A  B  C  D  E  F  G  H  I  J  K  L  M  N  O  P  Q  R  S  T  U  V  W  X  Y  Z  

              [Sort by number of followers]   [Restore default list]

  Subjects -> AERONAUTICS AND SPACE FLIGHT (Total: 124 journals)
Showing 1 - 30 of 30 Journals sorted alphabetically
Acta Astronautica     Hybrid Journal   (Followers: 220)
Advances in Aerospace Engineering     Open Access   (Followers: 74)
Advances in Aerospace Science and Technology     Open Access   (Followers: 14)
Advances in Astronautics Science and Technology     Hybrid Journal   (Followers: 2)
Advances in Space Research     Hybrid Journal   (Followers: 295)
Aeronautical Journal, The     Hybrid Journal   (Followers: 9)
Aerospace     Open Access   (Followers: 64)
Aerospace Medicine and Human Performance     Full-text available via subscription   (Followers: 22)
Aerospace Science and Technology     Hybrid Journal   (Followers: 306)
Aerospace Systems     Hybrid Journal   (Followers: 10)
Aerospace technic and technology     Open Access   (Followers: 7)
Aerotecnica Missili & Spazio : Journal of Aerospace Science, Technologies & Systems     Hybrid Journal   (Followers: 6)
AIAA Journal     Hybrid Journal   (Followers: 1002)
Air Medical Journal     Hybrid Journal   (Followers: 6)
Aircraft Engineering and Aerospace Technology     Hybrid Journal   (Followers: 139)
Artificial Satellites     Open Access   (Followers: 21)
ASTRA Proceedings     Open Access   (Followers: 3)
Astrodynamics     Hybrid Journal   (Followers: 4)
Aviation     Open Access   (Followers: 12)
Aviation in Focus - Journal of Aeronautical Sciences     Open Access   (Followers: 7)
Aviation Psychology and Applied Human Factors     Hybrid Journal   (Followers: 23)
Aviation Week     Full-text available via subscription   (Followers: 411)
Canadian Aeronautics and Space Journal     Full-text available via subscription   (Followers: 31)
CEAS Aeronautical Journal     Hybrid Journal   (Followers: 30)
Chinese Journal of Aeronautics     Open Access   (Followers: 19)
Ciencia y Poder Aéreo     Open Access   (Followers: 3)
Civil Aviation High Technologies     Open Access   (Followers: 6)
Control Systems     Hybrid Journal   (Followers: 235)
Cosmic Research     Hybrid Journal   (Followers: 5)
Egyptian Journal of Remote Sensing and Space Science     Open Access   (Followers: 25)
Fatigue of Aircraft Structures     Open Access   (Followers: 21)
Frontiers in Aerospace Engineering     Open Access   (Followers: 20)
Frontiers in Astronomy and Space Sciences     Open Access   (Followers: 15)
Gyroscopy and Navigation     Hybrid Journal   (Followers: 177)
IEEE Aerospace and Electronic Systems Magazine     Full-text available via subscription   (Followers: 251)
IEEE Journal on Miniaturization for Air and Space Systems     Hybrid Journal   (Followers: 2)
IEEE Transactions on Aerospace and Electronic Systems     Hybrid Journal   (Followers: 281)
IEEE Transactions on Circuits and Systems I: Regular Papers     Hybrid Journal   (Followers: 43)
International Journal of Aeroacoustics     Hybrid Journal   (Followers: 37)
International Journal of Aerodynamics     Hybrid Journal   (Followers: 46)
International Journal of Aeronautical and Space Sciences     Hybrid Journal   (Followers: 4)
International Journal of Aerospace Engineering     Open Access   (Followers: 86)
International Journal of Aerospace Innovations     Full-text available via subscription   (Followers: 23)
International Journal of Aerospace Psychology     Hybrid Journal   (Followers: 22)
International Journal of Aerospace Sciences     Open Access   (Followers: 36)
International Journal of Applied Geospatial Research     Hybrid Journal   (Followers: 7)
International Journal of Aviation Management     Hybrid Journal   (Followers: 5)
International Journal of Aviation Technology, Engineering and Management     Full-text available via subscription   (Followers: 8)
International Journal of Aviation, Aeronautics, and Aerospace     Open Access   (Followers: 9)
International Journal of Crashworthiness     Hybrid Journal   (Followers: 10)
International Journal of Micro Air Vehicles     Open Access   (Followers: 11)
International Journal of Satellite Communications Policy and Management     Hybrid Journal   (Followers: 15)
International Journal of Space Science and Engineering     Hybrid Journal   (Followers: 13)
International Journal of Space Structures     Full-text available via subscription   (Followers: 19)
International Journal of Space Technology Management and Innovation     Full-text available via subscription   (Followers: 11)
International Journal of Sustainable Aviation     Hybrid Journal   (Followers: 5)
Investigación Pecuaria     Open Access   (Followers: 1)
Journal of Aerodynamics     Open Access   (Followers: 27)
Journal of Aeronautical Materials     Open Access   (Followers: 10)
Journal of Aerospace Engineering     Full-text available via subscription   (Followers: 66)
Journal of Aerospace Engineering & Technology     Full-text available via subscription   (Followers: 22)
Journal of Aerospace Information Systems     Hybrid Journal   (Followers: 27)
Journal of Aerospace Information Systems     Hybrid Journal   (Followers: 57)
Journal of Aerospace Technology and Management     Open Access   (Followers: 10)
Journal of Aircraft     Hybrid Journal   (Followers: 263)
Journal of Aircraft and Spacecraft Technology     Open Access   (Followers: 15)
Journal of Airline and Airport Management     Open Access   (Followers: 11)
Journal of Astrobiology & Outreach     Open Access   (Followers: 5)
Journal of Aviation Technology and Engineering     Open Access   (Followers: 10)
Journal of Aviation/Aerospace Education & Research     Open Access   (Followers: 2)
Journal of Engineering and Technological Sciences     Open Access   (Followers: 2)
Journal of Guidance, Control, and Dynamics     Hybrid Journal   (Followers: 165)
Journal of KONBiN     Open Access   (Followers: 4)
Journal of Navigation     Hybrid Journal   (Followers: 176)
Journal of Propulsion and Power     Hybrid Journal   (Followers: 569)
Journal of Space Safety Engineering     Hybrid Journal   (Followers: 8)
Journal of Space Weather and Space Climate     Open Access   (Followers: 30)
Journal of Spacecraft and Rockets     Hybrid Journal   (Followers: 702)
Journal of Spatial Science     Hybrid Journal   (Followers: 4)
Journal of the American Helicopter Society     Full-text available via subscription   (Followers: 9)
Journal of the Astronautical Sciences     Hybrid Journal   (Followers: 11)
Journal of the Australasian Society of Aerospace Medicine     Open Access   (Followers: 3)
Journal of Wind Engineering and Industrial Aerodynamics     Hybrid Journal   (Followers: 21)
Life Sciences in Space Research     Hybrid Journal   (Followers: 5)
MAD - Magazine of Aviation Development     Open Access   (Followers: 3)
Mekanika : Jurnal Teknik Mesin i     Open Access  
Microgravity Science and Technology     Hybrid Journal   (Followers: 3)
New Space     Hybrid Journal   (Followers: 6)
Nonlinear Dynamics     Hybrid Journal   (Followers: 19)
npj Microgravity     Open Access   (Followers: 3)
Open Aerospace Engineering Journal     Open Access   (Followers: 4)
Perspectives of Earth and Space Scientists i     Open Access   (Followers: 1)
Population Space and Place     Hybrid Journal   (Followers: 10)
Problemy Mechatroniki. Uzbrojenie, lotnictwo, inżynieria bezpieczeństwa / Problems of Mechatronics. Armament, Aviation, Safety Engineering     Open Access   (Followers: 3)
Proceedings of the Human Factors and Ergonomics Society Annual Meeting     Hybrid Journal   (Followers: 16)
Proceedings of the Institution of Mechanical Engineers Part G: Journal of Aerospace Engineering     Hybrid Journal   (Followers: 42)
Progress in Aerospace Sciences     Full-text available via subscription   (Followers: 82)
Propulsion and Power Research     Open Access   (Followers: 89)
REACH - Reviews in Human Space Exploration     Full-text available via subscription   (Followers: 5)
Research & Reviews : Journal of Space Science & Technology     Full-text available via subscription   (Followers: 20)
RocketSTEM     Free   (Followers: 5)
Russian Aeronautics (Iz VUZ)     Hybrid Journal   (Followers: 23)
Science and Education : Scientific Publication of BMSTU     Open Access   (Followers: 1)
Space and Polity     Hybrid Journal   (Followers: 6)
Space Policy     Hybrid Journal   (Followers: 30)
Space Research Today     Full-text available via subscription   (Followers: 43)
Space Safety Magazine     Free   (Followers: 50)
Space Science International     Open Access   (Followers: 117)
Space Science Reviews     Hybrid Journal   (Followers: 92)
SpaceNews     Free   (Followers: 779)
Spatial Information Research     Hybrid Journal   (Followers: 1)
Transactions on Aerospace Research     Open Access   (Followers: 1)
Transport and Aerospace Engineering     Open Access   (Followers: 4)
Transportmetrica A : Transport Science     Hybrid Journal   (Followers: 7)
Unmanned Systems     Hybrid Journal   (Followers: 4)
Xibei Gongye Daxue Xuebao / Journal of Northwestern Polytechnical University     Open Access  
Вісник Національного Авіаційного Університету     Open Access   (Followers: 1)

