历史遗址类旅游地的生命周期研究——以美国14家历史遗址公园为例     

杨小露  张红  张春晖 《地理科学进展》2019,38(6):918-929

实证研究中旅游地生命周期理论的运用潜力备受质疑。论文选取美国14家国家历史遗址公园为例,采用旅游研究中较少使用的四参数Logistic模型结合一次函数、二次函数、三次函数、高斯多峰分析法拟合旅游地的生命周期。研究发现：四参数Logistic模型结合一次函数、二次函数、三次函数能较好地拟合旅游地的生命周期;利用四参数Logistic曲线的上弯点、拐点、下弯点能定量的划分出旅游地的起步探索、发展、巩固、停滞阶段,一次函数、二次函数、三次函数能拟合旅游地的衰退或复兴阶段,这回答了学者们对生命周期阶段难以定量划分的质疑。根据旅游地停滞期之后的发展趋势还能归纳出该类旅游地的生命周期类型;高斯多峰分析法将旅游地的生命周期拟合成一个个波动的高斯峰,更大程度上保留了旅游地演进的波动特征;将高斯多峰分析法与四参数Logistic模型结合起来,不仅能定量划分旅游地的生命周期阶段,还能准确地描述在生命周期阶段内的波动情况,甚至分析各生命周期阶段对整个生命周期的影响和作用。  相似文献   

不同结构林带防风效能风洞模拟     

李晓烨  王克俭  谷建才  刘启国  崔严 《中国沙漠》2019,39(6):118-125

防风林带结构是影响防风效能的主要因素。建立不同宽度、不同株行距林带防风效能与林带后距离之间的统计模型，可以为防风林建设提供指导性意见。通过风洞实验，在11 m·s^-1风速下，对4种宽度、5种株行距林带的背风面0~10H（H为林带高度）的风速进行测定，采用曲线参数估计法、傅立叶模型、SSF模型（Sum of Sin Functions），构建了不同结构林带防风效能与林带后距离间的统计模型。结果表明：傅立叶模型拟合不同宽度林带的防风效能与林带后距离的关系效果最优，可决系数（R²）均在98%以上；SSF模型拟合不同株行距林带的防风效能与林带后距离的关系效果最优（R²>0.98）。根据构建的统计模型，风速为11 m·s^-1左右时，林带宽度8 m（两行一带）的防风林的防风效能存在明显优势；5种株行距的林带中，株行距为8 m×8 m的防风林带本试验条件下防风效果最好。  相似文献   

Estimation of Grassland Production in Central and Eastern Mongolia from 2006 to 2015 via Remote Sensing     

LI Ge  WANG Juanle  WANG Yanjie  WEI Haishuo 《资源与生态学报(英文版)》2019,10(6):676-684

Mongolia is an important part of the Belt and Road Initiative “China-Mongolia-Russia Economic Corridor” and a region that has been severely affected by global climate change. Changes in grassland production have had a profound impact on the sustainable development of the region. Our study explored an optimal model for estimating grassland production in Mongolia and discovered its temporal and spatial distributions. Three estimation models were established using a statistical analysis method based on EVI, MSAVI, NDVI, and PsnNet from Moderate Resolution Imaging Spectroradiometer (MODIS) remote sensing data and measured data. A model evaluation and accuracy comparison showed that an exponential model based on MSAVI was the best simulation (model accuracy 78%). This was selected to estimate the grassland production in central and eastern Mongolia from 2006 to 2015. The results show that the grassland production in the study area had a significantly fluctuating trend for the decade study; a slight overall increasing trend was observed. For the first five years, the grassland production decreased slowly, whereas in the latter five years, significant fluctuations were observed. The grassland production (per unit yield) gradually increased from the southwest to northeast. In most provinces of the study area, the production was above 1000 kg ha ^-1, with the largest production in Hentiy, at 3944.35 kg ha ^-1. The grassland production (total yield) varied greatly among the provinces, with Kent showing the highest production, 2341.76×10 ⁴ t. Results also indicate that the trend in grassland production along the China-Mongolia railway was generally consistent with that of the six provinces studied.  相似文献   

