1998-2012年中国耕地复种指数时空差异及动因   总被引：7，自引：0，他引：7  

谢花林  刘桂英 《地理学报》2015,(4)

从国家、区域和省级三个层面上分析了1998-2012年间中国耕地复种指数的变化趋势,并基于Theil指数探讨了中国耕地复种指数的时空差异,利用计量经济学模型从人文视角探讨了耕地复种指数变化的影响因素。结果表明:1在全国尺度上,中国耕地复种指数总体上呈逐年增长的趋势。2在区域尺度上,复种指数最高的为中部地区,最低的为东北地区;而复种指数增长最快的是东北地区,最慢的是中部地区,东部地区呈下降趋势。3中国31个省份复种指数各不相同,且差距大,复种指数增长最快的是新疆、宁夏和云南。4由Theil指数值的大小可知,中国耕地复种指数的差异呈缩小态势,其主要原因为四大区域间的差异。5人口非农化比重对耕地复种指数产生了显著负向作用,产业非农化比重、农业政策、人均经营耕地和农村家庭人均经营纯收入对耕地复种指数产生了显著正向作用。最后,本文认为转移农村剩余劳动力,提高农民的经营性收入水平,促进土地流转,形成土地规模化经营,以及进一步加大对欠发达地区及粮食主产区农业发展的惠农扶持力度,充分发挥国家惠农政策的诱致作用,有利于全面提高中国耕地复种水平。  相似文献   

Depositional system and palaeoclimatic interpretations of Middle to Late Pleistocene travertines: Kocabaş, Denizli,south‐west Turkey          下载免费PDF全文

Ezher Toker  Mine Sezgül Kayseri‐Özer  Mehmet Özkul  Sándor Kele 《Sedimentology》2015,62(5):1360-1383

Travertine deposits in western Turkey are very well‐exposed in the area of Kocaba?, in the eastern part of the Denizli Basin. The palaeoclimatic significance of these travertines is discussed using U/Th dates, stable isotope data and palynological evidence. The Kocaba? travertine occurrences are characterized by successions of depositional terraces associated with palaeosols and karstic features. The travertines have been classified into eight lithotypes and one erosional horizon, namely: laminated, coated bubble, reed, paper‐thin raft, intraclasts, micritic travertine with gastropods, extra‐formational pebbles and a palaeosol layer. The analysed travertines mostly formed between 181 ka and 80 ka (Middle to Late Pleistocene) during a series of climatic changes including glacial and interglacial intervals; their δ¹³C and δ¹⁸O values indicate that the depositional waters were mainly of basinal thermal origin, occasionally mixed with surficial meteoric water. Palynological results obtained from the palaeosols showed an abundance of non‐arboreal percentage and xerophytic plants (Oleaceae and Quercus evergreen type) indicating that a drought occurred. Marine Isotope Stage 6 is represented by grassland species but Marine Isotope Stage 5 is represented by Pinaceae–Pinus and Abies, Quercus and Oleaceae. Uranium/thorium analyses of the Kocaba? travertines show that deposition began in Marine Isotope Stage 6 (glacial) and continued to Marine Isotope Stage 4 (glacial), but mostly occurred in Marine Isotope Stage 5 (interglacial). The travertine deposition continued to ca 80 ka in the south‐west of the study area, in one particular depression depositional system. Palaeoenvironmental indicators suggest that the travertine depositional evolution was probably controlled by fault‐related movements that influenced groundwater flow. Good correlation of the stable isotope values and dates of deposition of the travertines and palynological data of palaeosols in the Kocaba? travertines serve as a starting point for further palaeoclimate studies in south‐west Turkey. Additionally, the study can be compared with other regional palaeoclimate archives.  相似文献   

