A numerical study of the motion of a wave running up a beach

The main difficulty for the numerical calculation of the wave running up a beach is the treatment of its moving water boundary. In this paper a scheme of turning the free boundary problem into a fixed boundary problem is designed. The calculated run-up height is consistent with the experiments. Some interesting wave phenomena are also found.     

三峡库区大石板滑坡区排水系统效果评估

结合三峡库区大石板滑坡工程实例 ,以连续 36天的降雨过程为条件 ,利用已有的地下水位观测资料 ,采用人工神经网络方法预测滑坡内地下水位在排水工程实施前后的变化 ,以此作为非饱和—饱和—非衡定地下渗流计算的特定水头边界。根据计算的地下水位进行滑坡稳定性分析 ,结合稳定分析成果对排水系统工程的效果进行评价。结果表明 ,地下排水工程的实施可较大幅度地提高滑坡的稳定性。     

Frequency and development of slugs in a horizontal pipe at large liquid flows

The generation of slugs was studied for air–water flow in horizontal 0.0763 m and 0.095 m pipes. The emphasis was on high liquid rates (u_LS ? 0.5 m/s) for which slugs are formed close to the entry and the time intervals between slugs are stochastic. A “fully developed” slug flow is defined as consisting of slugs with different sizes interspersed in a stratified flow with a height slightly larger than the height, h₀, needed for a slug to be stable. Properties of this “fully developed” pattern are discussed. A correlation for the frequency of slugging is suggested, which describes our data as well as the data from other laboratories for a wide range of conditions. The possibility is explored that there is a further increase of slug length beyond the “fully developed” condition because slugs slowly overtake one another.     

Flow patterns and heat transfer in vertical upward air–water flow with surfactant

Flow patterns, the pressure drag reduction and the heat transfer in a vertical upward air–water flow with the surfactant having negligible environmental impact were studied experimentally in a tube of 2.5 cm in diameter. Visual observations showed that gas bubbles in the air–water solution with surfactant are smaller in size but much larger in number than in pure air–water mixture, at the all flow regimes. The transition lines in the flow regime map for the solution of air–water mixture with surfactant of the 300 ppm concentration are mainly consistent with the experimental data obtained in clear air–water mixture. An additive of surfactant to two-phase flow reduces the total pressure drop and decrease heat transfer, especially in the churn flow regime.     

Steady ground-water flow through layered media

This paper deals with the flow through a layered medium that has alternate sand and clay strata. The solutions of plane, axisymmetric and spatial cases are given. Research results in this paper can be applied to seepage calculations and hydraulic engineering designs in flood areas and reclaimed marsh land.List of Symbols A _n Upward leakage factor of the nth sand stratum - A _n Downward leakage factor of the nth sand stratum - [B] Matrix of eigenvector - B _nm Element of [B] corresponding to the nth sand stratum and the mth eigenvalue - C _m , C _N+m Arbitrary constants belonging to the terms contained the mth eigenvalue - C_mj Arbitrary constant belonging to the term contained the mth eigenvalue due to a line source in the jth sand stratum - [D] Inverse matrix of [B] - d _f0 ^sup+ Additional length of the seepage path for ditches in symmetric flow - F, ^F _m Area and dimensionless area corresponding to the mth eigenvalue ( ^F _m = _fm ^sup2 F) - f ₀ Coefficient of additional resistance of partially penetrating well - H Total water head; upstream water head - h, h _n Water head and water head of the nth sand stratum - h _nj Water head of the nth sand stratum due to a line source in the jth sand stratum - h ₀ Surface water head - h/H × 100% Potential - i, j Number - k, k Permeability coefficient of the sand stratum and clay stratum, respectively - k _n , k _n Permeability coefficient of the nth sand stratum and the nth clay stratum, respectively - L Length - m Number - N Total number of sand or clay strata - n Number - Q _j Discharge of a line source distributed along a vertical line in the jth sand stratum - Q _ji The partial discharge of the ith well (or line source), which flows through the screen pipe penetrating the jth sand stratum - qj Discharge of a face source distributed on an area - unit breadth multiplied by the thickness of the jth sand stratum. The abbreviation is: unit discharge of a face source in the jth sand stratum - qji Unit discharge of a face source on the ith surface element in the jth sand stratum - R Constant radius - S Distance; length of a curve - ^S _m Dimensionless length of a curve corresponding to the mth eigenvalue ( ^S _m = _m S) - s Number - T _n , T _n Thickness of the nth sand stratum and the nth clay stratum, respectively - t Number; thickness - x, y, z Cartesian coordinates - y Polar coordinate; radius; distance - ^y _m Dimensionless distance corresponding to the mth eigenvalue ( ^y _m = _m y) - y ₀ Radius of well - y ₀ Radius of equivalent completely penetrating well - Infinitesimal half breadth - Infinitesimal area - Angle - Eigenvalue     

