基于EMD小波阈值滤波的地磁数据去噪分析     

张敏  王喜珍  滕云田  胡星星  吴琼 《地震地磁观测与研究》2012,33(3):171-175

采用小波阈值滤波、经验模态分解滤波和基于经验模态分解的小波阈值滤波3种方法,对磁通门磁力仪观测数据进行去噪,有效去除或抑制郫县地震台地磁数据的地电干扰.  相似文献   

A numerical study of the barotropic tides and tidal energy distribution in the Indonesian seas with the assimilated finite volume coastal ocean model     

Yang Ding  Xianwen Bao  Huaming Yu  Liang Kuang 《Ocean Dynamics》2012,62(4):515-532

The tides and tidal energetics in the Indonesian seas are simulated using a three-dimensional finite volume coastal ocean model. The high-resolution coastline-fitted model is configured to better resolve the hydrodynamic processes around the numerous barrier islands. A large model domain is adopted to minimize the uncertainty adjacent to open boundaries. The model results with elevation assimilation based on a simple nudge scheme faithfully reproduced the general features of the barotropic tides in the Indonesian Seas. The mean root-mean-square errors between the observed and simulated tidal constants are 2.3, 1.1, 2.4, and 1.5 cm for M₂, S₂, K₁, and O₁, respectively. Analysis of the model solutions indicates that the semidiurnal tides in the Indonesian Seas are primarily dominated by the Indian Ocean, whereas the diurnal tides in this region are mainly influenced by the Pacific Ocean, which is consistent with previous studies. Examinations of tidal energy transport reveal that the tidal energy for both of the simulated tidal constituents are transported from the Indian Ocean into the IS mainly through the Lombok Strait and the Timor Sea, whereas only M₂ energy enters the Banda Sea and continues northward. The tidal energy dissipates the most in the passages on both sides of Timor Island, with the maximum M₂ and K₁ tidal energy transport reaching about 750 and 650 kW m^–1, respectively. The total energy losses of the four dominant constituents in the IS are nearly 338 GW, with the M₂ constituent dissipating 240.8 GW. It is also shown that the bottom dissipation rate for the M₂ tide is about 1–2 order of magnitudes larger than that of the other three tidal components in the Indonesian seas.  相似文献   

A two-dimensional morphological model based on next generation circulation solver II: Application to Caofeidian, Bohai Bay, China     

Cui-Ping Kuang  Si-Yu Chen  Yu Zhang  Jie GuLing Deng  Yi PanJing Huang 《Coastal Engineering》2012,59(1):14-27

This paper is a companion of a two-part papers on the development of a two-dimensional morphological model—CurWaC2D-Sed, based on next generation circulation solver. In this paper, the model developed in paper I is applied to the large-scale construction of near-harbor industrial zone with deep water harbor by reclamation in Caofeidian, Bohai Bay, which is a typical sandbar-lagoon bay-type tidal inlet system. Characteristics of tides, currents, waves and sediments in Caofeidian are firstly analyzed with field data from comprehensive field observations carried out in 2008. These data are then used for model calibration and validation, showing a good agreement between simulated results and field measurements for tides, currents and suspended sediments. The verified model is applied to study the effects of the construction of Caofeidian embankment and the on-going engineering scheme on hydrodynamics and sediment transports as compared with no constructions under three representative tide conditions and their combinations with normal and strong waves as well as on morphology evolution. The simulated results indicate that the present scheme leads to morphological changes in Caofeidian with acceptable rates of erosion and sedimentation. However, some attentions should be paid to erosion at offshore wharf in front of Caofedian foreland which may lead to potentially increasing landslide risks due to steep slope and sedimentation in Laogonggou creek.  相似文献   

Association between air pollution and chronic diseases among the elderly in China     

Su Liu  Zhijun Yan  Yan Liu  Qiuju Yin  Lini Kuang 《Natural Hazards》2017,89(1):79-91

With the development of Chinese economies, air pollution is becoming more and more serious, which greatly affects the residents’ daily life and health. Meanwhile, China’s aging population is growing rapidly and bringing a number of social problems. We used the data of CHARLS and analyzed the relationships between air pollution and chronic diseases among the elderly in China. The results showed that air pollution had significant adverse effects on the health of the elderly, especially on diabetes and heart diseases. The subgroup analysis showed that female is more sensitive to air pollution than male, while different age groups are significantly sensitive to different chronic diseases.  相似文献   

Origin and Distribution Factors of Sour Gases in Natural Gas Reservoirs in the Amu Darya Right Bank Block,Turkmenistan     

