鄂尔多斯盆地大牛地地区致密砂岩石英溶解作用及其对优质储集层的影响

储集层孔隙成因机制是致密砂岩储集层评价和预测必须解决的基本问题。本文以储集层微观分析为基础,对鄂尔多斯盆地大牛地气田石炭-二叠系致密砂岩储集层孔隙成因类型及其和优质储集层成因的关系进行了研究。结果表明,研究区致密砂岩储集层中碎屑石英颗粒存在明显的直接溶解现象,并形成了以石英溶解为主的储集空间类型,这种石英溶解是碱性成岩环境作用的结果,致密砂岩储集层的发育程度仍然和孔隙度以及组分的溶解作用有密切关系,碱不稳定矿物的溶蚀量一般为1%~23%,石英溶解型孔隙对储集层孔隙的贡献率一般可以达到60%~90%,碱溶蚀量达到5%以上时有利于优质储集层的形成;石英溶解作用较强的位置主要是颗粒边部的粒间孔隙周围,这种类型的溶解形成于储集层经历较强的压实成岩改造之后,所形成的溶解孔隙在后期的持续性压实过程中损失程度较低;石英溶解作用的强弱决定了储集层物性的最终发育程度以及优质储集层的形成。     

Thermal analysis of energy piles in sand

The present work investigates the behaviour of geothermal energy piles in sand subjected to thermal loading and the resulting soil-structure interaction, numerically using the finite element software Abaqus and user-defined material subroutines for soil. The stress-strain response of sand has been simulated using CASM constitutive model based on critical-state soil mechanics. Detailed parametric sensitivity studies have been carried out to understand the effects of different end conditions of the pile, relative densities of the soil, coefficients of lateral earth pressure of the ground, lengths and diameters of the pile, thermal loads, coefficients of friction at the pile-soil interface, critical-state friction angles of soil, thermal conductivity of soil, specific heat of soil and thermal conductivity of the pile on the stress response of soil, deformation of the pile and soil, and strains in the pile. The results show that negative shear stress is generated in the soil at the pile-soil interface. In the pile with both ends restrained the lateral earth pressure coefficient in soil increases due to high radial strain generation. Moreover, the lateral earth pressure coefficient in soil increases with the increase in the thermal load, the coefficient of friction at the pile-soil interface and the critical-state friction angle of the soil.     

长江上游安宁河流域植被生长变化对气候条件的响应

为探讨安宁河流域植被演变趋势及其与气候的相互作用,基于2001—2008年MODIS图像、降水量和气温数据,采用回归分析和相关分析等方法计算了安宁河流域降水、气温和归一化差值植被指数(normalized difference vegetation index,NDVI)在时间和空间上的变化情况,并对安宁河流域植被生长变化对气候条件的响应机制进行了探讨。结果表明:NDVI变化和气温、降水呈正相关;降水量和气温等气候因子的变动会直接反映在植被长势上,其中降水对安宁河流域植被生长的影响更为显著;植被长势与气温和降水存在一定的时间滞后性。     

GIS-based cost distance modelling to support strategic maritime search and rescue planning: A feasibility study

Geographic information system (GIS) based methodologies are widely used to various problems. However, its potential for application to strategic maritime search and rescue (SAR) planning remains largely unexplored. To investigate the applicability of GIS-based tools to this problem, this paper presents an approach to evaluate accessibility and response times in a sea area. Such information aids to objectify the response effectiveness of a SAR system, which is important for rational resource allocation. The presented methodology accounts for the main characteristics of maritime response, namely spatial accessibility, capabilities of search and rescue units (SRUs) and prevailing wave conditions, which affect the attainable SRU speeds. An application to the Finnish areas of the Gulf of Finland is shown. Despite the existence of some difficulties with currently available tools (e.g. accurate and user-friendly spatial wave models and challenges with using raster-based methods in topologically complex areas) and limitations in knowledge (e.g. the SRU capabilities in actual operations), the results indicate that the methodology provides good opportunities for enhancing maritime decision making.     

Decadal‐Scale Changes of the Ödenwinkelkees,Central Austria,Suggest Increasing Control of Topography and Evolution Towards Steady State

Small mountain glaciers have short mass balance response times to climate change and are consequently very important for short‐term contributions to sea level. However, a distinct research and knowledge gap exists between (1) wider regional studies that produce overview patterns and trends in glacier changes, and (2) in situ local scale studies that emphasise spatial heterogeneity and complexity in glacier responses to climate. This study of a small glacier in central Austria presents a spatiotemporally detailed analysis of changes in glacier geometry and changes in glaciological behaviour. It integrates geomorphological surveys, historical maps, aerial photographs, airborne LiDAR data, ground‐based differential global positioning surveys and Ground Penetrating Radar surveys to produce three‐dimensional glacier geometry at 13 time increments spanning from 1850 to 2013. Glacier length, area and volume parameters all generally showed reductions with time. The glacier equilibrium line altitude increased by 90 m between 1850 and 2008. Calculations of the mean bed shear stress rapidly approaching less than 100 kPA, of the volume–area ratio fast approaching 1.458, and comparison of the geometric reconstructions with a 1D theoretical model could together be interpreted to suggest evolution of the glacier geometry towards steady state. If the present linear trend in declining ice volume continues, then the Ödenwinkelkees will disappear by the year 2040, but we conceptualise that non‐linear effects of bed overdeepenings on ice dynamics, of supraglacial debris cover on the surface energy balance, and of local topographically driven controls, namely wind‐redistributed snow deposition, avalanching and solar shading, will become proportionally more important factors in the glacier net balance.     

