The characteristics of unsteady boundary-layer transition on a small-amplitude pitching NACA0012 airfoil are investigated using the γ−Reθt¯−Ar transition model, which consists of the γ−Reθt¯ transition model and the roughness amplification factor (Ar) transport ...

To reveal the effects of random rib assemblage errors caused by misalignment on the performance of umbrella antennas, a novel computational method is proposed to evaluate the effects of random rib assemblage errors on surface accuracy, and is ...

This paper presents an adaptive fuzzy sliding mode controller (AFSMC) for the control of a nonlinear aeroelastic wing section. The proposed controller estimates both the model dynamics of the system and the switching control of the sliding mode. ...

Space robots are widely used for on-orbit capturing. After capturing a rotational non-cooperative target, its momentums produce unpredictable movements for the resultant space robot-target compound system. In order to address this problem, a ...

Fretting wear is a general surface damage form in tightly connected structures. Aimed at the curvic coupling of the disks in combined rotor gas turbine, using the finite-element method and Archard wear theory, the effects of the bolt preload, ...

The new generation high-strength steel sheet has been widely used to reduce the vehicle weight. In this study, the mechanical, metallurgical, and fatigue behavior of the resistance spot-welded joints of high strength steel sheets were ...

This paper presents a new, accurate, and fast methodology, remote sensing satellites coverage analysis (RSS-CA) for determining the coverage area of Earth observation satellites in concurrent design facilities (CDFs) devoted to space mission ...

The purpose of this work is to optimize systematically the maneuver required to identify the wind and calibrate the airspeed sensor of a subsonic aircraft using a global positioning system method. The optimization is based on sensitivity analyses ...

The present study investigates the efficacy of sinusoidal trailing-edge (TE) serrations as a passive means for the reductions of airfoil broadband noise, theoretically and experimentally. Comprehensive parametric studies were conducted to ...

An aircraft tire is a kind of rubber product with a complex structure. When subjected to impact load, the mechanical properties of rubber material on strain history and strain rate cannot be ignored. According to the previous impact compression ...

This paper investigated a nonlinear control algorithm for flight dynamics of aircraft using an integrator backstepping–based design. The paper focused on two points. Firstly, a systematic procedure was presented for formulating an integrator-...

Inlet separation is one of the primary sources of distortion at fan entrances. High angles of attack (AOAs) are the critical cause of inlet separation. Optimizing the inlet shape to increase the separation angle is of great engineering ...

A modular anti-unwinding dynamic scaling–based immersion and invariance (I&I) adaptive control is devised for rigid spacecraft attitude with inertia uncertainties. It is shown that the parametric regressor matrix cannot be integrable in the ...

Low-speed laminar flow over a slotted circular cylinder was numerically studied to investigate the slit effectiveness on the vortex shedding suppression and also determine the suppression mechanism physically. The base flow is two dimensional and ...

Unmanned aerial vehicle (UAV) path planning is an essential branch in UAVs research. This paper presents the hardware implementation of the UAV path planning problem using an improved parallel genetic algorithm (GA) in a multi-microcontroller ...

As research continues for the first crewed missions to and the eventual colonization of Mars, the need for materials for construction of structural and mechanical components remains paramount. The use of in situ resource utilization (ISRU) ...

Estimation of aeroelastic damping for a very flexible high-aspect-ratio wing using wind-tunnel test data is presented in this work through the comparison of four different methods: half-power, half-quadratic gain, an adapted version of random ...

A moving mass–actuated unmanned aerial vehicle (MAUAV) is controlled by mass sliders installed inside the airframe and has the advantages of high aerodynamic efficiency and good stealth performance. However, designing a controller for it faces ...

The development of nanosatellites is inseparable from micropropulsion systems, and a micropropulsion system cannot be separated from the evaluation of its micropropulsion performance. Although the ground measurement system is relatively mature, it ...

The path following a finless airship is presented in this paper using a nonunified sliding mode-based lateral guidance and control framework. The outer-guidance loop relies on the airship’s kinematics, and the designed sliding surface is based on ...

Because shock absorbers are an important component of high-rise buildings, it is essential to be able to detect damage to them. Viscoelastic (VE) dampers, as a common shock absorber, directly affect the safety and reliability of VE materials over ...

Onboard computation of a fuel-optimal steering law is a pivotal technology for future lunar and planetary campaigns with pinpoint landings. This paper proposes a method of downrange estimation based on improved powered explicit guidance (PEG) ...

A rocket-based combined-cycle (RBCC) inlet is always required to start at a relatively low Mach number in consideration of the fuel consumption in the ejector mode and the comprehensive engine performance throughout the flight trajectory. However, ...

For aerodynamic shape design using gradient-free searching algorithms, which can be applied more flexibly than gradient-based ones, computing costs increase dramatically with dimensionality. Rational design variables are considered vital to ...

Bending fatigue, as one of the impact factors to reduce a metal’s service life, could play a critical role in fatigue life estimation of aerospace components and civil infrastructures, such as in machine gears, splined shafts, and wind-turbine ...

Air-data, recorded in the flight data of civil aviation aircraft, can be disturbed by wind disturbance, thus leading to measurement error. A two-stage air-data estimation in wind disturbance was studied to obtain accurate true airspeed, angle of ...

Flat-ended projectiles were used to impact three distinct thicknesses of 2024-T351 plate. Ballistic limit velocities were determined, and optical microscopic examination revealed evidence of adiabatic shear bands within the impacted plates, which ...

This paper investigates the robust continuous fractional-order nonlinear sliding mode (RCFONSM) control scheme for controlling a disturbed uncertain quadrotor (DUQ). First, the fractional-order nonsingular terminal sliding mode (FONTSM) manifolds ...

