Evaluating Particle Deposition in the Artificial Groundwater Recharge Process by Physical and CT Imaging Experiments

Particle clogging in the artificial groundwater recharge process is one of the main factors influencing the artificial groundwater recharge efficiency, and particle deposition is the microscopic mechanism of the occurrence and development of particle clogging. Particle deposition in porous media changes the pore structure. The computed tomography (CT) scanning technique is a nondestructive testing method and determines the spatial distribution of pores in porous media. This study combines physical and CT scanning experiments to identify the change process of the pore structure in the artificial groundwater recharge process and compares the pore changes during recharge experiments between two columns containing different media. Porous media changes are observed with the CT scanning technique. The fractal theory is applied in the analysis of CT scan images and physical experiment results. The results of this study indicate that particle deposition can be examined by using CT scan images to obtain pore-related parameters, the internal pore structure of porous media determined through CT scan images can be applied in numerical simulation, and a mathematical model for particle deposition calculation in porous media is established. Compared to the physical experiment measurements, the spatial particle deposition information acquired with the CT scanning technique exhibits a higher accuracy and contains much more relevant data. Not only does this research reveal more clearly the particle clogging mechanism which is based on particle deposition, but also characterize, simulate and predict more accurately the development tendency of particle clogging during artificial groundwater recharge.

     

Topology optimization of free vibrating continuum structures based on the element free Galerkin method

In this paper, the topology optimization design of the free vibrating continuum structures is formulated based on the element free Galerkin (EFG) method. Considering the relative density of nodes as design variable, and the maximization of the fundamental eigenvalue as an objective function, the mathematical formulation of the topology optimization model is developed using the solid isotropic microstructures with penalization (SIMP) interpolation scheme. The topology optimization problem is solved by the optimality criteria method. Finally, the feasibility and efficiency of the proposed method are illustrated with several 2D examples that are widely used in the topology optimization design.     

一种三维刚架—桁架静力分析有限元程序

介绍了三维刚架计算原理以及作者所编制的一种应用于ＰＣ微机的有限元程序．本程序用＂ＦＯＲＴＲＡＮ＂语言编写,采用半动态一维存储．引入了单元整体形函数矩阵,简化了单元非结点载荷与结点载荷的转换过程．可用于计算三维及二维刚架或桁架在多种载荷条件下的位移及杆端内力并可绘出结构的有限元模型、支承、受载及变形状况．通过一系列算例验证了程序的正确性．     

自适应P2P网络搜索算法

提出了一个基于查询代理的无结构P2P网络盲搜索算法，该算法在查询过程中感知并分析P2P网络的相关信息，根据查询满足情况自适应地控制子查询规模。与已有的盲搜索算法相比，查询代理算法实现了更细致的冗余开销控制，并避免了已有算法存在的优化难题。与已有盲搜索算法的对比实验的结果证实该算法可以更有效地降低冗余开销。     

下向分层胶结充填采矿法在招远金矿的应用

本文介绍了在招远金矿灵山五号脉进行下向分层进路回采胶结充填采矿法的试验情况,着重论述了这种采矿方法的适应条件和回采工艺的特点,并对其技术经济指标和经济效益作了初步分析。     

高效液相色谱法测定磺胺二甲嘧啶的有关物质

目的:用高效液相色谱法测定磺胺二甲嘧啶的有关物质。方法:用Alltima C18(5μm,250 mm×4.6 mm)色谱柱;流动相为13.6 g/L磷酸二氢钾缓冲液(用20 g/L氢氧化钾溶液调节pH至4.50)—甲醇的体积比为55∶45;流速1.0 mL/min;检测波长:275 nm;进样体积:20μL。结果:磺胺二甲嘧啶在80~120μg/mL范围内线性关系良好(r=0.9999),磺胺线性范围为0.15~1μg/mL(r=1.0000),磺胺脒线性范围为0.15~1μg/mL(r=1.0000)。结论:该方法简便、准确、专属性好,可用于磺胺二甲嘧啶含量及有关物质检测。     

Understanding the correlation between calcination temperature and performance in low-temperature methanation over Ni-Zr/Al2O3 catalysts

Low-temperature methanation of CO in the continuous stirred tank reactor (CSTR) over Zr doped Ni/Al₂O₃ catalyst calcined at different temperatures (673, 723, and 823 K) was investigated. XRD, TPR, XPS, ICP, SEM, and S-TPR techniques were employed to characterize the fresh and spent catalysts. Based on the characterization results, it was found that low-temperature (673 K) calcination could effectively prohibit the formation of NiAl₂O₄ spinel, thereby resulting in more reducible NiO particles, which were the essential precursor of methanation active sites over the catalyst surface. Thus, the highest CO conversion of 93.6% was achieved over the 25N3ZA-673 catalyst. In addition, the deactivation rate of 25N3ZA-673 was relatively slow in comparison to 25N3ZA-823 due to the presence of more reducible NiO. The formed nickel carbonyl species (Ni[CO]_x), which quickly decomposed at a higher reaction temperature, was closely related to the catalyst deactivation. Therefore, 25N3ZA-673 possessed much better stability at 593 K than that at 553 K.     

水产品中创伤弧菌检测方法建立与应用

目的建立一种水产品中创伤弧菌检测方法 ,并对北京市市售水产品中创伤弧菌污染情况进行监测。方法分别使用18株创伤弧菌菌株和水产品中常污染的背景杂菌,定量接种于检测创伤弧菌的选择性增菌液和4种选择性平板,优化出适合创伤弧菌检测的选择性培养基。采用聚合酶链式反应(PCR)法和增菌培养法分别检测样品中的创伤弧菌后进行方法对比,建立PCR和增菌培养法相结合的检测方法 ,并应用此方法研究北京市市售水产品中创伤弧菌污染状况。结果改良后的选择性增菌液适用于创伤弧菌的检测。北京市市售水产品中创伤弧菌检出率为15.7%(18/115),其中贝类、蟹类、鱼类和虾类样品的检出率分别为23.4%(15/64)、8.3%(1/12)、5.3%(1/19)和5.0%(1/20)。结论 PCR法与传统增菌培养法相结合,可有效提高创伤弧菌检测效率。北京市市售贝类等水产品中创伤弧菌污染率较高,需引起食品安全风险监测重点关注。