高性能混凝土经飞机除冰液长期作用的化学腐蚀

飞机除冰液对机场高性能混凝土(HPC)长期作用的腐蚀性未知,采用浸泡腐蚀法经过4 a测定了普通水泥混凝土(OPC)和HPC分别在水、25%乙二醇(飞机除冰液)和25%商用飞机除冰液(LBR-A除冰液)中的抗腐蚀性。结果表明,除冰液与OPC表层的CH发生化学腐蚀反应,产生结晶腐蚀产物,使得混凝土试件质量不减反增,LBR-A除冰液对混凝土表层的腐蚀性比乙二醇更强一些。但除冰液的长期作用并不能对水泥混凝土的内部结构造成实质性影响,仅限于表层的逐层剥蚀。因此,在商用飞机除冰液的长期腐蚀作用下,用硅酸盐水泥掺加40%粉煤灰(FA)配制的HPC抗腐蚀性最好,用抗硫酸盐硅酸盐水泥掺加40%FA配制的HPC抗腐蚀性次之,OPC抗腐蚀性较差。     

融雪、排水、降噪沥青路面路用性能研究

采用自制的环保型融雪剂及橡胶高粘高弹改性沥青制备出新型的融雪、排水、降噪沥青路面,相比普通融雪剂制备的除冰路面具有水稳定性能好、抗滑性能好等优点。融雪、排水、抗滑沥青混合料融雪除冰效果显著,各项路用性能优异,动稳定度达到8 000次/mm以上,3次冻融循环劈裂强度比超过80%。     

Modelling the fate of organic micropollutants in stormwater ponds

Urban water managers need to estimate the potential removal of organic micropollutants (MP) in stormwater treatment systems to support MP pollution control strategies. This study documents how the potential removal of organic MP in stormwater treatment systems can be quantified by using multimedia models. The fate of four different MP in a stormwater retention pond was simulated by applying two steady-state multimedia fate models (EPI Suite and SimpleBox) commonly applied in chemical risk assessment and a dynamic multimedia fate model (Stormwater Treatment Unit Model for Micro Pollutants — STUMP). The four simulated organic stormwater MP (iodopropynyl butylcarbamate — IPBC, benzene, glyphosate and pyrene) were selected according to their different urban sources and environmental fate. This ensures that the results can be extended to other relevant stormwater pollutants. All three models use substance inherent properties to calculate MP fate but differ in their ability to represent the small physical scale and high temporal variability of stormwater treatment systems. Therefore the three models generate different results. A Global Sensitivity Analysis (GSA) highlighted that settling/resuspension of particulate matter was the most sensitive process for the dynamic model. The uncertainty of the estimated MP fluxes can be reduced by calibrating the dynamic model against total suspended solids data. This reduction in uncertainty was more significant for the substances with strong tendency to sorb, i.e. glyphosate and pyrene and less significant for substances with a smaller tendency to sorb, i.e. IPBC and benzene. The results provide support to the elaboration of MP pollution control strategies by limiting the need for extensive and complex monitoring campaigns targeting the wide range of specific organic MP found in stormwater runoff.     

提高水泥混凝土路面盐冻破坏的主要措施

从物理作用和化学作用两方面分析了混凝土受除冰盐侵蚀破环的机理,提出了提高混凝土抗盐冻破环的主要措施,指出只要把混凝土内的饱水度控制在很低的水平上,混凝土的盐冻剥蚀破坏就可以大为降低,从而为以后水泥混凝土路面的施工及其养护提供经验。     

The impact of tourism on airport efficiency: The Spanish case

This paper considers the impact of tourism on airports efficiency. Using stochastic frontier analysis (SFA) methods, an input-oriented distance function was estimated for a sample of 35 Spanish airports over the 2009 to 2016 period. Air transport and tourism are highly connected. Results suggest that tourist-oriented airports may achieve higher efficiency levels than non-touristic ones. We also demonstrate a relationship between airline business models for tourist arrivals and airport efficiency. Airports with higher shares of "low-cost carrier" passenger traffic appear to perform more efficiently. By comparison, airports with higher shares of “charter passenger” traffic appear to perform less efficiently.     

Structural and operational management of Turkish airports: a bootstrap data envelopment analysis of efficiency

This paper explores the structural and operational dimensions of the efficiencies of airports. The two-stage procedure is suggested to assess the efficiencies of airports in this study. In the first-stage, Classification and Regression Tree, which is one of the machine-learning approaches used to divide the airports into homogeneous and thus comparable sub-groups. In the second stage, the bootstrap data envelopment analysis approach obtains more precise structural and operational efficiency scores. To illustrate the proposed framework use, we applied it to a real case associated with Turkish airports. The results demonstrate that this framework presents a more comprehensive assessment of airport performance rather than conventional data envelopment analysis models. Moreover, it provides to show the deficiencies of the structural and operational management of airports. The findings can help anywhere airport authorities as well as Turkish airport authorities.     

