基于拉格朗日插值法修正地形影响的分布式降水模型研究

降水量一直是进行水文分析计算的输入项，对其分布状况的模拟直接影响水文分析成果精度。降水中心位置及其中心降水量对暴雨分析尤为重要，而目前尚未见对降水中心位置方面的模型研究。在对目前国内外降水模型分析的基础上，根据天气系统降水如不受地形影响其降水量等值线在平面上的分布近似为一组同心椭圆这一原理，建立了一种能够模拟次降水过程的降水中心位置及其中心降水量的新型分布式降水数学模型，并对其进行地形影响因素修正。由于模型建立原理简单，易于实现对流域未设站研究点的实时降水量估计，同时由于模型能够指明降水中心位置及其中心降水量，因此在流域暴雨分析和洪水预报中具有实用价值。模型经实践检验具有较高精度。     

鄂 北 地 区 钻 头 优 选 探 讨

为适应鄂尔多斯塔巴庙区块勘探开发需要，利用区域测井资料进行钻头选型，并结合现场实践优化钻头类型和钻井参数，提高钻井效率。通过新型PDC钻头推广应用,单口井所需钻头数量减少3~4只，减少起下钻3回次以上，缩短钻井周期3~5天。     

Metrics to assess how longitudinal channel network connectivity and in‐stream Atlantic salmon habitats are impacted by hydropower regulation

Habitat fragmentation in channel networks and riverine ecosystems is increasing globally due to the construction of barriers and river regulation. The resulting divergence from the natural state poses a threat to ecosystem integrity. Consequently, a trade‐off is required between the conservation of biodiversity in channel networks and socio‐economic factors including power generation, potable water supplies, fisheries, and tourism. Many of Scotland's rivers are regulated for hydropower generation but also support populations of Atlantic salmon (Salmo salar L.) that have high economic and conservation value. This paper investigates the use of connectivity metrics and weightings to assess the impact of river barriers (impoundments) associated with hydropower regulation on natural longitudinal channel connectivity for Atlantic salmon. We applied 2 different weighting approaches in the connectivity models that accounted for spatial variability in habitat quality for spawning and fry production and contrasted these models with a more traditional approach using wetted area. Assessments of habitat loss using the habitat quality weighted models contrasted with those using the less biologically relevant wetted area. This highlights the importance of including relevant ecological and hydrogeomorphic information in assessing regulation impacts on natural channel connectivity. Specifically, we highlight scenarios where losing a smaller area of productive habitat can have a larger impact on Atlantic salmon than losing a greater area of less suitable habitat. It is recommended that future channel connectivity assessments should attempt to include biologically relevant weightings, rather than relying on simpler metrics like wetted area which can produce misleading assessments of barrier impacts.     

Modelling spatial variations in dissolved oxygen in fine‐grained streams under uncertainty

This paper presents a novel triple‐layer model, called VART DO‐3L, for simulation of spatial variations in dissolved oxygen (DO) in fine‐grained streams, characterized by a fluid mud (fluff or flocculent) layer (an advection‐dominated storage zone) as the interface between overlying stream water and relatively consolidated streambed sediment (a diffusion‐dominated storage zone). A global sensitivity analysis is conducted to investigate the sensitivity of VART DO‐3L model input parameters. Results of the sensitivity analysis indicate that the most sensitive parameter is the relative size of the advection‐dominated storage zones (A_s/A), followed by a lumped reaction term (R) for the flocculent layer, biological reaction rate (μ_o) in diffusive layer and biochemical oxygen demand concentration (L) in water column. In order to address uncertainty in model input parameters, Monte Carlo simulations are performed to sample parameter values and to produce various parameter combinations or cases. The VART DO‐3L model is applied to the Lower Amite River in Louisiana, USA, to simulate vertical and longitudinal variations in DO under the cases. In terms of longitudinal variation, the DO level decreases from 7.9 mg l at the Denham Springs station to about 2.89 mg l^?1 at the Port Vincent station. In terms of vertical variation, the DO level drops rapidly from the overlying water column to the advection‐dominated storage zone and further to the diffusive layer. The DO level (C_F) in the advective layer (flocculent layer) can reach as high as 40% of DO concentration (C) in the water column. The VART DO‐3L model may be applied to similar rivers for simulation of spatial variations in DO level. Copyright © 2014 John Wiley & Sons, Ltd.     

Dynamic response of a pile considering the interaction of pile variable cross section with the surrounding layered soil

Assuming that the pile variable cross section interacts with the surrounding soil in the same way as the pile toe does with the bearing stratus, the interaction of pile variable cross section with the surrounding soil is represented by a Voigt model, which consists of a spring and a damper connected in parallel, and the spring constant and damper coefficient are derived. Thus, a more rigid pile–soil interaction model is proposed. The surrounding soil layers are modeled as axisymmetric continuum in which its vertical displacements are taken into account and the pile is assumed to be a Rayleigh–Love rod with material damping. Allowing for soil properties and pile defects, the pile–soil system is divided into several layers. By means of Laplace transform, the governing equations of soil layers are solved in frequency domain, and a new relationship linking the impedance functions at the variable‐section interface between the adjacent pile segments is derived using a Heaviside step function, which is called amended impedance function transfer method. On this basis, the impedance function at pile top is derived by amended impedance function transfer method proposed in this paper. Then, the velocity response at pile top can be obtained by means of inverse Fourier transform and convolution theorem. The effects of pile–soil system parameters are studied, and some conclusions are proposed. Then, an engineering example is given to confirm the rationality of the solution proposed in this paper. Copyright © 2017 John Wiley & Sons, Ltd.     

