Influence of Lithological Characters of Coal Bearing Formation on Stability of Roof of Coal Seams

Lithology is one of the important factors influencing the stability of roof of coal seams. In order to investigate this, the phenomenon of underground pressure and distribution of pressure were studied by using the local observation and simulation test with similar materials. The observation results show that the distance of initial weighting and periodic weighting of the mudstone roof is shorter than that of sandstone roofs. The sandstone roof with a high strength has a longer distance of initial weighting and periodic weighting, the abutment stress on the working face is big and the height of caving and fracture zone is high. The peak point of abutment stress in the sandstone roof is near to the working face and the pressure bump is inclined to occur. The result is contrary to that in case of the mudstone roof with a low strength. While in the transition zone of nipped sandstone, roof rock-mass is broken and is poor in stability, therefore, it is difficult to hold the roof.     

Non-isothermal Kinetics of Pyrolysis of Three Kinds of Fresh Biomass

The pyrolysis kinetics of three different kinds of fresh biomass （grass： triple A, wheat straw, corn straw） in nitrogen flow were studied by thermogravimetric analysis at five different heating rates. The kinetic parameters of the pyrolysis process were calculated using the method of Ozawa-Flynn-Wall and the mechanism of reactions were investigated using the method of Popescu. It was found that the values of activation energy varied in different temperature ranges. The pyrolysis processes are well described by the models of Zhuravlev （Zh） and valid for diffusion-controlled between 200 ℃ and 280 ℃, by Ginstling-Brounshtein （G-B）, valid for diffusion-control between 280 ℃ and 310 ℃, for first-order chemical reaction between 310℃ and 350 ℃. by Zhuravlev （Zh） valid for diffusion-control between 350 ℃ and 430 ℃ and by the one-way transport model when temperatures are over 430 ℃.     

Electrochemical determination of Gibbs free energy of formation of magnesium ferrite

The standard Gibbs free energy of formation of magnesium ferrite was determined by means of two types of solid state electrochemical cells: one using MgZr4(PO4)6 (MZP) as the solid electrolyte and the other using CaF2 as the solid electrolyte. The first cell was operated in the range of 950 to 1100 K. The second cell was operated in the range of 1125 to 1200 K. The reversibility of the cell EMFs was confirmed by microcoulometric titration. The Gibbs energy changes of magnesium ferrite relative to component oxides were calculated based on EMF measurements and are given by following expressions, respectively: △G(o)Ⅰ = -3579-15 T (J/mol) and △G(o)Ⅱ =6258-24.3 T (J/mol). The results obtained from two different cells are consistent with each other. The results also are in agreement with Rao's and Tretjakov's data in the measured temperature range. When the Gibbs free energies of formation of MgO and Fe2O3 were substituted in the reaction, the Gibbs free energies of formation of MgFe2O4 was obtained in two temperature ranges and the formations are shown as follows: △G(o)Ⅰ Formation = -1427394 360.5 T (J/mol) and △G(o)Ⅱ Formation = -1417557 351.2 T (J/mol).     

Optimal Control of Aeroelastic StochasticVibration of Aerocraft

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Journal of Central South University of Technology

1 Aims and scope Central South University (CSU) is one of Chinese key universities, which is affiliated with the Ministry of Education. "Journal of Central South University of Technology" (ISSN 1005-9784, CODEN JCSTFT) is sponsored by CSU.     

Two Classes of Models of Granular Computing

1 Introduction Basic ideasand methods of granularcomputing have been employed to problem solvingin many ap- plied fieldsfor a long time.In granularcomputing one usesgroups ofelements (calledgranules)instead of individualelements.Main reasonsfornecessityof…     

Product of spaces of doubly periodic arrays

A characterization of the space generated by the Hadamard product of doubly periodic arrays is presented, and the results of Zierler and Mills are extended to higher dimensions.     

Application of photobioreactors to cultivation of microalgae

0　INTRODUCTIONHighcelldensityandindustrialproductionofmi croalgaecanberealizedbyphotobioreactorswhichprovidenecessaryconditionsformicroalgaecellbreedingandvalu ablesubstanceaccumulation .Mostmicroalgaearephotoautotrophy ,sothecultureprocesscanbeaccomplishedinaphotobioreactor.Inor dertorealizehighcelldensitycultureofmicroalgae ,manyfactorsmustbeconsideredwhileaphotobioreactorisde signed :First ,highratiooflightsurfaceareaandvolumeforincreasinglightutilizationratioofmicroalgae .Second ,app…     

Evaluation of Security of Mine Ventilation Systems

A mine ventilation system has a deterministic function for the ~fety of coal production and for the control of mine accidents. So, it has an important meaning to evaluate the security of a mine ventilation system. This paper studied the evaluation index system of the security of a mine ventilation system, and the security of a mine ventilation system was dc,described quantitatively in the safety degree. Finally, an example of the seurity evaluation was given.     