Briefly Noted

Planning for future airport access should reflect the rise and prospective dominance of low-cost airlines. Air transport now serves a mass market, focused on costs. Increasingly, metropolitan airport passengers use multiple airports. Many airport employees ride public transportation to work. Together, these facts undermine the case for special-purpose, high-speed modes of airport access and argue for more cost-effective modes of public transport that distribute both passengers and employees effectively over metropolitan regions. While some extensions of municipal rail transit systems may be appropriate, planners should pay close attention to a range of rubber-tired, high-occupancy vehicles which can respond to the evolving needs of travelers and employees such as bus rapid transit.     

Incentivize It and They Will Come? How Some of the Busiest U.S. Airports Are Building Air Service With Incentive Programs

Problem, research strategy, and findings: In the 1990s, the Federal Aviation Administration (FAA) prohibited airport sponsors (local authorities managing airports) from diverting airport revenue to general municipal budgets and allowed the busiest airports to create air service incentive programs (ASIPs) to induce airlines to launch new air service. These incentive programs have not been evaluated, although planners need information on their long-term effectiveness. Few data, however, are available on ASIP programs; I created a database to identify which airports have ASIPs, which new airline services received incentives, and the services that continued after incentives ended. I find that 26 of 44 airports with ASIPs that recruited new routes spent $171.5 million combined between 2012 and the first quarter of 2015, 40% on routes that were not retained when the incentive ended. The busiest airports in the largest cities with growing populations, relatively independent of local economic status, were most able to recruit and retain new airline services. Small and medium airports, particularly in stagnant areas, were not able to recruit and retain new air services.

Takeaway for practice: The FAA should require airport sponsors to submit comprehensive information on their ASIP programs—the routes recruited and retained, as well as detailed estimates of the costs and benefits of each route—to provide planners with needed information. The FAA also should loosen the constraints on the use of non-aeronautical airport revenues so that communities can choose between spending on incentives to increase air service and other programs to increase local economic development.     

机场工程建设安全管控模式研究——以浦东国际机场三期扩建工程为例

随着信息化、全球经济化的发展,人们出行面临越来越多的选择,特别是航空出行越来越成为更多人的选择,因此 对于民用机场的新建、改扩建等越来越迫在眉睫。民用机场工程建设扩张也带来危机,安全方面的困境层出不穷,安全管理 理念越来深入人心,机场的建设给管理和运行带来更高的要求。大型枢纽机场不能再停留在传统的工程项目管理水平上,而 是要建立科学有效的体系、采取有效的措施,在施工安全管控上加强与完善。以浦东国际机场三期扩建工程为例,以施工阶 段业主方的角度阐述机场工程建设安全管控模式。以期为类似工程建设安全管控提供借鉴和指导。     

Effect of deicing solutions on the tensile strength of micro- or nano-modified asphalt mixture

This paper reports on the potential benefits of micro- or nano-sized materials for asphalt mixtures used on pavements, specifically when they are exposed to water or deicing solutions. Asphalt mixtures were prepared with various amount of nanoclay and/or carbon microfiber, and compacted using the Superpave? gyratory compactor. Moisture susceptibility and deicer impacts were assessed by exposing the samples to water or deicing chemicals (NaCl, MgCl₂ and CaCl₂), and seven freeze–thaw cycles, in a modified AASHTO T283 test. Comparisons of micro- or nano-modified asphalt mixtures exposed to deicers are made based on results of indirect tensile strength tests, which preliminarily demonstrate the great potential of using microfibers and nanoclays in asphalt mixture for improved performance. Based on the results, it was found that the addition of nanoclay and carbon microfiber would improve a mixture’s moisture susceptibility performance or decrease the moisture damage potential in most cases. The detailed effects of deicing solutions on the tensile strength of micro- or nano- modified asphalt mixture are discussed in this paper.     

A total environmental risk assessment model for international hub airports

This paper presents a multi-criteria decision analysis for environmental risk assessment (ERA) with regard to avoiding and eliminating damages and loss under natural disasters in international airport projects. It starts from an assumption that the strategy of eliminating damages and losses under natural disasters is related to the location selection problem, and it is necessary to use the multi-criteria decision analysis for calculated decision-making support. The paper uses the analytic network process (ANP) to demonstrate one of its utility modes in decision-making support to location selection problems, which aims at an evaluation of different projects from different locations. A set of generic criteria for risk assessment at international projects was put forward to support ANP modelling, and it was due to the consideration of social, technical, economic, environmental and political (STEEP) criteria related to the built, social and natural (BSN) trinity environment of international airport projects. At the end, an experimental case study on three international hub airports in China is given to test the ANP model called ERA.Airport, and it is concluded that ANP can be effectively used for risk assessment in the specific utility mode. The ERA.Airport is a generic multi-criteria decision-making model and can be used across the world for accurate environmental risk assessment for international airports.     

