Fuzzy logic approach to calculation of thermal hazard distances in process industries

In this paper, a general procedure to deal with uncertainties in each stage of consequence modeling is presented. In the first part of the procedure, the sources of uncertainty are identified and confirmed by sensitivity analysis for the source term, dispersion, physical effects and consequence analysis. While the second part comprises an application of the fuzzy logic system to each step of the consequence modeling. The proposed procedure is verified by the case study for a pool fire liquefied natural gas (LNG) on water. The results in terms of thermal radiation distances are compared with calculations obtained using the Monte Carlo method and with experimental data. The consequence model based on fuzzy logic approach provides less uncertain and more precise results in comparison to the deterministic consequence model.     

森林凋落物研究现状及我国西南喀斯特地区研究展望

近几十年来,我国西南喀斯特地区生态环境退化严重,石漠化面积迅速扩大,林地覆盖率急剧下降,成为制约我国西部大开发生态建设中不可回避的重要科学问题,严重影响了西南地区社会、经济的可持续发展。喀斯特地区土层薄且侵蚀严重,土壤中的有机碳和营养盐主要来自地表枯枝落叶层的分解及累积。在气候变暖、陆地生态系统土壤温度升高、土壤有机碳急速流失和土壤质量退化的背景下,分析不同林下凋落物量和降解动态以及土壤有机碳库积累差异,揭示西南喀斯特地区不同林地凋落物归还量及其对土壤碳库积累的贡献具有极其重要的意义,将为喀斯特地区林地恢复重建和石漠化遏制工作提供科研依据。     

垃圾焚烧厂渗滤液处理工程中常见问题探讨

结合在渗滤液处理设计上的经验,对垃圾焚烧厂渗滤液处理工程中出现的一些问题进行分析和探讨,希望本文能起到抛砖引玉的作用。     

Influence of welding speed and power on residual stress during gas tungsten arc welding (GTAW) of thin sections with constant heat input: A study using numerical simulation and experimental validation

The temperature distribution and residual stresses for a GTAW circumferential butt joint of AISI 304 stainless steel using numerical simulation have been evaluated. For evaluation of weld induced residual stresses, the analysis of heat source fitting was carried out with heat inputs ranging from 200 to 500 J/mm to arrive at optimal heat input for obtaining proper weld penetration and heat affected zone (HAZ). For this chosen heat input, the influence of different weld speeds and powers on the temperature distribution and the residual stresses is studied. The heat source analysis revealed the best choice of heat input as 300 J/mm. The residual stresses on the inner and outer surfaces, and along the radial direction were computed. Increase in temperature distribution as well as longitudinal and circumferential residual stresses was observed with the increase in weld speed and power. The validity of the results obtained from numerical simulation is demonstrated with full scale shop floor welding experiments.     

复合人工湿地系统强化处理单元的运行特性与效果

针对目前人工湿地运行中的水流分布不均、易堵塞、溶解氧不足导致NH4+-N硝化不充分及除磷率低下等问题,研究了作为复合人工湿地系统组成要素的高负荷水解酸化池、自然复氧/沉淀一体化装置、强化除磷脱氮槽等强化处理单元的运行特性及对全系统处理效果的影响.结果表明,高负荷水解酸化池对COD、SS有较强的去除作用,分别占系统总去除率的38.05%和34.82%;一体化装置对SS的去除占系统总去除率的22.01%,并使DO提高到2.5 mg·L-1以上;经两段强化除磷脱氮槽的强化处理,TP综合去除率提高8%以上,并使湿地出水各类污染物全面达到GB 18918-2002一级A标准.     

长期秸秆还田褐土有机碳矿化特征及其驱动力

基于连续30 a(1992～2021年)秸秆还田长期定位试验,按照等碳量秸秆还田,设置秸秆覆盖还田(SM)、秸秆粉碎直接还田(SC)、秸秆过腹还田(CM)和秸秆不还田(CK)这4个处理,探讨长期不同秸秆还田方式对土壤有机碳、土壤活性有机碳组分、土壤碳库管理指数、酶活性和土壤有机碳矿化的影响,揭示春玉米连作体系褐土有机碳矿化特征及其主要驱动因子,为褐土区秸秆还田措施优化和固碳减排等提供科学依据.结果表明:①秸秆还田处理均提高了褐土土壤有机碳含量,CM处理提高幅度最大,且碳库管理指数提升效果最显著.②SC和CM处理的活性碳组分含量均上升,而SM处理的易氧化有机碳含量显著降低.③温度每升高10℃,矿化速率约提升7.99 mg·(kg·d)-1.不同秸秆还田处理土壤有机碳矿化速率顺序为:CM＞SC＞SM＞CK.④低温(15～25℃)条件下,CM处理的温度敏感性最低,最有利于碳库的积累,能有效提高土壤有机碳库周转速率,缩短周转时间,可作为褐土管理的最佳秸秆还田模式.⑤温度、土壤中β-1,4-葡萄糖苷酶活性和DOC是褐土土壤有机碳矿化的主要驱动力.有机碳组分和温度可以通过影响土壤酶活性,进而影响土壤有机碳的矿化.