Extraction of locked-up coal by strengthening of rib pillars with FRP——A comparative study through numerical modelling

In some of the coalfields in India, coal seams are only developed but no extraction of pillars is possible due to the presence of surface or sub-surface structures and also non-availability of stowing materials which leads to huge amounts of coal being locked-up underground. Spontaneous heating and fire, accumulation of poisonous gases, severe stability issues leading to unsafe workings and environmental hazards are the major problems associated with the developed coal pillars. So, there is a pressing need for a technology for the mining industry to extract the huge amount of coal locked-up under different constraints. In this study, the locked-up coal is proposed to be extracted by artificially strengthening the rib pillars. The detailed comparative study is carried out to know the increase of extraction percentage of locked-up coal by strengthening the rib pillars with FRP. Extraction methodology is designed and studied through numerical modelling for its stability analysis to evaluate its suitability of application in underground.     

粘钢抗弯加固预应力混凝土梁非线性有限元分析

利用大型通用软件ANSYS建立了粘钢加固预应力混凝土梁的有限元模型和非线性分析过程,并对计算和试验结果进行了对比,最后进行了混凝土强度、粘钢方式和粘钢厚度的参数分析。结果表明非线性有限元模型能过有效反映粘钢加固梁的性能,三面粘钢加固效果良好。     

强化功能菌菌种优筛及配比研究

为规范强化大曲的生产,适应西凤酒扩能及数字化生产需求,通过对强化霉菌的优筛、复壮及性能测试,获得优良的强化菌种,继而优化强化菌种的配比方案,使大曲性能更优。结果表明:(1)通过糖化力培养基筛选及菌株酶活测定,共筛选出6株强化霉菌,分别是黑曲霉M004-2、黑曲霉C556-22、酯化红曲霉-16、红曲霉C462-11、根霉S和根霉5,对其进行重新保藏;(2)对筛选出的菌株进行不同比例混合固态发酵试验,通过不同理化指标进行比较分析,得出红曲霉:黑曲霉:根霉=3:1:2的配比组合为最优组合。     

Constitutive modeling of reinforced concrete and prestressed concrete structures strengthened by fiber-reinforced plastics

A batch of constitutive models for steel reinforcing bar, prestressing tendon, concrete and fiber-reinforced plastic are proposed for the nonlinear finite element analysis of reinforced concrete structures, prestressed concrete structures, reinforced concrete structures strengthened by fiber-reinforced plastics and prestressed concrete structures strengthened by fiber-reinforced plastics. These material models have been tested against series of experimental data and good agreements have been obtained, which justifies the validity and the usefulness of the proposed nonlinear constitutive models.     

高层建筑结构构思与建筑创作

本文通过实例探讨了高层建筑创作合理进行结构构思，处理建筑功能，技术与艺术矛盾的方法和规律。     

快速更换斜井带式输送机强力皮带的方法

介绍了大同矿务局燕子山矿采用快速更换主斜井强力皮带的方法，说明了该方法具有速度快、效率高、花费人力少、质量高和安全可靠的优点。     

超高层建筑加强层与斜撑的组合效能研究

现代高层及超高层建筑中,加强层与斜撑的组合使用日渐普遍。本文建立了四个空间模型,通过对它们地震反应的对比分析,总结出了斜撑与加强层组合使用时结构位移和内力的变化规律,评价了斜撑和加强层的组合效能,为工程设计人员提供参考并提出若干设计建议。     

Experimental investigation of gas-tightness and electrical insulation of fuel cell stack under strengthened road vibrating conditions

Gas-tightness and electrical insulation are two important evaluation indexes of fuel cell vehicle safety. In this paper, the variation of gas-tightness and electrical insulation of fuel cell stack under long-term vibrating conditions are experimentally investigated through a 150 h strengthened vibration test. The load spectra applied in the test are simulated by the acceleration signals of the fuel cell stack, which are previously measured in a vehicle vibration test. The load signals of the vehicle vibration test are iterated through a road simulator from vehicle acceleration signals which are originally sampled in the strengthened road of the ground prove. The test results show that the hydrogen leak rate of the stack increases 1.5 times during the test. Additionally, the insulation resistance of the stack experiences a rapid decline at first, and then a steady linear decrease to 17.55% of the original value. It is observed that the decrease rate at the first stage is 25 times higher than the one at the second stage.     

Experimental investigation of the steady-state efficiency of fuel cell stack under strengthened road vibrating condition

The steady-state efficiency of the fuel cell stack is experimentally investigated in terms of steady-state hydrogen utilization, actual efficiency and maximum efficiency point through a 162 h strengthened vibration test in this paper, in order to analyse the steady-state performance of the fuel cell stack under long-term vibrating condition on strengthened roads. The load spectra applied in the test are simulated by the acceleration signals of the fuel cell stack, which are previously measured in a vehicle vibration test. The load signals of the vehicle vibration test are iterated through a road simulator from vehicle acceleration signals which are originally sampled in the strengthened road of the ground prove. The test results show that the steady-state hydrogen utilization of the stack decreases by 30.7% during the test. The maximum drop of steady-state actual efficiency is 21.0%. Additionally, the maximum efficiency point of the stack declines by 5.4%, while the corresponding current experiences an increment of 47.2 A. From the results it can be concluded that the strengthened road vibration exerts a significant influence on the steady-state performance of the fuel cell stack, which cannot and should not be ignored during the research.     

筋板布置型式对机床动态性能的影响

以M2120A内圆磨床为对象,比较了采用不同筋板型式后各主要零件及整机的动态性能。分析结果表明,依据零件的振型特点选用相宜的筋板型式可明显提高其动刚度,而且由改进后的各零件组合而成的整机磨床比原磨床具有更好的动态特性。