Subjects -> AERONAUTICS AND SPACE FLIGHT (Total: 120 journals)
 Showing 1 - 30 of 30 Journals sorted by number of followers AIAA Journal       (Followers: 1191) SpaceNews       (Followers: 825) Journal of Spacecraft and Rockets       (Followers: 771) Journal of Propulsion and Power       (Followers: 610) Acta Astronautica       (Followers: 495) Advances in Space Research       (Followers: 457) Aviation Week       (Followers: 437) Aerospace Science and Technology       (Followers: 427) IEEE Transactions on Aerospace and Electronic Systems       (Followers: 384) Journal of Aircraft       (Followers: 335) Control Systems       (Followers: 314) IEEE Aerospace and Electronic Systems Magazine       (Followers: 282) Journal of Navigation       (Followers: 278) Aircraft Engineering and Aerospace Technology       (Followers: 261) Gyroscopy and Navigation       (Followers: 258) Journal of Guidance, Control, and Dynamics       (Followers: 204) Space Science International       (Followers: 200) Space Science Reviews       (Followers: 97) International Journal of Aerospace Engineering       (Followers: 82) Progress in Aerospace Sciences       (Followers: 80) Advances in Aerospace Engineering       (Followers: 69) Journal of Aerospace Engineering       (Followers: 69) Propulsion and Power Research       (Followers: 68) Aerospace       (Followers: 60) Space Safety Magazine       (Followers: 51) Space Research Today       (Followers: 48) Proceedings of the Institution of Mechanical Engineers Part G: Journal of Aerospace Engineering       (Followers: 46) International Journal of Aeroacoustics       (Followers: 40) IEEE Transactions on Circuits and Systems I: Regular Papers       (Followers: 39) International Journal of Aerodynamics       (Followers: 37) Canadian Aeronautics and Space Journal       (Followers: 34) Journal of Aerospace Information Systems       (Followers: 34) International Journal of Aerospace Sciences       (Followers: 32) Journal of Aeronautics & Aerospace Engineering       (Followers: 31) Space Policy       (Followers: 30) CEAS Aeronautical Journal       (Followers: 29) Journal of Space Weather and Space Climate       (Followers: 27) Aviation Psychology and Applied Human Factors       (Followers: 27) Russian Aeronautics (Iz VUZ)       (Followers: 24) Egyptian Journal of Remote Sensing and Space Science       (Followers: 24) Artificial Satellites       (Followers: 23) International Journal of Aerospace Psychology       (Followers: 23) Journal of Aerospace Information Systems       (Followers: 22) Annual of Navigation       (Followers: 22) Chinese Journal of Aeronautics       (Followers: 21) Nonlinear Dynamics       (Followers: 20) Aerospace Medicine and Human Performance       (Followers: 19) Journal of Aerospace Engineering & Technology       (Followers: 18) Journal of Aerodynamics       (Followers: 18) Aerospace Scientific Journal       (Followers: 18) Journal of Wind Engineering and Industrial Aerodynamics       (Followers: 17) Aviation       (Followers: 17) International Journal of Space Structures       (Followers: 17) Research & Reviews : Journal of Space Science & Technology       (Followers: 17) Proceedings of the Human Factors and Ergonomics Society Annual Meeting       (Followers: 16) Fatigue of Aircraft Structures       (Followers: 15) International Journal of Satellite Communications Policy and Management       (Followers: 13) Frontiers in Astronomy and Space Sciences       (Followers: 12) Elsevier Astrodynamics Series       (Followers: 12) Aeronautical Journal, The       (Followers: 12) International Journal of Crashworthiness       (Followers: 12) Journal of Airline and Airport Management       (Followers: 12) International Journal of Micro Air Vehicles       (Followers: 11) Journal of Aviation Technology and Engineering       (Followers: 11) International Journal of Space Science and Engineering       (Followers: 11) Air Force Magazine       (Followers: 11) COSPAR Colloquia Series       (Followers: 11) International Journal of Space Technology Management and Innovation       (Followers: 10) Aviation in Focus - Journal of Aeronautical Sciences       (Followers: 10) Journal of Aircraft and