Post‐Ike economic resilience along the Texas coast

The economic devastation resulting from recent natural disasters has spawned intense interest in programmes that promote regional resilience. The economic impacts of Hurricane Ike (September 2008) endured long beyond the storm's landfall, compounded by a national recession. This study analyses the pattern of post‐Ike industrial growth in eight coastal counties of Texas, United States, and identifies sources of resilience and potential drivers of recovery. The results indicate that post‐disaster growth patterns differ from established growth patterns. Levels of resilience vary across industrial sectors, and service sectors tend to lead a recovery. The resilience of the hotel and restaurant sector, for instance, suggests that the presence of relief workers might immunise certain sectors against a post‐disaster economic downturn. Besides the sectors that are generally resilient, each county has its own distinct sectors that, depending on the extent of the damage suffered, tend to perform strongly after a disaster, owing to the characteristics of the respective county's economy.     

Measuring disaster recovery: bouncing back or reaching the counterfactual state?

How should one measure the recovery of a locale from a disaster? The measurement is crucial from a public policy and administration standpoint to determine which places should receive disaster assistance, and it affects the performance evaluation of disaster recovery programmes. This paper compares two approaches to measuring recovery: (i) bouncing back to pre‐disaster conditions; and (ii) attaining the counterfactual state. The former centres on returning to normalcy following disaster‐induced losses, whereas the latter focuses on attaining the state, using quasi‐experimental design, which would have existed if the disaster had not occurred. Both are employed here to assess two housing recovery indicators (total new units and their valuations) in Hurricane Katrina‐affected counties (rural and urban). The examination reveals significantly different outcomes for the two approaches: counties have not returned to their pre‐disaster housing conditions, but they do exhibit counterfactual recovery. Moreover, rural counties may not be as vulnerable as assumed in the disaster recovery literature.     

Analysis and assessment of the Qingdao crude oil vapor explosion accident: Lessons learnt

A devastating crude oil vapor explosion accident, which killed 62 people and injured 136, occurred on November 22, 2013. It was one of the most disastrous vapor cloud explosion accidents that happened in Qingdao's storm drains in China. It was noted that blast overpressure and flying debris were the main causes of human deaths, personal injuries and structure damages. Two months after the accident, it was reported that there were three contentious issues in the investigation report. First issue was the discrepancy between the temperature of the crude oil vapor explosive limits which were measured by the investigation panel and the temperature reported by the local fire department. Second issue was the contradiction between the upper explosive limit and vapor pressure of the crude oil vapor. The last issue was the location of the ignition source which led to the explosion.In the present study some specific features of this accident and various causes led to the explosion, high casualties and severe damages were analyzed. Three contentious issues in the official investigation report were investigated and tested in detail. The first element tested was the explosive limits and limiting oxygen concentration of the crude oil vapor at different temperatures. Based on theoretical analysis and field investigations, the last two elements in the report were analyzed from multiple perspectives. Based on the TNO Multi-Energy model and PROBIT equations, damage probability of affected people at the leaking site was also estimated. The investigation concluded with a result that precautions need to be taken to prevent flammable gas explosions in the drainage systems. Key steps were explicitly discussed for improving the hazard identification and risk assessment of similar accidents in the future.     

Paired assistance policy and recovery from the 2008 Wenchuan earthquake: a network perspective

The role of the paired assistance policy (PAP) in facilitating recovery after the Wenchuan earthquake in China on 12 May 2008 is best analysed from a network perspective. This paper makes five assumptions to explore the relationship, and then draws on three additional cases to examine them. The key findings support all five assumptions. First, the interactions of authority compliance initiated the PAP, and second, the interactions of resource input significantly contributed to rapid reconstruction following the earthquake. Third, the interactions of knowledge transfer supported social system recovery, and fourth, the interactions of benefit reciprocity laid the foundation for sustainable recovery. Fifth, by contrast, the interactions of performance comparison caused suboptimal overfunding of particular public infrastructure projects and reduced local self‐reliance to some extent. Finally, suggestions are made to improve the policy implications of extending the use of the PAP in other administrative contexts. The PAP could become an even more important policy device in the future.     

基于灾后恢复过程解析的城市韧性评价体系

为实现对城市韧性的有效评价,本论文在系统研究国际城市韧性评价体系的基础之上,结合中国城市发展的现状,基于对城市灾后实际恢复过程的系统考察,建立了基于恢复过程的城市韧性评价体系。该评价体系通过解析城市灾后恢复过程的四个阶段:救援阶段(Rescue)、避难阶段(Refuge)、重建阶段(Rebuild)、复兴阶段(Revival),从社区与人口(Community and Population)、政府与管理(Official Organization and Management)、住房与设施(Valuable Housing and Facilities)、经济与发展(Economy and Development)、环境与文化(Renewable Environment and Culture)共五个维度,以62项指标对城市的韧性进行系统分析。这一体系可以简称为城市韧性评价的ReCOVER体系,其中“Re”代表了城市恢复的四个阶段,COVER则分别代表了城市韧性的五个维度。进而以该体系为基础,对我国大陆31个省级行政区域的城市韧性进行了五个维度、四个阶段的实证研究,并对城市韧性的提升策略,给出了分析建议。     

