GPS接收机内部噪声水平测试方法研究     

苏玉瑞  姬洪亮  王晓南 《测绘与空间地理信息》2014,(12)

阐述了在GPS精度鉴定系统中,针对短基线快速检核GPS接收机内部噪声水平测试方法进行研究,并结合试验验证了方法的可靠性.  相似文献   

Late Holocene monsoon climate as evidenced by proxy records from a lacustrine sediment sequence in western Guangdong,South China     

《Journal of Asian Earth Sciences》2014

The study of a 300-cm-thick exposed lacustrine sediment section in the Hedong village in Zhaoqing area which is located in sub-tropical west Guangdong Province in South China, demonstrates that the lacustrine sedimentary sequence possibly contains evidence for exploring variation of Asian monsoon climate. Multi-proxy records, including the humification intensity, total organic carbon, and grain size fractions, reveal a general trend towards dry and cold conditions in the late Holocene that this is because of a decrease in solar insolation on an orbital scale. Three intensified Asian summer monsoon (ASM) intervals (∼3300–3000 cal yr BP, ∼2600–1600 cal yr BP, and ∼900–600 cal yr BP), and three weakened ASM intervals (∼4000–3300 cal yr BP, ∼3000–2600 cal yr BP, and ∼1600–900 cal yr BP) are identified. Our humification record (HD_cal) shows a good correlation on multi-centennial scale with the tree ring Δ¹⁴C record, a proxy of solar activity. A spectral analysis of HD_cal reveals four significant cycles, i.e., ∼1250 yr, 300 yr, 110 yr, and 70 yr, and most of these cycles are related to the solar activity. Our findings indicate that solar output and oceanic–atmospheric circulation probably have influenced the late Holocene climate variability in the study region.  相似文献   

连续小波变换识别位场场源法的噪声影响分析与尺度因子的选择     

刘彩云  ;姚长利 《物探与化探》2014,(3):527-533

为提高连续小波变换识别位场场源准确度,研究噪声对场源识别结果的影响和尺度因子优选方法问题。根据连续小波变换识别位场场源的基本原理,用该方法对不同噪声水平的合成数据进行场源识别,分析噪声对于场源识别结果的影响,研究小波变换的尺度因子对噪声压制的效果,讨论连续小波变换进行场源识别时尺度因子的选取方法。理论模型和实测资料场源识别结果表明,噪声会降低连续小波变换场源识别结果的准确度,笔者提出的尺度因子优选方法能有效压制噪声干扰,提高场源识别结果的准确度。  相似文献   

论气候变暖背景下干旱和干旱灾害风险特征与管理策略简   总被引：2，自引：0，他引：2  

Zhang Qiang  Han Lanying  Zhang Liyang  Wang Jingsong 《地球科学进展》2014,29(1):80-91

The drought is a most severe natural disaster worldwide, which leads to great risk in human being. The drought disaster and risk have more prominent because of obvious climatic warming in the last hundred years. At present, the understanding of the internal laws of the occurrence of drought and drought risk is not comprehensive, and the recognition of the characteristics of the drought and drought risk under climatic warming is obscure. In this paper, we summarized systematically the domestic and overseas research progress of the drought and drought disaster risk, introduced the principle of the drought disaster transfer process and the essential features of drought disaster, analyzed synthetically the main characteristics and interactions among the key factors of the drought disaster risk, discussed the effect of climatic warming on drought and drought disaster risk, and probed into the basic requirement of drought disaster risk management. Above all, we provide the main protective measurements of the drought disaster and the main strategy of drought disaster risk management.  相似文献   

陆生植物氮同位素组成与气候环境变化研究进展   总被引：3，自引：0，他引：3  

刘贤赵  张勇  宿庆  田艳林  王庆  全斌 《地球科学进展》2014,29(2):216-226

近年来,由于植物氮同位素组成(δ15N)记载了气候环境变化的信息,因而被广泛应用于全球变化研究中,成为古气候环境再造和了解现代气候环境变化信息的有力工具。然而,人们对气候环境引起的δ15N变化及其指示的气候环境意义并不完全清楚,这就有可能限制植物δ15N在古气候环境变化等领域研究中的应用。在概述植物氮同位素分馏和植物不同氮源的氮同位素分布的基础上,分析了温度、降水、大气CO2浓度和海拔高度等气候环境因子对陆生植物δ15N的影响以及它们的关系。指出了目前研究中存在的问题及其研究前景,认为在全球变化研究中利用植物氮同位素技术不仅可以重建古气候环境(如重建大气CO2浓度变化),揭示历史时期温度、降水的变化,而且还可以在一定的时间和空间上综合反映生态系统氮循环的特征。  相似文献   

Research Progress in Responses of Modern Terrestrial Plant Carbon Isotope Composition to Climate Change   总被引：1，自引：0，他引：1  

Liu Xianzhao  Zhang Yong  Su Qing  Tian Yanlin  Quan Bin  Wang Guoan 《地球科学进展》2014,29(12):1341-1354

