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Factors contributing to rapid decline of Arctic sea ice in autumn

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Advances in Polar Science 2021年第2期32卷 96-104页

作者： LI Shuyao CUI Hongyan XU Junli GONG Xiang QIAO Fangli yang yanzhao WANG Ping HAN Yuqun SHAN Feng College of Mathematics and Physics Qingdao University of Science and TechnologyQingdao 266061China Research Institute for Mathematics and Interdisciplinary Sciences Qingdao University of Science and TechnologyQingdao 266061China Laboratory for Regional Oceanography and Numerical Modeling Qingdao National Laboratory for Marine Science and TechnologyQingdao 266061China The First Institute of Oceanography Ministry of Natural ResourcesQingdao 266061China

Autumn Arctic sea ice has been declining since the beginning of the era of satellite sea ice *** this study,we examined the factors contributing to the decline of autumn sea ice *** the Beaufort Sea to the Barents Sea,autumn sea ice concentration has decreased considerably between 1982 and 2020,and the rates of decline were the highest around the Beaufort *** calculated the correlation coefficients between sea ice extent(SIE)anomalies and anomalies of sea surface temperature(SST),surface air temperature(SAT)and specific humidity(SH).Among these coefficients,the largest absolute value was found in the coefficient between SIE and SAT anomalies for August to October,which has a value of−*** second largest absolute value was found in the coefficient between SIE and SH anomalies for September to November,which has a value of−*** the correlation coefficients between SIE and SST anomalies,the largest absolute value was found in the coefficient for August to October,which has a value of−*** conducted empirical orthogonal function(EOF)analyses of sea ice,SST,SAT,SH,sea level pressure(SLP)and the wind field for the months where the absolute values of the correlation coefficient were the *** first EOFs of SST,SAT and SH account for 39.07%,63.54%and 47.60%of the total variances,respectively,and are mainly concentrated in the area between the Beaufort Sea and the East Siberian *** corresponding principal component time series also indicate positive *** first EOF of SLP explains 41.57%of the total *** is mostly negative in the central *** the Beaufort,Chukchi and East Siberian seas,the zonal wind weakened while the meridional wind *** from the correlation and EOF analyses further verified the effects of the ice-temperature,ice-SH and ice-SLP feedback mechanisms in the *** mechanisms accelerate melting and decrease the rate of formation of sea *** addition,stronger m

关键词： Arctic sea ice rapid decline empirical orthogonal function feedback mechanisms

The past, present, and future of population geography in China：Progress, challenges and opportunities

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Journal of Geographical Sciences 2017年第8期27卷 925-942页

作者： FENG Zhiming LI Fangzhou yang yanzhao LI Peng Institute of Geographic Sciences and Natural Resources Research CAS Beijing 100101 China College of Resources and Environment University of Chinese Academy of Sciences Beijing 100049 China Collaborative Innovation Center for Geopolitical Setting of Southwest China and Borderland Development Kunming 650500 China University of Chinese Academy of Sciences Beijing 100049 China

Population geography （PopGeo）, although a sub-discipline of human geography, should have been well developed in China in light of its national population size and unique demographic issues, regional socio-economic development, and biophysical differences. Yet it typically lags behind the development of its parent disciplines, especially demography and geography. Specifically, PopGeo in Chinese higher education is still at a low level in terms of the three major aspects of disciplinary development： academic majors for higher education, academic conferences, and journals. The research content of PopGeo in China has focused on the growth, composition, change, distribution, and carrying capacity of population at the meso- and macro-spatial scales. As the most populated country in the world, questions about how and why the population changes, where the population settles and migrates to, its maximum carrying capacity, and how to guide sound development of population matter to society and the economy, are always important topics in the PopGeo studies in China. In contrast, some new population phenomena such as human space-time behaviors （commuting, remittances, and friends＇ interaction）, popular in the scientific community abroad, are not fully investigated at the micro-level. Presently, PopGeo in China may face both challenges and opportunities because of the adjustment of fertility policies and implementation of na- tional new urbanization plans at the national level. It is this occasion that calls for a state-of-the-art review of the development of PopGeo since the 1980s, the turning point of an increasing number of PopGeo studies in China. We aim to reveal the current status of Pop- Geo in China to the world, and shed light on its further study.