机场一种文化景观?

在20世纪,机场已被理解和设计为一种文化景观和独特环境。尽管机场在其演化过程中被各种批评家、建筑师和哲学家描述为是一种反景观,过时的"非场所"和反乌托邦,但总体上对机场和航空的理解已经与景观、环境、生态的概念紧密地交织在一起。机场被认为是一种文化景观和一种脆弱的容易被破坏的环境,这种观点引发且起因于对机场特定地点的景观设计,对野生动物的管理实践,在机场设计中纳入历史遗迹、以及以废旧机场的适应性再利用为目的的飞机跑道和其他特征的保护。尽管很多设计师把机场构想为新的标志性的高科技文化景观,其他设计师则认为机场破坏了现有的文化景观。机场作为文化景观的理念也因此总是与其周围的社会、经济和政治密切相关。这篇文章把机场作为景观的思想,融入到文化景观自身概念的变化解释中,这种理念在动力飞行诞生的那几年中,第一次在英美世界得到更广泛和准确的运用。     

The Dark Side of Aeromobilities: Unplanned Airport Planning in Mexico City

Land-use conflicts, noise and health problems, local air pollution, decreased urban quality and affected liveability are considered amongst the core impacts and consequences associated with global airports, all of which have largely been individually documented. Through a case study of Mexico City International Airport (MCIA), this article argues that a more integrated focus that brings such various issues and perspectives together is needed in order to widen the understanding of the existing relationship between socio-spatial and environmental effects, increased aeromobility, airport siting conflicts, airport urban surroundings and globalization. The present study of MCIA suggests that local players and airports are not just passively influenced by processes of globalization and aeromobilities, but also that such processes disentangle a wide array of socio-spatial and environmental consequences that depend on ad hoc local contexts. Hence, the article follows the argument that a much stronger focus on the planning process of airports is needed at local and regional scales, while a larger debate regarding the regulation of increased global aviation ought to be raised in national and international contexts.     

机场旧道面板再生粗集料在场道工程中的研究与应用

简要介绍了机场旧道面板的破碎与加工技术,分析并比较了再生粗集料(Recycled Coarse Aggregate,文中简称RCA)与天然粗集料(Natural Coarse Aggregate,文中简称NCA)的各项性能指标,重点研究了再生集料在基层中的应用,尝试性的研究了再生粗集料在混凝土中的应用。研究认为,旧道面板再生粗集料的技术性能指标可以满足机场场道工程垫层、基层及普通混凝土所用集料规范要求。通过华北两个机场(文中简称G工程、Y工程)的应用情况来看,旧道面板再生粗集料在机场场道工程中的利用是可行的,同时在节能环保和经济效益方面实现了双重突破。     

Size fractionation of metals in runoff from residential and highway storm sewers

Stormwater sampling for particulate, colloidal, and dissolved metals was conducted for several storms at six outfalls in Monmouth County, NJ. Samples were initially sequentially filtered through 5 microm, 0.45 microm, and 10 kDa filters. Of the heavy metals, Cu and Zn were mostly either dissolved (<10 kDa) (20-100%) or in the particulate size fractions >5 microm (0->70%). Pb and Cr were associated exclusively with particles >5 microm in size. Fe, Al, and Si were found mostly in larger size fractions (>70%), with smaller amounts 0.45-5 microm in size. Preliminary data from a small set of samples passed through coarser filters suggested that metals may actually be largely associated with particles larger than 20 microm. Variable and sometimes large dissolved fractions of Cu and Zn can contribute to erratic metals removal by structural best management practices (e.g., wet ponds, detention basins). The size fractionation of stormwater constituents has implications for the design and performance of stormwater control structures and the aquatic toxicity risks posed by the metals. The results demonstrate the importance of obtaining particle size data when planning stormwater treatment.     

Quantification of uncertainty in modelled partitioning and removal of heavy metals (Cu,Zn) in a stormwater retention pond and a biofilter

