Morphological and sedimentary impacts and recovery on a mixed sandy to pebbly seabed exposed to marine aggregate extraction (Eastern English Channel,France)     

Sophie Le Bot  Robert Lafite  Matthieu Fournier  Agnès Baltzer  Michel Desprez 《Estuarine, Coastal and Shelf Science》2010

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GRACE时变信号恢复方法对比分析     

刘冰石  邹贤才 《大地测量与地球动力学》2019,39(2):204-209

针对利用GRACE重力数据反演地表质量变化过程中产生的时变信号削弱和泄露现象,分别采用尺度因子法和迭代恢复法对信号进行恢复,并选用CSR Mascon产品从时间序列变化和空间分布两个角度对两种恢复方法的效果进行对比分析。结果表明:1)尺度因子法虽实现上较为简单,但其计算结果完全依赖于所选的先验模型,当所选模型的可靠性较差时,会影响到GRACE反演结果的可靠性。2)迭代恢复法的恢复过程仅受GRACE原始观测值的约束,能较好地恢复研究区域的长期趋势信号和周期信号,但在部分区域可能存在信号过量恢复的现象。建议采用迭代恢复法进行GRACE时变信号恢复。  相似文献   

低轨卫星初始状态误差对反演地球重力场的影响     

张兴福  沈云中 《测绘科学》2009,34(3)

基于动力学法反演地球重力场的基本理论,研究了卫星初始状态向量误差对应用低轨卫星精密轨道数据反演地球重力场的影响。在仅考虑低轨卫星初始状态误差的情况下进行了模拟计算,结果表明:在利用低轨卫星精密轨道数据反演地球重力场时,卫星初始状态向量误差需要重新进行估计;在目前的轨道精度水平下,若不顾及误差方程二次项的影响,反演弧长不宜过长;卫星初始状态速度误差(约1.5mm/s)的影响要大于位置误差(约10 cm)的影响。  相似文献   

The role of eddies in solute transport and recovery in rock fractures: Implication for groundwater remediation          下载免费PDF全文

Seung Hyun Lee  In Wook Yeo  Kang‐Kun Lee  Won Sang Lee 《水文研究》2017,31(20):3580-3587

A better understanding of solute transport and retention mechanism in rock fractures has been challenging due to difficulty in their direct observations in microscale rough‐walled fractures. Six representative troughs in a rough‐walled fracture were selected for microscale observations of eddy formation with increasing flow velocity and its effect on spatiotemporal changes of solute concentration. This experimental study was enabled by a microscale visualization technique of micro particle image velocimetry. With increasing flow velocity (Re ≤ 2.86), no eddies were generated, and solutes along the main streamlines transported rapidly, whereas those near the wall moved slowly. A larger amount of solutes remained trapped at all troughs at Re = 2.86 than Re < 1. For Re = 8.57, weak eddies started to be developed at the troughs on the lee side, which little contributed to overall solute flushing in the fracture. Accordingly, a large of amount of water was needed for solute flushing. The flow condition of 1 < Re < 10, before a full development of eddies, was least favourable in terms of time and amount of remediation fluid required to reach a target concentration. After large eddies were fully developed at troughs on the lee side for Re = 17.13, solutes were substantially reduced by eddies with less amount of water. Fully developed eddies were found to enhance solute transport and recovery, as opposed to a general consensus that eddies trap and delay solutes. Direct inflow into troughs on the stoss side also made a great contribution to solute flushing out of the troughs. This study indicates that fully developed eddies or strong inflows at troughs are highly possible to form for Re > 10 and this flow range could be favourable for efficient remediation.  相似文献   

聚四氟乙烯平板型气态膜回收淡盐水中氯气          下载免费PDF全文

于伯杉 《盐湖研究》1993,1(4):75-79

本文以离子膜电解氯化钾制取碳酸钾工艺产生的淡盐水为原料,系统地研究了聚四氟乙烯平板型气态膜回收氯过程中膜性能和次氯酸钠水溶液的制备。初步研究表明,次氯酸钠含量大于100g/L,氢氧化钠有效利用率为90％;聚四氟乙烯膜有传质快、对离子截留性能好、使用寿命长等优点,在工业上有较好的应用前景。  相似文献   

Valency Study of Vanadium in Stone Coal Ash of Jiangxi Province     

Xu Guozhen Ge Naie Li Jigui 《中国地质大学学报(英文版)》1990,(1)