              [Sort by number of followers]   [Restore default list]

Similar Journals
Journal Cover
International Journal of Aerospace Engineering
Journal Prestige (SJR): 0.232
Citation Impact (citeScore): 1
Number of Followers: 86  

  This is an Open Access Journal Open Access journal
ISSN (Print) 1687-5966 - ISSN (Online) 1687-5974
Published by Hindawi Homepage  [339 journals]
  • Study of the Mechanical Properties of a CMDB Propellant Over a Wide Range
           of Strain Rates Using a Group Interaction Model

    • Abstract: Composite modified double base (CMDB) propellants are heterogeneous propellants in which properties are significantly improved by adding solid particles into the polymer matrix. A molecular group interaction model that can predict the mechanical properties of polymers through a molecular structure is used to predict the viscoelastic behavior of the CMDB propellant. Considering that the addition of solid particles will improve the crosslinking degree between polymer molecules and reduce its secondary loss peak, the input parameters of the model are modified through dynamic mechanical analysis (DMA) experimental data. By introducing the strain rate into the expression of model glass transition temperature, the mechanical properties of propellant over a wide strain range ( s-1 ~ 3000 s-1) are obtained. The reliability of the model is verified by comparison with uniaxial compression test data. By modifying the input parameters of the model, the effects of different mass ratios of nitrocellulose (NC)/nitroglycerin (NG) on the mechanical properties of the CMDB propellant were analyzed. The results show that the glass transition loss increases with increasing mass ratio of NC/NG, while Young’s modulus and yield stress decrease.
      PubDate: Sat, 14 May 2022 09:20:01 +000
       
  • Enhancing Short-Term Prediction of BDS-3 Satellite Clock Bias Based with
           BSO Optimized BP Neural Network

