基于Poynting矢量的地震照明分析     

杨弘宇  刘继承  段玉波 《吉林大学学报(地球科学版)》2017,47(1)

地震照明分析能够定量分析影响逆时偏移成像质量的因素。文章基于Poynting矢量方法进行地震定向照明分析及成像补偿方法研究,利用Poynting矢量进行波场传播角度分解,通过计算不同入射及散射波方向的部分照明建立局部照明矩阵。该矩阵包含了照明分析中波与地质结构相互作用所涉及的所有角度信息,可以方便地分析目标附近所有可能的入射波和散射波对局部照明的贡献。根据局部照明矩阵可以获得对地下结构的照明描述、采集倾角响应,并依此进行成像补偿计算。以SEG/EAGE模型作为数值计算实例,进行基于Poynting矢量的照明分析及成像补偿,有效地提高了成像质量。该方法为角度域逆时偏移成像校正及分辨率分析等提供了高效的处理手段。  相似文献   

Coagulation performance and microstructural morphology of a novel magnetic composite coagulant for pre-treating landfill leachate     

Z. Liu  X. Duan  P. Zhan  R. Liu  F. Nie 《International Journal of Environmental Science and Technology》2017,14(11):2507-2518

A novel magnetic composite coagulant, prepared from nano-Fe₃O₄ and poly-aluminum chloride, was introduced to pre-treat mature landfill leachate. The coagulation performance of the coagulant as well as its microstructural morphology was discussed. Coagulation experimental results revealed that the coagulation performance of the landfill leachate using the new coagulant was better than that using poly-aluminum chloride alone, with COD and color removals above 60 and 68%, respectively. Based on the analysis of three-dimensional excitation–emission matrix spectrum, the fluorescence signals of treated leachate are totally reduced by the magnetic composite coagulant. The components of dissolved organic matters in the wastewater are removed in different degrees. Fourier transform infrared spectra analysis shows that the magnetic composite coagulant, which is a multi-core polymer with hydroxyl ligands and nano-Fe₃O₄, has a complex valence and crystal structure. Besides, X-ray diffraction pattern analysis indicates that the chemical composition of the magnetic composite coagulant is not changed significantly, which has comprehensively combined the chemical characteristics of both nano-Fe₃O₄ and poly-aluminum chloride, whereas the specific surface area of the novel magnetic composite coagulant effectively increased by nano-Fe₃O₄ particles under the analysis of scanning electron microscope spectral. The specific surface area analysis indicates that the magnetic composite coagulant is interconnected by narrow cracks and holes and has a high specific surface area and developed pore structure, which is also similar to the typical porous-type materials. Therefore, the nano-Fe₃O₄ compounded with poly-aluminum chloride leads to a larger specific surface, smaller average pore diameter, and more pore volume of the novel coagulant.  相似文献   

Combined spheropolyhedral discrete element (DE)–finite element (FE) computational modeling of vertical plate loading on cohesionless soil     

Christopher T. Senseney  Zheng Duan  Boning Zhang  Richard A. Regueiro 《Acta Geotechnica》2017,12(3):593-603

This paper presents a combined spheropolyhedral discrete element (DE)–finite element (FE) computational approach to simulating vertical plate loading on cohesionless soils such as gravels. The gravel particles are modeled as discrete elements, and the plate is modeled as a deformable FE continuum. The simulations provide a meaningful step toward better understanding how deformable bodies transmit loads to granular materials. The DE–FE contact algorithm is verified through comparison with an analytical solution for impact between two symmetric bars. A parametric study is conducted to ensure boundary effects are not significantly influencing the simulations. Numerical simulations are compared to experimental test results of lightweight deflectometer loading on a gravel base course with satisfactory agreement. Future developments of the approach intend to simulate wheel loading of military aircraft on unsurfaced airfields.  相似文献   

