A2和B2排放情景下气候变化对福建省水稻生产的阶段性影响     

江敏  石春林  薛昌颖 《气象与环境科学》2015,38(4):38-46

选择IPCC排放情景特别报告(SRES)中的A2和B2方案,利用区域气候模式PRECIS构建的气候变化情景文件与作物模型(CERES-Rice)耦合,采用雨养与灌溉两种方式,并综合考虑未来CO2浓度增加带来的直接增益效应,模拟了未来2020s及2040s两个时段气候变化对福建省水稻生育期与产量的影响。结果表明:无论是雨养方式还是灌溉方式,未来全省各稻区水稻生育期都将缩短,并且随着温度增高,2040s时段缩短的时间较2020s更长,单季稻生育期缩短时间最长,可达15~20 d。雨养条件下,除了闽东南双季稻区后季稻在2020s时段表现为2.3%(A2)和3.1%(B2)较小幅度的增产外,其他稻区各种稻作制度下的水稻产量较之BASE均出现了不同幅度的减产。闽西北稻区后季稻减产幅度最大,2020s时段A2和B2情景下减产幅度依次为6.9%和10.2%,2040s时段减产幅度进一步加大至14.1%和15.6%。闽东南稻区后季稻模拟结果较为乐观,尤其是在灌溉条件下表现为不同幅度的增产,两种情景下分别增产了1.7%、3.9%。双季稻种植区的后季稻产量稳定性均不如早稻和单季稻的,且随着温度升高,到2040s产量不稳定性有增加的趋势。灌溉在一定程度上可以缓解未来高温天气带来的产量波动。从全省的总产变化趋势来看,A2和B2两种排放情景模拟的结果都不容乐观,即使采用充分灌溉的方式,也依旧表现为减产。2020s时段,两种情景下分别减产0.74%与2.44%;2040s时段,两种情景下减产为3.50%与3.23%。未来早稻和单季稻生长季的土壤水分条件将变得不如目前湿润,与之相关的灌溉需要量均有所增加。  相似文献   

改性红辉沸石的制备及去除水中CODcr的性能研究     

张静  肖筱瑜  徐文炘 《矿产与地质》2010,24(6):570-573

天然红辉沸石经过氯化铝及氯化镁共同改性后,制备出改性红辉沸石。研究了改性红辉沸石和天然红辉沸石对生活污水中CODcr的吸附效果,表明改性红辉沸石的吸附效果明显优于红辉沸石,并通过X射线粉末衍射、热重分析、红外光谱对改性红辉沸石表面结构进行了表征。  相似文献   

中国科技资源配置效率测度及其时空格局演变特征(英文)     

范斐  杜德斌  王馨竹 《地理学报(英文版)》2014,24(3):492-508

According to the connotation and structure of science and technology resources and some relevant data of more than 286 cities at prefecture level and above during 2001–2010, using modified method—Data Envelopment Analysis(DEA), science and technology(ST) resource allocation efficiency of different cities in different periods has been figured out, which, uncovers the distributional difference and change law of ST resource allocation efficiency from the time-space dimension. Based on that, this paper has analyzed and discussed the spatial distribution pattern and evolution trend of ST resource allocation efficiency in different cities by virtue of the Exploratory Spatial Data Analysis(ESDA). It turned out that:(1) the average of ST resource allocation efficiency in cities at prefecture level and above has always stayed at low levels, moreover, with repeated fluctuations between high and low, which shows a decreasing trend year by year. Besides, the gap between the East and the West is widening.(2) The asymmetrical distribution of ST resource allocation efficiency presents a spatial pattern of successively decreasing from Eastern China, Central China to Western China. The cities whose ST resource allocation efficiency are at higher level and high level take on a cluster distribution, which fits well with the 23 forming urban agglomerations in China.(3) The coupling degree between ST resource allocation efficiency and economic environment assumes a certain positive correlation, but not completely the same. The differentiation of ST resource allocation efficiency is common in regional development, whose existence and evolution are directly or indirectly influenced by and regarded as the reflection of many elements, such as geographical location, the natural endowment and environment of ST resources and so on.(4) In the perspective of the evolution of spatial structure, ST resource allocation efficiency of the cities at prefecture level and above shows a notable spatial autocorrelation, which in every period presents a positive correlation. The spatial distribution of ST resource allocation efficiency in neighboring cities seems to be similar in group, which tends to escalate stepwise. Meanwhile, the whole differentiation of geographical space has a diminishing tendency.(5) Viewed from LISA agglomeration map ofST resource allocation efficiency in different periods, four agglomeration types have changed differently in spatial location and the range of spatial agglomeration. And the continuity of ST resource allocation efficiency in geographical space is gradually increasing.  相似文献   