    • Abstract: The satellite clock bias (SCB) prediction plays an important role in high-accuracy and real-time navigation and positioning. When predicting the SCB, the performance of the BP neural network is affected by the local optimum due to inaccurate initial parameters. Therefore, we propose an improved BP neural network based on the beetle swarm optimization (BSO-BP) algorithm to improve the performance of SCB prediction in third-generation Beidou satellite navigation system (BDS-3). The proposed model takes advantage of group learning strategy to optimize the initialization parameters of the BP neural network and obtains globally optimized parameters. In order to verify the proposed BSO-BP model, 15 BDS satellites are analyzed in terms of prediction accuracy and stability of SCB. The experimental results show that when predicting 1 hour SCB based on a 12 hours SCB data, the prediction accuracy of the BSO-BP model is the best, with an average accuracy of 0.064 ns. As compared with the LP, QP, and GM models, the average prediction accuracy of the proposed BSO-BP model increases by about 72.6%, 43.4%, and 86%, respectively. As the prediction time increases, the influence of the inaccurate initial parameters on SCB prediction gradually decreases, and the prediction accuracy improves. The proposed BSO-BP model has the best accuracy and stability when predicting the 1 h SCB based on the same data. The prediction stability of the proposed BSO-BP model improves by more than 36% as compared with LP, QP, and GM models. In addition, the prediction accuracies of PHM clock and Rb-II clock improved by more than 47%, as compared with that of the Rb clock. Therefore, the overall performance of the atomic clock based on BDS-3 is better than BDS-2. The positioning accuracy of the BSO-BP model can reach the centimeter level in east, north, and up directions.
      PubDate: Wed, 11 May 2022 10:50:03 +000
       
  • Pretension Design and Analysis of Deployable Mesh Antenna considering the
           Effect of Gravity

    • Abstract: The difference between the space and the earth environment has significantly influenced the shape accuracy of the antenna reflector surface. With the increasing demand for the aperture of the antenna reflector, gravity has become one of the main factors that restrict the accuracy. In this paper, a new method for pretension design considering the effect of gravity is proposed. The design surface can be well restored to the ideal surface in orbit. Meanwhile, this method can avoid flipping antenna reflectors or extensive experiments for modification during ground adjustment. Then, the feasibility and effectiveness of the design method are validated by several numerical simulations. Moreover, the results are compared with the previous method and the differences have been discussed in detail. Finally, the effects of cable radius, cable length, and elastic modulus of the mesh reflector have been researched, respectively.
      PubDate: Mon, 09 May 2022 17:20:03 +000
       
  • Finite-Time Orbit Control for Spacecraft Formation with External
           Disturbances and Limited Data Communication

    • Abstract: This work addresses the finite-time orbit control problem for spacecraft formation flying with external disturbances and limited data communication. A hysteretic quantizer is employed for data quantization in the controller-actuator channel to decrease the communication rate and prevent the chattering phenomenon caused by the logarithmic quantizer. Combined with the adding one power integrator method and backstepping technique, a new finite-time tracking control strategy with adaptation law is designed to ensure that the closed-loop system is practical finite-time stable, and that the tracking errors of relative position and velocity are bounded within finite-time despite with limited data communication and external disturbances. Finally, an example is shown to validate the effectiveness of the proposed finite-time tracking controller.
      PubDate: Mon, 09 May 2022 11:20:03 +000
       
  • A UAV Pursuit-Evasion Strategy Based on DDPG and Imitation Learning

    • Abstract: The UAV pursuit-evasion strategy based on Deep Deterministic Policy Gradient (DDPG) algorithm is a current research hotspot. However, this algorithm has the defect of low efficiency in sample exploration. To solve this problem, this paper uses the imitation learning (IL) to improve the DDPG exploration strategy. A kind of quasiproportional guidance control law is designed to generate effective learning samples, which are used as the data of the initial experience pool of DDPG algorithm. The UAV pursuit-evasion strategy based on DDPG and imitation learning (IL-DDPG) is proposed, and the algorithm obtains the data from the experience pool for experience playback learning, which improves the exploration efficiency of the algorithm in the initial stage of training and avoids the problem of too many useless exploration in the training process. The simulation results show that the trained pursuit-UAV can flexibly adjust the flight speed and flight attitude to pursuit the evasion-UAV quickly. It also verifies that the improved DDPG algorithm is more effective than the basic DDPG algorithm to improve the training efficiency.
      PubDate: Mon, 09 May 2022 11:20:03 +000
       
  • Application of Gap Metric to LADRC Design in Multilinear Model of SDR

    • Abstract: The solid ducted rocket ramjet (SDR) system faces many disturbances in the process of operation, and the linear active disturbance rejection controller (LADRC) has been widely used in engineering to solve such problems. However, the SDR also has strong nonlinearity, which brings a great challenge to the application of the LADRC in the gas flow regulation of the SDR. And the problem of fast adjustment of the “compensation factor” is one of the main difficulties in LADRC. In this paper, under the LADRC frame, the gas generator system’s closed-loop stability of the SDR was analyzed and the range of compensation factors had been calculated, and then, the “gap factor” was introduced and the “cross-iteration” method was used to quickly map out the “compensation factor” in the multilinear model controller based on the variation of the zero-point position of the system and the gap metric between adjacent set points. This greatly simplifies the parameter tuning process of the LADRC when it was applied to strongly nonlinear systems. Finally, through the comparison of simulation with adaptive PI controller and model-assisted LADRC (M-LADRC), the results have shown that the control method designed in this paper can obtain satisfactory performance and has a good engineering application prospect.
      PubDate: Fri, 06 May 2022 11:05:04 +000
       
  • Fast and Accurate Hand Visual Detection by Using a Spatial-Channel
           Attention SSD for Hand-Based Space Robot Teleoperation

