-626页

作者： lijuan chen Zhensong GONG Jie WU Weijing LI Laboratory for Climate Studies National Climate CenterChina Meteorological AdministrationBeijing 100081 Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters Nanjing University of Information Science&TechnologyNanjing 210044

In summer 2018,a total of 18 tropical cyclones(TCs)formed in the western North Pacific(WNP)and South China Sea(SCS),among which 8 TCs landed in China,ranking respectively the second and the first highest since *** of these TCs travelled northwest to northward,bringing in heavy rainfall and strong winds in eastern China and *** present study investigates the impacts of decaying La Nina and intraseasonal oscillation(ISO)on the extremely active TCs over the WNP and SCS in summer 2018 by use of correlation and composite *** is found that the La Nina episode from October 2017 to March 2018 led to above-normal sea surface temperature(SST)over central–western Pacific,lower sea level pressure and 500-hPa geopotential height over WNP,and abnormally strong convective activities over the western Pacific in summer *** preceding oceanic thermal conditions and their effects on circulation anomalies are favorable to TC genesis in *** examination reveals that the monsoon trough was located further north and east,inducing more TCs in northern and eastern WNP;and the more eastward WNP subtropical high as well as the significant wave train with a"-+-+"height anomaly pattern over the midlatitude Eurasia–North Pacific region facilitated the northwest to northward TC *** analyses reveal that two successively active periods of Madden–Julian Oscillation(MJO)occurred in summer 2018 and the boreal summer intraseasonal oscillation(BSISO)was also active over WNP,propagating northward significantly,corresponding to the more northward TC *** MJO was stagnant over the Maritime Continent to western Pacific,leading to notably enhanced convection in the lower troposphere and divergence in the upper troposphere,conducive to TC *** a word,the extremely active TC activities over the WNP and SCS in summer 2018 are closely linked with the decaying La Nina,and the MJO and BSISO;their joint effects result in increased TC occurrences and th

关键词： western North Pacific(WNP) tropical cyclone(TC) La Nina event Madden-Julian Oscillation(MJO) boreal summer intraseasonal oscillation(BSISO)

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Seasonal Prediction Skill and Biases in GloSea5 Relating to the East Asia Winter Monsoon

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Advances in Atmospheric Sciences 2023年第11期40卷 2013-2028页

作者： Daquan ZHANG lijuan chen Gill MMARTIN Zongjian KE China Meteorological Administration Key Laboratory for Climate Prediction Studies National Climate CentreBeijing 100081China Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters(CIC-FEMD) Nanjing University of Information Science&TechnologyNanjing 210044China Met Office Hadley Centre Met OfficeExeter EX13PBUK

The simulation and prediction of the climatology and interannual variability of the East Asia winter monsoon(EAWM),as well as the associated atmospheric circulation,was investigated using the hindcast data from Global Seasonal Forecast System version 5(GloSea5),with a focus on the evolution of model bias among different forecast lead *** GloSea5 reproduces the climatological means of large-scale circulation systems related to the EAWM well,systematic biases exist,including a cold bias for most of China’s mainland,especially for North and Northeast ***5 shows robust skill in predicting the EAWM intensity index two months ahead,which can be attributed to the performance in representing the leading modes of surface air temperature and associated background ***5 realistically reproduces the synergistic effect of El Niño–Southern Oscillation(ENSO)and the Arctic Oscillation(AO)on the EAWM,especially for the western North Pacific anticyclone(WNPAC).Compared with the North Pacific and North America,the representation of circulation anomalies over Eurasia is poor,especially for sea level pressure(SLP),which limits the prediction skill for surface air temperature over East *** representation of SLP anomalies might be associated with the model performance in simulating the interaction between atmospheric circulations and underlying surface conditions.

关键词： East Asia winter monsoon(EAWM) Global Seasonal Forecast System version 5(GloSea5) El Niño–Southern Oscillation(ENSO) prediction skill model bias

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Research on hydraulic wind turbine semi-physical simulation platform

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High Technology Letters 2015年第3期21卷 269-275页

作者：艾超 chen lijuan Kong Xiangdong Liao Lihui chen Wenting Hebei Provincial Key Laboratory of Heavy Machinery Fluid Power Transmission and Control Yanshan University Key Laboratory of Advanced Forging & Forming Technology and Science(Yanshan University) Ministry of Education School of Mechanical Engineering Yanshan University

According to a research on the 30kVA simulation experimental platform of hydraulic wind tur- bine, its basic structure, composition and operation principle are expounded in this paper. An in- verter motor is used to simulate the wind turbine, while a similarity calculation method is applied be- tween the small and large wind turbine. A fixed displacement pump-variable motor closed loop is used as the main transmission system, and a self-excited synchronous generator generates electricity through the grid connection. The experiment and simulation study on the speed and power control of the hydraulic wind turbine is conducted, based on the experimental platform, thus correctness and progressiveness of the experiment platform is further verified. The experimental platform study lays a foundation for further research on the characteristics of hydraulic wind turhln~

关键词： wind power generation hydraulic transmission simulation of experimental platform

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Investigation on variations of apparent stress in the region in and around the rupture volume preceding the occurrence of the 2021 Alaska MW8.2 earthquake

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Earthquake Science 2022年第3期35卷 147-160页

作者： Xuezhong chen Yane Li lijuan chen Institute of Geophysics China Earthquake AdministrationBeijing 100081China Chongqing Earthquake Agency Chongqing 401147China

On July 29, 2021, a large earthquake of MW8.2 occurred south of the Alaska Peninsula. To investigate the spatial-temporal changes of crustal stress in the earthquake-stricken area before this event, we selected 159 earthquakes of 4.7 ≤ MW ≤ 6.9 that occurred in the epicentral region and its surroundings between January 1980 and June 2021 to study the temporal variation and spatial distribution of their apparent stress. In addition, we analyzed the correlation between seismic activities and Earth’s rotation and explored the seismogenic process of this earthquake. The crustal stress rose from January 2008 to December 2016. This period was followed by a sub-instability stage from January 2017 until the occurrence of the MW8.2 earthquake. The average rate of apparent stress change in the first five years of the stress increase period was roughly 2.3 times that in the last four years. The lateral distribution of the apparent stress shows that the areas with apparent stress greater than 1.0 MPa exhibited an expanding trend during the seismogenic process. The maximum apparent stress was located at the earthquake epicenter during the last four years. The distribution of the apparent stress in the E-W vertical cross section revealed that an apparent stress gap formed around the hypocenter during the first five years of the stress increase period, surrounded by areas of relatively high apparent stress. After the Alaska earthquake, most parts of this gap were filled in by aftershocks. The seismic activities during the sub-instability stage exhibited a significant correlation with Earth’s rotation.

关键词： MW8.2 earthquake in Alaska apparent stress variation characteristics Earth’s rotation correlation.

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