基于卡尔曼滤波算法的焦炭价格预测

焦炭价格预测研究具有重要的理论和实践意义,本文利用卡尔曼滤波算法对焦炭价格进行预测研究。建立状态空间模型时,选取焦炭价格作为唯一的状态变量,通过每一时刻变量观测值与预测值形成的新息,不断更新和迭代,以寻求最优估测值。实证分析表明,该算法对焦炭价格的跟踪和预测效果较好。     

用卡尔曼滤波算法预测埃塞俄比亚咖啡价格（英文）

埃塞俄比亚咖啡价格波动很大,因此对国家经济发展的影响不容小视,对咖啡价格进行预测具有理论和实践意义。为了分析咖啡价格波动,我们采用来自埃塞俄比亚商品交易所(ECX)记录的2008年6月25日至2017年1月5日期间咖啡日收盘价数据。在这里,咖啡价格的性质是非平稳的,我们在单个线性状态空间模型上应用卡尔曼滤波算法来预测咖啡价格的最优值,主要通过使用均方根误差(RMSE)来评估用于预测咖啡价格的算法的性能。基于线性状态空间模型和卡尔曼滤波算法,均方根误差(RMSE)为0.000016375,说明该算法性能良好,研究结果可靠。     

基于Maxent模型的西藏藏波罗花潜在地理分布预测（英文）

藏波罗花Incarvillea younghusbandii是著名的藏药之一,极具开发和研究价值,但准确预测其潜在地理分布一直是目前尚未解决的关键问题。本文结合实地调查与现有研究数据,以气候和地表覆盖为环境变量,利用Maxent模型与GIS工具,对藏波罗花在西藏地区的潜在地理分布进行预测。研究结果表明:(1)Maxent模型对藏波罗花的潜在地理分布具有较高的预测精度,ROC曲线下面积(Area under the curve,AUC),训练AUC值可达0.994,测试AUC值可达0.996;(2)土壤类型、年降水量和生长繁育期降水量是影响藏波罗花生长分布的最重要环境因子;(3)藏波罗花在西藏有广泛的适生性,雅鲁藏布江与多雄藏布河间的山谷地带、喜马拉雅山脉中段地带河谷区和喜马拉雅山东段北侧与雅鲁藏布江中游南岸相间地带是目前主要的适生区,而喜马拉雅山脉东部部分地区可能会成为藏波罗花的扩散分布区。     

使用跳跃扩散模型的咖啡价格期权定价（英文）

这篇文章旨在构建一个期权定价模型以减少与埃塞俄比亚咖啡价格波动相关的风险。我们使用从埃塞俄比亚商品交易所(ECX)获得的2011年5月31日至2018年3月30日期间记录的埃塞俄比亚每日(WSDA3)咖啡价格来分析其咖啡价格的波动。本文使用跳跃扩散模型对咖啡价格进行建模和期权定价,应用最大似然法估计模型参数,使用均方根误差(RMSE)来对模型进行验证。结果表明Merton和双指数跳跃扩散模型的RMSE值分别为0.1093和0.0783,模型模拟结果与实际数据非常吻合,说明采用蒙特卡罗技术得到的WSDA3价格来对期权定价时,双指数跳跃扩散模型比Merton模型更为有效。     

