Moderation of dust explosions

Inherent safety is a proactive approach to process safety in which hazards are removed or minimized so as to reduce risk without engineered (add-on) or procedural intervention. Four basic principles are available to attain an inherently safer design—minimization, substitution, moderation, and simplification. The subject of the current paper is the principle of moderation as it applies to the prevention and mitigation of dust explosions.

Moderation can be achieved by processing a material under less severe operating conditions or by processing the material in a less hazardous form. With respect to the latter approach, it may be possible to alter the composition of a dust by admixture of solid inertants, or to increase the dust particle size so as to decrease its reactivity. Additionally, avoidance of the formation of hybrid mixtures of explosible dusts and flammable gases is an application of moderation of the material hazard.

Several examples are given for each of the above three forms of moderation. The discussion on admixture of solid inertants includes examples from the following industrial applications: (i) refractory materials manufacturing, (ii) food processing, (iii) power generation, (iv) industrial recycling, and (v) foundry shell mold fabrication. The importance of particle size consideration is explained first from the perspective of engineering tools such as the Dow Fire & Explosion Index, and professional guidance on the definition of a dust and suitable particle sizes for explosibility testing. Industrial examples are then drawn from the following areas: (i) rubber recycling and textile manufacturing, (ii) industrial recycling, (iii) wood processing, (iv) dry additive handling (polyethylene facility), (v) polyethylene production, (vi) carbon block recycling, and (vii) coal mining. The concluding discussion on hybrid mixtures includes brief cases from the process safety literature.     

城市海岸带环境管理模式优化研究——以青岛市胶州湾为例

我国的海洋污染日益严重,政府加大海洋环境保护力度势在必行。科学、有效的海洋环境管理对保护环境、提高资源利用效率起着非常重要的作用。但海洋环境并不是一维线性的系统,涉及系统的多维耦合,而海岸带又是与人类活动息息相关的重要部分。本文尝试以青岛市胶州湾海岸带环境管理模式为例,构建包含有"经济-人口-资源-环境-安全-行政(EPRESA)"六个子系统的多维耦合系统模型,并绘制出总流图,然后以此为管理模式的优化提供前提性分析,提出海岸带综合管理模式优化的对策建议。本研究认为,要改善现有的海岸带环境管理体系,应该制定综合性管理政策,建立可持续的融资机制,推进海岸带灾害与风险管理以及引导利益相关者参与管理。     

Trace monitoring of water-borne phenolics in the Klang River Basin

The Klang River Basin is located in the most densely populated region in Malaysia, with its heavy concentration of industries and population. A systematic study of the pollution to this river system caused by phenolic compounds have been carried out under this project. Analyses of water samples from the Klang River by high performance liquid chromatography (HPLC) with an ultraviolet (UV) detector at 280 nm have shown the presence of some priority phenolic pollutants.     

三江源生态移民对草地资源依赖性分析

基于移民、牧民访谈和问卷调查,对青海三江源泽库县生态移民的生活情况进行调查,分析移民对草地资源依赖性变化,以了解生态移民政策的成效与不足,并探讨现有政策中存在的相关问题,对三江源生态补偿政策和制度的制定完善提供参考和研究基础。研究结果显示:生态移民家庭经济收入有所提高,畜牧业收入占家庭总收入比例下降,生态补偿、务工、经商对于家庭收入的作用已明显显现。移民家庭从事畜牧业降为20.1%,务工家庭增加到37%,30.5%的移民参加过技能培训,但能源使用经济负担有所增加。53.90%的牧民愿意移民,但对移民后就业及生活设施建设仍有较大顾虑。总体而言,生态移民生活整体情况有所改观,移民后草地资源不再是家庭主要收入的基础。政府应完善技能培训体系,加快后续产业培育,重视生态移民工程前期规划,加大生态补偿资金支持力度。     

完善我国森林立法势在必行

通过对1998年长江、嫩江特大洪水的反思,指出了目前森林立法中存在的种种弊端,从而提出了完善我国森林立法的建议。     

连续倒塌中基于顶底角钢-腹板双角钢节点组件模型的研究

钢结构的抗连续倒塌能力一般取决于其抵抗局部损伤的能力,但这种能力往往取决于许多因素,目前还没有一个稳定可靠的判定方法。基于组件法建模原理将顶底角钢-腹板双角钢节点离散为多个对受力有贡献的基本组件,然后通过集成组件来模拟节点的受力特性,并依此构建了顶底角钢-腹板双角钢半刚性节点梁柱子结构的连续倒塌数值分析模型。结果表明:通过与试验结果比较,节点组件模型能较为准确地反映节点的断裂路径和受力发展过程,同时降低了计算成本。说明组件法在连续倒塌研究中具有重要的理论意义和应用价值,可作为连续倒塌研究的有利工具。     

工业化和城镇化进程中农民工问题的新探索

在工业化与城镇化大背景下,探讨我国农民工发展的特点和问题.首先从大中城市的利弊分析入手,探讨了小城镇发展的特点和存在的问题,分析发展小城镇是引导农民工合理流动的根本途径;然后从我国产业结构的现状分析,指出随着第三产业比例的增加尤其是服务韭的快速发展极大地推进了农村劳动力的转移,总结了产业结构合理化是加大农民工的就业力度的关键;进而从体制上探讨如何改革城乡的二元结构问题.总之,要解决农民工的问题,就要从根本上解决农民工在流动、就业、安置上的问题,这就应该从国家的体制方面、政策方面及人的观念上进行全面深入的思考.作为一个发展中国家,工业化和城镇化是农村劳动力转移的最终推动力量,工业化和城镇化的发展战略就是为了合理稳步地推进农村劳动力的转移.