高温矿井回采工作面湿球温度的应用

利用回归分析的方法计算出湿空气焓值的湿球温度表达式,进而导出回采工作面热平衡方程的湿球温度表达式和风流的热交换方程。由于干球温度指标评价矿井气候条件具有片面性,引出了回采工作面进风临界湿球温度的概念。通过分析,得出回采工作面的进风临界湿球温度为25℃较为合适的结论。当回采工作面进风湿球温度低于25℃时,适量增加风量有利于工作面降温,当大于25℃时,增加风量对工作面降温反而有害。     

煤矿应急管理集成信息系统设计

针对目前煤矿企业在应急管理中存在的问题,通过对国内外应急管理技术的研究成果的学习和总结,进行煤矿应急管理信息系统的需求分析,在对应急管理的理论流程、基于案例推理（CBR）等理论进行深入研究的基础上,将人工智能、关键链方法和计划调度相关理论应用到人员管理和应急计划的制定和实施过程中,结合J2EE、SOA、GIS和GPS等技术,实现煤矿应急管理信息系统功能设计与集成设计,并借此推进煤矿企业在应急管理方面的发展,将事前预警与事后响应相结合,降低煤矿突发事件的危害程度。     

不同火源功率及火源—出口距离对隧道火灾临界风速的影响研究

由于隧道特殊的建筑结构,其发生火灾时的危害性,相比于其他类型的火灾要严重的多。在隧道的消防设计中,运用纵向风排烟是隧道火灾一项重要的消防措施,如何利用纵向风的特性来有效地引导隧道火灾烟气的运动需要进行系统的研究。运用FDS数值模拟的方法进行研究。结果显示,临界风速随着火源功率的增大而增大;并且随着火源与隧道出口距离的增大呈现出线性增长的趋势。对于6.0cm和9.0cm的火灾,临界风速与火源-出口距离关系式分别为 y=0.4+0.14x, y=0.5+0.11x。因此在消防实际应用中,应当充分考虑不同火源功率和火源在隧道中的相对位置对火灾烟气运动的影响,调节不同的排烟风速进行有效、合理的隧道排烟。     

基于灰色系统理论的煤矿人因事故关键因素分析

通过对煤矿人因失误事故致因因素进行分析,统计出相关的关键影响因素,运用灰色系统关联理论,根据国家安监局近十年煤矿事故统计数据,对煤矿人因失误事故影响类型进行了分析。以煤矿事故发生起数和事故死亡人数作为参考指标,计算和分析行为失误致因、个人违章、组织管理失误等十项主要与煤矿人因事故相关的灰色关联度,进而推算出这些因素的灰色关联序,确定出导致煤矿人因失误事故的关键因素,最终得到煤矿人因事故与关键影响因素之间的定量化分析结果。采用灰色关联理论对煤矿人因失误影响因素进行分析,能够很好地说明人因失误与各关键影响因素之间的权重关系,对煤矿人因事故主致因机理有更加深刻的理解,为煤矿事故的预防和控制提供重要的参考依据。     

水网地区漂浮输气管道安全评估方法研究

为防治水网地区河流穿越管道形成漂浮管段而发生事故,需要对漂浮管道进行安全评估。根据工程实例,建立水流作用下漂浮管道的力学模型,构建基于土弹簧法的有限元实体模型,采用有限元软件对漂浮输气管道进行仿真计算。然后,根据计算不同漂浮长度下的管道应力,分析管道最大应力比率在漂浮长度影响下的变化规律,建立漂浮管段安全评估模型。最后,结合实例对管道安全评估模型流程进行说明。实例分析结果简洁明了地反映出该漂浮输气管道处于安全运行状态,与实际情况相符,表明该安全评估方法是有效的。     

露天堆场防风抑尘网临界孔隙率的数值模拟

应用Fluent6.3对防风抑尘网及料堆周围流场进行数值模拟,通过研究不同孔隙率抑尘网与料堆周围湍流特性及料堆表面剪切力分布规律,确定了临界孔隙率.结果显示:高孔隙率(0.3、0.4、0.6)流动状态与无网工况一致,来流风沿迎风面贴附向上,风速逐渐增大,堆顶达到最大;低孔隙率(0、0.2)流态与无网迥异,迎风面处于涡旋中,风速向下,孔隙率为0时涡旋中心高于堆顶3m,孔隙率为0.2时涡旋中心位于堆高2/3处.孔隙率30.3时,料堆各表面剪切力变化趋势一致,与无网工况来流风同向,最大剪切力出现在堆顶.孔隙率为0.2时,作为最大起尘量的迎风面,其表面剪切力随高度先增大后减小,最大剪切力处于堆高3/5处.孔隙率为0.25时,湍流结构和剪切力分布发生突变,迎风面为贴附和涡旋复合流动,表面剪切力最小.据此确定来流风速6m/s,运用该几何模型时,临界孔隙率为0.25.     

