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711.
闽江口的盐、淡水混合   总被引:4,自引:1,他引:4       下载免费PDF全文
采用盐、淡水混合比的概念研究闽江口的混合状态,并确定了分层、部分混合、高度混合3种类型的分类指标。研究表明,闽江口主要水道的盐、淡水混合以部分混合为主,其次是分层,高度混合出现的机率较少;盐水异重流发育良好,混合状态的变化与潮流速的变化不相一致;盐水入侵时混合比相对较小,后退时相对较大。闽江口是一个径、潮量比值较小的强潮河口,按照一般规律,其盐、淡水混合应该出现高度混合型,但在闽江口的主汊道中发生  相似文献   
712.
- In this paper, an engineering method is employed to calculate the horizontal and vertical wave forces on the mat of the submersible platform under Froude-Krylov hypothesis. According to some model tests, appropriate diffraction coefficients are selected. And the results of the formulae given in the paper agree satisfactorily with those experimental data now available. The proposed computational method is effective and convenient to use in evaluating the horizontal and vertical wave forces on the mat. An exmaple is also given in this paper. Finally, the effects of the vertical wave force on the platorm's sit-on-bottom stability are analyzed.  相似文献   
713.
荆马河是造成京杭运河徐州段污染的主要纳污、排污河流,河中沉积物约三万吨,沉积深度在0.4米至1.8米之间。本文论述了用柴露草微核技术对沉积物致突变性的研究方法和结果,探讨了对沉积的处理方式。  相似文献   
714.
Some of the most vanadium-rich silicate minerals known are present in green mica schist from the Hemlo gold deposit, Ontario, Canada. Vanadium-rich silicate minerals include green mica (up to 17.6 wt. % V2O3), phlogopite (10.1 wt. % V2O3), pumpellyite (25.7 wt. % V2O3), garnet (18.5 wt. % V2O3), epidote-group minerals (9.1 wt. % V2O3), antimonian vesuvianite (4.3 wt. % V2O3), and titanite (18.5 wt. % V2O5). In addition, minor amounts of V (<2 wt. % V2O3) are present in tourmaline, chlorite, talc and tremolite in other lithologies of the Hemlo deposit. The principal substitution that incorporates V into most of these silicate minerals is Al3+=V3+ in octahedral positions. Vanadium is incorporated into phlogopite mainly by the two substitutions: 3Mg2+ =2V3++ and VIMg2++IVSi4+=VIV3+ +IVAl3+, and all of the three substitutions Ti4++O2- =V3++(OH,F)-, Ti4+=V4+, and 5Ti4+=4V5+ + may have operated in titanite.Vanadium-enriched green mica schist from the Hemlo gold deposit is characterized by uniform Ti/Zr ratios, systematically low Ti, Ni, Co and Sc abundances, and low levels of incompatible elements Th, U, Hf and Zr and is distinct in these respects from its Cr-enriched counterpart. These geochemical features, along with textural evidence (relict quartz and oligoclase phenocrysts), indicate that the V-enriched green mica schist from Hemlo was most likely derived mainly from quartz-oligoclase porphyry. However, its anomalously high V and Cr contents were probably introduced metasomatically from local maficultramafic sources and were fixed in green mica and oxides during the waning of a second regional metamorphism. Vanadium was further remobilized, and its concentration probably enhanced, during the late hydrothermal alteration, which resulted in the formation of the characteristic V-rich calc-silicate minerals.  相似文献   
715.
Abstract

Runoff discharge in the Tuku lowlands, Taiwan, has increased with land development. Frequent floods caused by extreme weather conditions have resulted in considerable economic and social losses in recent years. Currently, numerous infrastructures have been built in the lowland areas that are prone to inundation; the measures and solutions for flood mitigation focus mainly on engineering aspects. Public participation in the development of principles for future flood management has helped both stakeholders and engineers. An integrated drainage–inundation model, combining a drainage flow model with a two-dimensional overland-flow inundation model is used to evaluate the flood management approaches with damage loss estimation. The proposed approaches include increasing drainage capacity, using fishponds as retention ponds, constructing pumping stations, and building flood diversion culverts. To assess the effects on the drainage system of projected increase of rainfall due to climate change, for each approach simulations were performed to obtain potential inundation extent and depth in terms of damage losses. The results demonstrate the importance of assessing the impacts of climate change for implementing appropriate flood management approaches.

