Twin-entry radial turbine has an evident advantage of enhancing the output power in internal combustion engine, while it is confronted by complex inlet conditions because of the interval flow feeding into two limbs. Although the performance of twin-entry turbine is notably influenced by admission conditions, detailed flow mechanism is yet fully revealed in previous researches. This paper investigates

This paper establishes a mathematical model to analyze the static and dynamic behaviors of functionally graded graphene reinforced composite (FG-GRC) beam with geometric imperfection subjected to thermo-electro-mechanical load. Three different geometric imperfections are considered. Four different distribution patterns of graphene nanoplatelets (GPLs) are taken into consideration. The effective properties

Assessment of the geometrically nonlinear forced vibration of the doubly-curved laminated composite shallow shell panels enriched by nanocomposites have been carried out in this paper. The proposed shells incorporate some layers composed of fibres and nanocomposite-reinforced resin, resting on the two types Winkler and Pasternak elastic foundations. Since the thin and moderately thick shells are investigated

Vibro-impact (VI) phenomenon can be used in vibration absorbers to reduce low frequency vibrations on a fast time scale. VI absorbers are effective on a wide range of frequency, they are also known to be robust and insensitive to temperature changes, and they do not rely on visco-elastic materials. This solution offers very interesting and promising possibilities for vibration suppression in harsh

The novel non-contact spacecraft can achieve physical vibration isolation through the non-contact Lorentz actuator (NCLA), thereby providing ultra-high payload pointing accuracy and stability. However, due to the change in the relative position of magnet and coil, the NCLA can ensure accurate control input only in the linear working range, but not in the entire air-clearance range. To address this

This work aims to develop a Structural Health Monitoring methodology that maximizes the acquired modal response and minimizes the number of sensors in a helicopter’s main rotor blade. Although this trade-off is a SHM principle, there is no methodology in literature that opposes these objectives for any structure. Firstly, a real AS350 helicopter rotor blade was experimentally tested and a numerical

In this work angular velocity solutions are presented from accelerometers. Two main formulations are presented. The first is based on using multiple vector sets of accelerometers, and the second is based on using multiple single-axis accelerometers. Linear least-squares approaches are derived for both, along with error-covariance expressions for the angular velocity estimates. Nonlinear least-squares

Spacecraft on-orbit inspection provides a prerequisite for the subsequent autonomous proximity operations. To fulfill the mission, robust constrained control algorithms for relative position tracking and attitude adjustment should be employed to handle the nonlinear coupled dynamics, system constraints, and external disturbances. In this paper, a robust nonlinear model predictive control (NMPC) scheme

The problem of triaxial attitude stabilization of a satellite in the orbital frame is considered. The problem is raised about the possibility of implementing such a system of electrodynamic attitude control by the type of a PID controller in which the restoring component of the control torque contains a distributed delay. A constructive analytical approach to the nonlinear stability analysis in the

The unscented Kalman filter (UKF) is a promising method for system state and structural parameters estimation. However, its performance depends on the process noise and measurement noise covariance matrices, which are usually unknown in practice. Arbitrary selection of these covariance matrices may lead to unreliable or even diverging estimation results. To resolve this critical problem, we propose

In this article, the formulation of Lagrange Multiplier State-Space Substructuring (LM-SSS) is presented and extended to directly compute coupled displacement and velocity state-space models. The LM-SSS method is applied to couple and decouple state-space models established in the modal domain. Moreover, it is used together with tailored post-processing procedures to eliminate the redundant states

Modern and future high precision pointing space missions face increasingly high challenges related to the widespread use of large flexible structures. The development of new modeling tools which are able to account for the multidisciplinary nature of this problem becomes extremely relevant in order to meet both structure and control performance criteria. This paper proposes a novel methodology to analytically

We consider two cantilevered beams undergoing frictional impacts at the free end. The beams are designed to be of similar geometry so that they have distinct but close natural frequencies. Under harmonic base excitation near the primary resonance with the higher-frequency fundamental bending mode, the system shows a strongly modulated non-periodic response. The purpose of this work is to analyze to