Spacecraft Technology       (Followers: 9) Population Space and Place       (Followers: 9) Journal of Aeronautical Materials       (Followers: 9) International Journal of Aviation Management       (Followers: 9) Transportmetrica A : Transport Science       (Followers: 9) Journal of the Astronautical Sciences       (Followers: 9) Advances in Aerospace Science and Technology       (Followers: 8) Air Medical Journal       (Followers: 8) Journal of Space Safety Engineering       (Followers: 8) International Journal of Aviation Technology, Engineering and Management       (Followers: 7) Journal of the American Helicopter Society       (Followers: 7) Journal of Aerospace Technology and Management       (Followers: 7) International Journal of Applied Geospatial Research       (Followers: 7) New Space       (Followers: 6) Aerospace Systems       (Followers: 6) International Journal of Turbo and Jet-Engines       (Followers: 6) RocketSTEM       (Followers: 6) Civil Aviation High Technologies       (Followers: 5) International Journal of Aviation, Aeronautics, and Aerospace       (Followers: 5) REACH - Reviews in Human Space Exploration       (Followers: 5) International Journal of Sustainable Aviation       (Followers: 5) Aviation Advances & Maintenance       (Followers: 5) Cosmic Research       (Followers: 5) Unmanned Systems       (Followers: 5) Space and Polity       (Followers: 4) Life Sciences in Space Research       (Followers: 4) Aerotecnica Missili & Spazio : Journal of Aerospace Science, Technologies & Systems       (Followers: 4) Astrodynamics       (Followers: 4) Investigación Pecuaria       (Followers: 3) Aerospace technic and technology       (Followers: 3) Journal of Spatial Science       (Followers: 3) ASTRA Proceedings       (Followers: 3) Journal of KONBiN       (Followers: 3) Problemy Mechatroniki. Uzbrojenie, lotnictwo, inżynieria bezpieczeństwa / Problems of Mechatronics. Armament, Aviation, Safety Engineering       (Followers: 3) npj Microgravity       (Followers: 3) Journal of Astrobiology & Outreach       (Followers: 3) Journal of Aviation/Aerospace Education & Research       (Followers: 2) IEEE Journal on Miniaturization for Air and Space Systems       (Followers: 2) Microgravity Science and Technology       (Followers: 2) Вісник Національного Авіаційного Університету       (Followers: 2) International Journal of Aeronautical and Space Sciences       (Followers: 2) Ciencia y Poder Aéreo       (Followers: 2) MAD - Magazine of Aviation Development       (Followers: 2) Journal of the Australasian Society of Aerospace Medicine       (Followers: 1) Open Aerospace Engineering Journal       (Followers: 1) Advances in Astronautics Science and Technology       (Followers: 1) Journal of Engineering and Technological Sciences       (Followers: 1) Technical Soaring       (Followers: 1) Spatial Information Research       (Followers: 1) Mekanika : Jurnal Teknik Mesin i       (Followers: 1) Perspectives of Earth and Space Scientists i
Similar Journals
 Aerospace SystemsNumber of Followers: 6      Hybrid journal (It can contain Open Access articles) ISSN (Print) 2523-3947 - ISSN (Online) 2523-3955 Published by Springer-Verlag  [2653 journals]
• Multiband image fusion using total generalized variation regularization
• Abstract: Multiband image fusion has become a thriving area of research in a number of different fields, such as space robotics, and remote sensing, etc. Many multiband image fusion methods have been proposed for hyperspectral sharpening with panchromatic images, hyperspectral sharpening with multispectral images and panchromatic images, etc. Despite the different motivations, we observe that many existing methods possibly lead to over-smooth regions. In this work, we consider a new problem formulation of two image fusion problems. A novel fusion model with total generalized variation regularization term is proposed, where the fusion process is performed on hybrid gradient domains. The optimization framework of alternating direction multiplier of method is used to solve the resulting problem. In an extensive evaluation, our method outperforms some state-of-the-art methods.
PubDate: 2021-03-04

