露天矿最终边坡角的快速拉格朗日有限差分法研究

某露天钼矿,矿体为石英粗面岩,下盘为流纹岩,上盘为粗面凝灰岩。原设计坑底标高为630 m,最终边坡角上盘实际取48°,下盘取50°。二期设计坑底标高为500 m。为了探索露天坑底延伸后的最终边坡角,分别应用ANSYS和快速拉格朗日有限差分法(FLAC-3D),研究矮台阶和高台阶开采的边坡稳定性及局部边坡加固方法。结果表明:应用ANSYS软件在D-P准则下研究最终边坡角及边坡稳定性是不合适的;由FLAC-3D得出经济合理的最终边坡角为48°~50°。为确保边坡的长期稳定,应用长8 m的锚索加固局部台阶,可减小其潜在的受拉区中的拉应力值;按一根锚索承担的台阶潜在的受拉区的岩体自重施加锚固力是合理的;若高台阶坡面角不变,边坡稳定性略有恶化;降低高台阶坡面角可加大边坡的稳定性。在莫尔-库伦准则下FLAC-3D适合搜索岩质边坡的潜在受拉区,据此确定最终边坡角技术可行、经济合理、简便适用。用该方法研究最终边坡角,克服了极限平衡法必须事先假定滑动面的弱点。     

采空区精确建模信息系统实体模型交互接口开发

随着矿业的快速发展,Surpac,Dimine,3DMine等三维矿业软件在矿业领域得到了广泛的应用。为进一步完善自主研发的采空区激光扫描三维精确建模信息系统功能,在解析stl,dxf及dtm格式文件的数据结构及其三维实体数据存储规律的基础上,成功地开发了基于上述三种实体模型存储文件格式的采空区三维实体模型交互接口,实现了信息系统与目前主流三维矿业软件之间三维实体模型的交互。实用表明,所开发的接口能有效实现信息系统与其他三维矿业软件之间采空区三维模型的交互与共享,进一步完善了信息系统的模型数据输入输出功能,提高了其应用价值。     

煤层液态CO_2爆破增透促抽瓦斯技术研究

为增加煤层透气性,提高瓦斯(甲烷)抽采效率,基于损伤力学和空气动力学,研究液态CO2爆破的原理,分析爆破过程中爆破器主管内高压气体的压力时程变化。采用FLAC3D数值软件,建立煤层液态CO2爆破有限差分本构模型,计算不同地应力下单孔爆破有效影响半径,数值模拟多孔连续爆破。模拟结果表明,单孔爆破有效影响半径随着地应力的增加近线性减小;有控制孔时多孔爆破影响范围明显大于无控制孔时。在井下进行液态CO2爆破工业试验。其结果是,爆破后煤层透气性系数提高17.49~22.76倍,平均瓦斯抽采浓度和混合气体流量分别增加56.4%和42.8%。     

碟形越浪式波能发电装置的三维数值模拟

基于计算流体力学软件的三维数值模拟技术,分析了碟形越浪式波能发电装置的越浪性能,通过构建基于水气两相VOF(Volume of Fluid)模型的三维数值波浪水槽对该装置进行三维数值模拟研究,数值计算结果与物理试验结果相互对比验证较为吻合,验证了所构建的三维数值波浪水槽的可靠性,通过考察装置的坡度、导流叶片个数、干舷高度对越浪性能的影响确定装置的最优结构参数。结果表明,在装置的斜坡面边缘增加回流板可减少波浪的反射,提高装置的越浪性能。在数值模拟中将装置的斜坡面边缘处安装回流板对碟形越浪式波能发电装置参数进行优化,通过分析回流板的长度对装置越浪性能的影响来探索最优回流板长度。     

Emissions of C&D refuse in landfills: A European case

A field study was developed in a new landfill for refuse from construction and demolition (C&D) material recovery plants of small size (4 Ha.) in Europe, with the aim of evaluating the liquid and gas emissions in this type of facility at a large scale. It included characterization of the materials, monitoring leachate and gas quantity and composition. Besides thermometers, piezometers and sampling ports were placed in several points within the waste. This paper presents the data obtained for five years of the landfill life. The materials disposed were mainly made up of wood and concrete, similar to other C&D debris sites, but the amount of gypsum drywall (below 3% of the waste) was significantly smaller than other available studies, where percentages above 20% had been reported. Leachate contained typical C&D pollutants, such as different inorganic ions and metals, some of which exceeded other values reported in the literature (conductivity, ammonium, lead and arsenic). The small net precipitation in the area and the leachate recirculation into the landfill surface help explain these higher concentrations, thus highlighting the impact of liquid to solid (L/S) ratio on leachate characteristics. In contrast to previous studies, neither odor nuisances nor significant landfill gas over the surface were detected. However, gas samples taken from the landfill inside revealed sulfate reducing and methanogenic activity.     

