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Aerospace, Volume 10, Issue 1 (January 2023) – 90 articles

Cover Story (view full-size image): An adaptive deep transfer learning scheme is proposed for aircraft engine health prognosis under time-varying real flight conditions, which is usually a challenge in terms of data unavailability, complexity, and drift. Adaptive learning encapsulates long short-term memory to tackle data drift issues resulting in a massive change in data characteristics. Meanwhile, deep transfer learning adopts a pre-trained network over a sufficient number of degradation trajectories generated from health deterioration analysis software. The outcome is an excellent combination for overcoming data unavailability and complexity. This combination is used on the new commercial modular aero-propulsion system simulation dataset released by NASA, which exactly meets these criteria. The designed model, evaluated on several measures and visual interpretations, strongly supports the design results. View this paper
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19 pages, 4726 KiB  
Article
Application of Model-Free Control to the Operation of Post-Capture Combined Spacecraft
by Ting Song, Zixuan Zheng, Yufei Guo and Jianping Yuan
Aerospace 2023, 10(1), 90; https://doi.org/10.3390/aerospace10010090 - 16 Jan 2023
Cited by 2 | Viewed by 1591
Abstract
A model-free control method is applied to the attitude and orbital operation of the post-capture combined spacecraft, which consists of a space robot and debris. The main contribution of this paper lies in the following three aspects. Firstly, the discrete dynamic linearization method [...] Read more.
A model-free control method is applied to the attitude and orbital operation of the post-capture combined spacecraft, which consists of a space robot and debris. The main contribution of this paper lies in the following three aspects. Firstly, the discrete dynamic linearization method of the motion equation for a post-capture combined spacecraft is proposed, and then, the standardized expression form of multiple input and multiple output system for the attitude and orbital dynamics motions of post-capture combined spacecraft are presented. Secondly, the data mapping model of the post-capture combined spacecraft is defined, and based on this, an initial value online optimization method for the data mapping model is provided, which is key for the convergence of model-free control. Finally, a test system based on the ground-based three-axis spacecraft simulator is built to simulate the attitude and orbital operation of post-capture combined spacecraft, and the experimental system is implemented to verify the validation of the model-free control method proposed in this paper. The results show that the model-free control has a good control effect on the attitude and orbit of the post-capture combined spacecraft, even if the configuration of the spacecraft is time-varying. Full article
(This article belongs to the Special Issue Emerging Space Missions and Technologies)
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14 pages, 5882 KiB  
Article
Two-Stage Intelligent Layout Design of Curved Cabin Door
by Tianhe Gao, Ziyu Xu, Zengcong Li, Pei Liu and Kuo Tian
Aerospace 2023, 10(1), 89; https://doi.org/10.3390/aerospace10010089 - 16 Jan 2023
Cited by 2 | Viewed by 1774
Abstract
As one of the most complex and critical components of spacecraft, the structural design of the curved cabin door faces two challenges. On the one hand, it is difficult to obtain innovative configurations for the cabin door in the preliminary design stage. On [...] Read more.
As one of the most complex and critical components of spacecraft, the structural design of the curved cabin door faces two challenges. On the one hand, it is difficult to obtain innovative configurations for the cabin door in the preliminary design stage. On the other hand, the traditional optimization design algorithm is inefficient in the detailed design stage. In this paper, a two-stage intelligent method for the layout design of the curved cabin door is proposed. In the first stage, the innovative stiffener layout of the cabin door is obtained based on the topology optimization method. Then the mesh deformation method is used for rapid modeling and geometric reconstruction. In the second stage, a recently proposed powerful evolutionary algorithm, named elite-driven surrogate-assisted Covariance Matrix Adaptation Evolution Strategy (ES-CMA-ES), is employed to optimize the parameters of the cabin door and its surrounding thin-wall structure. To verify the effectiveness of the proposed method, a curved cabin door example from the spacecraft (cargo spaceship) is carried out. Compared with the traditional orthogrid stiffener design, the mass of the optimal design is reduced by 52.21% while satisfying the constraints, which indicates the excellent optimization ability of the proposed method and demonstrates huge potential for improving the carrying capacity and efficiency of the spacecraft. Full article
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19 pages, 803 KiB  
Article
Automated Model Hardening with Reinforcement Learning for On-Orbit Object Detectors with Convolutional Neural Networks
by Qi Shi, Lu Li, Jiaqi Feng, Wen Chen and Jinpei Yu
Aerospace 2023, 10(1), 88; https://doi.org/10.3390/aerospace10010088 - 16 Jan 2023
Cited by 1 | Viewed by 2462
Abstract
On-orbit object detection has received extensive attention in the field of artificial intelligence (AI) in space research. Deep-learning-based object-detection algorithms are often computationally intensive and rely on high-performance devices to run. However, those devices usually lack space-qualified versions, and they can hardly meet [...] Read more.
On-orbit object detection has received extensive attention in the field of artificial intelligence (AI) in space research. Deep-learning-based object-detection algorithms are often computationally intensive and rely on high-performance devices to run. However, those devices usually lack space-qualified versions, and they can hardly meet the reliability requirement if directly deployed on a satellite platform, due to software errors induced by the space environment. In this paper, we evaluated the impact of space-environment-induced software errors on object-detection algorithms through large-scale fault injection tests. Aside from silent data corruption (SDC), we propose an extended criterial SDC-0.1 to better quantify the effect of the transient faults on the object-detection algorithms. Considering that a bit-flip error could cause severe detection result corruption in many cases, we propose a novel automated model hardening with reinforcement learning (AMHR) framework to solve this problem. AMHR searches for error-sensitive kernels in a convolutional neural network (CNN) through trial and error with a deep deterministic policy gradient (DDPG) agent and has fine-grained modular-level redundancy to increase the fault tolerance of the CNN-based object detectors. Compared to other selective hardening methods, AMHR achieved the lowest SDC-0.1 rates for various detectors and could tremendously improve the mean average precision (mAP) of the SSD detector by 28.8 in the presence of multiple errors. Full article
(This article belongs to the Special Issue Advances in Aerospace Software Engineering)
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14 pages, 4017 KiB  
Article
Correlation between Density of Reentry Plasma and Frequency of Attenuated Electromagnetic Signals Based on Laboratory Measurements
by Gi-Won Shin, Jae-Hyeon Kim, Sun-Hee Lee, In-Young Bang, Ji-Hwan Kim, Yeon-Soo Park, Hee-Tae Kwon, Woo-Jae Kim and Gi-Ching Kwon
Aerospace 2023, 10(1), 87; https://doi.org/10.3390/aerospace10010087 - 15 Jan 2023
Viewed by 1705
Abstract
Upon reentering the Earth’s atmosphere from space, a reentry vehicle becomes enshrouded in an ionization layer. This layer is known as the reentry plasma sheath and is caused by aerodynamic heating. Owing to the oscillation of charged particles in the reentry plasma sheath, [...] Read more.
