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Temperature variation and abrupt change analysis in the Three-River Headwaters Region during 1961-2010

Journal of Geographical Sciences 2012年第3期22卷 451-469页

作者： Yi Xiangsheng Li Guosheng yin yanyu Chinese Acad Sci Inst Geog Sci & Nat Resources Res Beijing 100101 Peoples R China Chinese Acad Sci Grad Univ Beijing 100049 Peoples R China Beijing Normal Univ Sch Geog Beijing 100875 Peoples R China Beijing Normal Univ Key Lab Reg Geog Beijing 100875 Peoples R China

In this study, a monthly dataset of temperature time series （1961-2010） from 12 meteorological stations across the Three-River Headwater Region of Qinghai Province （THRHR） was used to analyze the climate change. The temperature variation and abrupt change analysis were examined by using moving average, linear regression, Spline interpolation, Mann-Kendall test and so on. Some important conclusions were obtained from this research, which mainly contained four aspects as follows. （1） There were several cold and warm fluctuations for the annual and seasonal average temperature in the THRHR and its three sub-headwater regions, but the temperature in these regions all had an obviously rising trend at the statistical significance level, especially after 2001. The spring, summer, autumn and annual average temperature increased evidently after the 1990s, and the winter average temperature exhibited an obvious upward trend after entering the 21st century. Except the standard value of spring temperature, the annual and seasonal temperature standard value in the THRHR and its three sub-headwater regions increased gradually, and the upward trend for the standard value of winter average temperature indicated significantly. （2） The tendency rate of annual average temperature in the THRHR was 0.36℃ 10a^-1, while the tendency rates in the Yellow River Headwater Region （YERHR）, Lancangjiang River Headwater Region （LARHR） and Yangtze River Headwater Region （YARHR） were 0.37℃ 10a^-1, 0.37℃ 10a^-1 and 0.34℃10a^-1 respectively. The temperature increased significantly in the south of Yushu County and the north of Nangqian County. The rising trends of temperature in winter and autumn were higher than the upward trends in spring and summer. （3） The abrupt changes of annual, summer, autumn and winter average temperature were found in the THRHR, LARHR and YARHR, and were detected for the summer and autumn average temperature in the YERHR. The abrupt changes of annual and summer average tempe

关键词： temperature variation inter-annual change inter-decadal change standard value change abruptchange analysis Three.River Headwaters Region

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Pedotransfer Functions for Estimating Soil Bulk Density:A Case Study in the Three-River Headwater Region of Qinghai Province,China

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Pedosphere 2016年第3期26卷 362-373页

作者： YI Xiangsheng LI Guosheng yin yanyu Agriculture Resource Monitoring Station Chinese Academy of Agricultural Engineering Key Laboratory of Land Surface Pattern and Simulation Institute of Geographical Sciences and Natural Resources ResearchChinese Academy of Sciences Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences

Bulk density(BD) is an important soil physical property and has significant effect on soil water conservation function. Indirect methods, which are called pedotransfer functions(PTFs), have replaced direct measurement and can acquire the missing data of BD during routine soil surveys. In this study, multiple linear regression(MLR) and artificial neuron network(ANN) methods were used to develop PTFs for predicting BD from soil organic carbon(OC), texture and depth in the Three-River Headwater region of Qinghai Province, China. The performances of the developed PTFs were compared with 14 published PTFs using four indexes, the mean error(ME), standard deviation error(SDE), root mean squared error(RMSE) and coefficient of determination(R^2). Results showed that the performances of published PTFs developed using exponential regression were better than those developed using linear regression from OC. Alexander(1980)-B, Alexander(1980)-A and Manrique and Jones(1991)-B PTFs, which had good predictions, could be applied for the soils in the study area. The PTFs developed using MLR(MLR-PTFs) and ANN(ANN-PTFs) had better soil BD predictions than most of published PTFs. The ANN-PTFs had better performances than the MLR-PTFs and their performances could be improved when soil texture and depth were added as predictor variables. The idea of developing PTFs for predicting soil BD in the study area could provide reference for other areas and the results could lay foundation for the estimation of soil water retention and carbon pool.

