西南丘陵山区县域耕地占补平衡预警研究——以重庆市永川区为例

以重庆市永川区为例,在深入分析永川区社会经济发展以及自然环境现状特征的基础上,构建了包括生产性、可行性、可接受性以及保持性4个目标因子的丘陵山区县域耕地占补平衡预警指标体系框架;运用实证研究法、耦合分析法等研究方法对2005-2020年永川区耕地占补平衡预警进行了判定,结合永川区耕地资源利用的实际情况以及耕地占补平衡预警结果,就如何提高区域耕地占补平衡水平提出了建议;研究成果可为科学调控丘陵山区县域耕地占补平衡和保障区域粮食安全生产提供科学依据.     

基于改进SPA的乐山市耕地生态安全评价

耕地生态安全评价是对农田生态复合系统的全面诊断,也是测度区域可持续发展的重要内容.本文以四川省乐山市为例,在界定耕地生态安全内涵的基础上,构建基于PSR模型的评价指标体系,并采用改进的SPA法分别对乐山市及各区县2007,2009,2012年耕地生态安全进行评价,并对其变化因素进行了分析.结果表明:1)乐山市耕地生态安全水平整体上呈上升趋势,安全等级由"临界安全"逐渐演变为"较安全",区域上呈现出北高南低的现象;2)耕地资源数量和质量、生态环境的优劣、经济发展水平是导致南北耕地生态安全差异的主要因素;3)改进的SPA法能够揭示耕地生态安全评价指标体系的分异程度,提取综合评价结果的中间信息,在耕地生态安全评价中具有一定实用价值.     

基于PSR框架的甘肃省环县耕地生态安全评价

以生态退化区甘肃环县为研究区,通过构建"压力-状态-响应"(PSR)模型,从自然、经济和社会3个方面选取20个评价指标,建立耕地生态安全评价指标体系,计算耕地生态安全指数并划分安全等级,对2005-2016年环县耕地生态安全变化状况进行定量分析.结果表明:①基于PSR模型的评价指标体系能够较好地反映耕地生态系统各个要素之间的关联,适用于区域耕地生态安全的综合评价.②2005-2016年期间,环县耕地生态安全水平逐渐提高,生态功能有所改善,耕地生态安全经历了"恶化-敏感-安全"的演变过程.③单项指标的变化表明环县2005-2016年间人口密度、人均耕地面积、土地垦殖率、单位面积耕地化肥施用量、年降水量以及工业废水排放达标率变化明显,是影响区域耕地生态安全状况的关键因素.今后在加强对耕地数量保护的同时,应采取休耕等耕地休养方式加强耕地质量和耕地生态建设与维护,致力于耕地生态系统的恢复和重建,促进区域耕地可持续利用.     

基于熵权法的南县土地生态安全评价

基于PSR模型,从压力、状态和响应3方面构建南县土地生态安全评价指标体系,利用熵权法分析2009-2013年南县土地生态安全状况.评价结果表明,总体而言,2009-2013年南县土地生态安全水平呈逐年恶化趋势,由临界安全等级降为不安全等级;就子系统而言,压力子系统土地生态安全水平虽呈波动式上升趋势,但仍处于非常不安全等级,状态和响应子系统都呈波动式下降趋势,由不安全等级降为非常不安全等级;影响土地生态安全的主要子系统为响应子系统,其中城市化率、单位播种耕地粮食产量、单位耕地化肥使用量、水土协调度、第三产业比重、环保投资占GDP比重、工业废水达标排放率等为主要因素指标.     

湖北省耕地生态安全时空演变特征研究

耕地生态安全评价是改善耕地生态系统状况、促进耕地可持续利用的重要基础。以湖北省为研究区域,借助DPSIR模型构建耕地生态安全评价指标和熵权法确定指标权重,运用GIS对湖北省耕地生态安全水平和空间分布特征进行定量研究。研究结果表明:1)2002-2011年湖北省耕地生态安全水平总体不断提高,安全等级经历了2002-2006年"风险-敏感"阶段和2007-2011年"临界安全-比较安全"阶段的演变历程;2)2002-2011年的Moran′s I值表明湖北省耕地生态安全水平具有较明显的空间聚集特征,其中2008年Moran′s I值最高;17个单元的局部自相关指数表明湖北省各行政单元的耕地生态安全水平在空间上也具有一定的集聚或分异特征。研究结果可为湖北省耕地生态安全态势的预测与预警、促进耕地可持续利用提供决策参考。     