Upon reentering the Earth’s atmosphere from space, a reentry vehicle becomes enshrouded in an ionization layer. This layer is known as the reentry plasma sheath and is caused by aerodynamic heating. Owing to the oscillation of charged particles in the reentry plasma sheath, the electromagnetic waves for communication between the vehicle and ground are attenuated. Analysis of the plasma density and attenuation of electromagnetic waves in a reentry plasma environment would require experimentation in an environment in which an actual aircraft reenters the atmosphere. Alternatively, an experiment in a large-scale plasma wind tunnel would be necessary. Unfortunately, these experiments would be extremely costly. Therefore, in this study, the reentry plasma was reproduced at laboratory scale using the hot refractory anode vacuum arc (HRAVA) method. In addition, the pressure in the vacuum chamber was used as a variable to probe the characteristics of the reentry plasma according to the altitude. The plasma density and attenuation of electromagnetic waves propagating through the plasma medium were measured using heterodyne interferometry and reflectometry capable of frequency analysis in the range of 10−35 GHz. The results confirmed that the plasma density and attenuation of the electromagnetic waves increased as the pressure in the vacuum chamber increased. Full article
(This article belongs to the Section Astronautics & Space Science)
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16 pages, 3237 KiB  
Article
Intelligent Pursuit–Evasion Game Based on Deep Reinforcement Learning for Hypersonic Vehicles
by Mengjing Gao, Tian Yan, Quancheng Li, Wenxing Fu and Jin Zhang
Aerospace 2023, 10(1), 86; https://doi.org/10.3390/aerospace10010086 - 15 Jan 2023
Cited by 2 | Viewed by 2493
Abstract
As defense technology develops, it is essential to study the pursuit–evasion (PE) game problem in hypersonic vehicles, especially in the situation where a head-on scenario is created. Under a head-on situation, the hypersonic vehicle’s speed advantage is offset. This paper, therefore, establishes the [...] Read more.
As defense technology develops, it is essential to study the pursuit–evasion (PE) game problem in hypersonic vehicles, especially in the situation where a head-on scenario is created. Under a head-on situation, the hypersonic vehicle’s speed advantage is offset. This paper, therefore, establishes the scenario and model for the two sides of attack and defense, using the twin delayed deep deterministic (TD3) gradient strategy, which has a faster convergence speed and reduces over-estimation. In view of the flight state–action value function, the decision framework for escape control based on the actor–critic method is constructed, and the solution method for a deep reinforcement learning model based on the TD3 gradient network is presented. Simulation results show that the proposed strategy enables the hypersonic vehicle to evade successfully, even under an adverse head-on scene. Moreover, the programmed maneuver strategy of the hypersonic vehicle is improved, transforming it into an intelligent maneuver strategy. Full article
(This article belongs to the Special Issue Learning-Based Intelligent Control in Aerospace Applications)
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24 pages, 8786 KiB  
Article
Experimental Assessment of Aero-Propulsive Effects on a Large Turboprop Aircraft with Rear-Engine Installation
by Salvatore Corcione, Vincenzo Cusati, Danilo Ciliberti and Fabrizio Nicolosi
Aerospace 2023, 10(1), 85; https://doi.org/10.3390/aerospace10010085 - 15 Jan 2023
Viewed by 1730
Abstract
This paper deals with the estimation of propulsive effects for a three-lifting surface turboprop aircraft concept, with rear engine installation at the horizontal tail tips, conceived to carry up to 130 passengers. This work is focused on how the propulsive system affects the [...] Read more.
This paper deals with the estimation of propulsive effects for a three-lifting surface turboprop aircraft concept, with rear engine installation at the horizontal tail tips, conceived to carry up to 130 passengers. This work is focused on how the propulsive system affects the horizontal tailplane aerodynamics and, consequently, the aircraft’s static stability characteristics using wind tunnel tests. Both direct and indirect propulsive effects have been estimated. The former produces moments whose values depend on the distance from the aircraft’s centre of gravity to the thrust lines and propeller disks. The latter entails a change in the angle of attack and an increment of dynamic pressure on the tailplane. Several tests were also performed on the body-empennage configuration to investigate the propulsive effects on the aircraft’s static stability without the appearance of any aerodynamic interference phenomena, especially from the canard. The output of the experimental campaign reveals a beneficial effect of the propulsive effects on the aircraft’s longitudinal stability, with an increase in the stability margin of about 2.5% and a reduction in the directional stability derivative of about 4%, attributed to the different induced drag contributions of the two horizontal tail semi-planes. Moreover, the rolling moment coefficient experiences a greater variation due to the propulsion depending on the propeller rotation direction. The outcomes of this paper allow the enhancement of the technical readiness level for the considered aircraft, giving clear indications about the feasibility of the aircraft configuration. Full article
(This article belongs to the Special Issue Turboprop Aircraft Design and Optimization)
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22 pages, 21440 KiB  
Article
Automatic Marine Debris Inspection
by Yu-Hsien Liao and Jih-Gau Juang
Aerospace 2023, 10(1), 84; https://doi.org/10.3390/aerospace10010084 - 14 Jan 2023
Viewed by 1346
Abstract
Plastic trash can be found anywhere, around the marina, beaches, and coastal areas in recent times. This study proposes a trash dataset called HAIDA and a trash detector that uses a YOLOv4-based object detection algorithm to monitor coastal trash pollution efficiently. Model selection, [...] Read more.
Plastic trash can be found anywhere, around the marina, beaches, and coastal areas in recent times. This study proposes a trash dataset called HAIDA and a trash detector that uses a YOLOv4-based object detection algorithm to monitor coastal trash pollution efficiently. Model selection, model evaluation, and hyperparameter tuning were applied to obtain the best model for the lowest generalization error in the real world. Comparison of the state-of-the-art object detectors based on YOLOv3, YOLOv4, and Scaled-YOLOv4 that used hyperparameter tuning, the three-way holdout method, and k-fold cross-validation have been presented. An unmanned aerial vehicle (UAV) was also employed to detect trash in coastal areas using the proposed method. The performance on image classification was satisfactory. Full article
(This article belongs to the Special Issue Applications of Drones)
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18 pages, 6521 KiB  
Article
Determination of the Parachute Harness Critical Load Based on Load Distribution into Individual Straps with Respect of the Skydiver’s Body Position
by Robert Grim, Robert Popela, Ivo Jebáček, Marek Horák and Jan Šplíchal
Aerospace 2023, 10(1), 83; https://doi.org/10.3390/aerospace10010083 - 14 Jan 2023
Viewed by 2251
Abstract
This article evaluates the redistribution of forces to the parachute harness during an opening shock load and also defines the ultimate limit load of the personal parachute harness by specifying the weakest construction element and its load capacity. The primary goal of this [...] Read more.
