Journal Description
Aerospace
Aerospace
is a peer-reviewed, open access journal of aeronautics and astronautics published monthly online by MDPI. The European Aeronautics Science Network (EASN), and the ECATS International Association are affiliated with Aerospace and their members receive a discount on the article processing charges.
- Open Access— free for readers, with article processing charges (APC) paid by authors or their institutions.
- High Visibility: indexed within Scopus, SCIE (Web of Science), Inspec, and other databases.
- Journal Rank: JCR - Q1 (Engineering, Aerospace) / CiteScore - Q2 (Aerospace Engineering)
- Rapid Publication: manuscripts are peer-reviewed and a first decision is provided to authors approximately 22.3 days after submission; acceptance to publication is undertaken in 2.7 days (median values for papers published in this journal in the second half of 2023).
- Recognition of Reviewers: reviewers who provide timely, thorough peer-review reports receive vouchers entitling them to a discount on the APC of their next publication in any MDPI journal, in appreciation of the work done.
- Companion journal: Astronomy.
Impact Factor:
2.6 (2022);
5-Year Impact Factor:
2.6 (2022)
Latest Articles
Ice Object Exclusion Characteristics of Turboshaft Engine Inlet under Helicopter/Inlet Integration Conditions
Aerospace 2024, 11(6), 458; https://doi.org/10.3390/aerospace11060458 - 5 Jun 2024
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In this study, the influence laws of different parameters on the exclusion characteristics of hailstone and ice flake, and on the aerodynamic performance of the inlet are studied by numerical method. The motion of the hailstone and ice flake is simulated using the
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In this study, the influence laws of different parameters on the exclusion characteristics of hailstone and ice flake, and on the aerodynamic performance of the inlet are studied by numerical method. The motion of the hailstone and ice flake is simulated using the 6-DOF method. Results show that the inhalation of hailstone in the inlet decreases total pressure distortion by about 20%, and the total pressure recovery coefficient is essentially unchanged. Icing of the upper lip decreases the total pressure distortion of the inlet by about 22%, and the total pressure recovery coefficient decreases by 0.6%. The ice flakes on the inner and outer lip, when shed and brake by collision with the center body, will cause damage to the engine duct. The shedding and breaking of ice flake at an angle of 150° to the lip can result in a large amount of ice flake debris entering the engine duct, threatening the performance and structure of the engine in the rear. The motion characteristics of hailstone and ice flake under helicopter fuselage/rotor/inlet integration conditions are revealed. It also provides a reference on the numerical methods for the numerical study of hailstone/ice flake exclusion characteristics of helicopter fuselage/rotor/inlet integration conditions.
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Robust Optimization Model of Airport Group Coordinated Timetable with Uncertain Flight Time
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Jianzhong Yan and Minghua Hu
Aerospace 2024, 11(6), 457; https://doi.org/10.3390/aerospace11060457 (registering DOI) - 5 Jun 2024
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This study develops a robust 0–1 linear optimization programming model for airport group timetable coordination, aiming at assigning each flight at an airport to a unique time slot to avoid conflicts between multiple flights from different airports at the same shared waypoint in
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This study develops a robust 0–1 linear optimization programming model for airport group timetable coordination, aiming at assigning each flight at an airport to a unique time slot to avoid conflicts between multiple flights from different airports at the same shared waypoint in an uncertain environment. Flight times between airports and shared waypoints are assumed to have an arbitrary distribution in the interval. Furthermore, some practical constraints, such as the time-varying capacity of each airport, waypoints affected by factors such as weather and traffic control, and maximum delay times for each flight, are considered in this study. The objective is to minimize the total delay time for all flights. The solution is obtained using the RSOME solver. Finally, a real-world case of the Beijing–Tianjin–Hebei airport group, China, is used to optimize the schedules of four airports to prove the accuracy and effectiveness of the method developed in this study. The influence of the budget of uncertainty parameters on model performance is also analyzed.
