A review of energy associated with coal bursts

A coal burst is defined as a rapid expulsion of coal(and potentially gas) from the boundary of the roadway. Rock and coal fractures together with micro seismic vibration is a common occurrence during mining, however, it is very uncommon for coal and rock to be propelled into the roadway. Irrespective, such occurrences do occur and appear to require significantly more energy than is available from strain energy release during coal cutting. The sources of energy which can contribute to the propulsion of coal from the face or ribs are typically strain energy from the surrounding ground, seismic energy from a rapid rupture of the ground in the vicinity, or rapid expansion of gas from within the burst source area. The aim of this paper is to briefly review the bursts which may be related to strain energy, seismic energy and gas energy.     

Model test of helical angle effect on coal loading performance of shear drum

The work presented in this paper focuses on improving coal loading performance of shear drum.Employing the similarity theory,we carried out a dimensional analysis of the correlation parameters which in...     

非规范观测站岩层移动角计算方法分析

鉴于某矿区地表移动观测站的非正规布置,根据观测线上三个临界变形值位置,确定地表影响椭圆分布区域的边界点;建立独立坐标系,将边界点与坐标原点进行联合观测,计算出边界点相对于原点的坐标值,然后将各个坐标值代入椭圆方程,求取地表影响椭圆半轴长,根据移动角与开采边界的空间几何关系,计算出矿区的岩层移动角.研究表明,该方法简洁实用,能够满足开采沉陷工程的实际要求.     

Analysis of monitored ground support and rock mass response in a longwall tailgate entry

A comprehensive monitoring program was conducted to measure the rock mass displacements, support response, and stress changes at a longwall tailgate entry in West Virginia.Monitoring was initiated a few days after development of the gateroad entries and continued during passage of the longwall panels on both sides of the entry.Monitoring included overcore stress measurements of the initial stress within the rock mass, changes in cable bolt loading, standing support pressure, roof deformation, rib deformation,stress changes in the coal pillar, and changes in the full three-dimensional stress tensor within the rock mass at six locations around the monitoring site.During the passage of the first longwall, stress measurements in the rock and coal detected minor changes in loading while minor changes were detected in roof deformation.As a result of the relatively favorable stress and geological conditions, the support systems did not experience severe loading or rock deformation until the second panel approached within 10–15 m of the instrumented locations.After reaching the peak loading at about 50–75 mm of roof sag, the cable bolts started to unload, and load was transferred to the standing supports.The standing support system was able to maintain an adequate opening inby the shields to provide ventilation to the first crosscut inby the face, as designed.The results were used to calibrate modeled cable bolt response to field data, and to validate numerical modeling procedures that have been developed to evaluate entry support systems.It is concluded that the support system was more than adequate to control the roof of the tailgate up to the longwall face location.The monitoring results have provided valuable data for the development and validation of support design strategies for longwall tailgate entries.     

四肢角钢格构柱的分析与设计

对某工程四肢角钢格构柱进行了工程分析与设计,对其强度、刚度、缀板抗剪、整体稳定性和分肢稳定性进行了讨论,明确了分肢的稳定性是格构柱设计的控制性因素。采用STAAD.pro有限元软件建模仿真,计算结果表明设计安全合理。板单元的网格划分应根据不同工程板件的长度、宽度和厚度,选择不同的网格尺寸大小,不宜划分过粗或过细。     

一类具有非线性传染率的SEIS传染病模型的分析

讨论了一类具有常数输入且传染率为非线性的SEIS流行病数学模型,给出了决定疾病灭绝和持续生存的基本再生数R0.当R01时,无病平衡点全局渐近稳定;当R01时,利用第二加性复合矩阵证明了唯一地方病平衡点的全局渐近稳定性.     

一类潜伏期和染病期均有传染力的SEIR模型的稳定性分析

研究了具有一般形式的接触率潜伏期和染病期均有传染力的SEIR模型,给出了无病平衡点和地方病平衡点存在的条件,得到了疾病流行的阈值.证明了无病平衡点和地方病平衡点是全局渐近稳定的.     

