Temporal and Spatial Dynamics Analysis of Grassland Ecosystem Pressure in Kazakhstan     

WEN Xin  YAN Huimin  XIE Xiaoping  DU Wengpeng  LAI Chenxi  ZHEN Lin 《资源与生态学报(英文版)》2019,10(6):667-675

Affected by climate change and policy factors, Kazakhstan is the country with the most severe ecological degradation and grassland conflicts in Central Asia. Therefore, studying the state of grassland carrying resources in Kazakhstan is particularly important for understanding the responses of grassland ecosystems to climate change and human activities. Based on Kazakhstan's remote sensing data and animal husbandry statistics, this study analyzes the patterns of changes in grassland ecosystems in Kazakhstan based on the supply and consumption of these ecosystems. The results show that: 1) From 2003 to 2017, the number of livestock raised in Kazakhstan showed a trend of sustained and steady growth. Due to freezing damage, the scale of livestock farming decreased in 2011, but a spatial difference in the livestock farming structure was not obvious. 2) The fluctuation of grassland supply in Kazakhstan has increased, while the consumption due to animal husbandry has also continued to increase, resulting in an increasing pressure on the grassland carrying capacity. 3) Between 2003 and 2017, the overall grassland carrying status of Kazakhstan have been abundant, but the grassland carrying pressure index has shown a steadily increasing trend, the grassland carrying pressure is growing, and it is mainly determined by grassland productivity. The greater pressure in lower Kyzylorda state, the southern Kazakhstan state of the cultivated land and the northern Kazakhstan state has gradually expanded to include the agro-pastoral zone and the semi-desert zone.  相似文献   

Simulation of urban expansion based on cellular automata and maximum entropy model     

Zhang  Yihan  Liu  Xiaoping  Chen  Guangliang  Hu  Guohua 《中国科学:地球科学(英文版)》2020,63(5):701-712

Urban expansion is a hot topic in land use/land cover change(LUCC) researches. In this paper, maximum entropy model and cellular automata(CA) model are coupled into a new CA model(Maxent-CA) for urban expansion. This model can help to obtain transition rules from single-period dataset. Moreover, it can be constructed and calibrated easily with several steps.Firstly, Maxent-CA model was built by using remote sensing data of China in 2000(basic data) and spatial variables(such as population density and Euclidean distance to cities). Secondly, the proposed model was calibrated by analyzing training samples,neighborhood structure and spatial scale. Finally, this model was verified by comparing logistic regression CA model and their simulation results. Experiments showed that suitable sampling ratio(sampling ratio equals the proportion of urban land in the whole region) and von Neumann neighborhood structure will help to yield better results. Spatial structure of simulation results becomes simple as spatial resolution decreases. Besides, simulation accuracy is significantly affected by spatial resolution.Compared to simulation results of logistic regression CA model, Maxent-CA model can avoid clusters phenomenon and obtain better results matching actual situation. It is found that the proposed model performs well in simulating urban expansion of China. It will be helpful for simulating even larger study area in the background of global environment changes.  相似文献   

基于海上风电产业发展的风电机维修市场          下载免费PDF全文

涂亮  刘斯明  郑丹 《海洋开发与管理》2019,36(8):72-76

为促进海上风电产业和风电机维修市场的发展,文章概述风电及其产业的发展状况以及海上风电产业发展的主要地区,分析海上风电机维修市场的需求、特点和潜力,并提出该领域的投资建议。研究结果表明:风电具有巨大的经济、社会和环境效益,是全球发展的重点领域;欧洲、亚洲和美国等是海上风电产业发展的主要地区,其中欧洲发展最早和最好;由于海上风电机结构复杂和所处环境恶劣,维修市场需求旺盛;目前全球海上风电机维修市场具有地区不均衡、核心技术垄断和处于蓝海期的特点,在部件和工具及其供应链供给、运维船制造、智能化产品服务以及人员技能培训等方面具有发展潜力;海上风电机维修市场的自身潜力和辐射效应较大,市场前景广阔,该领域的投资应关注其优势、劣势、机遇和风险。  相似文献   

Characteristics of Temperature Distribution and Control factors in Geothermal Field     