• Attitude control strategy of airship based on active disturbance rejection
controller
• Abstract: The flight performance of the airship is closely related to the attitude control. For the stability of the station-keeping and the rapidity and accuracy of the trajectory tracking, it is necessary to study the attitude control of the airship. This paper proposes a strategy including two parties. First, a novel control mechanism combining moving-mass and tail vector thrust is proposed, and the airship mathematical model is introduced briefly. Second, active disturbance rejection controller (ADRC) is introduced which is developed from classical proportion–integration–differentiation (PID) controller. Considering the special working environment of stratospheric airship, the wind field is added to the simulation as external disturbance. The results show that the system is stable which can track any expected angle of pitch and yaw directions with small overshoot and rise time. In general, with or without the disturbance of 4 m/s wind field, the ADRC performs better than PID controller.
PubDate: 2021-03-01

• Characterization and mitigation of multipath fading on multi-frequency
GNSS signals in urban environment
• Abstract: The global navigation satellite systems (GNSS) receiver is likely to experience performance degradation in the presence of multipath interferences in indoor and urban canyon environments. There will be multiple reflected signals arriving at the receiver antenna from different paths and directions regarding the different locations of the nearby constructions, causing significant fluctuations and distortions on the amplitude and phase of the direct signals. This is the so-called multipath fading effects and usually exhibit with the random features of temporal, spatial, and frequency diversity across the signal bands. To have a better understanding of the multipath fading effects, a live test was conducted near Lujiazui CBD area in Shanghai. The collected data were processed to characterize the signal attenuations and phase fluctuations on multi-frequency GNSS signals via the detrend code delay, carrier phase, and navigation bit errors. The resulting scintillation index on amplitude, code delay, and carrier phase, e.g., S4, $${\sigma }_{\varphi }$$ and $${\sigma }_{\tau }$$ can be calculated. Based on these multipath features, the inter-frequency aiding strategy will be utilized for the multipath mitigations in the multi-frequency tracking loop design. The results demonstrate the effectiveness of the multi-frequency tracking algorithm in the urban environment.
PubDate: 2021-03-01

• Spatio-temporal graph convolutional neural network for remaining useful
life estimation of aircraft engines
• Abstract: Accurate remaining useful life (RUL) estimation is crucial for the maintenance of complex systems, e.g. aircraft engines. Thanks to the popularity of sensors, data-driven methods are widely used to evaluate RULs of systems especially deep learning approaches. Though remarkably capable at non-linear modeling, deep learning-based prognostics techniques lack powerful spatio-temporal learning ability. For instance, convolutional neural networks are restricted to only process grid structures rather than general domains, recurrent neural networks neglect spatial relations between sensors and suffer from long-term dependency learning. To solve these problems, we construct a graph structure on sensor network with Pearson Correlation Coefficients among sensors and propose a method for combining the power of graph convolutional network on spatial learning and sequence learning success of temporal convolutional networks. We conduct the proposed method on aircraft engine dataset provided by NASA. The experimental results demonstrate that the established graph structure is appropriate and the proposed approach can model spatio-temporal dependency accurately as well as improve the performance of RUL estimation.
PubDate: 2021-03-01

• Adaptive fading factor unscented Kalman filter with application to target
tracking
• Abstract: One purpose of target tracking is to estimate the states of targets, and unscented Kalman filter is one of the effective algorithms for estimating in the nonlinear tracking problem. Considering the characteristics of complex maneuverability, it is easy to reduce the tracking accuracy and cause divergence due to the mismatch between the system model and the practical target motion model. Adaptive fading factor is an effective counter to this problem, having been instrumental in solving accuracy and divergence problems. Fading factor can adaptively adjust covariance matrix online to compensate model mismatch error. Moreover, fading factor not only improves the filtering accuracy, but also automatically adjusts the error covariance in response to the different situation. The simulation results show that the adaptive fading factor unscented Kalman filter has more advantages in target tracking and it can be better applied to nonlinear target tracking.
PubDate: 2021-03-01

