330 kV安通开关站直流接地现象的处理及分析

在发电厂和变电所中常有发生直流接地现象,接地现象产生的原因与当时的运行方式、操作情况以及气候影响等因素有关。文章通过对330 kV安通开关站直流接地现象的分析,指出了产生这起现象的原因以及处理方法,为今后工作中处理类似问题提供了依据,积累了经验。     

OPGW允许的最高温度

当电力系统发生短路故障时,流过OPGW的短路电流会使OPGW发热升温。当温度超过200℃时,不但会影响OPGW的性能(光纤的着色层变硬、退色,能量损耗增大),而且易造成OPGW发生鸟笼现象、断股现象。短路电流容量是衡量OPGW温度特征的尺码,文章介绍了有关标准,对各种典型结构的OPGW进行了短路电流容量和温升关系的分析,从而说明设计和选用OPGW时,遵循OPGW标准规定的重要意义。     

不同位双回采空间在矿脉分枝复合膨缩严重的削壁充填采矿中的应用

不同位双回采空间试验应用于金厂沟梁金矿15^#脉，矿块地顶编号9154，应用该法主要是为了解决矿脉分枝复合膨缩严重的矿块回采问题，同时也能提高矿石的回采回收率，提高采矿回益．并为回采类似地质状况的矿块积累经验。     

英语歧义现象的语言学阐释

在有关歧义现象大量研究的基础上，试图从语音学、词汇学、句法学和语用学等几方面对歧义现象进行阐释，以期读者对歧义现象有一个较全面和理性的认识，同时也提供了一些消除歧义的方法。     

The design,development and assessment of electrically heated gloves used for protecting cold extremities

Abstract

The design and development of electrically heated gloves for alleviating pain in vaso-spastic disorders, such as Raynaud's disease, is described. Clinical assessment of these conditions from the temperature patterns produced by infrared thermography is discussed. The effect of electrically heated gloves on tissue perfusion in individual patients can be assessed by thermography. A ‘hot’ stress test to determine the degree of vaso-spasticity using the gloves to provide a ‘hot challenge’ has been developed and is described.     

采煤工作面消突综合评价技术体系

在消突评价机理及现状研究的基础上,依据相关法律法规,提出了一套采煤工作面消突综合评价技术体系,补充了目前消突评价技术在低指标突出方面验证的缺陷,简化了评价程序,消除了评价指标重复考察。通过现场应用实践,验证了该技术的可行性及准确性。     

Hamstring stretching significantly changes the sitting biomechanics

The tightened hamstring connecting the tibia to the pelvis provides more posterior pelvic tilting and consequent backward curvature of the sacral and lumbar vertebrae. Therefore, the study goal was to quantitatively investigate the effect of hamstring and low back stretching on the trunk biomechanics in a system-level perspective. Twelve healthy subjects performed two stretching interventions (hamstring only (HS); hamstring + low back (HLS)) for 40 s on two separate days. They sat on a stool before and after the intervention while capturing trunk kinematics and EMG. In addition, the lumbar flexion angle at which the L4 paraspinals deactivate (i.e., flexion-relaxation phenomenon; FRP) was monitored while trunk flexion-extension trials, performed before and after the protocol. The FRP onset angle was captured to verify the biomechanical changes in the lower extremity and trunk systems. In the results, the stretching intervention significantly increased the reaching distance by 6.3 cm in the sit-and-reach test performed immediately before and after the intervention. The flexible hamstring improved the lumbar flexion angle and head postures in both the HS and HLS. However, the HLS induced laxity in lumbar passive tissues, as confirmed by changes in the FRP, and significantly increased co-activation in the low back. The stress-relaxation of the hamstring and surrounding passive tissues could help to maintain better lumbar flexion angle (i.e., lumbar lordosis) while sitting. Periodic HS for 40 s without any significant lumbar flexion may be recommendable for office workers who sit for long periods.     

实时功率控制在激光切割机的应用研究

利用光纤激光切割机进行板材切割的时候拐角处常有过烧的现象,这是由于激光切割尖角时,长时间加热带来热量积聚所造成的,为克服该缺点,本系统基于速度控制的激光功率控制,可有效降低烧角现象。实现结果表明该方法可以有效的提高零件的切割质量。