MAO Xiaoping 《《地质学报》英文版》2018,92(Z2):96-98

  相似文献   

乌鲁木齐公共交通基础设施对低收入群体就业的影响研究     

张纯  程志华  于晓萍  王亚群  沈忱 《地理科学进展》2020,39(1):111-119

中国西部城市在大规模、快速度和高投资的交通基础设施推进的同时,审视其建设的社会经济效益就显得尤为重要。尤其对于城市低收入群体来说,公共交通基础设施投入是否能对提升就业水平、提升整体生活品质产生积极作用,值得规划者和决策者关注。论文基于乌鲁木齐2014年居民交通出行调查数据,采用带有交叉变量的多元线性回归和多元Logit回归方法,考察快速公交(Bus Rapid Transit, BRT)对于提升低收入群体就业可达性和通勤满意度的影响。分析结果显示：在就业可达性方面,低收入、男性和拥有住房产权者的通勤时间更长,距离BRT车站越近则通勤时间更短,私家车出行的通勤时间更长;在通勤满意度方面,低收入群体的通勤满意度水平更低,距离BRT车站近、选择私家车出行的通勤满意度水平更高。分析也表明,通勤时间短,通勤满意度水平不一定就高。这些研究结果表明,整体上公共交通基础设施建设对于提升就业可达性和满意度有着积极的带动作用,但个体经济社会属性的差异影响也不可忽视。研究乌鲁木齐公共交通基础设施对就业可达性和满意度的影响,有助于帮助西部城市制定提升低收入群体整体就业水平的公共政策,尤其对于促进地方就业稳定和带动区域经济发展有重要意义。  相似文献   

Carbon pools and fluxes in the China Seas and adjacent oceans     

Nianzhi Jiao  Yantao Liang  Yongyu Zhang  Jihua Liu  Yao Zhang  Rui Zhang  Meixun Zhao  Minhan Dai  Weidong Zhai  Kunshan Gao  Jinming Song  Dongliang Yuan  Chao Li  Guanghui Lin  Xiaoping Huang  Hongqiang Yan  Limin Hu  Zenghu Zhang  Long Wang  Chunjie Cao  Yawei Luo  Tingwei Luo  Nannan Wang  Hongyue Dang  Dongxiao Wang  Si Zhang 《中国科学:地球科学(英文版)》2018,61(11):1535-1563

The China Seas include the South China Sea, East China Sea, Yellow Sea, and Bohai Sea. Located off the Northwestern Pacific margin, covering 4700000 km~2 from tropical to northern temperate zones, and including a variety of continental margins/basins and depths, the China Seas provide typical cases for carbon budget studies. The South China Sea being a deep basin and part of the Western Pacific Warm Pool is characterized by oceanic features; the East China Sea with a wide continental shelf, enormous terrestrial discharges and open margins to the West Pacific, is featured by strong cross-shelf materials transport; the Yellow Sea is featured by the confluence of cold and warm waters; and the Bohai Sea is a shallow semiclosed gulf with strong impacts of human activities. Three large rivers, the Yangtze River, Yellow River, and Pearl River, flow into the East China Sea, the Bohai Sea, and the South China Sea, respectively. The Kuroshio Current at the outer margin of the Chinese continental shelf is one of the two major western boundary currents of the world oceans and its strength and position directly affect the regional climate of China. These characteristics make the China Seas a typical case of marginal seas to study carbon storage and fluxes. This paper systematically analyzes the literature data on the carbon pools and fluxes of the Bohai Sea,Yellow Sea, East China Sea, and South China Sea, including different interfaces(land-sea, sea-air, sediment-water, and marginal sea-open ocean) and different ecosystems(mangroves, wetland, seagrass beds, macroalgae mariculture, coral reefs, euphotic zones, and water column). Among the four seas, the Bohai Sea and South China Sea are acting as CO_2 sources, releasing about0.22 and 13.86–33.60 Tg C yr~(-1) into the atmosphere, respectively, whereas the Yellow Sea and East China Sea are acting as carbon sinks, absorbing about 1.15 and 6.92–23.30 Tg C yr~(-1) of atmospheric CO_2, respectively. Overall, if only the CO_2 exchange at the sea-air interface is considered, the Chinese marginal seas appear to be a source of atmospheric CO_2, with a net release of 6.01–9.33 Tg C yr~(-1), mainly from the inputs of rivers and adjacent oceans. The riverine dissolved inorganic carbon (DIC) input into the Bohai Sea and Yellow Sea, East China Sea, and South China Sea are 5.04, 14.60, and 40.14 Tg C yr~(-1),respectively. The DIC input from adjacent oceans is as high as 144.81 Tg C yr~(-1), significantly exceeding the carbon released from the seas to the atmosphere. In terms of output, the depositional fluxes of organic carbon in the Bohai Sea, Yellow Sea, East China Sea, and South China Sea are 2.00, 3.60, 7.40, and 5.92 Tg C yr~(-1), respectively. The fluxes of organic carbon from the East China Sea and South China Sea to the adjacent oceans are 15.25–36.70 and 43.93 Tg C yr~(-1), respectively. The annual carbon storage of mangroves, wetlands, and seagrass in Chinese coastal waters is 0.36–1.75 Tg C yr~(-1), with a dissolved organic carbon(DOC) output from seagrass beds of up to 0.59 Tg C yr~(-1). Removable organic carbon flux by Chinese macroalgae mariculture account for 0.68 Tg C yr~(-1) and the associated POC depositional and DOC releasing fluxes are 0.14 and 0.82 Tg C yr~(-1), respectively. Thus, in total, the annual output of organic carbon, which is mainly DOC, in the China Seas is 81.72–104.56 Tg C yr~(-1). The DOC efflux from the East China Sea to the adjacent oceans is 15.00–35.00 Tg C yr~(-1). The DOC efflux from the South China Sea is 31.39 Tg C yr~(-1). Although the marginal China Seas seem to be a source of atmospheric CO_2 based on the CO_2 flux at the sea-air interface, the combined effects of the riverine input in the area, oceanic input, depositional export,and microbial carbon pump(DOC conversion and output) indicate that the China Seas represent an important carbon storage area.  相似文献   

