Evacuation zone recommendations are determined for potential asteroid impacts. In most impacts on land, the dominant damage mechanism is the blast wave. Hurricane evacuations in the United States show that on average people evacuate to a 1 in a million risk of fatality level. To achieve the equivalent risk from a blast wave, preliminary estimates show that everyone within the 1–2 psi (≈0.07–0.14?atm

Human desire to explore Mars has persisted throughout history, and especially, it is required to achieve precise and safe landings on the Martian surface. The atmospheric entry phase plays a crucial role in ensuring mission success, and active research on entry guidance methods continues. This paper presents a comparative study between the two primary types of entry guidance methods: (1) path planning-tracking

The non-equilibrium spectra of shock-heated nitrogen in the UV-visible range are investigated in a detonation driven shock tube. Spectral identification indicates that the main contributors to the spectra are molecular radiation of N2(2+) and N2+(1-). Vibrational and rotational temperatures of N2(C) and N2+(B) are determined through spectral fitting. The post-shock spectra of pure nitrogen are obtained

Complex shock interactions on the lips of hypersonic vehicles typically induce severe aerodynamic thermal loads. Considering a V-shaped blunt leading edge as the simplified model of the lip, the design, optimization, and performance of secondary recirculation jets for reducing aerodynamic thermal loads are investigated. The secondary recirculation jet scheme is crucial in reshaping the shock interaction

The boundary layer ingesting (BLI) fan is continuously working under distorted inflows. The rotor blade moves across the distorted and undistorted regions and the resultant off-design condition makes the loss present a notable non-uniform distribution feature. Accurately capturing the loss is very important for evaluations of BLI fan performances in preliminary design stage. However, unsteady Reynolds-Averaged

Origami and kirigami folding methods applied to deployable structures have been investigated in many studies, and most of them use approximately zero-thickness materials to follow the paper-folding movement. However, the rigidity and thickness of materials cannot be neglected in aerospace engineering applications, resulting in different kinematic and dynamic characteristics of deployment. This work

Considering changes in the structural size and mass caused by the on-orbit assembly process in a planar space solar power satellite, this study proposes an improved robust recursive algorithm to identify the time-varying inertia tensor parameters of the system. In this algorithm, to decrease the effect of impulsive disturbance on inertial parameter identification during the on-orbit assembly and improve

Journal of Guidance, Control, and Dynamics, Ahead of Print.

Journal of Guidance, Control, and Dynamics, Ahead of Print.

Journal of Guidance, Control, and Dynamics, Ahead of Print.

Journal of Guidance, Control, and Dynamics, Ahead of Print.

The Fermi paradox and the Drake equation seem to be incompatible. Here we shall show that is not so, and the paradox actually justifies the assumptions made in formulating this equation.

The combustion chamber baffle is an important means to suppress the combustion instability of the combustion chamber of liquid rocket engine. In order to study the influence of spray impacting on the baffle on the atomization characteristics of injector, sufficient experimental research has been carried out in this paper. In the present study, the effects of different gas/liquid flow rates and different

Autonomous spacecraft relative navigation via monocular images became a hot topic in the past few years and, recently, received a further push thanks to the constantly growing field of artificial neural networks and the publication of several spaceborne image datasets. Despite the proliferation of spacecraft relative-state initialization algorithms developed, most architectures adopt computationally

Space-age technology makes it possible to travel faster than the speed of sound from one continent to another one or even to make suborbital flight as a space tourism. The existing technology challenge is to bring this innovative way of travel without damaging the environment to ensure human safety and to preserve environment balance. The sonic boom issue is one of the concerns when flying faster than

An electric pump-fed cycle can enable the electrical control of pump revolutions and rapidly vary the propellant flow rate. This paper proposes the pump control method as a flow control system of an electric pump-fed cycle. In order to evaluate the applicability of the designed flow control system, the test equipment that simulates an electric pump-fed cycle was constructed, including the Li-ion battery

The complex flow of a supersonic jet (Mach number 2.4–2.5) around the blunt aerodynamic body (consisting of a cylinder with a diameter of 16?mm and a truncated cone) was studied using the high-speed shadowgraph technique and computer vision-based visual data processing. The problem considered is directly related to the rocket and space systems stages safe separation problem in a sufficiently dense

This paper presents the high-fidelity physical modeling of a Thrust Vector Control (TVC) system operated by Electro-Mechanical Actuators (EMAs) for Reusable Launch Vehicles (RLVs). In contrast to simplified, often linear, models, high-fidelity physical models enable a better assessment of the actual system performance and a deeper verification of the on-board software robustness against disturbances