• Substantiation of choosing rational appearance of nose of aircraft with
the use of mathematical modeling
• Abstract: As part of this work, a comprehensive analysis of the question of ensuring the specified aerodynamic performance of the aircraft required to implement a cruising supersonic flight at M ~ 1.5. B Analysis of possible methods of aerodynamic performance evaluation (AP) of aircraft components in the course of optimization of their geometrical parameters to achieve a minimum contribution to the AP. The paper presents an algorithm for the formation of the nose part of the aircraft of minimal aerodynamic resistance, and also selects criteria for evaluation of the nose part of the aircraft as an element of the glider, which has a significant contribution to the overall aircraft AP at a flight speed of $$M>1$$ . The results of this work can be used at the early stages of aircraft tying up to reduce the time required for the formation of a mathematical model of the surface of a prospective aircraft.
PubDate: 2021-02-22

• PBN operation advantage analysis over conventional navigation
• Abstract: With the development of global economy and the rapid growth of people's material demand, the sustainable development of air industry needs more and more airspace capacity, so the importance of optimizing available airspace is prominent. Under the background of world aviation industry, after more than 60 years development, the safety level has steadily improved, the total amount of transportation has increased rapidly, the air routes have been enriched and the air traffic capacity has gradually improved. PBN, the performance-based navigation technology is one of the most essential topics in China’s aviation development. Compared to conventional navigation, it has witnessed significant benefit in PBN operation, such as less fuel cost, shorter route range and lighter workload of the controllers. This paper introduces the basic concept of PBN, and then selects three typical routes through simulation software, compares the characteristics of PBN and traditional navigation in practice, and illustrates the advantages of PBN procedures by means of data and charts.
PubDate: 2021-02-19

• An enhanced situational awareness design for airborne surveillance based
on Automatic Dependent Surveillance–Broadcast
• Abstract: With the fast growth of general aviation, Automatic Dependent Surveillance–Broadcast (ADS-B) becomes the direction of airspace surveillance development. The previous researches in surveillance field have managed to use ADS-B data to improve the performance of the integrated surveillance system, yet they have failed to consider ADS-B as a major source of data and will not be applicable when the general aviation is growing fast. The research of this paper proposes an enhanced situational awareness design based on ADS-B. With elective fusion based on surveillance quality, it helps to improve the performance when ADS-B data are taken as a major source of surveillance data. Several simulation scenarios with different surveillance quality are tested. The results show that the error is reduced and the overall surveillance performance is improved when surveillance quality is low. An integrated display is built for enhanced situational awareness display afterwards. With this enhanced situational awareness design, the pilots can be provided with a more comprehensive awareness of the airspace including general aviation aircrafts.
PubDate: 2021-02-01
DOI: 10.1007/s42401-020-00081-8

• Harmonic balance analysis and simulations of spacecraft rendezvous and
formation flying dynamics
• Abstract: In this paper, approximated nonlinear spacecraft relative motion model is developed via Euler Lagrange approach using local vertical–local horizontal frame attached to the chief spacecraft. Harmonic balance analysis approach, a powerful technique for approximating nonlinear equation and generating periodic solutions, is applied to the approximated nonlinear relative motion for the development of new linear harmonic balance approximation model and investigation of its periodic solutions. Using power series method, power series approximate solutions of the harmonically balanced model of the relative motion are developed. Furthermore, the computational algorithm employed for the orbit propagation of nonlinear, harmonic balance and Clohessy–Wilshire models is presented. Using MATLAB ODE45 integrator, the relative motion models are numerically integrated and propagated. The numerical results show that harmonic balance model gave a better approximation of the nonlinear model.
PubDate: 2021-02-01
DOI: 10.1007/s42401-021-00083-0