中国航空运输的时空格局演变与发展预测（英文）

This paper analyses the features and dynamic changes of the spatial layout of air transportation utilization among different provinces in China. It makes use of data for the airport throughput and socio-economic development of every province throughout the country in the years 2006 and 2015, and employs airport passenger and cargo throughput per capita and per unit of GDP as measures of regional air transportation utilization, which is significant for refining indicators of regional air transportation scale and comparing against them. It also analyzes the spatial differences of coupling between the regional air transportation utilization indicators and the key influencing factors on regional air transportation demand and utilization, which include per capita GDP, urbanization rate, and population density. Based on these key influencing factors, it establishes a multiple linear regression model to conduct forecasting of each province's future airport passenger and cargo throughput as well as throughput growth rates. The findings of the study are as follows:(1) Between 2006 and 2015, every province throughout the country showed a trend of year on year growth in their airport passenger and cargo throughput per capita. Throughput per capita grew fastest in Hebei, with a rise of 780%, and slowest in Beijing, with a rise of 38%. Throughput per capita was relatively high in western and southeastern coastal regions, and relatively low in northern and central regions. Airport passenger and cargo throughput per unit of GDP showed growth in provinces with relatively slow economic development, and showed negative growth in provinces with relatively rapid economic development. Throughput per unit of GDP grew fastest in Hebei, rising 265% between 2006 and 2015, and Hunan had the fastest negative growth, with a fall of 44% in the same period. Southwestern regions had relatively high throughput per unit of GDP, while in central, northern, and northeastern regions it was relatively low.(2) Strong correlation exists between airport passenger and cargo throughput per capita and per capita GDP, urbanization rate, and population density. Throughput per capita has positive correlation with per capita GDP and urbanization rate in all regions, and positive correlation with population density in most regions. Meanwhile, there is weak correlation between airport passenger and cargo throughput per unit of GDP and per capita GDP, urbanization rate, and population density, with positive correlation in some regions and negative correlation in others.(3) Between 2015 and 2025, it is estimated that all provinces experience a trend of rapid growth in their airport passenger and cargo throughput. Inner Mongolia and Hebei will see the fastest growth, rising221% and 155%, respectively, while Yunnan, Sichuan, and Hubei will see the slowest growth, with increases of 62%, 63%, and 65%, respectively.     

基于残差自回归与Kalman滤波的天然气消费量组合预测研究（英文）

目前中国以化石能源为主的能源消费格局正逐步优化,清洁能源的消费规模逐步增加。对天然气消费量的预测分析对未来能源消费结构调整具有积极意义。本文创新性地采用拟合值偏离度倒数法进行权重设置,利用残差自回归模型和Kalman滤波算法构建组合预测模型,以《BP世界能源统计年鉴》和《中国统计年鉴》1980–2017年的天然气消费历史数据为对象,对中国天然气消费量进行预测研究。研究结果表明:(1)组合预测模型的预测精度更高:残差自回归预测模型的相对误差落在(–0.08,0.09)区间内,卡尔曼滤波预测的相对误差落在(–0.09, 0.32)区间内,组合预测模型相对误差落在(–0.03, 0.11)区间内。(2)组合预测模型预测结果的稳定性更好:残差自回归预测模型相对误差的预测方差为0.002,卡尔曼滤波预测相对误差的预测方差为0.007,组合预测模型相对误差的预测方差为0.001。(3)其他条件不变的情况下,2018年天然气消费量费预测值为2418.08亿m~3。与其他时间序列预测方法相比,利用残差自回归模型和卡尔曼滤波算法构成的组合预测模型对数据限制条件少,可操作性强,且分析结果更为可信。     

基于水土资源的海南省人口承载力研究（英文）

近年来,海南省海口市、三亚市等地人口快速增长,引起了各界对海南省承载力的担忧,需要研究制定承载力约束和经济增长需求下的人口与资源环境政策。为此,本文选取粮食产量、农产品营养成分和水资源量指标,分别定量测算承载力;采用就业弹性系数法,设定就业弹性系数和地区生产总值增长率,估算经济增长所需人口总量;利用PADIS-INT人口预测软件,设定总生育率、净迁移率等参数,预测人口变化情况。通过研究认为,2050年前海南省人口总量不会超过水土资源的承载力上限,全省总体上不存在人口过多的问题,而是存在人口不足的风险。建议海南省采取鼓励人口增长的政策措施,提升自然资源管理和国土空间治理水平,引导人口在全省均衡发展。     

中国生态交错带（英文）

生态交错带（Ecotone）是指两个群落或两类生态系统之间的过度带,具有脆弱、敏感和易变等特性。20世纪70年代以来,在典型生态系统研究的基础上,生态交错带逐步成为生态学研究的重点。中国地域广阔,地质、气候、植被等生态类型复杂多变,蕴育了不同类型、不同尺度和不同规模的多种生态交错带,不仅为科学研究奠定了广阔空间,而且对我国经济、社会发展,以及文化多样性保护具有重要支撑作用。本文根据我国大尺度下生态交错带的地理分布及其生态环境特点,构建了以土地利用类型、自然气候特征和农业经济发展＂三位一体＂指标体系,并以此为依据对中国典型生态交错带进行了划分和空间分布范围的界定;在此基础上,分别对北方森林草原交错带、北方农牧交错带、西北荒漠绿洲交错带、西南川滇农林牧交错带和东部海陆交错带的动态变化、基本特征和存在问题进行了研究,对全面认识我国生态交错带自然演变规律,促进区域生态环境保护和优化经济发展具有重要意义。     