基于GIS的合肥市BRT和Metro交通可达性研究   总被引：1，自引：0，他引：1  

朱传华  张守文 《地理与地理信息科学》2014,30(6)

评价了合肥市中心城区的BRT和在建Metro线路对可达性的影响。基于GIS网络分析模拟复杂的多模式交通网络,应用修正潜能模型指标度量了居民区与CBD、与商业金融中心、与行政中心以及与工业区的可达性,对比有无BRT和Metro两种情景下的可达性变化。研究结果表明:在有BRT和Metro时,居民区至CBD的可达性均值变化幅度为45.8%,出行时间从65.5min减至35.5min;居民区至商业金融中心的可达性均值变化幅度为45.7%,时间从74.8min减至40.6min;居民区至行政中心的可达性均值变化幅度为18.9%,时间从104.7min减至84.9min;居民区至工业区的可达性均值变化幅度为37.4%,时间从92.1min减至57.7min。BRT和Metro线路显著地节省了居民出行时间,改善了城市边缘区域的交通可达性,其中经开区的可达性变化幅度最高,其次是滨湖新区、高新区和东区、老城区、南区、西区和北区。  相似文献   

特征约束六面体网格生成的改进栅格法     

庞宇  郭飞  李想  何梅芳 《地球信息科学学报》2014,(5):691-698

目前,针对地学对象的非结构化六面体网格生成问题仍未得到很好的解决。为满足相关地学研究对六面体网格的需求,促进地学模拟及传统GIS空间分析的进一步发展,本文对传统栅格法进行扩展,提出了一种面向地学研究的六面体网格生成的改进栅格法。通过提取实体模型表面的几何特征,考虑内部孔、洞约束生成骨干网格,在此基础上构建一套特征约束模板来处理复杂的特征约束,使之既能保持地学研究对象的几何形态特征,又能实现加密区域与非加密区域的平滑过渡,从而满足地学分析与模拟的需求。  相似文献   

Amodified discrete element model for sea ice dynamics     

LI Baohui  LI Hai  LIU Yu  WANG Anliang  JI Shunying 《海洋学报(英文版)》2014,33(1):56-63

Considering the discontinuous characteristics of sea ice on various scales,a modified discrete element model（DEM） for sea ice dynamics is developed based on the granular material rheology.In this modified DEM,a soft sea ice particle element is introduced as a self-adjustive particle size function.Each ice particle can be treated as an assembly of ice floes,with its concentration and thickness changing to variable sizes under the conservation of mass.In this model,the contact forces among ice particles are calculated using a viscous-elastic-plastic model,while the maximum shear forces are described with the Mohr-Coulomb friction law.With this modified DEM,the ice flow dynamics is simulated under the drags of wind and current in a channel of various widths.The thicknesses,concentrations and velocities of ice particles are obtained,and then reasonable dynamic process is analyzed.The sea ice dynamic process is also simulated in a vortex wind field.Taking the influence of thermodynamics into account,this modified DEM will be improved in the future work.  相似文献   

A modified global model for predicting the tritium distribution in precipitation, 1960–2005     

Yanhong Zhang  Shujun Ye  Jichun Wu 《水文研究》2011,25(15):2379-2392

A modified global model for predicting the tritium concentration in precipitation has been developed using the dataset of International Atomic Energy Agency/the World Meteorological Organization (IAEA/WMO) over the period from 1960 to 2005. The tritium concentration in precipitation and its history can be estimated at any location using the model. The modified global model of tritium in precipitation (MGMTP) here presented has higher accuracy than the global model of tritium in precipitation (GMTP) developed by Doney et al. ( 1992 ). The new model is not only more appropriate for a particular station but also applicable for the un‐normalized observations directly. Another advantage of MGMTP is that it can estimate a longer history (from 1960 to 2005) of tritium content in precipitation than GMTP (from 1960 to 1986). The seasonal cycle of tritium in precipitation has also been modelled in the form of a simple cosine function with five parameters. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

