董东矿沿空留巷切顶卸压对底板受力影响分析

以董东矿50107工作面为研究对象,通过数值模拟软件FLAC3D建立模型,对比分析窄矿柱、宽矿柱以及切顶沿空留巷情况下围岩及底板受力特征,确定切顶沿空留巷切顶对围岩的卸压作用。对比分析围岩受力情况,表明切顶沿空留巷卸压效果比较明显,对比分析围岩塑性区的底板破坏深度,表明有利于切顶沿空留巷卸压效果明显,切顶沿空留巷有很好的卸压效果,有利于矿山巷道围岩控制。     

抛光时间和表面粗糙度对硬度测试数据的影响

本文讨论抛光时间和表面粗糙度对金属材料布氏硬度测试数据的影响。试验结果指出,随着样品抛光时间的延长,HB值波浪式地变化;随着表面粗糙度的降低,HB值逐渐变小。分析指出,前者与抛光过程中磨面金属的加工硬化和随后的消失、及其循环往复有关;后者则是由表面粗糙度降低后,磨面上加工硬化层的减薄引起的。上述变化规律还受金属材料原始硬度的明显影响。     

加强烧结过程控制与稳定烧结矿质量

烧结矿的金属性能包括机械强度、氧化还原性和强度稳定性项指标,而影响这些因素种类繁多、错中复杂。介绍了烧结厂通过加强对烧结全过程的控制,稳定烧结矿金属质量的方法和效果。     

Some correlates of the empathy of the workers with the foreman.

Can a worker predict the perception of his own foreman? "The Test of Foreman-Worker Relationship was administered to 361 Israeli factory workers and their 51 foremen… . The prediction of the worker is more likely to succeed when the foreman's attention is oriented to the worker. Success is also more likely when the worker believes that the attention of the foreman is not oriented toward the worker… . Certain perceptions are easier to predict than others." (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Design and analysis of the tunnel connecting the beamcorridor and the spectrum hall of the CSNS

There is a tunnel connecting the beamcorridor and the target station in the spectrum hall in the CSNS project. The length of the tunnel is about 20 m. The shielding design of the tunnel is very significant for the persons working in the spectrum hall beca     

Simulation of the solidification of the melt in the Vanyukov furnace in the case of emergency stoppage

A mathematical model of the Vanyukov furnace, which makes it possible to predict the behavior of an object in the emergency operational mode (upon the disconnection of the oxygen supply) and develop an effective system of additional heating which damps the consequences of the emergency mode and lowers the costs for the renovation of the furnace operation, is created. It is shown how solidification upon cooling the furnace with time is simulated using the enthalpy and porosity method. The mathematical model is adopted for existing production conditions, which are weakly defined. The energy characteristics of the mode for the solidifying furnace bath, which ensures its holding for a long time in the ready state to rapid firing, are found. Thus, the problem of excessively expensive furnace firing after prolonged production stoppage is solved in the conjugated statement with a calculation of the heating system of the overbath space.     

Osteoma of the base of the tongue

A 14-year-old girl developed a firm mass at the base of the tongue. Computed tomography indicated marked density suggesting either a foreign body or bony tissue. A thyroid scan confirmed the presence of a normally sized and positioned gland. The mass was removed in toto and found to be an osteoma. This is the first report of a case in which the diagnosis of this rare developmental lesion of the tongue was achieved preoperatively based on clinical and radiologic information. This experience should lead to greater awareness of this entity in the future. Recognition of this entity in the pediatric age group is especially useful in avoiding misdiagnosis of other, potentially more aggressive types of tongue mass lesions. Our case demonstrates that it is possible to detect this entity using computed tomography. The dense calcification is truly characteristic of the tumor and may be relied upon to exclude alternative soft tissue mass lesions. While other forms of osseous and cartilagenous neoplasms, such as extraskeletal osteosarcoma and chondrosarcoma, have been reported arising in the tongue, their malignant nature should otherwise be readily apparent. Osteoma of the tongue is the favored diagnosis when mature bone tissue is imaged at the base of the tongue.     

增大穿孔机送进角 提高穿孔效率的实践

通过增大穿孔机送进角,减小轧辊出口锥角,从而提高了穿孔效率,降低了单位能耗,收到了较好的效果。     

浅谈降低工程成本的方法

随着全球化经济危机的日益迫近,以及国家投资结构的调整,全国建筑行业正面临着重新调整,承包市场竞争愈演愈烈,全行业进入了微利时代。因此,要想在危机中立足于建筑行业,必须把成本降低到最合理的地步,而降低工程成本的关键在于搞好事前计划,事中控制,事后分析。     

Effect of the nanoparticle shape on the temperature of the onset of powder sintering

The sintering of needle and spherical particles is considered in terms of a diffusionless sintering model based on the idea that the sintering of nanoparticles smaller than 70 nm is determined by their fluctuational melting. It has been shown that the temperature of the onset of sintering of needle particles is lower than that of spherical particles of the same mass. According to calculations performed for copper nanopowders, the temperature of the onset of sintering of needle particles is 6% lower than that of spherical particles of the same mass.