This article evaluates the redistribution of forces to the parachute harness during an opening shock load and also defines the ultimate limit load of the personal parachute harness by specifying the weakest construction element and its load capacity. The primary goal of this research was not only to detect the critical elements but also to gain an understanding of the force redistribution at various load levels, which could represent changes in body mass or aerodynamic properties of the parachute during the opening phase. To capture all the phenomena of the parachutist’s body deceleration, this study also includes loading the body out of the steady descending position and asymmetrical cases. Thus, the result represents not only idealized loading but also realistic limit cases, such as asymmetric canopy inflation or system activation when the skydiver is in a non-standard position. The results revealed a significant difference in the strength utilization of the individual components. Specifically, the back webbing was found to carry a fractional load compared to the other webbing used in the design in most of the scenarios tested. Reaching the maximum allowable strength was first achieved in the asymmetric load test case, where the total force would be equal to the value of 7.963 kN, which corresponds to the maximum permissible strength of the carabiner on the measuring element three. In the same test case, the second weakest point would reach the limiting load force when the entire harness is loaded with 67.89 kN. This information and the subsequent analysis of the individual nodes provide a great opportunity for further strength and weight optimization of the design, without reducing the load capacity of the harness as a system. The findings of this study will be used for further testing and possible harness robustness optimization for both military and sport parachuting. Full article
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21 pages, 87236 KiB  
Article
Quadcopter Drone for Vision-Based Autonomous Target Following
by Wen-Chieh Chen, Chun-Liang Lin, Yang-Yi Chen and Hsin-Hsu Cheng
Aerospace 2023, 10(1), 82; https://doi.org/10.3390/aerospace10010082 - 14 Jan 2023
Cited by 2 | Viewed by 3666
Abstract
Unmanned aerial vehicles (UAVs) are becoming popular in various applications. However, there are still challenging issues to be tackled, such as effective obstacle avoidance, target identification within a crowd, and specific target tracking. This paper focuses on dynamic target following and obstacle avoidance [...] Read more.
Unmanned aerial vehicles (UAVs) are becoming popular in various applications. However, there are still challenging issues to be tackled, such as effective obstacle avoidance, target identification within a crowd, and specific target tracking. This paper focuses on dynamic target following and obstacle avoidance to realize a prototype of a quadcopter drone to serve as an autonomous object follower. An adaptive target identification system is proposed to recognize the specific target in the complicated background. For obstacle avoidance during flight, we introduce an idea of space detection and use it to develop a so-called contour and spiral convolution space detection (CASCSD) algorithm to evade obstacles. Thanks to the low architecture complexity, it is appropriate for implementation on onboard flight control systems. The target prediction is integrated with fuzzified flight control to fulfill an autonomous target tracker. When this series of technical research and development is completed, this system can be used for applications such as personal security guard and criminal detection systems. Full article
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24 pages, 4361 KiB  
Review
Air Traffic Management as a Vital Part of Urban Air Mobility—A Review of DLR’s Research Work from 1995 to 2022
by Bianca I. Schuchardt, Dagi Geister, Thomas Lüken, Franz Knabe, Isabel C. Metz, Niklas Peinecke and Karolin Schweiger
Aerospace 2023, 10(1), 81; https://doi.org/10.3390/aerospace10010081 - 14 Jan 2023
Cited by 8 | Viewed by 4482
Abstract
Urban air mobility is a rapidly growing field of research. While drones or unmanned aerial vehicles have been operated mainly in the private and military sector in the past, an increasing range of opportunities is opening up for commercial applications. A new multitude [...] Read more.
Urban air mobility is a rapidly growing field of research. While drones or unmanned aerial vehicles have been operated mainly in the private and military sector in the past, an increasing range of opportunities is opening up for commercial applications. A new multitude of passenger-carrying drone or air taxi concepts promises to fulfill the dream of flying above congested urban areas. While early research has been focusing on vehicle development, solutions for urban air traffic management are lagging behind. This paper collects and reviews the main findings of past urban-air-mobility-related research projects at the German Aerospace Center (DLR) to serve as a basis for ongoing research from an air traffic management perspective. Full article
(This article belongs to the Special Issue Urban and Regional Air Mobility Research)
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15 pages, 3399 KiB  
Article
Remaining Useful Life Prediction for Aero-Engines Using a Time-Enhanced Multi-Head Self-Attention Model
by Xin Wang, Yi Li, Yaxi Xu, Xiaodong Liu, Tao Zheng and Bo Zheng
Aerospace 2023, 10(1), 80; https://doi.org/10.3390/aerospace10010080 - 13 Jan 2023
Cited by 8 | Viewed by 2758
Abstract
Data-driven Remaining Useful Life (RUL) prediction is one of the core technologies of Prognostics and Health Management (PHM). Committed to improving the accuracy of RUL prediction for aero-engines, this paper proposes a model that is entirely based on the attention mechanism. The attention [...] Read more.
Data-driven Remaining Useful Life (RUL) prediction is one of the core technologies of Prognostics and Health Management (PHM). Committed to improving the accuracy of RUL prediction for aero-engines, this paper proposes a model that is entirely based on the attention mechanism. The attention model is divided into the multi-head self-attention and timing feature enhancement attention models. The multi-head self-attention model employs scaled dot-product attention to extract dependencies between time series; the timing feature enhancement attention model is used to accelerate and enhance the feature selection process. This paper utilises Commercial Modular Aero-Propulsion System Simulation (C-MAPSS) turbofan engine simulation data obtained from NASA Ames’ Prognostics Center of Excellence and compares the proposed algorithm to other models. The experiments conducted validate the superiority of our model’s approach. Full article
(This article belongs to the Special Issue Machine Learning for Aeronautics)
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20 pages, 10276 KiB  
Article
High-Accuracy Finite Element Model Updating a Framed Structure Based on Response Surface Method and Partition Modification
by Qingyu Zhu, Qingkai Han, Jinguo Liu and Changshuai Yu
Aerospace 2023, 10(1), 79; https://doi.org/10.3390/aerospace10010079 - 13 Jan 2023
Cited by 3 | Viewed by 1680
Abstract
In this paper, a finite element model updating (FEMU) method is proposed based on the response surface model (RSM) and genetic algorithm (GA) to establish a high-precision finite element (FE) model of space station scientific experiment racks. First, the fine solid and mixed [...] Read more.
