利用盐湖常见元素的助烧结作用绿色制备氧化镁及磷酸镁水泥          下载免费PDF全文

李颖  董金美  肖学英  郑卫新  文静  常成功 《盐湖研究》2020,28(2):15-25

低活性氧化镁是制备磷酸镁水泥(MPC)的关键原材料。现行低活性氧化镁的生产方式导致了制备MPC具有能耗高和成本高的缺点,不利于其推广应用。利用盐湖中常见元素如B,Na、K和Cl的助烧结作用,在≤1 200℃煅烧盐湖提锂镁渣、外掺B的轻烧镁粉和水氯镁石的热解产物制备低活性氧化镁。介绍了低活性氧化镁的粒径、比表面积、孔隙率、化学组成、矿物组成和形貌等物理特征,以及低活性氧化镁制备MPC的凝结时间、水化产物、微观结构、抗压强度、体积稳定性等凝结硬化性能,并分析了烧结温度对低活性氧化镁的理化性能及MPC的凝结硬化性能的影响。相比现有技术,利用盐湖共存元素的助烧结作用可将氧化镁的烧结温度由1 500～1 800℃降低到1 200℃以下,有利于实现低活性氧化镁及MPC的低能耗、低成本绿色制备,促进MPC的推广应用。  相似文献   

A note on the lake level variations of Nam Co,south-central Tibetan Plateau from 2005 to 2019     

ShiQiao Zhou 《寒旱区科学》2020,12(6):430-435

Tibetan lake levels are sensitive to global change, and their variations have a large impact on the environment, local agriculture and animal husbandry practices. While many remote sensing data of Tibetan lake level changes have been reported, few are from in-situ measurements. This note presents the first in-situ lake level time series of the central Tibetan Plateau. Since 2005, daily lake level observations have been performed at Lake Nam Co, one of the largest on the Tibetan Plateau. The interannual lake level variations show an overall increasing trend from 2006 to 2014, a rapid decrease from 2014 to 2017, and a surge from 2017 to 2018. The annual average lake level of the hydrological year (May-April) rose 66 cm from 2006 to 2014, dropped 59 cm from 2014 to 2017, and increased 20 cm from 2017 to 2018, resulting in a net rise of 27 cm or an average rate of about 2 cm per year. Compared to the annual average lake level based on the calendar year, it is better to use the annual average lake level based on the hydrological year to determine the interannual lake level changes. As the lake level was stable in May, it is appropriate to compare May lake levels when examining interannual lake level changes with fewer data. Overall, remote sensing results agree well with the in-situ lake level observations; however, some significant deviations exist. In the comparable 2006-2009 period, the calendar-year average lake level observed in-situ rose by 10-11 cm per year, which is lower than the ICESat result of 18 cm per year.  相似文献   

2011年日本东北大地震（M_W=9.0）震间与震前变形场特征及其对强震预测的启示          下载免费PDF全文

朱守彪 《地球物理学报》2020,63(2):427-439

强震震前(preseismic)动力学过程的研究对于地震预测具有十分重要的意义,但由于观测资料的限制,目前对强震前孕震区力学状态及其演化过程的认识还非常有限.2011年日本东北9.0特大地震(Tohoku-Oki)发生在GPS观测台站最为密集的地区,为研究特大地震震间(interseismic)与震前的变形状态提供了难得的机会.文中将利用日本东北大地震之前连续的GPS观测资料,分别计算震间与震前的速度场与变形场.通过对比分析发现,日本东北地区(Tohoku)震前的应变状态与震间的有很大的不同,震间的变形主要受到太平洋板块向日本海沟北西西向的俯冲挤压作用所控制,其主压应变以近东西向压缩为主,日本东北地区的运动方向与太平洋板块的运动方向大体一致.但是,临近地震前(震前)日本东北地区的运动方向发生了很大变化,震前30天的连续GPS观测结果显示,速度场的优势方向经常变换,间歇性地出现与太平洋板块运动方向相反的情况.这意味着震前孕震区的力学状态发生了很大的改变.这种变化可能与震前破裂成核或慢滑移及慢地震等过程有关,这些过程将加速或促进大地震的发生,从而为大地震的发生准备了力学条件.值得特别强调的是,这些现象都是可以通过直接观测能够发现的大地震之前的异常现象.由此可见,加密GPS站点进行连续观测,寻找震前变形异常区以及探索异常的物理机制对于地震预测预报有重要的科学意义.  相似文献   

