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Airport capacity management
Published in Gert Meijer, Fundamentals of Aviation Operations, 2020
A special type of weather-dependent operation is in de-icing aircraft prior to take-off. This is necessary for aircraft operations in freezing conditions, whereby snow, water or moist quickly become ice on the aircraft’s wing surface, if not at the airport than at low altitudes shortly after take-off. Departing with ice on the wing’s surface is dangerous and often results in a fatal incident; de-icing therefore is directly related to flight safety.
Warning and protection systems
Published in David Wyatt, Mike Tooley, Aircraft Electrical and Electronic Systems, 2018
The fluid can also be applied on the ground by specially equipped vehicles with booms to allow easy access to the entire aircraft. De-icing fluids are typically composed of ethylene glycol or propylene glycol, together with thickening agents, corrosion inhibitors, and coloured dye. The aircraft is sprayed with a fluid that melts any existing ice on the aircraft and also prevents ice formation prior to takeoff. The timing of when the aircraft is sprayed has to take into account the weather conditions (in particular ambient temperature, wind speed, precipitation, humidity) aircraft skin temperature, and the scheduled departure time.
Operational disruption management
Published in Peter J. Bruce, Yi Gao, John M. C. King, Airline Operations, 2018
Winter is unique not only due to the possibility of heavy snow or freezing precipitation, but because of potentially extensive de-icing delays. Meteorologists have become very accurate in their ability to predict with a high level of confidence not only when snow will begin, but what type of accumulations can be expected, as well as whether the snow is likely to be wet or dry. Airlines can use that information to reduce or suspend operations, depending on the severity of a storm. Safety is always an airline’s highest priority, but ensuring an acceptable level of passenger experience is also important. There are many reasons for which an airline would reduce its schedule at one of its larger airports, but here is one example. An airline has four de-icing pads. With two crews working on each pad in moderate snow, de-icing might average fifteen minutes per aircraft, one aircraft per pad. That means the best throughput they can expect is four aircraft per pad per hour, or sixteen departures per hour, as a best case. Even if the rate were reduced to sixteen per hour, it is important those sixteen are staggered as much as possible to minimize delays. If all sixteen arrive in a bank and then push back at roughly the same time, the delays will be much longer than desired. If they are scheduled at a rate of twenty arrivals per hour, it will not take long for the delays to become unacceptable not only to the airline, but to its passengers.
Experimental investigation surface abrasion resistance and surface frost resistance of concrete pavement incorporating fly ash and slag
Published in International Journal of Pavement Engineering, 2021
Ouming Xu, Sen Han, Yamin Liu, Chao Li
The objective of this study was to investigate the effects of the type and amount of fly ash and slag on the mechanical properties and surface durability of PCC pavement. Conventional testing procedures, such as cubic compressive strength test, and flexural test, were employed to evaluate the concrete with or without supplementary cementitious materials. And, the surface durability was characterised though surface abrasion test and surface frost resistance test, respectively. The surface abrasion test was selected to simulate the road surface abrasion suffered from vehicle tires action. The surface frost resistance test with water or saturated sodium chloride solution was utilised to simulate the freeze–thaw effect on road surface of by water or deicing agent in cold weather. Additionally, microstructure analysis of surface PCC pavement was carried out by means of scanning electron microscopy (SEM) to explain the effect of the supplementary cementitious materials on the concrete structures.
Recent research and development programs for infrastructures maintenance, renovation and management in Japan
Published in Structure and Infrastructure Engineering, 2020
Yozo Fujino, Dionysius M. Siringoringo
In many cases, deteriorations of concrete structure are caused by the corrosion of reinforcing steels. Corrosion of the steels in concrete is accelerated by airborne salt from the sea or road salt used for deicing. To prevent this, stainless steel has been applied to reinforcing rebar in some cases. However, it is not widely used because of its prohibitive expensive cost. Chromium (Cr) bearing steel is seen as an attractive alternative of the high corrosion resistant steel. The corrosion resistance of Cr bearing steel in concrete depends on the rust (corrosion product) on the surface under actual environment. In the case of the low alloy weathering steel, there have been many reports analysing the rust formation and the effect of alloying element. However, the structure of the rust on Cr bearing steel is still not fully understood.
Analysis of metal corrosion methods and identification of cost-efficient and low corrosion deicing agents
Published in Corrosion Engineering, Science and Technology, 2023
Michael R. Gruber, Bernhard Hofko, Markus Hoffmann, David Stinglmayr, Hinrich Grothe
The primary purpose of deicing in winter maintenance is to provide a sufficient level of skid resistance by avoiding freezing due to preventive spreading or to remove residual snow and ice by applying deicing agents. The necessary amount for the latter is determined by the deicing performance, which states the amount of ice or snow that can be deiced (in grams ice per gram deicing agent, g/g) at a given temperature. Given that deicing performance is largely based on the freezing curve, it decreases for all deicers at low temperatures.