Search Results (331)

This study presents a photonic integrated optical sensor based on a dual-polarization microring resonator with angular gratings on a silicon-on-insulator (SOI) waveguide, enabling simultaneous and precise refractive index (RI) and temperature measurements. Due to the distinct energy distributions for transverse electric ($\mathit{TE}$) and transverse magnetic ($\mathit{TM}$) modes in SOI waveguides, these modes show distinct sensitivity responses to the variation in ambient RI and temperature. Simultaneous measurements of both temperature and RI are enabled by exciting both these transverse modes in the microring resonator structure. Furthermore, incorporating angular gratings into the microring resonator’s inner sidewall extends the temperature measurement range by mitigating free spectral range limitations. This work presents a novel approach to dual-polarization microring resonators with angular gratings, offering an enhanced temperature measurement range and detection limit in optical sensing applications requiring an extended temperature range. The proposed structure is able to yield a simulated temperature measurement range of approximately 35 nm with a detection limit as low as $2.99\times {10}^{-5}$. The achieved temperature sensitivity is 334 pm/°C and RI sensitivity is 13.33 nm/RIU for the ${\mathit{TE}}_0$ mode, while the ${\mathit{TM}}_0$ mode exhibits a temperature sensitivity of 260 pm/°C and an RI sensitivity of 76.66 nm/RIU. Full article

This study systematically compares the metrological characteristics of single- exposure, double-exposure, and continuous-exposure holographic interferometry for micro-deformation detection. Results demonstrate that the double-exposure method achieves optimal balance across critical performance metrics through its ideal cosine fringe field modulation. This approach (1) eliminates object wave amplitude interference via dual-exposure superposition, establishing submicron linear mapping between fringe displacement and deformation amplitude; (2) introduces a fringe gradient-based direction detection algorithm resolving deformation vector ambiguity; and (3) implements an error-compensated fusion framework integrating theoretical modeling, MATLAB 2015b simulations, and experimental validation. Experiments on drilled glass samples confirm their superior performance in terms of near-ideal fringe contrast (1.0) and noise suppression (0.06). The technique significantly improves real-time capability and anti-interference robustness in micro-deformation monitoring, providing a validated solution for MEMS and material mechanics characterization. Full article

This study introduces enhanced artificial intelligence (AI)-assisted terrain-aided navigation (TAN) for a sophisticated jet trainer, building upon our prior researchby incorporating real-flight test validation. The proposed TAN integrates a high-performance terrain server, a digital elevation model, and an efficient line-of-sight algorithm to facilitate terrain-aided navigation. The system utilizes an advanced search algorithm in conjunction with two filter designs, including adaptive filters that dynamically optimize navigation precision and operational efficiency. A significant development is the AI model’s capacity to independently alternate between the resource-intensive search algorithm and a set of filters, thereby maintaining navigational accuracy while facilitating in-flight execution without supplementary hardware requirements. Comprehensive Monte Carlo calculations, validated by flight test instrumentation (FTI) data, indicate that the proposed TAN consistently facilitates low-altitude navigation across diverse operational settings. The incorporation of actual flight data not only substantiates the system’s efficacy but also offers novel perspectives on practical implementation obstacles and improvements. These findings signify an advancement in autonomous terrain-aided navigation, connecting simulation with actual flight performance. Full article

This study investigates the noise impact on reconstructed images in computer-generated holography (CGH) through theoretical analysis and Matlab 2015b simulations. By quantitatively injecting noise to mimic practical interference environments, we systematically analyze the degradation mechanisms of four CGH types: detour-phase, modified off-axis beam reference, kinoform, and interference type. A dual-metric evaluation framework combining peak signal-to-noise ratio (PSNR) and the Structural Similarity Index Measure (SSIM) is proposed. Results demonstrate that increasing noise intensity induces progressive declines in reconstruction quality, manifested as PSNR reduction and SSIM-based structural fidelity loss. The findings provide theoretical guidance for noise suppression, parameter optimization, and algorithm selection in CGH systems, advancing its applications in optical encryption and high-precision imaging. Full article

The importance of gust detection and its impact on flight is a broad and critical subject, particularly in the context of flight safety. When a gust is detected early through appropriate methods, the pilot can adjust the aircraft’s flight state accordingly, thereby reducing the risk associated with adverse atmospheric conditions. Without timely intervention, such conditions may compromise safety margins. If early detection is not achieved, the time available for an effective response is significantly reduced. This study investigates state-of-the-art gust detection methods, with a particular focus on their relevance during the final approach phase of flight. A theoretical framework is developed, leading to the formulation of a novel gust detection method. The proposed approach was tested under simulated conditions using an experimental setup comprising both software and hardware components. The simulation environment modelled rapid changes in wind conditions affecting an aircraft, enabling the validation of the method’s capability to estimate gust characteristics. The final analysis evaluates the method’s accuracy using simulation-derived data and discusses its performance, including identified limitations. The findings contribute to the development of more robust gust detection systems and support ongoing efforts to enhance flight safety, particularly during critical flight phases. Full article

