淬火硝盐的劣化和再生

使用扫描电镜及能谱分析、化学分析方法,全面分析了使用硝盐浴进行分级淬火和等温淬火时,淬火硝盐劣化产物。结果表明:硝盐反应生成物(Na₂CO₃、NaOH),设备(主要是盐槽、盐泵、管道)、夹具、料盘及工件等氧化产物(FeO·Fe₂O₃·Fe₃O₄),外来物(灰尘,炭黑)是造成硝盐劣化的主要原因。据此,提出了预防淬火硝盐劣化措施:选用品质好的基盐;选用热稳定性较高的混合盐;保持淬火盐浴温度均匀,淬火前后温升可控,尽量避免“瞬间”过热使用;尽量避免外来杂质进入;做好日常维护。并简要介绍了淬火硝盐再生处理方法。     

Seismic life-cycle cost analysis of ageing highway bridges under chloride exposure conditions: modelling and recommendations

Chloride-induced corrosion of highway bridges constitutes a critical form of environmental deterioration and may result in significant escalation of seismic life-cycle costs due to increased fragility during earthquake events. Most of existing literature tends to adopt simplistic uniform area loss assumptions in lieu of potentially complex, yet realistic and more detrimental, pitting corrosion models for seismic vulnerability analysis. Since the degree of deterioration depends on the severity and duration of exposure, there exists a need to investigate the influence of uniform vs. pitting corrosion assumption on seismic life-cycle costs for varied chloride exposure conditions. A case-study example of a highway bridge in Central and Southeastern US reveals consideration of pitting corrosion as critical for extreme exposures compared to relatively minor settings. Subsequently this study provides recommendations to aid bridge engineers and stakeholders to balance between computational cost and accuracy of results to aid prompt decisions on rehabilitation of ageing bridges in different exposure conditions. A framework is also included to compute seismic life-cycle costs from generic measures of corrosion, independent of assumed exposure scenario. This framework is particularly helpful for seismic loss assessment of highway bridges in chloride exposure zones with periodic field measurements to estimate the extent of structural deterioration.     

Characterisation of moisture migration of shiitake mushroom (Lentinula edodes) during storage and its relationship to quality deterioration

Water is a critical factor influencing the quality of mushrooms. This paper investigated the moisture migration of shiitake mushroom during storage using low-field nuclear magnetic resonance (LF-NMR) and magnetic resonance imaging (MRI) and its relationship to quality deterioration. Three water components assigned as water in different cell compartments of cell wall, cytoplasm and vacuole were observed in shiitake mushroom matrix. As the prolonging of storage time, the right shift of immobilised water and left shift of free water led to the merge of these two peaks at the end of storage. The increase in peak area of water in cytoplasm and decrease in the peak area of water in vacuole indicated evident moisture migration from vacuole to cytoplasm. MRI images showed heterogeneous water distribution in shiitake mushroom, and the water migrated from centre to surface, then evaporated to the environment. Besides, the moisture migration might be related to the weight loss and textural softening of shiitake mushroom.     

工艺物料泄漏对循环冷却水系统的影响及应对措施

某石油化工企业循环冷却水系统出现较为严重的水质恶化现象,通过对装置进出口的循环冷却水水质进行分析,判定水质恶化是因裂解新区丙烯精馏单元冷却器EA-475发生工艺物料泄漏所致。在冷却器无条件停工彻底堵漏的情况下,针对泄漏工艺介质的特性,采取了循环冷却水排污置换,加大缓蚀阻垢剂和杀菌剂的投加量,更换杀菌剂种类,对系统进行粘泥剥离等一系列应对措施。应对措施的实施结果表明,循环冷却水中的异养菌和生物粘泥得到了有效控制,金属腐蚀速率和污垢沉积速率达到了要求,避免了水质恶化对生产装置造成进一步的影响。     

废润滑油脱色技术研究及应用进展

根据国内外废润滑油脱色技术的研究和应用情况,分析了废润滑油劣化成色机理,对以吸附法、加氢法、絮凝脱色法为主的废润滑油脱色技术进行了分析总结。从各类废润滑油脱色技术的脱色原理出发,结合具体的废润滑油脱色应用,评述了相关的废润滑油脱色技术的脱色效率、应用进展和存在的问题,并指出了废润滑油脱色技术需要进一步研究的问题和发展的方向。     

Life cycle performance goals for civil infrastructure: intergenerational risk-informed decisions

Civil infrastructure facilities play a central role in the economic, social and political health of modern society. Such facilities are susceptible to ageing, which is stochastic in nature and makes their reliabilities time dependent. Life-cycle engineering analysis and risk-informed decision tools have advanced in recent years for managing public investments in performance assurance and risk mitigation of civil infrastructure. However, certain civil infrastructure projects may be designed for service periods that are substantially longer than what has been typically expected of buildings, bridges and similar facilities, extending the potential consequences of life-cycle engineering decisions far beyond the limits for which there is practical experience. Current assessment procedures will require modification to evaluate performance of civil infrastructure facilities over extended time frames and to support sustainable and equitable decisions affecting long-term public safety. This paper considers a number of key issues that must be addressed in life-cycle reliability assessment of civil infrastructure facilities that must remain functional for service periods of several generations, and introduces perspectives on risk that are germane to ensure sustainability and intergenerational equity in risk-informed decision-making.     

水泥基材料的碳硫硅钙石型硫酸盐侵蚀(TSA)

主要介绍了近年来国外关于TSA的研究情况和一些报道的工程实例,分析了TSA发生与发展的影响因素.     

混凝土耐久性破坏经时模型--模型计算及服役年限的预测

本文在前文提出的CDFT Model基础上，探讨了利用CDFT Model对混凝土工程的服股年限进行预测的方法，并对实际工程巴林第二跨海公路桥的服役年限进行了预测，结论认为其服役年限满足设计要求。