耕地后备资源匮乏区建设用地可扩展空间测度研究——以山东省为例

在耕地占补平衡政策下,科学测算耕地后备资源匮乏地区的建设用地可扩展空间,对于充分认识区域发展的资源约束性有着重要意义.本文以山东省为例,构建了耕地后备资源-耕地占补平衡-可扩展空间模型,测算了全省及各区域建设用地可扩展空间和可使用年限,划分了可扩展空间类型区,提出了差别化的土地利用优化措施.结果表明:1)山东省补充耕地能力和建设用地可扩展空间总量有限且分布不均,全省补充耕地总能力为18.67万hm~2,建设用地可扩展空间总量为27.19万hm~2.经济社会发达地区,补充耕地能力和可扩展空间分布较少;经济社会欠发达地区分布相对较多.2)全省各县(市、区)可使用年限差异较大,高度约束区仅可满足近期5年用地需求,中等约束区可满足中期5～15年用地需求,低度约束区可满足远期15年以上用地需求.研究结论:测算结果能够反映山东省土地资源利用的实际情况,可以为省域内占补平衡指标调剂、空间规划的编制及生态保护提供参考.     

耕地生态安全评价及时空格局分析——以传统农业区河南省周口市为例

针对传统农业区内耕地生态安全状况,以河南省周口市为研究区域,基于人与耕地相互作用机理,运用改进的PSR模型构建适用于研究区域的评价指标体系,采用组合赋权法和多因素综合评价法,对2001-2013年间全市及下属10个县区的耕地生态安全水平进行时空格局分析,结果表明:(1)从时间尺度上看,周口市耕地生态安全综合值呈现出"下降—上升—下降—上升"的波动变化且安全值相对较低,相应的安全等级也经历了"较不安全—临界安全—较安全—临界安全"的倒"U"型发展阶段.(2)从空间尺度上看,各县区耕地生态安全状况存在着明显的地带性差异.安全和较安全区主要集中在周口市的中部和西南部地区,并随着安全状况的变化向东部、北部扩展或缩减;临界安全区的分布变动幅度较大,但主要集中在周口市北部、东部和南部6个县区;较不安全和不安全等级仅在2001年和2003年有所分布.2001年较不安全区主要集中在南部的项城和沈丘,但随着环境的继续恶化,到了2003年,该分布范围蔓延到了东北部的郸城和鹿邑,并且项城沦为了研究期内唯一的不安全分布区.     

基于改进蒙特卡洛模拟的耕地生态安全时空特征研究 ——以齐齐哈尔市为例

为解决耕地生态安全评价中高维指标权重赋值难,及由此导致的评价结果不确定性的问题,以齐齐哈尔市为例,通过引入蒙特卡洛模拟,采用三角分布模型对蒙特卡洛模拟中权重值域不合理问题进行了改进,构建了基于PSR(压力-状态-响应)模型的耕地生态安全评价指标体系,利用Python语言编程实现了模拟计算过程,从时空角度分析了区域耕地生态安全状况.结果表明:(1)近15年齐齐哈尔市耕地生态安全值从0.333增长至0.641,呈现"缓和下降—快速增长—平稳上升"的阶段性发展特点,耕地生态安全状态呈逐渐改善趋势;(2)依据各区县耕地生态安全值时空变化特征可以将齐齐哈尔市划分为耕地生态安全良好区、缓和区与风险区三类,其分布具有一定的空间聚集特征;(3)改进的蒙特卡洛模拟优化了权重值域分布,可以量化因权重差异导致的最终评价结果的不确定性,使得评价结果更客观、可靠.运用改进的蒙特卡洛模拟可以客观真实地反映齐齐哈尔市耕地生态安全状况,对齐齐哈尔市耕地资源利用、因地制宜地兼顾生态文明建设与经济发展需求具有重要意义.     

区域生态安全的模糊多层次评价

在分析区域生态环境系统层次结构的基础上,提出了区域生态安全的三级评价指标体系,即准则层、一级指标层、二级指标层,准则层基于P-S-R模型分为生态环境系统状态、人文社会压力、环境污染压力、人文社会响应四部分;介绍了模糊多层次评价模型的构建,利用模糊多层次评价方法对铜川市的生态安全进行评价,评价结果为"临界安全".     