中国可持续发展研究进展（英文）

Sustainable development has always been a hotspot in Chinese geographical research. Herein, we conduct a systematic statistical analysis of the contribution of Chinese geographers to sustainable development research using bibliometric methods. Based on the review of a vast amount of literature, we identify the main research teams, research funding sources, journals, and key research fields. The findings are as follows:(1) the resources and environmental institutes of the Chinese Academy of Sciences have a significant influence on sustainable development research;(2) China's central government foundations(the National Natural Science Foundation of China and National Social Sciences Fund) are the main research funding sources;(3) most of the highly cited articles are published in journals sponsored by the Geographical Society of China; and(4) sustainable development theory and its research areas are being constantly enriched and perfected. Based on the statistics of keywords, the theory, research methods, research regional scales, and key research areas are summarized and expounded.     

基于文献分析的蓝藻水华爆发成因综述（英文）

在各种水华当中,蓝藻水华发生的范围最广、危害也更大。内陆水体中,蓝藻水华爆发是导致水体富营养化的一大主因,然而其易受气象、水文、人类活动等多种因素的影响,因此研究蓝藻水华爆发的原因成为学者研究的一大重点。该文基于国内外研究现状,首先对2004–2019年间中国知网期刊数据库中143篇相关论文,从文章的关键词进行主题分析,初步获取影响水华爆发因素的关键词分布图,然后利用Python语言编写程序,利用Word Cloud库对这143篇论文全文作词云处理,根据文本中词语出现的频率等参数绘制词云,并剔除无关词项,生成词云图,试图揭示关键词尚未覆盖到的潜在因素。宏观上分析之后,本文又调研了2014–2019年间,中国知网期刊数据库和Web of Science数据库中相关论文,并对检索获取的文献引文进行追溯来补充,分析了领域内的百余篇文章,最终归纳出蓝藻水华爆发的主要原因。研究结果表明水华爆发的因素分为自然因素和人为因素,其中自然因素主要包括光照、水温和营养盐条件,人为因素主要是大型水利工程。该文对这些因素进行了分析总结,并提出相应的综合治理对策,为藻类水华的预防和治理提供了参考,这对水环境的保护有一定的现实意义。     

生态系统脆弱性研究框架:测度、预测及风险评估（英文）

生态系统的健康状况所体现的脆弱性特征,已成为阻碍生态环境可持续发展的关键因素。通过综述国内外学者的相关研究,从生态系统脆弱性的内生逻辑领域出发,整理测量模型、预测方法和风险评估等方面的文献,全面掌握生态系统脆弱性的研究范畴和科学框架,并分析其研究思路及发展趋势。本文得出了以下结论:(1)生态系统脆弱性的内涵既体现自然环境脆弱性的变化,又反映出由于过度开发、工业化生产活动对生态系统造成不可逆的破坏。(2)生态系统脆弱性指标设立应以全面反映其脆弱度的本质特征为目标,包含自然、社会、经济等相关因子的指标体系。(3)生态系统脆弱性测度方法、预测及风险评估的模型种类较多,侧重点及优势各有千秋,应依据研究对象及区域生态系统脆弱性的不同表征及演化机理,采用适宜的方法进行综合、系统性地评价与预测。(4)针对区域系统特点,提出相应的风险管理对策,以及具有针对性的促进生态脆弱区域生态安全和可持续发展的政策建议。     

基于可持续发展目标（SDGs）的“一带一路”农业可持续性分析（英文）

"一带一路"国家需要在顶层谋划方面做出努力,方能确保农业的可持续发展。而这需要对"一带一路"沿线国家农业可持续性有一个准确的评判。本文在"一带一路"可持续农业概念认识与可持续发展目标(SDGs)中农业目标解读的基础上,借助统计回归分析、趋势预测等方法,预测了2030年"一带一路"沿线国家经济增长和城镇化等社会经济发展的趋势,以及这些发展趋势相应地对农业资源环境的冲击。结果表明,"一带一路"沿线国家农业资源环境前景不容乐观,且难以支撑起该地区未来对粮食安全需求的保障,只有采用积极应对政策和措施,并在战略上进行规划和布局,才能确保该地区2030年粮食安全这一农业可持续发展目标的实现。为此,"一带一路"沿线国家需要从构建农业合作平台、设立专项基金,以及创新农业合作模式等三个方面进行战略合作,推动"一带一路"沿线国家的农业实现可持续发展。     