农药类化合物对大型溞的毒性作用模式:与基线毒性化合物比较研究

农药在控制有害生物的同时,对水生生态系统产生较大的毒性效应。本文通过实验获得了25种基线化合物对大型溞的急性毒性数据,并与57种农药类化合物对大型溞的急性毒性数据进行比较研究,同时根据体外浓度LC_(50)、生物富集因子BCF和体内临界浓度CBR的关系,计算了这些化合物在大型溞体内的临界浓度,研究了农药类化合物对大型溞的毒性作用机理。结果表明,基线化合物在大型溞体内的临界浓度log1/CBR值在一个很窄的范围波动,而农药类化合物在大型溞体内的临界浓度log1/CBR值范围广且较高。这说明多数农药类化合物对大型溞为反应性毒性作用模式。其中,除草剂对大型溞的毒性显著低于杀菌剂和杀虫剂对大型溞的毒性。这可能是因为除草剂主要通过干扰植物光合作用、植物激素或植物分子合成发挥毒性效应,从而导致其对大型溞的生理系统难以发生反应性毒性效应。而杀虫剂和杀菌剂主要通过干扰生物神经系统、生殖系统、呼吸作用或大分子合成发挥毒性效应,因此易与大型溞生理系统发生生物化学反应,从而具有较高的毒性效应。本文分别建立了除草剂、杀菌剂和杀虫剂对大型溞的急性毒性QSAR模型。除草剂对大型溞的急性毒性机理较简单,其毒性与化合物疏水性程度和离子化程度有关;而杀菌剂对大型溞的急性毒性主要与化合物的标准生成热和极性表面积有关;杀虫剂对大型溞的急性毒性作用机理较复杂,它们对大型溞的毒性效应与其和生物分子之间的氢键和范德华力有关。     

WATERSHED BASED,INSTITUTIONAL APPROACH TO DEVELOPING CLEAN WATER RESOURCES1

ABSTRACT: Access to clean and sufficient amounts of water is a critical problem in many countries. A watershed approach is vital in understanding pollution pathways affecting water resources and in developing participatory solutions. Such integration of information with participatory approaches can lead to more sustainable solutions than traditional “crisis‐to‐crisis” management approaches. This study aims at applying a watershed based joint action approach to manage water resources. Since most watersheds have urban and rural sources of pollution and a wide disparity in access to and use of water, alternative solutions need to take an integrated approach through cooperative actions. An institutional model was applied to seven subwatersheds in Honduras to evaluate various sources and effects of water contamination and water shortages. Two specific pathways of water resources degradation were studied (contamination from coffee pulp manufacturing and urban nonpoint sources) to develop alternative solutions that mitigate downstream impacts of access to clean water. A locally driven joint mechanism to reuse coffee pulp in farming systems is proposed. Such an institutional solution can maximize benefits to both farms and the coffee pulp industry. A combination of education and investment in sanitary facilities in urbanizing areas is proposed to minimize urban sources of water contamination.     

METHODOLOGY AND EMPIRICAL ESTIMATES OF THE RESPONSE FUNCTION OF SORGHUM TO IRRIGATION AND SOIL MOISTURE1

ABSTRACT: This paper presents a methodology for the estimation of response functions of crops to irrigation and soil moisture. A system analysis framework is applied to describe the relationships involved. Two subsystems are distinguished, with the first one involving the relationship between irrigation decision variables and soil state variables, and the second involving the relationship between soil state variables and crop yield. A method for tracing and predicting soil moisture profile variations over time and depth is presented, and empirical estimates of the response function of grain sorghum to soil moisture are derived. In the specification of the response function the concept of “critical days” is applied with a “critical day” being defined as one where the soil moisture is depleted below a certain critical level. The paper provides empirical evidence for the usefulness of the approach     

Participatory Development of No-tillage Systems without Herbicides for Family Farming: The Experience of the Center-South Region of Paraná

It is currently estimated that 40 million hectares worldwide are cultivated through no-tillage systems (Derpsh, 1998). Small family farms account for less than 50,000ha, half of them located in South America's Southern Cone (Wall, 1998). Many hypotheses have been offered to explain why so few small farmers have adapted to this method. The most simplistic ones relate this limited adoption to small farmers' traditionalism and to their rejection of innovation. Others point to the low technological development of animal-drawn equipment needed for this technology or the low educational level of family farmers.Results of work done in the Center-South of Paraná, Southern Brazil, by AS-PTA¹ in partnership with the region's Forum of Family Farmers Organizations, challenge these hypotheses and draw attention to the need for new approaches and processes of research and extension if the goal is to disseminate and implement appropriate no-tillage systems among family farmers. One requisite is to lower production costs of this method through elimination of herbicides and using green manure and cover crops that shift the crop-weed balance in favor of crops.