吉林省村域尺度下居民点空间分布特征及优化重组模式

乡村聚落的空间优化与重构是提高土地资源利用效率,改善农村生产生活条件,促进乡村可持续发展的重要手段。以吉林省为例,采用核密度估计方法和景观形状指数分析了农村居民点空间分布特征,基于农户调查数据估算了吉林省不同区域的农村宅基地闲置情况,将农村居民点长期存在的“破碎化”和日益突出的“空心化”相结合,提出了在行政村尺度下农村居民点优化重组的“整小填大”新模式。结果表明：① 吉林省农村居民点规模小且零散分布,尤其中部呈破碎化分布,形态不规则,具有较大的整治潜力;② 吉林省农村宅基地平均闲置率为18.32%,西部地区最高（24.48%）,分别高于东部和中部地区约6%和12%;③“整小填大”模式可使农村居民点数量减少44.6%,增加有效耕地面积1 046.66 km²。     

空间构件形位检测方法与技术进展

精密工程与工业测量技术应用领域拓展及其与工业计量测试技术的交叉融合,衍生出"空间构件形位检测"技术、方法与系统。本文详细论述了"空间构件"与"形位检测"的定义及范畴,依测量原理将大尺寸空间构件形位检测技术归纳为正交系测量系统、空间支导线测量系统、三角法测量系统和球坐标法测量系统等,综述了各类测量系统和软件的技术进展,分析指出了狭长或超大空间、恶劣环境、目标动态变化等条件下的形位检测难题。     

动力相似法在一次大暴雨过程中的应用

利用NCEP再分析资料、ECWMF预报风场和历史降水量资料,分别采用前人提出的相似量和本文改进的相似量进行动力相似选择试验。结果表明:改进后的相似量的相似选择效果最好。对于南充2012年7月4日区域大暴雨过程,用改进相似量筛选出与此次过程最相似的历史个例,进行对比分析后,发现最相似个例风场与预报风场在形状、强度和影响系统空间配置都很相似,降水实况接近。表明最相似个例的风场和降水资料对该次大暴雨过程的降水量级、落区预报有较高的参考和指示意义。     

Performance of shape indices and classification schemes for characterising perceptual shape complexity of building footprints in GIS

Shape characterisation is important in many fields dealing with spatial data. For this purpose, numerous shape analysis and recognition methods with different degrees of complexity have so far been developed. Among them, relatively simple indices are widely used in spatial applications, but their performance has not been investigated sufficiently, particularly for building footprints (BFs). Therefore, this article focuses on BF shape characterisation with shape indices and classification schemes in a GIS environment. This study consists of four phases. In the first phase, the criteria for BF shape complexity were identified, and accordingly, benchmark data was constructed by human experts in three shape complexity categories. In the second phase, 18 shape indices were selected from the literature and automatically computed in GIS. The performance of these indices was then statistically assessed with histograms, correlation matrix and boxplots, and consequently four indices were found to be appropriate for further investigation. In the third phase, two new indices (Equivalent Rectangular index and Roughness index) were proposed with the objective to measure some BF shape characteristics more efficiently. The proposed indices also were found to be appropriate with the same statistical assessment procedures. In the final phase, BF shape complexity categories were created with the pairs of six appropriate indices and four choropleth mapping classification schemes (equal intervals, natural break, standard deviation, and custom) in GIS. The performance of the index–scheme pairs was assessed against the benchmark data. The findings demonstrated that both new indices and two of the selected indices (Convexity and Rectangularity) delivered higher performance. The custom classification scheme was found more ideal to reveal absolute shape complexity with the index value ranges derived from the boxplots while the other classification schemes were more appropriate to reveal relative shape complexity.     