基于潜在植被的拉市海流域生态退化研究（英文）

生态退化是当前世界共同面临的问题,深刻影响着人类的可持续发展。本文以拉市海流域为研究案例,利用Logistic逐步回归模型模拟该区域的潜在植被,并将其作为区域生态退化的参考系统,进而分析该区域的实际退化程度及其分布特征。结果表明：（1）拉市海流域强人类干扰集中在拉市海坝子内,影响因子主要是道路、居民点和耕地;（2）除湖泊外,拉市海存在8种潜在植被类型,其中常绿针叶林为绝对优势群落,其他7种分别是温性草甸、草丛、滩地、常绿阔叶灌木林、落叶阔叶灌木林、温性草原和高寒草原;（3）高程和土壤平均磷含量对多种植被的潜在分布影响显著,不同的植被类型,对于环境因子具有不同的敏感性;（4）整体上,流域生态退化程度较轻,其中未退化区域占比近半数,轻度退化面积约占1/4,中度退化区集中分布在强人类干扰区,占18.64%;重度退化较少发生,面积仅占全流域面积的3.17%。     

基于能值分析的阿富汗可持续性研究（英文）

阿富汗是中国提出的"丝绸之路经济带"和"21世纪海上丝绸之路"("一带一路")的重要国家。由于多年的战乱,阿富汗经济发展相对落后,但其拥有较为丰富的矿产资源和独特的区位优势,对中国的经济战略发展具有深远的意义。为了研究阿富汗生态经济系统的可持续发展状况,本文基于能值分析方法,构建了可持续发展评价指标体系,对阿富汗2008-2015年的能值变化进行了定量评估。结果显示,2008-2015年,阿富汗总能值从5.65×10~(22) sej增长到9.75×10~(22) sej,但不可更新资源能值占总能值使用量之比一直较低,2008年只有1.72%,这表明阿富汗本地资源没有得到有效的开发利用,经济发展非常依赖于外部资源的输入;可持续发展指数(Emergy Sustainability Index,ESI)从3.00下降至0.72,环境负荷率(Environmental Loading Ratio,ELR)从0.77上升至2.06,能值产出率(Emergy Yield Ratio,EYR)从2.31下降至1.49。以上结果表明,阿富汗资源利用不平衡,经济发展水平较低,可持续发展潜力相对较大,急需开展基础建设和合理的资源开发。     

基于第二代测序技术的亚洲象食性分析（英文）

研究大型食草动物的食物组成和偏好,不仅有助于理解大型食草动物在生态系统中发挥的重要作用,而且有助于评估种群的生存能力及其栖息地质量。本研究于旱季（2–4月）在中国云南南滚河国家级自然保护区进行,以确定该地区的一个亚洲象小种群的觅食偏好。通过样线调查和相机陷阱调查,我们观察记录到大象采食了31种植物。通过对野外收集到的亚洲象粪便样本中的rbcL基因进行第二代测序,在象粪样本中共发现90个物种。在所有样本中,科水平上检出率最高的依次为禾本科（Poaceae,47.69%）、桑科（Moraceae,21.25%）和芭蕉科（Musaceae,11.24%）,在物种水平检出率大于1%的只有9种。我们还分析了性别、年龄组和个体之间的食物组成是否存在差异,结果发现,只在个体之间存在显著差异。这项研究为亚洲象的觅食偏好提供了有价值的见解,有助于进一步了解自然保护区内大象与其栖息地之间的相互作用,并为该地区和国内其他亚洲象分布区的物种保护管理决策提供科技支撑。研究建议,生境恢复和食物源基地建设项目可考虑种植本研究发现的9种丰度较高的核心植物种类,不建议在食物源基地建设中选择大象喜食的农作物,应考虑将种植...     

基于水文模型的蒸散发数据同化研究进展（英文）

Accurate estimation of evapotranspiration(ET),especially at the regional scale,is an extensively investigated topic in the field of water science. The ability to obtain a continuous time series of highly precise ET values is necessary for improving our knowledge of fundamental hydrological processes and for addressing various problems regarding the use of water. This objective can be achieved by means of ET data assimilation based on hydrological modeling. In this paper,a comprehensive review of ET data assimilation based on hydrological modeling is provided. The difficulties and bottlenecks of using ET,being a non-state variable,to construct data assimilation relationships are elaborated upon,with a discussion and analysis of the feasibility of assimilating ET into various hydrological models. Based on this,a new easy-to-operate ET assimilation scheme that includes a water circulation physical mechanism is proposed. The scheme was developed with an improved data assimilation system that uses a distributed time-variant gain model(DTVGM),and the ET-soil humidity nonlinear time response relationship of this model. Moreover,the ET mechanism in the DTVGM was improved to perfect the ET data assimilation system. The new scheme may provide the best spatial and temporal characteristics for hydrological states,and may be referenced for accurate estimation of regional evapotranspiration.     

