检索结果-南通市图书馆

Increased sandstorm frequency in North China in 2023:Climate change reflection on the Mongolian plateau

维普期刊数据库博看期刊评论

在线全文

学校读者我要写书评

暂无评论

The Innovation 2023年第5期4卷 15-16页

作者： Jinling Piao Wen Chen Ke Wei Qingyu Cai Xiaowan Zhu zhencai du Center for Monsoon System Research Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100190China Department of Atmospheric Sciences Yunnan UniversityKunming 650500China College of Earth and Planetary Sciences University of Chinese Academy of SciencesBeijing 100049China Bejing Weather Forecast Center Bejing 100089China

There has been a decreasing trend in the average number of days of sandstorms in Beijing over the last 7 decades from±30 days between 1950 and the 1960s to 3-5 days between 2010 and *** main drivers of this trend include weakening wind speed,increasing vegetation cover,and wetter soils of sandstorm source regions in North *** changes can be attributed to various factors,including the ecology compensation project,global warming,and internal atmospheric ***,sandy and dusty conditions occurred in Beijing over 11 days during the first four months of 2023,exceeding the average between 2018 and 2022 of 4 days and negatively impacting the livelihoods of milions of *** recent conditions have raised doubts over the effectiveness of the extensive afforestation *** is a major source of dust in East Asia,and it appears highly likely that extreme climate change over Mongolia played a crucial *** the 11 days of sand and dust weather that occurred over Bejjing in 2023,10 displayed sources that directly originated from Mongolia,with the only exception of the dust backflow case on April 12th(Figure 1).

关键词： China storm plateau

Differences and Links between the East Asian and South Asian Summer Monsoon Systems:Characteristics and Variability

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Advances in Atmospheric Sciences 2017年第10期34卷 1204-1218页

作者： Ronghui HUANG Yong LIU zhencai du Jilong CHEN Jingliang HUANGFU Center for Monsoon System Research Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100190China State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics Institute of Atmospheric PhysicsChinese Academy of ScienceBeijing 100029China Institute of Earth Sciences University of Chinese Academy of SciencesBeijing 100049China

This paper analyzes the differences in the characteristics and spatio–temporal variabilities of summertime rainfall and water vapor transport between the East Asian summer monsoon（EASM） and South Asian summer monsoon（SASM） systems. The results show obvious differences in summertime rainfall characteristics between these two monsoon systems. The summertime rainfall cloud systems of the EASM show a mixed stratiform and cumulus cloud system, while cumulus cloud dominates the SASM. These differences may be caused by differences in the vertical shear of zonal and meridional circulations and the convergence of water vapor transport fluxes. Moreover, the leading modes of the two systems＇ summertime rainfall anomalies also differ in terms of their spatiotemporal features on the interannual and interdecadal timescales. Nevertheless, several close links with respect to the spatiotemporal variabilities of summertime rainfall and water vapor transport exist between the two monsoon systems. The first modes of summertime rainfall in the SASM and EASM regions reveal a significant negative correlation on the interannual and the interdecadal timescales. This close relationship may be linked by a meridional teleconnection in the regressed summertime rainfall anomalies from India to North China through the southeastern part over the Tibetan Plateau, which we refer to as the South Asia/East Asia teleconnection pattern of Asian summer monsoon rainfall. The authors wish to dedicate this paper to Prof. duzheng YE, and commemorate his 100 thanniversary and his great contributions to the development of atmospheric dynamics.

关键词： East Asian summer monsoon South Asian summer monsoon spatiotemporal variability rainfall water vapor transport

Optimization of inter-seasonal nitrogen allocation increases yield and resource-use efficiency in a water-limited wheat-maize cropping system in the North China Plain

在线全文

学校读者我要写书评

暂无评论

The Crop Journal 2024年第3期12卷 907-914页

作者： Xiaonan Zhou Chenghang du Haoran Li zhencai Sun Yifei Chen Zhiqiang Gao Zhigan Zhao Yinghua Zhang Zhimin Wang Ying Liu College of Agronomy and Biotechnology China Agricultural UniversityBeijing 100193China College of Information and Electrical Engineering China Agricultural UniversityBeijing 100193China Ministerial and Provincial Co-Innovation Centre for Endemic Crops Production with High-Quality and Efficiency in Loess Plateau Taigu 030801ShanxiChina