    • Abstract: Space robot teleoperation is an important technology in the space human-robot interaction and collaboration. Hand-based visual teleoperation can make the operation more natural and convenient. The fast and accuracy hand detection is one of the most difficult and important problem in the hand-based space robot teleoperation. In this work, we propose a fast and accurate hand detection method by using a spatial-channel attention single shot multibox detector (SCA-SSD). The SSD framework is used and improved in our method by introducing spatial-channel attentions with feature fusion. To increase the restricted receptive field in shallow layers, two shallow layers are fused with deep layers by using feature fusion modules. And spatial attention and channel-wise attention are also used to extract more efficient features. This method can not only ease the computational burden but also bring more contextual information. To evaluate the effectiveness of the proposed method, experiments on some public datasets and a custom astronaut hand detection dataset (AHD) are conducted. The results show that our method can improve the hand detection accuracy by 2.7% compared with the original SSD with only 15 fps speed drops. In addition, the space robot teleoperation experiment proves that our hand detection method can be well utilized in the space robot teleoperation system.
      PubDate: Wed, 04 May 2022 09:35:02 +000
       
  • Predictive Differential Game Guidance Approach for Hypersonic Target
           Interception Based on CQPSO

    • Abstract: In the descent phase of the hypersonic target flight trajectory, the hypersonic speed of the target makes the reaction time shorter. Due to overload restrictions, it is challenging for the interceptor to achieve successful interception. To address this problem, a predictive differential game guidance approach based on dynamic optimization algorithm is proposed to relax the interceptor acceleration requirements. Two-dimensional kinematics and dynamics engagement mode for hypersonic target interception is formulated as a nonlinear differential control model in the presence of matched uncertainties. The nonlinear differential model is transformed into a differential game model by combining a performance index. The performance index is positively correlated with the Line-Of-Sight (LOS) rate and control effort of interceptor and negatively correlated with the target maneuver. The Chaotic Quantum Particle Swarm Optimization (CQPSO) algorithm is utilized to address the nonlinear differential game problem to generate the instantaneous and predicted guidance commands for the interceptor and target. Numerical examples are given to verify the performance of the proposed guidance law in various engagement scenarios, including different target maneuvers, initial heading angles and target overload. Moreover, the performance of the algorithm is validated comparing with traditional and state-of-the-art guidance laws.
      PubDate: Mon, 02 May 2022 12:50:01 +000
       
  • Satellite In-Orbit Secondary Collision Risk Assessment

    • Abstract: The massive mega constellation of satellites will have a significant impact on global space safety. With Starlink as an example, this paper is aimed at assessing the risk of in-orbit collision, analyzing the probability of collision in orbit in its natural operating state, and forecasting the probability of secondary collision between the collision-generated short-term debris cloud and satellites in the same orbit. The mass, size, velocity, and direction of space debris in a particular orbit of Starlink satellite are calculated based on the MASTER-8 model, and the shape characteristics of the Starlink satellite are added to the model to determine the probability of a Starlink satellite colliding with space debris in that orbit. A modified spacecraft impact disintegration model then is used to calculate the collision results and estimate the collision threat level of the short-term debris cloud formed by the Starlink satellite after its destruction to satellites in the same orbit. The results indicate that the collision probability of Starlink satellite in orbit natural operation exceeds the red warning threshold 10-4 that the satellite disintegration after the first collision will generate 14088 pieces of debris over 1 cm, of which 4092 debris are potentially dangerous to other spacecraft, and that the collision probability to a satellite in the same orbit exceeds the red warning threshold of 10-4 within 30 minutes, implying that collision avoidance needs to be improved.
      PubDate: Mon, 02 May 2022 12:50:00 +000
       
  • Multiple Spacecraft Formation Flying Control around Artificial Equilibrium
           Point Using Propellantless Approach

    • Abstract: This paper demonstrates a detailed analysis of the feasibility for compact formation system around an L2-type artificial equilibrium point by means of continuous low-thrust propulsion in the hybrid form of solar sail and Coulomb force propulsion. Firstly, in view of non-ideal solar sail, the position of L2-type artificial equilibrium point and numerical periodic orbits around L2 utilized as leader’s nominal trajectory are given. Secondly, considering the external disturbances in the deep space environment, the nonlinear dynamic model of the spacecraft formation system based on the circular restricted three-body problem (CRTBP) is derived, under the assumption that the leader covers the nominal trajectory and each follower adjusts its propulsive acceleration vector (that is, both its sail attitude and electrostatic charge) in order to track a desired relative trajectory. Thirdly, based on a new double power combination function reaching law, a fast integral terminal sliding mode control methodology (MFITSM) is ameliorated to achieve orbital tracking rapidly, which has better robustness against external disturbances and the buffeting effect during spacecraft propulsion simultaneously. To properly allocate control inputs, a novel optimal allocation scheme is designed to calculate the charge product of the spacecrafts and sail attitude angles, which can make the magnitude of the acceleration required from the Coulomb propulsion system minimum and avoid formation geometry instabilities by balancing electrostatic interaction between adjacent spacecraft. Finally, several numerical examples are conducted to validate the superiority of the proposed control algorithm.
      PubDate: Mon, 02 May 2022 07:20:01 +000
       
  • A Cycle Slip Detection and Repair Method Using BDS Triple-Frequency
           Optimization Combination with Wavelet Denoising