Abstract not available

Beamforming techniques cannot effectively separate the mixed field of stationary and rotating sound sources. The issue becomes even more challenging when strong out-of-focus sources, e.g., stationary sources with rotating beamforming, are present, leading to a smearing effect and false localization results. The current algorithms for separating multiple moving sound sources have problems such as weak

We propose a novel surrogate modelling approach to efficiently and accurately approximate the response of complex dynamical systems driven by time-varying exogenous excitations over extended time periods. Our approach, namely manifold nonlinear autoregressive modelling with exogenous input (mNARX), involves constructing a problem-specific exogenous input manifold that is optimal for constructing autoregressive

Over the last few decades, multirotor UAVs have become significantly popular because of their various applications. However, multirotors suffer from poor endurance performance as compared to other aircraft configurations with lifting surfaces. This limitation can be addressed by improving the technology of components or by developing design optimization approaches at the vehicle level. This paper presents

Accurate trajectory tracking is essential for the success of space robotic missions. However, challenges such as modeling uncertainty, measurement noise, and excessive sampling interval can degrade tracking performance and then deteriorate the control safety. In this study, a robust adaptive approach for trajectory tracking of space robotic manipulators is proposed to address the above challenges.

This work examines the active control of vehicle buffeting noise using a dielectric barrier discharge plasma actuator (DBD-PA). First, the buffeting noise characteristics of a cavity under different inflow wind speeds are established through a wind tunnel test, and the effectiveness of the buffeting noise measurement results is verified. Various types of actuator layouts are designed based on specific

This paper presents an improved process for the modeling, model order reduction (MOR), and control design of a flexible flying wing unmanned aerial vehicle based on the linear parameter-varying (LPV) technology. By applying the Lagrangian formulation and doublet lattice method, the aeroservoelastic (ASE) model of the flexible aircraft is first derived and then rewritten as an airspeed-dependent LPV

With distributed propulsion and electric vertical take-off and landing aircraft on the rise, fast and accurate methods to simulate propeller slipstreams and their interaction with aircraft components are needed. In this work, we compare results obtained with a filament-based free wake panel method to experimental and previously validated numerical data. In particular, we study a propeller-wing configuration

Frequency locking phenomenon induced by modal coupling can effectively overcome the dependence of peak frequency on driving strength in nonlinear resonant systems and improve the stability of peak frequency, which has a fundamental role in improving the dynamic performance of resonant devices. Most research has been focused on a single mechanical frequency locking, but less research has been done on

Most fault identification methods based on deep learning rely on a large amount of data, and their effects are limited in the actual production environment. In the case of multiple classification, limited data and complex working conditions, the bearing fault identification is very difficult. In this paper, a novel method called ensemble transformer meta-learning (ETML) is proposed for bearing fault

Green function is the important component for ultrasonic time reversal based super resolution imaging methods. Time reversal with multiple signal classification (TR-MUSIC) and its phase-coherent form (PC-MUSIC) are two typical imaging methods. In this paper, the effect of Green function on the TR-MUSIC and PC-MUSIC has been investigated. And TFM has also been introduced as a comparison. Point spread

Human exploratory missions to Moon or Mars are considered the next steps in human space exploration. Such activities result in the exposure of humans to the space environment for long time, especially under the constraints of orbital dynamics as with increasing distances from earth quick return possibilities are ruled out. Crews on these kinds of missions must be self-sustaining in medical treatments

Insight into supersonic combustion characteristics of thermally cracked fuels in a scramjet combustor is crucial for the development of next-generation supersonic flight vehicles. In the present study, four typical thermally cracked fuels at pyrolysis temperatures of 450, 550, 600, and 650 ℃ (denoted as ckori, ck550, ck600, and ck650) were selected. Improved delayed detached eddy simulation (IDDES)

The parasitic motion of microgripper jaws affect clamping accuracy. The parallelogram mechanism (PM) is often used as the last-stage of the multi-stage amplification mechanisms (AMs) because of its parallel clamping characteristics. However, the PM traditionally used in multi-stage AMs is asymmetrically stressed, which will affect its parallel clamping accuracy. Based on this, a PM with symmetrical