关键词： alpine soil artificial neural network multiple linear regression organic carbon soil depth soil texture

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Spatio-temporal variation of precipitation in the Three-River Headwater Region from 1961 to 2010

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Journal of Geographical Sciences 2013年第3期23卷 447-464页

作者： YI Xiangsheng LI Guosheng yin yanyu Institute of Geographic Sciences and Natural Resources Research CAS Beijing 100101 China University of Chinese Academy of Sciences Beijing 100049 China

Based on a monthly dataset of precipitation time series （1961-2010） from 12 me- teorological stations across the Three-River Headwater Region （THRHR） of Qinghai Province China, the spatio-temporal variation and abrupt change analysis of precipitation were exam- ined by using moving average, linear regression, spline interpolation, the Mann-Kendall test and so on. Major conclusions were as follows. （1） The long-term annual and seasonal pre- cipitation in the study area indicated an increasing trend with some oscillations during 1961-2010; however, the summer precipitation in the Lantsang （Lancang） River Headwater Region （LARHR）, and the autumn precipitation in the Yangtze River Headwater Region （YERHR） of the THRHR decreased in the same period. （2） The amount of annual precipita- tion in the THRHR and its three sub-headwater regions was greater in the 1980s and 2000s. The springs were fairly wet after the 1970s, while the summers were relatively wet in the 1960s, 1980s and 2000s. In addition, the amount of precipitation in the autumn was greater in the 1970s and 1980s, but it was relatively less for the winter precipitation, except in the 1990s （3） The normal values of spring, summer, winter and annual precipitation in the THRHR and its three sub-headwater regions all increased, but the normal value of summer precipitation in the LARHR had a negative trend and the normal value of winter precipitation declined in general. （4） The spring and winter precipitation increased in most of the THRHR. The summer autumn and annual precipitation increased mainly in the marginal area of the west and north and decreased in the regions of Yushu, Zaduo, Jiuzhi and Banma. （5） The spring and winter precipitation in the THRHR and its three sub-headwater regions showed an abrupt change, except for the spring precipitation in the YARHR. The abrupt changes of spring precipitation were mainly in the late 1980s and early 1990s, while the abrupt changes of winter precipita- tion were primary

关键词： precipitation spatio-temporal variation abrupt change analysis Three-River Headwater Region

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Temporal and spatial changes of residential land in the Yuyang desert region of northern Shaanxi Province in recent 20 years

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Frontiers of Earth Science 2012年第3期6卷 250-260页

作者： Xiangsheng YI yanyu yin Yaojie YUE Laboratory of Regional Geography School of Geography Beijing Normal University Beijing 100875 China Institute of Geographic-Sciences and-Natural Resources Research Chinese Academy of Sciences Beijing 100101 China

It is very important to understand the temporal and spatial changes of residential land for the improvement of human settlement environment. Based on the three TM images of 1986, 1996 and 2005 and other assistant maps, the temporal and spatial characteristics of residential land in the Yuyang desert region of northern Shaanxi Province of China were analyzed by using geographical information System （GIS） and remote sensing （RS） technology. Some important conclusions were obtained, which mainly contained four aspects as follows. 1） The area of residential land in the Yuyang desert region increased 956.07 hm2 in total, and the changes of residential land among the townships were different with four various change trends. The expansion speeds in the Yuyang Township and Qinhe Township were the biggest from 1986 to 1996 and from 1996 to 2005, respectively. The expansion intensities in other townships were below 0.1%, except the Yuyang Township. 2） The number of residential land patches increased 2847, while the average area and perimeter of residential land patches decreased 0.304 hm2 and 60.78 m during 1986-2005, respectively. The residential land patches also displayed four different changes from 1986 to 2005 among the townships. 3） The residential land mainly distributed in the middle of Yuyang Township and Mahe Township, and the interface of Jinjitan Township and Mengjiawan Township. The total spatial pattern of residential land was relative stability, but the significant changes of residential land were found in the Yuyang Township and its vicinities during 1986-2005. 4） Three distribution patterns of residential land at the micro scale were categorized from the 100 typical villages in the study area. The number of villages in the pattern 1 increased, while the pattern 2 and pattern 3 decreased in recent 20 years, which implicated the adaptation of humans to the habitation environment. This research would provide scientific references fbr harmonizing the human-land r

关键词： residential land temporal change spatialpattern Yuyang desert region

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成都大运会期间德阳市臭氧和VOCs污染特征分析

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绿色科技 2024年第4期26卷 179-184页

作者：肖勇杨净尹彦羽王辉四川省德阳生态环境监测中心站四川德阳618000 河北先河环保科技股份有限公司河北石家庄050035

为评估成都大运会期间,德阳市采取管控措施对空气质量的影响,基于常规监测参数、气象因子和在线VOCs数据进行了分析。结果显示,德阳市管控期间,NO_(2)削减率50.0%,PM_(10)和PM_(2.5)削减率分别为45.7%和42.9%,CO和O_(3)-8h削减率分别为2... 详细信息