    • Abstract: The traditional triple-frequency geometry-free pseudorange minus phase (GFPMP) method is very susceptible to the influence of pseudorange observation noise, and it is difficult to detect insensitive small cycle slips. The dual-frequency phase ionospheric residual (PIR) method has the ability to detect sensitive small cycle slips, but its detection results have multivalue problems. In view of this, a GFPMP-PIR combination model method with wavelet denoising (GPW) is proposed here. The idea of this method is as follows: firstly, wavelet transform is used to denoise the pseudorange observations; then, by optimizing and selecting the combination coefficients with the minimum condition, an optimized GFPMP-PIR combination model is constructed. Hence, the source data quality is assured through wavelet denoising. And the accuracy of cycle slip detection and repair is improved by using the dual-frequency PIR combination. Moreover, the multivalue problem of the dual-frequency PIR method is solved by triple-frequency GFPMP combination; finally, the BeiDou navigation satellite system (BDS) triple-frequency measurement data is used for experimental verification. The experiment results show that the GFPMP-PIR optimization combination model with wavelet denoising can detect and repair various cycle slips, especially for insensitive small cycle slips.
      PubDate: Fri, 22 Apr 2022 15:20:01 +000
       
  • Transportation of Payload Using Multiple Quadrotors via Rigid Connection

    • Abstract: Due to the limited payload capability of an aerial robot, multiple quadrotors can be used to manipulate payloads in aerial transportation, construction, and assembly tasks. This paper focuses on the cooperative transportation of a payload rigidly attached to multiple quadrotor bodies. These quadrotors may have different orientations. The dynamics equation of a rigid body in 3-D space is derived to describe the motion of such a transportation system. Robust position and attitude controllers are designed to drive the system to the desired pose. To assign control signals for each quadrotor, the control command allocation method compatible with the case that partial or all quadrotors are in parallel planes is developed. Finally, experimental results are presented to validate the effectiveness of the proposed controllers and control command allocation methods. Different from classical works in this field, this paper can solve the dynamics modeling, controller design, and control command allocation problems for the transportation of a rigidly connected payload using a team of quadrotors with different orientations.
      PubDate: Fri, 22 Apr 2022 14:50:02 +000
       
  • The Limitation Analysis of Two Dimensional Magnetic Field Configuration in
           Annular Ion Thruster

    • Abstract: In this paper, the limitations of two-dimensional magnetic field configuration for an annular ion thruster are analyzed theoretically and numerically. The two-dimensional magnetic field, which is commonly used in traditional ion thrusters, has been proved to be a very effective way for the confinement of primary electrons and ions. Hence, the confinement characteristics of primary electrons and ions in an annular ion thruster with the two-dimensional magnetic field configuration are first analyzed theoretically. Then, according to the analysis, a two-dimensional magnetic field for an annular ion thruster is designed. On this basis, the limitations of the two-dimensional magnetic field configuration are analyzed and discussed by a three-dimensional (3D) Particle-in-cell Monte Carlo collision (PIC-MCC) model. The results show that if the collision process is not considered, a uniform distribution of primary electrons can be achieved theoretically. However, when considering the collision process, the atom forms a significant impedance to the circumferential motion of primary electrons, thus greatly increasing the loss rate of primary electrons. Finally, it is found that, since primary electrons are not guided and constrained in the circumferential direction under the two-dimensional magnetic field, the discharge uniformity cannot be improved only by increasing the magnetic field intensity.
      PubDate: Thu, 21 Apr 2022 14:20:00 +000
       
  • A Fast Algorithm for Determining the Optimal Navigation Star for
           Responsive Launch Vehicles

    • Abstract: The platform inertial-stellar composite guidance is a composite guidance method supplemented by stellar correction on the basis of inertial navigation, which can effectively improve the accuracy of responsive launch vehicles. In order to solve the problem of rapid determining the optimal navigation star in the system, this paper proposes an algorithm based on the equivalent information compression theory. At first, this paper explains why the single-star scheme can achieve the same accuracy as the dual-star scheme. At the same time, the analytical expression of the optimal navigation star with significant initial error is derived. In addition, the available optimal navigation star determination strategy is also designed according to the arrow-borne navigation star database. The proposed algorithm is evaluated by two representative responsive launch vehicle trajectory simulations. The simulation results demonstrate that the proposed algorithm can determine the optimal navigation star quickly, which greatly shorten the preparation time before the rapid launch of vehicles and improve the composite guidance accuracy.
      PubDate: Tue, 19 Apr 2022 15:35:01 +000
       
  • PySCP: A Multiple-Phase Optimal Control Software Using Sequential Convex
           Programming

    • Abstract: Optimal control problems are common in aerospace engineering. A Python software program called PySCP is described for solving multiple-phase optimal control problems using sequential convex programming methods. By constructing a series of approximated second-order cone programming subproblems, PySCP approaches to the solution of the original optimal control problem in an iterative way. The key components of the software are described in detail, including convexification, discretization, and the adaptive trust region method. The convexification of the first-order differential dynamic equation is implemented using successive linearization. Six discretization methods, including zero-order hold, first-order hold, Runge-Kutta, and three hp pseudospectral collocation methods, are implemented so that different types of optimal control problems can be tackled efficiently. Adaptive trust region method is employed, and robust convergence is achieved. Both free-final-time problem and fixed-final-time problem can be solved by the software. The application of the software is demonstrated on three optimal control problems with varying complexity. PySCP provides researchers a useful toolkit to solve a wide variety of optimal control problems using sequential convex programming.
      PubDate: Wed, 13 Apr 2022 14:35:01 +000
       
  • Maneuver Strategy for Active Spacecraft to Avoid Space Debris and Return
           to the Original Orbit

