The trade-off between taxi time and fuel consumption in airport ground movement

Environmental impact is a very important agenda item in many sectors nowadays, which the air transportation sector is also trying to reduce as much as possible. One area which has remained relatively unexplored in this context is the ground movement problem for aircraft on the airport’s surface. Aircraft have to be routed from a gate to a runway and vice versa and it is still unknown whether fuel burn and environmental impact reductions will best result from purely minimising the taxi times or whether it is also important to avoid multiple acceleration phases. This paper presents a newly developed multi-objective approach for analysing the trade-off between taxi time and fuel consumption during taxiing. The approach consists of a combination of a graph-based routing algorithm and a population adaptive immune algorithm to discover different speed profiles of aircraft. Analysis with data from a European hub airport has highlighted the impressive performance of the new approach. Furthermore, it is shown that the trade-off between taxi time and fuel consumption is very sensitive to the fuel-related objective function which is used

A real-time active routing approach via a database for airport surface movement

Airports face challenges due to the increasing volume of air traffic and tighter environmental restrictions which result in a need to actively integrate speed profiles into conventional routing and scheduling procedure. However, only until very recently, the research on airport ground movement has started to take into account such a speed profile optimisation problem actively so that not only time efficiency but also fuel saving and decrease in airport emissions can be achieved at the same time. It is envisioned that the realism of planning could also be improved through speed profiles. However, due to the multi-objective nature of the problem and complexity of the investigated models (objective functions), the existing speed profile optimisation approach features high computational demand and is not suitable for an on-line application. In order to make this approach more competitive for real-world application and to meet limits imposed by International Civil Aviation Organization for on-line decision time, this paper introduces a pre-computed database acting as a middleware to effectively separate the planning (routing and scheduling) module and the speed profile generation module. Employing a database not only circumvents duplicative optimisation for the same taxiway segments, but also completely avoids the computation of speed profiles during the on-line decision support owing a great deal to newly proposed database initialization procedures. Moreover, the added layer of database facilitates, in the future, more complex and realistic models to be considered in the speed profile generation module, without sacrificing on-line decision time. The experimental results carried out using data from a major European hub show that the proposed approach is promising in speeding up the search process

The electric double layer has a life of its own

Using molecular dynamics simulations with recently developed importance sampling methods, we show that the differential capacitance of a model ionic liquid based double-layer capacitor exhibits an anomalous dependence on the applied electrical potential. Such behavior is qualitatively incompatible with standard mean-field theories of the electrical double layer, but is consistent with observations made in experiment. The anomalous response results from structural changes induced in the interfacial region of the ionic liquid as it develops a charge density to screen the charge induced on the electrode surface. These structural changes are strongly influenced by the out-of-plane layering of the electrolyte and are multifaceted, including an abrupt local ordering of the ions adsorbed in the plane of the electrode surface, reorientation of molecular ions, and the spontaneous exchange of ions between different layers of the electrolyte close to the electrode surface. The local ordering exhibits signatures of a first-order phase transition, which would indicate a singular charge-density transition in a macroscopic limit

Preference-based evolutionary algorithm for airport surface operations

In addition to time efficiency, minimisation of fuel consumption and related emissions has started to be considered by research on optimisation of airport surface operations as more airports face severe congestion and tightening environmental regulations. Objectives are related to economic cost which can be used as preferences to search for a region of cost efficient and Pareto optimal solutions. A multi-objective evolutionary optimisation framework with preferences is proposed in this paper to solve a complex optimisation problem integrating runway scheduling and airport ground movement problem. The evolutionary search algorithm uses modified crowding distance in the replacement procedure to take into account cost of delay and fuel price. Furthermore, uncertainty inherent in prices is reflected by expressing preferences as an interval. Preference information is used to control the extent of region of interest, which has a beneficial effect on algorithm performance. As a result, the search algorithm can achieve faster convergence and potentially better solutions. A filtering procedure is further proposed to select an evenly distributed subset of Pareto optimal solutions in order to reduce its size and help the decision maker. The computational results with data from major international hub airports show the efficiency of the proposed approach.This work is supported in part by the Engineering and Physical Sciences Research Council (EPSRC) under Grant EP/H004424/1, EP/N029496/1 and EP/N029496/2

FORMATION OF OLIGOMERIC FERROCENES

Abstract not availabl

Design of a zero emission aircraft towing system

Even though aircraft have become less pollutant over the years, the increase in air traffic results in a growing production of emissions in the aviation industry. In other words, the annual decrease in pollution due to more fuel efficient aircraft, cannot compete with the increase of pollution caused by air traffic growth. Unlike the aviation sector, most sectors can replace fossil fuels with alternate energy sources, but the airline industry is currently confined to kerosene for flight operations. On the ground, electric taxiing is an alternative to conventional taxiing, which would have less impact on the environment and could solve aircraft congestion problems at airports. This research focuses on the feasibility of an airport based electric towing system, which eliminates the need for using fossil fuels while on the ground as much as possible

Analysis of current situation and expected future bottlenecks and challenges in air cargo - First results of CargoMap project

The paper focuses on the first results of the EU Air Cargo Technology Roadmap project (CargoMap). The project investigates if novel aircraft is needed to satisfy the demand for air cargo and develops an air cargo technology roadmap. The goal of this study is to identify and examine the factors influencing medium to long-term air freight development in order to gain a better understanding of the air freight transport system and its interdependencies. The outcome of this analysis is intended to provide a basis for the development of a technology roadmap for future concepts (e.g. vehicles, operations, etc.) in air freight transport

CargoMap: An Air Cargo Technology Road Map

This paper focuses on the first results of the Air Cargo Technology Roadmap project (CargoMap) that is supported by the European Commission. The project investigates if novel aircraft are needed to satisfy the demand for air cargo in the long term future and develops an air cargo technology roadmap. The outcome of the market analysis is intended to provide a basis for the development of technology for future concepts (e.g. vehicles, operations, etc.) in air freight transport. The study is supporting the content of the Horizon 2020 technology program