In this paper, a finite element model updating (FEMU) method is proposed based on the response surface model (RSM) and genetic algorithm (GA) to establish a high-precision finite element (FE) model of space station scientific experiment racks. First, the fine solid and mixed FE models are established, respectively, and a comparison of the modal test results is conducted. Then, an orthogonal experimental design is used to analyze the significance of the parameters, and the variables to be modified are determined. The design parameters are sampled via the Latin hyperbolic method and are substituted into the FE model to obtain the modal parameters of the scientific experiment rack. The mapping relationship between the design and modal parameters is fitted by constructing the Kriging function, and the RSM is established. The design parameters of the scientific experiment rack are optimized via GA, and the initial FE model is updated, which has the advantage of improving the computing efficiency. Finally, the updated FE model of the experiment rack is verified by frequency sweep and random vibration tests. The experimental results show that the proposed approach has high precision and computing efficiency, and compared with the test results, the modal frequency errors of the updated model are within 5%, and the vibration response errors under random excitation of the updated model are within 7%. Full article
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21 pages, 3080 KiB  
Article
A New Strategy of Satellite Autonomy with Machine Learning for Efficient Resource Utilization of a Standard Performance CubeSat
by Desalegn Abebaw Zeleke and Hae-Dong Kim
Aerospace 2023, 10(1), 78; https://doi.org/10.3390/aerospace10010078 - 13 Jan 2023
Cited by 2 | Viewed by 2273
Abstract
A mega constellation of Nano/microsatellites is the contemporary solution for global-level Earth observation demands. However, as most of the images taken by Earth-observing satellites are covered by clouds, storing and downlinking these images results in inefficient utilization of scarce onboard resources and bandwidth. [...] Read more.
A mega constellation of Nano/microsatellites is the contemporary solution for global-level Earth observation demands. However, as most of the images taken by Earth-observing satellites are covered by clouds, storing and downlinking these images results in inefficient utilization of scarce onboard resources and bandwidth. In addition, the trend of making satellite task execution plans by ground operators demands the efforts of experts or simulators to predict the real-time situation of satellites and to decide which tasks should be executed next. Granting controlled autonomy to satellites to perform onboard tasks will boost mission effectiveness. We experimented with granting controlled autonomy for satellites in performing onboard image classification and task scheduling. We designed a convolutional neural network-based binary image classification model with more than 99% accuracy in classifying clear and cloudy images. The model is configured to perform inference in low-performance computers of ordinary Cubesats. Moreover, we designed an autonomous satellite task scheduling mechanism based on reinforcement learning. It performs better than a custom heuristic-based method in scheduling onboard tasks. As a result, the proposed classification and scheduling techniques with machine learning ensured efficient utilization of onboard memory, power, and bandwidth in the highly resource-constrained CubeSat platforms and mission accomplishment of Nano/microsatellite constellations. Full article
(This article belongs to the Section Astronautics & Space Science)
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23 pages, 16915 KiB  
Article
Plasma Actuation for the Turbulent Mixing of Fuel Droplets and Oxidant Air in an Aerospace Combustor
by Zhengqi Tai, Qian Chen, Xiaofei Niu, Zhenhua Lin and Hesen Yang
Aerospace 2023, 10(1), 77; https://doi.org/10.3390/aerospace10010077 - 12 Jan 2023
Viewed by 1484
Abstract
In order to explore plasma-assisted turbulent mixing in aerospace engines, the dielectric barrier discharge plasma actuation for the turbulent mixing of fuel droplets and oxidant air in a ramjet combustor was studied using computational fluid dynamics. A two-way coupling of turbulent air and [...] Read more.
In order to explore plasma-assisted turbulent mixing in aerospace engines, the dielectric barrier discharge plasma actuation for the turbulent mixing of fuel droplets and oxidant air in a ramjet combustor was studied using computational fluid dynamics. A two-way coupling of turbulent air and discrete droplets was realized by Eulerian–Lagrangian simulation, and the dielectric barrier discharge plasma action on flow was modeled by body force. The results show that the plasma actuation can rearrange the recirculation zone behind the evaporative V-groove flameholder, and the main mechanism of actuation is to increase the local momentum of the fluid; the actuation dimension, actuation intensity, and actuation position of the dielectric barrier discharge plasma have strong effects on the turbulent mixing of fuel droplets and oxidant air; and a relatively optimal turbulent mixing can be achieved by adjusting the actuation parameters. Full article
(This article belongs to the Special Issue Thermal Fluid Dynamics and Control in Aerospace)
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25 pages, 19297 KiB  
Article
Numerical Simulations on the Performance of Two-Dimensional Serpentine Nozzle: Effect of Cone Mixer Angle and Aft-Deck
by Hamada Mohmed Abdelmotalib Ahmed, Byung-Guk Ahn and Jeekeun Lee
Aerospace 2023, 10(1), 76; https://doi.org/10.3390/aerospace10010076 - 11 Jan 2023
Cited by 2 | Viewed by 2075
Abstract
The current study addresses the effect of different designs of the exhaust mixer and aft-deck on the performance of a two-dimensional convergent nozzle represented by the internal and external flows and heat transfer process. The effect of different exhaust mixer cone angles of [...] Read more.
The current study addresses the effect of different designs of the exhaust mixer and aft-deck on the performance of a two-dimensional convergent nozzle represented by the internal and external flows and heat transfer process. The effect of different exhaust mixer cone angles of 10°, 15°, and 20°, and different aft-deck lengths of 140 mm, 280 mm, and 420 mm on the nozzle performance was investigated. To address the effect of an aft-deck, the flow behavior of a nozzle with an aft-deck was compared to that of a nozzle without an aft-deck. Then, the effect of different aft-deck lengths and different aft-decks with rectangular and trapezoid shapes was investigated. The results demonstrated that increasing the mixer cone angle resulted in decreasing the high-temperature core flow and increasing the low-temperature bypass flow. Increasing the mixer cone angle resulted in reducing the velocity inside the nozzle and at the exhausted jet, which can reduce the noise generated by the engine. Furthermore, increasing the mixer cone angle decreased the internal temperature of the nozzle and, along with the exhausted jet, decreased the infrared radiation. The results also illustrated that the presence of the aft-deck resulted in decreasing the pressure, temperature, and velocity inside the nozzle. The aft-deck also decreased the length and size of the potential core. The aft-deck length had no clear effect on the internal flow. However, increasing the aft-deck length resulted in a decrease in the exhaust gas temperature, which can decrease the infrared radiation. On another hand, using trapezoid and triangle aft-deck can enhance the performance of the nozzle by decreasing the velocity and temperature inside the nozzle and at the exhausted jet. Full article
(This article belongs to the Special Issue Thermal Fluid Dynamics and Control in Aerospace)
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29 pages, 2806 KiB  
Article
Numerical Simulation of an Electrothermal Ice Protection System in Anti-Icing and Deicing Mode
by Lokman Bennani, Pierre Trontin and Emmanuel Radenac
Aerospace 2023, 10(1), 75; https://doi.org/10.3390/aerospace10010075 - 11 Jan 2023
Cited by 4 | Viewed by 2646
Abstract
The design of efficient thermal ice protection systems is a challenging task as these systems operate in complex environments involving several coupled physical phenomena such as phase change, boundary-layer flow, and heat transfer. Moreover, certification rules are becoming more stringent, and there is [...] Read more.
