川南沐川地区宣威组底部铌-稀土多金属富集层富集规律、沉积环境与成矿模式

云南、贵州地区对晚二叠世宣威组底部Nb-REE多金属富集层的研究取得了重要进展,但其成因还有较大争议.为厘清沐川地区宣威组底部Nb-REE多金属富集层成因机制及富集规律,本研究开展了野外实地调查、矿物学、岩相古地理与岩石地球化学等系统性研究,探讨其物源、富集规律,建立了成矿模式.结果 表明,川南沐川地区宣威组底部Nb-...     

2021年2月13日日本本州东海岸MW7.2地震矩心矩张量解

根据美国地质调查局(United States Geological Survey,缩写为USGS)国家地震信息中心(National Earthquake Information Centre,缩写为NEIC)的测定,2021 年2 月13 日14 时7 分50 秒( UTC) ,日本本州以东发生了一次矩震级高达 M...     

Control strategies and experimental verifications of the electromagnetic mass damper system for structural vibration control

The electromagnetic mass damper （EMD） control system, as an innovative active control system to reduce structural vibration, offers many advantages over traditional active mass driver/damper （AMD） control systems. In this paper, studies of several EMD control strategies and bench-scale shaking table tests of a two-story model structure are described. First, two structural models corresponding to uncontrolled and Zeroed cases are developed, and parameters of these models are validated through sinusoidal sweep tests to provide a basis for establishing an accurate mathematical model for further studies. Then, a simplified control strategy for the EMD system based on the pole assignment control algorithm is proposed. Moreover, ideal pole locations are derived and validated through a series of shaking table tests. Finally, three benchmark earthquake ground motions and sinusoidal sweep waves are imposed onto the structure to investigate the effectiveness and feasibility of using this type of innovative active control system for structural vibration control. In addition, the robustness of the EMD system is examined. The test results show that the EMD system is an effective and robust system for the control of structural vibrations.     

生物土壤结皮铁代谢微生物组成及其功能基因对演替的响应

采用微生物宏基因组学微阵列GeoChip 5.0技术,选择腾格里沙漠东南缘沙坡头地区不同年代人工固沙植被区的生物土壤结皮（BSC）为对象,分析BSC演替过程中参与铁代谢的功能微生物组成及其功能基因变化特征,研究微生物铁代谢对BSC演替的响应及调控。结果表明：真菌参与铁吸收和转运过程,古菌参与铁转运和贮存过程,细菌则在铁代谢吸收、转运和贮存过程中均起主要调控作用。门水平上,BSC铁代谢功能微生物组成变化对演替的响应不敏感,BSC铁代谢微生物主要为变形菌门（Proteobacteria）。BSC铁代谢功能基因多样性的显著提高和三类铁代谢过程基因信号强度达到最高水平需要经过61 a的演替。调控BSC铁吸收过程的主要功能基因为亚铁氧化酶编码基因iro;调控原核生物铁转运过程的主要功能基因,为羟基苯甲酰丝氨酸铁外膜转运体编码基因cirA和Fe（Ⅱ）转运蛋白编码基因feoB,真菌铁转运过程主要依靠含铁细胞转运体和铁氧化酶高亲和力的作用;调控铁贮存过程的主要功能基因为固定相类核蛋白编码基因dps。在BSC演替阶段末期,上述铁代谢功能基因强度的显著增加促进了微生物的铁代谢潜能。干旱、半干旱荒漠生态系统植被恢复过程中微生物铁代谢潜能的恢复需要较长时间。     

地震前电磁辐射信息特征研究

反映电磁辐射信息的地震前异常变化很多,但都有一个震前平静－加强－平静然后发震的特征,为了更好地体现这种特征,根据十几年来河北廊坊电磁台网的观测资料,通过给不同强度段的各台日信息量赋予不同的权值,并把当日各台权值累加来反映当日内多台信息量集中的强弱,然后把上述权累加和用一种不连续积分的方法反映异常的持续时间,通过对监测范围内４次Ｍｓ≥５．０地震震例分析,发现该方法反映震前异常特征明显,短临效果很好,     

