Pavement Flooding Risk Assessment and Management in the Changing Climate

Flooding, which can cause substantial infrastructure damages resulting in adverse social, environmental, and economical consequences, is a rising concern in the changing climate. Road networks consisting of interconnected links designed to accommodate transportation needs of the public and can be affected by flood hazards. In road pavement design and management, historical climate design data are becoming less representative of the future climate resulting in unexpected risks. Road pavement damage caused by expected intensification of flood events under climate change can lead to safety, mobility, comfort, functionality, and accessibility concerns. In order to mitigate the risk of flooding on pavements, this research develops risk quantification methodology and implementation guidelines, which enable informed pavement management and adaptation leading to increased resilience of pavement networks in the changing climate. The risk assessment methodology includes project level risk assessment and network level risk assessment. The key components of project level risk assessment include flood hazard assessment, flooded pavement performance analysis, quantification of pavement fragility, and consequence analysis. The network level risk assessment is an extension of the project level risk assessment. It involves an eight-step approach including mapping the flood hazards, mapping the road exposure and characteristics, matching fragility models, calculating risk for a range of events, and summing up the risks. The risk estimation can be used to inform and initiate the adaptation planning and programming at the prioritized sections of pavement networks. Case studies have been conducted to illustrate the implementation of the risk assessment methodology. Based on the research findings, pavement flooding risk assessment and management implementation guidelines and procedures are developed. The outcome of the research helps the advancement of pavement design and management practices for addressing flood hazards. The results in the flood hazard analysis indicate that the probabilistic flood hazard analysis method provides a quantitative estimation of flood hazard for various climate change scenarios. Road pavement infrastructure can be subjected to more frequent and intense extreme precipitation events causing more pavement flooding in the case study area. The new extremes should be incorporated in pavement design and management practices. Regarding pavement damage, a comprehensive analysis summarizes the pavement damage processes, causes, components, damage patterns, impact factors, and temporal and spatial characteristics. Probabilistic pavement flooding damage analysis is illustrated by fragility models, which provide estimations of conditional probability of exceeding certain pavement damage given a flood event. Pavement mechanistic-empirical (ME) design method is utilized to simulate the impact of extreme precipitations on pavement performance of typical arterial and collector flexible pavements in Toronto, Canada. Fragility models and curves are generated based on the performance simulation results. In the case study, the pavement roughness degradation is accelerated post-flooding during the life cycle, which is assessed as the jump & delayed effect damage pattern. The extreme events can lead to the loss of pavement life up to 303 days, approximately more than 4% of a pavement’s life. More flood cycles lead to shorter pavement life, which is caused by the accelerated deterioration after the flood cycles. The increase of precipitation levels under climate change increases the probability of pavement damage in each damage state for different designs. The incorporation of ME performance simulation and experimental testing allows obtaining the damage data from aged pavements for fragility analysis. The quantitative pavement flooding risk assessment at the project level integrates the findings of the flood hazard analysis, fragility, and vulnerability. Considering the climate from 2017 to 2100, the extreme precipitations from representative concentration pathway (RCP) 8.5 climate scenario results in asset value losses as high as CAD$112,471 and CAD$46,487 per kilometer for arterial and collector pavements, respectively for moderate damage. The risk of major damage is not the highest when compared to the risks of minor and moderate damage, which is because the major damage has a lower occurrence resulting in lower asset value losses in the case study. The network spatial risks are analyzed and visualized through risk mapping. The results indicate the length of flooded pavements for each functional class increases as the magnitude of flooding increases. As the damage state threshold value increases, the percentage of road sections with high risk decreases and that with low risk increases. The risk of climate-change-induced flooding is sensitive to the range of flood events included in the risk assessment. When include the climate change scenario in a full range of flood hazard, the percentage of road network with low risk is increased from 12.1% to 45.7%, and the percentage of high-risk sections is increased from 46.0% to 79.9% for pavement damage over 1.5%. Adaptation strategies that have been established are reducing hazard exposure, reducing fragility of pavement structures, and reducing the cost of certain damage. The implementation guidelines are introduced according to the time horizon: pre-event, during-event, and post-event. Pre-event, probabilistic risk assessment and risk matrix approach are both included in the risk assessment guide. The general principles, key activities, and procedures introduced in the guide enable researchers, practitioners, and stakeholders to apply the research findings

An Improved Focused Crawler: Using Web Page Classification and Link Priority Evaluation

A focused crawler is topic-specific and aims selectively to collect web pages that are relevant to a given topic from the Internet. However, the performance of the current focused crawling can easily suffer the impact of the environments of web pages and multiple topic web pages. In the crawling process, a highly relevant region may be ignored owing to the low overall relevance of that page, and anchor text or link-context may misguide crawlers. In order to solve these problems, this paper proposes a new focused crawler. First, we build a web page classifier based on improved term weighting approach (ITFIDF), in order to gain highly relevant web pages. In addition, this paper introduces an evaluation approach of the link, link priority evaluation (LPE), which combines web page content block partition algorithm and the strategy of joint feature evaluation (JFE), to better judge the relevance between URLs on the web page and the given topic. The experimental results demonstrate that the classifier using ITFIDF outperforms TFIDF, and our focused crawler is superior to other focused crawlers based on breadth-first, best-first, anchor text only, link-context only, and content block partition in terms of harvest rate and target recall. In conclusion, our methods are significant and effective for focused crawler