大倾角大采高综采工作面高产高效实践

淮南矿业集团潘北矿1121（3）工作面,其煤层赋存状况是典型的大倾角、多断层、＂三软＂、高瓦斯、复杂地质条件。本文就综采技术在大倾角煤层的应用过程中所涉及到的问题进行分析并加以解决,实现了大倾角综采工作面的高产高效。     

高职2010届毕业生就业心理调查与分析

文章通过对安徽电气工程职业技术学院2010届毕业生就业心理状况的调查,从毕业生就业认知、择业心理倾向和就业情绪状态等方面进行逐项分析,客观地认识高职学生的就业心理状态和就业指导需求,提供给家庭、学校和社会,对毕业生及时给予关注与引导,为学生调整择业心态、把握职业生涯机会、积极就业服务。     

具有密度依赖扩散的捕食食饵模型的稳定性分析

研究了一类具有非线性扩散的捕食食饵模型,讨论了耦合反应扩散系统平衡态的不稳定性,在有界区域上给出了不稳定的充分条件。结果表明交叉扩散可以导致平衡态的不稳定性。     

一类具扩散的环境数学模型的稳定性

许多环境数学模型是用常微分方程表示的,它只考虑了时间对种群密度的影响.研究了一类具扩散的环境数学模型,用反应扩散方程组来表示这些模型更显合理.首先利用比较原理讨论了抛物问题解的正性及有界性,然后运用上下解方法及相应的单调迭代序列研究其动力学行为,得到了正平衡点渐近稳定的充分条件.     

Analysis of gateroad stability at two longwall mines based on field monitoring results and numerical model analysis

Coal mine longwall gateroads are subject to changing loading conditions induced by the advancing longwall face. The ground response and support requirements are closely related to the magnitude and orientation of the stress changes, as well as the local geology. This paper presents the monitoring results of gateroad response and support performance at two longwall mines at a 180-m and 600-m depth of cover.At the first mine, a three-entry gateroad layout was used. The second mine used a four-entry, yieldabutment-yield gateroad pillar system. Local ground deformation and support response were monitored at both sites. The monitoring period started during the development stage and continued during first panel retreat and up to second panel retreat. The two data sets were used to compare the response of the entries in two very different geotechnical settings and different gateroad layouts. The monitoring results were used to validate numerical models that simulate the loading conditions and entry response for these widely differing conditions. The validated models were used to compare the load path and ground response at the two mines. This paper demonstrates the potential for numerical models to assist mine engineers in optimizing longwall layouts and gateroad support systems.     

带扩散的基于比率的捕食模型的分析

建立了带扩散的基于比率的捕食模型,讨论了模型的一致持久性,应用特征子空间分解与线性化的方法得到了模型正平衡点局部稳定性的充分条件,进一步通过构造适当的Lyapunov泛函的方法得到了正平衡点全局稳定性的充分条件。     

带扩散的基于比率的捕食模型的分析

建立了带扩散的基于比率的捕食模型,讨论了模型的一致持久性,应用特征子空间分解与线性化的方法得到了模型正平衡点局部稳定性的充分条件,进一步通过构造适当的Lyapunov泛函的方法得到了正平衡点全局稳定性的充分条件.     

相互竞争的两种群中具有饱和传染率的SIRS模型的稳定性分析

建立了相互竞争的两种群中具有饱和传染率的SIRS传染病模型;讨论了各平衡点存在性,得到正平衡点存在的条件;证明了各平衡点的局部或全局稳定性.结论表明,当种内传染强度或交叉传染强度足够大时,正平衡点将存在且局部渐近稳定.     

一类具有非线性传染率的传染病模型性态分析

研究了一类具有一般传染率寄生虫宿主模型的全局性态.利用微分方程定性理论得到了宿主和寄生虫共同绝灭的条件;进一步得到了宿主和寄生虫共存即系统正平衡点存在的条件,证明了正平衡点只要存在一定是全局稳定的.     

具有饱和发生率的SIR模型的持久性和稳定性

研究了一类具有饱和发生率的虫媒传染病模型.确定了疾病是否流行的阈值R0.如果R0≤1,无病平衡点是全局渐近稳定的,疾病逐渐消失;如果R0＞1,地方病平衡点是渐近稳定的,疾病将流行最终导致地方病产生.     

一类具有时滞的恒化器模型的定性分析

恒化器模型是一个简化了的微生物培养模型.本文以时滞为参数,利用特征根法分析了系统平衡点的稳定性和hopf分支,得到了系统在平衡点处局部渐近稳定和出现hopf分支的充分条件,是对已有结果的有益补充.     

具有收获率的三种群捕食模型的定性分析

研究了一类具有收获率的三种群捕食模型,讨论了该模型平衡点的存在条件及性态,并利用Routh—Hurwitz准则得到了模型唯一正平衡点是渐近稳定的.     

不同定义下的带角圆回转铣刀的优劣

回转铣恨是加工复杂曲面的重要工具,目前流行多种刃口曲线设计方法,因此比较其优劣具有工程价值,通过介绍不同定义下的螺旋角对应的带角圆的柱状回转铣刀在刃口曲线、二轴联动NC加工中的进给速度等问题的不同之处,指出了与经线成等角的定义下这种铣刀设计、NC加工及使用均具有明显优点。