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Vision System for the Mars Sample Return Capture Containment and Return System (CCRS)
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Brent J. Bos, David L. Donovan, John I. Capone, Chen Wang, Terra C. Hardwick, Dylan E. Bell, Yuqing Zhu, Robert Podgurski, Bashar Rizk, Ireneusz Orlowski, Rachel A. Edison, David A. Harvey, Brianna Dizon, Lindsay Haseltine, Kristoffer C. Olsen, Chad Sheng, Robert R. Bousquet, Luan Q. Vo, Georgi T. Georgiev, Kristen A. Washington, Michael J. Singer, Stefan Ioana, Anloc H. Le, Elena M. Georgieva, Michael T. Hackett, Michael A. Ravine, Michael Caplinger, Phillip Coulter, Erin Percy, Charles Torisky, Jean-Marie Lauenstein, Kaitlyn L. Ryder, Michael J. Campola, Dillon E. Johnstone, William J. Thomes, Richard G. Schnurr, John C. McCloskey, Eugenia L. De Marco, Ellen Lee, Calinda M. Yew, Bo Yang, Mingyu Han and Bartosz Blonskiadd
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Aerospace 2024, 11(6), 456; https://doi.org/10.3390/aerospace11060456 - 5 Jun 2024
Abstract
The successful 2020 launch and 2021 landing of the National Aeronautics and Space Administration’s (NASA) Perseverance Mars rover initiated the first phase of the NASA and European Space Agency (ESA) Mars Sample Return (MSR) campaign. The goal of the MSR campaign is to
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The successful 2020 launch and 2021 landing of the National Aeronautics and Space Administration’s (NASA) Perseverance Mars rover initiated the first phase of the NASA and European Space Agency (ESA) Mars Sample Return (MSR) campaign. The goal of the MSR campaign is to collect scientifically interesting samples from the Martian surface and return them to Earth for further study in terrestrial laboratories. The MSR campaign consists of three major spacecraft components to accomplish this objective: the Perseverance Mars rover, the Sample Retrieval Lander (SRL) and the Earth Return Orbiter (ERO). Onboard the ERO spacecraft is the Capture, Containment and Return System (CCRS). CCRS will capture, process and return to Earth the samples that have been collected after they are launched into Mars orbit by the Mars Ascent Vehicle (MAV), which is delivered to Mars onboard the SRL. To facilitate the processing of the orbiting sample (OS) via the CCRS, we have designed and developed a vision system to determine the OS capture orientation. The vision system is composed of two cameras sensitive to the visible portion of the electromagnetic spectrum and two illumination modules constructed from broadband light emitting diodes (LED). Vision system laboratory tests and physics-based optical simulations predict CCRS ground processing will be able to correctly identify the OS post-capture orientation using only a single vision system image that is transmitted to Earth from Mars orbit.
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(This article belongs to the Special Issue Spacecraft Sample Collection)
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Detection of Precursors of Thermoacoustic Instability in a Swirled Combustor Using Chaotic Analysis and Deep Learning Models
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Boqi Xu, Zhiyu Wang, Hongwu Zhou, Wei Cao, Zhan Zhong, Weidong Huang and Wansheng Nie
Aerospace 2024, 11(6), 455; https://doi.org/10.3390/aerospace11060455 - 5 Jun 2024
Abstract
This paper investigates the role of chaotic analysis and deep learning models in combustion instability predictions. To detect the precursors of impending thermoacoustic instability (TAI) in a swirled combustor with various fuel injection strategies, a data-driven framework is proposed in this study. Based
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This paper investigates the role of chaotic analysis and deep learning models in combustion instability predictions. To detect the precursors of impending thermoacoustic instability (TAI) in a swirled combustor with various fuel injection strategies, a data-driven framework is proposed in this study. Based on chaotic analysis, a recurrence matrix derived from combustion system is used in deep learning models, which are able to detect precursors of TAI. More specifically, the ResNet-18 network model is trained to predict the proximity of unstable operation conditions when the combustion system is still stable. The proposed framework achieved state-of-the-art 91.06% accuracy in prediction performance. The framework has potential for practical applications to avoid an unstable operation domain in active combustion control systems and, thus, can offer on-line information on the margin of the combustion instability.
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(This article belongs to the Special Issue Advanced Flow Diagnostic Tools)
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Open AccessRetraction
RETRACTED: Eapen et al. A 6U CubeSat Platform for Low Earth Remote Sensing: DEWASAT-2 Mission Concept and Analysis. Aerospace 2023, 10, 815
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Ann Mary Eapen, Sidi Ahmed Bendoukha, Reem Al-Ali and Abdulrahman Sulaiman
Aerospace 2024, 11(6), 454; https://doi.org/10.3390/aerospace11060454 - 5 Jun 2024
Abstract
The Aerospace Editorial Office retracts and removes the article entitled “Eapen et al [...]