利用GIS技术进行耕地占补平衡工作的探讨

介绍了GIS技术,针对我国目前耕地占补平衡工作的技术上的不足.提出了利用GIS进行耕地占补平衡工作的技术方案,结合山西省的实际情况,对耕地等级数据库的建立、耕地占补平衡系统的开发进行了较为详细的阐述.     

Characterization of Ordovician carbonate reservoirs, southeastern Saskatchewan, Canada

The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3～4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰～ -7.8‰, PDB) and matrix dolomites (-6.6‰～ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084～0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078～0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.     

A computer generator for randomly layered structures

AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…     

海南岛地体及其毗邻陆缘晚中生代—新生代古地磁研究和构造演化

本文叙述了对海南岛及其毗邻大陆边缘白垩纪到第四纪地层岩石进行古地磁研究的全部工作过程。通过分析岩石中剩余磁矢量的磁偏角及磁倾角的变化,提出海南岛白垩纪以来经历的构造演化模式如下:早期伴随顺时针旋转而向南迁移,后期伴随逆时针转动并向北运移。联系该地区及邻区的地质、地球物理资料,对海南岛上述的构造地体运动提出以下认识:北部湾内早期有一拉张作用,主要是该作用使湾内地壳显著伸长减薄,形成北部湾盆地。从而导致了海南岛的早期构造运动,而海南岛后期的构造运动则主要是受南海海底扩张的影响。海南地体运动规律的阐明对于了解北部湾油气盆地的形成演化有重要的理论和实际意义。     

Exciton Seebeck in Molecular Systems

Various applications relevant to the exciton dynamics,such as the organic solar cell,the large-area organic light-emitting diodes and the thermoelectricity,are operating under temperature gradient.The potential abnormal behavior of the exicton dynamics driven by the temperature difference may affect the efficiency and performance of the corresponding devices.In the above situations,the exciton dynamics under temperature difference is mixed with     

Achieving Unusual States of Matter Under High Pressure

The elongation method,originally proposed by Imamura was further developed for many years in our group.As a method towards O(N)with high efficiency and high accuracy for any dimensional systems.This treatment designed for one-dimensional(ID)polymers is now available for three-dimensional(3D)systems,but geometry optimization is now possible only for 1D-systems.As an approach toward post-Hartree-Fock,it was also extended to     

《Chinese Science Bulletin》SUBJECT INDEX TO VOLUME 59(2014)

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An on-line scaling method for improving scalability of a database cluster

The explosive growth of the Internet and database applications has driven database to be more scalable and available, and able to support on-line scaling without interrupting service. To support more client's queries without downtime and degrading the response time, more nodes have to be scaled up while the database is running. This paper presents the overview of scalable and available database that satisfies the above characteristics. And we propose a novel on-line scaling method. Our method improves the existing on-line scaling method for fast response time and higher throughputs. Our proposed method reduces unnecessary network use, i.e. , we decrease the number of data copy by reusing the backup data. Also, our on-line scaling operation can be processed parallel by selecting adequate nodes as new node. Our performance study shows that our method results in significant reduction in data copy time.     

An improved R-tree based on childnode''s probability

R-Tree is a good structure for spatial searching. But in this indexing structure,either the sequence of nodes in the same level or sequence of traveling these nodes when queries are made is random. Since the possibility that the object appears in different MBR which have the same parents node is different, if we make the subnode who has the most possibility be traveled first, the time cost will be decreased in most of the cases. In some case, the possibility of a point belong to a rectangle will shows direct proportion with the size of the rectangle. But this conclusion is based on an assumption that the objects are symmetrically distributing in the area and this assumption is not always coming into existence. Now we found a more direct parameter to scale the possibility and made a little change on the structure of R-tree, to increase the possibility of founding the satisfying answer in the front sub trees. We names this structure probability based arranged R-tree (PBAR-tree).     

An Index mechanism for multi-scale view in spatial databases

There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.     

Integrating GIS Web services based on mediating architecture

The geographic information service is enabled by the advancements in general Web service technology and the focused efforts of the OGC in defining XML-based Web GIS service. Based on these models, this paper addresses the issue of services chaining,the process of combining or pipelining results from several interoperable GIS Web Services to create a customized solution. This paper presents a mediated chaining architecture in which a specific service takes responsibility for performing the process that describes a service chain. We designed the Spatial Information Process Language (SIPL) for dynamic modeling and describing the service chain, also a prototype of the Spatial Information Process Execution Engine (SIPEE) is implemented for executing processes written in SIPL. Discussion of measures to improve the functionality and performance of such system will be included.