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Quarterly published in print and online "Inventi Impact: Aerospace Engineering" publishes high quality unpublished as well as high impact pre-published research and reviews catering to the needs of researchers and professionals. It focuses on multidimensional aspects of aerospace engineering, particularly - aerodynamics, computational fluid dynamics, wind tunnel testing of buildings and structures, aerospace structures and materials, dynamics and control, real-time data acquisition, space engineering and construction, lunar base construction, field and remote sensing, robotics, etc
Space assistant robots can help astronauts or their assistants perform certain tasks. A ground microgravity simulation
environment is built for the space assistant robot AAR-2. The hardware requirements of the ground simulation by the 3-DOF
microgravity air flotation platform. An algorithm is designed for this simulation system. By using momentum and RMSprop
methods to improve the PID neural network, the challenging problem of strong coupling between system nonlinearity and
variables is solved. Firstly, the paper introduces the hardware system and deduces the dynamic model of the system. Then, the
algorithm is calculated and simulated. Through simulation, the effectiveness and feasibility of the algorithm are compared and
proved. Finally, the control system is simulated by MATLAB/Simulink and compared with other advanced algorithms. The
simulation results show that the designed neural network controller can quickly and accurately control the 3-DOF of freedom
motion of AAR-2....
Boundary layer transition is a hot research topic in fluid mechanics and aerospace engineering. In low-speed flows, twodimensional\nTollmien-Schlichting (T-S) waves always dominate the flow instability, which has been modeled by Coder and\nMaughmer from 2013. However, in supersonic flows, three-dimensional oblique Tollmien-Schlichting waves become\ndominant in flow instability. Inspired by Coder and Maughmerâ??s NTS amplification factor transport equation for twodimensional\nTollmien-Schlichting waves in low-speed flows and Kroo and Sturdzaâ??s linear stability theory (LST) analysis\nresults for oblique Tollmien-Schlichting waves in supersonic flows, a new amplification factor transport equation for oblique\nTollmien-Schlichting waves has been developed based on LST. The compressible Falkner-Skan similarity equations are\nintroduced to build the relationships between nonlocal variables and local variables so that all the variables used in the\npresent model can be calculated using local variables. Applications of this new transport equation to the flows over\nsupersonic flat plate, 3% thick biconvex airfoil, and one modified supersonic laminar airfoil show promising results compared\nwith the standard LST analysis results....
As technology continues to leap forward and innovations advance, the systems of civil
aircraft are becoming increasingly sophisticated and complex. Accordingly, there is a rising amount
of information to be processed by pilots in the cockpit, increasing their cognitive burden, which
significantly threatens the safety of flight. Thus, designers have formulated cockpit layout principles
relating to importance, frequency of use, functional grouping, and operation sequence on the basis of
ergonomics, which can effectively reduce the cognitive burden for pilots. The degree to which the
cockpit layout of a model conforms to the four design principles can indicate its ergonomic design
level. In accordance with the concepts of the above four cockpit layout principles, evaluation methods
for determining their respective conformity to the four design principles were proposed in this paper.
These methods use the operational sequence of cockpit system controls used in the normal flight
mission of the actual aircraft type as the evaluation data source. Subsequently, the total evaluation
results for cockpit layout were obtained using the weighted accumulation method. Lastly, the process
for evaluating the cockpit layouts of civil aircraft was illustrated using the cockpits of the A320 series
and B737NG series as examples. Based on the final evaluation results, the feasibility and effectiveness
of the proposed evaluation method was verified....
Recognizing isolated digits of the flight callsign is an important and challenging task for
automatic speech recognition (ASR) in air traffic control (ATC). Fortunately, the flight callsign is a
kind of prior ATC knowledge and is available from dynamic contextual information. In this work,
we attempt to utilize this prior knowledge to improve the performance of the callsign identification
by integrating it into the language model (LM). The proposed approach is named context-aware
language model (CALM), which can be applied for both the ASR decoding and rescoring phase.
The proposed model is implemented with an encoder–decoder architecture, in which an extra
context encoder is proposed to consider the contextual information. A shared embedding layer is
designed to capture the correlations between the ASR text and contextual information. The context
attention is introduced to learn discriminative representations to support the decoder module. Finally,
the proposed approach is validated with an end-to-end ASR model on a multilingual real-world
corpus (ATCSpeech). Experimental results demonstrate that the proposed CALM outperforms other
baselines for both the ASR and callsign identification task, and can be practically migrated to a
This paper presents a trajectory optimization algorithm for super-synchronous-transfer-orbit (SSTO) large launch systems by
convex optimization. The payload of SSTO launch systems is typically a geostationary equatorial orbit (GEO) satellite, and the
time and position of orbital injection are constrained, which is quite different from the case of general satellites. In this paper,
the optimal control problem of SSTO large launch systems is formulated considering the terminal constraints including orbital
elements and the time-position equation. To improve the computational performance of the algorithm, the terminal orbital
element constraints are expressed in the perifocal coordinate system with second-order equations. And then, several
convexification techniques and their modified strategies are applied to transform the original trajectory optimization problem
into a series of convex optimization problems, which can be solved iteratively with high accuracy and computational efficiency.