Vanadium-bearing stone coal is a new vanadium resource;recovery ofV_2O_5 from the coal has been investigated.It has been found that a satisfactoryextraction of V_2O_5 depends on both the oxidation of V and its reaction with so-dium salt.V in the coal ash of Yushan mainly exists in two oxidation states:98％V(Ⅲ)and2％V(Ⅳ).The distribution of valency of V shows that organicmatter determines V valency at low temperatures,at about470℃,V(Ⅲ)iscompletely oxidized to V(Ⅳ);above500℃,the temperature is the most impor-tant factor for the oxidation of V .At higher temperatures no more V is oxidizedto V(Ⅴ);an equilibrium is established after92％of V is oxidized to V(Ⅴ).The roles of NaCl in the recovery of V_2O_5 from the coal ash were discussed.The best conditions for roasting are temperature750-800℃for1 h.underthe oxidation-chlorination atmosphere.When the ore:NaCl=100:10 by weight,η_roast reaches85.5％.According to the results,a flowsheet for V_2O_5 extrac-tion from coal ash has been proposed.  相似文献   

珠江三角洲宏观经济发展与震后恢复方案     

黄昭庆  黄贯虹 《华南地震》1995,15(3):75-86

在投入产出综合平衡模型的基础上，在充分考虑珠江三角洲地区资源的条件下，结合该区未来经济发展的战略目标，建立了宏观经济发展的动态递推模型。利用该模型，借助系统优化算法，对珠江三角洲地区宏观经济的发展作出了最优规划，对该区未来的震害提出了最佳的恢复方案。由震害所致间接经济损失的系统分析，是结合原发展规划方案的对投资结构、产业结构作出的动态分析，可作为未来珠江三角洲地区产业的调整、投资、方向的改变，以主  相似文献   

Geomorphological study on a clastic accretionary prism: The Nankai Trough     

Kyoko  Okino Yukihiro  Kato 《Island Arc》1995,4(3):182-198

Abstract The Nankai Trough, off southwest Japan, is one of the best sites for the study of geomorphic characteristics of a clastic accretionary prism. A recent multibeam survey over the central and eastern parts of the Nankai accretionary prism has revealed a large variation of the topography along the trough axis. Analysis of the bathymetric data suggests the existence of prism deformational features of different scales, such as depressions, embayment structures and cusps. These structures are the results of slope instability caused by basement relief of subducted oceanic plate. Unstable slopes recover by new accretion and development of a low angle thrust. Small-scale deformation due to the subduction of a small isolated seamount is then adjusted to the regional trend. By contrast, a 30 km indentation of the wedge observed in the eastern part of the Nankai Trough, the Tenryu Cusp, has seemed to retain its geometry. The subducted Philippine Sea plate has deformed greatly near the eastern end of the Nankai Trough, because of the collision between the Izu-Ogasawara (Bonin) arc and central Japan. Therefore, the indentation may be the result of the continuous subduction of a basement high, such as the Zenisu Ridge, which has been formed under north-south compression due to the arc-arc collision.  相似文献   

频谱成像技术在稠油热采地震监测中的应用   总被引：2，自引：0，他引：2  

王新红 《华北地震科学》2005,23(3):1-8

频谱成像技术可有效的描述地质反射层厚度的非连续性和岩性的非均质性,其在理论上主要是依据薄层反射的调谐原理,过去通常采用以离散傅里叶变换为基础的算法,但是,该方法存在着明显的局限性,因为估算的地震振幅谱的重要特征是所选时窗长度的函数.如果所选时窗过短,振幅谱会与变换窗函数褶积,失去频率的局部化特征,而且过短的时窗会使子波的旁瓣呈现为单一反射的假象.增加时窗长度,会改善频率的分辨率.但如果所选时窗过长,时窗内的多个反射会使振幅谱以槽痕为特征,很难分清单个反射的振幅谱特征.由于在实际运用中,以傅里叶变换相关的算法的时窗问题,难以选择好时窗长度,而且无法定量分析时窗长度产生的偏差,因而会使振幅谱的估算产生偏差.以小波变换为基础的时频分析技术成了非平稳性信号的重要分析工具,在很多实际应用中已取代了傅里叶变换的分析方法.以小波变换为基础的瞬时谱分析技术能得到精确的时频分析结果,同时避免了时窗问题.它反映出了储层在纵向上时间及厚度上变化情况和横向上的地质不连续性的信息,因此能使解释人员快速而有效地描述储层特征的空间变化.  相似文献   

The geomorphological significance of airflow patterns in transverse dune interdunes   总被引：1，自引：0，他引：1  

M.C. Baddock  I. Livingstone  G.F.S. Wiggs   《Geomorphology》2007,87(4):322-336

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