Winter wheat–summer maize cropping system in the North China Plain often experiences droughtinduced yield reduction in the wheat season and rainwater and nitrogen(N)fertilizer losses in the maize *** study aimed to identify an optimal interseasonal water-and N-management strategy to alleviate these *** ratios of allocation of 360 kg N ha^(-1)between the wheat and maize seasons under one-time presowing root-zone irrigation(W0)and additional jointing and anthesis irrigation(W2)in wheat and one irrigation after maize sowing were set as follows:N1(120:240),N2(180:180),N3(240:120)and N4(300:60).The results showed that under W0,the N3 treatment produced the highest annual yield,crop water productivity(WPC),and nitrogen partial factor productivity(PFPN).Increased N allocation in wheat under W0 improved wheat yield without affecting maize yield,as surplus nitrate after wheat harvest was retained in the topsoil layers and available for the subsequent *** W2,annual yield was largest in the N2 *** risk of nitrate leaching increased in W2 when N application rate in wheat exceeded that of the N2 treatment,especially in the wet *** to W2N2,the W0N3 maintained 95.2%grain yield over two *** WPCwas higher in the W0 treatment than in the W2 ***,following limited total N rate,an appropriate fertilizer N transfer from maize to wheat season had the potential of a“triple win”for high annual yield,WPCand PFPN in a water-limited wheat–maize cropping system.

关键词： Cropping system Water-saving irrigation North China Plain Nitrogen optimization Sustainable intensification

A dynamic regulation of nitrogen on floret primordia development in wheat

在线全文

学校读者我要写书评

暂无评论

The Crop Journal 2024年第1期12卷 271-280页

作者： Zhen Zhang Yujing Li Yuxun Wu Xiaoyu Zheng Xiaolei Guo Wan Sun zhencai Sun Zhimin Wang Yinghua Zhang College of Agronomy and Biotechnology China Agricultural UniversityBeijing 100193China College of Biological Sciences China Agricultural UniversityBeijing 100193China Engineering Technology Research Center for Agriculture in Low Plain Areas Cangzhou 061800HebeiChina

Nitrogen(N)fertilization is critical for spike and floret development,which affects the number of fertile florets per spike(NFFs).However,the physiological regulation of the floret development process by N fertilization is largely unknown.A high temporal-resolution investigation of floret primordia number and morphology,dry matter,and N availability was conducted under three N fertilization levels:0(N0),120(N1)and 240(N2)kg ha^(−1).Interestingly,fertile florets at anthesis stage were determined by those floret primordia with meiotic ability at booting stage:meiotic ability was a threshold that predicted whether a floret primordium became fertile or abortive *** the developmental rate of the 4th floret primordium in the central spikelet was accelerated and then they acquired meiotic ability,the NFFs increased gradually as N application increased,but the increase range decreased under *** were no differences in spike N concentration among treatments,but leaf N concentration was increased in the N1 and N2 ***,dry matter accumulation and N content of the leaf and spike in the N1 and N2 treatments was increased as compared to ***,optimal N fertilization increased leaf N availability and transport of assimilates to spikes,and allowed more floret primordia to acquire meiotic ability and become fertile florets,finally increasing *** was no difference in leaf N concentration between N1 and N2 treatment,whereas soil N concentration at 0–60 cm soil layers was higher in N2 than in N1 treatment,implying that there was still some N fertilization that remained ***,improving the leaf’s ability to further use N fertilizer is vital for greater NFFs.

关键词： Fertile florets Floret primordia Grain number Meiotic ability Morphological development

面向碳中和的“一带一路”气候变化主要特征与灾害风险研究

在线全文

学校读者我要写书评

暂无评论

中国科学院院刊 2023年第9期38卷 1371-1386页

作者：张井勇何静张丽霞杜振彩李仁强徐明中国科学院大气物理研究所北京100029 中国科学院地理科学与资源研究所北京100101 中国科学院大学地球与行星科学学院北京100049 中山大学大气科学学院珠海519082

人类社会已广泛认识到,气候变化是全球面临的最重大的风险危机之一。近50年是过去2000年以来“一带一路”地区最暖时期,这主要归因于人类碳排放不断增加和累积。20世纪80年代以来,“一带一路”地区平均气候变化表现为增温速率快、降水... 详细信息

