模拟雷电流冲击金属材料的金相组织分析

金相组织分析是雷电灾害鉴定的重要方法之一.通过模拟雷电流冲击的不同金属材料试验,并对其冲击材料进行金相组织分析,重点从材料微观结构变化研究雷电流对金属材料的影响.结果表明:模拟雷电流冲击后的金属材料其金相组织结构发生明显变化(缺陷增多);不同金属材料冲击后内部金相组织结构变化有明显差异;相同材质的金属材料冲击后,其金相组织结构变化幅度与其截面积大小成反比.     

欧盟航空碳税及其国际影响

根据当前欧盟征收国际航空碳税政策的国际环境,介绍欧盟航空碳税的历史沿革、具体政策、二氧化碳排放监测方法,就各国反应及其国际影响进行分析.欧盟航空碳税可能会导致全球航空业成本增加,并最终转嫁给消费者;欧盟航空碳税对发达国家航空公司影响较小,而对发展中国家的航空公司影响较大.鉴于欧盟航空碳税对中国航空业的影响,建议尽早制定相关的碳排放标准,维护中国应有的发展权与话语权.     

第二次全国土地调查成果质量检查系统开发

采用ArcGIS Engine,基于.NET软件开发环境,集成数据库、地理信息系统等多种技术,基于质检细则,并进行规则配置,开发第二次全国土地调查成果质量检查系统,通过全国免费使用,大幅提高了工作效率,确保了全国2800多个县市的第二次全国土地调查成果的规范一致和正确。本成果对土地利用数据质量的检查方式和方法,做了很好的探索和尝试,可以应用于今后每年的土地变更调查、国家土地利用规划数据汇交的数据质量检查工作中。     

骊山凸起隆升的时限及其地质意义

根据渭河盆地灞河期和游河期的地层沉积特征及分布范围,推断骊山凸起的隆升时期为晚中新世,游河期渭河盆地形成了西安凹陷和固市凹陷两个沉积中心,现今渭河盆地凸起和凹陷的并存的地貌格局很可能自晚中新世就已经形成。渭河盆地周缘在8Ma左右存在一次强烈区域隆升事件,对秦岭的隆升有显著影响。     

岩溶关键带及其碳循环研究进展

岩溶关键带的范畴包含了大气-(降水)-植被-土壤-裂隙-基岩-水组成的“碳-水-钙”循环强烈的表层岩溶带以及岩溶管道-洞穴-地下河-隔水层组成的巨大岩溶地下空间,岩溶关键带碳循环是岩溶地球系统科学研究的前沿方向。总结概括了岩溶地球系统科学发展至今的岩溶关键带范畴内碳循环及其对大气CO2源汇效应的研究成果,包括早期碳运移模型、当前主流的区域岩溶碳汇量的计算方法和结果以及“生物碳泵”的新发现等,讨论了当前岩溶碳循环研究框架过于单一或不一致以及碳周转时间尺度等问题,提出应对岩溶关键带碳输入、赋存以及碳输出的各个环节做出系统化监测,通过联网在线高分辨率监测站点的建设以及“3S”技术实现点位到区域的研究,使岩溶碳汇在全球碳循环模型中的重要性更具说服力。     

The State of Arts: Sources,Microbial Processes and Ecological Effects of Iron in the Marine Environment

Iron is the fourth most abundant element in the earth's crust, and it often appears as a trace element in the ocean. Iron has a variable valence and diverse functions, and is an important force to regulate marine primary productivity and drive the geochemical cycle in the ocean. Previous studies have shown that iron plays an important role in maintaining primary productivity, coupling matter cycles, and regulating the transformation of biogenic factors. In recent years, with the development of microbial ecology, iron research has enter more in-depth levels, including microbial-driven iron oxidation-reduction behavior, metabolic processes, and interactions with other major elements(C/N/P). This paper attempts to review the latest progress of iron, focusing on the published literatures of the past fifteen years. Firstly, we explained the sources and occurrence states of iron in the ocean (such as dissolved, colloidal, granular and organic state); Secondly, we reviewed the types and process mechanisms of microbial-mediated iron redoxbehavior (for example nitrate oxidation, and biological reduction, etc.); Finally, we summarized the coupling relationship between iron and C/N/P cycle. Additionally, the ecological roles of iron in specific ecological event (for instance algal bloom) has also been described. Furthermore, the "chemical-biological-physical" theoretical framework for marine iron research is also discussed. The purpose of this paper is to provide more information for marine microecological research and their effects on iron cycle under changing environment, such as global change.     

