In the field of civil aviation, the nose landing gear is a critical component that is prone to damage during taxiing. With the advent of new technologies such as towing taxi-out and hub motors, the nose landing gear faces increasingly complex operational environments, thereby imposing higher performance demands. Ensuring the structural safety of the nose landing gear is fundamental for the successful application of these technologies. However, current research on aircraft nose landing gear under these new conditions is somewhat lacking, particularly in terms of reliable analysis models for real-world scenarios. This study focuses on a typical Class C aircraft, specifically the B-727 model, for which a finite element model of the nose landing gear is developed. Modal testing of the aircraft’s nose landing gear is conducted using the impact hammer method, and the results are compared with those from the simulations. The experimental data indicate that the error range for the first seven natural frequencies is between 0.23% and 9.27%, confirming the high accuracy of the developed landing gear model. Furthermore, with towing taxi-out as the primary scenario, a dynamic model of the aircraft towing system is established, and an analysis on the structural strength and topological optimization of the nose landing gear under various conditions, including high speeds and heavy loads, is performed. The results show that the developed model can effectively support the analysis and prediction of the mechanical behavior of the nose landing gear. Under high-speed, heavy-load conditions, the nose landing gear experiences significantly increased loads, with the maximum deformation primarily occurring at the lower section of the shock strut’s outer cylinder. However, no damage occurred. Additionally, under these conditions, an optimized structural design for the landing gear was identified, which, while ensuring structural strength, achieves a 22.32% reduction in the mass of the outer cylinder, also ensuring safety in towing taxi-out conditions.

The traditional method of taxiing for civil aircraft, which relies on their engines, may be surpassed by the new method of towing taxi-out due to its superior advantages such as reduced energy consumption, lower emissions, and higher efficiency. However, the towing taxi-out system poses a challenge to lateral stability due to the concentration of mass at the rear, leading to severe instability when turning at high speeds. To address this issue, a nonlinear civil aircraft towing and taxiing system model and a linear four-degree-of-freedom civil aircraft towing and taxiing system reference model were established using TruckSim and Matlab/Simulink software. The fuzzy proportional–integral–derivative controller was utilized, with the braking torque of each wheel serving as the control variable and the real-time yaw rate difference and its rate of change as the fuzzy control input. The controller was compared and validated with a traditional PID controller. The results of the simulation showed that the fuzzy PID control has better nonlinear characteristics and stronger adaptability to operating conditions compared to traditional PID control, providing timely, effective, adaptive, and robust control effects for the vehicle dynamics model. Under the fuzzy PID control, the peak yaw speed of the civil aircraft decreased to 10 degrees per second under double-shift conditions, representing an increase of 23.1%. Furthermore, the lateral stability and safety of the towing taxi-out system were improved, as evidenced by the reduction in the yaw rate of the tractor and civil aircraft under the hook condition. The use of this controller provides valuable technical guidance and support for the practical development and safe application of the towed glide mode.

A new towing taxi-out departure mode has become the preferred choice to replace the traditional departure mode of civil aircraft due to its obvious advantages of low energy consumption, low emissions, and high efficiency. However, the inertia may lead to potential lateral instability and even “Jack-knifing”, as the mass of the system is concentrated in the rear. In this paper, the lateral instability mechanism and influencing factors of the civil aircraft towing taxi-out system were studied using computer virtual simulation technology and taking Boeing 737–400 and AM210 tractors as research objects. The results show that the “Jack-knifing” phenomenon was caused by the lateral instability of the system when the sliding speed of the system was more than 15 km/h, and the system was accompanied by the lateral slip condition. Furthermore, the safety zone, side-show zone and jack-knifing zone of the system were defined in terms of towing speed and steering angle. Additionally, a towing safety zone was created under different airport track conditions by analyzing the lateral stability of the system. The conclusion of this study may provide a theoretical basis and reference for the safe application of the new taxi-out departure mode.

The permeation and absorption of solutes into human hair are highly relevant to various applications, including the formulation of hair-care products, the development of water pollution control and remediation, and the risk assessment of environmental exposure. Based on a detailed introduction of the structure and composition of hair, the effects of the properties of hair (structure, composition, and charge properties), the physicochemical properties of solutes (molecular size, shape, and hydrophobicity), and the conditions of the surrounding medium (solvent composition, temperature, and pH) on the permeation and absorption were comprehensively analyzed. Several theoretical models were reviewed, including two-part/two-state, porous media diffusion, homogeneous medium diffusion, heterogeneous medium partition, and diffusion models. Finally, future research directions for the permeation and absorption of solutes in hair were proposed to provide a foundation for the further optimization and application of permeation models.

With the advantages of low fuel consumption, high departure efficiency, and green environmental protection, the new civil aircraft departure mode of towing taxi-out has become the preferred mode of civil aircraft departure for future smart airports. The process of civil aircraft towing departure requires close collaboration and effective communication among multiple staff members, and accidents are mostly caused by human errors. Therefore, it is crucial to perform human reliability analysis. However, there are few reports or human reliability studies on civil aircraft towing departure accidents. Although the Success Likelihood Index Method (SLIM) based on expert ex-perience may be an effective tool for assessing human reliability, SLIM relies heavily on expert judgment to determine model parameters, which makes the method subjective and uncertain to varying degrees. To overcome this, the present study uses the Demp-ster–Shafer evidence theory to extend SLIM by fusing the judgments given by different experts, providing more accurate and reliable results. Herein, the proposed model is used to study human reliability in the process of civil aircraft towing departure. The results are conducive to reducing the human error probability of the staff involved in the civil aircraft towing departure process and improving the overall safety level of departure operations.

Green towing departure represents a significant approach towards achieving green civil aviation, offering greater efficiency and environmental benefits compared to traditional departure methods. To accurately predict pilots’ visual attention allocation during towing departure and ensure safe operations, this paper proposes a predictive model based on information expectancy and an enhanced information value function. To validate the model, an instrument monitoring experiment was conducted with 14 participants under varying task weights and information presentation formats in a towing-departure context. Gaze-point distribution was recorded as an indicator of attention allocation. Participants monitor target information displayed on a simulated Head-Up Display (HUD) interface and respond to anomalies by pressing designated keys. The experimental results indicate that there is a significant correlation and good agreement between the theoretical values of attention allocation calculated using the proposed model and the actual gaze point distributions observed in the experiment. These findings provide a basis for the design of aircraft cockpit display interfaces.