Northward cooling of the Kuncha nappe and downward heating of the Lesser Himalayan autochthon distributed to the south of Mt. Annapurna,western central Nepal     

Toru Nakajima  Harutaka Sakai  Hideki Iwano  Tohru Danhara  Takafumi Hirata 《Island Arc》2020,29(1)

We investigated the tectonothermal history of the Lesser Himalayan sediments (LHS), which are tectonically overlain by the Higher Himalayan Crystalline. Fission‐track dating and the track length measurement of detrital zircons obtained from the Kuncha nappe and the Lesser Himalayan autochthonous sediments in western central Nepal revealed northward cooling of the nappe and possible downward heating of the autochthon by the overlying hot nappe. Nine zircon fission‐track (ZFT) ages of the nappe showed northward‐younging linear distribution from 11.6 Ma in the front at Tamghas, 6 Ma in the central at Naudanda, and 1.6 Ma in the northernmost point at Tatopani. Thermochronological invert calculation of the ZFT length elucidated that the Kuncha nappe gradually cooled down (30 °C/Myr) at the front and rapidly cooled down (120 °C/Myr) at the root zone. In contrast, the ZFT age of the Chappani Formation, located just beneath the Kuncha nappe in the central part, demonstrated a totally reset age of 6.8 Ma, whereas the Virkot Formation, structurally far from the nappe, yielded a partially reset age of 457.3 Ma. This suggests that the LHS underwent downward heating, resulting in a thermal print on the upper part of the LHS; however, the thermal effect was not sufficient to anneal ZFT totally in the deeper part. Presently, the nappe cover is eroded and denuded from this area. Detrital zircons from the Chappani Formation in Tansen area to the south of the Bari Gad Fault did not show any evidence of annealing, suggesting that nappe never covered the LHS distributed to the south of the fault.  相似文献   

2020年1月19日伽师MS6.4地震灾害损失评估及震害特点分析     

阿里木江·亚力昆  谭明  姚远  张文秀 《内陆地震》2020,34(1):30-39

2020年1月19日新疆伽师发生M S6.4地震,造成1人死亡、2人受伤,各类建(构)筑物、公共服务设施、生命线工程等都遭受不同程度的破坏。按照国家相关标准的原则和方法,通过对本次地震现场震害调查,评估出本次地震造成的总直接经济损失为15.26亿元,灾后恢复重建经费约需20.78亿元,并且分析了本次地震震害特点。这为今后的抗震救灾和灾后重建提供了科学依据。  相似文献   

典型草原露天煤矿区地下水-湖泊系统演化   总被引：1，自引：0，他引：1  

夏蔓宏  董少刚  刘白薇  李铱  李政葵  王超  周雨泽 《湖泊科学》2020,32(1):187-197

由于气候干旱、大量疏排地下水导致草原露天煤矿区普遍存在着水文循环失调、土壤沙化、草地退化等环境地质问题.本研究以呼伦贝尔草原伊敏露天煤矿为研究对象,在对矿区地下水湖泊系统调查分析的基础上,结合水文、气象及遥感影像等数据,应用水均衡原理构建矿区地下水位湖泊面积响应机制的数学模型,并利用此模型预测分析矿区开发对伊敏盆地内湖泊面积的影响.结果表明:煤矿开采35年来,伊敏盆地湖群数量由开采前(1982年)的5个变为如今(2017年)的2个,湖泊总面积由原来的6.94 km 2萎缩到1.12 km 2;矿区地下水湖泊关系由自然状态下的地下水补给湖泊型向湖泊补给地下水型演化;本文建立的地下水湖泊耦合数学模型可较好地对湖泊面积进行预测,在气候因素波动不大、矿山开发稳定的状况下,该矿闭矿时(2045年)研究区湖泊面积将萎缩至0.56 km^2.  相似文献   