基于WEQ方法的蒙古土壤风蚀空间评价（英文）

Wind erosion is a major contributor to land degradation and desertification. According to the Global Assessment of Human Induced Soil Degradation, the dryland territories of Mongolia are significantly affected by wind erosion. We used the wind erosion equation model in an Arc GIS environment to evaluate wind erosion across Mongolia. The individual factors of the wind erosion equation were parameterized using the following datasets:(a) monthly climatic data from 45 meteorological stations;(b) 16-day composites of MODIS Normalized Difference Vegetation Index data;(c) a SRTM DEM with a 90 m spatial resolution; and(d) the soil map of Mongolia. The results revealed the significant influence of aridity on wind erosion. The desert and semi-desert ecosystems were more vulnerable to wind erosion, hence more affected. The map of wind erosion revealed three major wind erosion regions where the maximum soil loss of 15–27 t/(hm~2·a) was observed. In general, the wind erosion potentials for the entire country of Mongolia are 15–27 t/(hm~2·a) in the deserts and semi-deserts, 10–15 t/(hm~2·a) in the dry steppes and 5–10 t/(hm~2·a) in the steppe regions.     

基于地理探测器的中国陆地热带北界探讨（英文）

The influence of monsoon climatic characteristics makes the tropics of China different from those of other parts of the world. Therefore, the location of the northern boundary of China's tropical zone has been one of the most controversial issues in the study of comprehensive physical regionalisation in China. This paper introduces developments in the study of the northern boundary of China's tropical zone, in which different scholars delimit the boundary with great differences based on different regionalisation objectives, indexes, and methods. The main divergence of opinion is found in different understandings of zonal vegetation, agricultural vegetation type, cropping systems, tropical soil type and tropical characteristics. In this study, we applied the Geo Detector model, which measures the spatial stratified heterogeneity, to validate the northern boundaries of the tropical zone delimited by six principal scholars. The results show that the mean q-statistic value of the higher latitude boundary delimited by Ren Mei'e is the largest(q=0.37), suggesting that, of the rival views, it best reflects the regional differences between China's tropical and subtropical zones, but it is not necessarily suitable for guiding the development of tropical agriculture. The mean values of the q-statistics of Zheng Du's line and Yu Xianfang's line around the Leizhou Peninsula at a lower latitude were smaller, at 0.10 and 0.08 respectively, indicating that the regional differences were smaller than those of Ren Mei'e's boundary. Against the background of global climate change, the climate itself is changing in fluctuation. It is, thus, worth our further research whether the northern boundary of the tropical zone should not be a fixed line but rather should fluctuate within a certain scope to reflect these changes.     

基于Geo-SOM方法的土壤环境调查数据库探索性分析（英文）

A model integrating geo-information and self-organizing map(SOM) for exploring the database of soil environmental surveys was established. The dataset of 5 heavy metals(As, Cd, Cr, Hg, and Pb) was built by the regular grid sampling in Hechi, Guangxi Zhuang Autonomous Region in southern China. Auxiliary datasets were collected throughout the study area to help interpret the potential causes of pollution. The main findings are as follows:(1) Soil samples of 5 elements exhibited strong variation and high skewness. High pollution risk existed in the case study area, especially Hg and Cd.(2) As and Pb had a similar topological distribution pattern, meaning they behaved similarly in the soil environment. Cr had behaviours in soil different from those of the other 4 elements.(3) From the U-matrix of SOM networks, 3 levels of SEQ were identified, and 11 high risk areas of soil heavy metal-contaminated were found throughout the study area, which were basically near rivers,factories, and ore zones.(4) The variations of contamination index(CI) followed the trend of construction land(1.353) forestland(1.267) cropland(1.175) grassland(1.056), which suggest that decision makers should focus more on the problem of soil pollution surrounding industrial and mining enterprises and farmland.