Qi Li  Liang Xu  Dongqin Kuang 《地球科学进展》2017,32(11):1183-1192

Through the analysis of original carbon isotopes in the blocks on the right bank of the Amu Darya River, Turkmenistan, it can be firstly concluded that the carbon dioxide (CO₂) in the sour gas reservoirs belongs to the inorganic-origin gas. The origin of hydrogen sulfide (H₂S) in the Amu Darya Right Bank Block is thermochemical sulfate reduction from the detailed analysis of hydrocarbon source rocks data, reservoir characteristics, vitrinite reflectance of organic matter, and sour gas content. Then, the factors affecting the distribution of sour gases in the Amu Darya Right Bank Block were investigated by the analysis of conventional sour gas distribution factors including geological structure, fracture and fault, caprock integrity, sedimentary facies, reservoir types, lithofacies, the source of sulfur and so on. The following basic findings were achieved: ① The basement rift in the study area is conductive to the distribution of CO₂. The caprock integrity contributes to the concentration of CO₂. The gas reservoirs in the biological dike reefs, patch reefs and overthrust zones usually have medium CO₂ content. ② The geological structure and fracture caused the complexity of the distribution of H₂S. The gypsum-salt rock in upper Jurassic-Tithonian is an important sulphur source, and the main hydrocarbon source rocks are also the major sulfur source of H₂S gas reservoirs. Furthermore, the giant gypsum layers in the middle-upper Jurassic Callovian-Oxfordian and the upper Jurassic-Tithonian are conductive to preservation of H₂S, and the small openings and holes in the reservoir is also correlative to the distribution of H₂S. ③ The H₂S in the study area is mostly distributed in the formations with the geothermal temperature of higher than 100 ℃. The open platform deep-water sedimentary facies are harmful to the formation of H₂S. The patch reef and overthrust zones belong to the belts of low H₂S content, however, the biological dike reef zones belong to the belts of medium-high H₂S content. However, the origin and distribution factors of sour gases in natural gas reservoirs were obtained. At the same time, it was pointed out that more necessary and accurately quantitative research is still needed to determine the origin and distribution of acid gases in the Amu Darya Right Bank Block, Turkmenistan.  相似文献   

Singularity-free expression of magnetic field of cuboid under undulating terrain     

Xing-Tao Kuang  Hai Yang  Xiao-Ying Zhu  Wei Li 《应用地球物理》2016,13(2):238-248

Most of the current computing methods used to determine the magnetic field of a uniformly magnetized cuboid assume that the observation point is located in the upper half space without a source. However, such methods may generate analytical singularities for conditions of undulating terrain. Based on basic geomagnetic field theories, in this study an improved magnetic field expression is derived using an integration method of variable substitution, and all singularity problems for the entire space without a source are discussed and solved. This integration process is simpler than that of previous methods, and final integral results with a more uniform form. ΔT at all points in the source-free space can be calculated without requiring coordinate transformation; thus forward modeling is also simplified. Corresponding model tests indicate that the new magnetic field expression is more correct because there is no analytical singularity and can be used with undulating terrain.  相似文献   

沉积学研究热点与进展:第32届国际沉积学会议综述^*          下载免费PDF全文

朱筱敏  李顺利  潘荣  谈明轩  陈贺贺  王星星  陈锋  张梦瑜  侯冰洁  董艳蕾 《古地理学报》2016,18(5):699-716

第32届国际沉积学会议(32nd IAS Meeting of Sedimentology)于2016年5月23—25日在摩洛哥马拉喀什召开, 来自43个国家和地区的360余名学者参加了本次会议。综述研究表明, 会议研究热点为陆相沉积环境、浅水沉积与滨岸潮汐、深水沉积与事件沉积、碳酸盐与化学岩沉积、沉积过程与盆地分析、成岩作用与油气储集层等研究领域。会议主要研究进展表现为: 波浪再悬浮作用(wave resuspension)与异重流(hyperpycnal flows)是陆架边缘斜坡快速进积的主要因素;海啸发生周期为14~35, ka, 后积层理(backset-bedding)为海啸沉积识别标志;海底滑坡多由海底地震、天然气水合物泄露等触发, 其块状搬运沉积物(MTD)包括滑塌头部、滑动底面、滑塌主体以及滑塌后期浊流沉积;玄武岩等基岩的风化作用提供硅与富镁碱性水, 有利于菱沸石与白云石的形成;受构造作用影响, 隆起剥蚀区与沉积区可互为转化;物源性质、供给量及搬运或分散过程控制了沉积面貌(源汇系统);构造活动直接控制可容纳空间变化、地貌变化、源区剥蚀速率、沉积物供应速率等。最后, 本文对比了中外沉积学发展差异, 讨论了中国沉积学发展方向。  相似文献   