不同海域沉积物对尿素吸附的实验模拟研究     

薛峤娜  胡博  谭丽菊  王江涛 《海洋学报》2018,40(10):190-199

本文对采自渤海、黄海和东海3个典型海域的沉积物进行了尿素吸附/解吸的实验室模拟研究，用Freundlich吸附模型和Henry吸附模型分析了不同沉积物对尿素吸附的热力学特性，并研究了温度、沉积物粒径、有机质含量等因素对尿素在沉积物表面吸附的影响。结果表明，沉积物对尿素的吸附/解吸过程总体呈现3个阶段:快速吸附阶段（0~5 h）—慢速吸附阶段（5~12 h）—平衡阶段（12 h之后）。当水体中的尿素浓度较低时，沉积物解吸释放尿素，随着上覆水中尿素浓度逐渐增加，沉积物对上覆水中的尿素产生吸附行为，各海区沉积物对尿素的吸附能力由强至弱依次为渤海、东海、黄海，这可能与沉积物的类型有关。Freundlich方程和Henry方程均可模拟沉积物对尿素的吸附，温度、粒径以及沉积物中有机质含量等因素均对尿素在沉积物上的吸附产生影响，随着温度升高，尿素在沉积物上的吸附量变小，沉积物粒径越小，有机质含量越高，吸附尿素的能力越强，因此，揭示尿素在沉积物表面的环境行为时，必须考虑以上因素的影响。  相似文献   

四川省城市地震灾害脆弱性综合评价研究   总被引：1，自引：1，他引：0  

李琳  王俊杰 《震灾防御技术》2018,13(4):968-977

城市化进程的不断推进使得城市的地震灾害脆弱性日益加剧，而城市承灾体的脆弱性受复杂因素影响。本文针对评价指标受主观性影响较大的问题，基于人口、工程、经济及社会4个方面，构建了城市震害综合脆弱性评价指标体系；并构建基于实码加速遗传算法优化投影寻踪（RAGA-PP）的城市震害脆弱性评价模型；最后，对四川省21个市、州进行了震害脆弱性评价。结果表明:巴中、南充等地脆弱性较高，成都、攀枝花等地脆弱性较低；经济因素对城市震害脆弱性影响较大；该评价模型能够克服人为主观性，有效可行。  相似文献   

海底底质声学原位测量电路控制系统研究     

吕斌  祁国梁  李官保  王景强  刘杰 《海洋科学》2018,42(5):32-39

介绍了一种液压驱动贯入式海底沉积声学原位测量系统的电路控制单元的研究实现过程,以及该控制单元在南海北部海底沉积声学调查中的应用。该电路控制单元以Cortex-A8处理器为核心,集成大容量FLASH存储器,与单片机接口控制板进行串口通讯,实现对声学发射采集单元和机械液压贯入单元的可视化控制和监测。基于该电路控制单元,海底底质声学原位测量系统兼具自容式和在线式两种工作模式,可自容记录或实时采集声学原位测量单元在海底的工作状态数据、海底沉积物声速和声衰减系数等声学特性数据。该声学原位测量系统的实验室联调及南海海试结果表明,使用该电路控制单元对海底底质声学测量过程的监测与控制是有效的,对精确获取海底底质的原位声学特性有重要作用,可以促进海底底质声学原位测量系统的产品化。  相似文献   

Assessment of erosion and settling properties of fine sediments stored in cobble bed rivers: the Arc and Isère alpine rivers before and after reservoir flushing          下载免费PDF全文

C. Legout  I.G. Droppo  J. Coutaz  C. Bel  M. Jodeau 《地球表面变化过程与地形》2018,43(6):1295-1309

Cohesive sediment dynamics in mountainous rivers is poorly understood even though these rivers are the main providers of fine particles to the oceans. Complex interactions exist between the coarse matrix of cobble bed rivers and fine sediments. Given that fine sediment load in such environments can be very high due to intense natural rainfall or snowmelt events and to man‐induced reservoir or dam flushing, a better understanding of the deposition and sedimentation processes is needed in order to reduce ecohydrological downstream impacts. We tested a field‐based approach on the Arc and Isère alpine rivers combining measurements of erosion and settling properties of river bed deposits before and after a dam flushing, with the U‐GEMS (Gust Erosion Microcosm System) and SCAF (System Characterizing Aggregates and Flocs), respectively. These measurements highlight that critical shears, rates of erosion, settling velocities and propensity of particles to flocculate are highly variable in time and space. This is reflective of the heterogeneity of the hydrodynamic conditions during particle settling, local bed roughness, and nature and size of particles. Generally the deposits were found to be stable relative to what is measured in lowland rivers. It was, however, not possible to make a conclusive assessment of the extent to which the dynamics of deposits after reservoir flushing were different from those settled after natural events. The absence of any relationships between erosion and deposition variables, making it impossible to predict one from another, underlined the need to measure all of them to have a full assessment of the fine sediment dynamics and to obtain representative input variables for numerical models. While the SCAF was found to be effective, an alternative to the U‐GEMS device will have to be found for the erodibility assessment in cobble bed rivers, in order to make more rapid measurements at higher shears. Copyright © 2017 John Wiley & Sons, Ltd.  相似文献