关键词： population geography fertility policies adjustment population aging new urbanization China

台阵网格自动定位方法在鄂尔多斯地块南部和秦岭-大别造山带的应用

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北京大学学报（自然科学版） 2022年第4期58卷 626-634页

作者：杨延昭盖增喜北京大学地球与空间科学学院北京100871 河北红山地球物理国家野外科学观测研究站邢台054000

利用新近发展起来的台阵网格自动事件定位方法,对鄂尔多斯地块及秦岭-大别造山带区域136个宽频带流动台站记录的连续波形进行扫描和定位。通过与地震目录的对比发现,不仅在常规地震带上分布着大量的事件,而且在地震目录中极少发生地震... 详细信息

利用新近发展起来的台阵网格自动事件定位方法,对鄂尔多斯地块及秦岭-大别造山带区域136个宽频带流动台站记录的连续波形进行扫描和定位。通过与地震目录的对比发现,不仅在常规地震带上分布着大量的事件,而且在地震目录中极少发生地震的区域出现大量地震事件集中分布的现象。这些事件主要分布于鄂尔多斯地块南部以及秦岭-大别造山带附近的断层带。经过对定位台站的抽样分析和对定位事件地震波形的仔细人工确认,验证了这些被扫描并定位的事件的真实性。通过慢度分析,获得所定位事件的面波传播视速度,绝大部分事件对应的视速度在2.5~5.2km/s之间,与地震面波群速度相符。所定位的地震事件可用于补充秦岭-大别造山带的地震目录,同时可以通过进一步的波形拟合来分析其震源机制。

关键词：识别和定位面波地震目录事件分布视速度

Tunable compact asynchronous optical sampling system using Er-doped fiber laser

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High Power Laser Science and Engineering 2023年第2期11卷 110-116页

作者： Zilin Zhao Daping Luo yang Liu Zejiang Deng Lian Zhou Gehui Xie Chenglin Gu yanzhao yang BinWu Wenxue Li State Key Laboratory of Precision Spectroscopy East China Normal UniversityShanghaiChina The 41st Institute of China Electronics Technology Group Corporation QingdaoChina

We report a compact,tunable,self-starting,all-fiber laser-based asynchronous optical sampling(ASOPS)*** Er-doped fiber oscillators were used as the pulsed-laser source,whose repetition rate could be set at 100 MHz with a tuning range of 1.25 MHz through a fiber delay *** employing phase-locked and temperature control loops,the repetition rate offset of the two lasers was stabilized with 7.13×10^(−11)fractional instability at an average time of 1 *** capabilities in the terahertz regime were demonstrated by terahertz time-domain spectroscopy,achieving a spectral bandwidth of 3 THz with a dynamic range of 30 *** large range of repetition rate adjustment in our ASOPS system has the potential to be a powerful tool in the terahertz regime.

关键词： asynchronous optical sampling mode-locked fiber laser terahertz time-domain spectroscopy

Modeling and Performance Analysis of UAV-Aided Millimeter Wave Cellular Networks with Stochastic Geometry

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China Communications 2024年第6期21卷 146-162页

作者： Li Junruo Wang Yuanjie Cui Qimei Hou yanzhao Tao Xiaofeng National Engineering Laboratory for Mobile Network Technologies Beijing University of Posts and TelecommunicationsBeijing 100876China National Computer Network Emergency Response Technical Team/Coordination Center of China(CNCERT/CC) Beijing 100029China Department of Broadband Communication Peng Cheng LaboratoryShenzhen 518055China

UAV-aided cellular networks,millimeter wave(mm-wave) communications and multi-antenna techniques are viewed as promising components of the solution for beyond-5G(B5G) and even 6G *** leveraging the power of stochastic geometry,this paper aims at providing an effective framework for modeling and analyzing a UAV-aided heterogeneous cellular network,where the terrestrial base stations(TBSs) and the UAV base stations(UBSs) coexist,and the UBSs are provided with mm-wave and multi-antenna *** modeling the TBSs as a PPP and the UBSs as a Matern hard-core point process of type Ⅱ(MPH-Ⅱ),approximated but accurate analytical results for the average rate of the typical user of both tiers are derived through an approximation method based on the mean interference-to-signal ratio(MISR) *** influence of some relevant parameters is discussed in detail,and some insights into the network deployment and optimization are *** results show that some trade-offs are worthy of being considered,such as the antenna array size,the altitude of the UAVs and the power control factor of the UBSs.