Global climate change has been one of the most concerned environmental problems in the world since the 1980s. Since stable carbon composition (¹³C) in plant tissues can record abundant information on climate changes, it has been widely used as an important climate proxy in global change studies and becomes a powerful tool for obtaining paleoclimate information, understanding paleoenvironment reconstruction and modern climate change, and predicting future climate trends. However, a lot of potential uncertainties have always involved in the reconstruction of paleoclimate and paleoenvironment by carbon isotope of the past period sediment or fossils. Among them, the most dominant uncertainty is due to our poor understanding of the relations between carbon isotope ratios of plants and climatic factors and the climatic and environmental significance indicated by modern plant ¹³C. This may limit the application of plant ¹³C in the study of climatic and environmental changes. Based on the Summary of plant ¹³C fractionation and carbon isotope distribution of different photosynthetic plants, the effects of environmental factors, e.g., temperature, precipitation, atmospheric CO₂ concentration, and altitude on terrestrial plant ¹³C and their relationships were reviewed in this paper, and the response mechanism of plant ¹³C to climate changes were also analyzed. Furthermore, the current existing problems and the future prospects in carbon isotope study were discussed. It is pointed out that strengthening some studies such as the response of C₄ plants ¹³C to climate environmental parameters, the transformation relation of different scale plant ¹³C, intersection and permeation of related disciplines, and various proxies and scientific method, will undoubtedly make us have a more accurate understanding of the climate history and eventually broaden the development of the field during the process of global change study by plant carbon isotope techniques.  相似文献   

利用H/V方法研究琼北火山区的浅表层地质变化特征     

曹佳俊  郭震  夏少红  张昌榕  吴晓阳  任鹏飞 《热带海洋学报》2022,41(1):184-193

海南琼北活火山作为华南沿海重要的第四纪火山, 一直受到国内外学者的广泛关注, 目前对该火山的形成演化已开展了大量深部地质结构的研究, 但对其表层地质结构特征仍然缺乏详细了解。水平-垂直频谱比法(简称H/V方法)已被广泛应用于浅表层地质结构的研究, 本文基于35个便携式微功耗地震仪组成的流动台阵观测数据, 采用经典全波场H/V_(full)和瑞利波椭圆率H/V_(Ray)分析方法, 获得了琼北火山区H/V曲线峰值频率(F₀)和放大倍数(A₀)的空间变化特征。琼北火山区H/V曲线峰值频率变化强烈, 以长流-仙沟断裂为界, 断裂西南侧很难从H/V曲线中获取清晰的F₀和A₀, 而断裂东北侧则存在明显的F₀和A₀。结合已有地质资料, 本文认为长流-仙沟断裂西南侧处于凹陷区, 其浅表层火山岩未发生明显的风化作用, 而东北侧位于隆起区域, 地表火山岩受到了比较严重的风化作用。这一研究结果表明, H/V方法可反映表层火山岩的风化状态, 火山岩出露场地H/V曲线的峰值频率和放大倍数随风化作用程度的增强而表现得更加明显。本研究为琼北火山区浅表火山岩风化状态和地震危险性评估提供了重要的信息支撑。  相似文献   

利用背景噪声的分形方法监控台站观测系统运行状态     

丁莉莎  马洁美  齐军伟  谢剑波  廖一帆  卢子晋  叶世山  劳谦  吕仲杭 《大地测量与地球动力学》2021,41(4):436-440

使用全国23个国家测震台站和17个实验台站地震计记录的背景噪声数据,研究特定尺度(限定频带内)的背景噪声特性,分析利用分形方法监测台站观测系统运行状态的可行性。结果表明,分形方法具有较强的时域性,定量化程度高、抗干扰能力强,基本不受观测系统参数约束,可用于台站观测系统运行状态检测,减少正常记录瞬间中断和引入人为干扰的情况。  相似文献   

沂沭断裂带深反射地震资料处理          下载免费PDF全文

罗文强  张尚坤  陈军  杨斌  马祥县  唐璐璐  梁吉坡  刘凤臣  仵康林  陈诚 《山东国土资源》2021,37(2)

地震时间剖面可以对地质目标进行精细刻画,但由于变质岩、侵入岩地区存在地质体不规则、地质界线间波阻抗差异不明显、断裂构造倾角高陡等特征,导致地震原始资料具有波场复杂、干扰波发育、资料信噪比低等特点。为获得客观反应实际地质情况的沂沭断裂带深反射地震剖面,通过对研究区原始地震资料细致分析,针对各种干扰波的不同特性特征,分别采取针对性压制措施,进行组合去噪,在压制干扰的同时最大限度保护了有效信号。本次地震资料处理以高保真和高信噪比为目标,通过边处理边解释不断优化处理流程和处理参数。在处理过程中对静校正、叠前去噪、速度场建立以及波场空间归位等关键工作进行了重点研究,最终获得了高品质地震叠加和偏移时间剖面。反射剖面首次揭示了沂沭断裂带及其两侧岩石圈精细结构,为研究沂沭断裂带深部结构及对资源、环境的影响提供了可靠的地震学依据。  相似文献   

甚宽频带地震计频域标定的噪声数据处理方法   总被引：2，自引：3，他引：2  

周云耀 《大地测量与地球动力学》2004,24(1):121-126

分析了频域标定中的噪声及传统数据处理方法，提出数据处理的本质是噪声处理的观点，探讨了不同噪声的不同处理方法，详细研究了长周期非线性漂移的噪声处理方法，有效地提高了频域标定精度。  相似文献