Helmert方差分量估计在GPS/GLONASS/BDS组合定位权比确定中的应用     

刘金海  涂锐  张睿  张鹏飞  卢晓春 《大地测量与地球动力学》2018,38(6):568-570

因GNSS系统间观测噪声、轨道精度的差异，采用经验权比进行组合定位难以得到最优结果。基于此，在GPS/GLONASS/BDS组合定位中引入Helmert方差分量估计，对GPS/GLONASS/BDS组合单点定位和基线解算中各系统观测值进行合理定权。实验表明，采用该方法确定的伪距观测值最佳权比为5∶1∶1，相位观测值最佳权比为1∶1∶1，有效提高了GPS/GLONASS/BDS组合定位的精度和可靠性。  相似文献   

水文干旱多变量联合设计及水库影响评估   总被引：2，自引：1，他引：1  

涂新军  杜晓霞  杜奕良  陈晓宏  黎坤 《湖泊科学》2018,30(2):509-518

基于东江流域博罗站月径流数据,采用游程理论提取水文干旱事件.选用Meta-Gaussian Copula函数,统计模拟水文干旱指标的多变量联合分布.采用Kendall联合重现期和最大可能权函数,设计给定联合超越重现期的水文干旱指标组合值,并定量评估水库径流调节作用对水文干旱多变量联合特征的影响.结果表明:东江流域水文干旱历时、强度和峰值的统计优选分布均为韦布尔分布.干旱指标之间具有较高的正相关性,Meta-Gaussian Copula能够很好地模拟水文干旱指标两变量和三变量联合分布.基于任意两个变量联合设计和三变量联合设计,干旱指标设计组合值位于同频位置附近,且同一个干旱指标设计值在不同变量组合之间差别较小.水库径流调节作用对于缓解东江流域水文干旱效果明显,同一组干旱指标的多变量联合超越重现期在水库影响下明显变大.联合超越重现期越小,水库对联合设计值的影响程度越大.根据目前水库运行模式,若要满足河道内最小管理流量目标,联合超越重现期10 a一遇的干旱历时、强度和峰值依然达到了约3.89~4.04月、7.20~7.97亿m3和2.99~3.12亿m3.  相似文献   

土耳其卡赞天然碱溶采对接井堵井原因分析及修复          下载免费PDF全文

涂运中  张正元  刘海翔  刘汪威  胡汉月 《探矿工程》2020,47(8):64-71

土耳其卡赞天然碱矿由于地质条件复杂，首采层不溶物含量高，矿层倾角大，在商业开采过程中易发生堵井事故。本文以P078水平对接井组为例，介绍了其施工工艺和注采井史，分析了引起井组堵塞的原因。遵循“先易后难、降低风险、控制成本”的原则，先后进行了直井单井循环、固井泵车压井和循环泥浆清理井底等各种尝试，最后提出了分支侧钻重新连通的技术方案，并成功修复了溶采通道，恢复了井组的正常生产。并在钻井施工组织、修井设计与施工和溶采作业等方面提出了建议。该技术对类似故障井组的修复具有一定的指导作用和借鉴意义。  相似文献   

微型近红外光谱仪测量北极积雪覆盖海冰内部太阳辐照度可行性研究   总被引：1，自引：1，他引：0  

南立文  王晓萍  王杭州  周宏亮  陈鹰 《海洋学报(英文版)》2020,39(9):115-124

The extremely low temperature, high humidity and limited power supply pose considerable challenges when using spectrometers within the Arctic sea ice. The feasibility of using a miniature low-power near-infrared spectrometer module to measure solar radiation in Arctic sea ice environments was investigated in this study.Temperature and integration time dependences of the spectrometer module were examined over the entire target operating range of –50℃ to 30℃, well below the specified operating range of this spectrometer. Using these observations, a dark output prediction model was developed to represent dark output as a function of temperature and integration time. Temperature-induced biases in the saturation output and linear operating range of the spectrometer were also determined. Temperature and integration time dependences of the signal output were evaluated. Two signal output correction models were developed and compared, to convert the signal output at any temperature within the operating temperature range and integration time to that measured at the reference temperature and integration time. The overall performance of the spectrometer was evaluated by integrating it into a refined fiber optic spectrometry system and measuring solar irradiance distribution in the ice cover with thickness of 1.85 m in the Arctic during the 9th Chinese National Arctic Research Expedition. The general shape of the measured solar irradiance above the snow surface agreed well with that measured by other commercial oceanographic spectroradiometers. The measured optical properties of the sea ice were generally comparable to those of similar ice measured using other instruments. This approach provides a general framework for assessing the feasibility of using spectrometers for applications in cold environments.  相似文献