Aiming at the problem of insufficient availability in the satellite receiver autonomous integrity monitoring (RAIM) method, an improved aircraft autonomous integrity monitoring (AAIM) method aided by barometric altimeter based on weight optimization is proposed under the actual configuration of the airborne navigation system. The information of satellite navigation system and barometric altimeter is

With the increased use of composite materials in aircraft structures, continuous and thorough monitoring of structural conditions is highly required for the assurance of safety and reliability. In this study, as part of the fiber Bragg grating (FBG) sensor-based aircraft health and usage monitoring system (HUMS) development research, in-flight strain monitoring of an aircraft tail boom structure using

The propellant supply system of a liquid rocket engine using an electric pump has high reliability because of the relatively small number of components. The system also has the merit of a quick response and ease of control owing to its simple configuration. Recently, the rocket lab developed the Rutherford engine, which has an electric pump cycle, because of the improved technology in the electric

In the aircraft operation, the metallic airframes are usually exposed to the extreme loading conditions during the flights due to which the risk of failure should be assessed and held to an allowed level to prevent the associated loss. If the components are inspectable, the components should be inspected routinely so that the fatigue damage can be detected before failure, which usually requires non-destructive

Recently, electrically driven pump-fed cycle rocket engines (i.e., ElecPump engines) have received considerable attention. ElecPump engines are superior to pressure-fed engines and will likely replace gas generator cycle engines under a 100 kN thrust level. This study focuses on LOX/methane ElecPump engines with a low-thrust level and estimates the nominal operation point of the engine. The objective

This paper proposes the engagement model and optimal task assignment algorithm for small-UAV swarm operations in hostile maritime environments. To alleviate the complexity of a real engagement environment, several assumptions are made: in the proposed engagement model, a vessel can attack the UAV within a certain range with a constant kill probability rate; and the ability of a vessel to attack UAVs

Among many composite material structures, honeycomb sandwich composites have been used in various ways. The honeycomb sandwich is adhered by polymer resin adhesive and the stiffness of honeycomb sandwich structures is determined by adhesive characteristics. This study is intended to evaluate adhesive characteristics after surface treatment and lateral compressive characteristics before and after thermal

Rotorcraft composite structures are required to satisfy desired reliability levels when analyzing the scatter of material properties at coupon and element levels in accordance with the Federal Aviation Regulations “FAR 29.573” and the Advisory Circular “AC 29.573”. By estimating the strength and life shape parameters from static and fatigue test results, load enhancement factors can be obtained. Thus

CubeSats are becoming increasingly popular in the scientific community. While they provide a whole new range of opportunities for space exploration, they also come with their own challenges. One of the main concerns is the negative impact which they can have in the space debris problem. Commonly lacking from attitude determination and propulsion capabilities, it has been difficult to provide CubeSats

This paper presents a study on airworthiness of fuel system for an unmanned air vehicle. The presented contents consist of network modeling for analysis and flight test results on fuel system airworthiness. First, performance prediction of fuel system for unmanned air vehicle was achieved using software tool based on theoretical analysis and empirical data. And also flight tests were performed for

In the present study, the interaction effect by inter-rotor spacing of coaxial rotor blades in hovering and forward flight is studied by using a Reynolds-averaged Navier–Stokes CFD flow solver based on mixed meshes. The meshes were composed of unstructured near-body region and Cartesian off-body region. The flux-difference splitting scheme of Roe was used for computing inviscid fluxes on the near-body

During service, a turbine engine undergoes frequently dynamic operations. Because of the changes in mass flow, temperature, pressure, as well as the different reaction of the components of turbine to these changes, the turbine performances may vary significantly. It is critical to understand and quantify these variations to design and integrate the turbine to the engine. This paper presents a study

In the present study, numerical simulation was conducted to study both the internal and external flows of a fluidic oscillator in a quiescent environment and with a crossflow. Unsteady Reynolds-averaged Navier–Stokes analysis was used to evaluate the flow field. The blowing ratio was varied to understand the interaction between the free stream and the oscillating jet. Results for the time-averaged

Detached Eddy Simulation is used to study the interaction flowfields of a supersonic lateral jet penetrating into the crossflow of projectiles with cruciform or X-type fin configurations at \({\text{Ma}} = 0.3\) and \(\alpha = 0^\circ ,30^\circ \sim 60^\circ\). For \(\alpha = 0^\circ\), typical flow structures such as barrel shock, Mach disk and counter-rotating vortex pair(CVP) induced from the jet

The tangential injection flow commingled with the mainstream could be abstracted as mixing layer, and profound importance is attached to aero-optical reduction for film-cooling target-seeking vehicles in engineering application. Leveraging the in-house code based on explicit fifth-order Weighted Compact Nonlinear Scheme and ray-tracing method, the supersonic mixing layer is numerically simulated to