为评估成都大运会期间,德阳市采取管控措施对空气质量的影响,基于常规监测参数、气象因子和在线VOCs数据进行了分析。结果显示,德阳市管控期间,NO_(2)削减率50.0%,PM_(10)和PM_(2.5)削减率分别为45.7%和42.9%,CO和O_(3)-8h削减率分别为25.0%和20.6%,管控取得了较好的成效,改善了德阳市空气质量。臭氧前体物VOCs浓度39.95×10^(-9),低于管控前后;VOCs解析结果显示德阳市大运会期间对于工艺过程、固定燃烧源和溶剂使用的管控效果较好,较管控前的削减比例均在50%以上,移动源的削减比例约20%,而对于油气挥发,有待采取更为合理的管控措施。

关键词：大学生运动会空气质量 VOCs 源解析管控效果

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Effect of Ni content on the wear behavior of Al-Si-Cu-Mg-Ni/SiC particles composites

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International Journal of Minerals,Metallurgy and Materials 2024年第2期31卷 374-383页

作者： yanyu Liu Lina Jia Wenbo Wang Zuheng Jin Hu Zhang School of Materials Science and Engineering Beihang UniversityBeijing 100191China Ningbo Institute of Technology Beihang UniversityNingbo 315100China Qingdao Research Institute of Beihang University Qingdao 266000China Research Institute for Frontier Science Beihang UniversityBeijing 100191China

In recent years,the addition of Ni has been widely acknowledged to be capable of enhancing the mechanical properties of Al-Si ***,the effect of Ni on the wear behaviors of Al-Si alloys and Al matrix composites,particularly at elevated temperat-ures,remains an understudied *** this study,Al-Si-Cu-Mg-Ni/20wt%SiC particles(SiCp)composites with varying Ni contents were prepared by using a semisolid stir casting *** effect of Ni content on the dry sliding wear behavior of the prepared compos-ites was investigated through sliding tests at 25 and 350℃.Results indicated that theθ-Al_(2)Cu phase gradually diminished and eventually disappeared as the Ni content increased from 0wt%to 3wt%.This change was accompanied by the formation and increase inδ-Al_(3)CuNi andε-Al_(3)Ni phases in *** hardness and ultimate tensile strength of the as-cast composites improved,and the wear rates of the composites decreased from 5.29×10^(−4)to 1.94×10^(−4)mm^(3)/(N∙m)at 25℃and from 20.2×10^(−4)to 7×10^(−4)mm^(3)/(N∙m)at 350℃with the increase in Ni content from 0wt%to 2wt%.The enhancement in performance was due to the presence of strengthening network structures and additional Ni-containing phases in the ***,the wear rate of the 3Ni composite was approximately two times higher than that of the 2Ni composite due to the fracture and debonding of theε-Al_(3)Ni *** wear,delamination wear,and oxidation wear were the predominant wear mechanisms of the investigated composites at 25℃,whereas delamination wear and oxid-ation wear were dominant during sliding at 350℃.

关键词： Al matrix composite microstructure sliding test high temperature wear mechanism

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PRRSV degrades MDA5 via dual autophagy receptors P62 and CCT2 to evade antiviral innate immunity

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Virologica Sinica 2024年第2期39卷 264-276页

作者： Ruiqi Sun yanyu Guo Lilin Zhang Huixia Zhang Boxuan yin Xiaoyang Li Changyan Li Liu Yang Lei Zhang Zexing Li Jinhai Huang School of Life Sciences Tianjin UniversityTianjin300072China

Porcine reproductive and respiratory syndrome virus(PRRSV)is a major economically devastating pathogen that has evolved various strategies to evade innate *** of antiviral interferon largely promotes PRRSV immunoevasion by utilizing cytoplasmic melanoma differentiation-associated gene 5(MDA5),a receptor that senses viral *** this study,the downregulated transcription and expression levels of porcine MDA5 in PRRSV infection were observed,and the detailed mechanisms were *** found that the interaction between P62 and MDA5 is enhanced due to two factors:the phosphorylation modification of the autophagic receptor P62 by the upregulated kinase CK2αand the K63 ubiquitination of porcine MDA5 catalyzed by the E3 ubiquitinase TRIM21 in PRRSV-infected *** a result of these modifications,the classic P62-mediated autophagy is ***,porcine MDA5 interacts with the chaperonin containing TCP1 subunit 2(CCT2),which is enhanced by PRRSV *** interaction promotes the aggregate formation and autophagic clearance of MDA5-CCT2-nsp3 independently of *** summary,enhanced MDA5 degradation occurs in PRRSV infection via two autophagic pathways:the binding of MDA5 with the autophagy receptor P62 and the aggrephagy receptor CCT2,leading to intense innate immune *** research reveals a novel mechanism of immune evasion in PRRSV infection and provides fundamental insights for the development of new vaccines or therapeutic strategies.