A combined method for gas-bearing layer identification in a complex sandstone reservoir

Langgu Depression is a mature oil and gas exploration area with complicated lithological and physical properties. The varying formation fluid, low-resistivity hydrocarbon-bearing reservoirs, and non-uniform logging series greatly increase the difficulty of gas reservoir identification. The Monte Carlo method is employed to simulate the neutron–gamma logging responses to gas saturation and the influential factors. According to the result, a new gas identification chart eliminating the influence of porosity and formation water salinity is proposed to identify gas reservoirs in the old wells. At the same time, a fluid factor extracted from array acoustic logging and core measurement data is sensitive to the development of gas-bearing layers and useful for the identification of gas reservoirs in the new wells with array acoustic logging. The field examples show that the new combined method greatly improves the ability to identify gas-bearing layers and works well in old well reexamination and new well interpretation

The impact of bank merger growth on CEO compensation

We examine the impact of bank mergers on chief executive officer (CEO) compensation during the period 1992–2014, a period characterised by significant banking consolidation. We show that CEO compensation is positively related to both merger growth and non-merger internal growth, with the former relationship being higher in magnitude. While CEO pay–risk sensitivity is not significantly related to merger growth, CEO pay–performance sensitivity is negatively and significantly related to merger growth. Collectively, our results suggest that, through bank mergers, CEOs can earn higher compensation and decouple personal wealth from bank performance. Furthermore, we document a more severe agency problem in CEO compensation as a consequence of bank mergers relative to mergers in industrial firms. Finally, we find that the post-financial crisis regulatory reform of executive compensation in banks has limited effectiveness in curbing the merger–pay links

Amidine-Mediated Zwitterionic Ring-Opening Polymerization of N-Alkyl N-Carboxyanhydride: Mechanism, Kinetics, and Architecture Elucidation

© 2016 American Chemical Society. Zwitterionic ring-opening polymerization (ZROP) of N-butyl N-carboxyanhydrides (Bu-NCAs) has been investigated using 1,8-diazabicycloundec-7-ene (DBU), a bicyclic amidine initiator. It was found that poly(N-butylglycine)s (PNBGs) with molecular weight (Mn) in the 3.5-32.4 kg mol-1 range and polydispersity index (PDI) in the 1.02-1.12 range can be readily obtained by systematically varying the initial monomer to initiator feed ratio. The polymerization exhibits characteristics of a controlled polymerization, as evidenced by the linear increase of polymer molecular weight with conversion and the successful enchainment experiments. Kinetic studies revealed that the reaction is first-order dependent on the monomer and the DBU concentration. The rate of initiation is comparable to that of the propagation. Random copolypeptoids of poly[(N-propargylglycine)-r-(N-butylglycine)]s [P(NPgG-r-NBG)s] were also synthesized by DBU-mediated copolymerization of Bu-NCA and N-propargyl N-carboxyanhydride (Pg-NCA). Subsequent grafting with azido-terminated poly(ethylene glycol) (PEG) produces bottlebrush copolymers. Analysis of bottlebrush copolymer samples using atomic force microscopy (AFM) revealed a surface morphology of toroid-shaped nanostructures, consistent with the polypeptoid backbone having cyclic architecture. Small-angle neutron scattering (SANS) characterization of the bottlebrush polymer ensemble in solution also confirms the cyclic architecture of the polypeptoid backbones

Numerical Study of the Movement of Fine Particle in Sound Wave Field

AbstractInhalable particulate matter, especially PM2.5 is one of the main pollutants in China and it's harmful to both human health and atmosphere. Since the removal efficiency of traditional dust removal devices such as ESP for PM2.5 is very low, pretreatment becomes necessary before the dust gets into the dust remover. Acoustic agglomeration is one of the pretreatment technologies which uses sound wave with high intensity to make fine particles get agglomerate and grow up, and improves the efficiency of traditional dust removal devices for PM2.5. In sound wave field, fine particles are carried by the medium which in this paper is air, and vibrate with different amplitude because of different particle sizes, thus relative movement appears and then particles have more chances to collide and get agglomerate. In this paper, the movement of particles with different sizes in travelling wave sound field and standing wave sound field were calculated, including the velocity, displacement, amplitude and so on. The situation that Re<1 was considered and Viscous force in Stokes region was chose as the main forces here. Studying the movement of fine particle in sound field with different conditions has great meaning in learning the mechanisms of acoustic agglomeration