河南省耕地变化及其人文驱动力研究

根据河南省历年耕地及其相关统计数据,对河南省耕地时间(数量和质量)、空间变化和驱动因子进行了深入分析.结果显示:57a期间,耕地总量自1954年最高峰9.06万km²以来,整体上呈逐年减少趋势;1984~2005年耕地标准面积和标准系数均呈现波动增长趋势;耕地空间分布重心整体上向东南方向变化;采用主成分分析方法,得出影响河南省耕地变化的驱动力归纳为农业科技进步、社会发展水平和经济发展水平.     

基于STIRPAT模型的陕西省耕地面积变化社会经济驱动力分析

近年来,耕地面积变化的人文驱动力研究成为土地利用与土地覆盖变化(LUCC)领域研究的热点.以陕西省1978-2010年耕地面积数据及其相关社会经济影响因素时间序列数据为例,通过主成分分析法、逐步回归法筛选出影响陕西省耕地面积变化的主要影响因素.然后运用STIRPAT模型,分析经以上方法筛选出的主要影响因素即城镇化率、人均生产总值、公路里程、社会消费品总额对于陕西省耕地面积变化的影响.结果表明:人均生产总值的提高是导致陕西省耕地面积减少的主要原因,社会消费品总额的增加对于陕西省耕地面积的减少也发挥着重要的作用.而交通条件的完善是促进陕西省耕地面积增加的主要驱动力.同时,城市化率的提高对抑制耕地面积的减少起到了一定的促进作用.据此,研究认为缓解陕西省耕地面积减少的压力可以从进一步提高城镇化率、完善交通设施,调整优化产业结构,转变经济增长方式等方面入手.     

Combining local pressure and temperature measurements during bread baking: insights into crust properties and alveolar structure of crumb

Improvements in both the miniaturisation and heat compensation of pressure transducers made it possible to measure pressures as low as 5 kPa inside bread dough during baking (ΔT = 80 °C). Additional calibration was found to be necessary to decrease it below 0.18 kPa according to the variations in temperature encountered during baking. Two probes with both a thermocouple and a miniature pressure transducer were used to reveal pressure gradients inside bread dough during baking and post-cooling. During baking, increase in pressure (up to 1.1 kPa) was mainly attributed to the mechanical restrictions exerted on the dough by the stiffened surface layers. Pressure build-up due to the stiffening of bubble walls could not be detected. Various effects of the rupture in the bubble walls are reported. Sudden falls in pressure observed up to 70 °C were attributed to the bubble coalescence phenomenon. Evidence of an open porous structure was provided by the balance in pressure through the dough before the end of baking and the almost simultaneous lowering of pressure (−0.15 kPa) throughout the crumb during cooling. The slight lowering of pressure during post-cooling was also evidence of lower permeability of the crust compared to the crumb.     

扎龙湿地土地利用变化及驱动力分析

基于1995年、2000年和2004年3期LandsatTM遥感影像数据,运用RS、GIS及景观生态学方法,对研究区土地利用与景观格局动态变化进行分析,运用逐步回归分析法和主成分分析法,探讨扎龙湿地土地利用与土地覆盖驱动力机制,研究结果表明:沼泽向草地转化的趋势较明显,沼泽地不断退化为草地,草地再进一步退化为盐碱地,说明湿地缺水及沼泽地的退化问题比较严重.研究时段内耕地、沼泽和草地的斑块数、斑块密度、边界密度和形状指数均呈现持续增长的趋势.前一时段(1995-2000年),景观多样性和景观均匀度指数减小,景观优势度增大;后一时段(2000-2004年),变化趋势呈相反态势,作为研究区的基质景观,沼泽地面积不断减少,导致景观的破碎化程度进一步加剧,土地利用趋于多样化和均匀化,景观格局趋向复杂化.     