Editor Z.W. Kundzewicz

Citation Chang, H.-K., Tan, Y.-C., Lai, J.-S., Pan, T.-Y., Liu, T.-M., and Tung, C.-P., 2013. Improvement of a drainage system for flood management with assessment of the potential effects of climate change. Hydrological Sciences Journal, 58 (8), 1581–1597.  相似文献   
716.
地震观测台站远程测控系统的研制与应用   总被引:1,自引:1,他引:0  
通过远程测控系统,监测无人职守地震观测台站设备的工作状态,室内商业供电状态、室内温湿度的监测,室内安全布防及报警;在区域遥测台网中心发现观测设备出现故障时,可以通过专线网络处理简单的设备故障,应急处理已损坏的辅助设备等。  相似文献   
717.
Soon after the discovery of radio pulsars in 1967, the pulsars are identified as strongly magnetic (typically 1012 G) rapidly rotating (∼102− 0.1 Hz) neutron stars. However, the mechanism of particle acceleration in the pulsar magnetosphere has been a longstanding problem. The central problem is why the rotation power manifests itself in both gamma-ray beams and a highly relativistic wind of electron–positron plasmas, which excites surrounding nebulae observed in X-ray. Here we show with a three-dimensional particle simulation for the global axisymmetric magnetosphere that a steady outflow of electron–positron pairs is formed with associated pair sources, which are the gamma-ray emitting regions within the light cylinder. The magnetic field is assumed to be a dipole, and to be consistent, the pair creation rate is taken to be small, so that the model might be applicable to old pulsars such as Geminga. The pair sources are charge-deficient regions around the null surface, and we identify them as the outer gap. The wind mechanism is the electromagnetic induction which brings about fast azimuthal motion and eventually trans-field drift by radiation drag in the close vicinity of the light cylinder and beyond. The wind causes loss of particles from the system. This maintains charge deficiency in the outer gap and pair creation. The model is thus in a steady state, balancing loss and supply of particles. Our simulation implies how the wind coexists with the gamma-ray emitting regions in the pulsar magnetosphere.  相似文献   
718.
ABSTRACT

Vector-based cellular automata (VCA) models have been applied in land use change simulations at fine scales. However, the neighborhood effects of the driving factors are rarely considered in the exploration of the transition suitability of cells, leading to lower simulation accuracy. This study proposes a convolutional neural network (CNN)-VCA model that adopts the CNN to extract the high-level features of the driving factors within a neighborhood of an irregularly shaped cell and discover the relationships between multiple land use changes and driving factors at the neighborhood level. The proposed model was applied to simulate urban land use changes in Shenzhen, China. Compared with several VCA models using other machine learning methods, the proposed CNN-VCA model obtained the highest simulation accuracy (figure-of-merit = 0.361). The results indicated that the CNN-VCA model can effectively uncover the neighborhood effects of multiple driving factors on the developmental potential of land parcels and obtain more details on the morphological characteristics of land parcels. Moreover, the land use patterns of 2020 and 2025 under an ecological control strategy were simulated to provide decision support for urban planning.  相似文献   
719.
The Kongur Shan Extensional System (KES) is a ~250 km long normal fault system that bounds the Muji–Tashkorgan basin of the Chinese Pamir. It accommodates E–W extension due to the northward indentation of the Pamir salient, and its late Miocene activity has been the focus of tectonic studies. While the KES has a main normal component, ~WNW–ESE‐striking segments have an additional right‐lateral strike‐slip component. Here, we quantify late Quaternary horizontal and vertical slip rates at three locations along the KES, where active faults cut and offset abandoned geomorphic features. We find rates of >3–4 mm a?1 (horizontal) along the western Muji fault in the north and of ~1.7 mm a?1 (vertical) and ~1 mm a?1 (horizontal) along the Kongur Shan fault in the south during the late Pleistocene. These rates are consistent with GPS and late Miocene rates, and imply that E–W extension in the Muji–Tashkorgan basin is faster in the north than in the south.  相似文献   
720.
潘北斗 《地质与勘探》2022,58(3):532-544
在具有较多已知矿床(点)的区域,从矿床(点)的空间分布模式中可以挖掘出成矿过程的重要信息,这些信息对于认识区域成矿规律、指导区域找矿具有重要意义。不同矿床类型之间的空间关联,通常都是通过结合地质和成矿规律定性分析来研究,缺少定量、精确的研究方法。针对这个问题,本文提出了一种定量分析不同矿床(点)类型之间空间关联的方法—基于ROC曲线的矿床空间关系挖掘方法。该方法采用数据分析中常用的ROC曲线,通过构建矿床空间点缓冲区,利用GIS软件计算得到ROC曲线和曲线下面积AUC以及Youden指数等相关参数,利用ROC曲线和AUC等参数定量探讨不同矿床类型之间的空间关联。通过网络分析对不同矿床类型之间的空间关系定量指标进行可视化,通过社团检测算法找出众多不同矿床类型中存在较强关联关系的矿床类型群组。以中南半岛矿床点的空间分布为实例进行研究,挖掘出了该研究区9种主要矿床类型之间的空间关联规律。结果表明,研究区的热液型Pb矿、热液型Cu矿、热液型Pb-Zn矿、砂矿型Au矿四种主要矿床类型之间存在较强空间关联(AUC值0.74~0.88),在空间上相互靠近,相伴产出。热液型Sn矿、砂矿型Sn两类之间关联关系强烈(AUC值0.62~0.79)。热液型Au矿、热液型Fe矿、热液型Sb矿的空间分布模式较为独立,与其他矿床类型之间关联较弱。利用本文提出的方法可以定量挖掘出区域上不同矿床类型之间的空间关联关系,为区域成矿研究和找矿实践提供重要信息。  相似文献   
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