氧化铝厂蒸发器发生应力腐蚀的原因分析与防治

对氧化铝厂蒸发器发生应力腐蚀的危害性作了介绍 ,描述了应力腐蚀裂纹的特征 ;对应力腐蚀产生的原因进行了分析 ,并提出了防治措施     

Analysis of competition models in periodic medium

We propose special models (the so-called D-systems) with periodic delta-functions being used as the growth velocities of the populations. This allows to build, in a practically explicit form, corresponding Poincare mapping and to reveal a series of “paradoxical” phenomena and selection criteria in the dynamics of the competitors. For the analysis of non-autonomous models, new general principle of inheritance of a series of local properties by the global Poincare shift mapping is worked up. Specifically, key heritable properties are determined for non-autonomous competition models. The selection criterion for competitive selection, based on the concept of the universal allowance constant, is derived in this work.     

Study on convection and dispersion characteristics of dense gases in urban environment considering trees

Although several studies on the dispersion of heavy toxic gas released from ruptured tanks on vehicles during transportation have considered complex terrain such as urban buildings, the influence of trees on the flow field in urban areas during gas dispersion tends to be ignored. In this study, a Computational Fluid Dynamics (CFD) model was proposed to investigate the characteristics of gas release and dispersion from loaded vehicle in the urban environment. In this model, the tree crown was treated as a porous medium, and the influence of drag due to the crown was incorporated into the model by a momentum source term through a user-defined function. In this study, the dynamic characteristics of chlorine (Cl₂) dispersion under the conditions of building distribution, tree species and porosities were comprehensively analysed, to cover the influence of urban complexity, leaf density, and tree planting configuration. The results show that compared with flat terrain, the presence of urban buildings will prolong the dense gas retention time and increase the dangerous distance. It is found that the horizontal dispersion distance can increase by 63% and the isosurface of 25 ppm hazardous gas can increase by 130% with the introduction of buildings. Compared with the terrain with only buildings, the introduction of arbors or shrubs can result in a 147% or 359% increase in the maximum concentration. Also, trees will prolong the dispersion duration. It is also found that the higher the porosity, the less the wind blocking effect, and the weaker the ability of capturing gas. The wind field affected by arbores and shrubs are different in height, and arbores capture more Cl₂. Planting short shrubs around buildings can effectively reduce the spread of harmful gases.     

The adoption of green business practices among small US Midwestern manufacturing enterprises

Manufacturers around the world green their businesses for a variety of reasons, including competitiveness, social responsibility, and external stakeholder pressure. However, small and medium enterprises (SMEs) are thought to lag behind larger ones in the adoption of green business practices. This paper explores the motivations for US Midwestern SMEs adopting a variety of green business practices, using a survey of 59 SMEs in the tool and die manufacturing industry. The majority of firms appear to be internally motivated to implement green practices – driven primarily by cost and competitiveness concerns, more than by social responsibility concerns. External coercive pressure from government or customers does not appear to be a significant motivation for these SMEs. However, informal pressure through government incentives and support programs, as well as mimetic pressure through peer learning via industry associations, appear to be more effective in helping these SMEs to further ‘go green.’     

基于公众视角的中小化工企业环境风险研究

中小化工企业尽管能给当地政府带来可观的社会和经济效益，但同时也对其周边环境和居民健康造成严重威胁，已成为影响地方可持续发展的重要隐患。然而，公众如何看待中小化工企业造成的环境风险、企业与政府的环境管理和污染改善策略如何，目前还鲜有深入研究。本文基于河北省X县化工厂周边居民问卷调查(N=550)，旨在了解公众对当地化工厂环境风险及管理的认知状况，分析影响公众环境风险认知的主要因素，并提出相应的政策建议。结果表明：了解化工厂管理情况和环保局监督情况的受访者分别占10.9%和7.5%；64%的受访者认为化工企业建成后环境质量变差，受访者认为化工厂给当地环境质量和居民健康带来风险的可能性比带来社会、经济利益的可能性更大。Spearman相关分析表明，受访者教育程度、家庭收入、生活经历等都会影响受访者的风险认知情况。最后基于调查结果从政府、企业环境信息的及时发布、化工企业排污管理以及政府、企业与公众的风险沟通方面提出改善管理的举措。     