In space exploration missions, the spacecraft have limited computing resources. In particular, the communications environments for these spacecraft, whether in deep space or the cislunar region, are characterized by intermittent connectivity loss, long signal-propagation delay, and high bit-error rates between spacecraft and their ground stations. Delay-Tolerant Network (DTN) has been introduced to

The effects of flow structure and particle size in the secondary combustor of a ducted rocket on mixing are investigated using a two-phase large eddy simulation analysis. The corner recirculation zone and central recirculation area appear in the combustor. Vortexes are generated mainly by the axial inlet flow. The stretched eddies along the axial direction appear on the rear section of the combustor

This paper proposes a new cooperative homing guidance to enhance the survivability of multiple anti-ship missiles against a high-value target such a frigate or a battleship when prior information on the target is unknown. In this paper, the survivability enhancement for the multiple anti-ship missiles against the battleship with no preliminary information on its current heading direction and weak spot

To ensure high-resolution image acquisition for a spaceborne parabolic synthetic aperture radar (SAR) antenna, an appropriate thermal design is important to minimize the thermal distortion of the antenna reflector in severe on-orbit thermal environments. This paper describes the results of a preliminary thermal design and the analysis of a carbon fiber reinforced plastic skin-based unfurlable parabolic

This study considers intermittent maneuver based on line-of-sight rate bounding to improve target observability for passive homing guidance. Target observability is critical for the performance of the target tracking filter and indirectly affects the guidance accuracy. This paper derives an observability measure associated with the Fisher information matrix for the adaptive intermittent maneuver strategy

This study conducts an aeromechanics analysis of a modern lift-offset coaxial rotor in high-speed flight. A lift-offset coaxial rotor of the Sikorsky X2 technology demonstrator (X2TD) is considered for the present study. For the analyses of rotor performance, blade airloads, and hub vibratory loads, a rotorcraft comprehensive analysis code, CAMRAD II, is used. For the rotor performance analysis at

Multi-DOF flexible space robots play a significant role in the on-orbit service. The flexibility of the robots is mainly caused by the flexible links and some flexible drive elements in joints. The vibration generated by the component flexibility can affect the accuracy of control. In this paper, the dynamics and control issues of flexible-link flexible-joint (FLFJ) space robots considering joint friction

To address standoff target tracking using a fixed-wing UAV in unknown background wind, a wind estimation based on Unscented Kalman Filter (UKF) is proposed. In the paper, UAV dynamic model and target state estimation are constructed, and Lyapunov vector field guidance (LVFG) framework is introduced to achieve standoff target tracking. The unknown target state and wind dynamic model have seldom been

In this paper, environmental tests were conducted with a MEMS (micro-electro mechanical system) oscillator, which is known to be robust under harsh environmental conditions, and comparisons with the existing TCXO (temperature-controlled crystal oscillator) were conducted. And the results of the environmental tests of a GNSS receiver equipped with the MEMS oscillator were compared with the test results

Target tracking using pseudo-measurement is widely used because of its simple implementation and computational advantages despite biased behavior. The biasedness of the pseudo-measurement tracking filter originates from a measurement-dependent Kalman gain and a state-dependent non-Gaussian biased noise. This paper proposes a bias-compensated pseudo-measurement filter considering a range rate measurement

Super-resolution reconstruction refers to the technique of reconstructing a high-resolution image from a single or a series of low-resolution images by digital image processing. This technology can not only increase the high-frequency information of the image, but also eliminate the low-resolution. Deep Learning has made breakthroughs in modern digital image processing. Compared to traditional algorithms

This paper intends to compare the effect of the attitude parameterization method on the performance of the attitude controller designed with the direct feedback of corresponding attitude states. To achieve this, the proportional-derivative controllers using the finite rotation angles and the modified Rodrigues parameters are designed with the same structure and equivalent performance of the direct

The flow field structure of a single injection port fluidic thrust vectoring nozzle was studied by introducing secondary flow injection in the expansion section of the two-dimensional convergent-divergent nozzle. To determine the motion characteristics of unsteady flow in a shock-induced fluidic vectoring nozzle, detached eddy simulation was conducted to simulate the three-dimensional flow field, and

The noise sources of the tip-jet driven rotor are mainly classified as rotor blade noise and jet noise. The rotor blade noise includes thickness noise, loading noise, and nonlinear quadrupole noise, while the jet noise includes nozzle momentum noise and jet radiation noise. Each noise component has different noise source mechanisms related to flow characteristics and the rotating motion. Especially

This paper proposes generalized polynomial guidance for controlling the terminal velocity vector (speed and flight path angle), which could be critical for the effectiveness of the warhead of tactical ballistic missiles. A polynomial reference trajectory satisfying the initial and terminal altitudes and flight path angles is introduced with a guidance parameter that can be chosen to change the terminal

