基于微波辐射计的短时强降水潜势预报

微波辐射计可获取高时间分辨率的大气层结信息,为探索其在短时强降水预报方面的应用潜力,利用微波辐射计仪器获得对流参数特征,提取对短时强降水敏感的对流参数作为预报因子,并利用叠套法建立短时强降水潜势预报.结果表明:液态水路径LWP、SI、LI、CAPE、KOI这5种参数可作为预报因子建立潜势预报,经验证后得出短时强降水的P...     

地电阻率供电回路故障检测板的研制与使用

地电阻率仪器在工作中容易出现无电流、电流不稳等故障现象,不易排查维修.通过对仪器工作原理和供电回路过程进行研究,发现供电回路中间仪器的内部或外部各接头接触不良是造成上述现象的主要因素.根据存在的问题,洛阳地震台研制出供电回路故障检测板.该检测板可利用其继电器上LED灯的工作状态和动作时序,快速查找、排除相关供电回路故障...     

2015-2019年贵港市臭氧污染特征及其与气象要素的关系

为研究贵港市O3(臭氧)污染特征及其与气象要素的关系,对2015-2019年贵港市国家空气自动监测站和同期贵港国家气象观测站逐日、逐时气象资料进行了研究和分析.结果表明:近5a来贵港市O3污染日趋严重;O3污染存在明显的季节变化,秋＞夏＞春＞冬;O3浓度日变化特征呈单峰型,8:00出现谷值,15:00-16:00出现峰...     

中国土地行政复议案件时空格局演变及宏观驱动机制

基于2000~2015年中国省（市、区）土地行政复议案件数量、案由与复议结果等数据,定量探究中国土地行政复议案件的分布特征、格局演变与宏观驱动机制。研究表明：中国年度土地行政复议案件数量整体呈连续增加态势,行政相对人复议成功率先下降后上升。土地行政复议案件的空间分布与中国宏观人口-经济格局基本匹配,整体具有东南多西北少的分异特征,以中部主要省份为核心,经历了先向东部沿海、后向西北与西南地区蔓延的演进过程。中国土地行政复议案件的时空格局演变由经济发展水平、城市化水平、产业结构升级、城市建成区面积、土地财政收入状况、土地市场化水平、区位条件等因素共同驱动。     

腾格里沙漠东南缘人工固沙植被区表层土壤有机碳矿化对凋落物添加的响应

土壤有机碳矿化是调控土壤碳库时空格局、土壤碳收支平衡和植物养分供应的重要过程,植物残体和凋落物分解释放CO₂直接影响着土壤有机碳矿化。研究了不同类型凋落物对腾格里沙漠东南缘建植于1956年的人工固沙植被区土壤有机碳矿化过程及其对水分和温度的响应特征。结果表明：凋落物添加显著促进了有机碳矿化,添加柠条锦鸡儿（Caragana korshinskii）、油蒿（Artemisia ordosica）、小画眉草（Eragrostis minor）凋落物后,CO₂-C最大矿化速率分别增大了6.94、5.17、3.46倍,0~5 cm层土壤是5~10 cm层土壤的1.09、1.55、1.22倍;CO₂-C累积释放量分别增加了3.73、3.38、2.34倍,0~5 cm层土壤是5~10 cm层土壤的1.17、1.30、1.57倍。凋落物对有机碳矿化的促进作用与温度和水分密切相关,25℃时,CO₂-C平均释放速率、最大释放速率、累积碳释放量分别是10℃的2.21、3.60、2.21倍,而含水量10%时,CO₂-C平均释放速率、最大释放速率和累积碳释放量分别是含水量5%时的1.25、1.20、1.25倍。相关性分析表明,凋落物碳氮含量、碳氮比、木质素比氮和土壤有机碳以及全氮是影响有机碳矿化的主要因子。凋落添加土壤后潜在可矿化碳表现为柠条锦鸡儿>油蒿>小画眉草>对照。凋落物添加显著促进了有机碳矿化过程及碳周转,植被恢复过程中草本植物凋落物的输入更有利于土壤碳固存,凋落物对土壤碳库的调控作用受土壤理化性质和水热等环境因子的共同作用影响。     

Identification of dissolved and particulate carbonyl compounds produced by marine harmful algal bloom species