Effect of bed surface roughness on longitudinal dispersion in artificial open channels

In several empirical and modelling studies on river hydraulics, dispersion was negatively correlated to surface roughness. In this study, it was aimed to investigate the influence of surface roughness on longitudinal dispersion under controlled conditions. In artificial flow channels with a length of 104 m, tracer experiments with variations in channel bed material were performed. By use of measured tracer breakthrough curves, average flow velocity, mean longitudinal dispersion, and mean longitudinal dispersivity were calculated. Longitudinal dispersion coefficients ranged from 0·018 m² s^?1 in channels with smooth bed surface up to 0·209 m² s^?1 in channels with coarse gravel as bed material. Longitudinal dispersion was linearly related to mean flow velocity. Accordingly, longitudinal dispersivities ranged between 0·152 ± 0·017 m in channels with smooth bed surface and 0·584 ± 0·015 m in identical channels with a coarse gravel substrate. Grain size and surface roughness of the channel bed were found to correlate positively to longitudinal dispersion. This finding contradicts several existing relations between surface roughness and dispersion. Future studies should include further variation in surface roughness to derive a better‐founded empirical equation forecasting longitudinal dispersion from surface roughness. Copyright © 2011 John Wiley & Sons, Ltd.     

伊犁盆地南缘中新生代构造样式与铀成矿关系

伊犁盆地是我国最早发现砂岩型铀矿的地区,近十几年来一直保持砂岩型铀矿找矿的不断突破,盆地南缘自西向东查明了一系列砂岩型铀矿床,这些铀矿床的分布与盆地南缘构造关系密切。本文总结了伊犁盆地南缘构造样式类型,分析了不同构造样式下氧化流体补给、运移规律,并结合铀矿体的空间分布,指出构造样式差异是造成砂岩型铀矿体空间分布的关键因素;从氧化流体补给窗的开启、流体的汇聚和还原性气体聚集的控制等方面讨论了构造样式对铀矿体空间定位的机制,指出单斜稳定地层中纵弯背斜是控制铀空间分布的主要构造,要注意不同构造样式约束下成矿区域的稳定型和地下水补给的多样性,在此基础上讨论了伊犁盆地南缘铀矿的找矿方向及主要矿物类型。     

横向振动格栅紊流紊动特性试验

建立了一套大尺度格栅紊流试验系统,格栅进行有别于传统垂向模式的横向振动,采用粒子图像测速技术(Particle Image Velocimetry,PIV)测量流速。对瞬时流速的检验表明,该系统产生的紊流场具有较强的随机性和统计规律性。均方根流速在格栅片附近变化较大,在两片格栅中间处趋于稳定,纵向均方根流速明显大于垂向均方根流速,二者比值在1.5~2.0之间,接近天然明渠紊流。雷诺应力在距格栅越近处波动越大,随着距格栅距离的增加而减小,至两片格栅中间处雷诺应力基本为0。时间和长度积分尺度在格栅片处最小,随着距格栅距离的增加而线性增加,至两片格栅中间处达到最大值。流速能谱呈现Kolmogorov理论的-5/3次方规律。本系统生成的紊流场的统计规律与传统的垂向振动格栅紊流较为一致,但纵向和垂向的紊动强度更接近实际,为后续紊流中泥沙和污染物等运动机理的研究奠定了基础。     

基于稳定同位素的东太平洋大青鲨(Prionace glauca)营养级研究

碳、氮稳定同位素为分析淡水和海洋生态系统的生物营养关系提供了有力手段,但在大洋鱼类中的应用还很少。本研究以热带东太平洋大青鲨(Prionace glauca)整节脊椎骨作为样品(叉长范围153—242cm),运用稳定同位素技术,分析大青鲨的δ~(13)C值和δ~(15)N值及其变化,比较不同基线生物的选择对营养级计算的影响。结果表明,大青鲨δ~(13)C范围为–15.76‰—–13.41‰,最大差值2.35‰;δ~(15)N范围为10.62‰—17.72‰,最大差值7.1‰;δ~(13)C值和δ~(15)N值随个体长度的变化不明显(可能原因是样品鱼均为较大个体),性别间的差异不显著,但不同基线生物的选择对营养级计算值的影响较大。本文研究表明,通过整节脊椎骨的稳定同位素测定来获得大青鲨的摄食特征信息是可行的。由于基线生物对营养级计算的影响问题难以在短期内解决,今后可将相对营养级或营养级的变化作为重点,研究人类活动(如捕捞)对大洋鱼类摄食和营养级的影响。