Concentrations,Cumulative Exposure and Critical Levels of Ozone in Ireland

Concentrations of tropospheric ozone(O₃) and exceedance of critical levels to vegetationhave been investigated and mapped for Ireland. Hourlyozone concentration data (1995–1997) at 7 sevenmonitoring stations and the CORINE landcover database,supported by a Geographical Information System, wereused. AOT40 (Accumulated exposure Over a Threshold of 40ppb) was calculated for daylight hours for each station,and mapped using surface interpolation. Average O₃concentrations vary from year to year, and were estimatedto be 28 ppb, 26 ppb and 24 ppb for 1995, 1996 and 1997respectively. Ozone concentrations show a large diurnalvariation, with a maximum in the afternoon and a minimumat night-time. The critical level for crops and (semi-)natural vegetation was exceeded in all years examined.The highest exceedance occurred in 1995, where thecritical level was exceeded for almost 35% of the mappedarea. Approximately 15% and 1% of the mapped area wasexposed to exceedance levels during 1996 and 1997respectively. The maximum cumulative exposures (AOT40)were approximately 5000, 3890 and 3230 ppbh in 1995, 1996and 1997 respectively. The critical level for forests wasnot exceeded during the period of investigation.     

A systems perspective of managing error recovery and tactical re-planning of operating teams in safety critical domains

Introduction

Research in human error has provided useful tools for designing procedures, training, and intelligent interfaces that trap errors at an early stage. However, this “error prevention” policy may not be entirely successful because human errors will inevitably occur. This requires that the error management process (e.g., detection, diagnosis and correction) must also be supported. Research has focused almost exclusively on error detection; little is known about error recovery, especially in the context of safety critical systems. The aim of this paper is to develop a research framework that integrates error recovery strategies employed by experienced practitioners in handling their own errors.

Method and Results

A control theoretic model of human performance was used to integrate error recovery strategies assembled from reviews of the literature, analyses of near misses from aviation and command & control domains, and observations of abnormal situations training at air traffic control facilities. The method of system dynamics has been used to analyze and compare error recovery strategies in terms of patterns of interaction, system affordances, and types of recovery plans. System dynamics offer a promising basis for studying the nature of error recovery management in the context of team interactions and system characteristics.

Impact on industry

The proposed taxonomy of error recovery strategies can help human factors and safety experts to develop resilient system designs and training solutions for managing human errors in unforeseen situations; it may also help incident investigators to explore why people's actions and assessments were not corrected at the time.     

基于人工蜂群算法的边坡最危险滑动面搜索

将用于连续数值优化问题的人工蜂群算法引入边坡稳定分析临界滑动面搜索领域.该方法模拟了蜂群的群体协作采蜜过程,具有自适应收敛的特点,克服了传统方法容易陷入局部最优的缺点,是一种全局优化算法.为进一步改善其在复杂边坡搜索中的效果,将Hooke-Jeeves模式搜索操作引入人工蜂群算法,提出一种用于边坡临界滑动面搜索的模式搜...     

注含氧氮气油藏产出气的爆炸极限与临界氧含量研究

西部某碳酸盐岩缝洞型油藏,在注入氮气的过程中,存在着氮气源内含有氧气的问题,这对油田的实际生产产生很大的安全威胁。为了研究该油藏注气的可行性,在室内进行了氮气不同含氧量条件下注入过程、生产过程以及处理过程中的安全性评估实验,得到不同含氧条件下注氮气驱的评价效果。研究表明:在高温高压油藏内部,氧气不会因分子质量较大等原因发生沉积;含氧氮气在油藏内部会与原油发生氧化反应,氧气含量越高,氧化反应越强;氧化产生的CO2对油藏的抽提作用明显,会使油藏流体变稠,气油比降低。文中用化学法和作图法对产出气体的临界氧含量作出简单确定,化学法确定临界氧含量为12%左右,作图法为16%,考虑到安全系数等因素,建议实际生产过程中氧气含量应低于8%。     

膜序批式间歇反应器的膜污染特性及控制

采取厌-好氧交替运行、实验室人工配水的方式,连续运行300 d,研究膜序批式间歇反应器运行过程的膜污染特性及其控制.结果表明,在运行初期的75 d内,污泥处于絮体状,SVI值64.6～110.6 　mL·g^-1,膜污染呈快速指数增长趋势,TMP平均增长速率为0.309　kPa·d^-1,膜阻力变化在0.393×10¹¹～1.298×10¹¹ m^-1·d^-1之间,比膜通量从4.4 　L·(m²·h·kPa)^-1下降为0.52 　L·(m²·h·kPa)^-1,75　d时的临界膜通量为20 　L·(m²·h)^-1.从75～120　d对系统进行了调控,反应器培养出好氧颗粒污泥,SVI值逐渐下降,从170　d开始,SVI一直保持在40 　mL·g^-1左右,污泥粒径逐渐增大,220　d时污泥粒径分布大多在500～1 000　μm.120～300　d运行过程中的膜污染呈缓慢增长趋势,TMP平均增长率仅为0.062 　kPa·d^-1,膜阻力变化率在0.291×10¹¹～0.404×10¹¹m^-1·d^-1,比膜通量从4.4 　L·(m²·h·kPa)^-1下降为1.4 　L·(m²·h·kPa)^-1,220 d时的临界膜通量为40 　L·(m²·h)^-1.这些数据表明好氧颗粒污泥的培养对减缓膜污染发生具有极大作用.曝气强度为100 m³·(m²·h)^-1时,比膜通量最大,曝气强度为69 m³·(m²·h)^-1时,膜污染速率最小.     

