不同煤层掘进工作面瞬变电磁法探测应用研究

煤矿井下瞬变电磁法成为煤矿井下超前探测工作的重要手段，在矿井水害预测预报上发挥着很大的作用。随着矿井上组煤层资源的逐渐枯竭，煤矿开采资源逐渐延伸向下组煤层。同一井田范围内同煤层及其顶底板的岩性特征一般相差不大，瞬变电磁法在同煤层施工过程中接收到的物理背景场较为接近；而不同煤层及其顶底板岩性特征通常会有较大的差别，瞬变电磁法在不同煤层施工过程中会接收到差别较大的物理背景场。当矿井存在多煤层开采时，通过大量数据研究瞬变电磁法在不同煤层巷道探测中的响应特征规律，分析并掌握不同煤层条件对瞬变电磁法探测结果的影响，能够提高瞬变电磁法在多煤层探测成果的准确性。     

综采工作面活性磁化水防尘技术研究

煤矿生产是环境较为封闭的井下作业，具有一定的特殊性，作业空间湿度高、生产环境复杂，其中粉尘是危害最大的因素之一，会对机器和人体造成不同程度的损害。粉尘的危害主要由两方面决定:煤尘能够燃烧，在浓度较高时还会爆炸；粉尘会危害人的身体健康。以平煤股份十矿-320 m水平己四采区东翼下段的己_15-16-24130工作面为研究对象，研究磁化水除尘的方法及原理，通过对比分析优选出活性磁化水添加剂，在该工作面试验后具有良好的除尘效果，大大增加了可见度、降低了空气中悬浮的煤尘。研究对该矿井其他工作面除尘工作具有指导意义。     

纳米Co/rGO磁性复合吸附材料的制备及对Cu2+的吸附性能

以改进Hummer法制备的薄片状氧化石墨烯(GO)为载体和模板负载钴离子，然后采用原位还原法制得纳米金属Co/石墨烯磁性复合吸附材料(Co/rGO)，并将其应用于对Cu2+的吸附和脱除，以期为高效可复用的铜离子脱除剂的合成与应用提供指导。实验结果证实，Co/rGO复合材料具有超顺磁性，能够很方便的使用磁铁进行分离并在无磁场情况下振荡分散。Co/rGO复合材料对Cu2+具有稳定的吸附/脱附性能，实验条件下对Cu2+的最大吸附容量达到117.5 mg/g且5 min内实现吸附平衡，远优于其原料GO的60 min吸附容量27.6 mg/g。本工作系统考察了NaOH加入量、络合剂种类、溶剂种类等关键因素对Co粒子在rGO载体上形貌和分布特性的影响，比较了不同合成条件下的复合材料对Cu2+吸附效果的影响，并对优选条件下制备的Co/rGO复合材料进行了FT-IR, XRD, SEM表征。研究结果表明，纳米Co/rGO磁性材料对Cu2+的吸附过程更符合Freundlich模型，属于多层吸附。室温下吸附焓ΔH=17.81 kJ/mol，吸附反应平衡常数Kθ=3.65。当初始Cu2+浓度为39.22 mg/L时，对Cu2+的吸附率为93.47%，五次吸附/脱附循环后吸附容量仍保持在初始值的94%，每次吸附后溶液中残余Cu2+浓度均满足钴电解液对杂质铜离子的浓度去除要求(5 mg/L)或GB 8978-1996污水综合排放标准3级(2 mg/L)，有望在相关领域发挥作用。     

Investigation on the effectiveness of the repair method 8.3 “Corrosion protection by increasing the electrical resistivity” in chloride-containing concrete Part 2: Chloride redistribution in concrete after application of a system sealing surface protective coating

This DFG-funded research project aimed to gain a better understanding of the mechanisms of the W-Cl repair principle within the framework of fundamental investigations, to contribute to the creation of the necessary basis for a broader application of the repair principle in practice. The focus was on the development of a model to describe the chloride redistribution after the application of a system sealing surface protective coating. On the basis of Fick's second law of diffusion, a mathematical model with a self-contained analytical solution was developed, with the help of which the chloride redistribution after application of a system sealing surface protective coating can be calculated under the idealized assumption of complete water saturation of the concrete. Furthermore, the influence of the dehydration of the concrete, expected as a result of the application of the repair principle W-Cl, on the chloride redistribution was investigated. On the basis of laboratory tests and numerical simulations, material-specific reduction functions were developed to quantify the relationship between the chloride diffusion coefficient and the ambient humidity.     

小型特种精细化工过程自动化和信息化研究发展趋势探讨

针对采取小批量间歇性批次生产方式、工艺介质腐蚀性强、危险性大的小型特种精细化工生产工艺研究试验过程自动化、信息化程度不高，导致工艺研究试验中获取数据较少、过程机理研究不够透彻、人工操作多、安全风险高、研究试验消耗大及效率不高等问题，综述了期待通过智能控制、在线分析、模拟仿真和虚拟制造、工况监测及预测性维护以及信息管理和生产调度等关键技术的研究和应用，提高小型特种精细化工生产工艺过程的自动化和信息化程度，实现小型特种精细化工生产工艺过程的数字化、虚拟化和智能化，降低生产安全风险和试验消耗，提高小型特种精细化工生产工艺研究试验的成功率和效率，达到小型特种精细化工生产工艺过程的数字化设计和精准生产的目标。     

