阿克达拉可吸入颗粒物本底浓度变化特征

通过阿克达拉区域大气本底站2007年全年监测发现,以北疆经济区为背景区域的大气中PMIO的年平均本底浓度为10.08Ug/m3.可吸入颗粒物的本底浓度采暖期是非采暖期的两倍左右.可吸入颗粒物本底浓度季节变化特征明显,月平均本底浓度最高为12月,次高为3月.PMIO本底浓度的日变化不规则但基本呈上升趋势,PM1.0和PM2.5的本底浓度日变化呈双峰双谷特征,本底浓度1d内的最高值和次高值出现的时间段与城市相关研究结果相反.     

Micromechanical parameters in bonded particle method for modelling of brittle material failure

Bonded particle modelling (BPM) is nowadays being extensively used for simulating brittle material failure. In BPM, material is modelled as a dense assemblage of particles (grains) connected together by contacts (cement). This sort of modelling seriously depends on the mechanical properties of particle and contact, which are named here as micro‐parameters. However, a definite calibration methodology to obtain micro‐parameters has not been so far established; and many have reported some serious problems. In this research, a calibration procedure to find a unique set of micro‐parameters is established. To attain this purpose, discrete element code of UDEC is used to perform BPM. This code can be conveniently developed by the user. The proposed BPM is composed of rigid polygonal particles interacting at their contact points. These contacts can undergo a certain amount of tension, and their shear resistance is provided by cohesion and friction angle. The results demonstrate that each material macro‐property (i.e. Young's modulus, Poisson's ratio, internal friction angel, internal cohesion, and tensile strength) is directly originated from and distinctly related to the contact properties (i.e. normal and shear stiffness, friction angel, cohesion, and tensile strength). Copyright © 2010 John Wiley & Sons, Ltd.     

白水煤矿煤矸石基本性能研究与分析

通过对白水煤矿煤矸石进行外观分类、化学组成、矿物成分分析和X衍射分析将其分为5种不同外型的煤矸石,其中,第Ⅲ类矸石属于高岭石质矸石黏土岩类矸石,其矿物相主要包括石英、高岭石、伊利石和少量的黄铁矿。实验研究不同类别矸石的粒径范围、陈化时间等对原材料塑性的影响表明:降低原料最大粒径,可以提高塑性,当粒径从-1.0 mm降低到-0.1 mm时,Ⅰ类矸石塑性指数IP提高了6.9;Ⅱ类矸石的IP提高了10.8;Ⅲ类矸石的IP提高了5.6;延长陈化时间,可以提高煤矸石的塑性,当陈化时间3 d时,陈化时间对塑性的贡献明显,当陈化时间4 d,陈化时间对塑性的贡献甚小。据此认为除第Ⅲ类煤矸石不适合制砖以外,其他矸石均可作为制备绿色墙体保温砌块的原材料,混合破碎至-0.5 mm,陈化3天,适合制备绿色墙体保温砌块的需要。     

Population balance in confined comminution using a physically based probabilistic approach for polydisperse granular materials

A novel, simplified approach is presented in order to compute variations of grading in granular assemblies during confined comminution under quasi‐static compression. The method is based on a population balance equation and requires a breakage probability, considered here as a probabilistic phenomenon that takes into account the particle strength and the loading condition of individual grains. Under basic assumptions, a simple breakage probability can be defined in order to get a valuable result for engineering applications and powder technology. The size effect in the strength of individual particles is introduced according to Weibull's theory. The particle loading and the cushioning effect in the granular packing are accounted for by considering the orientations of the contact forces obtained from 3D discrete element method simulations of highly polydisperse materials. The method proposed could have a value for engineering purposes in powder technology and geomechanics and gives a general framework for further research developments based on population balance. Copyright © 2016 John Wiley & Sons, Ltd.     