Input–output analysis in an oil-rich economy: The case of Azerbaijan

This paper aims to provide empirical research to identify the linkages between final demand–total output, final demand–total supply, value-added ratios and prices, and also to analyze total factor productivity growth using input–output framework for 25 sectors. Studying the input–output tables for 2001 and 2006, the research estimates impact and response multipliers of non-oil sectors, as well as non-oil trading sectors. The results are important from the view of development of non-oil trading sectors and diversification of the economy in order to avoid the “resource curse”.     

The view from below: ‘lock-in’ and local procurement in the African gold mining sector

Through linkage creation, commodity extraction has the capacity to support local industrial production and capabilities building. Drawing on the experience of supplying inputs into the East African gold mining industry, this paper examines the constraints experienced by local suppliers arising from the purchasing procedures of large mining corporations and specialist construction companies contracted to construct these mines. Lead firms become locked-in to particular ways of working which minimise the opportunities that local suppliers have in providing products and services. After reviewing the situation for local mining suppliers in East Africa, the paper examines ways in which lead firms, the suppliers themselves and others (governments and industry associations) can better support local supplier involvement.     

Comparison of the droplet size spectra produced by rotary atomizers and hydraulic nozzles under simulated aerial application conditions

Abstract

A wind tunnel was used to characterize the droplet size spectra of liquid sprays from several different atomizers and nozzles used under simulated aerial application conditions. The atomizers included a D8–46 nozzle, a Through Valve Boom (TVB) nozzle, and rotary cage and drum atomizers.

The D8–46 hydraulic nozzle was evaluated, using water, at orientations of 0, 10, 20, 30, 40, 50, 60, 70, 80 and 90° relative to 145 and 180 km/h airstreams. The TVB nozzle was evaluated using water, water with isopropyl alcohol, and water with a non‐ionic surfactant at airstream velocities between 130 and 180 km/h. The rotary atomizers were evaluated at different rotation rates, flow rates of water and an insecticide, in 130 and 180 km/h airstreams.

The volumetric droplet size spectra parameters (D_vo.x) decreased as the angle of the D8–46 nozzle and the airstream velocity increased. Empirical models were developed to predict these values for different windspeed and nozzle angle conditions. The TVB nozzle produced larger droplets than the other atomizers under similar conditions, with a decrease in the D_vo.x parameter values as the airstream velocity increased.

The D_vo.x parameter values produced by the rotary atomizers increased as the liquid flow rate increased, and as the rotation rate and airstream velocity decreased, and were lower for the insecticide than for water. The slotted rotary drum atomizer gave the best control over droplet size, generally producing mono‐modal droplet size spectra where the other atomizers often produced bi‐ and multimodal spectra.     

Detectability of phenoxy herbicides by chlorophyll fluorescence

Abstract

Trace amounts of 2,4‐D ‐ which does not cause visible damage in plant ‐ are detectable in plant leaves by chlorophyll fluorescence regeneration in two ways. (I) In illuminated leaves the level of first and second fluorescence peak differ in treated and untreated leaves. (2) By taking buffer solution (pH=8.6) in dark‐adapted leaves under vacuum, the first, second and the other fluorescence decrease levels differ in untreated and 2,4‐D or MCPA treated leaves.     

Differential enhanced degradation of cis‐ and trans‐1,3‐D in soil with a history of repeated field applications of 1,3‐D

Abstract

The fumigant 1,3‐dichloropropene (1,3‐D) is considered to be a potential alternative to methyl bromide. The degradation rates of cis‐ and trans‐l,3‐D in soil from a treated site during three successive annual applications of 1,3‐D progressively increased with an increase in the number of annual applications. The enhancement was greater for trans‐l,3‐D degradation than cis‐l,3‐D. In untreated soil, the degradation rates of the two isomers were similar. The enhancement lasted slightly longer than 2 years after annual field application of 1,3‐D had ceased. A single field reapplication of 1,3‐D to the treated site that had not been treated for 2 years resulted in resumed differential enhanced degradation of cis‐ and trans‐l,3‐D. Microorganisms were responsible for the enhanced degradation.