基于双应力加速寿命试验的关节轴承寿命预测与可靠性分析

自润滑关节轴承寿命主要是由衬垫的磨损性能决定的,但衬垫的磨损一般是非线性的,使得寿命难以预测。采用同时改变载荷和摆频2种应力的方法进行加速寿命试验,建立以pv值、磨损量退化数据为输入参数,寿命值为输出参数的灰色神经网络预测模型。经验证该预测模型对关节轴承寿命预测的最大误差仅为7.33%,平均误差仅为3.892%。对不同加速应力下自润滑关节轴承可靠性进行评估,结果表明,关节轴承的可靠性在L_(10)(可靠度为90%时的寿命)之前下降趋势缓慢,然后迅速下降,pv值越大可靠性下降越迅速;随着pv值的增大,关节轴承寿命近似呈指数下降,经验证可用逆幂率加速模型反映二者关系。     

Machining accuracy improvement for a dual-spindle ultra-precision drum roll lathe based on geometric error analysis and calibration

This paper performs a comprehensive analysis and calibration on the geometric error of the ultra-precision drum roll lathe with dual-spindle symmetrical structure and cross slider layout. Firstly, the volumetric error model which contains all geometric errors of the dual-spindle ultra-precision drum roll lathe (DSUPDRL) is developed based on the combination of the homogenous transfer matrix (HTM) and multi-body system (MBS) theory. Secondly, sensitivity analysis for the volumetric error model is conducted to identify the sensitive geometric error components of the DSUPDRL using an improved Sobol method based on the quasi-Monte Carlo algorithm. The result of sensitivity analysis laid the foundation for the subsequent geometric error calibration. Then, some sensitive error components along the X and Z directions are calibrated using a laser interferometer and a pair of inductance displacement probes. Besides the volumetric error model, the concentricity error caused by dual-spindle symmetrical structure is proposed and calibrated by the on-machine measurement using a classic reversal method. Finally, a large-scale roller mold with a diameter of 250 mm and a length of 600 mm is machined using the DSUPDRL after calibration. The experimental result shows that 1.4 μm/600 mm generatrix accuracy is obtained, which validate the effectiveness of the geometric error analysis and calibration.     

多泥沙河流水电站水轮机转轮内部流动数值模拟

针对多泥沙水电站水轮机转轮的泥沙磨损问题,以HLA351-LJ-275水轮机为模型,对水轮机在设计工况下,运用N-S方程和标准κ-ε湍流模型,利用CFX求解器进行仿真流动模拟。水轮机转轮进口沿叶高20%、50%、80%流面的压力、泥沙速度及泥沙体积分数分布的数值结果表明,水轮机转轮叶片工作面压力大于背面且最小压力高于气化压力。泥沙速度在叶片进水边和出水口位置普遍较高。水轮机转轮叶片工作面的泥沙体积分数大于背面,叶片工作面的泥沙体积分数在叶片出水口普遍较高,叶片背面的泥沙体积分数在叶片进水边普遍较高。研究结果对多泥沙河流水轮机转轮叶片的泥沙磨损评估及维修具有指导意义。     

Numerical study of hydrodynamic flow of a Casson nanomaterial past an inclined sheet under porous medium

The main aim of the current paper is to investigate the mass and heat transportation of a Casson nanomaterial generated by the inclination of the surface. The magnetic field effect along with suction or injection are considered. The working nanomaterial is taken into consideration based on the concept of the Buongiorno nanofluid theory, which explores the thermal efficiencies of liquid flows under movement of Brownian and thermophoretic phenomena. The emergent system of differential expressions is converted to dimensionless form with the help of the appropriate transformations. This system is numerically executed by the implementation of Keller–Box and Newton's schemes. A good agreement of results can be found with the previous data in a limiting approach. The behavior of the physical quantities under concern, including energy exchange, Sherwood number, and wall shear stress are portrayed through graphs and in tabular form. The Nusselt number and Sherwood number are found to diminish against the altered magnitudes of Brownian motion and the inclination parameter. Moreover, the velocity profile decreases with the growth of the inclination effect. In the same vein, the buoyancy force and solutal buoyancy effects show a direct relation with the velocity field. The outcomes have promising technological uses in liquid‐based systems related to stretchable constituents.     

Influence of particle contact models on soil response of poorly graded sand during cavity expansion in discrete element simulation

The discrete element method (DEM) has been extensively adopted to investigate many complex geotechnical related problems due to its capability to incorporate the discontinuous nature of granular materials. In particular, when simulating large deformations or distortion of soil (e.g. cavity expansion), DEM can be very effective as other numerical solutions may experience convergence problems. Cavity expansion theory has widespread applications in geotechnical engineering, particularly to the problems concerning in situ testing, pile installation and so forth. In addition, the behaviour of geomaterials in a macro-level is utterly determined by microscopic properties, highlighting the importance of contact models. Despite the fact that there are numerous contact models proposed to mimic the realistic behaviour of granular materials, there are lack of studies on the effects of these contact models on the soil response. Hence, in this study, a series of three-dimensional numerical simulations with different contact constitutive models was conducted to simulate the response of sandy soils during cylindrical cavity expansion. In this numerical investigation, three contact models, i.e. linear contact model, rolling resistance contact model, and Hertz contact model, are considered. It should be noted that the former two models are linear based models, providing linearly elastic and frictional plasticity behaviours, whereas the latter one consists of nonlinear formulation based on an approximation of the theory of Mindlin and Deresiewicz. To examine the effects of these contact models, several cylindrical cavities were created and expanded gradually from an initial radius of 0.055 m to a final radius of 0.1 m. The numerical predictions confirm that the calibrated contact models produced similar results regarding the variations of cavity pressure, radial stress, deviatoric stress, volumetric strain, as well as the soil radial displacement. However, the linear contact model may result in inaccurate predictions when highly angular soil particles are involved. In addition, considering the excessive soil displacement induced by the pile installation (i.e. cavity expansion), a minimum distance of 11a (a is the cavity radius) is recommend for practicing engineers to avoid the potential damages to the existing piles and adjacent structures.