Active control has been applied to base-isolated buildings to achieve high control performance. A base-isolated building with active control has many design parameters, such as parameters of the superstructure, isolator, viscous dampers, and hysteretic dampers. The conventional control-system design uses trial-and-error approaches to select these design parameters and numerical simulations to estimate

The dynamics of swinging bells is a timely problem considered when the bell’s supporting structures are designed or monitored. The geometry of a yoke and the magnitude of an excitation force are crucial parameters determining a yoke–bell–clapper system response for a given shape and size of the bell. This paper presents the novel yoke–bell–clapper system with variable geometry and adjustable excitation

The Power Spectral Density Transmissibility (PSDT) is a new tool for Operational Modal Analysis (OMA) under non-white ambient excitation. However, the current PSDT-based methods present certain challenges: the spurious modes originating from the non-white excitation cannot be fully eliminated under certain load cases and closely-spaced structural modes cannot be identified. This study gives an insight

A failure-informed enrichment algorithm is devised to improve the performance of the existing adaptive Kriging-probability density evolution method (AK-PDEM) for reliability analysis. This improved method is named the AK-PDEMi. Contrary to empirically prescribing the sample size of representative points in the existing AK-PDEM, the representative point set in the AK-PDEMi is sequentially enriched by

This study presents a novel transfer learning (TL)-based multi-fidelity modeling approach for a set of granular material-filled particle dampers (PDs) with varying cavity height and particle filling ratio, targeting to realize vibration/noise mitigation across a broad frequency band. The dynamic characteristics of this kind of dampers are highly nonlinear and depend on a number of features such as

A semi-analytical method is proposed for moving force identification (MFI) based on the finite element model of the bridge structures. The moving force can be expanded by a set of cosine basis functions based on the discrete cosine transform (DCT) in the time domain. By constructing the segmented continuous mode shape of the bridge deck, the analytical relationship between the measured acceleration

Wheel-rail squeal noise during train turning has been a tricky problem influencing passengers and nearby residents. The tonal curve squeal that mainly occurs at the inner rail has been extensively studied, while the broadband flange squeal that takes place at the outer rail that can be equally annoying is seldom mentioned and hardly investigated. This paper presents a study aiming at understanding

In recent years, research related to smart manufacturing processes, which aim to advance production technology through productivity improvement and manufacturing technology innovation, has been actively pursued. In the field of sheet metal press forming, intelligent process management is required to improve productivity and reduce costs. In this field, a method of indirectly monitoring signals generated

Rolling bearings are one of the most widely used bearings in industrial machines. The technical condition of the rolling bearings has a significant impact on the total condition of rotating machinery. Typically, the rolling bearing condition monitoring is based on signal processing from accelerometers mounted on the machine housing. AI-based signal processing methods allow achieving high results in

The balance of lateral and directional static stability plays an important role in the lateral-directional dynamics and vehicle design. The theory of geometric influence on the lateral and directional static stability is mature for conventional aircrafts. However, the distinct configuration characteristics and flow physics for hypersonic vehicles may lead to different design theory, which is absent

The main novelties and capabilities of the second version of the Bare Electrodynamic Tether Mission Analysis Software (BETsMA v2.0) are presented. Recent advances on Orbital-Motion-Theory have been incorporated to the electric model of Low-Work-function Tethers (LWTs). An electric model that considers a switch to embed a power supply or a resistor between a Bare Electrodynamic Tether (BET) and an electron

In order to obtain better aerodynamic efficiency and take-off/landing capacity, it will be a excellent configuration for distributed electric propulsion (DEP) aircraft to install the blown flap in the propulsion wake. For this configuration, the coupling motion between the blown flap and the duct is hard to be achieved by the transmission mechanism of traditional distributed electric propulsion aircraft

The efforts for the computational investigation and validation of different Missile Configurations tested at the U.S. Air Force Academy are summarized. The missile configurations considered have a streamlined body fitted with upstream strakes and cruciform all-movable tail fin surfaces and include: 1) a baseline with no fin deflection 2) a Roll10 configuration in which all fin surfaces are deflected

A novel windowed multi-resolution Dynamic Mode Decomposition (wmrDMD) technique was developed to obtain a data-driven model from experimental measurements and allow for an increase in temporal resolution of the measured data. The novel data-driven analysis technique was applied to two-dimensional motion-capturing Pressure Sensitive Paint (PSP) data of the pressure field over a wing in a flutter. The