The design of efficient thermal ice protection systems is a challenging task as these systems operate in complex environments involving several coupled physical phenomena such as phase change, boundary-layer flow, and heat transfer. Moreover, certification rules are becoming more stringent, and there is a strong incentive for the reduction of fuel consumption. In this context, numerical tools provide a powerful asset during the design phase but also to gain insight into the physical mechanisms at play. This article presents modeling and simulation strategies for thermal ice protection systems. First, the model describing the behavior of the thermal protection system is presented. Second, a model and associated numerical method is presented for unsteady ice accretion. Third, the coupling methodology between the ice accretion solver and the heat conduction solver is described. In the fourth part, different methods to simulate the boundary-layer flow are described. Finally, some relevant examples are presented, both in steady and unsteady configurations. Full article
(This article belongs to the Special Issue Deicing and Anti-Icing of Aircraft (Volume III))
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27 pages, 10900 KiB  
Article
Sensitivity Analysis of Wing Geometric and Kinematic Parameters for the Aerodynamic Performance of Hovering Flapping Wing
by Xinyu Lang, Bifeng Song, Wenqing Yang, Xiaojun Yang and Dong Xue
Aerospace 2023, 10(1), 74; https://doi.org/10.3390/aerospace10010074 - 10 Jan 2023
Cited by 2 | Viewed by 2181
Abstract
The wing planform and flapping kinematics are critical for the hovering flight of flapping wing micro air vehicles (FWMAVs). The degree of influence of wing geometry and kinematic parameters on aerodynamic performance still lacks in-depth analysis. In this study, a sensitivity analysis was [...] Read more.
The wing planform and flapping kinematics are critical for the hovering flight of flapping wing micro air vehicles (FWMAVs). The degree of influence of wing geometry and kinematic parameters on aerodynamic performance still lacks in-depth analysis. In this study, a sensitivity analysis was conducted based on the quasi-steady aerodynamic model. Each parameter was investigated independently by using the control variable method. The degree of each variable’s influence on lift, power, and power loading is evaluated and compared. Furthermore, detailed exponential relationships were established between the parameters and the corresponding aerodynamic properties. It is found that, for the geometric parameters, wing area has the greatest influence on lift, and the distribution of area has the most visible effect on aerodynamic power. All geometric parameters are negatively correlated with power loading. For the kinematic parameters, flapping frequency, compared with sweeping amplitude, results in faster lift growth and slower drop in power loading, while their influence on aerodynamic power is nearly comparable. A moderate pitching amplitude with advanced rotation will maximize the lift. For the flapping trajectory, lift and power loading are primarily affected by the shape of the pitching motion rather than the sweeping motion. But the sweeping motion seems to dominate the power consumption. The research in this paper is helpful to understand the effect of each parameter and provide theoretical guidance for the development of FWMAVs. Full article
(This article belongs to the Special Issue Flapping Wing MAV Mechanism, Control and Applications)
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11 pages, 4200 KiB  
Article
Microstructural Evolution and Mechanical Properties of Ti2AlNb/GH99 Superalloy Brazed Joints Using TiZrCuNi Amorphous Filler Alloy
by Junjie Cai, Shengpeng Hu, Hongbing Liu, Danyang Lin, Wei Fu and Xiaoguo Song
Aerospace 2023, 10(1), 73; https://doi.org/10.3390/aerospace10010073 - 10 Jan 2023
Cited by 1 | Viewed by 1758
Abstract
Dissimilar materials brazing of Ti2AlNb alloy to GH99 superalloy is of great pragmatic importance in the aerospace field, especially the lightweight space aircraft components manufacturing. In this work, TiZrCuNi amorphous filler alloy was used as brazing filler, and experiments were carried [...] Read more.
Dissimilar materials brazing of Ti2AlNb alloy to GH99 superalloy is of great pragmatic importance in the aerospace field, especially the lightweight space aircraft components manufacturing. In this work, TiZrCuNi amorphous filler alloy was used as brazing filler, and experiments were carried out at different brazing temperatures and times to investigate the changes in interfacial structures and properties of the joints. The typical interfacial microstructure was Ti2AlNb alloy/B2/β/Ti2Ni (Al, Nb) + B2/β + (Ti, Zr)2(Ni, Cu) + (Ti, Zr)(Ni, Cu)/(Cr, Ni, Ti) solid solution + (Ni, Cr) solid solution/GH99 superalloy when being brazed at 1000 °C for 8 min. The interfacial microstructure of the joints was influenced by diffusion and reaction between the filler alloy and the parent metal. The prolongation of brazing process parameters accelerated the diffusion and reaction of the liquid brazing alloy into both parent metals, which eventually led to the aggregation of (Ti, Zr)2(Ni, Cu) brittle phase and increased thickness of Ti2Ni (Al, Nb) layer. According to fracture analyses, cracks began in the Ti2Ni (Al, Nb) phase and spread with it as well as the (Ti, Zr)2(Ni, Cu) phase. The joints that were brazed at 1000 °C for 8 min had a maximum shear strength of ~216.2 MPa. Furthermore, increasing the brazing temperature or extending the holding time decreased the shear strength due to the coarse Ti2Ni (Al, Nb) phase and the continuous (Ti, Zr)2(Ni, Cu) phase. Full article
(This article belongs to the Section Aeronautics)
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20 pages, 5063 KiB  
Article
Numerical Study of Combustion and Emission Characteristics for Hydrogen Mixed Fuel in the Methane-Fueled Gas Turbine Combustor
by Kefu Wang, Feng Li, Tao Zhou and Yiqun Ao
Aerospace 2023, 10(1), 72; https://doi.org/10.3390/aerospace10010072 - 10 Jan 2023
Cited by 4 | Viewed by 2683
Abstract
The aeroderivative gas turbine is widely used as it demonstrates many advantages. Adding hydrogen to natural gas fuels can improve the performance of combustion. Following this, the effects of hydrogen enrichment on combustion characteristics were analyzed in an aeroderivative gas turbine combustor using [...] Read more.