函数模型与随机模型双约束的GPS-InSAR数据融合方法建立三维形变场     

马艳鸽  赵丽华  张盼盼  吕佳凝 《大地测量与地球动力学》2019,39(11):1112-1117

针对InSAR技术研究地表三维形变时监测信息不足的问题，以GPS监测信息为先验信息，建立附有随机模型约束的地表三维形变模型。考虑到SAR卫星极轨方式运行导致LOS向观测量对南北向形变不敏感的问题，以GPS南北向形变观测值作为强约束，构建三维形变解算的函数约束条件。模拟数据与西安地区实测数据的计算结果表明，基于随机模型与函数模型共同约束的地表三维形变参数最小二乘解的精度优于仅有函数模型约束或仅有随机模型约束及无任何约束的参数解精度。  相似文献   

Facies and sequence stratigraphic architecture of the Mural Limestone (Albian), Arizona: Carbonate response to global and local factors and implications for reservoir characterization     

Rachel Aisner-Williams  Charles Kerans 《Sedimentology》2020,67(7):3735-3768

This study documents the detailed facies and sequence stratigraphic architecture of a multi-cyclic patch-reef and its associated ramp interior facies that formed during Oceanic Anoxic Event 1b in the Mural Limestone, Arizona, USA. Ramp interior facies are comprised of bedded wackestone/packstone, rudist build-up and coral–algal patch-reef facies located north of Bisbee, Arizona, at the Grassy Hill locality. The larger multi-cyclic patch-reef that developed coevally ca 5 km to the south of Grassy Hill consists of a high-angle windward margin with a narrow ca 70 m long reef frame containing vertically zonated Microsolena, Actinastrea, diverse branching coral and rudist assemblages, and an 870 m long low-angle leeward margin comprised of reef debris rudstone and grainstone shoal facies. Similar reef geomorphology and orientation is documented across the Gulf of Mexico and reflects the shelf-wide north to north-east-trending prevailing wind and current energies. Controls affecting reef formation and growth patterns include changes in accommodation space associated with low-amplitude global sea-level rise and regional thermotectonic subsidence, local accommodation space and nutrient fluctuations associated with the inner shelf depositional setting within a humid and siliciclastic-rich environment. Four aggradational to retrogradational high-frequency sequences are documented in Arizona: High-frequency sequences 1 and 2 represent the first pulse of patch-reef development in an overall second-order marine transgression over the Sonora/Bisbee Shelf. These sequences correlate to δ¹³C signatures associated with Oceanic Anoxic Event 1b across the Gulf of Mexico and suggest that carbonate reefs persisted on the ramp interior during this time. High-frequency sequences 3 and 4 record a second brief transgression and backstepping of reef facies followed by the final regression of shallow shelf carbonates that correlates to more robust patch-reef development in Sonora, Mexico. The patch-reef at Paul Spur is an excellent outcrop analogue for productive patch-reefs in the Maverick Basin (Comanche Shelf) of Texas. Detailed facies mapping of this outcrop analogue shows that the greatest reservoir potential is contained within the backreef grainstone shoals where primary porosity of up to 15% is observed.  相似文献   

Crack nucleation in saturated porous media     

Luc Dormieux  Eric Lemarchand  Thomas Carlioz  Laurent Jeannin 《国际地质力学数值与分析法杂志》2020,44(5):553-574

Crack nucleation has been the subject of important contributions in the last two last decades. However, it seems that few attention has been granted to the case of saturated porous media. This is the question addressed in the present paper which is devoted to nucleation in traction mode. From a physical point of view, nucleation is a sudden phenomenon, so that the material response is both adiabatic and undrained. In the spirit of the variational approach, the nucleated crack is viewed as the final state of a region of space in which the material undergoes a full damage process. In traction mode, the opening of a saturated crack in undrained condition induces a drop of fluid pressure. In case of low fluid compressibility, the presence of the fluid delays the brittle failure usually associated with nucleation, as long as the fluid pressure remains above the saturation vapor pressure. Nucleation is therefore possible only if a partial vaporization of the fluid takes place.  相似文献   