关键词： average rate downlink millimeter wave point process theory SIR stochastic geometry UAVaided cellular networks

Rubber plantation and its relationship with topographical factors in the border region of China, Laos and Myanmar

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Journal of Geographical Sciences 2013年第6期23卷 1019-1040页

作者： LIU xiaona FENG Zhiming JIANG Luguang LI Peng LIAO Chenhua yang yanzhao YOU Zhen Institute of Geographic Sciences and Natural Resources Research CAS Beijing 100101 China University of Chinese Academy of Sciences Beijing 100049 China

Rubber plantation is the major land use type in Southeast Asia. Monitoring the spa- tial-temporal pattern of rubber plantation is significant for regional land resource development, eco-environmental protection, and maintaining border security. With remote sensing tech- nologies, we analyzed the rubber distribution pattern and spatial-temporal dynamic; with GIS and a newly proposed index of Planted Intensity （PI）, we further quantified the impacts and limits of topographical factors on rubber plantation in the border region of China, Laos and Myanmar （BRCLM） between 1980 and 2010. The results showed that：（1） As the dominant land use type in this border region, the acreage of rubber plantation was 6014 km2 in 2010, accounting for 8.17% of the total area. Viewing from the rubber plantation structure, the ratio of mature- （〉10 year） and young rubber plantation （〈 10 year） was 5：7. （2） From 1980 to 2010, rubber plantation expanded significantly in BRCLM, from 705 km2 to 6014 km2, nearly nine times. The distribution characteristics of rubber plantation varied from concentrated toward dispersed, from border inside to outside, and expanded further in all directions with Jinghong City as the center. （3） Restricted by the topographical factors, more than 4/5 proportion of rubber plantation concentrated in the appropriate elevation gradients between 600 and 1000 m, rarely occurred in elevations beyond 1200 m in BRCLM. Nearly 2/3 of rubber plantation concentrated on slopes of 8^-25~, rarely distributed on slopes above 35~. Rubber plantation was primarily distributed in south and east aspects, relatively few in north and west aspects. Rubber planted intensity displayed the similar distribution trend. （4） Comparative studies of rubber plantation in different countries showed that there was a remarkable increase in area at higher elevations and steeper slopes in China, while there were large appropriate topog- raphical gradients for rubber plantation in Laos and Myanmar which be

关键词： rubber plantation spatial-temporal analysis topographical factors opium poppy substitution planting (OPSP) the border region of China, Laos and Myanmar (BRCLM)

A dynamic analysis of water footprint of Jinghe River basin

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Ecological Economy 2008年第2期4卷 161-171页

作者： Geng Yanhui Min Qingwen Cheng Shengkui Wan Xin yang yanzhao Institute o Geographic Sciences and Natural Resources Research Chinese ACademy of Sciences Beijing 100101P. R China Graduate School Chinese Academy of Sciences Beijing 100039 P. R. China Lanzhou Climate Centet Lanzhou 730020 P. R. China

Water footprint in a region is defined as the volume of water needed for the production of goods and services consumed by the local people, Ecosystem services are a kind of important services, so ecological water use is one necessary component in water footprint. Water footprint is divided into green water footprint and blue water footprint but the former one is often *** this paper waterJootprint includes blue water needed by agricultural irrigation, industrial and domestic water demand, and green water needed by crops, economic forests, livestock prochtcts, forestlalands and grasslands. The study calculates the footprint of the Jinghe River basin in 1990, 1995, 2000 and 2005 with quarto methods. Results of research show that water footprints reached 164.1 ×10^8m3, 175. 69 ×10^8m3 and 178. 45 ×10^8m3 respectively in 1990, 1995 and 2000 including that of ecological water use, but reached 77.68×10^8m3, 94.24×10^8m3, 92.92×10^8m3 and 111.36 ×10^8m3 respectively excluding that of ecological water use. Green *** is much more than blue water footprint; thereby, green water plays an important role in economic development and ecological construction The dynamic change of water footprints shows that blue water use increases rapidly and that the ecological water use is occupied by economie and domestic water use. The change also shows that water use is transferred from primary industry to secondary industry In primary industry, it is transferred from crops farming to forestry, and animal agriculture. The factors impelling the change include development anticipation on econonomy; government policies, readjustment of the industrial structure, population growth, the raise of urbanization level, and structurul change of consumption, low level of waler-saving and poor ability of waste water *** blue water use per unit, green water use per unit, blue water use structure and green water use structure, we analyzed the difference of the six ecologiea

