西石门铁矿尾矿管道压力增高的原因分析及建议

针对西石门铁矿2006年6月选矿生产遇到的难题,从影响尾矿管道压力的因素——入选原矿质量、入选原矿处理量、管道内径变化、尾矿粒度出发,采取现场采样、选矿实验以及理论计算的方法,分析造成西石门铁矿尾矿管道压力增高的原因。以此次实验数据及相关经济技术指标为依据,对实际生产提出合理的建议和措施,进一步指导西石门铁矿选矿系统正常生产。     

钻孔煤体破坏渗流模型及在煤层卸压抽采中的应用研究

为对比分析顺层钻孔在护孔和未护孔条件下的抽采效果,考虑煤体扩容特性,采用煤体孔隙率和渗透率动态数学模型,结合D-P屈服准则,建立了钻孔煤体破坏—渗流的流固耦合模型。以超化煤矿2煤层相关物理参数为基础,开展了钻孔卸压破坏范围及抽采瓦斯数值模拟,结果表明：钻孔发生卸压破坏后,虽然未护孔钻孔卸压范围是护孔钻孔的1.3倍,其周围煤体渗透率和孔隙率均大于护孔钻孔,但钻孔更易塌孔堵孔,当抽采90 d时,护孔钻孔有效抽采半径为未护孔钻孔的1.3倍。现场瓦斯抽采测定数据表明,护孔钻孔平均抽采瓦斯浓度为未护孔的1.6倍,平均抽采瓦斯纯流量为未护孔的1.4倍,并有效缩短了钻孔抽采时间。     

基于K-means聚类的风压系数快速分区方法

提出了一种基于K-means聚类的风压系数快速分区方法。K-means聚类要求事先给出聚类数目k值,在风压系数分区应用中存在局限性。采取两种措施进行改进：一是预先限制k值范围,实现所有k值下的快速聚类。二是采用有效性指标确定最佳k值。分别以平屋盖、鞍形屋盖的两种代表性来流工况为例,说明和验证了风压系数分区方法。结果表明：分区方法能很好地完成不同几何形状屋盖、不同来流工况、不同类型的风压系数分区。     

超高压处理对牛初乳中IgG活性的影响

牛初乳中富含营养物质和多种活性成分,尤其是IgG的含量特别高。以产犊后48h内的牛初乳为原料,研究不同的超高压处理条件对牛初乳中IgG活性的影响,采用ELISA方法检测经过超高压处理后样品中IgG的活性。结果显示,在压力500MPa、温度35℃、时间20min条件下处理牛初乳,其IgG活性提高率达到最大。      

高压二氧化碳保鲜双孢蘑菇的工艺优化

为了优化高压二氧化碳(high pressure carbon dioxide,HPCD)保鲜双孢蘑菇的工艺,在单因素实验基础上,采用响应面法分析HPCD处理压力、处理时间和处理温度对双孢蘑菇硬度和颜色的影响并对其进行优化。结果表明,HPCD保鲜双孢蘑菇的最佳工艺条件为:处理压力0.3 MPa,处理时间3 min,处理温度17℃;与对照相比,该条件HPCD处理后的双孢蘑菇可以更好的保持其硬度和颜色,低温贮藏8 d后的硬度为191.7 N(提高了18.85%),褐变指数(BI)为33.13(降低了16.80%)。因此,HPCD技术可以应用于双孢蘑菇的贮藏保鲜,具有良好的前景。      

A Changing Light Environment Induces Significant Lateral CO2 Diffusion within Maize Leaves