人类社会已广泛认识到,气候变化是全球面临的最重大的风险危机之一。近50年是过去2000年以来“一带一路”地区最暖时期,这主要归因于人类碳排放不断增加和累积。20世纪80年代以来,“一带一路”地区平均气候变化表现为增温速率快、降水和蒸发增加、海平面加速上升等特征,极端高温、暴雨洪涝、干旱等极端天气气候事件总体上频次和强度均快速增加;进入21世纪以来,“一带一路”地区每10年气候灾害发生次数超过20世纪70年代发生次数的5倍。“一带一路”地区近50年气候系统的显著变化主要可归因于人为温室气体排放,同时受到人为气溶胶排放、土地利用与覆盖变化等的影响。预估研究表明,实现全球碳中和前,“一带一路”地区平均与极端气候变化将沿着目前的趋势非线性发展,气候变化灾害风险整体上将呈现不断增加的趋势;碳中和时期,气候变化特征将呈现新格局,气候风险将出现新变化。文章综合分析并识别“一带一路”地区重大气候灾害风险及空间差异性,提出相关防范应对建议。

关键词：气候变化灾害风险一带一路碳中和可持续发展

维普期刊数据库博看期刊

在线全文

学校读者我要写书评

暂无评论

粮食安全背景下保障饲料粮供给的策略研究

中国饲料 2024年第10期 160-163页

作者：吴珍彩河南牧业经济学院经济与贸易学院河南郑州450044

不确定因素的增多致使全球粮食安全形势不容乐观,我国利用外部饲料粮的风险加剧。在饲料粮需求增大、对外依存度上升情况下,如何保障饲料粮供给安全备受关注。其中,玉米大豆带状复合种植,生物育种产业化应用,玉米豆粕减量替代等实施缓... 详细信息

不确定因素的增多致使全球粮食安全形势不容乐观,我国利用外部饲料粮的风险加剧。在饲料粮需求增大、对外依存度上升情况下,如何保障饲料粮供给安全备受关注。其中,玉米大豆带状复合种植,生物育种产业化应用,玉米豆粕减量替代等实施缓解了饲料粮供给压力。为确保效果更好,还需多措并举保障饲料粮供给,以应对严峻的粮食安全形势。

关键词：粮食安全饲料粮供给安全进口多元化

数字经济发展对农产品国际贸易增长的影响——基于空间计量模型的实证检验

在线全文

学校读者我要写书评

暂无评论

商业经济研究 2024年第4期 129-133页

作者：吴珍彩河南牧业经济学院经济与贸易学院河南郑州450044

本研究基于2007-2021年我国31个省份的年度面板数据构建空间计量模型,从空间相关性和空间异质性两个层面探索数字经济发展对农产品国际贸易增长的影响。实证结果表明:数字经济发展不仅能促进当地农产品国际贸易的显著增长,还对周边地区... 详细信息

本研究基于2007-2021年我国31个省份的年度面板数据构建空间计量模型,从空间相关性和空间异质性两个层面探索数字经济发展对农产品国际贸易增长的影响。实证结果表明:数字经济发展不仅能促进当地农产品国际贸易的显著增长,还对周边地区的农产品国际贸易有显著的正向溢出。此外,本研究进一步探讨不同地区数字经济发展对农产品国际贸易增长影响的异质性。基于上述研究结果,为农产品国际贸易的决策提供有力参考。

关键词：农产品国际贸易数字经济发展空间计量模型空间相关性

在线全文

学校读者我要写书评

暂无评论

单绳缠绕式矿井提升机制动瞬态冲击抑制策略

华南理工大学学报（自然科学版） 2024年第3期52卷 141-150页

作者：解辉沈刚刘东汤裕朱真才中国矿业大学机电工程学院江苏徐州221000 安徽理工大学机电工程学院安徽淮南232000 中国船舶集团有限公司第七一三研究所河南郑州450015

在矿井提升机的制动控制中,制动瞬态冲击是影响矿井提升机安全可靠运行的关键问题。由于受到技术和经济成本的制约,目前包含贴闸/压紧的制动过程全程采用力闭环控制,这不可避免地导致闸瓦与闸盘刚性接触时的制动力瞬态冲击问题。针对矿... 详细信息