南秦岭竹溪县天宝乡粗面岩地球化学特征与铌成矿     

杨成  刘成新  刘万亮  万俊  段先锋  张众 《岩石矿物学杂志》2017,36(5):605-618

南秦岭造山带北大巴山东段大面积出露早志留世粗面岩,夹于早志留世梅子垭组(S_1m)下部层位含炭粉砂质板岩之中,整体呈北西-南东向展布。这套粗面质火山岩与铌矿关系密切。竹溪县天宝铌矿床产出于火山喷发沉积韵律的中下部层位,赋矿岩石以粗面质熔结凝灰岩为主。粗面质熔岩地球化学数据显示其富碱质,稀土元素总量高且轻稀土元素明显富集,高场强元素Nb、Ta、Zr、Hf等富集,Sr、P、Ti等亏损,具有类似于OIB的地球化学性质,来源于幔源玄武质岩浆的演化,是形成于大陆裂谷环境的低压型粗面岩。矿体粗面岩类(熔结凝灰岩)与非矿体粗面岩(粗面质熔岩)相比,具有略低的SiO_2含量,高的Al_2O_3、K_2O、CaO含量,低的P_2O_5含量,更为富集的高场强元素(Nb、Ta、Zr、Hf)和轻稀土元素(La、Ce),更强的负Eu异常、正Ce异常,略强的P、Ti负异常以及更高的挥发分(F、CO_2)含量。天宝铌矿含铌矿物为易解石,产出于早期矿物的边缘、裂隙或晚期细脉中,成矿阶段处于岩浆作用的晚期。铌的富集与挥发分(F、CO_2等)的运移、保存条件密切相关。该铌矿为火山岩型稀有金属矿床,兼具岩浆型和岩浆热液型矿床特征,与庙垭和杀熊洞铌-稀土矿床属同一成矿系列的不同类型矿床。  相似文献   

In situ major and trace element analysis of amphiboles in quartz monzodiorite porphyry from the Tonglvshan Cu–Fe (Au) deposit,Hubei Province,China: insights into magma evolution and related mineralization     

Deng-Fei?Duan  Shao-Yong?JiangEmail authorView author&#;s OrcID profile 《Contributions to Mineralogy and Petrology》2017,172(5):36

The Tonglvshan deposit is the largest Cu–Fe (Au) skarn deposit in the Edong district, which is located in the westernmost part of the Middle and Lower Yangtze River metallogenic belt, China. In this study, we performed a detailed in situ analysis of major and trace elements in amphiboles from the ore-related Tonglvshan quartz monzodiorite porphyry using electron microprobe (EMPA) analysis and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Two distinct populations of amphiboles, which can be distinguished by their aluminum content, are found in the quartz monzodiorite porphyry. The low-aluminum (Low-Al) amphiboles are subhedral or anhedral and formed at 46.3–73.5 MPa and 713–763 °C. In contrast, the high-aluminum (High-Al) amphiboles are euhedral and formed at 88–165 MPa and 778–854 °C. Some euhedral amphiboles are partially or completely replaced by Low-Al amphibole. The compositions of parental melts in equilibrium with the High-Al amphibole (Melt 1) and Low-Al amphibole (Melt 2) were computed by applying solid/liquid partition coefficients. This modeling shows that magma in equilibrium with High-Al amphibole (Melt 1) underwent 40% fractional crystallization of amphibole, plagioclase and apatite at a depth of ~5 km to evolve to magma in equilibrium with Low-Al amphibole (Melt 2). Copper enrichment occurred in the magma after undergoing fractional crystallization. The magma had a high oxygen fugacity, increasing from NNO + 1 (Melt 1) through NNO + 2 to HM (Melt 2), which could have prevented the loss of Cu (and possibly Au) to sulfide minerals during crystallization. Finally, the evolved magma intruded to shallower depths, where it presumably exsolved aqueous ore-forming fluids. Therefore, the large Cu–Fe–Au reserves of the Tonglvshan deposit can likely be attributed to a combination of controlling factors, including high oxygen fugacity, fractional crystallization, fluid exsolution, and a shallow emplacement depth.  相似文献   

The assessment of traffic accident risk based on grey relational analysis and fuzzy comprehensive evaluation method   总被引：1，自引：1，他引：0  