机动车加油过程中气液两相流动特性的CFD数值模拟

随着环保法规的不断完善,机动车加油过程中所产生的油气排放污染问题越来越受到重视.国外自20世纪90年代中后期开始采用数值模拟手段对机动车的加油过程进行研究,而国内迄今尚处于空白阶段.对机动车加油过程所涉及的＂加油枪喷嘴＋加油管＋油箱＋回气管＂物理体系进行适当简化,采用商业计算流体动力学（CFD）软件Fluent中提供的VOF气液两相流模型和RNG k-ε湍流模型,在基于Gambit软件确定网格划分方案和进行适当的边界条件设置后,建立了合理可行的加油过程气液两相流动CFD数值模拟模型,讨论了加油速度对油箱内气相空间静压力的影响,揭示了汽油在加油管内的回流现象.结果表明,加油枪的流量越大,油箱内气相空间的静压总体上也逐渐增大;同时油箱内气相空间的静压总体上可以划分为3个较为明显的阶段.而当加油流量较大时,往往会引起汽油在加油管油帽段内回流,从而使得加油枪过早跳枪.本研究为国内自主开展机动车加油以及油气排放污染控制技术和设备方面的研究开发奠定了一定基础.     

pH modeling for maximum dissolved organic matter removal by enhanced coagulation

Correlations between raw water characteristics and pH after enhanced coagulation to maximize dissolved organic matter (DOM) removal using four typical coagulants (FeCl₃, Al₂(SO₄)₃, polyaluminum chloride (PACl) and high performance polyaluminum chloride (HPAC)) without pH control were investigated. These correlations were analyzed on the basis of the raw water quality and the chemical and physical fractionations of DOM of thirteen Chinese source waters over three seasons. It was found that the final pH after enhanced coagulation for each of the four coagulants was influenced by the content of removable DOM (i.e. hydrophobic and higher apparent molecular weight (AMW) DOM), the alkalinity and the initial pH of raw water. A set of feed-forward semi-empirical models relating the final pH after enhanced coagulation for each of the four coagulants with the raw water characteristics were developed and optimized based on correlation analysis. The established models were preliminarily validated for prediction purposes, and it was found that the deviation between the predicted data and actual data was low. This result demonstrated the potential for the application of these models in practical operation of drinking water treatment plants.     

投加化学药剂改善城市黑臭河流水质的研究

该研究通过投加化学药剂比选、药剂投加浓度和投加方式优化试验,考察了投加化学药剂对城市黑臭河流水质的改善效果和适用性。结果表明,投加过氧化钙能够快速提高水体溶解氧含量,同时降低水体总磷含量。在该试验条件下,投加400 mg/L的过氧化钙后水中的溶解氧迅速升高,但1天后即恢复到投加前水平。由于投加过氧化钙增氧的成本相对较高,并且水体流动性会影响过氧化钙的增氧效果,投加过氧化钙方法仅适用于对封闭的污染水体进行快速增氧和修复。     

Integrating flare gas with cogeneration systems: Operational risk assessment

Flare gas utilization in a cogeneration plant is an attractive proposition considering its environmental and economic incentives. Evaluation of the operational risk of integrating flare gas with cogeneration is complex due to the uncertainty in flare gas quality and process conditions. The current study delves into the change in operational risk after modifying the existing cogeneration process with the addition of fuel from flare gas. Based on the process hazards evaluation, the current study identified two critical loss control events (or top events) - boiler gas temperature exceeding operating design temperature and rich fuel mixture in the boiler firebox. The underlying causes that may contribute and lead to these loss control events were identified using fault trees and were updated to the existing cogeneration scenarios. Similarly, different consequential events that may arise from the loss control events were analysed using event trees with existing system safeguards. A Bayesian network model with its explanatory power mapped all the identified dangerous scenarios from the fault trees and event trees to predict integrated systems reliability and diagnose causal factors. Bayesian Network analysis illustrates the dynamic cause-effect relationship and determines the risk escalation due to the changes in the composition of flare gas that is fed to the boiler. The presence of a higher percentage of hydrogen (above 40 mol%) in the flare gas escalates the risk of lean air to fuel ratio in the boiler firebox and increases boiler radiation zone duty. These conditions are detrimental to the boiler firebox operation and can result in critical scenarios such as flame impingement and tube rupture. Additionally, other consequences-a steam explosion and boiler stack explosion were also investigated. However, their probability of occurrence was relatively insignificant with the given frequency of flare gas utilization in the cogeneration system.     

区域轨道交通系统节点重要度及故障恢复研究

为提高区域轨道交通系统(RRTS)正常运营下的可靠性和故障情况下的弹性,分析区域轨道交通网络(RRTN)的拓扑特性,构建拓扑结构弹性评价模型,实现突发条件下系统弹性的定量评价;提出一种基于系统弹性的结构评价方法,根据节点重要度评价,识别出系统关键节点;应用弹性损失三角形,进行多种故障情况下系统最优恢复策略研究。结果表明:RRTN在Space L模型下具有无标度网络特性;系统弹性分析结合科普兰评分法,可以提高RRTS节点重要度评价的准确性;最优故障恢复策略从全局角度寻求不同恢复策略下系统弹性的最大值,优化了RRTS结构弹性和系统恢复能力。