Fuel hedging is a common risk management tool used in the airline industry. But past studies have not addressed the question of whether fuel hedging creates any benefit to airline operations. This study is the first work that empirically examines the role of fuel hedging in reducing airlines’ operating costs. Using US airlines data from 2000 through 2012, we find that, after accounting for the ...

Proton exchange membrane fuel cells are promising energy sources that produce electrical currents with almost null pollutant emissions, and they have been received growing attention in recent years. Maintaining a fuel cell system in correct operating conditions requires good system control. Based on the mathematical model of proton exchange membrane fuel cells, model linearization is carried ou...

Keywords: Jet aircraft Fuel price Operating cost Leontief technology Translog a b s t r a c t Investigation of the airline response to a fuel price increase is in effect an investigation of the role of variable interactions in aircraft cost models. We examine the impact of fuel price on aircraft costs and airline operational strategies by developing two classes of operating cost models for jet ...

The connection between PEM fuel cells and common DC-DC converters is examined. The analysis is model-based and done for boost, buck and buck-boost converters. In a first step, the effect of the converter ripples upon the PEM fuel cell is shown. They introduce oscillations in the fuel cell. Their appearance is explained, discussed and possibilities for their suppression are given. After that, th...

Maintaining a fuel cell system in correct operating conditions when subjected to fast load changes requires good system control. In order to design such a controller, a simple PEFC system model describing all the important system dynamics and cross couplings is required. The simple model shown here describes the fuel cell auxiliary systems in a state space approach, linking user input to fuel c...

output characteristics of fuel cells are affected by a large number of parameters such as geometry, dimensions, construction materials and conditions of supplying fluids. in this paper a mathematical model followed by a two-dimensional numerical approach has been presented to study the fuel cell parametrically. effect of oxygen concentration at gas diffusion layer entrance, temperature and pres...

Air pollution is one of the major issues about the diesel engines in todays' world. It is a special concern in those areas that have difficulty meeting health-based outdoor air quality standards. Natural gas has low emission and resource abundance and also conventional compression ignition engine can be easily converted to a dual fuel mode to use natural gas as main fuel and diesel as pilot ...

The aim of this work is to investigate the influence of NO/SO2 on the emissions of N2O from diesel engine. A direct-injection diesel engine (model NF-19SK YANMAR) one cylinder was employed to test the emission. This engine works on fourstroke cycle and was operated at 2200 rpm by 25, 50, and 75% engine load. The experiment by three level sulfur content of fuel by adding DBDS into MDO and experi...

The only significant development of the AUS system has been an extension.of the available cross-sections. That portion of the ENDF/B V data files which is unrestricted has been acquired from the IAEA Nuclear Data Section and the data processed for the AUS.ENDF2006 group library as required. In particular, a large set of fission product data has been processtid, sufficient for calculations of bo...