Curve matching approaches to waveform classification: a case study using ICESat data

Light Detection and Ranging (LiDAR) waveforms are being increasingly used in many forest and urban applications, especially for ground feature classification. However, most studies relied on either discretizing waveforms to multiple returns or extracting shape metrics from waveforms. The direct use of the full waveform, which contains the most comprehensive and accurate information has been scarcely explored. We proposed to utilize the complete waveform to test its ability to differentiate between objects having distinct vertical structures using curve matching approaches. Two groups of curve matching approaches were developed by extending methods originally designed for pixel-based hyperspectral image classification and object-based high spatial image classification. The first group is based on measuring the curve similarity between an unknown waveform and a reference waveform, including curve root sum squared differential area (CRSSDA), curve angle mapper (CAM), and Kullback–Leibler (KL) divergence. The second group assesses the curve similarity between an unknown and reference cumulative distribution functions (CDFs) of their waveforms, including cumulative curve root sum squared differential area (CCRSSDA), cumulative curve angle mapper (CCAM), and Kolmogorov–Smirnov (KS) distance. When employed to classify open space, trees, and buildings using ICESat waveform data, KL provided the highest average classification accuracy (87%), closely followed by CCRSSDA and CCAM, and they all significantly outperformed KS, CRSSDA, and CAM based on 15 randomized sample sets.     

A comparative study of landslide susceptibility mapping using weight of evidence,logistic regression and support vector machine and evaluated by SBAS-InSAR monitoring: Zhouqu to Wudu segment in Bailong River Basin,China

The determining of landslide-prone areas in mountainous terrain is essential for land planning and hazard mitigation. In this paper, a comparative study using three statistical models including weight of evidence model (WoE), logistic regression model (LR) and support vector machine method (SVM) was undertaken in the Zhouqu to Wudu segment in the Bailong River Basin, Southern Gansu, China. Six conditionally independent environmental factors, elevation, slope, aspect, distance from fault, lithology and settlement density, were selected as the explanatory variables that may contribute to landslide occurrence based on principal component analysis (PCA) and Chi-square test. The relation between landslide distributions and these variables was analyzed using the three models and the results then used to calculate the landslide susceptibility (LS). The performance of the models was then evaluated using both the highly accurate deformation signals produced by using the Small Baseline Subset Interferometric Synthetic Aperture Radar technique and Receiver Operating Characteristic (ROC) curve. Results show more deformation points in areas with high and very high LS levels, and also more stable points in areas with low and very low LS levels for the SVM model. In addition, the SVM has larger area under the ROC curve. It indicates that the SVM has better prediction accuracy and classified ability. For the interpretability, the WoE derives the class of factors that most contributed to landsliding in the study area, and the LR reveals that factors including elevation, settlement density and distance from fault played major roles in landslide occurrence and distribution, whereas the SVM cannot provide relative weights for the variables. The outperformed SVM could be employed to determine potential landslide zones in the study area. Outcome of this research would provide preliminary basis for general land planning such as choosing new urban areas and infrastructure construction in the future, as well as for landslide hazard mitigation in Bailong River Basin.     

Climate impacts: temperature and electricity consumption

Natural Hazards - One of the aspects of climate change is temperature rise. Temperature rise or fluctuations affect human economic activities and electricity consumption. This paper estimates the...     

Experimental research on macroscopic and mesoscopic evolution mechanism of land subsidence induced by groundwater exploitation

Natural Hazards - Land subsidence induced by groundwater exploitation is a typically multi-scale and multi-field coupling process. The adjustment process and action mechanism of soil mesostructure...     

球状星团致密度及其演化

根据球状星团动力学演化理论,本文探讨了球状星团致密度的演化与球状星用质量和位置的关系。结果表明,银心距和球状星团质量都与致密度的演化紧密相关。一般来说,银心距很大时致密度演化极少,球状星团质量愈大致密度演化愈缓慢。对现有球状星团致密度的分布作了统计研究,结果表明,在银心距较小的区域,致密度的分布与理论分析结果一致。在大银心距处发现,质量不同的球状星团其致密度分布有明显不同,它可能反映了球状星团形成阶段其致密度与质量紧密相关。     