The compliance of the mixed-mode bending (MMB) test fixtures can influence the interlaminar fracture toughness measurements for different mixed-mode ratios in an unpredictable way. The purpose of this article is to introduce the improved mixed-...

Oxygen-consuming fuel tank inerting technology is a novel technology with a simple structure and a high efficiency for tank explosion suppression based on flameless catalytic combustion. To verify the feasibility of the oxygen-consuming inerting ...

With the development of hypersonic vehicles, considerable attention has been paid to thermal protection systems (TPSs). Among the different types of TPS, integrated TPS (ITPS) has attracted extensive interest because of its light weight, cost ...

The paper considers practical aspects of mathematical modeling in predictions of the level of near-field pressure pulsations of a near-future prototype supersonic business aircraft. A numerical modeling technique based on the numerical solution of ...

Computational fluid dynamics is applied to reproduce the characteristics of the liquid methanol burner presented by the National Institute of Standards and Technology (NIST). Reynolds average Navier-Stokes (RANS) and large-eddy simulations (LES) ...

A new design method of scramjet nozzles within predetermined geometrical space is proposed to optimize the nozzle aerodynamic performance. The main characteristic of the proposed method is that the design factors and flow angle are employed to ...

This paper investigates the dynamical behaviors of Earth frozen orbits including the critical inclination orbit in the zonal problem with terms of perturbations up to J15. From the mean element theory, an analytical expansion of the dynamics model is ...

The closed-loop performance of an inertial stable platform (ISP) affects the operation of navigation in moving objects. In this paper, the issue of high-performance control of ISP is discussed. By proposing a novel backstepping controller, the ISP ...

In this paper, computational fluid dynamics (CFD) numerical simulation and wind tunnel tests are used to study the wind environment of typical buildings in coastal cities. Firstly, the geometric three-dimensional model is established, and the ...

In this study, overlapped biaxial and seamless twill carbon fiber pipes and vessels were manufactured. Steel pressure vessels were repaired with flexible twill and biaxial fabric. The pipes and vessels were subjected to hydrostatic pressure, ...

In situ resource utilization (ISRU) of lunar regolith is indispensable for the success of large-scale and long-term human lunar explosions at lower costs. Many new technologies must be developed to realize efficient ISRU. Because particle sorting ...

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Honeycomb-core sandwich structures are commonly utilized as orbital debris shielding in unmanned satellites. This study investigated the effects of projectile shape on the ballistic performance of aluminum honeycomb-core sandwich panels subjected ...

In this paper, a passive fault tolerant attitude control is investigated for a nano-satellite with three magnetorquers and one reaction wheel in the presence of actuator constraints, external disturbances, and partial loss of actuator ...

Reducing rotor blade–vortex interaction (BVI) noise is a major challenge in rotorcraft research. This paper presents a high-resolution numerical study of the effects of blade surface blowing on BVI noise reduction. Using the improved fifth-order ...

Blade-vortex interaction (BVI) noise is a significant source of rotor noise. In recent years, active flap control (AFC) has been used successfully to control BVI by adding a trailing edge flap to the blade. However, due to the rotor’s complex ...

Large deformation analyses of structures are of great importance to the evaluation of structural performance under extreme environmental loads, but currently available methods are time-consuming because of the requirement of factorizing large-...

It is seemingly inevitable that one day humans will land on the surface of Mars. Between the Apollo lunar missions, International Space Station, and Martian rovers and landers, much of the technology required to transport astronauts to Mars ...

The complexity of the kinematics and aerodynamics of rotors is a challenging problem for achieving accurate modeling for prediction of rotor loads. The present paper describes an unsteady aerodynamic model based on strip theory for the prediction ...

This paper addresses the maintenance of a halo orbit around the L1 point of the Sun-Earth system in a circular restricted three-body problem. To this effect, a trajectory tracking problem is formulated and solved by designing various controllers ...

The purpose of this study was to investigate the energy-harvesting performance of a piezoelectric free-flying aircraft model under discrete gust. A fluid-structure-electric coupled simulation framework was established by loose coupling the ...

This paper proposes a robust adaptive predefined-time control scheme for spacecraft rendezvous maneuvers with the consideration of input saturation and external disturbances. To ensure the rendezvous maneuver completing within a predefined time, a ...

An active attitude control system using a novel six-layer electromagnetic embedded printed magnetorquer for a 3-U nanosatellite is presented in this paper. The proposed design was optimized in terms of size, dissipated power, torque produced, and ...

In this paper, the problem of spacecraft formation attitude control in the presence of state constraints has been investigated. Multiple constraints such as a spacecraft’s forbidden-attitude avoidance and also the maximum allowable spacecraft ...

Lighthill’s aeroacoustic analogy connects acoustic source terms with vortical and turbulent structures. For resolving vortical and turbulent structures in computational fluid dynamics (CFD) simulations, mesh refinements in certain regions of the ...

The optimization of piezoelectric actuator placement has been widely investigated in connection with active vibration control. In this paper, a modified optimization criterion considering the control spillover effect is proposed based on modal ...

To understand the response of polymeric materials used in fiber-reinforced composite structures, it is necessary to examine their brittle failure mechanisms under various loading scenarios. As such, this study presents the quasi-static and dynamic ...

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How to conveniently tune the flexibility of the composite anisotropic flapping wing to an optimum level to improve flight efficiency is still an open question. Two simple methods have been put forward to realize the quick adjustment of flexibility ...

The aerodynamic performance of aircraft can be improved via shape morphing of wings actuated by piezoelectric material. An integrated design approach of piezo-actuated wings was developed while simultaneously considering aeroelastic tailoring of ...