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Data Reduction Technologies in Prediction of Propeller Noise
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Samuel Afari and Reda Mankbadi
Aerospace 2024, 11(6), 453; https://doi.org/10.3390/aerospace11060453 - 4 Jun 2024
Abstract
High-fidelity computations are often used in predicting the tonal and broadband noise of propellers and rotors associated with Advanced Air Mobility Vehicles (AAMVs). But LES is both CPU and storage intensive. We present here an investigation of the feasibility of reduction methods such
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High-fidelity computations are often used in predicting the tonal and broadband noise of propellers and rotors associated with Advanced Air Mobility Vehicles (AAMVs). But LES is both CPU and storage intensive. We present here an investigation of the feasibility of reduction methods such as Proper Orthogonal Decomposition as well as Dynamic Mode Decomposition for reduction of data obtained via LES to be used further to obtain additional parameters. Specifically, we investigate how accurate reduced models of the high-fidelity computations can be used to predict the far-field noise. It is found that POD is capable of accurately reconstructing the parameters of interest with 15–40% of the total mode energies, whereas the DMD can only reconstruct primitive parameters such as velocity and pressure loosely. A rank truncation convergence criterion > 99.8% is needed for better performance of the DMD algorithm. In the far-field spectra, DMD can only predict the tonal contents in the lower and mid frequencies, while the POD can reproduce all frequencies of interest.
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(This article belongs to the Section Aeronautics)
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Study on the Influence of a Powered Nacelle on the Wake Vortex Characteristics of Wide-Body Aircraft
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Hexiang Wang, Junqiang Wu, Qiuting Guo, Guangyuan Liu, Jifei Wu, Dawei Liu, Yang Tao and Neng Xiong
Aerospace 2024, 11(6), 452; https://doi.org/10.3390/aerospace11060452 - 4 Jun 2024
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The aircraft wake vortex is an important factor affecting flight safety; as an important part of the aircraft, the powered nacelle will inevitably have an important impact on the aircraft wake vortex, so it is of great practical significance to research it. The
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The aircraft wake vortex is an important factor affecting flight safety; as an important part of the aircraft, the powered nacelle will inevitably have an important impact on the aircraft wake vortex, so it is of great practical significance to research it. The present study focused on the numerical simulation of the wake flow of large aircraft (as the front aircraft) and the comparative analysis of the influence of engine jets on the wake flow. In order to meet the accuracy requirements and control the consumption of computing resources, LES and RANS methods were compared, and the RANS method was finally selected for subsequent calculation. The dynamic effect of jet flow was simulated by simplifying the boundary conditions of the inlet fan and outlet bypass as the mass flow boundary condition. The simulation results showed that the engine nacelle will have a significant impact on the morphology of the aircraft wake flow (position and strength of the main vortex in the wake flow system), which is caused by the vortices formed under the shear flow and separated flow of the nacelle. However, the nacelle will not significantly change the total strength of the wake vortex (half-plane circulation). The engine jet intensity causes additional turbulent mixing, which will accelerate the fusion of the nacelle vortex and ultimately change the intensity ratio of the inner wing vortex and the wingtip vortex, affecting the trajectory of the wake of the mean vortex. The study provides a corresponding reference for the following research on a wake vortex by a powered nacelle.
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Operational Angular Track Reconstruction in Space Surveillance Radars through an Adaptive Beamforming Approach
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Marco Felice Montaruli, Maria Alessandra De Luca, Mauro Massari, Germano Bianchi and Alessio Magro
Aerospace 2024, 11(6), 451; https://doi.org/10.3390/aerospace11060451 - 1 Jun 2024
Abstract
In the last few years, many space surveillance initiatives have started to consider the problem represented by resident space object overpopulation. In particular, the European Space Surveillance and Tracking (EUSST) consortium is in charge of providing services like collision avoidance, fragmentation analysis, and
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In the last few years, many space surveillance initiatives have started to consider the problem represented by resident space object overpopulation. In particular, the European Space Surveillance and Tracking (EUSST) consortium is in charge of providing services like collision avoidance, fragmentation analysis, and re-entry, which rely on measurements obtained through ground-based sensors. BIRALES is an Italian survey radar belonging to the EUSST framework and is capable of providing measurements including Doppler shift, slant range, and angular profile. In recent years, the Music Approach for Track Estimate and Refinement (MATER) algorithm has been developed to retrieve angular tracks through an adaptive beamforming technique, guaranteeing the generation of more accurate and robust measurements with respect to the previous static beamforming approach. This work presents the design of a new data processing chain to be used by BIRALES to compute the angular track. The signal acquired by the BIRALES receiver array is down-converted and the receiver bandwidth is split into multiple channels, in order to maximize the signal-to-noise ratio of the measurements. Then, the signal passes through a detection block, where an isolation procedure creates, for each epoch, signal correlation matrices (CMs) related to the channels involved in the detection and then processes them to isolate the data stream related to a single detected source. Consequently, for each epoch and for each detected source, just the CM featuring the largest signal contribution is kept, allowing deriving the Doppler shift measurement from the channel illumination sequence. The MATER algorithm is applied to each CM stream, first estimating the signal directions of arrival, then grouping them in the observation time window, and eventually returning the target angular track. Ambiguous estimates may be present due to the configuration of the receiver array, which cause spatial aliasing phenomena. This problem can be addressed by either exploiting transit prediction (in the case of cataloged objects), or by applying tailored criteria (for uncatalogued objects). The performance of the new architecture was assessed in real operational scenarios, demonstrating the enhancement represented by the implementation of the channelization strategy, as well as the angular measurement accuracy returned by MATER, in both nominal and off-nominal scenarios.