鄂尔多斯盆地查布水源地地下水 水化学特征及其影响因素

根据94件水化学样品的分析结果,对查布水源地地下水水化学特征及其空间分布规律进行了研究,并结 合含水层沉积环境及补径条件探讨了地下水化学成分的影响因素,以期为水源地水质保护提供依据。结果表 明:地下水水化学类型呈现明显的水平分带性,东部地下水中阴离子以HCO- 3为主,地下水水质一般较好,矿化 度多小于1g/L;西部地下水中阴离子以SO2- 4、Cl-为主,水质变差,矿化度明显增高;研究区硝酸盐污染比较明 显,F-局部超标,矿化度超标也比较明显;水质受含水层的沉积环境和地下水补径条件及人畜活动的影响明显。 水源地开采后,其影响会加大,因此应制定合理的水源地保护方案。     

煤炭基地水污染研究理论体系探讨

以煤炭基地的水体为研究对象,以煤炭基地水污染研究理论体系的建立为研究重点,在分析中国能源形势和煤炭基地发展现状的基础上,通过查阅大量文献资料,并结合陕北煤炭基地实际情况,有针对性地提出煤炭基地水污染研究理论体系框架,具体分析了该体系五个组成部分的研究目的、研究内容和研究成果用途,在此基础上以陕北煤炭基地水污染问题为研究实例实践这一理论体系。结果表明:煤炭基地水污染研究理论体系由煤炭基地水污染背景条件研究、现状研究、机理研究、发展趋势研究和防治对策研究组成;陕北煤炭基地超过80%的地下水属于轻微污染和未污染,地表水存在一定程度的污染;窟野河大部分水化学组成从上游向下游呈先升高后降低的趋势;陕北煤炭基地未来地下水主要污染区分布在榆林市榆阳区、金鸡滩镇、神木县锦界、神木县城、大柳塔镇、府谷县城等;对原有污染严重的企业进行技术改造做到清洁生产,在企业相对集中的区域采取污水厂统一处理进行,新建企业必须进行污水处理设计,对生活污水采取土地渗滤或污水厂处理,固体废弃物要做无害化处理,农业生产中要求合理施肥。     

泾源县地下水水质多元统计分析

为了给泾源县地下水合理开发利用与新农村建设提供基础理论支持,采用泾源县45个地下水水样的水化学资料,利用聚类分析和主成分分析对泾源县地下水水化学特征和水质状况进行了研究.基本描述性统计结果表明,研究区地下水水质基本满足生活饮用水卫生要求.聚类分析表明,进行指标聚类后,类的个数并未比聚类前明显减少,表明地下水各指标之间相关关系不明显.主成分分析结果表明,可以用9个独立的主成分代表原始19个指标因子,每个主成分反映了不同的水质指标以及各指标之间的关系.多元统计分析为泾源县地下水水质评价和水质管理提供了一种新方法.     

沙湖水质的因子分析

为了控制沙湖水体富营养化发生机理,探讨主要驱动因子及变化规律,根据沙湖2002—2004年的水质监测数据与空间数据,采用因子分析中的主成分分析法将沙湖的水质参数概括为5个主成分,利用surfer软件和kriging空间内插法,研究了湖泊水质各个主成分的科学内涵、空间分布特征、意义及年季均值变化规律.结果表明,藻类生长环境因子(F1)是沙湖富营养化的主要驱动因子;建立了富营养化因子(F2)与F1的模拟方程,并在表征与预测湖泊富营养化方面作一些基础研究.     