Effects of Fe and Al incorporations on the bridgmanite–postperovskite coexistence domain

The postperovskite phase transition of Fe and Al-bearing MgSiO₃ bridgmanite, the most aboundant mineral in the Earth's lower mantle, is believed to be a key to understanding seismological observations in the D″ layer, e.g., the discontinuous changes in seismic wave velocities. Experimentally reported phase transition boundaries of Fe and Al-bearing bridgmanite are currently largely controversial and generally suggest wide two-phase coexistence domains. Theoretical simulations ignoring temperature effects cannot evaluate correctly two-phase coexistence domains under high-temperature. We show high-pressure and high-temperature phase transition boundaries for various compositions with geophysically relevant impurities of Fe²⁺SiO₃, Fe³⁺Fe³⁺O₃, Fe³⁺Al³⁺O₃, and Al³⁺Al³⁺O₃ derived from the ab initio finite-temperature free energies calculated combining the internally consistent LSDA + U method and a lattice dynamics approach. We found that at ～ 2500 K, incorporations accompanied by Fe³⁺ expand the two-phase coexistence domains distinctly, implying that D″ seismic discontinuities likely arise from the phase transition of Fe²⁺-bearing bridgmanite.     

High‐Precision Barium Isotope Measurements of Carbonates by MC‐ICP‐MS

This study presents a high‐precision method to measure barium (Ba) isotope compositions of international carbonate reference materials and natural carbonates. Barium was purified using chromatographic columns filled with cation exchange resin (AG50W‐X12, 200–400 mesh). Barium isotopes were measured by MC‐ICP‐MS, using a ¹³⁵Ba–¹³⁶Ba double‐spike to correct mass‐dependent fractionation during purification and instrumental measurement. The precision and accuracy were monitored by measuring Ba isotope compositions of the reference material JCp‐1 (coral) and a synthetic solution obtained by mixing NIST SRM 3104a with other matrix elements. The mean δ^137/134Ba values of JCp‐1 and the synthetic solution relative to NIST SRM 3104a were 0.21 ± 0.03‰ (2s, n = 16) and 0.02 ± 0.03‰ (2s, n = 6), respectively. Replicate measurements of NIST SRM 915b, COQ‐1, natural coral and stalagmite samples gave average δ^137/134Ba values of 0.10 ± 0.04‰ (2s, n = 18), 0.08 ± 0.04‰ (2s, n = 20), 0.27 ± 0.04‰ (2s, n = 16) and 0.04 ± 0.03‰ (2s, n = 20), respectively. Barium mass fractions and Ba isotopes of subsamples drilled from one stalagmite profile were also measured. Although Ba mass fractions varied significantly along the profile, Ba isotope signatures were homogeneous, indicating that Ba isotope compositions of stalagmites could be a potential tool (in addition to Ba mass fractions) to constrain the source of Ba in carbonate rocks and minerals.     

明代(公元1368—1644年)钱塘江河口潮灾时空分布及其影响因素

钱塘江河口是世界著名强潮河口。基于历史文献资料,系统梳理考证了明代(公元1368—1644年)钱塘江河口潮灾记录,分析了潮灾的空间、时间分布特征:(1)北岸潮灾远多于南岸,海门以上河口段与海门以下河口段潮灾次数基本持平,但均少于河口湾段。(2)潮灾在南北两岸的空间分布上,存在转移与变迁,由此导致两岸分别存在明显的平缓期—爆发期—平缓期交替,但平缓期与爆发期的时长并不固定。(3)潮灾强度变化与潮灾频次分布有较强关联,高强度潮灾多发于潮灾频发期。结合历史气候、江道地形等自然环境背景,探讨了影响潮灾时空分布的要素,认为钱塘江潮灾发生的频次及规模大小与流域内干湿变化及历史气温升降有明显关联,而历史极端潮灾则常是多种要素耦合的结果。     

多模式面波非线性反演

利用高频面波反演横波速度一直是浅地表地震工程研究的热点。为深入认识利用高频面波（瑞雷波和勒夫波）评价横波速度的能力,本文首先采取高阶交错网格有限差分法实现两层模型的瑞雷波和勒夫波数值模拟,并应用τ-p变换形成频散能量图。相比瑞雷波,不同模式的勒夫波频散能量很接近,这说明易于实现多模式勒夫波反演。然后利用线性映射实现广义模式识别这种非线性反演方法对含软弱夹层的四层模型的基模式、多模式瑞雷波和勒夫波的变厚度反演。若初始模型很拙劣,相比勒夫波,瑞雷波基模式反演不能重建地层中含有软弱夹层这一特征,瑞雷波多模式反演则可以重建这一特征;勒夫波基模式和多模式反演都可以重建这一特征。即使在地层的泊松比与估计值相差很大时,瑞雷波多模式反演仍能重建地层结构,但其频散曲线总是存在"模式接吻"现象,容易模式误判;而勒夫波反演则不用估计地层泊松比,也不存在"模式接吻"现象。一系列算例表明：高模式瑞雷波的加入会显著提高横波速度评价结果的精度;而高模式勒夫波的加入会令反演系统对半空间以上异常层的参数过于敏感,造成参数过度估计,但也会显著提升对半空间横波速度的评价能力。最后,应用本文方法实现了对实测勒夫波数据的分析。