This study proposes an algorithm to calculate fast the predicted intercept point (PIP) of the anti-ballistic missile system. A neural network system is trained to learn the motion of the ballistic target to predict the future target position. Then a prediction algorithm iteratively calculates PIP and the launch time of the interceptor. PIP calculation enables the missile to effectively approach to

An Improved Delayed Detached Eddy Simulation (IDDES) model as a kind of hybrid RANS/LES approach has been developed and applied to calculate tip leakage flow in a linear compressor cascade with moving casing, and the result was compared with the experimental results and LES results. The hybrid approach combines delayed detached eddy simulation (DDES) with an improved RANS–LES hybrid model aimed at

Propellant sloshing is one of the potential sources of disturbance which affects the stability and structural integrity of space vehicles. In this study, using a small scale model of the first Korean lunar orbiter fuel tank, which is partially filled with liquid fuel, the dynamic lateral sloshing has been simulated by CFD analysis for various fill-levels. Spherical tank geometry was assumed, because

An integrated guidance and control problem under state constraints is considered for terminal homing of missile engagement. The problem is formulated as a moderate-size convex optimization problem, which can be efficiently solved via existing techniques such as interior point methods or alternating direction method of multipliers. Two different formulations are presented, and their computation time

An air compressor has been adapted to a high-speed train to reduce the aerodynamic problems when passing through a tunnel. To evaluate the feasibility of the air compressor to attenuate the aerodynamic drag, pressure transient and the micro-pressure wave, the flow around the high-speed train has been simulated using the unsteady axisymmetric compressible Navier–Stokes equation. The simulation results

Position and time information provided by the satellite navigation system is important in many application fields. However, the satellite navigation signal is vulnerable to interference signals due to the low navigation signal strength. This interference signal for the satellite navigation signal is being advanced to the spoofing signal, which can adjust the position and time information of the satellite

This is a study on the loading spectrum for full-scale fatigue testing of composite aircraft structures. Fatigue tests are performed to confirm the durability and damage tolerance of a composite aircraft structure. In particular, as composite materials have fatigue life variance larger than that of metallic materials, it takes a considerable amount of time to complete the aforementioned tests. Investigation

This paper proposes a novel adaptive design of experiment (ADoE) framework with cost-aware sampling strategy and nonstationary surrogate model for efficient wind tunnel testing. The ADoE framework, which is based on the Gaussian process, can effectively reduce the required number of an experiment while maintaining its accuracy. The proposed cost-aware sampling strategy augments the framework by selecting

An inverse-simulation problem is reformulated to exactly satisfy the kinematic constraints imposed by the prescribed trajectory. Thereby, the problem can be transformed into an index 1 differential–algebraic equation that is much more easily solvable than the higher index system of the conventional formulation. Various numerical methods which have been successfully used in the pseudo-spectral inverse-simulation

To solve the problem of accurate control of air flow rate of a high-speed high-temperature heat-airflow test system, this paper introduces the working principle, establishes the mathematical model and analyzes the characteristics of the air supply subsystem. According to the characteristics of the air supply subsystem, such as time-varying parameters, time delay and disturbance, which are difficult

In this paper, a Global Navigation Satellite System (GNSS) antenna design which prevents low-noise amplifier (LNA) saturation (compression) and intermodulation caused by S-band signals is proposed to improve the reception of GNSS signals. A simulation was conducted to determine which method can more efficiently decrease the S-band signal while maintaining the noise figure and the antenna gain concurrently

Automatic Dependent Surveillance-Broadcast (ADS-B) is an air traffic surveillance system in which aircraft broadcast GPS position, velocity and status on 1090 MHz. Nowadays, as a valid alternative to SSR, ADS-B is the main technology for Air Traffic Management (ATM). With the rapid growth of airspace traffic and disappearance of MH370, satellite-based ADS-B is proposed to realize aerial surveillance

This paper explores the feasibility of a framework for vision-based obstacle avoidance techniques that can be applied to unmanned aerial vehicles, where such decision-making policies are trained upon supervision of actual human flight data. The neural networks are trained based on aggregated flight data from human experts, learning the implicit policy for visual obstacle avoidance by extracting the

Voluminous research exists on the effect of combination of low Reynolds number flow over low aspect ratio flat plate wings for usage in micro-aerial vehicles and UAVs, as they also fly under similar conditions and combination of low aspect ratio and low Reynolds number. It has been well established by many researchers (Torres and Mueller in AIAA 42(5):865–873, 2004; Okamoto and Azuma in AIAA 49(6):1135–1150

Satellites should have high reliability because they are required to operate autonomously, while performing a given mission. To realize this, it is necessary to use heritage parts or include redundancy. However, for nanosatellites, where it is difficult to include redundancy due to volume and weight limitations, fault management becomes crucial. In this study, a new method based on deep learning is