辽河保护区河道险工治理研究

通过对辽河干流河道险工全面考察、河道险工成因分析以及河道演变分析结果,分别采用马卡维耶夫法、平滩水位法、造床流量保证率法、主汛期月平均流量法对造床流量进行了计算;根据历年主槽平均宽法、经验公式法、造床流量下现状河道水面宽法的计算,同时充分考虑各河段河道特点、上下游协调统一,并为河道的演变发展预留一定空间,综合确定了辽河干流各河段整治宽度;分别针对辽河两岸岸坎-缓坡和陡坡,提出了河道险工综合治理技术,为辽河干流防洪工程体系提供技术支持。     

Guidelines for life extension process management in oil and gas facilities

Facilities life extension has caught the attention among the capital-intensive industries, like oil and gas. By extending the life cycle of the industrial assets, a wide range of benefits is obtained, comparing with other life ending management strategies. This article first contextualizes the implementation of the life extension concept in the oil and gas industry, showing global data about life extension. Despite the importance of the ageing process, due to its great economic impact and the risk it poses to the production sector, regulatory entities, even in countries more advanced in that sector or that have already experienced the extension process, developed only superficial material about the topic without defining a structured methodology for the assessment of the possibility of useful life extension. The available references do not allow a comprehensive analysis of that possibility, which highlights the importance the methodology proposed. Thus, this article proposes a guideline for the life extension process management, strengthening a framework containing the main evaluation stages, aiming to facilitate the analysis of issues related to ageing and to support the decision-making process. Lastly, real case studies regarding current life extension processes submitted to the Brazilian regulatory body were evaluated against the proposed framework stages, evidencing their lack of necessary details to support the decision-making. Upon the realization that the real cases identified do not allow for the assessment of the contribution and adequacy of the proposed framework in its entirety, the same was also applied to a hypothetical case. The latter was developed based on facts reported by a major operator in Brazil. The result was the determination that the use of the proposed methodology transformed the assessment of the possibility of life extension into a systematic and transparent process, leading to easier and better-founded decision-making procedures, and improving the management of the asset during its extended life.     

Altitudinal Distribution of Meltwater and Its Effects on Glacio‐Hydrology in Glacierized Catchments,Central Asia

In glacierized catchments, elevation is correlated with meltwater through its association with temperature, precipitation, and glacier hypsometry. The revelation of the altitudinal distribution of meltwater, unattended and not fully understood in previous work, might provide a better understanding of climate change impacts on glacio‐hydrology. Here, critical zone approach was defined and applied in 12 glacierized catchments of the Tien Shan–Pamir–Karakorum Mountains, Central Asia using manually calibrated glacier‐enhanced Soil and Water Assessment Tool model over 1966–2005. The critical zone, a sequence of elevation bands with above‐average snow and glacier melt, contributes maximum meltwater to total runoff. The critical zone shared 37%–95% (average = 80%) of meltwater contributions to total runoff, although its size was only 13%–30% of the total elevational relief. The critical zone controlled 76% and 82% variability in relative changes of glacier area and total runoff at the catchment scale, respectively. The increase in temperature was identified as the dominant driver for variations in total runoff in all catchments except Vakhsh and Yurungkash, where precipitation change remained dominant. Overall, glacier hypsometry limited the first‐order control of meltwater distributions on glacio‐hydrology. It is concluded that critical zone approach can interpret the proxy role of elevation to affect water availability under climate and glacier area change in glacierized catchments.     

“Ethereal Carbon”: legitimizing liquefied natural gas in British Columbia

ABSTRACT

This paper examines the provincial government of British Columbia's recent proposal of building a Liquefied Natural Gas (LNG) industry, in which natural gas extracted through hydraulic fracturing will be liquefied and then exported to Asian markets. Drawing upon the growing literature on energopower, petro-state, and petro-culture, selected texts and images from “LNG in BC”—the project's official branding website—were analyzed through a multimodal critical discourse analysis. The results reveal two primary strategies of legitimation: the first emphasizes the economic benefits of LNG development in terms of employment and taxation revenues; the second defines LNG as a means of strengthening B.C.’s environmental leadership. The second narrative depends heavily upon the symbolic values of natural gas, contrasting its “clean” appearance (as a colorless and odorless gas) with the material density and “toxic sensuality” of other “dirty” fossil fuels (such as coal, oil, and bitumen). The website also presents a linear and simplified “storyline” of the generation of LNG which emphasizes the simple, “clean” process of liquefaction to distract attention from the ecological and health risks of hydraulic fracturing.