A leaf structure with high porosity is beneficial for lateral CO₂ diffusion inside the leaves. However, the leaf structure of maize is compact, and it has long been considered that lateral CO₂ diffusion is restricted. Moreover, lateral CO₂ diffusion is closely related to CO₂ pressure differences (ΔCO₂). Therefore, we speculated that enlarging the ΔCO₂ between the adjacent regions inside maize leaves may result in lateral diffusion when the diffusion resistance is kept constant. Thus, the leaf structure and gas exchange of maize (C₄), cotton (C₃), and other species were explored. The results showed that maize and sorghum leaves had a lower mesophyll porosity than cotton and cucumber leaves. Similar to cotton, the local photosynthetic induction resulted in an increase in the ΔCO₂ between the local illuminated and the adjacent unilluminated regions, which significantly reduced the respiration rate of the adjacent unilluminated region. Further analysis showed that when the adjacent region in the maize leaves was maintained under a steady high light, the photosynthesis induction in the local regions not only gradually reduced the ΔCO₂ between them but also progressively increased the steady photosynthetic rate in the adjacent region. Under field conditions, the ΔCO₂, respiration, and photosynthetic rate of the adjacent region were also markedly changed by fluctuating light in local regions in the maize leaves. Consequently, we proposed that enlarging the ΔCO₂ between the adjacent regions inside the maize leaves results in the lateral CO₂ diffusion and supports photosynthesis in adjacent regions to a certain extent under fluctuating light.     

Mechanics of Reversible Deformation during Leaf Movement and Regulation of Pulvinus Development in Legumes

Plant cell deformation is a mechanical process that is driven by differences in the osmotic pressure inside and outside of the cell and is influenced by cell wall properties. Legume leaf movements result from reversible deformation of pulvinar motor cells. Reversible cell deformation is an elastic process distinct from the irreversible cell growth of developing organs. Here, we begin with a review of the basic mathematics of cell volume changes, cell wall function, and the mechanics of bending deformation at a macro scale. Next, we summarize the findings of recent molecular genetic studies of pulvinar development. We then review the mechanisms of the adaxial/abaxial patterning because pulvinar bending deformation depends on the differences in mechanical properties and physiological responses of motor cells on the adaxial versus abaxial sides of the pulvinus. Intriguingly, pulvini simultaneously encompass morphological symmetry and functional asymmetry along the adaxial/abaxial axis. This review provides an introduction to leaf movement and reversible deformation from the perspective of mechanics and molecular genetics.     

波节管承受外压失稳性能研究

本文通过有限元分析和试验验证两方面来讨论光管和波节管在失稳方面的问题,并从波距、节宽以及波数等方面对波节管失稳性能的影响进行了分析和讨论。     

长壁开采切顶短壁梁理论及其110工法——第三次矿业科学技术变革

为了深入了解近距离煤层群切顶留巷上覆岩层应力及变形演化规律,以白皎煤矿B₄煤层、B₃煤层、B₂煤层切顶成巷巷道2442、2443及2444运输平巷为研究对象,开展了3层煤回采巷道开挖物理试验研究,结果表明：①上煤层巷道切顶后,顶板卸压; 煤层开挖后,采空区顶板垮落并支撑巷道顶板,顶板增压; 煤层继续开挖,覆岩断裂,顶板卸压; 巷道顶板应力依次经历卸压、增压及卸压过程,其中,高位顶板应力增加较大,应力较高。②中部巷道切顶及煤层开挖后,上覆岩层压力同时向上煤层巷道围岩及本巷道采动破碎压实围岩转移,并在两巷道之间的上覆岩层中形成应力增高区。③下煤层巷道切顶及煤层开挖后,巷道围岩破坏严重,无集中应力,受前两次开挖卸压影响较大。④上覆岩层沿层理面出现错动变形,同时出现垂直拉伸剪切裂纹,采动影响越大,裂纹扩展程度越大。

     

煤系地层顶板岩溶地下水赋存特征研究

煤层瓦斯测压下向钻孔积水会导致测压不准,研究既能排水又不影响测压进程和测压结果的装置是下向钻孔测压亟待解决的难题。设计了自动排水装置,利用弹性膜实时感知排水时机, 实现了自动化排水;试验研究了弹性膜弹性参数,确定膜的最佳厚度为0.3~1.0 mm;基于气体压力差与毛细作用力原理,推算了最优排水区间;在此基础上研制出一种煤层瓦斯测压下向钻孔自动排水实验装置并开展排水试验。试验结果表明：在测压气室气压为0.152×10⁵ Pa,排水管管径为15 mm,毛细管内径为0.2 mm、数量为950根时,排水速度为0.444 3 cm³/s,该装置可以实现连续缓慢排水。