This article presents the development and implementation of an automated digital test bench for fault diagnosis in the caution and warning panels of the UH-60 helicopter, using practices based on NASA’s systems engineering process. The research addresses the critical need to improve efficiency and accuracy in aeronautical maintenance by automating processes traditionally relying on manual techniques. Throughout the study, advanced software engineering methodologies were implemented to develop a system that significantly reduces diagnostic times and enhances the accuracy and reliability of results by integrating digital signal processing. The article highlights the economic benefits, demonstrating a substantial reduction in repair costs, and emphasizes the system’s flexibility to adapt to other aeronautical components, establishing a solid foundation for future technological innovations in aircraft maintenance. The novelty of this paper lies in integrating real-time simulation with a closed-loop diagnostic system designed primarily for the UH-60 avionics panels. This approach has not previously been applied to this series of aircraft or aeronautical components, allowing for adaptive and automated fault detection and significant improvement in diagnostic accuracy and speed in unscheduled aeronautical maintenance environments. Full article

Following the promising performance of the seamless morphing trailing edge (SMTE) flap and its internal actuation system, the elephant trunk mechanism (ETM), investigated through aerodynamic and structural analyses, this study presents an experimental analysis of the SMTE flap equipped with an elephant trunk actuation mechanism. The morphing wing model was prototyped using a 3D printer. Four elephant trunk morphing ribs were embedded inside the flap section, all covered with a flexible skin. The control system for flap actuation was installed in the wing box corresponding to four elephant trunk mechanisms using an appropriate graphical interface to control the SMTE flap deflections. The completed model was further tested in a subsonic wind tunnel to validate the numerical aerodynamic results, as well as the functionality of the elephant trunk mechanism in real conditions. The results confirm the reliability and practicability of the proposed elephant trunk mechanism for actuation, and a very good agreement was obtained between the numerical aerodynamic data and wind tunnel test results. Full article

Drop-on-demand (DoD) printing is an additive manufacturing technique that utilizes functional inks containing nanoparticles (NPs) to fabricate electronic circuits or devices on a variety of substrates. One of the most promising applications for such technology is the aerospace industry, due to the capability of this method to fabricate custom low-weight geometric films. This work evaluates the performance of a gold (Au) nanoparticle (NP)-based film printed on a ceramic substrate for avionics applications, following the environmental temperature guidance of the Radio Technical Commission for Aeronautics (RTCA) DO-160. Experimental results show that the Au films, printed on alumina substrates, successfully survived the environmental temperature procedures for airborne equipment. The thermal coefficient of resistance (TCR) of the films was measured to be $2.7\times {10}^{-3} {°\mathrm{C}}^{-1}.$ Full article

A novel mechanism for seamless morphing trailing edge flaps is presented in this paper. This bio-inspired morphing concept is derived from an elephant’s trunk and is called the Elephant Trunk Mechanism (ETM). The structural flexibility of an elephant’s trunk and its ability to perform various types of deformations make it a promising choice in morphing technology for increasing the performance of continuous and smooth downward bending deformation at a trailing edge. This mechanism consists of a number of tooth-like elements attached to a solid wing box; the contractions of these tooth-like elements by external actuation forces change the trailing edge shape in the downwards direction. The main actuation forces are applied through wire ropes passing through tooth-like elements to generate the desired contractions on the flexible teeth. A static structural analysis using the Finite Element Method (FEM) is performed to examine this novel morphing concept and ensure its structural feasibility and stability. Topology optimization is also performed to find the optimum configuration with the objective of reducing the structural weight. The optimized mechanism is then attached to the flap section of a UAS-S45 wing. Finally, a skin analysis is performed to find its optimum skin material, which corresponds to the requirements of the morphing flap. The results of structural analysis and topology optimization reveal the reliability and stability of the proposed mechanism for application in the Seamless Morphing Trailing Edge (SMTE) flap. The optimization results led to significant improvements in the structural parameters, in addition to the desired weight reduction. The ETM maximum vertical displacement increased by 8.6%, while the von Mises stress decreased by 10.43%. Furthermore, the factor of safety improved from 1.3 to 1.5, thus indicating a safer design. The mass of the structure was reduced by 35.5%, achieving the primary goal of topology optimization. Full article