• Application of mathematical modeling to solve the emergency water landing
task in the interests of passenger aircraft certification
• Abstract: The article deals with issues related to the application of modeling in the interests of aircraft certification. The technique of numerical flood modeling based on the numerical solution of Navier–Stokes equations with a free surface is proposed. Verification of the technique was carried out on the tasks about water fluctuations in the tank under the action of gravity, cylinder movement in the liquid and ball drop in the liquid. In all cases, good convergence of simulation results with experimental data is shown. Validation of the method was performed on the task of sinking the vessel model with damage in the bottom and on board. Complex model hull movements were studied due to changing buoyancy properties as a result of water leakage inside the hull during the sinking. Comparison of calculated and experimental data shows their qualitative and quantitative consistency at the initial stage of the dive. By the example of modeling the flooding of the passenger aircraft model, the practical application of the developed method for certification is shown. It was found that at the initial moment of time after an unplanned landing on the water, the front and rear emergency exits are located above the waterline, and the buoyancy time of the aircraft is sufficient for its emergency exit.
PubDate: 2021-02-01
DOI: 10.1007/s42401-020-00082-7

• Effect of tip injection on the flow characteristics of an aeroengine
compressor rotor
• Abstract: Existing experiments, simulations, and analysis have shown that the flow field of the blade tip has a significant effect on rotating stall and acoustic resonance in aeroengine compressors. Based on the numerical simulation of NASA rotor 37, the steady influence of air injection at blade tip was investigated in this investigation. The results show that the injected flow could obviously extend the stability margin of the axial compressor to varying degrees. The tip injection reduces the blockage caused by the tip leakage, and reduces the backflow in the trailing edge area of the blade tip, thereby delaying the occurrence of stall. Furthermore, in this paper, different types of rotors are constructed to verify the effect of injection parameters on the stability extension. The results show that the improvement of rotor stall margin is positively correlated with the injector inlet total pressure, and when the injector inlet flow conditions are of the same magnitude, the improvement of the rotor stall margin is negatively related to the distance between the injector and the leading edge of the blade.
PubDate: 2021-01-14
DOI: 10.1007/s42401-020-00078-3

• Adaptive filter based on Monte Carlo method to improve the non-linear
target tracking in the radar system
• Abstract: This article deals with the problem of degraded tracking performance of a high non-linear target in a radar system, well known by the divergence phenomenon. In our study, we aim to improve the target state estimation to imitate the tracking scenario as well as avoid the last cited undesirable phenomenon, generated during the non-linear measurements filtering, once using extended KALMAN filter. To overcome this issue, we have implemented a new approach based on the adaptive Monte Carlo (AMC) algorithm to replace the traditional method as is known by the extended KALMAN filter (EKF). The obtained experimental results showed a challenging remediation. Where, the AMC converges towards the accurate state estimation. Thus, more efficient than extended KALMAN filter. The experimental results prove that the designed system meets the objectives set for AMC referring to an experimental database obtained by a radar system, using MATLAB software development framework.
PubDate: 2021-01-14
DOI: 10.1007/s42401-020-00080-9

• Aerial image detection and recognition system based on deep neural network
• Abstract: Aerial image detection aims to find objects of interest and give their locations, and the goal of aerial image recognition is to classify the scenes or objects. Deep neural network is by far the best model for image detection and recognition. But still it fails to meet the requirements of high precision and low missing alarm. To solve this issue, we propose a two-step system including detection and fine-grained recognition modules. The first module is based on one-stage detection method YOLOv3. Furthermore, the metric-learning-based magnet loss is introduced to realize fine-grain recognition in the second step. The experiments prove the effectiveness of their combinations on improving precision and reducing missing alarm rate.
PubDate: 2021-01-03
DOI: 10.1007/s42401-020-00077-4