    • Abstract: During normal operation of the on-orbit spacecraft, if some satellite in a nearby orbit suddenly breaks apart, its debris will threat the safe operation of the on-orbit spacecraft. Therefore, it is necessary to study the active spacecraft’s avoidance of the space debris group and returning to the original orbit. In this way, the safe operation of on-orbit spacecraft will be guaranteed. However, as the geometric structure of the space debris group is constantly changing, it is hard to accurately demonstrate the changing shape of the debris group, let alone determine the unreachable domain. Traditional obstacle avoidance problems involve low speed of the vehicle; so, the application of artificial potential field and particle swarm algorithms is suitable for such problems. However, these two methods are not applicable to the maneuver strategy of spacecraft with high initial velocity. Therefore, to help spacecraft avoid the space debris group, a new method is required. This paper has established a simplified model to simulate the unreachable domain of the space debris group. It has modified the artificial potential field (APF) method and particle swarm optimization algorithm, with an aim to help spacecraft avoid the space debris group and return to the original orbit. Based on the method, the paper has proposed a three-stage maneuver strategy for the spacecraft to avoid the debris. To show the effectiveness of the method, this paper has simulated an on-orbit spacecraft’s avoidance of the space debris group nearby and returning to its original orbit. Through simulation, the feasibility of the maneuver strategy for spacecraft in the geosynchronous orbit is evaluated. The simulation results show that the method proposed in this paper can effectively accomplish the task.
      PubDate: Wed, 13 Apr 2022 08:50:01 +000
       
  • The Reduced-Order Model for Droplet Drift of Aerial Spraying under Random
           Lateral Wind

    • Abstract: The droplet drift during aerial spraying process of oilseed rape, which is induced by complex flow field including random lateral wind, is difficult to predict and suppress. In this study, the high-fidelity computational fluid dynamics (CFD) technique is employed to simulate the two-phase flow of droplets in the rotor flow field, and the influence of main operation parameters on spraying effect is investigated numerically. Furthermore, the mechanism of droplet deposition in various operation conditions is discussed according to the analysis of unsteady flow field characteristics. However, the simulation via CFD technique is time-consuming, and it is not suitable for multidisciplinary work and optimization design. To address such issue, a filter white Gaussian noise signal is used to mimic the random lateral wind, and the droplet drift distance is obtained numerically. Based on the input and output dataset of CFD, the recursive algorithm including nonlinear autoregressive exogenous model and surrogate-based recurrence framework and the deep learning method for time-series prediction called long short-term memory neural network are used to build the efficient reduced-order model, respectively. Numerical simulations show that the droplet drift distance can be predicted by measurable lateral wind speed via the reduced-order model approach, which agreed well with the results obtained via the CFD method. In addition, the reduced-order model could decrease computation cost by 6 orders of magnitude with an acceptable accuracy, which indicates that the proposed method could be used for the design of off-line closed-loop controller of a variable spraying system.
      PubDate: Tue, 12 Apr 2022 14:20:03 +000
       
  • Autonomous Phase Control Combining EKF and Adaptive Neural Network for
           Remote Sensing Satellites

    • Abstract: In this paper, a novel, effective, and feasible autonomous phase control algorithm based on the extended Kalman filtering (EKF) and neural network is firstly developed for addressing the problems of configuration maintenance of remote sensing satellite constellation. A balanced moment arm optimization method is employed to design the installation structure layout of the chemical propulsion system in the satellite. On that basis, an autonomous orbit control strategy is presented for controlling the phase of satellites, and the EKF algorithm is utilized to determine the orbit used to calculate the satellite phase. A radial basis function (RBF) neural network-based attitude control method is proposed to solve the attitude disturbance problem in the course of the phase control, and the RBF neural network is utilized to approximate the coupling torque of the orbit control. The simulation results demonstrate the feasibility of the designed automatic phase control strategy of the satellite.
      PubDate: Tue, 12 Apr 2022 13:05:03 +000
       
  • Reconstruction of Wing Structure Deformation Based on Particle Swarm
           Optimization Ridge Regression

    • Abstract: In this paper, a typical airfoil aluminum plate structure is taken as the research object. A structural deformation monitoring and reconstruction method, PSO-RR (particle swarm optimization-ridge regression) algorithm, is proposed. A variety of different complex load cases are applied to the airfoil structure, and the strain values at some specific positions of the structure are collected. The ridge regression algorithm is used to construct the theoretical model of the relationship between the strain and structural deformation. Then, the structural displacements with different load cases are monitored and reconstructed. To improve the precision, the PSO algorithm is used to optimize the ridge regression parameters and comparative analysis is carried out with the typical structural deformation reconstruction algorithm, such as the KO theoretical method. Results show that the PSO-RR predicts the deformation of complex wing structures under different kinds of complex load cases accurately. This method, which has high precision, does not depend on the specific structures and load cases.
      PubDate: Tue, 12 Apr 2022 12:50:01 +000
       
  • Mitigation Measures for Windfarm Effects on Radar Systems

    • Abstract: Windfarms can have a significant impact on radar systems, especially air surveillance radar. This is because it is usually designed to show only moving targets and cancel out stationary objects. However, the rotation of wind turbine blades can be detected by radar as a false flight or target. Clutter or interference caused by windfarms can reduce radar sensitivity in critical regions, making real targets disappear. This could in turn affect the deployment of windfarms and lead to the cancellation of future renewable energy projects and plans. This paper presents the different strategies and techniques used to mitigate the windfarm impact on radar systems. Precisely, we aim throughout this article to classify the main currently adopted approaches, view the recent trends and research directions in this field, and try to trace the advantages and drawbacks along with the challenges of deploying such schemes.
      PubDate: Mon, 11 Apr 2022 13:05:03 +000
       