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(This article belongs to the Special Issue Track Detection of Resident Space Objects)
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Pilot Assistance Systems for Energy-Optimized Approaches: Is It Possible to Reduce Fuel Consumption and Noise at the Same Time?
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Jean Marc Wunderli, Jonas Meister, Johan Boyer, Martin Gerber, Tobias Bauer and Fethi Abdelmoula
Aerospace 2024, 11(6), 450; https://doi.org/10.3390/aerospace11060450 - 1 Jun 2024
Abstract
Air traffic has appreciable environmental impacts, especially regarding gaseous emissions and noise. Recent studies have shown that the energy management during approach is a driving factor regarding environmental impact and is especially challenging for pilots. In a previous project, a newly developed pilot
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Air traffic has appreciable environmental impacts, especially regarding gaseous emissions and noise. Recent studies have shown that the energy management during approach is a driving factor regarding environmental impact and is especially challenging for pilots. In a previous project, a newly developed pilot assistance system called LNAS (Low Noise Augmentation System) showed the potential of energy-optimized approaches to reduce fuel consumption and noise. Within the SESAR Exploratory Research project DYNCAT, novel functions based on LNAS have been integrated in the flight management system. In this contribution, results from real-time simulations with the enhanced FMS are presented, and mitigation of the environmental impact is analyzed. It was shown that with DYNCAT, the energy management could be improved, resulting in a later configuration and engines mostly in idle. With DYNCAT, procedures were also flown more uniformly and the variability in noise and fuel outcomes was reduced. However, the results revealed a trade-off for optimizing noise and fuel consumption simultaneously, whereby both parameters can be improved along specific optimum curves. A perfect strategy to minimize noise would be to first reduce speed and only secondly height, as high speeds lead to higher levels of airframe noise and sound exposure increases with decreasing distance. In contrast, saving fuel might be achieved by reducing the flight time, as the engines consume fuel even when being in idle.
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(This article belongs to the Special Issue Multidisciplinary Design Optimization for Climate-Neutral Transport Aviation)
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Exploring the Aerodynamic Effect of Blade Gap Size via a Transient Simulation of a Four-Stage Turbine
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Xinlei Hu, Le Cai, Yingjie Chen, Xuejian Li, Songtao Wang, Xinglong Fang and Kanxian Fang
Aerospace 2024, 11(6), 449; https://doi.org/10.3390/aerospace11060449 - 1 Jun 2024
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With the impact of size on low-pressure turbines (LPTs) increasing, the gap between the blades has shrunk, inevitably influencing the unsteady effects inside the turbine. In this study, the aerodynamic effect of the blade gap size is investigated using a compressible unsteady Reynolds-averaged
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With the impact of size on low-pressure turbines (LPTs) increasing, the gap between the blades has shrunk, inevitably influencing the unsteady effects inside the turbine. In this study, the aerodynamic effect of the blade gap size is investigated using a compressible unsteady Reynolds-averaged Navier–Stokes (URANS) model on the basis of a four-stage LPT. Simulations are conducted in which the gap between the third-stage stator (S3) and rotor (R3) varies from 0.2 to 0.8 times the axial chord length of the R3 blade. The multi-stage environment reflects the complexity of real low-Reynolds flow fields. Computational fluid dynamics is used to analyze the flow field in detail. The results demonstrate that in the small-gap (AG-0.2) case, the turbulence kinetic energy (TKE) level of the S3 wake close to the R3 leading edge is four-thirds of that in the large-gap (AG-0.8) case. The higher intensity of the wake impacting on the blade results in a higher inverse pressure gradient in the rear part of the R3 suction surface, which increases the profile loss. However, the AG-0.2 case leads to fewer losses caused by the passage vortex in the hub area under the influence of the higher intensity of the wake.