Considering the time-position constraint of the payload, the flight time updater design method is proposed to correct the error
of time during the flight, which lays solid foundation for the subsequent flight phase, guaranteeing that the GEO satellite
settles into the required position. Finally, simulation results indicate the high efficiency and accuracy and strong robustness of
the proposed algorithm in different special situations including engine failure and time delay. The algorithm proposed in this
paper has great development potential and application prospect in onboard trajectory optimization of SSTO launch missions
and similar situations....
This paper describes a detached-eddy simulation (DES) for the flow over a wall-mounted hump. The Reynolds number based\r\non the hump chord is Rec = 9.36 Ã?â?? 105 with an in-let Mach number of 0.1. Solutions of the three-dimensional Reynoldsaveraged\r\nNavier-Stokes (RANS) procedure are obtained using the Wilcox k - ? equations. The DES results are obtained using\r\nthe model presented by Bush and Mani and are compared with RANS solutions and experimental data from NASAÃ¢â?¬â?¢s 2004\r\nComputational Fluid Dynamics Validation on Synthetic Jets and Turbulent Separation Control Workshop. The DES procedure\r\nexhibited a three-dimensional flow structure in the wake, with a 13.65% shorter mean separation region compared to RANS and a\r\nmean reattachment length that is in good agreement with experimental measurements. DES predictions of the pressure coefficient\r\nin the separation region also exhibit good agreement with experiment and are more accurate than RANS predictions....
The author reviews the state of art of nonrocket launch assistance systems (LASs) for spaceflight focusing on air launch options.\r\nThe author proposes an alternative technologically feasible LAS based on a combination of approaches: air launch, high-altitude\r\nballoon, and tethered LAS. Proposed LAS can be implemented with the existing off-the-shelf hardware delivering 7 kg to low-earth\r\norbit for the 5200 USD per kg. Proposed design can deliver larger reduction in price and larger orbital payloads with the future\r\nadvances in the aerostats, ropes, electrical motors, and terrestrial power networks....
Piezoelectric transducers have a long history of applications in nondestructive evaluation of material and structure integrity owing\r\nto their ability of transformingmechanical energy to electrical energy and vice versa. As condition basedmaintenance has emerged\r\nas a valuable approach to enhancing continued aircraft airworthiness while reducing the life cycle cost, its enabling structural\r\nhealth monitoring (SHM) technologies capable of providing on-demand diagnosis of the structure without interrupting the aircraft\r\noperation are attracting increasing R&D efforts. Piezoelectric transducers play an essential role in these endeavors. This paper is\r\nset forth to review a variety of ingenious ways in which piezoelectric transducers are used in todayÃ¢â?¬â?¢s SHM technologies as a means\r\nof generation and/or detection of diagnostic acoustic waves....
This paper presents the development of a low cost miniature navigation system for autonomous flying rotary-wing unmanned\naerial vehicles (UAVs). The system incorporates measurements from a low cost single point GPS and a triaxial solid state\ninertial/magnetic sensor unit. The navigation algorithm is composed of three modules running on a micro controller: the sensor\ncalibration module, the attitude estimator, and the velocity and position estimator. The sensor calibration module relies on a\nrecursive least square based ellipsoid hypothesis calibration algorithm to estimate biases and scale factors of accelerometers and\nmagnetometers without any additional calibration equipment. The attitude estimator is a low computational linear attitude fusion\nalgorithm that effectively incorporates high frequency components of gyros and low frequency components of accelerometers and\nmagnetometers to guarantee both accuracy and bandwidth of attitude estimation. The velocity and position estimator uses two\ncascaded complementary filters which fuse translational acceleration, GPS velocity, and position to improve the bandwidth of\nvelocity and position. The designed navigation system is feasible for miniature UAVs due to its low cost, simplicity, miniaturization,\nand guaranteed estimation errors. Both ground tests and autonomous flight tests of miniature unmanned helicopter and quadrotor\nhave shown the effectiveness of the proposed system, demonstrating its promise in UAV systems....
A guidance problem for impact time and angle control applicable to cooperative attack is considered based on the sliding mode\ncontrol. In order to satisfy the impact angle constraint, a line-of-sight rate polynomial function is introduced with four tuning\nparameters. And the time-to-go derivative with respect to a downrange orientation is derived to minimize the impact time error.\nThen the slidingmode control surface with impact time and angle constraints is constructed using nonlinear engagement dynamics\nto provide an accurate solution. The proposed guidance law is easily extended to a nonmaneuvering target using the predicted\ninterception point. Numerical simulations are performed to verify the effectiveness of the proposed guidance law for different\nengagement scenarios....
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