国内外公共服务设施空间布局研究进展     

程顺祺  祁新华  金星星  李达谋  林涵 《热带地理》2016,36(1):122-131

按照纵向发展时序对国内外公共服务设施空间布局研究的视角、方法和主题进行了梳理。结果表明：国外研究主题历经了区位选择和布局模式、空间布局的公平性和可达性、布局的社会分异及其形成机制等的演变;研究视角从单纯的计量地理发展到与经济学、社会学等多学科交叉;研究方法从构建模型发展到与GIS结合等多种方法集成等。相比之下,国内研究差距明显,主要表现在研究视角欠缺多学科的交叉融合,方法多借鉴国外,缺乏创新,主题较为局限。最后提出未来研究应该多关注以下5方面：丰富可达性的内涵进行公平性度量;在以人为本的基础上整合配套多设施协同布局;注重设施的应时性和可变性;在大数据背景下开展小尺度的实证研究;植根中国实际,研究对象转向农村地区以及城市边缘区。  相似文献   

Potential promoted productivity and spatial patterns of medium- and low-yield cropland land in China   总被引：2，自引：1，他引：1  

Huimin Yan  Yongzan Ji  Jiyuan Liu  Fang Liu  Yunfeng Hu  Wenhui Kuang 《地理学报(英文版)》2016,26(3):259-271

With a continuously increasing population and better food consumption levels, improving the efficiency of arable land use and increasing its productivity have become fundamental strategies to meet the growing food security needs in China. A spatial distribution map of medium- and low-yield cropland is necessary to implement plans for cropland improvement. In this study, we developed a new method to identify high-, medium-, and low-yield cropland from Moderate Resolution Imaging Spectroradiometer (MODIS) data at a spatial resolution of 500 m. The method could be used to reflect the regional heterogeneity of cropland productivity because the classification standard was based on the regionalization of cropping systems in China. The results showed that the proportion of high-, medium-, and low-yield cropland in China was 21%, 39%, and 40%, respectively. About 75% of the low-yield cropland was located in hilly and mountainous areas, and about 53% of the high-yield cropland was located in plain areas. The five provinces with the largest area of high-yield cropland were all located in the Huang-Huai-Hai region, and the area amounted to 42% of the national high-yield cropland area. Meanwhile, the proportion of high-yield cropland was lower than 15% in Heilongjiang, Sichuan, and Inner Mongolia, which had the largest area allocated to cropland in China. If all the medium-yield cropland could be improved to the productive level of high-yield cropland and the low-yield cropland could be improved to the level of medium-yield cropland, the total productivity of the land would increase 19% and 24%, respectively.  相似文献   

Strategic transformation of regionalization for the agricultural comprehensive development: The example of Ningxia Hui Autonomous Region in China     

Wenjiao Shi  Yunfeng Hu  Xiaoli Shi  Zong Wang  Huimin Yan  Ziwei Xu  Bo Ren  Wenhui Kuang  Xinliang Xu  Weiming Cheng  Yan Chen  Dongbo Wu 《地理学报(英文版)》2016,26(12):1675-1688

Strategic transformation of regionalization for agricultural comprehensive development (ACD) was presented by the Ministry of Finance of the People’s Republic of China (MOF) in 2014. The regionalization is the premise and basis of the sustainable development and improved competitiveness for agriculture. Based on the environmental resources related to agriculture, such as cropland, climate, water resources, terrain, geomorphology, patterns of the ACD projects, distribution of ecological planning, etc., we devised 13 indices using the geographic comprehensive regionalization method. The indices took into account a combination of dynamic and static, qualitative and quantitative, as well as agricultural and ecological factors. The strategic transformation of regionalization for the ACD in Ningxia Hui Autonomous Region of China was performed; seven types were included: prioritized regions, prioritized and restricted regions, protected regions, protected and restricted regions, restricted and prioritized regions, restricted and protected regions, and restricted regions. A further 24 subtypes were used based on locations and ecological zones. The regionalization results showed that prioritized regions were mainly in northern Ningxia, the most suitable area for agriculture. The protected and restricted regions were in central and southern Ningxia. In the central part, drought was the limiting factor for agriculture, and water conservation projects there should be supported. The ecological environment is fragile in southern Ningxia, so there is a need for ecologically sound agriculture to be developed in this region. Such regionalization could achieve two goals, namely agricultural conservation and eco-environmental protection. It was performed following the requirement for scientific regionalization to include three types of regions (prioritized regions, protected regions, and restricted regions), and was applied at the township scale in a provincial or autonomous region for the first time. The results provide both guidance for the strategic transformation of the ACD in Ningxia, and a reference for similar work in other provinces.  相似文献