• Analysis of BDS GEO satellite multipath effect for GNSS integrity
monitoring in civil aviation
• Abstract: With the great development of Global Navigation Satellite System (GNSS), multi-GNSS constellations (GPS, BDS, GLONASS, and Galileo) are able to provide users with more accurate positioning result. For civil aviation, to guarantee user’s safety, multi-constellation GNSS needs to meet the integrity requirement. Using conservative error models, Multiple Hypothesis Solution Separation (MHSS) Advanced Receiver Autonomous Integrity Monitoring (ARAIM) is proposed to evaluate GNSS integrity. Current multipath error model in ARAIM algorithm is based on data of GPS Medium Earth Orbit (MEO) satellites. But BDS is a hybrid constellation. For BDS II, there has 5 Geosynchronous Earth Orbit (GEO) satellites. Previous studies have shown that the multipath effect of GEO satellites has statistical characteristics different from MEO satellites. Meanwhile, the multipath magnitude of GEO satellites is larger than that of MEO satellites. This paper mainly focuses on validating whether the multipath error model in ARAIM algorithm is conservative enough for GEO satellites. In this paper, Code Minus Carrier (CMC) residuals are calculated for BDS GEO dual-frequency signals. Then the Standard Deviation (STD) of CMC residuals can be conservatively estimated by bounded Cumulative Distribution Function (CDF). After eliminating interference from receiver noise, STD of GEO multipath can be obtained. Comparing the STD of GEO multipath effect with ARAIM multipath error model, a conclusion could be drawn that current multipath error model in ARAIM algorithm is no longer able to conservatively estimate the statistical characteristics of GEO satellites.
PubDate: 2021-01-02
DOI: 10.1007/s42401-020-00074-7

• Behavior of mixing enhancement in microscale shock cylindrical bubble
interaction
• Abstract: The investigation in the mixing characteristics of microscale shock cylindrical bubble interaction (SBI) provides a fundamental perspective into the microscale fuel injection. In present paper, the mixing performance of multi-scale SBI is numerically studied based on compressible Navier–Stokes equation. Starting from the bubble morphology, a scaling behavior of concentration distribution is exhibited in macroscale dynamics, whereas a superior capability of concentration decaying is observed in microscale cases. On the basis of mixedness evaluation, the mixing property of microscale bubbles is reinforced in the pre-interaction stage with notable viscous diffusion, and suppressed in the later evolution in the absence of vortex formation. Resorting to the Lagrangian coherent structure, a spatial coincidence between fluid stretching and mixing extent is visualized. The present study attempts to clarify the physical rationality of microscale injection strategies such as the atomization process and multiple micro-nozzles for mixing enhancement. Further efforts are devoted to physically modelling the competing mechanism of stirring effect (macroscale dynamics) and viscous diffusion (microscale dynamics) for optimal mixing performance.
PubDate: 2021-01-02
DOI: 10.1007/s42401-020-00076-5

• Analysis and experimental study on different airfoils in heavy unmanned
aerial vehicle
• Abstract: The performance of airfoil plays an important role in the performance of model aircraft. Three types of airfoils are selected in this paper: the GOE 480, MH 114, and MH 115, which are all flat-convex airfoils. Firstly, three types of airfoil were numerically analyzed by using Profili software. The results show that among the three types of flat-convex airfoils, the lift-drag ratio of MH series airfoils is higher than that of GOE 480. Then, the FEA software was used to analyze the aerodynamic performance of the wings. And the lift and drag coefficient obtained from calculation was compared with the results by Profili software. To compare the actual flight performance of the three airfoils, the control variable method and UAV self speed measurement method based on sequence images were used for the real field test. The results show that the type of MH 115 has the largest max level speed among the three types of wings.
PubDate: 2020-11-20
DOI: 10.1007/s42401-020-00072-9

• State-based safety analysis method for dynamic evaluation of failure
effect
• Abstract: System state that represents a combined influence of internal and external system parameters on the overall failure effect plays a significant role in failure effect analysis. The traditional safety analysis methods can hardly evaluate the overall failure impact due to the dynamic failure behaviors in diverse system interaction situations. To overcome this problem, this paper proposes a state-based safety analysis method for dynamic evaluation of the failure effect combining the situation factor. First, a hierarchical modeling framework that includes functional logic, physical architecture, and the failure mode is constructed, and then the cross-linking relationships between items are characterized by the state machines. Particularly, the event transmission mechanism and the global attribute updating mechanism are designed to realize the state synchronization of various systems, thus enabling the global propagation of failure. The feasibility of the proposed method is verified by simulations. The Enterprise Architect platform is used to model the aircraft integrated surveillance system and analyze the effects of different failure modes in typical situations. The proposed method complements the failure effect evaluation accuracy considering the dynamic interaction situations, thus realizing the global perception of the safety state, enhancing the dynamics and integrity of the failure effect analysis process.
PubDate: 2020-11-19
DOI: 10.1007/s42401-020-00073-8

