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131.
城市居住小区环境归属感评价——以大连市为例 总被引：12，自引：3，他引：9
研究居民对居住小区环境归属感,进行定量评价并揭示其规律,可为指导城市小区规划设计提供依据。本文以调查问卷的形式,对大连市的居住小区进行调查,充分考虑评价因子的代表性和多层次性的特点,选取5项一级指标和25个单项指标建立评价指标体系;采用层次分析法与地理信息系统软件Surfer 8.0相结合的方法,对大连市居住小区归属感进行初步评价。研究结果表明:影响居住小区归属感的主要因子有舒适感、识别感、安全感、交流感、成就感;大连市居住小区归属感的整体评价较好,市内四区存在差异;归属感的高值区域分布在生态环境风景区、商务活动中心、靠近海岸线的地方及交通便利的地方。 相似文献
132.
133.
Assessment of detachment and sediment transport capacity of runoff by field experiments on a silt loam soil 总被引：2，自引：0，他引：2
The detachment capacity (Dc) and transport capacity (Tc) of overland flow are important variables in the assessment of soil erosion. They determine respectively the lower and upper limit of sediment transport by runoff and therefore control detachment and deposition pro‐cesses. In this study, the detachment and transport capacity of runoff was investigated by rainfall simulations and overland flow experiments on small field plots. On the bare field plots, it was found that Tc was strongly related to total runoff discharge. This was also observed for the plots covered by maize residues, but Tc was less due to the lower runoff velocity. A simple regression equation was derived to estimate Tc for both bare and covered soil. Comparing our observations with Tc equations mentioned in the literature revealed that Tc equations based on laboratory experiments overestimated, on average, our measurements. Although Tc can be assessed more easily in laboratory experiments, the applicability of the results to field conditions remains questionable. Detachment by runoff was also related to total runoff discharge. The Dc values were, however, 4–50 times smaller than the Tc at corresponding high and low runoff discharge. This indicates that detachment by runoff constitutes only part of the transported sediment. Interrill erosion supplies an important additional amount of sediment. In this study, however, only sealed soils were considered. In the case of freshly tilled, loose soils, the Dc of runoff may be larger, resulting in a larger contribution to the total soil loss. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
134.
利用非线性误差增长理论,以Lorenz系统为例比较研究了初始误差和参数误差对混沌系统可预报性的影响．结果表明：在初始误差和参数误差单独存在时,系统的可预报期限随误差大小的变化规律基本上相同;对于相同的误差大小,初始误差和参数误差对系统可预报期限的影响几乎相同,这一结果基本上不随参数范围的变化而变化．当初始误差和参数误差同时存在时,两者对可预报期限影响所起的作用大小主要取决于初始误差和参数误差的相对大小．当初始误差远大于参数误差时,Lorenz系统的可预报期限主要由初始误差决定,可以不用考虑参数误差对预报模式可预报性的影响;反之,当参数误差远大于初始误差时,Lorenz系统的可预报期限主要由参数误差决定;当初始误差和参数误差大小相当时,两者都对系统的可预报期限起重要作用．在后两种情况下,在考虑初始误差对可预报性影响的同时还必须考虑参数误差的作用．这提醒我们在作实际数值天气预报的时候,不仅要重视初值的确定,也要重视数值模式控制参数的确定． 相似文献
135.
Rainfall simulators can be a useful research tool for some purposes but are quite unsuitable for others. They have been useful in soil erosion and infiltration studies for over eight decades, but the possibility of using a rainfall simulator in urban nonpoint source pollution involving urban non-erodible surfaces has not been fully explored. In this review, the versatility of different rainfall simulators of varying sizes, configurations and styles used in the past two decades are appraised for possible adaptation to urban sealed surfaces. Recommended criteria for detailed rainfall simulator reporting are also outlined.
EDITOR M.C. AcremanASSOCIATE EDITOR not assigned 相似文献
136.
