• Aircraft taxi time prediction: Comparisons and insights

      Ravizza, Stefan; Chen, Jun; Atkin, Jason A. D.; Stewart, Paul; Burke, Edmund K.; University of Lincoln (Elsevier, 2014-01)
      The predicted growth in air transportation and the ambitious goal of the European Commission to have on-time performance of flights within 1 min makes efficient and predictable ground operations at airports indispensable. Accurately predicting taxi times of arrivals and departures serves as an important key task for runway sequencing, gate assignment and ground movement itself. This research tests different statistical regression approaches and also various regression methods which fall into the realm of soft computing to more accurately predict taxi times. Historic data from two major European airports is utilised for cross-validation. Detailed comparisons show that a TSK fuzzy rule-based system outperformed the other approaches in terms of prediction accuracy. Insights from this approach are then presented, focusing on the analysis of taxi-in times, which is rarely discussed in literature. The aim of this research is to unleash the power of soft computing methods, in particular fuzzy rule-based systems, for taxi time prediction problems. Moreover, we aim to show that, although these methods have only been recently applied to airport problems, they present promising and potential features for such problems.
    • Energy harvesting and power network architectures for the multibody advanced airship for transport high altitude cruiser-feeder airship concept

      Smith, Tim; Bingham, Chris; Stewart, Paul; Allarton, R.; Stewart, Jill; University of Lincoln (Institution of Mechanical Engineers, 2013-01-09)
      This article presents results of preliminary investigations in the development of a new class of airship. Specific focus is given to photo-electric harvesting as a primary energy source, power architectures and energy audits for life support, propulsion and ancillary loads to support the continuous daily operation of the primary airship (cruiser) at stratospheric altitudes (similar to 15 km). The results are being used to drive the requirements of the FP7 multibody advanced airship for transport programme, which is to globally transport both passengers and freight using a 'feeder-cruiser' concept. It is shown that there is a potential trade off to traditional cost and size limits and, although potentially very complex, a first-order approximation is used to demonstrate sensitivities to the economics of the lifting gas. This presented concept is substantially different to those of conventional aircraft due to the airship size and the inherent requirement to harvest and store sufficient energy during 'daylight' operation to guarantee safe operation during 'dark hours'. This is particularly apparent when the sizing of the proposed electrolyser is considered, as its size and mass increases nonlinearly with decreasing daylight duty. The study also considers the integration of photovoltaics with various electrical architectures, in safety critical environments. A mass audit is also included that shows that if the electrolyser was omitted in such systems, the overall impact will be small compared to structural and propulsion masses. It should be noted that although the technology bias is application specific, the underlying principles are much widely applicable to other energy harvesting and power management sectors.
    • Increasing aeronautic electric propulsion performances by cogeneration and heat recovery

      Trancossi, Michele; Dumas, Antonio; Stewart, Paul; Vucinic, Dean; University of Lincoln; University of Hull (Society of Automotive Engineers, 2014)
      Emissions from aviation have become a focus of increasing interest in recent years. The growth of civil aviation is faster than nearly all other economic sectors. Increased demand has led to a higher growth rate in fossil fuels consumption by the aviation sector. Despite more fuel-effcient and less polluting turbofan and turboprop engines, the growth of air travel contributes to increase pollution attributable to aviation. Aircraft are currently the only human-made in situ generators of emissions in the upper troposphere and in the stratosphere. The depletion of the stratosphere's ozone layer by CFCs and related chemicals has underscored the importance of anticipating other potential insults to the ozone layer. Different possible solutions have been advanced to reduce the environmental impact of aviation, such as electrication of ground operations, optimization of airline timetables and airspace usage, limitation of cruise altitude and increased use of turboprop aircrafts. Those improvements seem very limited answers, which allow only marginal reduction of the environmental footprint of air transport. Breakthrough concepts such as the all-electric aircrafts must be considered. Today state of electric-propulsion is demonstrating a lack of performance and operative range if compared to traditional propulsion concepts. This paper presents a novel concept which has been only envisaged before based on the increase of the performance and range of electric airplanes by an effective cogeneration on board. This concept aims to allow effective and more efcient electric aeronautic propulsion through next generation of green all electric propulsion
    • Integrated flight/thrust vectoring control for jet-powered unmanned aerial vehicles with ACHEON propulsion

      Cen, Zhaohui; Smith, Tim; Stewart, Paul; Stewart, Jill; University of Lincoln (2014-07-29)
      As a new alternative to tilting rotors or turbojet vector mechanical oriented nozzles, ACHEON (Aerial Coanda High Efficiency Orienting-jet Nozzle) has enormous advantages because it is free of moving elements and highly effective for Vertical/Short-Take-Off and Landing (V/STOL) aircraft. In this paper, an integrated flight/ thrust vectoring control scheme for a jet powered Unmanned Aerial Vehicle (UAV) with an ACHEON nozzle is proposed to assess its suitability in jet aircraft flight applications. Firstly, a simplified Thrust-Vectoring (TV) population model is built based on CFD simulation data and parameter identification. Secondly, this TV propulsion model is embedded as a jet actuator for a benchmark fixed-wing ‘Aerosonde’ UAV, and then a four “cascaded-loop” controller, based on nonlinear dynamic inversion (NDI), is designed to individually control the angular rates (in the body frame), attitude angles (in the wind frame), track angles (in the navigation frame), and position (in the earth-centered frame) . Unlike previous research on fixed-wing UAV flight controls or TV controls, our proposed four-cascaded NDI control law can not only coordinate surface control and TV control as well as an optimization controller, but can also implement an absolute self-position control for the autopilot flight control. Finally, flight simulations in a high-fidelity aerodynamic environment are performed to demonstrate the effectiveness and superiority of our proposed control scheme.
    • A novel genetic programming approach to the design of engine control systems for the voltage stabilization of hybrid electric vehicle generator outputs