The aim of this work is to investigate the performance of a solar sail-based spacecraft in an optimal apse line rotation maneuver. Considering a heliocentric two-body motion and a low-performance solar sail with an ideal force model, this study derives the optimal steering law that maximizes the final rotation angle of the osculating orbit apse line. Starting from an approximated (Gaussian) form of

Successful sampling on asteroids is challenging due to their weightless environment and unknown material mechanical properties. This work presents a sweeping and grinding combined hybrid sampler (SGHS) to improve the sampling success rate. The SGHS has two working modes, i.e., using two brush wheels to collect regolith and rock pieces and employing a drill bit to grind rocky surfaces into particles

A thorough understanding of the effects of sloshing on aircraft dynamic loads is of great relevance for the future design of flexible aircraft to be able to reduce their structural mass and environmental impact. Indeed, the high vertical accelerations caused by the vibrations of the structure can lead to the fragmentation of the fuel free surface. Fluid impacts on the tank ceiling are potentially a

The present work investigates the postbuckling, and postbuckled vibration behaviour of initially imperfect trapezoidal sandwich plates with functionally graded carbon nanotube reinforced composite (FG-CNTRC) face sheets and FG porous metal foam core under the influence of non-uniform edge compression. The plate's kinematic assumptions are based on a refined higher order theory and the strain-displacement

This paper investigates the effects of different automation design philosophies for a helicopter navigation task. A baseline navigation display is compared with two more advanced systems: an advisory display, which provides a discrete trajectory suggestion; and a constraint-based display, which provides information about the set of possible trajectory solutions. The results of a human-in-the-loop experiment

Bloch mode synthesis (BMS) is a model order reduction method that was originally formulated to accelerate band-structure calculations of periodic elastic materials. In this paper, the BMS framework is expanded to offer a platform suitable for analysis of electroelastic metamaterials with piezoelectric resonant shunt damping. First, a transformation of coordinates formed by a set of dominant fixed-interface

This paper presents the design, modelling, analysis, and test of a piezo-actuated dual-drive linear motion system, capable of millimeter stroke with nanometer resolution. The primary actuator is a two-stage bridge-type amplifier with hybrid flexure hinges, which is driven by a piezo-stack actuator and generates output stroke greater than 6 mm. The micro actuation is directly driven by an extra piezo-stack

The singular spectrum decomposition (SSD) is an effective signal denoising tool and has been attracted much attention in fault diagnosis. However, the filtering effect and calculation efficiency of SSD are seriously affected by the embedding dimension of trajectory matrix. To overcome these disadvantages, the improved SSD (ISSD) is proposed in this paper. A length factor is designed to optimize the

The present paper introduces a novel Bayesian filter for estimating mechanical excitation sources in the time domain from a set of vibration measurements. The proposed filter is derived from a very general Bayesian formulation, unifying most of the state-of-the-art recursive filters developed in the last decade for solving input-state estimation problems. More specifically, the proposed Bayesian filter

The ultrasonic method has been widely applied to measure the oil film thickness – a critical variable that reflects lubrication conditions. However, due to the thermal dependence of ultrasonic signals, significant deviations in film thickness measurements are introduced, hindering the in-situ application of the ultrasonic technique. To address this issue, a real-time temperature compensation method

This paper describes an accurate model of the Electrical Power Subsystem (EPS) of the Thermal Analysis Support and Environment Characterization Laboratory (TASEC-Lab), a university experiment developed for using in high-altitude balloon missions to measure and analyze the convection heat transfer. A Li-ion battery and two high efficient DC-DC converters have been characterized through laboratory tests

The number of space debris has rapidly increased in the recent times with the rising number of space missions. Thus, to ensure the safety of any operating satellite, collision avoidance maneuvers must be performed. It is also practically impossible to make the state measurements and dynamic models completely error-free. So, this study deals with fuel-optimal collision avoidance maneuvers while also

The shock wave/turbulent boundary layer interaction (SWBLI) exists widely in the internal and external supersonic flow field. The interaction of shock waves with turbulent boundary layers will induce serious separation. As a result, the flow field structure changes greatly. This leads to an increase in the flow field instability, total pressure loss, local peak heat flux, and other adverse effects