关键词： Porcine reproductive and respiratory syndrome virus(PRRSV) nsp3 Autophagy MDA5

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Multi-scale modeling for prediction of mechanical performance in brazed GH99 thin-walled structure

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Chinese Journal of Aeronautics 2024年第7期37卷 550-563页

作者： Yazhou LIU Shengpeng HU yanyu SONG Wei FU Xiaoguo SONG Ning GUO Weimin LONG State Key Laboratory of Advanced Welding and Joining Harbin Institute of TechnologyHarbin 150001China Shandong Institute of Shipbuilding Technology Weihai 264209China China Machinery Intelligent Equipment Innovation Research Institute(Ningbo)Co. Ltd.Ningbo 315700China

Superalloy thin-walled structures are achieved mainly by brazing,but the deformation process of brazed joints is non-uniform,making it a challenging research *** paper records a thorough investigation of the effect of brazing parameters on the microstructure of joints and its mechanical properties,which mainly inquires into the deformation and fracture mechanisms in the shearing process of GH99/BNi-5a/GH99 *** macroscopic-microscopic deformation mechanism of the brazing interface during shearing was studied by Crystal Plasticity(CP)and Molecular Dynamics(MD)on the basis of the optimal brazing *** experimental results show that the brazing interface is mainly formed by(Ni,Cr,Co)(s,s)and possesses a shear strength of approximately 546 *** shearing fracture of the brazed joint occurs along the brazing seam,displaying the characteristics of intergranular *** simulations show that dislocations disassociate and transform into fine twinning with increased *** simulated the shear deformation process of the brazed *** multiscale simulation results are consistent with the experimental *** mechanical properties of thin-walled materials for brazing are predicted using MD and CP methods.

关键词： Multi-scale modeling Brazing Shear mechanisms Crystal plasticity GH99 superalloy

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Charge Accumulation Characteristics of SF6-Epoxy Interface Under Negative Repetitive Nanosecond Pulses

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CSEE Journal of Power and Energy Systems 2024年第4期10卷 1808-1815页

作者： Shaocong Wu Geng Chen Yuming Shao Hao Xu Xuanning Zhang yanyu Liang Youping Tu State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources and the Beijing Key Laboratory of High Voltage and EMC North China Electric Power UniversityBeijing 102206China

Repetitve nanosecond impulses in gas-insulated metal-enclosed switchgear (GIS) are likely to trigger inside flashover. Interface charges on the spacer in GIS are considered one of the main factors damaging insulation performance and may be induced by overvoltage. For good understanding of insulation failures, accumulation characteristics of charges between SF6 and epoxy spacers under repetitive nanosecond impulses are investigated. It can be found under nanosecond impulses, the charge source in gas volume contributes to interface charge accumulation predominantly. Interface charges will be promoted by impulse number and amplitude. Accumulation processes are analyzed based on runaway electrons mechanism. When impulse amplitude exceeds a threshold value, discharge in the gas volume turns to a runaway mode. A runaway electron leads to the interface charge accumulation. Affected by motion of the runaway electrons, the potential peak gradually moves close to the grounded electrode when impulse amplitude is raised. Meanwhile, increasing impulse number can enhance surface potential. Surface potential will reach saturation eventually. However, memory effect of the repetitive impulse discharge makes the half-peak width of the surface potential at the interface change little. Design of GIS gas-solid insulations can refer to this research.

关键词： GIS interface charge repetitive nano-second pulse SF6

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Electron-beam-driven anomalous Doppler effects in Smith–Purcell radiation

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Photonics Research 2024年第1期12卷 78-84页

作者： XIAOQIUYAN ZHANG TIANYU ZHANG ZHUOCHENG ZHANG XINGXING XU DIWEI LIU ZHAOYUN DUAN yanyu WEI YUBIN GONG LIANG JIE WONG MIN HU Terahertz Research Center School of Electronic Science and EngineeringUniversity of Electronic Science and Technology of ChinaChengdu 610054China Key Laboratory of Terahertz Technology Ministry of EducationChengdu 610054China School of Electrical and Electronic Engineering Nanyang Technological UniversitySingapore 639798Singapore

The interaction between electrons and matter is an effective means of light emission,through mechanisms including Cherenkov radiation and Smith–Purcell radiation(SPR).In this study,we show that the superlight inverse Doppler effects can be realized in reverse Smith–Purcell radiation excited by a free electron beam with a homogeneous *** particular,we find that two types of anomalous SPR exist in the homogenous substrate:special SPR and reverse *** results reveal that the electron velocity can be tuned to simultaneously excite different combinations of normal SPR,special SPR,and reverse *** proposed manifold light radiation mechanism can offer greater versatility in controlling and shaping SPR.

关键词： anomalous beam Electron

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