Aircraft Towing Research Articles

An adaptive large neighborhood search heuristic for solving a robust gate assignment problem

Robust gate assignment problem with transfer passengers and tows is considered.A large neighborhood search heuristic is proposed to solve the integrated problem.Extensive experiments are conducted to justify the performance of our approach. With the rapid growth of air traffic demand, airport capacity becomes a major bottleneck within the air traffic control systems. Minor disturbances may have a large impact on the airport surface operations due to the overly tight schedules, which results in frequent gate conflict occurrences during airports daily operations. A robust gate schedule that is resilient to disturbances is essential for an airport to maintain a good performance. Unfortunately, there is no efficient expert system available for the airport managers to simultaneously consider the traditional cost (the aircraft tow cost, transfer passenger cost) and the robustness. To fill this gap, in this paper, we extend the traditional gate assignment problem and consider a wider scope, in which the traditional costs and the robustness are simultaneously considered. A mathematical model is first built, which leads to a complex non-linear model. To efficiently solve this model, an adaptive large neighborhood search (ALNS) algorithm is then designed. We novelly propose multiple local search operators by exploring the characteristics of the gate assignment problem. The comparison with the benchmark algorithm shows the competitiveness of proposed algorithm in solving the considered problem. Moreover, the proposed methodology also has great potential from the practical perspective since it can be easily integrated into current expert systems to help airport managers make satisfactory decisions.

Alternative fuel technologies

This article looks at the use of alternative fuel technologies at airport ground handling operations. It discusses how electric vehicles are being successfully used as ground service vehicles, especially as aircraft towing tractors. These vehicles use their battery weight to counterbalance the aircraft weight, thus allowing the vehicle to lift the nose wheel and tow the aircraft. The lead-acid batteries used by these electric vehicles typically require only one charge a day and can have life endurance of up to fifteen years.

Complete hydraulic drive system for aircraft tow truck

Complete hydraulic drive system for aircraft tow truck

Acoustic optic hybrid (AOH) sensor

The ability of laser vibrometers to receive and process acoustic echoes from the water surface above a submerged target is established and evaluated. Sonar echoes from a submerged target are collected from the water surface by a laser vibrometer. Feasibility of this approach to sensing underwater sound is demonstrated. If the acoustic excitation at an otherwise undisturbed water surface is 195 to 168 dB re: 1 microPa, signal-to-noise ratio (SNR), at the vibrometer output, is shown to range from about 46 to 6 dB. Capillary waves and gravity waves at the water surface are expected and shown to have some destructive effect on the process of echo retrieval. A series of experiments to quantify the surface wave effects is described. The wave experiment results are reported. A successful attempt to acquire echoes from a submerged target over a grid of points for further processing into a three-dimensional image is made and described. The data acquisition and beamforming techniques constitute a three-dimensional, acoustic optic, synthetic aperture sonar (SAS). Beamformed images are included. For an aircraft towing acoustic sensors through the water with a mechanical link, this technique holds the promise of increased safety and improved fuel efficiency.

Numerical Computation of Differential-Algebraic Equations for Non-Linear Dynamics of Multibody Systems Involving Contact Forces

The well known Euler-Lagrange equations of motion for constrained variational problems are derived using the principle of virtual work. These equations are used in the modelling of multibody systems and result in differential-algebraic equations of high index. Here they concern an N-link pendulum, a heavy aircraft towing truck and a heavy off-highway track vehicle. The differential-algebraic equation is cast as an ordinary differential equation through differentiation of the constraint equations. The resulting system is computed using the integration routine LSODAR, the Euler and fourth order Runge-Kutta methods. The difficulty to integrate this system is revealed to be the result of many highly oscillatory forces of large magnitude acting on many bodies simultaneously. Constraint compliance is analyzed for the three different integration methods and the drift of the constraint equations for the three different systems is shown to be influenced by nonlinear contact forces.

First Order for an Aircraft Tow Tractor of the Future

Goldhofer Fahrzeugwerk GmbH & Co. just received its first order for a towbarless aircraft towing tractor, type AST 1. The order has been placed by SWISSAIR, which intends to operate the tow tractor at the Zürich airport after its delivery in July 1991. The delivery scope amounts to approx. DM 2M. It is expected that SWISSAIR will meet its further demand for aircraft tow tractors in the coming years by the latest Goldhofer technology. Two vehicle sizes (AST 1: 100 t — 450 t take‐off weight and AST 2:40t — 180t take‐off weight) cover most internationally used aircraft models.

Performance of an Omnidirectional Wheel on Snow and Ice

ABSTRACTA brief study was performed to investigate the suitability of service vehicles equipped with a unique omnidirectional wheel operating aboard aircraft carriers in northern latitudes, where ice and snow on flight decks is not uncommon. This study addressed the comparative performance of the omnidirectional wheel, a bias‐ply highway tire as used on current Navy MD‐3 aircraft tow vehicles, a typical nonpneumatic forklift truck tire, and an automotive radial‐ply all‐season tire. The tires were tested for driving traction levels on prepared ice, hard‐packed snow, and fresh shallow snow. In general, the omnidirectional wheel showed performance superior to the forklift truck tire and the bias‐ply highway tire. The radial all‐season tire, however, outperformed the omnidirectional wheel in traction on slippery surfaces. The omnidirectional wheel was found to be well‐behaved during traction testing and shows promise for operation on winter surfaces. Recommendations are provided that might further improve omnidirectional wheel performance on snow and ice.

Reducing Air Pollutant Emissions at Airports by Controlling Aircraft Ground Operations

Potential reductions in air pollutant emissions were determined for four strategies to control aircraft ground operations at two case study airports, Los Angeles and San Francisco International Airports. Safety, cost, and fuel savings associated with strategy implementation were examined. Two strategies, aircraft towing and shutdown of one engine during taxi operations, provided significant emission reductions. However, there are a number of safety problems associated with aircraft towing. The shutdown of one engine while taxiing was found to be the most viable strategy because of substantial emission reductions, cost benefits resulting from fuel savings, and no apparent safety problems.

Airports international

In connection with their programme of expansion and their purchase of Boeing aircraft IRAQI AIRWAYS are equipping the airport of Baghdad with modern aircraft towing tractors.

Aerial Dispersal in a Known Spider Population

Although it has been known since the time of Aristotle that spiders can make airborne excursions, the first accurate observations were published by the pioneer British arachnologist, John Blackwall (1827). It was not until some years later that McCook (1877, 1878, 1889-93) made the suggestion that such behaviour might be a means of dispersal for the species concerned and during the last fifty years a number of arachnologists have published observations on this subject (Nielsen 1932, Braendegaard 1937, 1938, 1946, Bristowe 1929, 1939, Berland 1932, Smith 1904, Emerton 1908, 1919, McKeown 1952). In addition to the work of these observers, the contribution made by spiders to aerial plankton has been demonstrated by collections from aircraft towing nets (Collins & Baker 1934, Crosby & Bishop 1936, Glick 1939) and from nets on wireless masts (Freeman 1946) and the masts of ships (Hardy & Milne 1937). Generally speaking only small numbers were taken, though Glick was able to collect about 1500 specimens, including 4 at 5000 ft. Freeman used three nets 1 yd in diameter, and during 1934 and from March to April 1935 he took 134 specimens, representing twenty species. On the other hand, Owen & Le Gros (1954) found that seventy meals taken by swifts in July and August 1952, July 1953 and July 1944 contained 1425 spiders, representing about twenty-two species. Bristowe (1939) gives an excellent account of dispersal behaviour and summarizes much of the published work. The following general points emerge: