不透水面提取技术在第三次全国国土调查标准时点更新工作中的应用研究     

刘韶军  吕春阳 《测绘与空间地理信息》2021,44(7):123-125,130

以榆中县为样本,研究利用Landsat-8卫星遥感数据,提取和分析不透水面变化信息,用于辅助第三次全国国土调查统一时点更新工作.研究结果表明,使用归一化差值不透水面算法提取的不透水面变化信息准确度高、适用范围大,可以为统一时点更新工作提供指引,减轻人工目视判读寻找变化区的工作量并避免遗漏.  相似文献   

Effects of temperature and salinity on the development of embryos and larvae of the veined rapa whelk Rapana venosa （Valenciennes, 1846）   总被引：1，自引：0，他引：1  

班绍君  张涛  潘恒倩  潘洋  王平川  薛东秀 《中国海洋湖沼学报》2014,32(4):773-782

The major population of the veined rapa whelk Rapana venosa(Valenciennes, 1846), which is an important fishery resource, is facing a large decline in China. We studied the effects of incubation temperature(16–34℃ at salinity 30) and salinity(5–45 at 25℃) on the incubation period and subsequent larval development. In the temperature experiment, the shortest incubation period was 12 days at 34℃, the lower temperature limit was 16℃, the longest mean shell length(1 193±17 μm) occurred at 25℃ and the highest survival rate 72.28%±5.62% was observed at 28℃. In the salinity experiment, the shortest incubation period was 15 days at 25. The salinity tolerance range was 15–40, the longest mean shell length(855±9 μm) and the highest survival rate 72.93%±4.85% were both observed at 35. This study demonstrated that, during the egg–mass stage, temperature and salinity regimes infl uence later growth and survival of larvae. These observations deepen our understanding of the ecology and conservation of natural populations of Rapana venosa.  相似文献   

A scheme for weak GPS signal acquisition aided by SINS information     

Xinlong Wang  Xinchun Ji  Shaojun Feng 《GPS Solutions》2014,18(2):243-252

In order to enhance the acquisition performance of global positioning system (GPS) receivers in weak signal conditions, a high-sensitivity acquisition scheme aided by strapdown inertial navigation system (SINS) information is proposed. The carrier Doppler shift and Doppler rate are pre-estimated with SINS aiding and GPS ephemeris, so that the frequency search space is reduced, and the dynamic effect on the acquisition sensitivity is mitigated effectively. Meanwhile, to eliminate the signal-to-noise ratio gain attenuation caused by data bit transitions, an optimal estimation of the unknown data bits is implemented with the Viterbi algorithm. A differential correction method is then utilized to improve the acquisition accuracy of Doppler shift and therefore to meet the requirement of carrier-tracking loop initialization. Finally, the reacquisition experiments of weak GPS signals are implemented in short signal blockage situations. The simulation results show that the proposed scheme can significantly improve the acquisition accuracy and sensitivity and shorten the reacquisition time.  相似文献   

塔南凹陷岩性油藏成藏条件与4种成藏模式   总被引：1，自引：0，他引：1       下载免费PDF全文

刘绍军  李强  李红英  张湘娟  王立东 《地质科学》2011,46(4):1106-1118

本文分析了塔南凹陷岩性油藏的成藏条件,结果表明,开阔的复式箕状断陷结构使塔南凹陷形成了多凸多凹、凹隆相间的构造格局,为岩性油藏的形成创造了有利的空间;南屯组多沉积中心发育的优质烃源岩为岩性油藏发育提供了物质基础;同沉积断裂及其配置关系决定了塔南凹陷具有沟谷控源、转换带控扇、断坡控砂的成盆特点,水下扇中扇,三角洲前缘和远...  相似文献   