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Multi-Fidelity Adaptive Sampling for Surrogate-Based Optimization and Uncertainty Quantification
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Andrea Garbo, Jigar Parekh, Tilo Rischmann and Philipp Bekemeyer
Aerospace 2024, 11(6), 448; https://doi.org/10.3390/aerospace11060448 - 31 May 2024
Abstract
Surrogate-based algorithms are indispensable in the aerospace engineering field for reducing the computational cost of optimization and uncertainty quantification analyses, particularly those involving computationally intensive solvers. This paper presents a novel approach for enhancing the efficiency of surrogate-based algorithms through a new multi-fidelity
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Surrogate-based algorithms are indispensable in the aerospace engineering field for reducing the computational cost of optimization and uncertainty quantification analyses, particularly those involving computationally intensive solvers. This paper presents a novel approach for enhancing the efficiency of surrogate-based algorithms through a new multi-fidelity sampling technique. Unlike existing multi-fidelity methods which are based on a single multiplicative acquisition function, the proposed technique decouples the identification of the new infill sample from the selection of the fidelity level. The location of the infill sample is determined by leveraging the highest fidelity surrogate model, while the fidelity level used for its performance evaluation is chosen as the cheapest one within the “accurate enough” models at the infill location. Moreover, the methodology introduces the application of the Jensen–Shannon divergence to quantify the accuracy of the different fidelity levels. Overall, the resulting technique eliminates some of the drawbacks of existing multiplicative acquisition functions such as the risk of continuous sampling from lower and cheaper fidelity levels. Experimental validation conducted in surrogate-based optimization and uncertainty quantification scenarios demonstrates the efficacy of the proposed approach. In an aerodynamic shape optimization task focused on maximizing the lift-to-drag ratio, the multi-fidelity strategy achieved comparable results to standard single-fidelity sampling but with approximately a five-fold improvement in computational efficiency. Likewise, a similar reduction in computational costs was observed in the uncertainty quantification problem, with the resulting statistical values aligning closely with those obtained using traditional single-fidelity sampling.
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(This article belongs to the Special Issue Data-Driven Aerodynamic Modeling)
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Built On-Orbit Robotically Assembled Gigatruss (BORG): Ground Robotic Demonstration
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Samantha Chapin, Holly Everson, William Chapin and Erik Komendera
Aerospace 2024, 11(6), 447; https://doi.org/10.3390/aerospace11060447 - 31 May 2024
Abstract
The next generation of large space infrastructure will require crucial advancements in current technology. Current methodologies focus on large deployable structures folded into cramped payload fairings or revolutionary assembly techniques requiring many moving components. Utilizing both in-space assembly and deployable concepts, a hybrid
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The next generation of large space infrastructure will require crucial advancements in current technology. Current methodologies focus on large deployable structures folded into cramped payload fairings or revolutionary assembly techniques requiring many moving components. Utilizing both in-space assembly and deployable concepts, a hybrid mixed assembly scheme was posed using smaller deployable units interspersed with rigid connecting elements to assemble these large architectures. The Built On-Orbit Robotically Assembled Gigatruss (BORG) structure allows for modularity in assembly and repair with the number of separate elements comprising the structure to be reduced, compared to strut-by-strut assembly. The following documents the process of constructing and running physical trials on a prototype BORG architecture. Additionally, a Semantic and Fiducial Aided Graph Simultaneous Localization and Mapping (SF-GraphSLAM) approach is taken to verify the relation of assembled and deployed truss elements to aid in error evaluation and state estimation. This technology demonstration stands as a proof of concept in verifying the viability of the BORG architecture as a method for large structure assembly.