水土相互作用与土细观结构变异的X射线衍射分析

城市建设改变了水-土-电解质之间的平衡状态，地下水因扰动而日益“变异”，水土相互作用引发组分变异从而引发土结构发生变化，土结构应按三层次划分，即微观-细观-宏观结构，这样有利于甄别各自的作用与贡献，为此提出细观结构概念，通过构筑试验环境并进行X射线衍射测试，对原有衍射峰数、剩余衍射峰数、消失衍射峰数、新增衍射峰数分析发现，水土作用引发的结构变化来自于细观结构的变异，证实了在城市常温、常压、缓慢的地下水变异环境下，细观结构是水土相互作用发生、发展的“平台”及主要场所。     

Groundwater impact of open cut coal mine and an assessment methodology: A case study in NSW

Large scale open cut coal mining operations have significant impacts to groundwater in surrounding areas in both active and post-mining phases. The prediction of water inflows into a surface mine excavation is one of the many components involved in mine design phase. Groundwater performance also reacts to mining activities from the operational, economic and safety implications perspective. Under NSW planning legislation, as part of the comprehensive risk assessment, a groundwater impact assessment has to be conducted for a coal project to predict and mitigate the impacts in consideration of the government requirements. In this paper, the groundwater assessment modelling of mine pits was discussed in predicting of groundwater inflows and reviewing analytical and numerical approaches. A methodology of groundwater impact assessment for an open cut mine in NSW with a three-dimensional groundwater flow model Modflow Surfact demonstrated its functions in simulating the project's impacts on the groundwater regime. The key findings with mitigations are discussed and recommended in the paper to reduce impacts on groundwater and fulfil regulation requirements in NSW.     

矿区煤矸石淋溶对周边地下水环境污染分析

为了研究煤矸石中重金属元素对环境的污染情况,在河南巩义市内某煤矿区采集了煤矸石及周边浅层地下水样品。采用淋溶试验法及电感耦合等离子体质谱法(ICP-MS)分析测定了煤矸石及地下水中部分重金属元素的含量。结果表明:该地区煤矸石中元素Cr和Pb的含量较高;堆放在地表煤矸石随着时间的延长,淋溶出煤矸石中的元素总量随之增高,但溶出趋势各异;塌陷区的浅层地下水中除Cr和Sr元素外,其它元素的含量均高于非塌陷区对应的元素;塌陷区浅层地下水样品中Cr、Cu元素以及非塌陷区浅层地下水样品中Cr元素的含量偏高,分别为17.6、59.4和22.8 g/L。根据元素淋溶规律,对比塌陷区与非塌陷区元素含量,推断塌陷区浅层地下水中Cu和Pb元素值较高与矸石山有关。     

水文地质条件对白额勘探区煤层气富集的影响

地下水水动力场对煤层气富集具有明显影响。在研究区东部,煤储层埋藏浅,地下水的径流作用相对较强,煤层气被径流逸散。研究区西南部,煤储层埋藏深,地下水由本区东北浅部向西南深部顺层径流,对煤层中向上扩散的气体起到了封堵作用。矿区西南部为地下水低水位等势面区域,地下水严重滞留,有利于煤层气富集保存,是煤层气富集的有利区域。研究结构显示,地下水化学场特征同样影响煤层气富集。地下水滞留区域与高矿化度中心一致,同样与区域富气中心分布一致。这说明滞留或弱水力交替地下水是煤层气富集成藏的有利水文地质条件。     

基于主成分方法的浑浊水体组分的光谱探测分析

浑浊水体是水色遥感的重要研究对象,其光谱特征由浮游植物(叶绿素a含量)、无机悬浮物和可溶性有机物3个组分控制,利用光谱识别浑浊水体的组分信息对于光谱解混和组分的定量反演具有重要意义. 基于2010—2016多年太湖水体野外测量的数据,以水体光谱数据的协方差矩阵和相关矩阵为输入进行主成分分析,对比特征值分解(EVD)、奇异值分解(SVD)、非线性迭代偏最小二乘法(NIPALS)3种求解方法以及白化后处理对水体组分的识别作用. 结果表明,基于相关矩阵的SVD方法对浑浊水体组分的识别效果优于其他算法,获得的前3个主成分载荷累计贡献率为98.8%,依次代表了水、叶绿素a组分和悬浮泥沙组分信息; 白化后处理没有明显的优化作用.     

邯郸市地下水水化学类型分布及污染物成因分析

利用邯郸市地下水水质监测数据,采用O.A.阿列金分类法对地下水进行了水化学类型分类,确定该地区地下水水化学类型以HCO_3-Na型为主。在此基础上对邯郸市地下水的污染物及超标情况进行统计,分析污染成因。结果表明:邯郸市地下水超标物质主要为溶解性总固体、总硬度、氯化物、硫酸盐、氨氮、氟化物等,其污染原因主要是原生污染。