Li Li Mark A. Nearing Mary H. Nichols Viktor O. Polyakov Michelle L. Cavanaugh 《地球表面变化过程与地形》2020,45(2):484-495
Terrestrial LiDAR scanning (TLS) technology is widely used to detect terrain elevation changes. This study examines the potential use of terrestrial LiDAR to measure erosion on small experimental plots at high resolution. Multitemporal TLS scans were conducted at six positions around plots (12 m2) with three slope treatments through 11 simulated rainfall applications. Surface elevation changes were quantified by comparing scans between rainfall simulations, and elevation changes greater than the level of detection were used to obtain volumetric change estimations. Erosion mass was estimated both by using soil bulk density and the density of sediment collected in runoff, and then compared to the erosion estimated from the runoff samples. Results showed: (1) with the aid of fixed reference controls in the form of concrete target surfaces of varying roughness, registration accuracy was better than 1 mm and mean level of change detection was less than 2.2 mm; (2) the average absolute relative errors of TLS-estimated eroded mass ranged from 6.8% to 31.8%, with greater values on 5% slope; (3) the TLS-estimated erosion accuracy was affected by erosion magnitude, the utilized material density and number of scan positions, and a grid size of 10 mm was found to be appropriate for this scale to estimate the volumetric changes; (4) the number of scan positions could be reduced to three while not significantly impacting volumetric change estimations; and (5) elevating the scanner resulted in much better accuracy for eroded mass estimations. This study suggests that using LiDAR to monitor soil erosion at the plot scale is feasible, and provides guidance about the level of accuracy one might expect in doing so. © 2019 John Wiley & Sons, Ltd. 相似文献
137.
极化雷达目标分解方法用于岩性分类 总被引：8，自引：0，他引：8
雷达遥感中地表不同岩石类别的后向散射一般判别不大,因此以散射幅度为主要探测因子常规雷达遥感数据不利于岩性分类。极化雷达以散射矩阵或Ｓｔｏｋｅｓ短阵的形式,记录了更多的地物回波信息。信息源的增多,有利于提高岩性分类的精度。但是,由于不同极化状态回波信号之间的关性,极化数据不可避免地产生数据冗余,反而增大了岩性分类的误差。 相似文献
138.
墙体、窗户等单元构件是建筑物重要组成部分,精细提取其几何参数及位置信息对于完整表达建筑物整体模型具有重要意义.针对单一点云数据源无法获取建筑物单元构件相关参数并完整表达室内外模型重建问题,本文提出一整套融合室内外多源点云数据的BIM模型重建技术.为验证方法的有效性,选取河南理工大学测绘与国土信息工程学院教学楼为实验区域... 相似文献
139.
研究Lorenz混沌系统的同步控制问题,提出1种在多输入的情况下实现混沌同步的变结构控制算法.利用该算法设计的变结构同步控制律使得同步误差系统的运动在切换面上成为渐近稳定的滑动模态,从而较快的实现了混沌同步.通过对 Lorenz 混沌系统的理论分析和数值仿真,说明了该变结构同步控制策略的实用性和有效性. 相似文献
140.
渗透率变异系数VK反映样品偏离整体平均值的程度,是评价储层宏观非均质性的最重要参数。介绍了三种渗透率变异系数的计算方法：统计学方法、Dykstra H方法和洛伦兹曲线法,并用三种方法分别计算了宁东油田2、3井区的延8和延9层的渗透率变异系数,比较了三种方法的优缺点和适用范围。实践应用表明,洛伦兹曲线法比较适合本地区的研究,因为它所求出的VK值在0和1之间,具有较强的可比性,能很明确的反应各层位非均质性的程度,而且适合任何分布类型的油藏;统计学方法计算的渗透率变异系数在0~∞之间,用这种方法计算的VK很难建立起该油藏非均质程度的概念;Dykstra H方法适用范围很小,仅适应于渗透率接近于呈对数正态分布的油藏,对本区不太适合。 相似文献