基于卫星遥感的南海真光层底颗粒有机碳输出通量时空特征研究          下载免费PDF全文

刘少军  蔡大鑫  韩静  罗琪  赵婷  张廷龙 《山东气象》2022,42(1):32-38

在加强海洋强国建设、实现我国碳达峰和碳中和愿景目标背景下准确掌握南海碳通量时空变化格局具有重要的现实意义。根据2009—2018年10 a有机碳通量月度数据集,分析了南海真光层底颗粒有机碳通量变化特征。结果表明:(1)南海区域多年真光层底有机碳输出通量年平均值为55.40 mgC·m^-2·d^-1;其值大小在空间上的分布存在近岸＞陆架＞海盆的趋势。(2)从季节上看,南海真光层底颗粒有机碳输出通量冬季最高,春、秋季次之,夏季最小;真光层底颗粒有机碳输出通量1、4、7、10月平均值分别为82.43、47.37、46.34、54.75 mgC·m^-2·d^-1。研究结果可为全面掌握南海碳循环过程和机制提供技术支撑。  相似文献   

Probabilistic analysis of tunnel displacements based on correlative recognition of rock mass parameters     

Minzong Zheng  Shaojun Li  Hongbo Zhao  Xiang Huang  Shili Qiu 《地学前缘(英文版)》2021,12(4):101136

Displacement is vital in the evaluations of tunnel excavation processes,as well as in determining the postexcavation stability of surrounding rock masses.The prediction of tunnel displacement is a complex problem because of the uncertainties of rock mass properties.Meanwhile,the variation and the correlation relationship of geotechnical material properties have been gradually recognized by researchers in recent years.In this paper,a novel probabilistic method is proposed to estimate the uncertainties of rock mass properties and tunnel displacement,which integrated multivariate distribution function and a relevance vector machine(RVM).The multivariate distribution function is used to establish the probability model of related random variables.RVM is coupled with the numerical simulation methods to construct the nonlinear relationship between tunnel displacements and rock mass parameters,which avoided a large number of numerical simulations.Also,the residual rock mass parameters are taken into account to reflect the brittleness of deeply buried rock mass.Then,based on the proposed method,the uncertainty of displacement in a deep tunnel of CJPL-II laboratory are analyzed and compared with the in-situ measurements.It is found that the predicted tunnel displacements by the RVM model closely match with the measured ones.The correlations of parameters have significant impacts on the uncertainty results.The uncertainty of tunnel displacement decreases while the reliability of the tunnel increases with the increases of the negative correlations among rock mass parameters.When compared to the deterministic method,the proposed approach is more rational and scientific,and also conformed to rock engineering practices.  相似文献   

Physical modelling and numerical analysis of slope instability subjected to reservoir impoundment of the Three Gorges     

Shaojun Li  Qiancheng Sun  Zhenhua Zhang  Xianqi Luo 《Environmental Earth Sciences》2018,77(4):138

Increasing attention is being given to investigations of failure mechanisms of unstable slopes influenced by water fluctuation during impoundment, such as in the case of reservoir landslides surrounding the Three Gorges, China. In this paper, two typical soil slopes with thin and thick rear edges are considered in a systematic investigation of the large-scale landslides triggered by reservoir impoundment. Physical model test, centrifugal modelling and numerical analysis are presented; these show the deformation evolution process and are aimed at obtaining the physical and mechanical laws that govern deformation and failure of such typical slopes during increasing water levels in a reservoir. The results indicate that deformation of the soil slopes triggered by impoundment can be divided into three stages: the rapid deformation stage, the slow development stage and the convergence creep stage. Moreover, deformation increases rapidly in the initial water level increase, and deformation growth slows with continued increase in water levels. Although the failure modes of the two typical slopes were not identical, the deformation in both started when soil softening occurred, suggesting that the initial phase of water level rise is likely the most dangerous phase with respect to soil slope stability. The results are likely to provide a foundation for further disaster mechanism studies, as well as disaster prevention and reinforcement design of reservoir soil slopes.  相似文献   