在矿井提升机的制动控制中,制动瞬态冲击是影响矿井提升机安全可靠运行的关键问题。由于受到技术和经济成本的制约,目前包含贴闸/压紧的制动过程全程采用力闭环控制,这不可避免地导致闸瓦与闸盘刚性接触时的制动力瞬态冲击问题。针对矿井提升机制动瞬态冲击问题,文中提出了一种基于滞回切换原理的混合贴闸/压紧制动控制策略。首先,分别利用非奇异快速终端滑模控制和反步控制设计了贴闸和压紧控制器;其次,为达到快速贴闸的目的,设计了一种基于离散积分器的在线贴闸轨迹再规划方法,有效地减小了制动器贴闸时间;然后,为实现由贴闸控制到压紧控制的安全切换,利用滞回切换原理,制定了混合贴闸/压紧控制稳态切换策略,大大减小了制动力瞬态冲击;最后,为验证提出方法的有效性,选择传统全程力闭环控制策略C1与混合贴闸/压紧直接切换策略C2作为对比方法,在单绳缠绕式提升试验台进行了对比实验,从贴闸时间、制动力最大跟踪误差和提升钢丝绳最大张力3个方面对实验结果进行了分析。实验结果表明:相较于C1控制策略,提出制动控制策略的贴闸时间缩短了64.5%,钢丝绳张力峰值减小了41 N;相较于C2控制策略,提出制动控制策略的制动力冲击减小了90.3%,钢丝绳张力峰值减小了88 N。上述结果表明本文提出的方法能有效改善制动瞬态冲击,减小制动空动时间,提高制动系统安全性,同时本研究也为一类需要混合力/位置控制的电液伺服系统提供了一种有效的解决方法。

关键词：矿井提升机制动系统瞬态冲击非线性控制混合力/位置控制约束轨迹规划

在线全文

学校读者我要写书评

暂无评论

大气科学 2010年第6期34卷 1168-1186页

作者：杜振彩黄荣辉黄刚中国科学院大气物理研究所大气科学和地球流体力学数值模拟国家重点实验室北京100029 中国科学院研究生院北京100049

本文根据政府间气候变化委员会(IPCC)第四次评估报告(AR4)(简称IPCC-AR4)中22个耦合模式对20世纪气候模拟(20C3M)结果中20世纪晚期亚洲夏季风降水的模拟所显示出各模式模拟能力的较大空间差异,提出了一种滑动窗区空间相关系数来量化表... 详细信息

本文根据政府间气候变化委员会(IPCC)第四次评估报告(AR4)(简称IPCC-AR4)中22个耦合模式对20世纪气候模拟(20C3M)结果中20世纪晚期亚洲夏季风降水的模拟所显示出各模式模拟能力的较大空间差异,提出了一种滑动窗区空间相关系数来量化表征这种空间差异特征,结果表明,该系数明显优于传统空间相关系数,其空间分布能够较为细致地描述各模式对较小区域模拟性能的空间差异特征。在此基础上,本文提出以这种滑动窗区空间相关系数作为各模式的权重系数进行加权集合平均,并称之为滑动窗区空间相关系数加权集合方法。利用该方法对IPCC-AR422个耦合模式所模拟的20世纪晚期亚洲夏季风降水进行加权集合平均,并将其结果与传统空间相关系数加权集合平均以及等权重多模式集合平均结果进行比较,表明了利用本文所提出的加权集合方法对20世纪晚期亚洲夏季风降水的集合模拟结果明显优于简单的等权重多模式集合平均结果以及传统空间相关系数加权集合平均结果。鉴于此原因,本文利用此方法对在A1B(各种能源均衡发展)排放情景下IPCC-AR4中22个耦合模式所模拟的21世纪各时期亚洲夏季风降水演变趋势进行集合预测。其结果表明:在A1B排放情景下,从21世纪中期(2045～2065年)开始南亚夏季风降水将比20世纪晚期明显增强;而东亚夏季风降水相对于20世纪晚期的变化呈现出从南到北经向三极子型异常分布特征,即华南和华北地区夏季风降水增多,而长江流域夏季风降水相对于20世纪晚期没有太大变化。并且,结果还表明亚洲夏季风降水异常这种变化趋势可以延续到21世纪晚期。

关键词：滑动窗区空间相关集合方法耦合模式亚洲夏季风降水