Strategies for reduction of micropollutant (MP) discharges from stormwater drainage systems require accurate estimation of the potential MP removal in stormwater treatment systems. However, the high uncertainty commonly affecting stormwater runoff quality modelling also influences stormwater treatment models. This study identified the major sources of uncertainty when estimating the removal of copper and zinc in a retention pond and a biofilter by using a conceptual dynamic model which estimates MP partitioning between the dissolved and particulate phases as well as environmental fate based on substance-inherent properties. The two systems differ in their main removal processes (settling and filtration/sorption, respectively) and in the time resolution of the available measurements (composite samples and pollutographs). The most sensitive model factors, identified by using Global Sensitivity Analysis (GSA), were related to the physical characteristics of the simulated systems (flow and water losses) and to the fate processes related to Total Suspended Solids (TSS). The model prediction bounds were estimated by using the Generalized Likelihood Uncertainty Estimation (GLUE) technique. Composite samples and pollutographs produced similar prediction bounds for the pond and the biofilter, suggesting a limited influence of the temporal resolution of samples on the model prediction bounds. GLUE highlighted model structural uncertainty when modelling the biofilter, due to disregard of plant-driven evapotranspiration, underestimation of sorption and neglect of oversaturation with respect to minerals/salts. The results of this study however illustrate the potential for the application of conceptual dynamic fate models base on substance-inherent properties, in combination with available datasets and statistical methods, to estimate the MP removal in different stormwater treatment systems and compare with environmental quality standards targeting the dissolved MP fraction.     

City planning and municipal airports, 1927–40

The period between 1927 and 1940 represented an important formative period in the history of the relationship between city planners and airports. During two periods of intense interest (1927–30 and 1937–40), planners expressed some of their earliest, most basic ideas concerning the relationship between airports, cities and city planning. Planners essentially viewed airports as parts of the local transportation infrastructure and envisaged the airplane as contributing to urban decentralization. Central to their thoughts during the first period of airport enthusiasm was the notion that cities would have to build elaborate systems of airports. The systems were metropolitan in nature and focused on moving planes and people within the metropolitan area. Planners did not seem to strongly view airports as part of a national system of transportation. By the latter period, planners had a greater sense of airports as parts of a national system of transportation, but still viewed them as part of the local transportation infrastructure. Throughout this formative period, planners and their ideas were rather peripheral to local airport construction and development. However, planners did introduce the concept of airport zoning, a tool cities used after World War II to shape land-use at and around their airports.     

Intra-event variability of Escherichia coli and total suspended solids in urban stormwater runoff

Sediment levels are important for environmental health risk assessments of surface water bodies, while faecal pollution can introduce significant public health risks for users of these systems. Urban stormwater is one of the largest sources of contaminants to surface waters, yet the fate and transport of these contaminants (especially those microbiological) have received little attention in the literature. Stormwater runoff from five urbanized catchments were monitored for pathogen indicator bacteria and total suspended solids in two developed countries. Multiple discrete samples were collected during each storm event, allowing an analysis of intra-event characteristics such as initial concentration, peak concentration, maximum rate of change, and relative confidence interval. The data suggest that a catchment’s area influences pollutant characteristics, as larger catchments have more complex stormwater infrastructure and more variable pollutant sources. The variability of total suspended solids for many characteristics was similar to Escherichia coli, indicating that the variability of E. coli may not be substantially higher than that of other pollutants as initially speculated. Further, variations in E. coli appeared to be more commonly correlated to antecedent climate, while total suspended solids were more highly correlated to rainfall/runoff characteristics. This emphasizes the importance of climate on microbial persistence and die off in urban systems. Discrete intra-event concentrations of total suspended solids and, to a lesser extent E. coli, were correlated to flow, velocity, and rainfall intensity (adjusted by time of concentrations). Concentration changes were found to be best described by adjusted rainfall intensity, as shown by other researchers. This study has resulted in an increased understanding of the magnitude of intra-event variations of total suspended solids and E. coli and what physical and climatic parameters influence these variations.     

Internalizing airport congestion

The problem of airport congestion is treated in the literature analogously to road congestion. However, the phenomenon is different, because entry at airports is not random. Flight delays are a consequence of system overload, even though airport systems operate on carefully planned schedules. Besides uncontrolled for events (e.g. bad weather), airport congestion is a result of decisions of airports’ managers and airlines. These agents are interested in using airport infrastructure too close to its maximum capacity, ignoring the negative impacts caused on passengers. Another characteristic of airport congestion is that it exhibits a cascade-type of effect not present in road congestion: one single delay may generate an impact which accumulates over the next hours. Therefore, congestion pricing should not be identified with peak-pricing as a solution for the problem experienced at airports. In this paper, a theoretical model shows that airport congestion pricing should pursue the internalization of externalities generated by agents’ decisions. Congestion fees charged on airports and airlines should reflect the external costs imposed on each other and on passengers, when they respectively decide the number of slots offered and the tightness of flight schedules.     

Structural efficiency assessment of regional airports: Lessons from India

This study focuses on the structural efficiency of 42 Indian regional airports over five years from 2014 to 2019. A two-stage data envelopment analysis (DEA) was applied to assess the structural efficiencies of airports. We find that distance to the closest airport, distance from the city centre, per capita income, accessibility and profitability of the airport significantly impact the structural efficiency scores. We also calculate the productivity growth of the sample airports over five years using the Malmquist Productivity Index. Airport productivity rankings and sources of inefficiency provide airport authorities and policymakers with valuable insights into the potential for improvement.