电容去离子化去除地下水中镉的影响因素

以高比表面积活性炭作为吸附剂制备电容电极,研究电容去离子化（CDI）对地下水中镉的吸附性能。分别探讨了镉初始质量浓度、体系供电电压、地下水中常见阳离子种类对CDI去除镉的影响。结果表明,CDI吸附镉符合准二级吸附动力学、满足Langmuir等温吸附方程,CDI对镉的吸附为单分子层吸附。吸附量随镉初始质量浓度的升高而增加;在低质量浓度时,较高的供电电压会提高初始阶段的吸附速率,但对电极的最终吸附量无显著影响;地下水中主要阳离子的存在增加了体系的电导率,从而促进了CDI对镉的吸附,提高了镉的吸附速率和去除率。     

新疆和田普阳煤矿开采技术条件分析

和田属南疆严重缺煤地区,布雅煤矿区是和田地区的主要煤产地。普阳煤矿含煤地层为侏罗系下统康苏组和侏罗系中统杨叶组。井田水文地质类型属孔隙、裂隙类简单型;工程地质类型属层状岩类复杂型;环境地质质量中等。     

Thermo-mechanical performance of layered transversely isotropic media around a cylindrical/tubular heat source

We develop a new numerical model based on a precise integration method to investigate the coupled thermo-mechanical performance of layered transversely isotropic media around a cylindrical/tubular heat source. To obtain the relational matrices of the extended precise integration method, we first convert the governing equations of the problem into ordinary differential matrix equations through the Laplace–Hankel transform. Then, the cylindrical heat source is divided into a series of plane heat sources, and the plane temperature load term is added to the state vector between layer elements. By combining the layer elements, we build a layered transversely isotropic numerical model containing a cylindrical heat source in the transformed domain. Finally, we solve the model in the transformed domain and obtain the solution of the problem in the real domain through the Laplace–Hankel transform inversion. The accuracy of this method is verified by comparing the solutions with the results of the analytical method and the finite element method. Then, we study the influence of the anisotropy of thermal parameters, the embedded depth, the length/radius ratio, the type of heat source and the stratification of the medium on the thermo-mechanical coupled performance.

     

Micromechanism of the diffusion of cement-based grouts in porous media under two hydraulic operating conditions: constant flow rate and constant pressure

Acta Geotechnica - Cement-based grout has been widely used in various civil engineering applications. The diffusion of cement-based grouts in porous media is an important issue in soil sealing and...     

用辐射传输方程改进算法反演LandSAT8海表温度的效果检验和适用条件分析

为检验辐射传输方程改进算法推广用于反演LandSAT8 海表温度(SST)的可行性及适用条件,本研究在修订算法部分参数的基础上,分别反演出算法改进前后的LandSAT8 SST并进行比较。MODIS SST验证表明改进算法对大气透过率偏差和SST偏差均有明显改善,除2019-08-21图像外,其他3景图像SST偏差在0.5℃左右;浮标SST验证表明改进算法在近岸海域对SST偏差改善效果同样显著,其平均偏差bias和均方根误差rmse分别减少到0.14、0.18℃,基本可以忽略不计;进一步研究发现,改进算法SST反演精度与研究海域大气透过率分布均匀程度呈显著的正相关关系,R²[bias(SST)]=0.920 7,R²[rmse(SST)]=0.934 0。使用改进算法遥感监测电厂温排水：嵩屿电厂表层海水温升羽流不明显;而后石电厂表层温升现象最显著,温升幅度和扩散影响范围最大,在其排水口附近存在稳定的高温水体(温升＞3℃);晋江电厂表层温升羽流呈扇形分布,流轴短,主要集中在排水口附近。     

Dynamic responses of unsaturated half‐space soil to a moving harmonic rectangular load

The problem of the dynamic responses of a semi‐infinite unsaturated poroelastic medium subjected to a moving rectangular load is investigated analytical/numerically. The dynamic governing equations are obtained with consideration of the compressibility of solid grain and pore fluid, inertial coupling, and viscous drag as well as capillary pressure in the unsaturated soil, and they can be easily degraded to the complete Biot's theory. Using the Fourier transform, the general solution for the equations is derived in the transformed domain, and then a corresponding boundary value problem is formulated. By introducing fast Fourier transform algorithm, the unsaturated soil vertical displacements, effective stresses, and pore pressures induced by moving load are computed, and some of the calculated results are compared with those for the degenerated solution of saturated soils and confirmed. The influences of the saturation, the load speed, and excitation frequency on the response of the unsaturated half‐space soil are investigated. The numerical results reveal that the effects of these parameters on the dynamic response of the unsaturated soil are significant.     