The aeroderivative gas turbine is widely used as it demonstrates many advantages. Adding hydrogen to natural gas fuels can improve the performance of combustion. Following this, the effects of hydrogen enrichment on combustion characteristics were analyzed in an aeroderivative gas turbine combustor using CFD simulations. The numerical model was validated with experimental results. The conditions of the constant mass flow rate and the constant energy input were studied. The results indicate that adding hydrogen reduced the fuel residues significantly (fuel mass at the combustion chamber outlet was reduced up to 60.9%). In addition, the discharge of C2H2 and other pollutants was reduced. Increasing the volume fraction of hydrogen in the fuel also reduced CO emissions at the constant energy input while increasing CO emissions at the constant fuel mass flow rate. An excess in the volume fraction of added hydrogen changed the combustion mode in the combustion chamber, resulting in fuel-rich combustion (at constant mass flow rate) and diffusion combustion (at constant input power). Hydrogen addition increased the pattern factor and NOx emissions at the outlet of the combustion chamber. Full article
(This article belongs to the Section Aeronautics)
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17 pages, 417 KiB  
Article
Convex Optimization-Based Techniques for Trajectory Design and Control of Nonlinear Systems with Polytopic Range
by Olli Jansson and Matthew W. Harris
Aerospace 2023, 10(1), 71; https://doi.org/10.3390/aerospace10010071 - 10 Jan 2023
Viewed by 1855
Abstract
This paper presents new techniques for the trajectory design and control of nonlinear dynamical systems. The technique uses a convex polytope to bound the range of the nonlinear function and associates with each vertex an auxiliary linear system. Provided controls associated with the [...] Read more.
This paper presents new techniques for the trajectory design and control of nonlinear dynamical systems. The technique uses a convex polytope to bound the range of the nonlinear function and associates with each vertex an auxiliary linear system. Provided controls associated with the linear systems can be generated to satisfy an ordering constraint, the nonlinear control is computable by the interpolation of controls obtained by convex optimization. This theoretical result leads to two numerical approaches for solving the nonlinear constrained problem: one requires solving a single convex optimization problem and the other requires solving a sequence of convex optimization problems. The approaches are applied to two practical problems in aerospace engineering: a constrained relative orbital motion problem and an attitude control problem. The solve times for both problems and approaches are on the order of seconds. It is concluded that these techniques are rigorous and of practical use in solving nonlinear trajectory design and control problems. Full article
(This article belongs to the Special Issue Convex Optimization for Aerospace Guidance and Control Applications)
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18 pages, 1614 KiB  
Article
Autonomous Task Planning Method for Multi-Satellite System Based on a Hybrid Genetic Algorithm
by Jun Long, Shimin Wu, Xiaodong Han, Yunbo Wang and Limin Liu
Aerospace 2023, 10(1), 70; https://doi.org/10.3390/aerospace10010070 - 10 Jan 2023
Cited by 7 | Viewed by 2836
Abstract
The increasing number of satellites for specific space tasks makes it difficult for traditional satellite task planning that relies on ground station planning and on-board execution to fully exploit the overall effectiveness of satellites. Meanwhile, the complex and changeable environment in space also [...] Read more.
The increasing number of satellites for specific space tasks makes it difficult for traditional satellite task planning that relies on ground station planning and on-board execution to fully exploit the overall effectiveness of satellites. Meanwhile, the complex and changeable environment in space also poses challenges to the management of multi-satellite systems (MSS). To address the above issues, this paper formulates a mixed integer optimization problem to solve the autonomous task planning for MSS. First, we constructed a multi-agent-based on-board autonomous management and multi-satellite collaboration architecture. Based on this architecture, we propose a hybrid genetic algorithm with simulated annealing (H-GASA) to solve the multi-satellite cooperative autonomous task planning (MSCATP). With the H-GASA, a heuristic task scheduling scheme was developed to deal with possible task conflicts in MSCATP. Finally, a simulation scenario was established to validate our proposed H-GASA, which exhibits a superior performance in terms of computational power and success rate compared to existing algorithms. Full article
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18 pages, 6615 KiB  
Article
Design and Qualification of an Additively Manufactured Manifold for Aircraft Landing Gears Applications
by Maurizio Arena, Paolo Ambrogiani, Vincenzo Raiola, Francesco Bocchetto, Tommaso Tirelli and Martina Castaldo
Aerospace 2023, 10(1), 69; https://doi.org/10.3390/aerospace10010069 - 10 Jan 2023
Cited by 7 | Viewed by 3829
Abstract
The continuous pursuit of reducing weight and optimizing manufacturing processes is increasingly demanded in transportation vehicles, particularly in the aerospace field. In this context, additive manufacturing (AM) represents a well-known technique suitable for re-engineering traditional systems, minimizing the product’s weight/volume and print time. [...] Read more.
The continuous pursuit of reducing weight and optimizing manufacturing processes is increasingly demanded in transportation vehicles, particularly in the aerospace field. In this context, additive manufacturing (AM) represents a well-known technique suitable for re-engineering traditional systems, minimizing the product’s weight/volume and print time. The present research activity allowed for the exploration of the feasibility to replicate a conventional hydraulic manifold already certified for defence application with a lightweight and more compact issue through typical stringent aeronautical qualification steps. Computational modelling with lab test efforts made it possible to assess the compliance of the device with airworthiness certification requirements, giving a special focus to the fulfilment of structural requirements. In particular, the fatigue life characterization is still a crucial point to be well investigated in aeronautical components dfAM (designed for additive manufacturing) to demonstrate the maturity of the technology in the certification scenario. The new AM-driven design offers a more than 40 per cent weight reduction. Full article
(This article belongs to the Special Issue Metal Additive Manufacturing for Aerospace Applications)
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22 pages, 8429 KiB  
Article
Influence of Spinner Shape on Droplet Impact over Rotating Spinners
by Xuan Gao, Borong Qiu, Zongjie Wang and Haiwang Li
Aerospace 2023, 10(1), 68; https://doi.org/10.3390/aerospace10010068 - 9 Jan 2023
Cited by 3 | Viewed by 1875
Abstract
Droplet impact affects water collection, which is the key to investigating the icing process on an aero-engine spinner. Different from a stationary spinner, droplet impact is affected by Coriolis acceleration and centrifugal acceleration on rotating aero-engine spinners, showing different impact dynamics. Based on [...] Read more.
Droplet impact affects water collection, which is the key to investigating the icing process on an aero-engine spinner. Different from a stationary spinner, droplet impact is affected by Coriolis acceleration and centrifugal acceleration on rotating aero-engine spinners, showing different impact dynamics. Based on the Eulerian method, using the rotating coordinate system we numerically investigated droplet impact characteristics on three different shapes of aero-engine spinners using ANSYS Fluent. The results indicate that the impact area covered all the windward surface on the conical spinner, and only covered the windward surface prior to the impingement limit of the elliptical spinner and the coniptical spinner. The sensitivity of water collection to inflow velocity declined in the order of coniptical the spinner, the elliptical spinner, and the conical spinner. In addition, the elliptical region could effectively improve aerodynamic performance, as shown in a lower total pressure loss through the spinner. This work is relevant to the anti-icing system of a rotating aero-engine spinner. Full article
(This article belongs to the Special Issue Advances in Aerospace Sciences and Technology III)
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19 pages, 5621 KiB  
Article
Oil Particle-Induced Erosion Wear on the Deflector Jet Servo Valve Prestage
by Na Liang, Zhaohui Yuan and Fuli Zhang
Aerospace 2023, 10(1), 67; https://doi.org/10.3390/aerospace10010067 - 9 Jan 2023
Cited by 4 | Viewed by 1736
Abstract
Severe oil particle-induced erosion to the prestage component progressively degrades the overall performance of the deflector jet servo valve (DJSV), even leading to valve failure. Herein, we present an approach for evaluating degradation in performance and predicting the erosion lifespan of the DJSV [...] Read more.
