To improve the compactness, broadband, high gain and wide coverage performance of the shortwave antenna (array), this paper introduces the array technology from the LPDA unit antenna, establishes the compact optimization model of the 2×3 elements LPDA fan-shaped array, and proposes an optimization method applied to the broadband decoupling and grating lobe suppression for LPDA fan-shaped phased array, taking the broadband low coupling and non-grating lobe as constraints; By using phased array technology, the wide scanning characteristics of LPDA fan-shaped array are analysed, and the influence of antenna parameters on the mutual coupling is studied when LPDA phased array widely scan. Finally, the feasibility of the truss based 2×3 elements LPDA fan-shaped phased array with a scale of 1:60 is verified through tests. The fan-shaped phased array has a frequency coverage of 13~28 MHz, an average gain of 17.5 dBi in the band, an average beam width of ≥ 30 °, and a scanning range of ≥ 90 °. The proposed array has the characteristics of broadband, low coupling, high gain, wide scanning and compactness. The proposed joint optimization method provides a very promising technical means for the optimization design of complex multi-dimensional phased arrays.

An original analysis of Fabry–Perot cavity antennas based on thick partially reflecting sheet (PRS) is presented in this work. The bandwidth enhancement of such radiating devices with respect to Fabry–Perot cavity antennas based on thin PRS has been investigated through a leaky-wave, transverse-equivalent-network approach, and a field matching technique. This analysis led to an optimal condition for considerably improving the gain-bandwidth figure of merit for this class of radiating devices on a sound physical basis. A Fabry–Perot cavity antenna based on a thick PRS working at 60 GHz is discussed as a case study. An excellent impedance matching is finally achieved by means of an efficient feeding network designed through a fast ad hoc, hybrid, analytical-numerical method. Theoretical results are in an excellent agreement with full-wave simulations corroborating the proposed methods.

Flow separation in highly loaded axial compressors remains a major barrier to performance, motivating the search for active flow control strategies. This study investigates air injection to energise low-momentum endwall flow in a tandem stator configuration, representing the first investigation of its kind for tandem vanes. A numerical investigation was conducted, starting with a smooth-casing reference case and progressing to parametric studies of slot geometry (inclination $\alpha $, jet angle $\beta $, radius of curvature ${R_c}$, circumferential width ${w_c}$), relative injection mass flow rate ${\dot m_{inj}}/{\dot m_{stall}}$ and axial location $\zeta $. The results show how each parameter influences efficiency and pressure ratio, yielding design guidelines: shallow $\alpha $, moderate $\beta $ towards the separation zone, relatively large ${R_c}$ and a balanced ${w_c}$–${\dot m_{inj}}/{\dot m_{stall}}$ combination, best captured through the momentum coefficient ${C_u}$ and velocity ratio ${u_{inj}}/{u_\infty }$. Injection near $\zeta \approx 1.2$ (just upstream of separation) proved most effective, and off-design simulations showed larger efficiency gains towards de-throttled conditions, although stall margin was unaffected. Robustness was confirmed through turbulence-model comparisons and injector turbulence variations, which consistently reproduced suppression of suction-side separation. An integrated analysis of aerodynamic losses further showed that injection strategies remain beneficial when loss penalties are considered. The study thus establishes transferable guidelines for injector design in tandem stators, providing a foundation for future optimisation and experimental validation.

Unstable approaches contribute significantly to accidents during the critical approach and landing phases of flight, many of which could have been prevented by executing a go-around. This review investigates cognitive lockup, a tendency to adhere to task completion despite shifting priorities, and its role in aviation incidents. Specifically, we explore the psychological underpinnings of cognitive lockup, the influence on pilot decision-making and potential mitigation strategies. We examine factors such as task completion bias, framing effects and the perceived cost of task switching, and provide recommendations for training and policy modifications to reduce cognitive lockup. Aviation safety in critical flight phases can be improved through enhanced pilot training, mindfulness techniques, positive policy framing and AI-based alert systems.