Carbonyl compounds, especially polyunsaturated aldehydes (PUAs), are increasingly reported as teratogenic to grazers and deleterious to phytoplankton. While PUAs have been considered to be mainly produced by diatoms after cell wounding, little is known about whether microalgae other than diatoms, particularly harmful algal bloom (HAB)-forming species, produce carbonyl compounds. In this study, we analyzed the carbonyl compounds from eight common HAB-forming species ( Akashiwo sanguinea , Karenia mikimotoi , Karlodinium venefi cum , Margalefi dinium polykrikoides , Prorocentrum donghaiense , P . minimum , Scrippsiella trochoidea , and Heterosigma akashiwo ) using gas chromatography-mass spectrometry in full scan and selected ion monitoring (SIM) modes. Our results show a ubiquitous presence of carbonyl compounds in both dissolved and particulate forms in all species we examined. In the full scan mode, 133 chromatographic peaks were detected from 51 samples altogether. Both the varieties of carbonyl compounds and their quantities were algal species dependent, although most of the carbonyl compounds could not be fully identifi ed according to the mass spectral database only due to the unavailability of enough standards for all analytes. Aided with nine standards in SIM mode, we further identifi ed and quantifi ed all nine aldehydes (2-methyl-2-pentenal, trans-2-nonenal, cis-6-nonenal, 2,6-dimethyl-5-heptenal, trans-2-hexenal, trans-2- decenal, 2,4-heptadienal, trans-trans-2,4-octadienal, and trans-trans-2,4-decadienal). Four of these nine aldehydes were detected in particulate form, which confi rmed that trans-2-nonenal could be produced by K . mikimotoi , Karl . venefi cum , P . donghaiense , P . minimum , S . trochoidea , and H . akashiwo , 2,4-heptadienal and trans-trans-2,4-decadienal by A . sanguinea , M . polykrikoides , and S . trochoidea , and trans, trans-2,4- octadienal by S . trochoidea , respectively. We proved that some dinofl agellate and raphidophyte species could contribute to the pool of carbonyl compounds including PUAs in a marine ecosystem. Some carbonyl compounds, particularly those in high cell quota and/or dissolved concentration, may be related to fi shkilling or allelopathy which needs further identifi cation and quantifi cation.     

遥感影像并行处理的数据划分及其路径优化算法

研究了一种基于数据划分的遥感影像并行处理的路径优化算法,用于解决将并行技术应用于海量遥感影像分布式存储和处理领域时其处理模型所具有的多路可达性所引起的路径动态、最优选择问题。在栅格数据可分解性分析及并行模型数据态、元素、相对信息量和映射等8个基本定义和6个性质的基础上,给出并行处理一般数学模型。以该模型为基础获得在一般并行处理情况下,以平均计算代价变量的比值作为控制横向并行与纵向并行选择方式的标志,并进一步给出四叉树索引并行生成、基于四叉树的目标检测并行处理等具体示例。最后,通过试验验证了算法的有效性,分析了算法的特点及影响因素。     

低空摄影测量立体影像匹配的现状与展望

影像匹配是在两幅或多幅具有重叠度的影像中通过特定的算法提取影像间同名点的过程,是低空摄影测量数据处理中最为关键的步骤,匹配质量与效率直接影响到后续数据处理的成功与否,关系到测绘产品生成质量。本文系统阐述了低空摄影测量影像匹配的研究现状与展望。对影像匹配的分类进行总结和归纳,大体上,影像匹配可划分为两大类,即基于灰度和基于特征的匹配。重点针对基于特征的影像匹配,从点、线、面等特征提取算法及特征描述符和相似性测度与策略等方面进行了详细阐述。此外,列举最新的基于深度学习的影像匹配算法,对低空平台搭载的多样化传感器数据融合可能涉及的影像匹配方法进行了展望。     

Detecting arbitrarily shaped clusters in origin-destination flows using ant colony optimization

An origin-destination (OD) flow can be defined as the movement of objects between two locations. These movements must be determined for a range of purposes, and strong interactions can be visually represented via clustering of OD flows. Identification of such clusters may be useful in urban planning, traffic planning and logistics management research. However, few methods can identify arbitrarily shaped flow clusters. Here, we present a spatial scan statistical approach based on ant colony optimization (ACO) for detecting arbitrarily shaped clusters of OD flows (AntScan_flow). In this study, an OD flow cluster is defined as a regional pair with significant log likelihood ratio (LLR), and the ACO is employed to detect the clusters with maximum LLRs in the search space. Simulation experiments based on AntScan_flow and SaTScan_flow show that AntScan_flow yields better performance based on accuracy but requires a large computational demand. Finally, a case study of the morning commuting flows of Beijing residents was conducted. The AntScan_flow results show that the regions associated with moderate- and long-distance commuting OD flow clusters are highly consistent with subway lines and highways in the city. Additionally, the regions of short-distance commuting OD flow clusters are more likely to exhibit ‘residential-area to work-area’ patterns.     

Integration of nighttime light remote sensing images and taxi GPS tracking data for population surface enhancement

The population distribution grid at fine scales better reflects the distribution of residents and plays an important role in investigating urban systems. The recent years have witnessed a growing trend of applying the nighttime light data to the estimation of population at micro levels. However, using the nighttime light data alone to estimate population may cause the overestimation problem due to excessively high light radiance in specific types of areas such as commercial zones and transportation hubs. In dealing with this issue, this study used taxi trajectory data that delineate people’s movements, and explored the utility of integrating the nighttime light and taxi trajectory data in the estimation of population in Shanghai at the spatial resolution of 500 m. First, the initial population distribution grid was generated based on the NPP-VIIRS nighttime light data. Then, a calibration grid was created with taxi trajectory data, whereby the initial population grid was optimized. The accuracy of the resultant population grid was assessed by comparing it with the refined survey data. The result indicates that the final population distribution grid performed better than the initial population grid, which reflects the effectiveness of the proposed calibration process.