桂西北林旺金矿床构造控矿规律及成矿模式探讨     

张知春 《地质与勘探》2020,56(2):277-287

桂西北林旺金矿是近年来右江盆地新发现的卡林型金矿,位于乐业碳酸盐台地边缘乐业-浪全同生断裂带上。通过对矿区进行野外调查、岩矿鉴定并结合勘探成果进行综合研究,发现I号矿体群与断裂、褶皱的时空联系具有构造分带的特征,以F1断层为界,上盘褶皱鞍部发育石英杂砂岩夹粉砂质泥岩矿体,矿体近F1断层破碎带部位发育破碎的硅化构造岩带,F1下盘近破碎带部位发育强烈劈理化、炭化粉砂质泥岩带,指示矿区在印支期挤压过程中,石英杂砂岩顺着先存构造薄弱面以泥岩层为滑动系统,往上部逆冲并逐渐发生褶皱,产生许多张裂隙,成为成矿流体富集的场所。林旺金矿床是层滑-褶皱构造体系与成矿流体耦合作用的产物,分析了矿床构造成矿规律,提出了以层滑-褶皱运动机制为基础的成矿模式以及成矿远景。  相似文献   

水资源约束下的河西走廊城市经济脆弱性时空演变及其影响因素     

张戬  陈佳  黄馨  王子侨 《中国沙漠》2019,39(1):203-211

城市经济脆弱性作为当前脆弱性研究中的重要领域，为人-地系统耦合研究提供了新的视角，并为城市可持续健康发展提供有益的决策支持和管理方法。依据城市经济脆弱性内涵，基于暴露度、敏感性、适应能力构建了城市经济脆弱性评价指标体系，运用熵权TOPSIS法评价河西走廊地区及区域内五市的城市经济脆弱性，并采用障碍度模型识别影响区域城市经济脆弱性变化的因素。结果显示：（1）2006—2015年，河西走廊地区城市经济脆弱性呈现出先曲折下降（2006—2011年）再波动上升趋势（2012—2015年）；（2）河西走廊地区的城市经济脆弱性具有明显的空间特征，经历了东西高、中部低到整体较高的演变过程；（3）阻碍河西走廊地区城市经济脆弱性降低的障碍因子由适应能力逐步转变为暴露度。针对河西走廊地区各市主要障碍因子，提出针对性优化措施。  相似文献   

辽宁沿海地区海洋经济增长质量空间特征及影响要素     

李博  田闯  史钊源  韩增林 《地理科学进展》2019,38(7):1080-1092

在海洋经济质量转型之期,基于“认知—评价—建构—优化”理念,界定海洋经济增长质量内涵,通过中心-引力模型评价分析2000—2014年辽宁沿海地区海洋经济增长质量空间特征,构建了海洋经济增长质量模型,识别影响其空间特征的相关要素,并根据要素作用程度提出优化建议。研究发现：① 辽宁沿海地区海洋经济增长质量呈“核心—圈层”结构,形成以大连为“领头雁”的雁阵式相互继起模式;“钻石型”引力流结构促成辽宁沿海地区集中化连片发展格局;② 海洋经济增长质量空间特征主要受空间集聚效应影响,海洋资本、海洋基建和海洋产业结构成为推动海洋经济增长质量循环引力流的顺流机制,其中海洋产业结构成为影响辽宁海洋经济增长质量圈层空间集聚效应的关键流;海洋人才成为制约海洋经济增长质量循环引力流的逆流机制;③ 通过路径作用程度的象限划分,提出强化大连中心地职能,针对腹地城市定位及资源禀赋条件提出调控措施,推进沿海区域协调与一体化进程。  相似文献   

Analog simulation of urban construction land supply and demand in Chang-Zhu-Tan Urban Agglomeration based on land intensive use     

Xiong  Ying  Chen  Yun  Peng  Fen  Li  Jingzhi  Yan  Xiaojing 《地理学报(英文版)》2019,29(8):1346-1362

Journal of Geographical Sciences - Urban land intensive use is an important indicator in harmonizing the relationship between land supply and demand. The system dynamics (SD) can be used to...  相似文献