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(This article belongs to the Special Issue Advanced Spacecraft/Satellite Technologies)
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The Derivation of an Empirical Model to Estimate the Power Spectral Density of Turbulent Boundary Layer Wall Pressure in Aircraft Using Machine Learning Regression Techniques
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Zachary Huffman and Joana Rocha
Aerospace 2024, 11(6), 446; https://doi.org/10.3390/aerospace11060446 - 31 May 2024
Abstract
Aircraft cabin noise poses a health risk for regular passengers and crew, being connected to a heightened risk of cardiovascular disease, hearing loss, and sleep deprivation. At cruise conditions, its most significant cause is random pressure fluctuations in the turbulent boundary layer of
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Aircraft cabin noise poses a health risk for regular passengers and crew, being connected to a heightened risk of cardiovascular disease, hearing loss, and sleep deprivation. At cruise conditions, its most significant cause is random pressure fluctuations in the turbulent boundary layer of aircraft, and as such the derivation of an accurate model to predict the power spectral density of these fluctuations remains an important ongoing research topic. Early models (such as those by Lowson and Robertson) were derived by simplifying the governing equations, the Reynolds-averaged Navier Stokes equations, and solving for fluctuating pressure. Most subsequent equations were derived either by applying statistical and mathematical techniques to simplify the Robertson and Lowson models or by making modifications to address apparent shortcomings. Overall, these models have had varying success—most are accurate near the Mach and Reynolds numbers they were designed for, but less accurate under other conditions. In response to this shortcoming, Dominique demonstrated that a novel technique (machine learning, specifically artificial neural networking) could produce a model that is accurate under most flight conditions. This paper extends this research further by applying a different machine learning technique (nonlinear least squares regression analysis) and dimensional analysis to produce a new model. The resulting equation proved accurate under its design conditions of low airspeed (approximately 11 m/s) and low turbulent Reynolds number (approximately 850,000). However, a larger dataset with more diverse flight conditions would be required to make the model more generally applicable.
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(This article belongs to the Topic Advances in Underwater Acoustics and Aeroacoustics)
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Identification and Analysis of Flight Delay Based on Process Relevance
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Qingmiao Ding, Linyan Ma, Yanyu Cui, Bin Cheng and Xuan He
Aerospace 2024, 11(6), 445; https://doi.org/10.3390/aerospace11060445 - 31 May 2024
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Flight delay identification is an important way to coordinate the operation time of airport ground service providers and improve the efficiency of airport operations. By analyzing the flight turnaround operation process, considering the randomness and synchronization of the turnaround process, and using Colored
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Flight delay identification is an important way to coordinate the operation time of airport ground service providers and improve the efficiency of airport operations. By analyzing the flight turnaround operation process, considering the randomness and synchronization of the turnaround process, and using Colored Petri Nets and Python (4.0.1), we explore the correlation between various links in the flight turnaround process and the take-off delay at the next station. This paper is committed to improving the service performance of airports and airlines, dynamically predicting flight delays, and providing guidance for avoiding excessive time in the actual operation of bad combinations. The results show that there are six kinds of bad combinations in the departure slip-out link, which is the most likely to affect the transit time. The maximum lifting degree in the bad combination is 2.043, and the maximum average delay time in the bad combination is 22.5 min. When the combination of passenger boarding and departure slip-out time is too long, it has a great positive correlation with delay. When the other links are in a state of being able to pass the station on time, the departure time and baggage loading and unloading are the two links that most affect the flight delay value.
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Open AccessArticle
Negative Medium-Voltage Direct Current Discharges in Air under Simulated Sub-Atmospheric Pressures for All-Electric Aircraft
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Sai Pavan Kalakonda, Mohammad Hamidieh, Adil Bhojwani and Mona Ghassemi
Aerospace 2024, 11(6), 444; https://doi.org/10.3390/aerospace11060444 - 30 May 2024
Abstract
The increase in the global temperature due to greenhouse gas emissions is a major concern to the world. To achieve the goal of zero emissions by 2050 in the USA the practical realization of all-electric vehicles, particularly all-electric aircraft (AEA), is important. For
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The increase in the global temperature due to greenhouse gas emissions is a major concern to the world. To achieve the goal of zero emissions by 2050 in the USA the practical realization of all-electric vehicles, particularly all-electric aircraft (AEA), is important. For the design of electrical power systems (EPSs) in all-electric aircraft, a bipolar medium-voltage direct current (MVDC) system of ±5 kV is being investigated. However, several challenges manifest when using such voltages in a low-pressure environment. One of the main challenges is the partial discharge (PD) behavior of the insulation. It is important to study the PD behavior of the insulation by simulating the aviation environment in the lab. This work aimed to study the partial discharge behavior of air under a negative DC voltage in a needle-to-plane electrode geometry by simulating the aviation pressures in the lab. The partial discharge inception voltage (PDIV) and the breakdown voltage (BDV) show an obvious pressure-dependent variation. Regression analysis was performed to better understand the relationship between the PDIV and pressures. Plots were drawn for the average discharge current at each voltage step until breakdown. This paper’s findings can provide valuable insight into the design of EPS for an AEA. To the best of our knowledge, such a study has not been carried out to date.
