Rainwater harvesting systems: An urban flood risk mitigation measure in arid areas

Rainwater harvesting (RWH) systems have been developed to compensate for shortage in the water supply worldwide. Such systems are not very common in arid areas, particularly in the Gulf Region, due to the scarcity of rainfall and their reduced efficiency in covering water demand and reducing water consumption rates. In spite of this, RWH systems have the potential to reduce urban flood risks, particularly in densely populated areas. This study aimed to assess the potential use of RWH systems as urban flood mitigation measures in arid areas. Their utility in the retention of stormwater runoff and the reduction of water depth and extent were evaluated. The study was conducted in a residential area in Bahrain that experienced waterlogging after heavy rainfall events. The water demand patterns of housing units were analyzed, and the daily water balance for RWH tanks was evaluated. The effect of the implementation of RWH systems on the flood volume was evaluated with a two-dimensional hydrodynamic model. Flood simulations were conducted in several rainfall scenarios with different probabilities of occurrence. The results showed significant reductions in the flood depth and flood extent, but these effects were highly dependent on the rainfall intensity of the event. RWH systems are effective flood mitigation measures, particularly in urban arid regions short of proper stormwater control infrastructure, and they enhance the resilience of the built environment to urban floods.

Localization and mapping in urban area based on 3D point cloud of autonomous vehicles

In order to meet the application requirements of autonomous vehicles, this paper proposes a simultaneous localization and mapping （SLAM） algorithm, which uses a VoxelGrid filter to down sample the point cloud data, with the combination of iterative closest points （ICP） algorithm and Gaussian model for particles updating, the matching between the local map and the global map to quantify particles＇ importance weight. The crude estimation by using ICP algorithm can find the high probability area of autonomous vehicles＇ poses, which would decrease particle numbers, increase algorithm speed and restrain particles＇ impoverishment. The calculation of particles＇ importance weight based on matching of attribute between grid maps is simple and practicable. Experiments carried out with the autonomous vehicle platform validate the effectiveness of our approaches.

用MAPS模式预报冰雹落区

文中详细分析了 1982～ 1998年发生在湖北省的冰雹过程 ,这些冰雹过程被归纳为槽前型和槽后型两类。两类过程的一个共同特点是过程发生前具有极强的位势不稳定。槽前型主要表现在中低空及地面为极强的增湿增暖 ,导致中低空能级升高 ,而中高层是相对干冷的区域或变化不是很大 ,这类过程的触发主要是由于西北槽中有短波槽扰动凌驾于不稳定区之上 ,一方面加大水平能量锋区 ,另一方面使得垂直不稳定度加大 ,进而触发对流。槽后型主要表现在中高层为极强的干冷平流 ,引起降温降湿 ,而低层有弱的增温增湿 ,这类过程的触发主要是西北气流中横槽转动和小槽沿脊前下滑 ,在中低层加大水平能量锋区 ,促进垂直不稳定能量的释放。因此将水平能量锋区ΔθseH/Δn和垂直不稳定ΔθseH/Δz之和作为冰雹判据 ,辅之以其它条件 ,在日常业务中 ,具有较高的预报准确率。利用研究结果 ,对武汉区域中心数值预报模式MAPS的积云对流参数化方案进行改进 ,即改进积云对流参数化中的稳定度条件。用改进后的MAPS模式对 1999～ 2 0 0 1年 3～ 5月的过程进行试报 ,结果表明 ,该模式对冰雹落区有一定的预报能力。

Methods to extract impervious surface areas from satellite images

Impervious surface area(ISA)is an important parameter for many environmental or socioeconomic relevant studies.The unique characteristics of remote sensing data made it the primary data source for ISA mapping at various scales.This paper summarizes general ISA mapping procedure and major techniques and discusses impacts of scale issues on selection of remote sensing data and corresponding algorithms.Previous studies have indicated that ISA mapping remains a challenge,especially in urban–rural frontiers and in covering a large area.Effectively employing rich spatial information in high spatial resolution imagery through texture and objectbased methods is valuable.Data fusion of multi-resolution images and spectral mixture analysis are common approaches to reduce the mixed pixel problem in medium spatial resolution images such as Landsat.Coarse spatial resolution images such as MODIS and DMSP-OLS are valuable for national and global ISA mapping but more research is needed to effectively integrate multisource/scale data for improving mapping performance.Development of an optimal procedure corresponding to specific study areas and purposes is required to generate accurate ISA mapping results.

Comparisons of two global built area land cover datasets in methods to disaggregate human population in eleven countries from the global South

Mapping built land cover at unprecedented detail has been facilitated by increasing availability of global high-resolution imagery and image processing methods.These advances in urban feature extraction and built-area detection can refine the mapping of human population densities,especially in lower income countries where rapid urbanization and changing population is accompanied by frequently out-of-date or inaccurate census data.However,in these contexts it is unclear how best to use built-area data to disaggregate areal,count-based census data.Here we tested two methods using remotely sensed,built-area land cover data to disaggregate population data.These included simple,areal weighting and more complex statistical models with other ancillary information.Outcomes were assessed across eleven countries,representing different world regions varying in population densities,types of built infrastructure,and environmental characteristics.We found that for seven of 11 countries a Random Forest-based,machine learning approach outperforms simple,binary dasymetric disaggregation into remotely-sensed built areas.For these more complex models there was little evidence to support using any single built land cover input over the rest,and in most cases using more than one built-area data product resulted in higher predictive capacity.We discuss these results and implications for future population modeling approaches.

