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21.
22.
通过对航空公司安全目标控制现状的分析,得出了前馈控制中维修隐患查找不力,现场控制中员工自控和领导监督缺乏针对性、安全目标激励作用大打折扣、规章手册不利于查找,以及公司的反馈控制名存实亡等问题。并提出改进意见:针对维修隐患查找提出了新的查找机制;对员工安全指标排序,作为控制和监督的依据;引进目视管理,增强安全目标的激励作用;建议为维修员工提供能够快速查找相关手册项目的设备;使用滚动计划法制定安全计划,并借用其反馈框架,引入因果图查找产生偏差的原因。 相似文献
23.
The study focuses on evaluating factors that farmers consider relevant in adopting cassava production in five semi-arid zone
of West African countries. The study is based on primary data randomly collected as part of collaborative study of cassava
in semiarid zones of Africa (COSCASSA) village level survey from five West African countries namely: Nigeria, Ghana, Chad,
Niger and Burkina Faso. This study models effects of farm, farmer and technology specific factors on the decision of semi
arid farmers to adopt cassava into their farming system. By way of threshold decision models—Probit and Logit models, the
estimation of each country and the pooled data adoption models reveal different adoption models for the countries considered.
For each country, different variables appeared as major adoption shifters. Comparatively, the adoption models for Nigeria
and whole region appear to have the highest significance variables, being seven in number. This is followed by Chad (6), Ghana
(4), and Burkina Faso and Niger with three each. For the variables considered, distance to nearby urban market appears a major
adoption shifter in all the country, except for Niger. This is closely followed by contact with extension, variety, pest/disease
resistance and livestock feeds, which appear significant in four of the countries. Membership of cooperative societies appears
as the least adoption predictor, which is only significant in Chad republic. The study therefore recognizes the importance
of varietial characteristics and farmers’ characteristics in acceptance of cassava as a major root tuber crop in the semi
arid region of West Africa.
Readers should send their comments on this paper to: BhaskarNath@aol.com within 3 months of publication of this issue. 相似文献
24.
模拟了车用工况下燃料电池发动机脉冲式排氢的特点,设计开发了一套质子交换膜燃料电池的尾气净化系统,并以5 kW燃料电池的尾气排放为例,研究其净化效果。研究了电池阳极排放氢气缓冲前后尾气中氢气浓度的变化,以及不同空速条件下氢气的去除效果。结果表明:电堆阳极排放氢气经过缓冲处理后,尾气中氢气浓度趋于平稳,大部分工况下处在2%以下,达到了安全处理的要求;尾气中氢气的去除效果与空速密切相关。对自制的整体式催化剂而言,当空速低于20000 h^-1时,氢气的去除率能达到约95%,而当空速达到39270 h^-1时,氢气的去除率仅为10.9%。鉴于这一问题,提出通过采用尾排空气的分流手段调整催化燃烧反应器对空速的要求,以提高尾气中氢气的去除率。 相似文献
25.
26.
渗滤液污染包气带中铁的形态变化 总被引:1,自引:0,他引:1
从渗滤液场龄和包气带岩性两方面出发,研究了新、老渗滤液对亚粘土和细砂包气带环境中Fe的含量及存在形态的影响。结果表明:新、老渗滤液分别能使细砂包气带介质中除残渣态以外Fe的含量增加16.68%或降低13.82%。亚粘土比细砂作为包气带介质更能缓冲渗滤液对介质中Fe的影响程度,其受影响范围在包气带0~20 cm深度处。当亚粘土为介质的包气带被新渗滤液污染后,其表层介质中碳酸盐结合态Fe的含量会增加15倍之多,为缓冲渗滤液Fe的污染做出了巨大贡献,但这部分Fe的存在也是潜在的二次污染源,在环境pH急剧变化的情况下,它可能会引起地下水高铁污染。 相似文献
27.
Reclamation and revegetation of fly ash disposal sites - Challenges and research needs 总被引:1,自引:1,他引:0
Haynes RJ 《Journal of environmental management》2009,90(1):43-53
Coal-fired power generation is a principal energy source throughout the world. Approximately, 70-75% of coal combustion residues are fly ash and its utilization worldwide is only slightly above 30%. The remainder is disposed of in landfills and fly ash basins. It is desirable to revegetate these sites for aesthetic purposes, to stabilize the surface ash against wind and water erosion and to reduce the quantity of water leaching through the deposit. Limitations to plant establishment and growth in fly ash can include a high pH (and consequent deficiencies of Fe, Mn, Cu, Zn and P), high soluble salts, toxic levels of elements such as B, pozzalanic properties of ash resulting in cemented/compacted layers and lack of microbial activity. An integrated organic/biotechnological approach to revegetation seems appropriate and should be investigated further. This would include incorporation of organic matter into the surface layer of ash, mycorrhizal inoculation of establishing vegetation and use of inoculated legumes to add N. Leaching losses from ash disposal sites are likely to be site-specific but a sparse number of studies have revealed enriched concentrations of elements such as Ca, Fe, Cd, Pb, and Sb in surrounding groundwater. This aspect deserves further study particularly in the longer-term. In addition, during weathering of the ash and deposition of organic matter during plant growth, a soil will form with properties vastly different to that of the parent ash. In turn, this will influence the effect that the disposal site has on the surrounding environment. Nevertheless, the effects of ash weathering and organic matter accumulation over time on the chemical, physical and biological properties of the developing ash-derived soil are not well understood and require further study. 相似文献
28.
29.
吨量煤体的自燃过程实验模拟研究 总被引:4,自引:0,他引:4
为更好地弄清矿井实际的煤自然发火规律,利用装煤量达5吨的大型实验台对两种烟煤分别进行了自燃模拟实验。大煤量的实验能够很好地模拟煤矿中煤低温氧化和传热传质共同作用导致的发火过程,实验得到的自然发火期与煤矿实际发火期也是一致的。实验中煤样从缓慢氧化变为快速氧化的临界温度为100~110℃。当煤温低于,临界温度时,煤样的升温受到空气流带走热量和向外界散热的影响很大,因此夹层水的保温作用就很关键。当煤温超过临界温度后,反应加快,温度急剧上升,散热的影响明显降低,反应主要受限于氧气的供应情况。 相似文献
30.
卫生防护距离、大气环境防护距离,其定义相近、设定途径相似,但两者又有不同。故在环境影响评价大气环境预测分析时对大气环境防护距离、卫生防护距离的概念极易混淆。本文以某县殡仪馆建设项目为例,详细分析建设项目设置防护距离的设置条件,帮助环评工作者理解防护距离设置原则,防止出现"在环境保护法规和导则要求下盲目划定、划大防护距离"的技术错误。 相似文献