Energy flux partitioning and evapotranspiration in a sub‐alpine spruce forest ecosystem

In this study, we examined the year 2011 characteristics of energy flux partitioning and evapotranspiration of a sub‐alpine spruce forest underlain by permafrost on the Qinghai–Tibet Plateau (QPT). Energy balance closure on a half‐hourly basis was H + λE = 0.81 × (R_n ? G ? S) + 3.48 (W m^?2) (r² = 0.83, n = 14938), where H, λE, R_n, G and S are the sensible heat, latent heat, net radiation, soil heat and air‐column heat storage fluxes, respectively. Maximum H was higher than maximum λE, and H dominated the energy budget at midday during the whole year, even in summer time. However, the rainfall events significantly affected energy flux partitioning and evapotranspiration. The mean value of evaporative fraction (Λ = λE/(λE + H)) during the growth period on zero precipitation days and non‐zero precipitation days was 0.40 and 0.61, respectively. The mean daily evapotranspiration of this sub‐alpine forest during summer time was 2.56 mm day^?1. The annual evapotranspiration and sublimation was 417 ± 8 mm year^?1, which was very similar to the annual precipitation of 428 mm. Sublimation accounted for 7.1% (30 ± 2 mm year^?1) of annual evapotranspiration and sublimation, indicating that the sublimation is not negligible in the annual water balance in sub‐alpine forests on the QPT. The low values of the Priestley–Taylor coefficient (α) and the very low value of the decoupling coefficient (Ω) during most of the growing season suggested low soil water content and conservative water loss in this sub‐alpine forest. Copyright © 2013 John Wiley & Sons, Ltd.     

“一带一路”成员国居民健康状况的时空统计分析

健康是影响不同国家和地区发展的关键因素,全面了解“一带一路”成员国的居民健康状况,是探讨“一带一路”成员国之间健康医疗合作的重要基础。本文选择了4个代表性的健康状况指标（出生期望寿命、总生育率、过早非传染性疾病死亡率和结核病发病率）,利用Moran's I指数、Getis-Ord G指数对“一带一路”135个成员国的健康状况进行时空统计,分析了健康状况的空间相关性和空间分布模式,研究了健康状况的时空格局。研究发现：① 2000—2016年“一带一路”大部分成员国的各项健康状况指标均朝着改善和优化方向发展;健康状况指标均呈现显著的正空间自相关性;② 总体而言,在“一带一路”成员国中,欧洲国家的居民健康状况最好;南北美洲和大洋洲国家的居民健康状况良好;亚洲国家的居民健康状况总体良好,但东南亚部分国家的结核病发病率较高;非洲国家的居民健康状况虽有明显改善,但仍处于较低状态。因此,“一带一路”成员国应进一步加强健康医疗合作,共同推动健康丝绸之路的发展。     

Impact of fractional probability distributions on statistics of hydraulic conductivity,dynamics of groundwater flow and solute transport at a low-permeability site

The fractional Brownian motion (fBm) and fractional Lévy motion (fLm) can easily describe the geometry and the statistical structure of hydraulic conductivity (K) for real-world. However, the fBm and fLm models have not been systematically evaluated when building the K field for a low-permeability site. In this study, both the fBm and fLm are used to simulate the low-K field at NingCheGu (NCG), Tianjin, China. Groundwater flow and solute transport are then computed using MODFLOW and MT3DMS, respectively, and the influence of the fBm/fLm models for K on groundwater flow and solute transport is discussed. Results show that the fLm fits better the statistics of the low-K medium than fBm, and the random logarithmic K (LnK) field generated by fLm is more stable because the resultant LnK field captures more of the measured properties at the field site than that generated by fBm. In contrast, the LnK generated by fBm is more likely to form both high-K channels and low-K barriers. The fBm therefore predicts more extreme behaviours in flow and transport, including the preferential flow, low-concentration blocks and solute retention. The overall groundwater renewal period and solute travel time for the fLm simulation are slightly shorter than those for fBm. The impacts of the fLm and fBm models on the statistics of the resultant LnK fields and the dynamics of groundwater flow and solute transport revealed by this study shed light on the selection and evaluation of the fractional probability distribution models in capturing the K fields for low-K media.