谈谈电子汽车衡首次检定中注意的问题

本文主要介绍电子汽车衡首次检定之前、检定中及大秤量电子汽车衡偏载测试方式等问题,目的是使电子汽车衡首次检定一次通过。     

电化学控制浮选在乌拉嘎金矿生产中的应用

针对乌拉嘎金矿难选冶矿石性质,北京矿冶研究院与现场技术人员合作进行了电化学控制浮选的试验研究,取得了突破性进展。于1997年该技术应用到生产实践中,获得精矿品位为56．67g/t、金回收率90．18％的好指标,分别比原生产指标提高19．47g/t和3．38个百分点。试验研究结果表明,电化学浮选对难选冶金矿石有深入研究和推广应用价值。     

以自蔓延高温合成SiC颗粒为增强体的光学/仪表级铝基复合材料

尝试采用自蔓延高温合成（SHS）、具有近球特征且表面粗糙的新型SiC颗粒,以替代传统的角状磨料级SiC颗粒,作为光学/仪表级的高体分SiCp/Al复合材料的增强体。研究结果表明：与传统角状SiC颗粒相比,SHS-SiC颗粒的无棱角,近球形几何特征,使其附近铝基体中的应力集中程度显著降低,进而使材料的强度包括表征尺寸稳定性的微屈服强度明显提高：SHS-SiC颗粒所特有的粗糙表面形貌,使SiC-Al之间的界面结合通过机械镶嵌机制得到了进一步的增强,跨越界面的载荷传递效率进一步提高,并表现为复合材料的弹性模量有所提高。     

基于Web的AutoCAD自动考试与评分系统的开发

介绍了系统的设计思想和主要功能,讨论了系统的试题库、自动组卷、交互考试和自动评分等各功能模块的设计原理与实现方法。     

山东招远脉状金矿矿体数学特征及研究意义

通过考查招远脉状金矿矿体的统计特征、空间特征及结构特征,定量及定性地研究矿体的各属性、标志的变化规律,提供矿床的成因信息,验证现行勘察方案的合理性。对矿体各种标志值变化趋势的研究,还有助于发现矿化规律,进行矿体的深部预测,制定切实可行的勘探方案。     

某低品位金矿无氰堆浸工艺工业试验研究

介绍了某低品位金矿无氰浸堆工艺工业试验结果,采用无氰堆浸工艺可有效地从低品位金矿石中回收金,而且浸出率高,浸出时间短,无毒,有推广应用价值。     

加快推行新热轧钢筋标准满足市场需求

分析了包钢执行新的热轧钢筋标准所面临的问题 ,并通过分析新Ⅲ级热轧钢筋的性能 ,阐明了推广使用40 0MPa新Ⅲ级热轧钢筋的必要性 ,提出了解决执行新标准和生产 40 0MPa新Ⅲ级钢筋等问题的有关建议     

低品位金矿石井下柱浸试验研究

地下浸出技术对开采低品位金矿石有良好前景 ,井下环境内的柱浸试验表明地下浸出可以实现金的直接回收 ,而且金的回收率在将浸出矿石粒度控制在合适范围内时可以达到经济要求的水平     

An approach to simulate the motion of spherical and non-spherical fuel particles in combustion chambers

The objective of this paper is to identify a numerical method to simulate motion of a packed or fluidized bed of fuel particles in combustion chambers, such as a grate furnace and a rotary kiln. Therefore, the various numerical methods applied in the areas of granular matter and molecular dynamics were reviewed extensively. As a result, a time driven approach was found to be suited for the numerical simulation of particle motion in combustion chambers. Furthermore, this method can also be employed to moving boundaries which are required for the present application e.g. travelling grate. The method works in a Lagrangian frame of reference, which uses the position and orientation of particles as independent variables. These are obtained by time integration of the three-dimensional dynamics equations derived from the classical Newtonian approach for each particle. This includes the keeping track of all forces and momentums acting on each particle at every time step. Viscoelastic contact forces include normal and tangential components with viscoelastic models for energy dissipation and friction. The particle shapes are approximated by spheres and ellipsoids with a varying size and ratio of the semi-axis accounting for the variety of particle geometries in a combustion chamber. For these shapes the overlap of particles during contact is expressed by a polynomial of 4th order in the two-dimensional case and a polynomial of 6th order in the three-dimensional case. A new algorithm to detect two-dimensional elliptical particle contact with sufficient accuracy was developed. It is based on a sequence of coordinate transformations and has demonstrated its reliability in numerous applications. Finally, the method was applied to simulate the motion of spherical and elliptical particles in a rectangular enclosure, on a travelling grate, and in a rotary kiln. Received: 16 November 2001     

谈新Ⅲ级热轧带肋钢筋的推广应用

与原Ⅲ级钢筋相比,新Ⅲ级热轧带肋钢筋具有工艺性能和力学性能优良,节约钢材15％以上等优点。但在推广应用过程中,尚存在认识不足和建筑、设计、采购不配套等问题。为此,建议加大宣传力度,提供示范工程,拓宽销售渠道,完善生产工艺等,以加快新Ⅲ级热轧带肋钢筋的开发和推广应用步伐。