  • The Aerodynamic Characteristics of a Diamond Joined-Wing Morphing Aircraft

    • Abstract: This paper presents a new-concept aircraft with a diamond joined-wing morphing configuration, which simultaneously adjusts the sweep angles of both the front wing and rear wings by a telescopic support rod. The compressible Navier-Stokes equations in the conservative form are solved to analyze the configuration characteristics and the aerodynamic benefits of this aircraft with different values of sweep angle (15°, 60°) and Mach number. The maximum lift-to-drag ratio is about 13.5 at and , 12.8 at and , and 3.4 at and , respectively. Compared with traditional morphing aircraft, the main advantages of this configuration include better transonic and supersonic performance, better lift characteristics in the state of a high-aspect ratio, and lower zero-lift drag in the supersonic state. The lift ratio of the front and rear wings shows a good similarity at different Mach numbers, especially for the 15° model, and the value eventually tends to be 1.3 at . Meanwhile, the flow field characteristics and interference characteristics of the front and rear wings are studied. The increase in the angle of attack, incoming flow velocity, and distance between the front and rear wings can reduce the interference between front and rear wings. The influence from upstream components is proven to improve the aerodynamic characteristics of the rear wing, especially at .
      PubDate: Mon, 11 Apr 2022 09:20:01 +000
       
  • Prescribed Performance Adaptive Control for a Nonlinear Aeroelastic System
           with Input Constraint

    • Abstract: A constrained prescribed performance compensation controller is proposed for a nonlinear aeroelastic system in the presence of wind gust, system uncertainties, and input saturation. To deal with the effects of the nonsmooth saturation nonlinearity, an approximate saturation function is introduced into the controller design, which can smoothly approximate the real saturation with arbitrarily prescribed precision. Specifically, by designing the prescribed performance function, a fixed-time control framework is designed to ensure that the closed-loop system has the prescribed tracking performance. The designed control algorithm can not only compensate the adverse effect caused by disturbances and uncertainties but also restrain the excessive amplitude of control input. Finally, the stability analysis shows that all the signals in the closed-loop system are semiglobally uniformly ultimately bounded via the Lyapunov stability analysis method, and simulation results are presented to demonstrate the feasibility and effectiveness of the proposed method.
      PubDate: Fri, 01 Apr 2022 13:50:01 +000
       
  • Beacon Aided Positioning Method for Lunar Probes Using Temporal
           Interferometry

    • Abstract: With a series of complex lunar exploration missions carried out, reliable autonomous navigation approaches for lunar probes are in demand. In this paper, aiming to obtain the position of the probes with high accuracy and computational efficiency, a novel passive positioning scheme for lunar probes is presented. We first designed a reference system including four beacons with known positions. Then, we proposed arctangent temporal interferometry (ATI) method for ambiguity resolution in displacement measurement. Moreover, the quad-beacon displacement search (QBDS) algorithm is proposed for 2-dimension (2D) position search, which enables accurate and computational-efficient 2D positioning for lunar probes. The simulation validations show the effectiveness of the proposed positioning scheme and algorithms.
      PubDate: Wed, 30 Mar 2022 12:05:01 +000
       
  • Dynamic Surface Control with High-Order LESO Compensation for Near-Space
           Vehicle

    • Abstract: Aimed at the flight control problem of a near-space vehicle (NSV) with uncertainties such as parameter perturbation and external disturbance, a novel dynamic surface control (DSC) method with high-order linear extended state observer (HLESO) compensation is proposed in this paper. In the proposed method, a tracking differentiator (TD) based on an inverse hyperbolic sine function is firstly designed, and the convergence of TD is also analysed with the Lyapunov stability theory. Furthermore, the numerical simulations are detailed to demonstrate the superiority of the proposed TD compared with others. Then, a dynamic surface controller based on the traditional backstepping control technique is designed, where the TD is adopted to obtain the differential signal of the virtual control law, in order to solve the “differential expansion,” and the HLESO is adopted to accurately estimate the “lumped disturbance” so as to realize the dynamic compensation of the controller and enhance the disturbance suppression ability of the system. The simulation results demonstrate the validity of the proposed method.
      PubDate: Mon, 28 Mar 2022 13:20:02 +000
       
  • Numerical Simulation of Aircraft Icing with an Unsteady Thermodynamic
           Model considering the Development of Water Film and Ice Layer

    • Abstract: Considering the transient heat and mass transfer process of the impinged water droplets during aircraft icing, an unsteady thermodynamic model was established to simulate the dynamic developments of the water film and the ice layer on aircraft surfaces. The unsteady model was discretized in an implicit scheme with a corresponding solution method. Icing simulations were performed for a NACA0012 airfoil, and the results show acceptable agreement with the data in the literature. Water film first appears near the stagnation point, and then, the film thickness increases, and the runback water region expands with time, affecting the icing rate, the surface temperature, and the ice type. The development of the water film is rapid, and the thickness and range of the film, along with the icing rate, reach a steady state in a short time. The stable characteristics obtained by the unsteady model are consistent with those of the Messinger steady model. Despite that the unsteady and steady models can obtain similar ice shapes in icing simulations, the dynamic developments of the water film and the ice layer should be considered at the initial stage of ice accretion or in the short-time icing simulations.
      PubDate: Tue, 22 Mar 2022 11:50:04 +000
       
  • On High-Dimensional Time-Variant Reliability Analysis with the Maximum
           Entropy Principle

    • Abstract: The structural reliability analysis suffers from the curse of dimensionality if the associated limit state function involves a large number of inputs. This study develops a reliability analysis method that deals with high-dimensional inputs over time. The probability distribution of the structural response is reconstructed by the maximum entropy principle which is achieved by solving an optimization problem derived from the concept of relative entropy. The optimization problem is transformed into a convex one with respect to the orders of fractional moments and the Lagrange multipliers. Additionally, considering the associated computational issues, it is reformulated with side constraints on the parameters of the maximum entropy distribution. Then, a global optimization procedure is performed. The proposed method is successfully applied to the reliability analysis of a linear and a nonlinear structural system, which involves a large number of inputs deriving from the discretization of the input random processes.
      PubDate: Sat, 19 Mar 2022 07:50:03 +000
       
