排序方式: 共有12条查询结果,搜索用时 15 毫秒
1.
2.
3.
薄煤层机械化开采新技术 总被引:2,自引:1,他引:1
介绍了我国薄煤层机械化开采存在的主要问题,及国、内外薄煤层开采技术和相应的装备,重点介绍了刨煤机和螺旋钻薄煤层开采的回采工艺、技术特点和适应条件,具有一定的借鉴价值。 相似文献
4.
猴子岩水电站地下厂房硐室群工程地质条件复杂,岩体节理裂隙发育、受多条断层和挤压破碎带影响,加之布置于中-高地应力区域,施工过程中硐室围岩的变形和破坏较为明显,为确保工程施工安全,须对整个硐室群施工期的应力变形及稳定进行分析。结合相关设计参数和开挖支护实施方案,建立了猴子岩地下厂房硐室群的三维有限差分计算模型,并对其地应力场分布进行了反演,在此基础上对硐室群整个施工过程进行了全程模拟。计算结果表明:随着硐室开挖临空面的扩大,上下游边墙应力松弛现象较为明显,在断层出露带、机坑隔墙底部出现了不同程度的应力集中;开挖过程中围岩位移逐渐增大,在硐室连接处出现了大变形。设计支护方案实施后可以较好地限制围岩变形,减小塑性区面积,工程实践说明该方案较为合理。 相似文献
5.
采用电弧熔炼法制备Co38Ni34Al27Mn1磁控形状记忆合金,并对合金进行热处理.采用金相显微镜、X射线衍射仪及振动样品磁强计等研究热处理工艺对Co38Ni34Al27Mn1合金显微组织、相结构及磁性能的影响.研究结果表明:1573 K加热冰水淬火后得到β相和γ相,而1623、1673 K加热冰水淬火后合金中可观察到板条状马氏体,且β相、γ相和马氏体相共存.随着热处理温度的提高,合金晶粒长大,γ相体积分数减小,马氏体含量增加,饱和磁化强度从42.51 emu·g-1增加到45.43 emu·g-1,矫顽力从48 Oe减小到30 Oe;在1673 K淬火,随加热保温时间的增加合金晶粒变大,饱和磁化强度从44.31 emu·g-1增加到47.29 emu·g-1. 相似文献
6.
7.
目前,我国在工程施工领域,已广泛实行监理管理体制。文章对煤田地质钻探工程中监理现状及问题进行了分析,结合施工中具体工作程序,对监理工作要点进行了阐述,并说明了实行监理工作的效果及体会。 相似文献
8.
Shrinkage cavity has significant influence on macrosegregation in steel ingots. An arbitrary Lagrangian-Eulerian(ALE) model based on volume averaging method is developed to predict the coupled formation progress of macrosegregation and shrinkage cavity during solidification of steel ingots. The combined effect of thermal-solutal convection and solidification shrinkage on macrosegregation is considered in the model. A specially designed mesh update algorithm is proposed to consider the formation of shrinkage cavity. The streamline-upwind/Petrov–Galerkin(SUPG) stabilized finite element algorithm is adopted to solve the conservation equations. Two solution methods for the energy conservation equation are proposed, i.e. the temperature-based solver and enthalpy-based solver. A Pb-48 wt.%Sn solidification benchmark is used for validation. Then, the ALE model is applied to a Fe-3.6 wt.%C industrial steel ingot. The formation progress of macrosegregation coupled with shrinkage cavity is predicted. By comparison with the predictions of the finite element model and finite volume model, the effect of shrinkage cavity formation on macrosegregation is investigated. Results show that the formation of shrinkage cavity can significantly change the segregation region and segregation degree at the hot top. It is demonstrated that the ALE model can predict the coupled formation of macrosegregation and shrinkage cavity in steel ingots. 相似文献
9.
针对朴素贝叶斯(NB)分类器在分类过程中存在诸如分类模型对样本具有敏感性、分类精度难以提高等缺陷,提出一种基于多种特征选择方法的NB组合文本分类器方法。依据Boosting分类算法,采用多种不同的特征选择方法建立文本的特征词集,训练NB分类器作为Boosting迭代过程的基分类器,通过对基分类器的加权投票生成最终的NB组合文本分类器。实验结果表明,该组合分类器较单NB文本分类器具有更好的分类性能。 相似文献
10.