Smooth particle hydrodynamics simulations of low Reynolds number flows through porous media

In this paper, a three‐dimensional smooth particle hydrodynamics (SPH) simulator for modeling grain scale fluid flow in porous media is presented. The versatility of the SPH method has driven its use in increasingly complex areas of flow analysis, including the characterization of flow through permeable rock for both groundwater and petroleum reservoir research. SPH provides the means to model complex multi‐phase flows through such media; however, acceptance of the methodology has been hampered by the apparent lack of actual verification within the literature, particulary in the three‐dimensional case. In this paper, the accuracy of SPH is addressed via a comparison to the previously recognized benchmarks of authors such as Sangani and Acrivos (Int. J. Multiphase Flow 1982; 8 (4): 343–360), Zick and Homsy (J. Fluid Mech. 1982; 115 :13–26) and Larson and Higdon (Phys. Fluids A 1989; 1 (1):38–46) for the well‐defined classical problems of flow through idealized two‐ and three‐dimensional porous media. The accuracy of results for such low Reynolds number flows is highly dependent on the implementation of no‐slip boundary conditions. A new, robust and numerically efficient, method for implementing such boundaries in SPH is presented. Simulation results for friction coefficient and permeability are shown to agree well with the available benchmarks. Copyright © 2010 John Wiley & Sons, Ltd.     

Electron Probe Microanalysis of Environmental Samples: Preparation of Reference Materials, Correction for Particle Size Effects and Representative Results on Sediments Recovered from Snow, Power Station Fly Ash and Bone Samples

In this paper we report the results of electron probe X-ray microanalysis (EPMA) that was used to study environmental materials. The mode of preparation and certification of reference samples based on a basaltic glass matrix for environmental applications of EPMA is described. These samples were prepared containing scandium, strontium and barium (from 0.03 up to 7% m/m) and an evaluation was made of homogeneity, their stability to local heating, followed by analysis by independent methods for certification of composition. Matrix correction procedures for the EPMA technique have been developed for particles having a size commensurable with the volume of X-ray generation. An analytical equation for the size factor is proposed and two techniques for selecting optimum conditions for the analysis of environmental samples by EPMA are reported. These procedures provided satisfactory results when utilized in analysing sediments recovered from snow, coal fly ash and the bones of animals and fish, results from which can be used as indicators for evaluating the pollution level of the lower atmosphere, surface and ground water, as well as revealing pollution mechanisms.     

Unfilterable "geoaerosols", their use in the search for thermal, mineral and mineralized waters, and their possible influence on the origin of certain types of mineral waters

 Many articles describing the unusual mobility of solid particles in the subsurface layers of the Earth's crust have been published in the last decades, especially in the geological literature. In an attempt to explain this phenomenon, several hypotheses have been developed. The one closest to the behavior observed in nature is based on quantum mechanics. Based on this phenomenon, a new geological prospecting method called Molecular Form of Elements (MFE) was developed in former Czechoslovakia during the 1970s. It has been widely applied since for various types of prospecting, including the search for thermal and mineral waters. When using the MFE method for prospecting, the relationship between the ascending mineral springs and the four directions of structural faults was discovered. The possibility of whether a process, similar to the one acting during the absorption of elements when using the MFE method, can be a source of dissolved solid particles during the creation of mineral waters is also discussed. Received: 3 March 2000 · Accepted: 11 July 2000     

Horizontal layered structure with heterogeneity beneath continents and island arcs from particle orbits of long-period P waves

We investigate the particle orbits of long-period (about 20 s) P waves observed with the global seismic network. By analysing 84 three-component seismograms recorded at 25 stations from 60 earthquakes occurring beneath 300 km, we quantitatively evaluate the orbits by three sets of eigenvalues and eigenvectors, using a covariance matrix method. The eigenvalues for P waves recorded at stations located on continents are explained by the standard horizontal layered structure model (iasp91). On the other hand, the orbits observed at stations close to island arcs are affected not only by the horizontal layered structure but also by heterogeneity due to subducting plates, mantle diapirs and so on. On the basis of a single-scattering model for a plane P wave, we quantify the heterogeneities by an isotropic scattering coefficient g0. Fitting the theoretical eigenvalues to the observed ones, we estimate g0 for the crust and upper mantle beneath continents to be less than 0.0005 km^-1, and the mean g₀ for the structure beneath island arcs to be about 0.0015 to 0.003 km^-1.