基于组织模型的纬编面料透气性数字化预测

为在投入实际生产前正确评估双面纬编面料的透气性能,构建了双面织物组织模型,并进行织物孔隙率的数字化表达。首先,对双面纬编织物结构中包含的成圈、集圈和浮线这3种基本线圈形态进行孔隙率的单元组织模型构建;然后系统归纳出双层结构中9种正面结构单元和21种反面结构单元,并构建双层结构孔隙率矩阵,得到织物理论孔隙率的计算方法;最后,在3款不同组织的面料基础上通过线性拟合得出理论孔隙率与透气率的关系,并选用2款面料验证预测系统的准确性。结果表明:理论计算的透气率为627.0、688.6 mm/s,实际测量的透气率为600.3、676.3 mm/s,其误差率在±6%以内,说明构建的纬编组织模型和透气性预测方法具有合理性和适用性。

Spatial Transferability of Vegetation Types in Distribution Models Based on Sample Surveys from an Alpine Region

Vegetation mapping using field surveys is expensive. Distribution modelling, based on sample surveys, might overcome this challenge. We tested if models trained from sample surveys could be used to predict the distribution of vegetation types in neighbourhood areas, and how reliable the spatial transferability was. We also tested whether we should use ecological dissimilarity or spatial distance to foresee modelling performance. Maximum entropy models were run for three vegetation types based on a vegetation map within a mountain range. Environmental variables were selected backwards, model complexity was kept low. The models are based on points from a small part of each study site, transferred into the entire sites, and then tested for performance. Environmental distance was tested using principle component analysis. All models had high uncorrected AUC values. The ability to predict presences correctly was low. The ability to predict absences correctly was high. The ability to transfer the distribution model depended on environmental distance, not spatial distance.

基于ISM模型的设施布置优化方法

随着社会的发展,设施规划由于能减少运营成本越来越受到重视。考虑到现有设施布置方法相对复杂,在运用系统化设施布置原理和方法的基础上,引入解析结构模型和计算机编程方面的知识,得出一种设施布置的优化方法。该方法能够高效地得到相对合理的设施布置方案。首先运用ISM模型将各个工作单元之间的相互关系梳理清楚,之后通过工作单元之间综合关系密切程度以及面积图法对得到的ISM模型进行调整,最终得出科学合理的设施布置。

基于HPLC的低压台区三相不平衡优化调整方法

针对低压台区三相不平衡的问题,提出了一种基于HPLC的低压台区三相不平衡优化调整方法。该方法首先基于HPLC模块构建台区相位拓扑图;根据获取的变压器侧、各主干线、各支路、各计量点的用电负荷数据,计算各节点及用户终端三相不平衡度;最后采用模型预测控制方法,获取兼顾三相不平衡度和换相操作次数最小化的换相调整策略。试点应用表明,所提方法能在保证换相操作次数较少的情况下,实现三相负荷相对平衡,使试点台区线损率由3.56%下降至2.75%。

基于ArcGIS模型构建器的多灌区一张图矢量数据批量合并方法研究

灌区一张图建设是实现灌区现代化、信息化、数字化的首要工作。当前,全国开展以灌区为单元的灌区一张图建设工作,收集了大量灌区一张图矢量数据。文章研究了基于GIS模型构建器的多灌区一张图矢量数据批量合并方法,通过GIS模型构建器中的迭代工作空间结合追加工具,介绍了快速实现多灌区一张图矢量数据合并到指定地理信息数据库的模型建立步骤和使用方法。该模型的应用可快速高效地实现多个灌区一张图矢量数据合并,使用简捷。

基于多源大数据和人口分布视角的青岛市中心城区空间结构研究

以青岛市中心城区为例,基于动态的百度热力图和静态的POI数据,借助ArcGIS技术平台,采用栅格计算、核密度分析、耦合协调模型等方法,探究时空两个维度下人群集聚度、集聚位置、活动重心、与POI分布的耦合关系以及城市公共中心等特征。结果表明:工作日人群活动在时空上均受制于通勤节奏,高热力持续时间久;休息日在出行时间上存在滞后特征,空间位置主要集中在商业综合体;人口活动重心迁移在休息日时呈逆时针环形轨迹特征,工作日时轨迹范围更广,反映出就业和商业重心位于居住重心的东北方向;青岛市中心城区人口聚集与POI密度耦合协调关系良好,空间分布上具有“大集聚、小分散”的城市中心体系,存在各级中心发展不平衡、一强多弱等现象。

基于固定翼航测无人机的城市建成区地形图快速更新

城市建成区是城市建设发展在地域分布上的客观反映,是智慧城市建设的主要区域。针对城市建成区地物信息丰富、区域面积较大等特点,提出利用国产固定翼航测无人机获取城市建成区高分辨率影像数据,完成建成区1∶500大比例尺地形图快速更新的技术方法,并对成果精度和作业效率进行检测对比。结果表明,该方法在城市建成区地理信息快速更新中具有较好适用性。