基于乡村旅游驱动的苏北旅游竞争力提升研究

通过分析国内外乡村旅游业发展的典型案例,找出驱动乡村旅游业发展的动力源以及驱动力,并构建目的地供给侧视角下的驱动乡村旅游业发展的机制。根据驱动机制,结合苏北乡村旅游业发展实际情况,诊断苏北乡村旅游业发展驱动力以及驱动机制存在的问题,提出苏北乡村旅游发展对策:改革供给侧驱动源主体,提升驱动源动力水平;挖掘乡村旅游资源特色,提升其旅游吸引力;完善管理制度,提升乡村旅游服务拉力;树立整体营销理念,提升乡村旅游营销能力。     

盘龙河流域（龙潭寨水文站以上段）土地利用变化及驱动力分析

选取盘龙河流域（龙潭寨水文站以上段）作为研究区域,根据1990、1999年遥感影像,利用RS、GIS技术,分析研究区1990、1999年土地利用现状,以及9年间土地利用的空间变化特征。同时结合社会经济方面的资料,采用定性分析方法剖析土地利用变化驱动力,揭示区域土地利用变化与驱动力的关系,并为区域利用土地资源提供合理性建议。     

中国退耕还林(草)驱动力的多尺度分析

退耕还林(草)作为当前生态建设的重要内容,其实质是通过调整土地利用方式,恢复重建地表自然覆盖,建立生态安全条件下的土地利用/覆盖格局。研究不同尺度下退耕还林(草)的驱动力,可以为构造典型区域土地可持续利用结构与优化模式提供依据。该文从国家-省区-县域-农户尺度上分析了中国退耕还林(草)的驱动力,国家尺度上驱动力是生态环境安全、粮食结构调整和西部大开发,以生态安全为主;省区驱动力分为产业结构调整、水源地保护、防洪、保护三峡工程、减少入黄泥沙和防治风蚀沙化6种类型,经济状况居于主导地位;县域驱动力归纳为12种类型,以产业结构调整、发展主导产业、增加农民收入和改善农业生产条件为主;农户的退耕还林(草)是国家政策满足农户需求,个体利益最佳化为主要驱动力。     

基于RS和GIS的盐城海岸带湿地景观格局变化及其驱动力研究

在遥感和GIS技术支持下,以江苏盐城海岸带TM影像为主要数据源,研究了江苏盐城海岸带湿地近15a来景观格局特征及其动态变化情况,探讨了其景观变化的主要驱动因素。结果表明,1992～2006年,盐城海岸带自然湿地呈萎缩状态;湿地斑块数量亦在减少,由1992年的748个减少到2006年的466个;湿地景观多样性指数和均匀度指数呈下降趋势,分别由1992年的1．8085和0．8231降至2006年的1．5806和0．7194,而优势度呈上升趋势,由1992年的0．3887增长为2006年的0．6165。在盐城海岸带,大规模围垦养殖和米草的入侵是其海岸湿地景观变化的重要因素。     

The integration of planted and natural forests in a regional landscape

The 10,700 km² region of northwestern Oregon, USA, is dominated by mountainous forested landscapes fringed by agricultural lands and rapidly expanding urban areas. The Douglas-fir/western-hemlock trees, admixed with other species, in the mild, moist regional climate with rich soils are among the most highly productive of temperate forests. Timber harvest has been the dominant land use for much of this century. Many current forest stands are planted, and have the potentials to be managed and shaped for a variety of traditional and evolving forestry objectives. The ages, resilience and productivity of these forests and mosaics of land ownerships permit a variety of future scenarios of forested landscapes, constrained largely by capacities of social organizations to plan and execute management for desired future conditions. This revised version was published online in June 2006 with corrections to the Cover Date.     

Wind Tunnel Test for Section Model of Caiyuanbai Bridge Over Yangtse River

With the development of modern construction technique and the application of new material,arch bridges which progress towards small rigidity,long span and light weight,what's more is that long span bridge's rigidity under construction is much less than that in use stage.So it is very necessary to study the aerodynamic characteristics of long span bridge.The regularity of the three dimensional static component forces coefficient varying with attack angle and the girder's flutter properties of Caiyuanbai Bridge over Yangtse River are investigated with segmental molding's static wind-tunnel test and segmental molding's dynamic wind-tunnel test.Eight derivatives of the girder are also identified from the segmental molding's dynamic wind-tunnel test.Finally the assessment to wind resistant properties of the bridge is given based on detailed analysis of the test results.The conclusion which gets from analysis can provide an suggestion to design and construction this kind bridge.