      Gladwin, Daniel; Stewart, Paul; Stewart, Jill; University of Sheffield; University of Lincoln (Institution of Mechanical Engineers, 2011-07-13)
      This paper describes a Genetic Programming based automatic design methodology applied to the maintenance of a stable generated electrical output from a series-hybrid vehicle generator set. The generator set comprises a three-phase AC generator whose output is subsequently rectified to DC. The engine/generator combination receives its control input via an electronically actuated throttle, whose control integration is made more complex due to the significant system time delay. This time delay problem is usually addressed by model predictive design methods, which add computational complexity and rely as a necessity on accurate system and delay models. In order to eliminate this reliance, and achieve stable operation with disturbance rejection, a controller is designed via a Genetic Programming framework implemented directly in Matlab and, particularly, Simulink. The principal objective is to obtain a relatively simple controller for the time-delay system which does not rely on computationally expensive structures, yet retains inherent disturbance rejection properties. A methodology is presented to automatically design control systems directly upon the block libraries available in Simulink to automatically evolve robust control structures.
    • Primary and albedo solar energy sources for high altitude persistent air vehicle operation

      Smith, Tim; Trancossi, Michele; Vucinic, Dean; Bingham, Chris; Stewart, Paul; University of Lincoln; Sheffield Hallam University; Vrije Universiteit Brussel; University of Derby (Multidisciplinary Digital Publishing Institute (MDPI), 2017-04-22)
      A new class of the all electric airship to globally transport both passengers and freight using a ‘feeder‐cruiser’ concept, and powered by renewable electric energy, is considered. Specific focus is given to photo‐electric harvesting as the primary energy source and the associated hydrogen‐based energy storage systems. Furthermore, it is shown that the total PV output may be significantly increased by utilising cloud albedo effects. Appropriate power architectures and energy audits required for life support, and the propulsion and ancillary loads to support the continuous daily operation of the primary airship (cruiser) at stratospheric altitudes (circa 18 km), are also considered. The presented solution is substantially different from those of conventional aircraft due to the airship size and the inherent requirement to harvest and store sufficient energy during “daylight” operation, when subject to varying seasonal conditions and latitudes, to ensure its safe and continued operation during the corresponding varying “dark hours”. This is particularly apparent when the sizing of the proposed electrolyser is considered, as its size and mass increase nonlinearly with decreasing day‐night duty. As such, a Unitized Regenerative Fuel Cell is proposed. For the first time the study also discusses the potential benefits of integrating the photo‐voltaic cells into airship canopy structures utilising TENSAIRITY®‐based elements in order to eliminate the requirements for separate inter‐PV array wiring and the transport of low pressure hydrogen between fuel cells.
    • Real-time thermal management of permanent magnet synchronous motors by resistance estimation

      Wilson, S. D.; Stewart, Paul; Stewart, Jill; University of Lincoln (IET, 2012)
      Real-time thermal management of electrical machines relies on sufficiently accurate indicators of internal temperature.One indicator of temperature in a permanent-magnet synchronous motor is the stator winding resistance. This study applies twocurrent injection techniques to a commercially produced permanent-magnet servomotor, which are applicable under load andcause minimal disturbance to the shaft torque. The current injection techniques applied here enable the temporary boosting ofresistive voltage and consequent application to low-resistance, high-voltage machines. The effectiveness of the approach isdemonstrated by tracking the change in winding temperature during a 2 h load cycle.
    • A review of thrust-vectoring in support of a V/STOL non-moving mechanical propulsion system

      Páscoa, José; Dumas, Antonio; Trancossi, Michele; Stewart, Paul; Vucinic, Dean; University of Lincoln (2013-01-01)
      Abstract The advantages associated to Vertical Short-Take-Off and Landing (V/STOL) have been demonstrated since the early days of aviation, with the initial technolology being based on airships and later on helicopters and planes. Its operational advantages are enormous, being it in the field of military, humanitarian and rescue operations, or even in general aviation. Helicopters have limits in their maximum horizontal speed and classic V/STOL airplanes have problems associated with their large weight, due to the implementation of moving elements, when based on tilting rotors or turbojet vector mechanical oriented nozzles. A new alternative is proposed within the European Union Project ACHEON (Aerial Coanda High Efficiency Orienting-jet Nozzle). The project introduces a novel scheme to orient the jet that is free of moving elements. This is based on a Coanda effect nozzle supported in two fluid streams, also incorporating boundary layer plasma actuators to achieve larger deflection angles. Herein we introduce a state-of-the-art review of the concepts that have been proposed in the framework of jet orienting propulsion systems. This review allows to demonstrate the advantages of the new concept in comparison to competing technologies in use at present day, or of competing technologies under development worldwide.
    • The trade-off between taxi time and fuel consumption in airport ground movement

      Ravizza, Stefan; Chen, Jun; Atkin, Jason A. D.; Burke, Edmund K.; Stewart, Paul; University of Lincoln (2013-02-13)
      Environmental issues play an important role across many sectors. This is particularly the case in the air transportation industry. 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 a key area of study is whether fuel burn and environmental impact improvements 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.