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。     

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。     

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.     

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。     

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.     

Injuries of the flexor tendons of the hand

Diagnosis of clear-cut severing of the two flexor tendons is simple and obvious. This is not true for isolated injury to a single tendon and for partial severing. In this case, careful clinical examination and routine surgical exploration of any wound with regard to the course of the flexor tendon is required. Surgery should aim at the least traumatic repair possible, followed by specialised rehabilitation directed by the surgeon. In the distal region, reinsertion into the bone is required. In other regions, suture consists of a the main suture with a continuous suture of the epitendineum. The region of the digital canal requires rigourous care due to its specific anatomy. The corollary to good surgical repair is rehabilitation, understood and complied with by the patient. Early mobilisation procedures are used predominantly in order to avoid the formation of postsurgical adherences.     

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.     

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)     

Formation of the structure of the weld metal upon the introduction of nanoparticles into the weld pool

The addition of nanodispersed powders to the area of welded joint is a promising control mechanism of controlling the properties of the weld metal. This article is aimed at determining the influence of TiN, TiCN, and WC nanoparticles (<100 nm) on the structure and the properties of the welded joint.     

Ultrastructure of the salivary bladder of the nine-banded armadillo

The nine-banded armadillo possesses a salivary bladder which is a dilated portion of the main duct of the submandibular gland at its origin. The wall of the bladder is composed of an epithelium, a submucosa and a thick coat of skeletal muscle. The ultrastructure of the epithelium reveals that it is complex and consists of three cell types: 1) principal cells, 2) light cells, and 3) basal cells. The general organization of the epithelium suggests that it is a transporting type of epithelium such as that found in the amphibian and reptilian and reptilian urinary bladders and the mammalian gall bladder. The submucosa is composed primarily of densely-packed collagen fibers. The skeletal muscle is very vascular and richly innervated.     

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。     

浅谈铜冶金过程的安全技术与事故预防措施

铜冶金是以火法为主的高温冶金过程,同时铜电解阳极泥又是回收金银等有价金属的重要资源。在冶金过程中,生产多在高温、高压、粉尘、有毒、腐蚀等环境下进行,为确保操作人员和设备的安全,必须特别注意安全防护措施的落实。     

平整机辊缝区域流体模拟计算及应用

四辊干平整机在轧制时,由于带钢和轧辊直接接触,在轧制压力下,干摩擦产生轧制粉尘,这些粉尘主要产生在辊缝区域,会随着带钢运行造成的气流,被带入辊缝,造成表面的缺陷。本技术通过引入流体场的模拟,根据粉尘特性、机架布置、气流、除尘口特性等要素模拟出靠近干平整机辊缝区域的气流特性,总结和设计出一套高速在线干平整机的辊缝除尘设备,将轧制粉尘有效地去除。     

混合机筒体危险截面的确定和强度校核

筒体装置是圆筒混合机的主体。由筒体、滚圈、大齿圈、筒体内附件等组成。本文分析了5B150 3.6 m×13 m圆筒混合机筒体上载荷的分布情况,确定了滚圈危险截面并根据建立的数学模型进行强度校核。     

Intraosseous schwannoma of the vault of the skull

Intraosseous schwannoma is a rare benign tumor of the bone with characteristic radiological and histological features. The most common sites of this tumor are mandible, sacrum, und vertebral bodies. Two cases, one of which is the first diagnosed with MRI, of this tumor in the vault of the skull are presented.     

铸造起重机端梁铰接轴联接固定结构的改进设计

八钢二炼钢区域的大吨位冶金铸造起重机为四梁四轨双小车结构,在使用过程中出现连接固定失效、铰接轴非正常磨损的情况。起重机端梁铰接点连接失效会造成起重机主梁与副梁分离的严重设备事故。介绍了对原设计的结构方式进行的改进设计,改进后消除了铰接连接失效的事故隐患。     

Ununited fracture of the hook of the hamate

Of nine ununited fractures of the hook of the hamate, eight were treated by surgical excision of the fragment. All eight patients had relief from persistent pain and regained the preinjury level of function. This fracture occurs frequently in athletes and is often not diagnosed because it can be demonstrated only by special roentgenographic views. It is concluded that this fracture may be less rare than is commonly believed and that surgical excision permits early return of function, especially in athletes and laborers who must be able to grip hard objects strongly.