• An analysis of global ionospheric disturbances and scintillations during
the strong magnetic storm in September 2017
• Abstract: Severe space weather events, e.g., solar flares and magnetic storm, can cause significant disturbances to the global ionosphere. The radio frequency signals, such as wireless communications and global satellite navigation system (GNSS) signals, often experience strong scintillations when traveling through the disturbed ionosphere layer. On 6 September 2017, the sun emitted the largest solar flare classified X9.3 since the 24th solar activity week. It triggered the geomagnetic storm and ionospheric storm on September 8, causing severe disturbances and scintillations of ionospheric. In this work, we take this event as the objective to investigate the characteristics of the ionosphere disturbance. First, the temporal and spatial distributions of ionospheric total electron content (TEC) are analyzed using the ground-based IGS data. The change of TEC is highly correlated with that of the geomagnetic indices and the magnetic storm has the greatest impact on low latitudes. Then, a five-point moving average method is adopted to extract the spatial fluctuations based on post-processed electron density and TEC data from COSMIC and GRACE missions. We find they show different disturbance characteristics in spatial distribution. In addition, the GNSS amplitude scintillation index S4 which is available from the COSMIC satellite mission is used to characterize ionospheric scintillation during this event. Weak scintillation occurred in most parts of the world on September 8 2017, while moderate scintillation is mainly concentrated around 120° W and 100° E. Our study can provide a basis for better evaluating the impact of ionosphere disturbance changes on satellite communication and navigation in space weather events.
PubDate: 2020-11-01
DOI: 10.1007/s42401-020-00067-6

• Aerial computing—security from missile threats and enhancing PUE
• Abstract: Data centers have operational challenges due to high cooling costs and the necessity of ensuring physical security to keep data safe. The activities of malicious organizations in countries without sophisticated missile defence systems also necessitate enhancing data center security. The expending of significant power for cooling degrades data center power usage effectiveness (PUE). The use of high altitude platform data centers (HAP-DCs) is proposed to address these challenges. The HAP-DC incorporates a location mechanism which ensures that HAP-DCs have a dynamic location making them difficult targets for aerial missiles. The paper also proposes a stratospheric scheduling mechanism to enhance the HAP-DC’s PUE. The scheduling mechanism ensures that HAP-DCs sited where the stratosphere has best cooling ability are used for workload execution. Analysis shows that the location mechanism enhances safety against missile threats by at least 6.7% and up to 35.4% on average. The scheduling mechanism enhances the PUE by at least 43.8% and up to 81.1% on average.
PubDate: 2020-10-19
DOI: 10.1007/s42401-020-00064-9

• Visual odometry errors and fault distinction for integrity monitoring
• Abstract: Visual odometry (VO) has been widely used for many purposes in the past decade. However, the three assumptions of VO are not often met in the reality, and therefore, the uncertainty of VO output (the pose of agent) should be estimated for safety’s sake, which can be done suitably by the integrity monitoring. To construct the integrity monitoring framework of VO, the first step is to establish the model of errors of measurements and calculate the fault rate, which has not been found in the literature to our knowledge. In response, this paper aims at establishing the model of errors of spatial points and calculating the fault rate in the stereo VO based on the feature point method. In this work, we describe the principle of stereo VO based on the feature point method in a deep and comprehensive way. The errors and faults of spatial points in stereo VO are defined, distinguished and classified in detail. The error propagation from pixel to spatial point is deduced, and the model of errors of spatial points is constructed. The KITTI odometry dataset is employed to evaluate the fault rate and standard deviation of errors of spatial points. And multiple sets of sensitive analyses are carried out to address the impact of RANdom SAmple Consensus (RANSAC) threshold, RANSAC iterations and operational scenario on spatial point error and fault rate. This paper could be a reference for constructing the integrity monitoring framework of stereo VO based on the feature point method.
PubDate: 2020-09-14
DOI: 10.1007/s42401-020-00062-x

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