Complementary filters are commonly used in low-cost AHRS systems. This article presents an algorithm for selecting the time constant of a complementary filter for AHRS systems. The AHRS and complementary filtering principles of operation are described, followed by a methodology for calibrating the filter. A simple method for acquiring calibration data is introduced, and these data are subsequently used in the proposed iterative algorithm for optimal time constant selection. The described method minimizes measurement errors and improves the accuracy of the system, ensuring operational stability. For the synthesis, data are recorded in a static position of the system at various pitch and roll angles. Next, the optimal time constant of the complementary filter is determined. The statistical properties of the attitude angles are then analyzed. The proposed methodology for system assessment and analysis is discussed. Full article

The aviation industry significantly contributes to global greenhouse gas (GHG) emissions, accounting for approximately 2–3% of total annual CO₂ emissions, with high-altitude operations amplifying radiative forcing effects. This study quantitatively examines aviation’s contributions to global pollution compared to other transportation sectors, such as road and maritime, highlighting the substantial challenges in mitigating its environmental footprint. We focus on emissions of organic compounds, including polycyclic aromatic compounds and dioxins, and analyze key pollutants such as CO₂, NO_X, and ultrafine particles alongside the sector’s indirect effects. Our estimation indicates that dioxin emissions from commercial flights are negligible, at only 0.76 g annually; however, the sector’s broader impact on climate and air quality is significant. The analysis also evaluates current mitigation strategies, including the adoption of sustainable aviation fuels (SAFs), international initiatives like CORSIA, and advancements in aircraft technologies and operational efficiency. Despite these efforts, the projected growth in air traffic, estimated to increase annually by 5% over the next decade, underscores the urgent need for accelerated innovation and robust policy frameworks to achieve sustainable aviation. These findings emphasize the necessity of addressing aviation’s unique environmental challenges through international cooperation, technological advancements, and targeted climate actions. Full article

Deterministic Ethernet (DetEth) is widely used in real-time distributed systems, such as avionics and in-vehicle control. Clock synchronization protocols (CSPs) establish global time, which is a critical foundation for deterministic communication in DetEth. However, existing protocols often lack flexibility, making customization and adaptation to specific scenarios difficult and time consuming. We propose OpenSync, which is a software-defined clock synchronization architecture that decouples the synchronization control plane from the data plane. OpenSync includes a programmable time data injector and a fine-grained calibrated timer in the data plane, enabling easy implementation with standard DetEth hardware and support for various CSPs. The control plane provides a synchronization library to configure local clocks and retrieve accurate time data for different methods. To validate OpenSync’s generality and efficiency, we develop an FPGA-based prototype and implement three CSPs through software programming. A fully functional testbed demonstrates that these CSPs meet the accuracy and protocol consistency requirements of their respective application scenarios. Full article

Currently, relevant efforts are being dedicated to the implementation of Advanced Receiver Autonomous Integrity Monitoring (ARAIM) in future aviation receiver standards. These contributions focus on the specific aspects of algorithm processing and performance using simulated or real static user grid data. However, significant differences in the quality of measurements made by ground receivers compared to an avionics receiver may arise due to operational constraints such as space weather (troposphere and/or ionosphere), multipath, signal outages, and cycle slips. The objective of our work is to evaluate the Horizontal-ARAIM (H-ARAIM) reference algorithm sensitivity in an operational scenario using GPS and GALILEO dual-frequency flight data. Navigation performances are analyzed for typical arrival and approach maneuvers with respect to positioning accuracy and integrity for Required Navigation Performance (RNP) specifications, along with the evaluation of algorithm computational load when subjected to the dynamics of the aircraft. Full article

In azimuth sensing, aviation relies on the magnetic compass or magnetic sensors (flux valve, magnetometer) because the azimuth reference is Magnetic North. Maritime navigation completed the transition to True North. In October 2023, ICAO established the True North Advisory Group (True-AG) to consider the possibility of the same transition in aviation, as proposed by the International Association of Institutes of Navigation’s AHRTAG Group. There are significant benefits of this transition (accuracy, stability). Still, there are also some concerns and risks to be mitigated: the transition itself is a major change at the scale of the history of aviation, the need for an inexpensive basic sensor for True North, and other operational aspects. This paper analyses the azimuth sensing technology with a view on the transition to True North. This study comprises both general aviation and commercial aviation and concerns the integrity, accuracy, availability, and continuity of the azimuth flight parameter. The main True North sensors are the inertial reference system and the GNSS receiver. For a basic navigation sensor, the GNSS resilience is essential, and this is currently being challenged in many parts of the world in regions proximate to conflicts. Full article

This article presents a diagnostic system for two redundant AHRS units. The proposed system enables fault detection and identification, facilitating the design of more efficient flight control systems, particularly in low-cost applications. First, the principles of AHRS operation are first introduced, followed by a detailed description of the diagnostic system and the demonstration of the system’s properties. Simulation results presented in this article confirm the system’s effectiveness in fault detection and identification. The proposed solution can be applied in aeronautical control systems, particularly in UAV applications. Full article