基于分类与形态综合的高分辨率影像建筑物提取方法研究

本文提出了一种基于分类和形态综合的高分辨率影像建筑物提取方法。主要研究的是基于高分辨率影像多尺度分割的面向对象人工地物分类方法,并以此为基础提取房屋,实现房屋位置、范围的初步自动化提取。最后,对提取的地物图斑的精确边界利用Hough变换提取直线边缘轮廓线,并以此为基础进行轮廓拟合和制图综合,从而得到规则的、方形组合的建筑物形状信息。     

Single phase water flow through rock fractures

Flow analysis plays a major role in various geotechnical applications, and the understanding of flow mechanisms is essential for the development of a hydro-mechanical flow model suitable for underground excavations in rock. Discrete flow analysis through discontinuities is reviewed including empirical and analytical flow models. The influence of external loading on joint deformation and single-phase flow show that the surface roughness and aperture size are the prime factors influencing flow rate. Nevertheless, the idealization of natural fractures as smooth parallel plate joints is still followed in many numerical models, because of the simplicity of the cubic law when applied to fracture networks. A numerical study of water flow through a network of joints employing Universal Distinct Element Code (UDEC) is used to quantify the effects of joint orientation and external stress acting on idealized joints.It is found that, for the same joint spacing, the flow rate into an excavation depends on the boundary block size (A_b) relative to the excavation size (A_e). The inflow becomes excessive if A_b/A_e is less than 4, but becomes very small if A_b/A_e exceeds 8.     

地下深部灰岩岩石特性的单孔雷达反射研究

灰岩中岩溶和裂隙发育规律研究是研究陷落柱发育规律的基础,研究结果表明在单孔雷达反射图像上岩溶和裂隙反映清晰,单孔雷达反射法用于灰岩岩石特性研究效果显著,该研究成果填补了国内灰岩岩石特性的单孔雷达反射研究的空白,为地下深处灰岩岩石特性高分辨率探测开辟了新途径。     

新疆乌鲁木齐台地电阻率变化及震兆特征

以乌鲁木齐地电阻率观测资料为依据,在展示其变化特征的基础上,对该地电阻率资料异常变化与近区中强地震及部分远区的大地震之间的关系进行了归纳、分析与讨论。对地电阻率前兆异常形态与地震之间的关系进行了探讨。     

顺应式海洋平台慢漂运动物理模型试验研究

为研究顺应式海洋平台慢漂运动的影响因素,以截断圆柱和漂浮方箱为例进行了不规则波作用下的慢漂运动模型试验。测量了不同系泊刚度条件下的漂浮方箱以及相同系泊刚度条件下的截断圆柱和漂浮方箱在静水中自由衰减运动和在不规则波中的运动响应,并将运动响应分解成一阶波频运动响应和二阶低频运动响应,分析了系泊刚度和浮体形状对浮体运动的影响。通过物理模型试验发现了系泊刚度及浮体形状对顺应式系泊浮体一阶运动标准差和二阶低频运动平均漂移值和标准差的关系。结果表明由于顺应式浮体的固有周期远离波浪谱峰周期时,系泊刚度以及浮体形状对慢漂运动的一阶运动响应影响不大;二阶低频运动相对偏离平衡位置的平均值和标准差均随系泊刚度增大而减小,浮体形状同样对慢漂运动的二阶低频纵荡运动响应影响较大。试验结果为实际海洋工程的外形选择和系泊刚度选择提供数据支持。     

窑洞外形特征对结构抗震性能影响研究

调查发现山西北部农村地区农居窑洞多是独立式土坯窑洞,结构主要受力体系是土坯砌体砌筑拱结构,其建造无统一标准,外形样式存在差异。由于拱结构的内力分布对外形尺寸变化比较敏感,为研究窑洞外形特征对结构抗震性能影响,建立相应的有限元模型进行计算分析,对比不同外形特征窑洞在地震作用下的损伤情况,并结合历史震害,指出窑洞结构的薄弱位置。研究结果表明覆土较厚的窑洞容易损伤,连拱孔数较多窑洞的两侧位置更容易发生破坏,拱的曲线形状对结构抗震性能有一定影响,合理拱曲线窑洞的抗震性能优于一般形状窑洞。