长江三角洲地区污染密集型产业转移及驱动机理

污染密集型产业转移及影响机理研究已成为区域可持续发展的研究热点之一。利用长江三角洲地区2000-2010年面板数据,运用Arc GIS空间分析工具,探讨污染密集型产业的时空格局演变特征及转移规律,构建计量学模型,定量地揭示其转移的驱动机理。结果表明:1近十年来,长江三角洲地区的污染密集型产业具有空间转移特征,转移方向基本符合沪宁—沪杭甬交通线,呈现由中心城市到外围城市、由集中到分散转移态势;2污染密集型产业转移主要受到外向度和劳动力成本拉动,而与经济发展水平呈负相关,环境规制、产业结构、创新能力均产生重要推动作用。3长江三角洲地区经济发展目前已逐渐摆脱依赖污染密集型产业的迹象,但污染密集型产业区位仍未发生根本性改变。     

农村居民点动态演变及驱动机制研究——以江苏省宜兴市为例

选取宜兴市为研究区,在GIS和RS技术的支撑下,对农村居民点用地的规模变化和空间分布进行分析,对引起农村居民点用地变化的驱动因素进行研究。结果表明:1农村居民点用地整体呈下降趋势,变化速度逐年减慢,主要新增来源是农用地,主要转移去向是城镇建设用地;2在地形平坦、距离水源和农用地较近的地区,农村居民点分布密集;3经济发展、人口减少、交通改善和城市化水平提高是影响农村居民点变化的主要驱动因素。     

农业产业集群的演化阶段与形成机理分析——以宁夏中宁县枸杞加工产业为例

在总结前人研究基础上,借鉴国内外农业产业集群研究的相关理论,以宁夏中宁县枸杞加工产业集群为例,运用企业资料和半结构式访谈法,探讨了农业产业集群的演化阶段和形成机理。研究发现:(1)中宁县枸杞加工产业集群遵循农业产业集群演化的一般发展规律,经历了培育期、成长期及形成期,在不同的发展阶段集群表现出不同特征。(2)地区独特的资源禀赋、历史文化、宏观制度等偶然因素激发集群最初形成,地理临近导致的集聚效应促使集群逐步成长,收益递增引发的路径依赖则进一步促进集群的形成。(3)由于收益递增、路径依赖及企业惯例,集群在演化过程中可能会陷入低效率的锁定状态。为了摆脱这种困境,首先,政府应推动企业间网络合作强度及知识流动,提升集群创新能力;其次,要加强集群与区外联系实现集群在全球价值链上的嵌入,保持集群持续的竞争力。研究结果可为农业产业集群形成及机理研究提供借鉴,为宁夏枸杞加工产业发展提供指导。     

历史文化名城改造中城市更新概念的衍生、想象和认知局限性——以佛山岭南天地“三旧”改造为案例

以佛山市“岭南天地”(祖庙-东华里历史文化街区)的“三旧”改造为案例,讨论历史文化名城核心区改造中城市更新概念的衍生、想象及认知局限性.尤其侧重于概念运用在历史文化名城老城核心区更新中的作用、价值及其在更新实践中的推动或限制因素.研究显示,“三旧”改造概念作为城市更新理念与佛山城市旧区改造的现实问题相互结合而衍生的“应景”产物,在运用中凝练了更新主体(地方政府)对旧区改造发展的愿望、想象和认知倾向.这使得“三旧”改造概念在历史文化名城城市更新中的应用存在部分的局限性.另一方面,“三旧”改造发展模式及其想象展望也可能只是地方政府及开发商谋求城市、产业发展和城市综合竞争力提升的一种手段.此外,研究显示,“三旧”改造概念只被地方政府和投资人用作组织与寻求他们各自关注点的一种达到目的的手段或技术,从本质上来说,这个概念对他们的吸引力在于与之相关联的资源,以及一种供使用、阐释、替换的语言.至于这个概念对历史文化名城城市更新的实用性,则似乎关注不够.     

Discussion on “The action of elemental sulfur plus water on 1-octene at low temperatures” by Said-Ahmad et al. (Organic Geochemistry 59, 82–86)

A recent article (Said-Ahmad, W., Amrani, A., Aizenshtat, Z., 2013. The action of elemental sulfur plus water on 1-octene at low temperatures. Organic Geochemistry 59, 82–86) is commented on in this discussion. Radical mechanisms proposed by Said-Ahmad et al. (2013) for the formation of sulfurized and oxidized organic compounds in experiments involving elemental sulfur and 1-octene under aqueous conditions, aimed at investigating the interaction of organic matter and sulfur compounds under geological conditions, are not compatible with their experimental results and other studies. In addition, results from the experiments aimed at demonstrating the role of HO radicals in the formation of oxidized organic compounds were incorrectly interpreted by the authors. In this discussion, alternative mechanisms for the formation of the sulfurized and oxygenated products reported by Said-Ahmad et al. (2013) are proposed.