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The maximum allowable turning speed of an aircraft is a critical factor affecting the safety of civil aviation. Evaluating the maximum permissible taxiing turn speed for civil aircraft is an essential aspect of aircraft design. To ensure that the aircraft does not experience unbalanced forces leading to a lateral rollover due to excessive taxiing speed, an engineering estimation method is employed to study the maximum permissible taxiing turn speed for civil aircraft. This method begins with certain assumptions and calculation scenarios, followed by the derivation of a calculation model based on the analysis of aircraft forces. Lastly, a case study of a specific aircraft’s maximum taxiing turn speed is conducted in conjunction with practical engineering considerations. The study reveals that as crosswind forces on civil aircraft increase, the maximum turning speed decreases. Moreover, for lighter aircraft with a forward center of gravity, the risk of lateral rollovers is higher. These findings underscore the engineering applicability of the estimation method.

In this paper, the stochastic propagation of the aircraft taxiing under the excitation of uneven runway is investigated based on physics-informed neural networks (PINNs). In particular, we successfully applied the PINNs with layer-wise locally adaptive activation functions (L-LAAF) and the learning rate decay strategy to address the challenging task of parameter identification for some aircraft systems. Specifically, the accuracy and effectiveness of the proposed method in solving the time-dependent Fokker–Planck equation for systems were first demonstrated. Subsequently, the proposed method is effectively utilized to identify the damping coefficient of landing gear and the aircraft body weight. Through numerical experiments and comparisons, we have demonstrated that incorporating L-LAAF and learning rate decay strategies can further enhance the performance of the network. The numerical simulation based on Monte Carlo fully validates the method. The development of physics-based deep learning techniques for aircraft system parameter identification research can help researchers better understand and control the behavior of systems, providing effective solutions for optimizing system design.

There is limited evidence of work-related transmission in the emerging coronaviral pandemic. We aimed to identify high-risk occupations for early coronavirus disease 2019 (COVID-19) local transmission. In this observational study, we extracted confirmed COVID-19 cases from governmental investigation reports in Hong Kong, Japan, Singapore, Taiwan, Thailand, and Vietnam. We followed each country/area for 40 days after its first locally transmitted case, and excluded all imported cases. We defined a possible work-related case as a worker with evidence of close contact with another confirmed case due to work, or an unknown contact history but likely to be infected in the working environment (e.g. an airport taxi driver). We calculated the case number for each occupation, and illustrated the temporal distribution of all possible work-related cases and healthcare worker (HCW) cases. The temporal distribution was further defined as early outbreak (the earliest 10 days of the following period) and late outbreak (11th to 40th days of the following period). We identified 103 possible work-related cases (14.9%) among a total of 690 local transmissions. The five occupation groups with the most cases were healthcare workers (HCWs) (22%), drivers and transport workers (18%), services and sales workers (18%), cleaning and domestic workers (9%) and public safety workers (7%). Possible work-related transmission played a substantial role in early outbreak (47.7% of early cases). Occupations at risk varied from early outbreak (predominantly services and sales workers, drivers, construction laborers, and religious professionals) to late outbreak (predominantly HCWs, drivers, cleaning and domestic workers, police officers, and religious professionals). Work-related transmission is considerable in early COVID-19 outbreaks, and the elevated risk of infection was not limited to HCW. Implementing preventive/surveillance strategies for high-risk working populations is warranted.

The increasing attention of opinion towards climate change has prompted public authorities to provide plans for the containment of emissions to reduce the environmental impact of human activities. The transport sector is one of the main ones responsible for greenhouse emissions and is under investigation to counter its burdens. Therefore, it is essential to identify a strategy that allows for reducing the environmental impact produced by aircraft on the landing and take-off cycle and its operating costs. In this study, four different taxiing strategies are implemented in an existing Italian airport. The results show advantageous scenarios through single-engine taxiing, reduced taxi time through improved surface traffic management, and onboard systems. On the other hand, operating towing solutions with internal combustion cause excessive production of pollutants, especially HC, CO, NOX, and particulate matter. Finally, towing with an electrically powered external vehicle provides good results for pollutants and the maximum reduction in fuel consumption, but it implies externalities on taxiing time. Compared to the current conditions, the best solutions ensure significant reductions in pollutants throughout the landing and take-off cycle (−3.2% for NOx and −44.2% for HC) and economic savings (−13.4% of fuel consumption).