Effective bridge structural health monitoring systems offer a route to assist in the safe and economic operation of bridges, but have seen limited adoption onto the short and medium-span bridges which represent the majority of our bridge stock. This lack of adoption is in part due to the practical challenges of deploying bridge SHM systems in resource-constrained environments, especially where long-term

Latching control is a phase optimization control mechanism for improving the energy conversion efficiency of a wave energy converter (WEC). This paper, for the first time, extends the latching mechanism to vibration control to improve energy dissipation efficiency. An innovative semi-active latched mass damper (LMD) is proposed in this paper by integrating conventional tuned mass dampers (TMD) and

The forward computational modal analysis (CMA) of the motor stator assembly is gaining attention as a technical challenge in the area of motor noise. There is still no effective method to obtain accurate anisotropic material parameters (AMPs) required for CMA without prototype motors. In this paper, a novel forward calculation method (FCM) for calculating AMPs of the motor stator assembly is proposed

Elastic metasurfaces have shown remarkable ability in exotic wavefront manipulations based on the generalized Snell’s law (GSL), stimulating great promise for many potential applications, such as elastic wave signal processing, vibration control, and energy harvesting. However, elastic metasurfaces suffer from strong narrow-band confinement and dispersion modulation due to the inherent velocity-dispersive

A blade disk system plays a crucial role in the energy conversion efficiency of turbomachinery. Generally, a bladed disk is designed as a tuned system, which implies that the dynamic behaviors of all the blades are identical. In practice, there are some differences between the blades, known as mistuning, that can result in localized vibration. Thus, in this study, an approximate symplectic method developed

Considering the calculation efficiency and accuracy of meshing characteristics of gear pair with tooth root crack fault, the parametric model of cracked spur gear is established by simplifying the crack propagation path. LTCA method is used to calculate the time-varying meshing stiffness (TVMS) and transmission error (TE) of the cracked gear pair, and is verified by finite element (FE) method. The

We present an active control method for achieving non-collocated vibration absorption, implemented on a lumped mass system. The task of suppressing vibrations at a number of frequencies, at a target mass is recast into a problem of assigning zeros of the transfer function from the external excitation force to the position of the target mass. The controller design involves computing the controller parameters

The Mars rotorcraft is an aerial exploration platform capable of repeated take-offs and landings to extend the range of rover explorations. NASA’s Ingenuity helicopter is a full y functioning coaxial helicopter for technology demonstration. Increasing the rotor diameter or the number of blades can enhance the load capacity of the coaxial helicopter but would make it difficult to be folded. A more suitable

Air-breathing electric propulsion (ABEP) refers to a spacecraft in very-low Earth orbit (VLEO) harnessing upper atmospheric air as propellant for an electric thruster. This allows the orbital altitude to be maintained via drag-compensation, removing the need for on-board propellant storage and allowing a mission lifetime which is not limited by propellant capacity. A cathode (or neutraliser) is required

Numerical simulation and analysis are carried out on interactions between a 2D/3D conical shock wave and an axisymmetric boundary layer with reference to the experiment by Kussoy et al. [AIAA J, 1980, 18(12): 1477–1487], in which the shock was generated by a 15° half-angle cone in a tube at 15° angle of attack (AOA). Based on the Reynolds-averaged Navier–Stokes equations and Menter's SST turbulence

This research discusses the attitude tracking issue for hypersonic morphing vehicles (HMVs) subject to multisource uncertainty and limited system resources. Hypersonic vehicles with variable-span wings can change the aerodynamic configuration according to various requirement segments. However, A morphing process will cause significant changes in aerodynamic coefficients, mass distribution, and inertial

New aircraft concepts are currently being developed with the goal of less emissions of CO2 and noise. Remarkable noise reductions in long-range aircraft can only be expected from disruptive vehicle designs, new propulsion systems and specific low-noise technologies. In this paper, one such future vehicle design, a blended wing body (BWB) long-range aircraft, is described and studied with respect to

Turboprop aircraft plays an important role in the field of regional airliners and military transport. During take-off or landing, turboprop aircrafts frequently encounter bird flocks that can be ingested into the engine inlet, thereby posing a significant threat to flight safety. Consequently, the aerodynamic characteristics and bird ingestion characteristics of turboprop inlet are investigated in

Flow and aerothermal characteristics of rarefied hypersonic flows passing through slender cavities are investigated comprehensively using the direct simulation Monte Carlo (DSMC) method by various cases, such as the cavity with different depth-to-width ratios and different inclination angles, and the freestream at different altitudes and Mach numbers. The cavity depth-to-width ratio has a great influence