华南上泥盆统法门阶哲杜斯贝动物群的埋藏学和居群动力学特征*

哲杜斯贝是一种以高丰度和低物种分异度为显著特征、在全球广泛独立分布的小嘴贝类。笔者对华南台地相和台间盆地相5个含哲杜斯贝类上泥盆统剖面进行沉积环境和埋藏特征研究,确定华南哲杜斯贝类的原生沉积环境为台地的正常浅水,这与美国和摩洛哥生长在冷泉环境中的哲杜斯贝不同,表明其既可在浅海环境中生长,也可以在冷泉环境中生长,具有较强的生态可塑性。台地相(原地埋藏)的3个哲杜斯贝种群具有以下特征:(1)均呈现出壳体呈层状紧密堆积、集群生长特点,丰度极高,并且有相当数量的个体呈现出由于拥挤生长而导致的壳体生长畸形现象;(2)缺乏其他底栖后生生物,显示了极低的生物多样性;(3)壳体大小—频率分布和生存曲线揭示了3个哲杜斯贝种群都具有非常低的幼年期死亡率特点,同时同一介壳层内哲杜斯贝个体大小均一,表明绝大多数的个体能够达到或接近自然寿命后死亡。上述证据表明,哲杜斯贝具有密集群居生活的习性,其生活在一个独特的、不适合其他后生底栖生物生存的环境。     

GM3磁通门磁力仪稳定性分析

通过2002～2003年的GM3磁通门磁力仪的资料,对该仪器的各项指标进行稳定性分析,考核运行状态是否正常,以证明是否替代模拟观测仪器。     

The status of the ecological environment and a proposed protection strategy in Sanya Bay,Hainan Island,China

Sanya Bay encompasses a high diversity of natural habitats, ranging from coral reefs, rocky and sandy shores and mudflats to mangroves. Seasonal physicochemical and biological investigations were conducted from 1998 to 1999 and again in April 2000. Water-related environmental quality in Sanya Bay is in good condition. The levels of dissolved oxygen, nitrogen, phosphorus and heavy metals are within the first class of National Seawater Quality Standards for China. Annual mean values of chlorophyll a of 0.93 mg m(-3) and phytoplankton primary productivity of 440.8 mgC m(-2)d(-1), respectively, were found in the waters, both of which show a significant correlation with inorganic nitrogen. A mean new productivity of 144.6 mgC m(-2) d(-1) was recorded in summer. Sanya Bay is rich in natural resources and biodiversity with 235 species of phytoplankton and 129 species of zooplankton identified in the survey. The annual mean abundance of phytoplankton and zooplankton were 1564 x 10 cells m(-3) and 121 individuals m(-3), respectively, with an annual mean zooplankton biomass of 129 mg m(-3). A total of 243 species of fish were sampled in the survey including many of high economic value. Three hundred and eighty-four species of benthos in 121 families were found by mud sampling and trawling. The average biomass of benthic organisms was 11.55 gm(-2), with a density of 31 individuals m(-2). Molluscs were the dominant group, followed by crustaceans; coelenterates exhibited the lowest biomass. One hundred and twenty-six species from 48 families of intertidal organisms were collected by frame sampling, with a mean annual biomass of 644.7 gm(-2) and average density of 816 individuals m(-2). The highest biomass of 1673.5 gm(-2) was collected in a coral reef region, while the highest density of 1219 individuals m(-2) occurred in a mangrove region. The coastline is characterized by coral reefs that accounts for 30% of the total coastline length in the bay, so coral reefs are a key ecosystem that are important for maintaining the regional marine resources and biodiversity. We need to pay much more attention to such diverse marine resources to maintain the integrity and function of these coastal ecosystems.     

震情过程追踪与发震时间的综合概率预报

基于大震前主破裂潜在变化的过程中产生出小震活动、地壳形变异常以及伴随地壳形变而产生出的地下水、水化学、地电阻率等前兆现象随时间变化显示出的动态异常图象,依据河北省及周围地区１９７０年至１９８８年的中强震前的前兆异常资料的研究,提取出了９个前兆异常因子的异常变化规律及特征,并建立了务因子的概率预报模型,同时计算出相应的前兆发生后不同时段内地震发生的概率。最后在多个因子随时间推移而逐次出现前兆异常的情     

浙江干旱特征及其与区域气候变化关系

应用干旱综合指数对浙江自1952年以来的干旱年代际变化特征进行研究,用小波分析方法对50多年来的夏秋季降水、气温进行分析.研究指出:浙江发生强干旱往往会连续两年出现;在20世纪50、60年代及21世纪以来浙江干旱强度比较强,强干旱的发生与夏季气温偏高、降水偏少是同步的;70年代末气候发生突变,浙江从干旱期转入湿润期,21世纪以来,气候有一次小振动,浙江由湿润期转入干旱多发.