Aeroelasticity studies the interaction between the aerodynamic loads and the flexible structures, and has gained much attention in the design of modern aircraft. Most of the existing computational fluid dynamics/computational structural dynamics (CFD/CSD) coupling approaches are based on Runge–Kutta method, central difference method, linear multi-step method and so on, which are conditionally stable

The celestial navigation using the difference between the direct and reflected solar light is emerging, as the difference can remove the conjoint bias caused by the instability and unpredictability of sunlight. These navigation methods include the solar Doppler difference and the solar TDOA (time difference of arrival). The solar TDOA measurement has a high positioning accuracy. However, the solar

To suppress airfoil flutter, a lot of control methods have been proposed, such as classical control methods and optimal control methods. However, these methods did not consider the influence of actuator faults. We designed a new finite-time H∞ adaptive fault-tolerant flutter controller by radial basis function neural network technology and adaptive fault-tolerant control methods, taking into account

In this study, the effects of defects in a triaxial braided textile composite was studied at unit cell level using three-dimensional finite element analysis. The manufacturing defects such as void defect and tow misalignments were considered in the model and the effect of their presence at different scale on the effective material properties were studied. The configuration of the finite element model

This paper presents a numerical strategy for reliability-based design optimisation of an aircraft wing structure using a surrogate-assisted approach. The design problem is set to minimise aircraft wing mass subject to structural and aeroelastic constraints, while design variables are structural dimensions. The problem has uncertainties in the material properties. The Kriging model is used for estimating

The skin panel structures of vehicles in supersonic flights are subjected to combined thermal, acoustic, and aerodynamic loads. These combined loads may cause a nonlinear dynamic response of the high-speed flight vehicle’s panel structures. Among these nonlinear dynamic responses, the snapthrough and limit cycle oscillation response seriously affect the fatigue failure of the panel structures. This

The present work computationally investigated the combined effects of thermal non-equilibrium and chemical reactions on hypersonic air flows around an orbital reentry vehicle during its reentry. The chemically reacting gas flow around the orbital vehicle was simulated for actual reentry trajectories, with a computational solver based on the Navier–Stokes–Fourier equations. Hypersonic flows for a wide

This paper presents the effects of airflow bleed from the rotor shroud surface between leading and trailing edges on aerodynamic and structural performances of a single-stage transonic axial compressor, NASA stage 37, using three-dimensional Reynolds-averaged Navier–Stokes equations with the k–ε turbulence model. A small airflow mass flow rate is bleed throughout a rotor-bleeding ejector which designed

The current work analyzes the delta-V characteristics to deploy a lunar CubeSat impactor for an early phase feasibility study. The lunar CubeSat impactor is assumed to ride on the mothership and be deployed to hit the lunar surface during a flight inside the lunar sphere of influence (SOI). Different combinations of the periselene approach altitude and velocity for the mothership are considered to

Modern Earth-based radio antennas of very-long-baseline interferometry system are furnished with robust control systems for their pointing control. Their pointing accuracy is critical to the quality of the radio wave-front captured. External disturbances, particularly those of wind gusts, produce a non-negligible dynamic aeroelastic response that degrades its pointing accuracy, and yet are not mitigated

This paper investigates the flow characteristics and wind energy utilizations of H-type vertical axis wind turbine (VAWT) blade and its trailing-edge modification while having a certain camber to facilitate a greater understanding of the effects of airfoil’s trailing-edge thickness and relative camber. The geometric dimensions are designed for 100 W wind wheel with NACA0021 airfoil, whose trailing-edge

Wind turbine blades and aircrafts have grown in size to improve energy efficiency and reduce cost. The weight of these structures has also increased due to their larger sizes. Reducing the weight of these structures can increase efficiency and lower fuel consumption, and decrease the structural load. Fabricating structures using composite materials is currently the most popular way to reduce weight

In this paper, a new hybrid scheme which combines radial basic function (RBF) neural network with a model following sliding mode control technique to take their common features is used to solve attitude control problem of gliding guide projectile. The attitude kinematics model described by second-order nonlinear uncertain system is divided into two single-input single-output subsystems by considering

To improve the deployment stability and drive efficiency, the dimensional synthesis of antenna deployable support structure is addressed. First, to evaluate the deployment stability, the transmission ratio stability index (TRSI) is designed based on Jacobian matrix. Second, the motion/force transmissibility is used to analyse the drive efficiency. A sub-closed-loop analysis method (SAM) is proposed

In this paper, we address an automated gain tuning method using Asynchronous Advantage Actor-Critic (A3C) reinforcement learning approach. A quad-rotor Unmanned Aerial Vehicle (UAV) with nonlinear geometric tracking controller is introduced to test our approach. In the geometric controller, two attitude gains must be provided appropriately to achieve stable error dynamics. To ease the difficulties