  • Design and Analysis of Direct Abort Orbits in the Earth-Moon Transfer
           Phase of Crewed Lunar Exploration Missions

    • Abstract: A direct abort orbit design method is presented for direct abort missions in the Earth-Moon transfer phase of crewed lunar exploration missions. First, according to the demand of an emergency rescue in the Earth-Moon transfer phase, two direct abort orbit schemes are introduced. Then, a serial orbit design method is proposed for a high-fidelity direct abort orbit. An analytical model is established for the calculation of initial values, and the optimization design is performed in the high-fidelity orbit model to determine a single-impulse abort orbit. A hybrid optimization design process is proposed to generate a two-impulse abort orbit. The results of simulation examples verify the validity and feasibility of the proposed direct abort orbit design method. Finally, extensive simulations are carried out to analyze the characteristics of abort impulse and abort return time and reveal the general rules of direct abort orbits. The research conclusions can provide a reference for the design of emergency rescue schemes in future crewed lunar exploration missions.
      PubDate: Sat, 19 Mar 2022 07:35:01 +000
       
  • Numerical Investigation of Contact Burning in an Air-Breathing Continuous
           Rotating Detonation Engine

    • Abstract: Three-dimensional (3D) numerical simulations of a continuous rotating detonation engine are carried out with an unsteady Reynolds-averaged Navier-Stokes solver. The second-order upwind advection upstream splitting method and second-order Runge-Kutta method are used to discretize space and time terms, and detailed 9-species 19-step hydrogen-oxygen reactions are applied in this study. Nonpremixed rotating detonation is successfully realized numerically, and the characteristics of the detonation wave are revealed. The expanding angle of the combustor has a great impact on the shape of the detonation wave but has little influence on the propagation velocity. The evolution of combustion on the contact region is analyzed in detail; a more accurate schematic of non-premixed air-breathing rotating detonation engines is given in this paper. A rough analysis of the heat performance of the contact region shows that the heat release of the contact region is approximately one-third of the total heat release and the configurations of the combustors do not affect the proportion.
      PubDate: Sat, 19 Mar 2022 07:35:01 +000
       
  • Effects of the Air Inlet Angle on the Combustion and Ablation Environment
           of a Hybrid Powder-Solid Ramjet

    • Abstract: A hybrid powder-solid ramjet (HPSR) that combined the advantages of a solid rocket ramjet (SRJ) and a powder ramjet engine was investigated in this research. To improve the combustion efficiency and optimize the inner wall thermal protection of the afterburner, the effects of the air inlet angle on the combustion and wall ablation environment were studied. The standard - model, the eddy-dissipation model (EDM), and the boron particle ignition and combustion model were adopted to simulate the two-phase flow in the afterburners with different air inlet angles (45°, 60°, 75°, and 90°). The results showed that the global flow field and the distribution of the vortexes in the afterburner that had a significant influence on the ablation environment of the inner wall and the combustion efficiency were determined by the impact effect and the squeezing effect of the ram air on the primary fuel gas, which was affected by the air inlet angle. As the air inlet angle increased, the total combustion efficiency of the four cases first increased and then decreased, reaching 80.38%, 81.64%, 84.34%, and 83.26% for angles of 45°, 60°, 75°, and 90°, respectively. At the same time, the inner wall ablation became more severe because both the erosion effect of the condensed phase particles and the gas-flow scouring effect were enhanced, and a large temperature gradient was generated on the inner wall. The study results can provide a reference for designing the air inlet angle of an HPSR.
      PubDate: Fri, 18 Mar 2022 14:05:02 +000
       
  • Robust Data-Driven Fault Detection: An Application to Aircraft Air Data
           Sensors

    • Abstract: Fault detection (FD) is important for health monitoring and safe operation of dynamical systems. Previous studies use model-based approaches which are sensitive to system specifics, attenuating the robustness. Data-driven methods have claimed accurate performances which scale well to different cases, but the algorithmic structures and enclosed operations are “black,” jeopardizing its robustness. To address these issues, exemplifying the FD problem of aircraft air data sensors, we explore to develop a robust (accurate, scalable, explainable, and interpretable) FD scheme using a typical data-driven method, i.e., deep neural networks (DNN). To guarantee the scalability, aircraft inertial reference unit measurements are adopted as equivalent inputs to the DNN, and a database associated with 6 different aircraft/flight conditions is constructed. Convolutional neural networks (CNN) and long-short time memory (LSTM) blocks are used in the DNN scheme for accurate FD performances. To enhance robustness of the DNN, we also develop two new concepts: “large structure” which corresponds to the parameters that can be objectively optimized (e.g., CNN kernel size) via certain metrics (e.g., accuracy) and “small structure” that conveys subjective understanding of humans (e.g., class activation mapping in CNN) within a certain context (e.g., object detection). We illustrate the optimization process we adopted in devising the DNN large structure, which yields accurate (90%) and scalable (24 diverse cases) performances. We also interpret the DNN small structure via class activation mapping, which yields promising results and solidifies the robustness of DNN. Lessons and experiences we learned are also summarized in the paper, which we believe is instructive for addressing the FD problems in other similar fields.
      PubDate: Wed, 16 Mar 2022 17:05:01 +000
       
 
JournalTOCs
School of Mathematical and Computer Sciences
Heriot-Watt University
Edinburgh, EH14 4AS, UK
Email: journaltocs@hw.ac.uk
Tel: +00 44 (0)131 4513762
 


Your IP address: 3.236.234.223
 
Home (Search)
API
About JournalTOCs
News (blog, publications)
JournalTOCs on Twitter   JournalTOCs on Facebook

JournalTOCs © 2009-