The increase in activities related to unmanned aircraft systems and the implementation of this new ecosystem have introduced new hazards, impacting the operational safety of air traffic, particularly near airports, creating risks and disruptions in the flow of aircraft. The establishment of airspace for unmanned traffic management has required the integration of this new airspace with the existing one, bringing the potential for issues from this integration. A method was identified as needed to guide the detection of hazards posed to air traffic control activities and the consequent implementation of required mitigation measures. The aim of this work is to propose a framework for identifying hazards introduced to air traffic control, with a view to ensure the safe transition of this process. The method involved consulting air traffic operational safety specialists via a questionnaire, presenting the hazards highlighted in the literature concerning the integration of new airspace concepts within air traffic control activities. The results, obtained through a Delphi consultation, were analysed based on the most frequently assigned scores (mode) to reflect expert consensus. The results were organised into the proposed framework, establishing a guide to risk management activities aimed at implementing the change. The resulting structure was re-submitted to specialists and validated based on the Delphi method. Contributions to society include a guide for this process and potential future implementations, while the literature gap was addressed by adding knowledge to the scientific process.

This study presents the design and evaluation of an autonomous landing system for rotary-wing unmanned aerial vehicles (UAVs) targeting moving platforms. The proposed system leverages the UAV’s onboard positional data and the moving platform’s position, velocity and orientation information to execute high-precision landings. By incorporating the GPS coordinates provided by the mobile platform, the operational envelope of the landing procedure is significantly extended. A Kalman filter is employed to fuse the platform’s GPS data with the UAV’s inertial orientation measurements, enabling accurate estimation of a dynamic rendezvous point along the platform’s trajectory. This facilitates the generation of an optimised landing trajectory that minimises path length and enhances energy efficiency.

A YOLOv8-based object detection model is integrated into the system to detect the landing pad in real time. The effectiveness of the proposed method is validated through scenario-based simulations designed to evaluate landing performance under variable altitudes, crosswind disturbances and limited visibility due to fog.

Across 30 independent runs, the proposed method reduced total autonomous landing time by 12% (191 ± 2.0 s → 168 ± 1.6 s, p < 0.001), halved the landing phase (22.9 ± 0.7 s → 11.1 ± 0.7 s), shortened the path by ≍152 m (2035 ± 6.8 m → 1883 ± 3.1 m), and lowered battery consumption from 5.0 ± 0.1% to 4.0 ± 0.1%. The system maintained successful landings under variable wind (up to 6 m/s) and fog with a 7 m detection range, achieving sub-meter touchdown accuracy (RMSE ≍ 0.15 m); at a 5 m detection limit, landings failed, indicating a robustness boundary.

Compared to existing literature, the developed system introduces a novel 3D trajectory planning approach involving altitude variations and dynamic target prediction. The framework is modular and compatible with various UAV and ground vehicle platforms, making it suitable for diverse mission profiles in both civilian and defense applications.

This paper presents the design and analysis of the Triple band Circular Quarter Mode Substrate Integrated Waveguide (QMSIW) 1 × 2 MIMO antenna for sub-6 GHz 5 G wireless applications. The antenna operates at three distinct frequencies those are 3.57GHz, 4.41GHz and 5.43 GHz respectively. The 3.57 GHz used to operate for WiMAX, 5 G, and Fixed Wireless Access, the 4.41 GHz, is often used for specific satellite uplink/downlink operations, Radar Systems and the third one 5.43 GHz is used for Wi-Fi, DSRC, and WLAN systems. The proposed architectural design underwent simulation utilizing electromagnetic (EM) tools to the extract results, followed by antenna fabrication and measured results, it was observed that there is a close match between the simulation, measured results and validated results. The measured, simulation gain values are 5.092dBi,4.98dBi at 3.57 GHz, 4.51dBi,4.6dBi at 4.41 GHz and 3.075dBi,3.06dBi at 5.43 GHz frequency, while also demonstrating satisfactory isolation between the ports, quantified as being less than −15 dB. The characteristic parameters of the MIMO antenna, including a diversity-gain (DG) surpassing 9.95 dB (>9.95 dB), alongside an envelope-correlation-coefficient (ECC) of less than 0.0001, Mean effective gain (MEG) lies between − 3 dB to − 4 dB, among any two radiating elements at every operational frequency, indicate that the antenna has been meticulously designed.