关键词： Water footprint Blue water Green water Dynamic change Influencing factors Jinghe River basin

Spectral programmable mid-infrared optical parametric oscillator

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Photonics Research 2024年第8期12卷 1593-1603页

作者： JUNRUI LIANG JIANGMING XU yanzhao KE SICHENG LI JUNHONG HE YIDONG GUO yang ZHANG XIAOYA MA JUN YE XIAO LI JINYONG LENG PU ZHOU College of Advanced Disciplinary Studies National University of Defense TechnologyChangsha 410073China Nanhu Laser Laboratory National University of Defense TechnologyChangsha 410073China Hunan Provincial Key Laboratory of High Energy Laser Technology National University of Defense TechnologyChangsha 410073China

A spectral programmable,continuous-wave mid-infrared(MIR)optical parametric oscillator(OPO),enabled by a self-developed high-power spectral tailorable fiber laser,was proposed and *** operating at a singlewavelength,the maximum idler power reached 5.53 W at 3028 nm,with a corresponding pump-to-idler conversion efficiency of 14.7%.The wavelength number switchable output was available from one to *** single idler was tunable in a range of 528 nm(2852–3380 nm).In a dual-wavelength operation,the interval between two idlers could be flexibly tuned for 470 nm(53–523 nm),and the intensity of each channel was *** idler emission was realized,meanwhile exhibiting spectral custom-tailored ***,we balanced the parametric gain through the pre-modulating broadband multi-peak pump spectra,enabling a 10 d B bandwidth adjustment of the idler emission from 20 to 125 *** versatile mid-infrared laser,simultaneously featuring wide tuning,multi-wavelength operation,and broad bandwidth manipulation,has great application potential in composition detection,terahertz generation,and speckle-free imaging.

关键词： pump tuning parametric

Assessment of the Water Resources Carrying Capacity in the Great Dunhuang Region

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Journal of Resources and Ecology 2022年第6期13卷 999-1008页

作者： LANG Tingting yang yanzhao ZHANG Chao LIU Ying Institute of Geographic Sciences and Natural Resources Research Chinese Academy of SciencesBeijing 100101China University of Chinese Academy of Sciences Beijing 100049China Key Laboratory of Carrying Capacity Assessment for Resources and Environment Ministry of Natural ResourcesBeijing 101149China

Water resources carrying capacity(WRCC) is an important index for assessing the coordinated development relationship between population and water resources. The quantitative evaluation of WRCC can provide an important basis for water resource regulation and sustainable economic and social development. Based on the statistical data of cities and counties in the Great Dunhuang Region(GDR), and taking counties as the basic units,this study quantitatively analyzed the WRCC and carrying status of the GDR under different water inflow conditions and policy constraints from 2010 to 2017. The study revealed three main trends.(1) From 2010 to 2017, the WRCC of the GDR increased year by year, from 343700, 315900 and 291100 people to 458700, 415400 and 375600people in normal, dry and extremely dry years, respectively.(2) Under policy constraints, the WRCC of the GDR increased year by year from 309400 people in 2010 to 412400 people in 2017. Based on future estimates, the WRCC of the GDR are expected to be 326600 people in 2020 and 341200 people in 2030.(3) From 2010 to 2017,the water resources carrying index of the GDR was decreasing, and it decreased from 1.05, 1.14 and 1.24 to 0.80,0.88 and 0.97 in normal, dry and extremely dry years, respectively. The carrying status changed from critical overload to balanced. Although the WRCC and the carrying status of the GDR had significantly improved by 2017, the overall upper limit of the carrying capacity is not high. Therefore, efforts should be made to improve the utilization efficiency of water resources in order to maintain the sustainable utilization of water resources in the GDR.

关键词： water resources carrying capacity carrying status the Great Dunhuang Region relationship between population and water resources