新疆阿尔泰巴特巴克布拉克铁矿床成矿作用研究   总被引：2，自引：0，他引：2       下载免费PDF全文

杨俊杰  柴凤梅  杨富全  张志欣 《地质科学》2015,(3):879-897

巴特巴克布拉克铁矿床赋存于上志留-下泥盆统康布铁堡组变质火山-沉积岩系中, 近矿围岩为石榴子石矽卡岩、角闪斜长变粒岩和浅粒岩。矿体总体顺层分布, 呈似层状、透镜状及不规则状, 空间上与矽卡岩密切相关。流体包裹体研究表明, 矽卡岩阶段形成的石榴子石中发育纯气体包裹体、气体包裹体、液体包裹体、含子矿物包裹体及熔融包裹体; 退化蚀变阶段发育液体包裹体和少量气体包裹体; 石英-硫化物阶段主要发育液体包裹体、含液体CO₂的三相包裹体及少量纯气体包裹体、气体包裹体和含子矿物包裹体。矽卡岩阶段均一温度变化为217 ℃~499 ℃, 在255 ℃出现峰值, 盐度(NaCl_eq)变化为8.68%~22.65%; 退化蚀变阶段均一温度变化为181 ℃~432 ℃, 在225 ℃出现峰值, 盐度变化为12.85%~22.65%; 石英-硫化物阶段均一温度变化为140 ℃~482 ℃, 在155 ℃出现峰值, 盐度变化为0.18%~42.40%。石榴子石、石英和方解石的 δ¹⁸ O_SMOW 变化为1.8‰~7.1‰, δ¹⁸Ο_Η2Ο为 -4.79‰~4.57‰, δD_SMOW 为 -128‰~-84‰, 表明矽卡岩阶段成矿流体主要为岩浆水, 混合少量大气降水; 石英-硫化物阶段大气降水所占比例明显增加。方解石δ¹³ C_V-PDB 变化为 -3.2‰~-2.0‰, 表明流体中的碳来自深部或地幔。  相似文献   

方程误差系统的多新息辨识方法     

丁锋 《南京气象学院学报》2015,7(5):385-407

多新息方法可以用于线性系统和非线性系统的自适应滤波、参数估计、自校正控制、自适应故障检测与诊断等.线性系统包括两种基本类型:方程误差类系统和输出误差类系统.本文将多新息辨识应用到方程误差滑动平均(EEMA)系统(即CARMA系统),研究多新息增广随机梯度算法和多新息增广最小二乘算法,应用到方程误差自回归滑动平均(EEARMA)系统(即CARARMA系统),提出基于分解的多新息广义增广随机梯度算法和基于分解的多新息广义增广最小二乘算法,以及基于滤波的多新息广义增广随机梯度算法和基于滤波的多新息广义增广最小二乘算法.  相似文献   

Sustainability evaluation of different systems for sea cucumber (Apostichopus japonicus) farming based on emergy theory     

Wang  Guodong  Dong  Shuanglin  Tian  Xiangli  Gao  Qinfeng  Wang  Fang 《中国海洋大学学报(英文版)》2015,14(3):503-510

Emergy analysis is effective for analyzing ecological economic systems. However, the accuracy of the approach is af-fected by the diversity of economic level, meteorological and hydrological parameters...  相似文献   

利用MPI实现多幅点云ICP并行配准     

崔家武  周波阳  张兴福  柴向浩  樊树春 《测绘通报》2021,(3):87-90

迭代最近点算法（ICP）是一种用于点云精确配准的经典算法。针对多幅点云进行ICP配准存在耗时多、效率低的问题,本文利用消息传递接口MPI对多幅点云进行分批并行配准。首先并行求解相邻两幅点云的相邻变换矩阵,然后计算每幅点云在当前批次的局部变换矩阵,最后获得每幅点云的全局变换矩阵。本文以DELL PowerEdge R730服务器为计算平台,对空间点总规模达四千多万的65幅点云进行了分批并行配准。试验结果表明：利用MPI对多幅点云进行分批处理可显著加快配准速度,最优进程数为计算机的核数时,加速比为5.3。  相似文献   

吉尔吉斯斯坦布丘克造山型金矿床：来自流体包裹体、H- O- S同位素证据     

史鹏亮  屈海浪  鄂建新  刘春发  缪广  马麒镒  戴毅 《地质学报》2023,97(3):738-752

吉尔吉斯斯坦北天山构造带的矿床学数据缺乏,制约了天山造山带境内外成矿对比。布丘克金矿床位于吉尔吉斯斯坦北天山构造带中部。金矿体为石英复脉,呈带状发育于NWW向韧性剪切带中。矿体倾向SSW,倾角60°～70°,赋矿围岩主要为侵入于早古生代变质碎屑杂岩中的正长斑岩。布丘克金矿床成矿期石英流体包裹体观察、石英H-O同位素、硫化物S同位素测试结果显示,布丘克金矿床石英脉中包裹体大小集中在2～10μm之间,类型以H₂O-CO₂型、富CO₂型、水溶液型包裹体为主,成分以富CO₂、含CH₄为特征。成矿流体具有中温(200～320℃)、低盐度(3%～7%NaCl_eqv)特征;石英δD_V-SMOW值介于-108.1‰～-90.2‰之间,δ¹⁸O_流体值介于4.86‰～9.26‰之间;黄铁矿δ³⁴S分布在0‰左右(-0.9‰～1.6‰)。综合本文数据、矿床地质特征、区域地质资料,本文认为布丘...  相似文献   