融合时间序列环境卫星数据与物候特征的水稻种植区提取   总被引：3，自引：0，他引：3  

柳文杰  曾永年  张猛 《遥感学报》2018,22(3):381-391

获取高精度的区域水稻种植面积对于农业规划、配置与决策具有重要意义。区域尺度的水稻面积获取依赖于高时空分辨率影像,但受卫星回访周期和气候影响,难以获取足够时间序列的高时空分辨率影像,从而影响水稻种植面积遥感提取的精度。为此,提出适应于中国南方多雨云天气地区,基于国产环境卫星(HJ-1A/1B)与MODIS融合数据的水稻种植面积提取的新方法。以洞庭湖区为实验区,利用STARFM模型融合环境卫星NDVI数据与MODIS13Q1数据,获取时间序列的环境卫星NDVI数据,利用水稻关键期的NDVI数据结合物候特征参数对水稻种植区域进行提取。结果表明,该方法能有效提取区域水稻种植的面积,水稻种植面积提取的总体精度与Kappa系数分别达到91.71%与0.9024,分类结果明显优于仅采用多光谱影像或NDVI数据。该研究为中国南方多雨云天气地区水稻种植面积提取提供了有效的方法。  相似文献   

考虑桩体刺入变形的透水混凝土桩复合地基固结理论研究     

韩柏林卢萌盟 《岩土力学》2023,(8):2360-2368

现有的多元复合地基利用两种或者两种以上的桩型对地基土进行加固,以期提高地基承载力、加速地基固结。提出了一种兼具散体材料桩和刚性不排水桩自身优点的透水混凝土桩复合地基固结模型。工程中刚性桩与土体的压缩量并不相等,这与等应变条件存在着不一致的地方。为此,抛弃传统等应变假设,考虑桩体向垫层和下卧层的刺入变形,对传统等应变假定进行修正,同时考虑了扰动区土体水平渗透系数的抛物线变化和水在桩体内的径向、竖向渗流,给出了此类固结问题的控制方程和解答以及复合地基固结度的表达式,并对复合地基固结度的解进行了讨论。最后与其他复合地基解做了比较并对固结性状进行了分析,并针对透水混凝土桩孔隙引起的桩阻作用对地基固结速度的影响进行了验证。  相似文献   

分层土中裙式吸力基础吸力沉贯特性模型试验研究     

张雨坤  秦廷辉  李大勇  王冲冲 《岩土力学》2022,43(5):1317-1325

针对一种新型海上风电基础形式-裙式吸力基础,开展模型试验,研究其在分层土地基中的沉贯特性。讨论了土层分布形式（砂土、黏性土、上层砂土及下层黏性土（简称上砂下黏）、上层黏性土及下层砂土（简称上黏下砂））、沉贯方式的影响。研究表明：裙式吸力基础在分层土中具有良好的沉贯性能。与传统吸力基础相比,裙式吸力基础在砂土、黏性土、上砂下黏和上黏下砂地基中最终沉贯深度较传统吸力基础分别增加10.0%、2.3%、3.0%和9.6%,沉贯最大吸力值分别增加0.9%、14.4%、66.2%和92.2%。黏性土层位置和厚度对基础沉贯特性影响显著。上黏下砂地层中,基础最大吸力值出现在土层分界面处,最大吸力值随土层分布系数t（上层土厚度与土体总厚度的比值）的增加而逐渐增大,最终沉贯深度随土层分布系数增加而逐渐减小。上砂下黏地层中,裙式吸力基础最大吸力值出现在最大沉贯深度处,吸力最大值随土层分布系数的增加而逐渐减小,最终沉贯深度受土层分布系数影响较小。此外,同时抽吸主桶和裙结构内水体进行沉贯,最终沉贯深度大于只抽主桶情况。在砂土、黏性土、上黏下砂（ 0.4）和上砂下黏（ 0.4）等4种地基中,裙式吸力基础采用同时抽主桶和裙结构的沉贯方式,最终沉贯深度较只抽主桶情况分别增大了13.8%、3.4%、16.4%和4.6%。研究成果为进一步阐明吸力基础在分层土中沉贯机制及指导工程实践,具有借鉴意义。  相似文献