Condition monitoring of helicopter transmission system is the main focus of Health and Usage Monitoring System. Existing anomaly detection methods for transmission system ignore the challenges caused by variable flight regimes of helicopter, which greatly hinders their application in application scenarios. For the first time, we propose Decoupling Variational AutoEncoder (DVAE) as a pioneering solution

Considering the actuator faults that occur during the automatic landing of carrier-based aircraft, a novel automatic landing method based on a collaboration of fault reconstruction and fault-tolerant control is proposed. The variables of the aircraft states and actuator fault are combined as a new state, and an extended state observer (ESO) is constructed to establish the deviation-based observation

Path planning is one of the key technologies in unmanned aerial systems. The path-planning algorithm for UAVs in this study incorporates a three-dimensional obstacle model, addressing the limitations of existing research that primarily focuses on the two-dimensional plane. This approach elevates traditional two-dimensional obstacle constraints to a three-dimensional space, fulfilling the requirements

Mixed-flow pump is an important machine for transporting fluids, which has the advantages of both centrifugal pump and axial flow pump, but it is prone to cavitation, endangering efficiency and safe operation. A 20?m?×?8.5?m high-precision hydraulic mechanical stand and a vertical mixed-flow pumping station device were built for the study of cavitation signals. The detection of pressure pulsation signal

Health indicators (HI) are crucial in early fault alarm and degradation monitoring of mechanical failures. In recent years, many HIs are developed and reported, however, a constructed HI which is more sensitive to incipient defect, robust to varying operating conditions and is interpretable to characterize the degradation process is still remain to be studied. To address this issue, a more powerful

The ship lock system of the Three Gorges Hub(TGH) stands out as the most intricate navigation system for ships passing through dams, which is composed of the the world’s largest ship lock and ship lift. It operates with features like multi-dam configurations, multi-chambers, multi-operation modes and batch processing. This paper addresses the complex challenge of optimizing the lock schedule, ship

One of the most important technological challenges in the railway context nowadays is reducing the noise produced by the interaction between the train wheels and the track surface, that is the rolling noise. Introducing viscoelastic damping in the railway structure is one method to mitigate this rolling noise. In the paper, we investigate the impact of damping in the vibrational response of railway

In the past, space trajectory optimisation was limited to the design of space transfers to single destinations. More recent mission concepts however present the challenge to target multiple destinations; be it for science, exploration or even exploitation. This paper focuses on space trajectories that aim to visit multiple main-belt asteroids with one single spacecraft. The trajectory design of these

Leveraging advancements in micro-scale technology, we propose a fleet of autonomous, low-cost, small solar sails for interplanetary exploration. The Berkeley Low-cost Interplanetary Solar Sail (BLISS) project aims to utilize small-scale technologies to create a fleet of tiny interplanetary spacecraft for rapid, low-cost exploration of the inner solar system. This paper describes the hardware required

Balloon-based exploratory platforms, or aerobots, are a budding planetary exploration technology for Venus to collect scientific data in-situ while keeping a safe distance from the highly inhospitable surface of Earth’s “evil twin”. Such a mission is expected to deploy and inflate the aerobot during the system’s initial descent through the Venusian atmosphere, rather than launched from the surface

The Hyper Velocity Impact Experiments of prospective structural materials and shields are necessary to ensure the safety of satellites and spacecraft, particularly in lower earth orbits. The advancement of computational tools has made it simpler to reproduce the hyper velocity impact scenarios by facilitating the change in control parameters during simulations. Numerical models have been extensively

Due to the limited onboard computational capacity, offline landmark sequence selection is widely considered to be beneficial to improve the observability, and thus estimation accuracy of asteroid landing visual navigation. Because of the inevitable pose uncertainty of spacecraft, conventional offline selected landmarks may be invalid and cause severe failure. To this end, the concept and calculation

Wingtip vortices have been proven to be detrimental to both aircraft efficiency and safety due to their adverse effects such as wake hazard, blade vortex interaction noise and induced drag. Despite the extensive literature on the subject, the number of experimental works featuring far field velocity measurements under active control is very limited. The present work deals with the experimental investigation

The goal of this paper is to investigate the effects of flow confinement on the noise generated by a small unmanned aerial system rotor measured and simulated in a partially closed test room. More specifically, the influence of the flow recirculation in the test room and the consequent blade turbulence interaction on both the tonal unsteady loading noise and the broadband laminar separation noise components