PROSAIL模型模拟下的植被指数土壤调节能力比较与适用环境分析   总被引：1，自引：0，他引：1  

徐雯靓  王少军 《遥感学报》2014,18(4):826-842

为了消除土壤背景信息对植被指数的影响,近几十年发展了土壤调节植被指数系列(SAVI family)。在不同环境条件下,不同指数抗土壤影响的能力不同。在总结了以消除土壤影响为目的的植被指数建立过程的基础上,利用PROSAIL辐射传输模型模拟的两组数据集,比较分析了NDVI、SAVI、TSAVI、MSAVI、OSAVI和GESAVI在不同叶面积指数(LAI)对应不同土壤背景的情况下抗土壤干扰、表达植被信息的能力,指出了不同植被指数应用的最适环境条件。结合植被指数—信噪比图,将这6种植被指数分成3类:在中低LAI值下,若植被覆盖度均匀,OSAVI和TSAVI有较强的消除土壤影响、表达植被信息的能力;当区域LAI分布不均、植被类型混杂时,MSAVI在表达植被信息时具有较好的稳定性。根据每类植被指数的特征,利用MODIS-VI和MODIS-LAI产品初步验证了上述结论的有效性。  相似文献   

Integrity monitoring of fixed ambiguity Precise Point Positioning (PPP) solutions     

Altti Jokinen  Shaojun Feng  Wolfgang Schuster  Washington Ochieng  Chris Hide  Terry Moore 《地球空间信息科学学报》2013,16(3):141-148

Traditional positioning methods, such as conventional Real Time Kinematic (cRTK) rely upon local reference networks to enable users to achieve high-accuracy positioning. The need for such relatively dense networks has significant cost implications. Precise Point Positioning (PPP) on the other hand is a positioning method capable of centimeter-level positioning without the need for such local networks, hence providing significant cost benefits especially in remote areas. This paper presents the state-of-the-art PPP method using both GPS and GLONASS measurements to estimate the float position solution before attempting to resolve GPS integer ambiguities. Integrity monitoring is carried out using the Imperial College Carrier-phase Receiver Autonomous Integrity Monitoring method. A new method to detect and exclude GPS base-satellite failures is developed. A base-satellite is a satellite whose measurements are differenced from other satellite’s measurements when using between-satellite-differenced measurements to estimate position. The failure detection and exclusion methods are tested using static GNSS data recorded by International GNSS Service stations both in static and dynamic processing modes. The results show that failure detection can be achieved in all cases tested and failure exclusion can be achieved for static cases. In the kinematic processing cases, failure exclusion is more difficult because the higher noise in the measurement residuals increases the difficulty to distinguish between failures associated with the base-satellite and other satellites.  相似文献   

Applications of three DNA barcodes in assorting intertidal red macroalgal flora in Qingdao, China     

ZHAO Xiaobo  PANG Shaojun  SHAN Tifeng  LIU Feng 《中国海洋大学学报(英文版)》2013,12(1):139-145

This study is part of the endeavor to construct a comprehensive DNA barcoding database for common seaweeds in China. Identifications of red seaweeds, which have simple morphology and anatomy, are sometimes difficult solely depending on morphological characteristics. In recent years, DNA barcode technique has become a more and more effective tool to help solve some of the taxonomic difficulties. Some DNA markers such as COI (cytochrome oxidase subunitⅠ) are proposed as standardized DNA barcodes for all seaweed species. In this study, COI, UPA (universal plastid amplicon, domain V of 23S rRNA), and ITS (nuclear internal transcribed spacer) were employed to analyze common species of intertidal red seaweeds in Qingdao (119.3 -121 E, 35.35 -37.09 N). The applicability of using one or a few combined barcodes to identify red seaweed species was tested. The results indicated that COI is a sensitive marker at species level. However, not all the tested species gave PCR amplification products due to lack of the universal primers. The second barcode UPA had effective universal primers but needed to be tested for the effectiveness of resolving closely related species. More than one ITS sequence types were found in some species in this investigation, which might lead to confusion in further analysis. Therefore ITS sequence is not recommended as a universal barcode for seaweeds identification.  相似文献