A hybrid model for human factor analysis in process accidents: FBN-HFACS

Human factors are the largest contributing factors to unsafe operation of the chemical process systems. Conventional methods of human factor assessment are often static, unable to deal with data and model uncertainty, and to consider independencies among failure modes. To overcome the above limitations, this paper presents a hybrid dynamic human factor model considering Human Factor Analysis and Classification System (HFACS), intuitionistic fuzzy set theory, and Bayesian network. The model is tested on accident scenarios which have occurred in a hot tapping operation of a natural gas pipeline. The results demonstrate that poor occupational safety training, failure to implement risk management principles, and ignoring reporting unsafe conditions were the factors that contributed most failures causing accident. The potential risk-based safety measures for preventing similar accidents are discussed. The application of the model confirms its robustness in estimating impact rate (degree) of human factor induced failures, consideration of the conditional dependency, and a dynamic and flexible modelling structure.     

Density functional theory (DFT) studies of vanadium-titanium based selective catalytic reduction (SCR) catalysts

Based on density functional theory (DFT) and basic structure models, the chemical reactions on the surface of vanadium-titanium based selective catalytic reduction (SCR) denitrification catalysts were summarized. Reasonable structural models (non-periodic and periodic structural models) are the basis of density functional calculations. A periodic structure model was more appropriate to represent the catalyst surface, and its theoretical calculation results were more comparable with the experimental results than a non-periodic model. It is generally believed that the SCR mechanism where NH₃ and NO react to produce N₂ and H₂O follows an Eley-Rideal type mechanism. NH₂NO was found to be an important intermediate in the SCR reaction, with multiple production routes. Simultaneously, the effects of H₂O, SO₂ and metal on SCR catalysts were also summarized.     

基于SVR的长江经济带水环境承载力评价

基于DPSIRM模型构建区域水环境承载力评价指标体系,并基于SVR模型构建了区域水环境承载力评价模型,利用交叉验证法对SVR模型参数进行优化选择,进一步提高模型预测精度.运用该模型研究了长江经济带2009~2018年的水环境承载力演变趋势及空间差异,结果表明：长江经济带水环境承载力等级整体呈现升高趋势,其中上游城市群承载等级由II级（超载）提升到了IV级（弱可承载）;中游城市群承载等级由II级（超载）提升到了IV级（弱可承载）;下游长三角区域承载等级由I级（重超载）提升到了IV级（弱可承载）.将评价结果与熵权-TOPSIS法的评价结果相比较,相同率达到91.7%,说明SVR模型评价区域水环境承载力可行,评价结果可靠.以下游区域为例,分别对其6个子系统的承载力进行剖析,并运用单因素轮换OAT法对各子系统内的评价指标进行敏感性分析,便于决策者识别指标敏感性.     

ASM1中废水和污泥组分浓度的测定方法研究

对呼吸计量法应用于校准ASM1作了简明的阐述。在呼吸速率与模型组分关系的基础上,介绍了ASM1中废水与污泥各组分浓度的测定方法,并指出模型组分细化的意义。     

清洁生产工艺在造纸工业中的应用

介绍了清洁生产这个新概念,清洁生产工艺在造纸工业中的应用,实例表明:造纸废水再循环,不准能节约水资源,节约能源,防止环境污染,而且可以取得良好的经济效益和社会效益,为造纸废水在2000 年前达到国家排准排放奠定了良好基础     

SBR工艺处理城市垃圾渗滤液的可行性分析

在参考国内外垃圾渗滤液的处理方案后，选择厌氧预处理 SBR工艺作为处理方案，通过实验对该废水处理的情况来看，该工艺较好地适应了垃圾渗滤液的处理特点，能达到比较良好的效果。     

托盘式烟气脱硫喷淋塔空塔冷态流场数值模拟

以600MW机组多孔合金托盘喷淋塔为研究对象,利用国际流行的商用CFD(ComputationalFluidDynamics)软件Fluent及其前处理软件Gambit对烟气脱硫立式喷淋空塔的流场进行二维数值模拟。计算中选用模型作为计算模型,用SIMPLE算法进行计算。计算结果表明,喷淋塔的烟气入口角度以及多孔合金托盘的安装高度对塔内流场分布有一定的影响,安装托盘后气速明显均匀化,斜切式烟气进口流场分布较直进式均匀,还获得了合适的托盘安装高度。     

金陵石化炼油厂第二污水处理场改造工程介绍

金陵石化炼油厂第二污水处理场改造工程中对原有处理设施进行了工艺调整和优化，采用了均质，二级好氧生物处理及后浮选工艺，工程运行结果表明所采用的技术、设备是合理有效的。     

化学强化一级处理系统BP神经网络建模研究

运用实验室得到的数据为样本，选取了CODcr和絮凝剂投加量为指标，采用三层结构的神经网络，利用Matlab的神经网络工具箱中的批处理梯度下降法对CEPT系统进行辩识。辩识结果表明：模型的预测值与实测值的平均误差在3．7％左右，具有较高的精度。同时，该模型还具有适应性强，使用方便，高效的特点，为CEPT系统的在线实时控制提供了一条有效的途径。     

活性污泥外循环SBR系统循环污泥释磷能力研究

本试验以HAc作为厌氧释磷的碳源有机物，以SBR系统外循环污泥作为研究对象，探索外循环活性污泥的厌氧释磷能力和获取高浓度富磷污水的途径，试验表明：厌氧过程中聚磷菌吸收HAc和释放PO4^3 的分子比为1：1。即吸收2．06mgHAc-COD将诱导1mgP释放，单位时段比污泥的平均释磷速率Vp=6.54.t^0.76，理想的厌氧时间为60－180min，减少循环污泥释磷系统的反应容积可以提高富磷污水磷酸盐的浓度。