Severe oil particle-induced erosion to the prestage component progressively degrades the overall performance of the deflector jet servo valve (DJSV), even leading to valve failure. Herein, we present an approach for evaluating degradation in performance and predicting the erosion lifespan of the DJSV on different levels of oil pollution. Specifically, a mathematical model of the whole valve was built based on a previously established working principle and physical mechanism. In addition, considering the horizontal and rotational particle motions, combined with impact of particle size distributions under different oil contamination degrees, an erosion model was constructed. Then, after simulating and analyzing the pressure characteristics before and after the erosion of prestage, the performance degradation of the whole valve was examined, thereby predicting the erosion life of the valve. Investigations revealed that the maximum erosion rate occurred at the shunt wedge of the receiving holes, which increased with the contamination degree and accelerated after level 7. After erosion, however, the control pressure difference decreased significantly, and erosion life followed exponential distribution corresponding to the distribution of particles under different pollution levels. The aforementioned investigation can thus help diagnose faults and optimize the design of the servo valves in service. Full article
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13 pages, 5404 KiB  
Article
Digital Twin Modeling Method for Hierarchical Stiffened Plate Based on Transfer Learning
by Ziyu Xu, Tianhe Gao, Zengcong Li, Qingjie Bi, Xiongwei Liu and Kuo Tian
Aerospace 2023, 10(1), 66; https://doi.org/10.3390/aerospace10010066 - 9 Jan 2023
Cited by 8 | Viewed by 1895
Abstract
As the key load-bearing component of spacecraft, the strength evaluation of stiffened plate structures faces two challenges. On the one hand, the simulation results are sometimes inaccurate, due to the simplification of the true loading conditions and modeling details. On the other hand, [...] Read more.
As the key load-bearing component of spacecraft, the strength evaluation of stiffened plate structures faces two challenges. On the one hand, the simulation results are sometimes inaccurate, due to the simplification of the true loading conditions and modeling details. On the other hand, data from the sensors cannot provide the full-field strength information of the structure, which may result in the misjudgment of the structural state. To this end, a digital twin modeling method of multi-source data fusion based on transfer learning is proposed in this paper. In transfer learning, simulation data and sensor data are utilized as the source dataset and the target dataset, respectively. First, a pre-trained deep neural network (DNN) model is established based on the source dataset. Then, the pre-trained DNN model is fine-tuned based on the target dataset using a lower learning rate and fewer training epochs. Finally, a digital twin model can be built, which is capable of visualizing the full-field strength information of the stiffened plate structure. To verify the effectiveness of the proposed method, an experimental study on a hierarchical stiffened plate is carried out. Compared with the traditional data fusion method, the results verify the high prediction accuracy and efficiency of the proposed method, demonstrating its potential for the strength health monitoring of spacecraft in orbit. Full article
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28 pages, 9015 KiB  
Article
The Influence of Thrust Chamber Structure Parameters on Regenerative Cooling Effect with Hydrogen Peroxide as Coolant in Liquid Rocket Engines
by Chuang Zhou, Nanjia Yu, Shuwen Wang, Shutao Han, Haojie Gong, Guobiao Cai and Jue Wang
Aerospace 2023, 10(1), 65; https://doi.org/10.3390/aerospace10010065 - 9 Jan 2023
Cited by 2 | Viewed by 5062
Abstract
Liquid rocket engines with hydrogen peroxide and kerosene have the advantages of high density specific impulse, high reliability, and no ignition system. At present, the cooling problem of hydrogen peroxide engines, especially with regenerative cooling, has been little explored. In this study, a [...] Read more.
Liquid rocket engines with hydrogen peroxide and kerosene have the advantages of high density specific impulse, high reliability, and no ignition system. At present, the cooling problem of hydrogen peroxide engines, especially with regenerative cooling, has been little explored. In this study, a realizable k-epsilon turbulence model, discrete phase model, eddy dissipation concept model, and 10-step 10-component reaction mechanism of kerosene with oxygen are used. The increased rib height of the regenerative cooling channel causes the inner wall temperature of the engine increases, the average temperature of the coolant outlet decreases slightly, and the coolant pressure decreases. The overall wall temperature decreases as the rib width of the regenerative cooling channel increases. However, in the nozzle throat area, the wall temperature increases, the average coolant outlet temperature decreases, and the coolant pressure drop increases. A decrease in the inner wall thickness of the regenerative cooling channel results in a significant decrease in the wall temperature and a small increase in the average coolant outlet temperature. These findings contribute to the further development of the engine with hydrogen peroxide and can guide the design of its regenerative cooling process. Full article
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20 pages, 6990 KiB  
Article
Computational Fluid Dynamics Analyses of a Wing with Distributed Electric Propulsion
by Oreste Russo, Andrea Aprovitola, Donato de Rosa, Giuseppe Pezzella and Antonio Viviani
Aerospace 2023, 10(1), 64; https://doi.org/10.3390/aerospace10010064 - 8 Jan 2023
Viewed by 2563
Abstract
The efficiency increase that distributed propulsion could deliver for future hybrid-electric aircraft is in line with the urgent demand for higher aerodynamic performances and a lower environmental impact. Several consolidated proprietary tools (not always available) are developed worldwide for distributed propulsion simulation. Therefore, [...] Read more.