The attention of the international space community has been drawn to space weather over the last two decades, not only because of its uncertainty and its adverse effects on the safety of space operations and the long-term sustainability of outer space activities (LTSOSA), but also because of its negative societal and economic impacts on the ground. The national emergency management of space weather

Spacecraft are required to achieve fast attitude reorientation in many space missions. However, the attitude maneuver will be limited by the bounded and pointing constraints. The presence of these complex multiaxis constraints will largely reduce the feasible attitude space and greatly degrade the solving efficiency of the planning algorithm. For the time-optimal spacecraft reorientation problem under

The main contribution of this study is to propose an efficient and straightforward numerical model for exploring size-dependent geometrically nonlinear static and dynamic characteristics of functionally graded microplates reinforced by graphene nanofillers. To accomplish this purpose, modified couple stress theory including only one material length scale parameter is utilized to capture the size-dependent

Numerical investigation of swirling flows in a trapped-vortex combustor (TVC) is carried out using large eddy simulation (LES). A multi-block flow solver is employed to solve three-dimensional filtered compressible Navier-Stokes equations in generalized coordinate system through the use of high-order compact differencing schemes. The effect of swirl strength on the behavior of swirling flow features

This work presents a novel approach for the modelling of the regression rate in hybrid rocket engines loaded with paraffin-fuel. Two different motor thrust classes have been considered in this work to extend the validity of the numerical model on two motor geometries (200N and 1kN). The work consists of two parts. Firstly, a unique and general empirical law of the regression rate was found for both

This paper studies the dynamic properties of a 3D chiral mechanical metamaterial, which largely depend on tacticity describing the connection forms of the chiral unit. Based on the finite element theory and Bloch's theorem, a dynamic model of the 3D chiral mechanical metamaterial is established to analyze the band structures and transmission responses. The isotactic configuration converts longitudinal

In this paper, to increase the performance of the sparse reconstruction method in real complex engineering structures an adaptive dictionary learning framework is proposed which updates the dictionary matrix, to allow improved compatibility with the complex structure. This proposed framework was developed by combining analytical modeling with training data sets and learning methods. An experimental

When the Artemis missions launch, NASA's Orion spacecraft (and crew as of the Artemis II mission) will be exposed to the deep space radiation environment beyond the protection of Earth's magnetosphere. Hence, it is essential to characterize the effects of space radiation, microgravity, and the combination thereof on cells and organisms, i.e., to quantify any correlations between the deep space radiation

The increasing number of man-made objects in near-earth space is becoming a serious problem for future space missions around the Earth. Among the proposed strategies to face this issue, and due to its passive and propellant-less character, electrodynamic tethers appear to be a promising option for spacecraft in low Earth orbits thanks to the limited storage mass and the minimum interface requirements

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Abstract not available

This work develops a computational analysis framework of an axisymmetric two-stream nozzle for wrap-around combined cycle engines from the aspects of contour design methodology, design feasibility, and performance augmentation technology. This research proposes a modular design method that combines the inverse design for upstream turbojet/ramjet nozzles and the maximum thrust design for the collective

The pressure distribution around wedge models inside a submillimeter supersonic wind tunnel was experimentally investigated using pressure-sensitive paint (PSP) at a flow speed of Mach 1.6. The throat of the submillimeter supersonic wind tunnel was 500 μm. The two wedge models were isosceles triangles with a width of 50 μm and vertex angles of 20° and 30°, respectively. The pressure profiles and pressure

In this paper, a new design of auxetic honeycomb is proposed for mechanical performance enhancement by combining the arc-shaped wall and the normal double-arrowed auxetic configuration. On basis of Mohr's 2nd theorem and Castigliano 2nd theorem, an analytical model considering strut bending and stretching is developed to modulate the in-plane mechanical properties of the proposed honeycomb with the

There are two fundamental strategies in the design of metamaterials used for noise and vibration control. The first uses structural periodicity and explores the Bragg scattering to produce frequency ranges where waves do not propagate or are severely attenuated (stop-bands). This condition is usually limited by the constitutive size of the structural elements and tends to occur at higher frequencies