新型活性焦干法脱硫脱硝脱汞反应塔流场的模拟与优化

在CFD软件Fluent中,选择k-ε湍流模型,多孔介质模型和SIMPLE算法,对新型脱硫脱硝脱汞反应塔内的三维流场进行数值模拟,结果发现,反应塔入口处烟气流场存在大漩涡。为消除漩涡,使穿过活性焦层的烟气均匀化,以充分利用活性焦层的空间来提高脱除效率,提出在入口处加装弯曲导流板,并通过相对标准偏差确定最优导流板长度。同时模拟了在最优喷氨位置处加装涡旋混合器时氨气和烟气的混合情况。结果表明,最优导流板长度(3.6 m)明显改善了烟气的均匀性,促使入口处的压降下降100 Pa左右。涡旋混合器形成的小漩涡,增强了烟气和氨气的混合。最后对照不同流量下实验值和模拟值的压降变化,验证了多孔介质模型的可行性。模拟结果对设备的优化设计和实际运行具有指导作用。     

2株石油降解菌生长和降解石油条件的优化

对2株石油降解菌DH-5和DH-9生长的最适培养基成分以及降解石油的最佳环境条件进行了筛选。结果表明,DH-5的最佳培养基成分为ρ(原油)1 g.L-1、ρ(氮源)400 mg.L-1、ρ(磷源)200 mg.L-1、ρ(酵母浸出液)20 mg.L-1,最有效利用的氨基酸为精氨酸,最适环境条件为pH 7.0、盐度20、温度15～30℃;DH-9的最佳培养基成分为ρ(原油)1 g.L-1、ρ(氮源)400 mg.L-1、ρ(磷源)100 mg.L-1、ρ(酵母浸出液)20 mg.L-1,最有效利用的氨基酸为天冬氨酸,最适环境条件为pH 7.5、盐度20、温度30℃。当ρ(原油)为20 g.L-1时,DH-9的生物量和原油降解率分别是DH-5的2.58倍和2.29倍。研究表明,DH-9对高浓度原油的耐受性明显强于DH-5,而DH-5对低温的适应性优于DH-9,2个菌株对高盐度的适应性均较强。     

中小城市的光污染及防治对策

我国经济处于高速增长期,建设日新月异,中小城市的光污染问题日趋明显,防治显得十分重要。文章以中山市城区为例,对道路照明、建筑照明、广告照明、绿化照明,以及玻璃幕墙反射等光污染情况进行了调研和评价。根据中山市城区的光污染情况,从制定和完善光污染防治法规体系、加强规划和宏观管理、提高公众参与力度和监督力度、加大人才培养和政策扶持力度、加大清洁生产推广力度以及实施照明设计单位资质认证等多方面提出了对光污染的防治对策。     

钇覆盖Si@Al_（12）团簇的贮氢性能

利用密度泛函理论系统地研究了Y_mSi@Al_（12）（m=1—3）团簇及其贮氢性质.结果表明,在所研究的尺度范围内,钇原子未在Si@Al_（12）团簇上团聚;每个钇原子按18电子规则吸附氢分子,其中Y_3Si@Al_（12）团簇可以吸附16个完整氢分子,贮氢质量分数为5.0%,平均吸附能处于0.324—0.527 eV之间,较为理想的吸附能说明在室温条件下吸氢和脱氢是可行的.     

渗透性反应墙在地下水污染修复中的应用

渗透性反应墙技术是近年来比较流行的地下水污染原位处理方法。本文综述了渗透性反应墙技术的基本机理、主要结构类型、活性反应介质的选取原则及主要的反应介质,介绍了渗透性反应墙的工程实践应用及存在问题。