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(This article belongs to the Special Issue Electric Power Systems and Components for All-Electric Aircraft)
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Orbital Pursuit–Evasion–Defense Linear-Quadratic Differential Game
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Zhen-Yu Li
Aerospace 2024, 11(6), 443; https://doi.org/10.3390/aerospace11060443 - 30 May 2024
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To find superior guidance strategies for preventing possible interception threats from space debris, out-of-control satellites, etc., this paper investigates an orbital pursuit–evasion–defense game problem with three players called the pursuer, the evader, and the defender, respectively. In this game, the pursuer aims to
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To find superior guidance strategies for preventing possible interception threats from space debris, out-of-control satellites, etc., this paper investigates an orbital pursuit–evasion–defense game problem with three players called the pursuer, the evader, and the defender, respectively. In this game, the pursuer aims to intercept the evader, while the evader tries to escape the pursuer. A defender accompanying the evader can protect the evader by actively intercepting the pursuer. For such a game, a linear-quadratic duration-adaptive (LQDA) strategy is first proposed as a basic strategy for the three players. Later, an advanced pursuit strategy is designed for the pursuer to evade the defender when they are chasing the evader. Meanwhile, a cooperative evasion–defense strategy is proposed for the evader and the defender to build their cooperation. Simulations determined that the proposed LQDA strategy has higher interception accuracy than the classic LQ strategy. Meanwhile, the proposed two-sided pursuit strategy can improve the interception performance of the pursuer against a non-cooperative defender. But if the evader and defender employ the proposed cooperation strategy, the pursuer’s interception will be much more difficult.
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Open AccessArticle
Activity Modeling and Characterization for Airport Bird Situation Awareness Using Avian Radar Datasets
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Jia Liu, Qunyu Xu, Min Su and Weishi Chen
Aerospace 2024, 11(6), 442; https://doi.org/10.3390/aerospace11060442 - 30 May 2024
Abstract
Birds in airport airspaces are critical threats to aviation safety. Avian radar systems are effective for long-range bird monitoring and hazard warning, but their functionalities are confined to a short-term temporal scale. Spatial–temporal activity modeling and characterization for birds are not studied comprehensively
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Birds in airport airspaces are critical threats to aviation safety. Avian radar systems are effective for long-range bird monitoring and hazard warning, but their functionalities are confined to a short-term temporal scale. Spatial–temporal activity modeling and characterization for birds are not studied comprehensively from historical radar datasets. This paper proposes a radar data analysis framework to characterize bird activities as a long-term functionality complement. Spatial domain modeling initializes data mining by extracting reference spots for data filtering. Bird activities are quantified in the temporal domain. Activity degrees are utilized for periodicity extraction with the daily segment random permutation strategy. Categorical probabilities are calculated to interpret bird activity periodicity characters. Historical radar datasets collected from an avian radar system are adopted for validation. The extracted activity periodicity trends for diurnal birds present prominent consistency with artificial observation records. Migratory bird periodicity trends present a good match with ornithology understandings. A preliminary experiment is presented to indicate the possibility of predicting bird activity levels, especially for migratory birds.
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(This article belongs to the Special Issue Advances in Air Traffic and Airspace Control and Management (2nd Edition))
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Exploring the Psychological Well-Being of Flight Cadets through a Comprehensive Survey Analysis of Self-Awareness and Self-Acceptance
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Dan Miao, Xiaodong Cao, Bingxu Zhao, Yuan Shi and Yunze Shi
Aerospace 2024, 11(6), 441; https://doi.org/10.3390/aerospace11060441 - 30 May 2024
Abstract
A robust level of self-awareness and self-acceptance is crucial for flight cadets. In this study, a total of 106 flight cadets from various grades and flight training sites were assessed using the self-awareness and self-acceptance scale. The scales were optimized through item analysis,
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A robust level of self-awareness and self-acceptance is crucial for flight cadets. In this study, a total of 106 flight cadets from various grades and flight training sites were assessed using the self-awareness and self-acceptance scale. The scales were optimized through item analysis, reliability, and validity assessments. The finalized scales demonstrated an acceptable level of reliability and validity. Upon analyzing the collected data, it was observed that the overall self-awareness and -acceptance levels among the evaluated pilot students fell within the normal range. However, identifying positive symptoms directly proved challenging. The tested flight cadets exhibited moderate symptoms across each factor, with instances of severe symptoms in academic self-awareness. Notably, flight cadets trained abroad exhibited a lower level of self-awareness and -acceptance compared to those trained in China. But this phenomenon was not reflected in grade difference. Regression analysis revealed that physical and emotional self-awareness dimensions accounted for 62% of the variations in the psychological dimension, while passive self-acceptance explained 72% of the changes in active self-acceptance. Finally, in view of the issues found in the research, corresponding management measures and recommendations are presented to enhance the self-awareness and -acceptance levels of flight cadets.