(SrTiO_3)_(1-x)(SrTaO_2N)_x固溶体的制备及光催化性能研究(英文)

通过高温固相反应合成了N掺杂的SrTiO3和(SrTiO3)1-x(SrTaO2N)x固溶体,对其进行了X射线衍射,紫外可见吸收光谱,X射线光电子能谱分析和比表面积的表征。随x由0增大至0.4,固溶体带隙变窄,由3.2eV降至2.3eV,吸收光谱由紫外光区扩展到可见光区。在甲醇溶液(50mLCH3OH+220mLH2O)中进行了光催化分解水产生氢气的反应,在硝酸银溶液(270mL,0.01mol·L-1)中进行了光催化分解水产生氧气的反应,在可见光(λ420nm)照射下,实现了可见光响应的光催化分解水。     

Cocos nucifera L. water as green corrosion inhibitor for acid corrosion of aluminium in HCl solution

<正>The ability of Cocos nucifera L.water(CW) as non-toxic corrosion inhibitor for acid corrosion of aluminium in 0.5 mol/L HCl has been studied using chemical technique.CW shows significant inhibition as corrosion inhibitor,with 93%efficiency at the highest concentration of the inhibitor.The inhibitive action is attributed to the adsorption of the inhibitor molecules on metal surface following Langmuir adsorption isotherm.     

Water transfer characteristics in the vertical direction during methane hydrate formation and dissociation processes inside non-saturated media

In order to study water transfer characteristics inside non-saturated media during methane hydrate formation and dissociation processes, water changes on the top, middle and bottom locations of experimental media during the reaction processes were continuously followed with a novel apparatus with three pF-meter sensors. Coarse sand, fine sand and loess were chosen as experimental media. It was experimentally observed that methane hydrate was easier formed inside coarse sand and fine sand than inside loess. Methane hydrate formation configuration and water transfer characteristics during methane hydrate formation processes were very different among the different non-saturated media, which were important for understanding methane hydrate formation and dissociation mechanism inside sediments in nature.     

固相萃取-超高压液相色谱-串联质谱测定水中19种抗生素

应用固相萃取(SPE)及液相色谱-串联质谱(LC-MS/MS)技术,建立了水中痕量(ng/L)四环素类、磺胺类、大环内酯类、喹诺酮类和β-内酰胺类5类共19种抗生素的同时定量检测方法。水样通过HLB萃取小柱富集后,以C18反相色谱柱为分析柱,乙腈-0.1%甲酸溶液为流动相,采用LC-MS/MS进行定量分析。选择电喷雾正电离源(ESI+),多反应监测模式(MRM),内标法定量。19种抗生素在0.5~1 000μg/L范围内均具有良好的线性关系,方法的定量下限(S/N=10,1 000倍浓缩)为0.1~0.5 ng/L。以纯水和河水(黄浦江水)作为基底,13C-咖啡因为内标物,加标质量浓度为20、100 ng/L时,抗生素的平均加标回收率分别为75%~125%和77%~132%,相对标准偏差(RSD)分别为1.7%~6.9%和0.9%~6.5%,表明所建立的测试方法准确可靠。研究结果表明,黄浦江水受到了抗生素污染,共检出15种抗生素,检出的四环素类、磺胺类、大环内酯类、喹诺酮类及β-内酰胺类抗生素污染质量浓度分别为13.0~56.9、12.2~103.4、53.8~84.8、3.1~26.2、16.5~181.6 ng/L。     

雎水流域的水化学特征及其地表水与地下水的相互转化

为了解特定流域的水化学特征及其运移和转化的历史,为水资源科学管理提供依据,分析了小流域雎水河的水化学特征。结果表明:(1)雎水河流域主要是大气降水补给的地矿化度的溶滤水。(2)雎水河全线都是地下水补给地表水。(3)部分泉点矿化度相对较高与SO24-较高有关,可能是因为流经了含煤地层。