经济空间场与ESDA结合的公共卫生事件应急策略制定     

俞艳  蒙文清  樊建  马薇霖  夏杨玲 《武汉大学学报(信息科学版)》2021,(2)

新型冠状病毒肺炎疫情引起了人们对国家公共卫生事件应对能力的广泛关注。基于波及效应梯度场提出了生产诱发梯度,进一步完善了经济空间场理论,并将其与探索性空间数据分析(exploratory spatial data analysis,ESDA)相结合,对医药制造业波及效应及空间布局进行了研究,制定了有效的公共卫生事件应急策略。经济空间场理论分析结果揭示了产业经济空间中医药制造业与各产业部门之间的波及效应,并由此得到了医药密切相关产业。同时,经济空间场理论与ESDA方法的结合能在区分中国大陆各省空间聚集类型的基础上,评估各省公共卫生事件的应对能力,从而为各省提出相应的应急策略和医药制造业发展建议。该方法综合考虑了产业波及效应和产业空间布局现状,不仅能够促进各省医药制造业的健康合理发展,也有助于增强各省突发公共卫生事件的应对能力。  相似文献   

多重散射问题的改进算法以及双排非连续弹性屏障对水平向剪切波的隔离研究     

夏唐代  孙苗苗  陈晨 《岩土力学》2011,32(8):2402-2408

与Aviles等学者的多重散射隔振理论相比较,采用更为完整的Fourier-Bessel函数系的级数展开表达式来研究弹性波入射下的多重散射问题。引入Graf加法定理,并结合位移和应力边界条件,推导了无限均匀弹性介质中任意分布的多个弹性圆柱体对于平面水平向剪切波(SH波)入射时散射系数的理论解析解。随后,取圆柱体分布于两条相互平行的直线上,则问题演变为双排弹性桩屏障对于弹性波的隔离问题。引入无量纲位移(屏障后土体总的位移与仅由入射平面水平向剪切波引起的位移的比值)和透射系数(屏障宽度范围内无量纲位移的几何平均值)的概念来研究屏障的隔振效果。重点讨论了双排桩间距h以及桩土的剪切模量比ξ对于屏障整体隔振效果的影响,阐述了双排桩屏障的隔振性状。特别地,当h=0时,该问题退化为常见的单排非连续屏障的隔振问题。  相似文献   

Variability of Nonionellina labradorica Dawson in Surface Sediments from Kongsfjorden, West Spitsbergen     

Suhas SHETYE  Rahul MOHAN  Sunil Kumar SHUKLA  Sudhakar MARUTHADU  Rasik RAVINDRA 《《地质学报》英文版》2011,85(3):549-558

Kongsfjorden is a fjord in Spitsbergen (Svalbard archipelago) that lies adjacent to both Arctic and Atlantic water masses and is therefore a suitable site to understand the effects of climate change on ecosystems. To decipher the effect of the lateral advection of transformed Atlantic water (TAW) within the fjord, spatial variations of foraminiferal tests, their test size variations and stable isotopic composition (δ13C and δ18O) in the surface sediments were studied. Total organic carbon and textural analyses were also carried out. The dominant benthic foraminifera included Nonionellina labradorica, Elphidium excavatum, Cassidulina reniforme, Quinqueloculina stalkeri and Islandiella islandica. Nonionellina labradorica was the predominant species in the outer fjord, whereas Elphidium excavatum and Cassidulina reniforme were dominant in the inner fjord. Total organic carbon and the test size of Nonionellina labradorica within the fjord were highly correlated (r2?=?0.97) and both showed a decreasing trend towards the inner fjord. Based on the distribution and abundance of Nonionellina labradorica as well as temperature profiles, we suggest that there was little or no major change in the lateral advection of TAW within the fjord in the immediate past.  相似文献