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(This article belongs to the Special Issue Aerospace Human–Machine and Environmental Control Engineering)
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Open AccessArticle
Modeling and Analysis of the Flap Actuation System Considering the Nonlinear Factors of EMA, Joint Clearance and Flexibility
by
Qi Wan, Chunyu Song, Yong Zhou, Ruiting Tong, Shangjun Ma and Geng Liu
Aerospace 2024, 11(6), 440; https://doi.org/10.3390/aerospace11060440 - 29 May 2024
Abstract
The performance of the flap actuation system directly affects the control effect and the flight quality of an aircraft. The electromechanical actuator (EMA) and the linkage mechanism are important components of the system. In order to achieve the goals of good transmission accuracy
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The performance of the flap actuation system directly affects the control effect and the flight quality of an aircraft. The electromechanical actuator (EMA) and the linkage mechanism are important components of the system. In order to achieve the goals of good transmission accuracy and dynamic response, the influence of nonlinear properties in the transmission chain including the EMA and linkage mechanism should be considered. A co-simulation model at the system-level of the flap actuation system was developed, which takes nonlinear factors of the EMA, the impact dynamics of the linkage mechanism with joint clearance and the rigid–flexible coupling characteristics into account. Moreover, the experiments with different command frequencies and loads were performed. The simulation and experimental results were compared to verify the effectiveness of the co-simulation model. Finally, the effects of nonlinear properties including the contact stiffness and clearance of a planetary roller screw mechanism, EMA anchorage stiffness, number of clearance joints, flexibility and load are discussed. This work can contribute to analyzing the performance of an electromechanical multibody system with nonlinear characteristics, which has crucial academic meaning and engineering application values for the development of systems with high speed, good reliability and long life.
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(This article belongs to the Section Aeronautics)
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Instrument to Study Plume Surface Interactions (PSI) on the Lunar Surface: Science Motivation, Requirements, Instrument Overview, and Test Plans
by
Ariana Bueno, Michael J. Krasowski, Norman Prokop, Lawrence C. Greer, Christina M. Adams and Nilton O. Rennó
Aerospace 2024, 11(6), 439; https://doi.org/10.3390/aerospace11060439 - 29 May 2024
Abstract
Safe landings are imperative to accomplish NASA’s Artemis goal to enable human exploration on the Moon, including sample collection missions. However, a process known as plume surface interaction (PSI) presents a significant hazard to lunar landings. PSI occurs when the engine exhaust of
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Safe landings are imperative to accomplish NASA’s Artemis goal to enable human exploration on the Moon, including sample collection missions. However, a process known as plume surface interaction (PSI) presents a significant hazard to lunar landings. PSI occurs when the engine exhaust of a lander interacts with the surface ejecting large amounts of regolith particles at high velocities that can interfere with the landing, disturb the surface, and damage hardware. To better understand PSI, the particle impact event (PIE) sensor is being developed to measure the kinetic energy and the flux of ejecta during landings, to quantify the potential damage, and to quantify the ejecta displaced. Multiple parameters were estimated to define the PIE instrument requirements. These estimates demonstrate that ejecta can travel at velocities of up to 800 m/s and impact the surrounding area with energies of up to 400 µJ. A significant amount of ejecta can be deposited several 10 s of meters away from the landing site, modifying the surface and causing dust-related challenges. The PIE sensor will be launched for the first time in an upcoming lunar lander. Then, PIE measurements will be used to improve PSI prediction capabilities and develop mitigation strategies to ensure safe landings.
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(This article belongs to the Special Issue Spacecraft Sample Collection)
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