The efficiency increase that distributed propulsion could deliver for future hybrid-electric aircraft is in line with the urgent demand for higher aerodynamic performances and a lower environmental impact. Several consolidated proprietary tools (not always available) are developed worldwide for distributed propulsion simulation. Therefore, prediction and comparisons of propeller performances, with computational fluid dynamic codes featuring different implementation of solvers, numerical schemes, and turbulence models, is of interest to a wider audience of research end-users. In this framework, the paper presents a cross-comparison study among different CFD solvers, the SU2 Multiphysics Simulation and Design Software, the CIRA proprietary flow solver UZEN, and the commercial ANSYS-FLUENT code, for the simulation of a wing section with a tractor propeller at different flow attitudes. The propeller is modelled as an actuator disk according to the general momentum theory and is accounted for in the flow solvers as a boundary condition, for the momentum and energy equations. In this study, a propeller with a fixed advance ratio J=0.63 is considered, while propeller performances are assumed variable along with the radius. To perform the comparisons among the solvers, an in-house procedure, which provides the input thrust and torque distributions in a unified format among the three solvers, is developed. Steady RANS simulations are performed at Re=1.7×106 and M=0.11, for the flowfield of an isolated propeller. Successively, a wing section with a fixed forward-mounted propeller configuration with no nacelle, is studied at α=0,4, and 8 angles of attack. The comparisons in terms of the lift coefficient show a good agreement among the three flow solvers both in power-off and power-on conditions. Simulations also evidenced the strong stability preserving property of upwind schemes, applied to propeller simulation at low-Mach number. Some discrepancies in the drag coefficient are observed and related to different levels of numerical diffusion between the three codes, which affects the downstream wake. Differences in flow properties in near disk region are observed and explained considering the different hub implementations. Full article
(This article belongs to the Special Issue Fluid Flow Mechanics (2nd Edition))
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16 pages, 4375 KiB  
Article
Filter Design for Laser Inertial Navigation System Based on Improved Pigeon-Inspired Optimization
by Zhihua Li, Lin Zhang and Kunlun Wu
Aerospace 2023, 10(1), 63; https://doi.org/10.3390/aerospace10010063 - 7 Jan 2023
Cited by 2 | Viewed by 1487
Abstract
The laser gyroscope of Laser Inertial Navigation System (LINS) eliminates the influence of the locked zone with mechanical dither. The output information of laser gyroscopes must be filtered before use to eliminate vibration noise. Laser gyroscope filters are designed according to the instrument [...] Read more.
The laser gyroscope of Laser Inertial Navigation System (LINS) eliminates the influence of the locked zone with mechanical dither. The output information of laser gyroscopes must be filtered before use to eliminate vibration noise. Laser gyroscope filters are designed according to the instrument accuracy, calculation capacity, vibration frequency, system dynamic characteristics, and other indicators. In this paper, a pigeon-inspired optimization (PIO) method is proposed for use in filter design. The PIO method can flexibly design filters with excellent performance according to the indicator requirements. In the method, the constraints and indicators of the amplitude, phase and order of the LINS filter are firstly confirmed according to the application requirements; then, the objective function is established, and the parameters to be optimized of the PIO are set according to the order of the filter; finally, the PIO method is used to obtain filter parameters that can satisfy the constraints and achieve better performance. Referring to the idea of biological evolution mechanisms, we propose a new improved pigeon-inspired optimization method based on natural selection and Gaussian mutation (SMPIO), which can obtain more stable results and higher accuracy. In the SMPIO method, the particle swarm is firstly selected by natural selection, that is, the particles are sorted according to the fitness function, and some particles with poor fitness are replaced by those with better fitness; then, all particles are subjected to Gaussian mutation to obtain a better global optimum. SMPIO method can flexibly design filters according to the comprehensive requirements of laser gyro performance and navigation control indicators, which cannot be achieved by traditional filter design methods; the improvement based on natural selection and Gaussian mutation enables SMPIO to have faster convergence speed, and higher accuracy. Full article
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18 pages, 2989 KiB  
Article
A Data-Driven Method for Arrival Sequencing and Scheduling Problem
by Zhuoming Du, Junfeng Zhang and Bo Kang
Aerospace 2023, 10(1), 62; https://doi.org/10.3390/aerospace10010062 - 7 Jan 2023
Viewed by 1876
Abstract
Decision support tools for arrival sequencing and scheduling could assist air traffic controllers in managing the arrival aircraft in terminal areas. However, one critical issue is that the current method for dealing with the arrival sequencing and scheduling problem does not consider the [...] Read more.
Decision support tools for arrival sequencing and scheduling could assist air traffic controllers in managing the arrival aircraft in terminal areas. However, one critical issue is that the current method for dealing with the arrival sequencing and scheduling problem does not consider the dynamic traffic situation and the human working experience, which results in a deviation between the scheduled and actual landing sequences. This paper develops a data-driven method to address this issue. Firstly, the random forest model is applied to predict the estimated time of arrival (ETA). During the ETA prediction, the trajectory, operation, and airport-related factors that could increase the prediction accuracy are considered. Secondly, the landing sequence is obtained by sorting the predicted ETAs. Thirdly, two optimization methods are proposed to generate the scheduled time of arrival (STA). The former uses the predicted ETAs as inputs and then directly optimizes the landing sequence and the STA. The latter uses both the predicted ETA and the landing sequence as inputs for further optimization. Finally, these proposed methods are evaluated with three sets of historical data on arrival operations at Changsha Huanghua International Airport (ZGHA). The results show that the RF-based ETA prediction method could improve scheduling performance. Moreover, the proposed optimization methods could provide controllers with a more appropriate decision advisory. Such advisories could simultaneously reduce the operation efficiency indicators (average/maximum delay or dwell time) and the operation complexity indicators (Kendall rank correlation or position shift). Full article
(This article belongs to the Section Air Traffic and Transportation)
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17 pages, 5346 KiB  
Article
Adapting Commercial Best Practices to U.S. Air Force Maintenance Scheduling
by Kyle Blond, Austin Himschoot, Eric Klein, Steven Conley and Anne Clark
Aerospace 2023, 10(1), 61; https://doi.org/10.3390/aerospace10010061 - 7 Jan 2023
Cited by 3 | Viewed by 2676
Abstract
This paper presents how the Inspection Development Framework’s (IDF) novel maintenance scheduling technique increased aircraft utilization and availability in a sample of the United States Air Force’s (USAF) C-5M Super Galaxy fleet. The hypothesis tested was “Can we execute segmented maintenance requirements during [...] Read more.
This paper presents how the Inspection Development Framework’s (IDF) novel maintenance scheduling technique increased aircraft utilization and availability in a sample of the United States Air Force’s (USAF) C-5M Super Galaxy fleet. The hypothesis tested was “Can we execute segmented maintenance requirements during ground time opportunities in order to optimize flying?” We applied IDF to decompose the C-5M’s five-day Home Station Check (HSC) inspection into smaller work packages that subordinate to operational requirements and maintenance resource availability. Ten HSCs at Dover and Travis Air Force Base (AFB) were modified using IDF and measured against a control group of traditional HSCs. While statistical significance was not achieved given the small sample size, anecdotal results demonstrate improvements in maintenance downtime, sortie count, and flight hours for the experimental group across the two bases. Specifically, the pathfinder’s observed results extrapolated to all HSCs at each base projected an additional 15 flying days per year at Dover AFB and 29 sorties per year at Travis AFB. These C-5M improvements serve as a proof-of-concept for the USAF adapting commercial best practices to address declining aircraft readiness. IDF’s more agile and dynamic scheduling techniques also enable easier adoption of Condition Based Maintenance through a more integrated approach to optimally schedule maintenance requirements. Full article
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