Yaolong Liu  Xiaoli Huang  Jin Duan  Huaming Zhang 《Natural Hazards》2017,88(3):1409-1422

The traffic accident risk includes three aspects, traffic accident probability, traffic accident severity, and traffic accident trend respectively. In this paper, nine indicators are selected to evaluate the traffic accident risk. The grey relational analysis method was used to determine the weights, and the fuzzy comprehensive evaluation method was used to calculate the risk. These methods were applied to assess the comprehensive risk of traffic accident in 31 provinces in China. The results show that the average value of traffic accident risk is 55.17. Nine provinces which are located in the northwest area and southeast area belong to the high-risk level. The medium-risk areas are widely distributed in the central, northeast, and southwest regions. The low-risk areas are Jilin, Neimenggu, Guizhou, and Beijing. The results have great significance for the measurement and management of regional traffic accident risk.  相似文献   

Petrogenesis of Luchuba and Wuchaba granitoids in western Qinling: geochronological and geochemical evidence     

Kong  Juanjuan  Niu  Yaoling  Duan  Meng  Zhang  Yu  Hu  Yan  Li  Jiyong  Chen  Shuo 《Mineralogy and Petrology》2017,111(6):887-908

Mineralogy and Petrology - The West Qinling Orogenic Belt (WQOB) is a major portion of the Qinling-Dabie-Sulu Orogen and holds essential information for understanding the prolonged evolution of the...  相似文献   

Preliminary Comparison of the CMA, ECMWF, NCEP, and JMA Ensemble Prediction Systems   总被引：1，自引：0，他引：1       下载免费PDF全文

DUAN Mingkeng  MA Juhui  WANG Panxing 《Acta Meteorologica Sinica》2012,26(1):26-40

Based on The Observing System Research and Predictability Experiment (THORPEX) Interactive Grand Global Ensemble (TIGGE) dataset,using various verification methods,the performances of four typical ense...  相似文献   

近30年京津冀地区冰雹的气候特征和突变分析   总被引：7，自引：0，他引：7  

闵晶晶  曹晓钟  段宇辉  刘还珠  王式功 《气象》2012,38(2):189-196

基于1979—2008年京津冀地区175个气象站的冰雹观测资料,应用气候趋势系数、倾向率、集中度和集中期,以及连续功率谱等方法,分析了京津冀地区及4个划分关键区冰雹发生的多时间尺度变化特征和变化趋势,并运用蒙特卡罗方法检验了气候趋势系数的显著性。结果表明：近30年该地区的冰雹有明显减少趋势,北部地区比南部地区减少幅度要大,山地区域比平原地区减少幅度大;基本上都存在2.0～2.5年的变化周期,该地区冰雹的发生具有准两年周期振荡的特征;南部平原冰雹发生的集中度最大,该区冰雹在年内发生时间最为集中;南部平原集中期较早,出现在6月初,其他几个关键区冰雹主要发生在6月底到7月初。应用气候要素累计距平曲线、Yamamoto方法进行了气候突变分析,结果表明京津冀地区冰雹在1993年发生了减少的突变,山地区域尤为显著。  相似文献   

1918—2010年天津降水指数变化特征   总被引：5，自引：0，他引：5       下载免费PDF全文

段丽瑶  刘爱霞  史珺 《气候变化研究进展》2012,8(3):171-177

利用天津1918—2010年逐日降水资料,分析了天津7个降水指数的长期变化趋势。结果发现:天津年降水量和降水日数年际差异较大,没有显著的趋势性变化。从1980年开始天津降水量和日数开始变小(少),方差也变小,四季中秋季降水量呈显著的增加趋势,夏季呈减少趋势,冬、春季变化较小。各极端降水指数中,均表现为线性趋势不明显,年际变化较大,20世纪90年代以来降水强度偏小,但呈缓慢的增加趋势,大雨日数也处于偏少阶段,大雨贡献率偏小,并呈减小趋势。四季中秋季连续5 d最大降水量呈显著的增加趋势,减少了秋季干旱的发生,最长连续无降水日数多发生在冬春季,近年来有增加的趋势。  相似文献