π型钢循环迈步支架在开采中厚煤层中的应用

在中厚煤层开采中,通过改进采煤工艺,采用π型钢循环迈步式支架代替高档炮采工作面常规的铰接顶梁支护工艺,在减少煤炭丢失的同时提高了资源回收率,也杜绝了老空区因丢失的煤炭自燃而引发的矿井火灾。

循环式巷道超前支架系统的应用

煤矿综采技术发展到今天,现有的巷道安全支护主要有U型钢、工字钢金属支架,锚杆、锚网以及其他联合支护的方式。随着采煤工作面的不断推进,巷道超前段压力发生前移,需要在工作面出口超前段进行加强支护。煤矿在进行现代综合机械化开采作业时,普遍存在超前压力较大的情况,若不进行有效的支护,不仅影响工作面采煤作业效率,还可能导致较大的安全隐患。为了解决上述问题,本文主要介绍一种循环式超前支架装置,阐述它的结构、原理、功能特点和使用环境。

以“三期全架式”游戏环境创设路径支持幼儿深度学习

环境是教师支持幼儿深度学习的路径起点,因此支持幼儿深度学习游戏环境创设离不开其核心要素以及实践路径的探索。为实现支持幼儿深度学习游戏环境,教师可通过赋能儿童、分期分重点、以问题为驱动、可循环可利用等策略保障支持幼儿深度学习的“三期全架式”游戏环境创设路径的实施,创设支持幼儿深度学习的空间环境。

Effect of carotid artery stenting surgery combined with nimodipine on cerebral anterior circulation hemodynamics

Objective To evaluate the effect of carotid artery stenting combined with nimodipine on cerebral hemodynamics by comparing and analyzing the change of anterior cerebral blood flow before and after treatment through transcrania Doppler （TCD）. Methods Twenty patients with ischemic cerebrovascnlar disease were detected in blood flow velocity of bilateral middle cerebral arteries （MCA） and anterior cerebral arteries （ACA） and artery pulsatility index with TCD before and two weeks after treatment. Results After treatment, TCD examination showed dynamic changes in blood flow significantly, lpsilateral MCA flow velocity significantly increased; ipsilateral ACA flow velocity did not change significantly; there was no significant increase in the contralateral MCA flow velocity; flow rate decreased significantly in contralateral ACA. Conclusion Carotid artery stenting combined with nimodipine treatment can cause anterior cerebral hemodynamic changes in ipsilateral hemisphere and significantly improve blood flow