To enhance the autonomy and safety of civil aircraft during takeoff, deviation-correction, pitch tracking, and airspeed tracking control laws are designed based on the civil aircraft ground taxiing model, enabling automatic takeoff from ground taxiing to liftoff. Firstly, a combined correction control law using nose wheel steering and rudder deflection is designed based on this basis, and a power function-shaped influence factor is introduced for control allocation between the two. Secondly, a pitch angle tracking control law is designed for the transition phase from three-wheel to two-wheel ground taxiing. For the liftoff phase, an airspeed tracking control law is designed, with pitch angle as the inner loop and speed as the outer loop. A fade-out device is introduced to enable smooth transitions from the pitch tracking control command to the speed tracking control command. Finally, the effectiveness of the proposed combined correction, pitch tracking, and speed tracking control laws are verified through numerical simulations.

In response to the requirement for traction sliding mode in a follow-up steering function, a follow-up steering system with static pressure support is built, using the traction conditions of the B737-800 as a case study. To achieve optimal working conditions in the new traction taxiing mode, simulations of the fluid domain and analyses of bearing characteristics are conducted, revealing the impact of system parameters on the distribution of the pressure and velocity fields of the turntable under standard operating conditions. The precise impacts of parameters like oil supply pressure and orifice diameter on the oil film-bearing performance of vertical and radial turntables are investigated in greater detail. By analyzing the distribution of oil film pressure and velocity under varying conditions, the influence of these parameters on total bearing capacity is ascertained. The performance offers a theoretical foundation and direction for the design and optimization of hydrostatic turntables, presenting significant practical value.

Over the past few years, the rapid growth of air traffic and the associated increase in emissions have created a need for sustainable aviation. Motivated by these challenges, this paper explores how a 50-passenger regional aircraft can be hybridized to fly with the lowest possible emissions in 2040. In particular, the use of liquid hydrogen in this aircraft is an innovative power source that promises to reduce CO2 and NOx emissions to zero. Combined with a fuel-cell system, the energy obtained from the liquid hydrogen can be used efficiently. To realize a feasible concept in the near future considering the aspects of performance and security, the system must be hybridized. In terms of maximized aircraft sustainability, this paper analyses the flight phases and ground phases, resulting in an aircraft design with a significant reduction in operating costs. Promising technologies, such as a wingtip propeller and electric green taxiing, are discussed in this paper, and their potential impacts on the future of aviation are highlighted. In essence, the hybridization of regional aircraft is promising and feasible by 2040; however, more research is needed in the areas of fuel-cell technology, thermal management and hydrogen production and storage.

Accurate yaw angle information is essential for reliable aircraft ground maneuver, but inertial measurements obtained during taxiing are often corrupted by high-frequency noise. To improve signal quality, a double-integrator observer is designed to reconstruct the yaw rate dynamics and attenuate measurement noise. Building on the refined state estimates, a fast sliding-mode controller is developed to achieve rapid and robust tracking of the reference yaw angle in the presence of model uncertainties. The proposed approach is validated through a six-degree-of-freedom aircraft simulation model.

This paper compares onboard Energy Storage Solutions (ESSs) for a Kinetic Energy Recovery System (KERS) from a landing aircraft. Energy is stored temporarily and reused so that it enables engine-less taxiing. This paper evaluates the choice of onboard Energy Storage Solutions (ESSs) (flywheels, batteries and supercapacitors) for recovering energy during the landing roll and storing it in the device. A design of an ESS with each of the three technologies was made, using commercially available products. The resulting devices are compared on the basis of weight, charging time, discharging time and complexity in retrofitting to existing systems. Results shows that while batteries have the highest energy density and will have the lowest weight, they are unable to charge/discharge quickly enough to satisfy this application. Conversely, supercapacitors have this ability but their low energy density make them heavy which in turn would offer penalty to the aircraft in flight. Flywheels emerge as the most interesting proposition due to their high energy density and fast charging ability, which satisfy the requirements for application.