面向目标结构信息保持的SAR真正射遥感影像生成方法

SAR遥感影像中的几何结构信息对于目标识别和判读具有十分重要的意义。现有SAR遥感影像的正射校正方法沿用光学正射影像(DOM)的校正思路,直接利用物方-像方采样进行,SAR遥感影像叠掩现象所引起的几何畸变会对目标结构信息提取造成干扰。针对以上问题,该文提出一种面向目标结构信息保持的SAR真正射影像(TDOM)制作方法,基于高精度数字表面模型(DSM),通过像方-物方反投影提取像方影像中的叠掩区域;然后,针对叠掩区域进行多高程面投影拟合分析,将雷达波与物方高程最高处的交点作为真实物方投影点,生成单视向SAR真正射影像;最后,利用不同视向的SAR真正射影像进行缺失信息补偿,得到融合后的多视向SAR真正射影像。以高分三号SAR影像作为研究对象,实验结果表明,相比于传统SAR正射影像,该文所提方法能够更好地保持目标结构信息,有效提升处理后SAR影像的目标识别和判读能力。

黔西北猪拱塘铅锌矿区数字勘查应用

勘查大数据是种科学大数据(张夏林等,2021)。它们是在矿产勘查过程中的不同时间、不同阶段,按照定规范所获取的,具有多源、多类、多维、多时空等特点(赵林林等,2019)。资源勘查野外数据采集具有数据量大、种类多样的特点,是地质大数据的主要来源之(李丰丹等,2019)。野外数据是实际情况真实信息记录的载体,具有原始性、基础性、可靠性,但很多工作前期由于环境艰苦,手段传统,基本上是呈纸质版零散分布.

基于GNSS技术的农村土地面积测量精度估算方法

为进一步提升土地面积测量的精度,本次开展基于全球导航卫星系统(GNSS)技术的农村土地面积测量精度估算方法的研究。首先基于GNSS技术构建几何定位模型,对定位点中各参数进行深层解析;然后将得到的定位数据与测绘数据通过坐标系转换、栅格滑动赋值等步骤实现数据的归一化;最后将数据代入模型之中,完成测绘精度估算方法的设计。实验结果表明:在不同比例尺下,设计的估算方法预测的控制点与实际情况较相符,可进行准确的土地面积测量精度估算,具有一定可靠性。

基于ArcGIS模型构建器的国土调查数据质量检查

为了快速找出问题数据,提升国土调查数据精度,保证国土调查成果具有现实意义,提出基于ArcGIS模型构建器的国土调查数据质量检查方法。依据国土调查数据质检要求,在ArcGIS平台框架下,利用ArcGIS模型构建器建立国土调查数据质量检查模型,将本次国土调查地类图斑数据及历年耕地图层数据作为模型的输入变量,将国土调查的问题图斑作为模型的输出变量,整个模型的运行过程包括本次国土调查地类图斑数据的筛选、不同地类的提取以及净面积运算、历年耕地图层的融合以及数据相交等环节,ArcGIS模型构建器将这些环节组建成一个工作流,使多步骤的国土调查数据质检操作,可以在ArcGIS平台下达的同一指令下完成。实验证明:利用该方法能够准确检查出国土调查数据中出现的问题,所提数据相交方法,可以使整个国土图斑得到较好的整合,方便后续工作的开展。

基于建筑功能视角的住宅商品房基本房产分摊模型探究

对住宅商品房的房产测绘分摊问题进行了分析,从住宅商品房的建筑功能组成、共用区和基本单元的划分、确定共用区分摊范围等方面进行了论述,进行了住宅商品房的分摊级别、分摊计算方法等研究,提出了基于建筑功能来建立住宅商品房基本分摊模型的方法,解决了难以界定共用区分摊范围的问题,使得房产测绘成果更加科学合理、行业更加公开透明。

北京山区植被覆被率遥感制图与景观格局分析——以门头沟区为例

准确、快速地获取植被覆盖状况信息是北京山区生态恢复和建设的关键与重点。本文在FCDMappingmodel的原理和方法基础上,利用TM图像对北京门头沟区植被覆被率展开调查和制图应用研究,并利用FRAGSTATS软件对所得的植被覆盖等级图从斑块大小、斑块数、斑块密度、斑块平均面积、分形维数和聚集度等角度进行了空间格局的剖析。

塔中围斜区连片精细速度建模与变速成图

塔中围斜区断裂构造复杂,构造形态难以落实。由于数据采集年代、施工参数、处理方法、野外地震和地质条件等方面的差异,连片整体速度研究及构造成图是研究该地区构造形态的关键。针对整体构造评价薄弱的问题及勘探部署难以决策的迫切需求,研究了塔中围斜区八个区块连片精细速度建模及变速成图技术。通过速度基准面统一技术、速度闭合差分析校正技术和基于解释层位框架控制的速度去噪技术的研究,获得了塔中八连片整体速度模型及各地震反射层整体构造图。