金刚石与深部碳循环

深部碳循环是全球碳循环研究中不可或缺的部分。较之表层碳,人类对地球深部碳储库的储量、碳的迁移方式和交换量都缺乏清晰认识。作为来自地球深部的碳单质矿物,金刚石是研究深部碳循环的绝佳样品。近年来原位微区分析技术的突飞猛进为研究金刚石及深部碳循环提供了良好条件。文中对表层与深部碳交换、深部碳储库及金刚石矿物学性质进行了介绍,并通过金刚石及其包裹体的稳定同位素组成,探讨了金刚石的形成机制及含碳流体/熔体的性质与来源问题。     

估算地表热通量和近地层土壤含水量的变分方法

提出一种反演地表感热通量、潜热通量和近地层土壤含水量的变分方法,该方法把不同高度上的风速、位温以及湿度梯度的观测资料与Monin-Obukhov相似理论计算值的偏差、土壤水分蒸发参数化方案估算的蒸发潜热与由相似理论导出值的偏差在地表能量平衡的约束下融合到一个目标泛函数中,采用最优化算法寻求问题的解.利用2001年6月中国暴雨试验与研究项目在安徽肥西观测资料进行了数值验证,结果表明该方法估算的通量值与Bowen比法具有很好的相关性且又能克服当Bowen比等于-1时计算通量出现的不稳定;同时能克服用廓线法求解热通量与地表能量平衡条件有较大出入的缺点.对观测误差的敏感性试验也表明变分方法是3类方法中最稳定的.反演的近地层土壤含水量对降水具有很好的响应并与观测的0-15 cm深度上平均土壤湿度的变化趋势具有很好的一致性,其绝对偏差小于0.03 m3/m3.     

辽宁海洋综合经济区划分的初步探讨

我国是海洋大国，有相当陆域国土面积三分之一的海洋国土。随着海洋资源的开发利用，海洋经济不断发展，海洋经济区逐渐形成。在全国划分经济区时，不应忽视海洋经济区。沿海省区在划分经济区时，更应把海洋列入到省级经济区内。辽宁是我国沿海省区之一，通过对辽宁海洋经济区划分的研究，探讨海洋经济区及其划分的有关理论、实践与方法。     

核地球物理和化探综合测量在上海市区工程地质调查中的应用

本文介绍在上海市区断裂构造调查中 ,核地球物理测量和化探的应用效果。应用α卡、地面伽马能谱U、Th、K和总量 (Σ)及壤中气汞等测量方法 ,采用组合指标推断断裂构造 ,推断出的断裂构造与地震推断的结果相比较 ,具有较好的一致性。这些方法经济、快速、有效 ,有着广泛的应用前景     

Variability in the vertical hyporheic water exchange affected by hydraulic conductivity and river morphology at a natural confluent meander bend

River confluences and their associated tributaries are key morphodynamic nodes that play important roles in controlling hydraulic geometry and hyporheic water exchange in fluvial networks. However, the existing knowledge regarding hyporheic water exchange associated with river confluence morphology is relatively scarce. On January 14 and 15, 2016, the general hydraulic and morphological characteristics of the confluent meander bend (CMB) between the Juehe River and the Haohe River in the southern region of Xi'an City, Shaanxi Province, China, were investigated. The patterns and magnitudes of vertical hyporheic water exchange (VHWE) were estimated based on a one‐dimensional heat steady‐state model, whereas the sediment vertical hydraulic conductivity (K_v) was calculated via in situ permeameter tests. The results demonstrated that 6 hydrodynamic zones and their extensions were observed at the CMB during the test period. These zones were likely controlled by the obtuse junction angle and low momentum flux ratio, influencing the sediment grain size distribution of the CMB. The VHWE patterns at the test site during the test period mostly showed upwelling flow dominated by regional groundwater discharging into the river. The occurrence of longitudinal downwelling and upwelling patterns along the meander bend at the CMB was likely subjected to the comprehensive influences of the local sinuosity of the meander bend and regional groundwater discharge and finally formed regional and local flow paths. Additionally, in dominated upwelling areas, the change in VHWE magnitudes was nearly consistent with that in K_v values, and higher values of both variables generally occurred in erosional zones near the thalweg paths of the CMB, which were mostly made up of sand and gravel. This was potentially caused by the erosional and depositional processes subjected to confluence morphology. Furthermore, lower K_v values observed in downwelling areas at the CMB were attributed to sediment clogging caused by local downwelling flow. The confluence morphology and sediment K_v are thus likely the driving factors that cause local variations in the VHWE of fluvial systems.