bluuebunny/crossref_metadata_2025_split huggingface dataset:
A linearised Hybrid FE-SEA analysis method for complex systems with nonlinearities under random excitation
Authors: Allen H G , Langley R S 
Published: June 2024

Abstract
Within complex structures it is not uncommon for localised nonlinearities to be present, this renders conventional linear mid-high frequency analysis techniques such as the Hybrid Finite Element (FE) - Statistical Energy Analysis (SEA) method inapplicable. The development of a linearisation procedure applicable to an ensemble of random systems featuring deterministic nonlinearity is initially considered in this work, which is centred around the technique of Equivalent Linearisation. Constraining the linearisation to remain invariant across the whole ensemble, key to the linearised hybrid formulation developed, produced a relation between the order of both nonlinearity and the required statistical response moment when considered for Gaussian excitation. From the linearisation derived, an extension to hybrid variance theory was necessary to determine the variance of a frequency integrated response of the master system. A numerical study is then used to demonstrate the linearised Hybrid FE-SEA method against a series of Monte Carlo benchmark simulations adopting a Lagrange Rayleigh-Ritz model. The benchmark simulations feature different treatments of the nonlinearity from the linearisation developed to the full nonlinear solution.
Computation of the dynamic response of finite two-dimensional periodic structures
Authors: Duhamel Denis 
Published: June 2024

Abstract
The study of periodic media is mainly focused on one-dimensional periodic structures (periodic along one direction), to determine the dispersion curves or for the calculation of the response to an external excitation. Effective methods such as the Wave Finite Element (WFE) have been obtained for such computations. Two-dimensional periodic media are more complex to analyse but dispersion curves can be obtained rather easily. Obtaining their response to an excitation is much more difficult and the results mainly concern infinite media while for finite media, few results are available. In this communication, the response of finite two-dimensional periodic structures to an excitation is studied by limiting oneself to structures described by a scalar variable (acoustic, thermal, membrane behaviour) and having symmetries. Using the WFE for a rectangular substructure and imposing the wavenumber in one direction, we can calculate the wavenumbers and mode shapes associated with propagation in the perpendicular direction. By building solutions with null forces on parallel boundaries, we can decouple the waves in the two directions parallel to the sides of the rectangle and solve each case by a FFT. Summing the contributions of all these waves gives the global solution with a low computing time even for a large number of substructures. Examples are given for the case of a two-dimensional membrane.
A two-stage model updating using complex modal data
Authors: Henikish E , Bansal S 
Published: June 2024

Abstract
The process of Finite Element (FE) modelling is often associated with uncertainties which necessitates its updating using measured data. Updating dynamical model has a considerable importance in Structural Health Monitoring (SHM), estimating the structural responses, and structural control applications. Among the various presently available approaches for performing model updating, the probabilistic updating approach such as Bayesian model updating has gained a great deal of attention in the last two decades. It can aggregate all the types of uncertainties, e.g., prediction errors, modelling errors, measurement errors, etc., and deal with them as epistemic uncertainties about the system. This paper introduces a two-stage Bayesian model updating procedure of FE dynamical model. The targeted systems encounter a non-classical damping yielding complex modes of vibration. The original FE model is reduced using the method of dynamic condensation, where the reduced FE model is related to the observed Degrees-of-Freedoms (DOFs). Due to the usual availability of a limited number of sensors during real-world applications, modal data used to update the FE model is obtained from multiple setups. Finally, to simulate samples that approximate the posterior Probability Density Function (PDF), a new MWG sampling algorithm is used and compared with Transitional Markov Chain Monte Carlo (TMCMC) algorithm. The proposed approach has been applied to a numerical dynamical system with synthetic modal data acquired from multiple setups. Results revealed that the proposed approach could update the system’s uncertain parameters efficiently with a visible reduction in the uncertainty in both undamaged and damaged system.
SEA approach applied to the estimation of the vibroacoustic response of a statistical system excited through a nonlinear device
Authors: Andrade L , Langley R S 
Published: June 2024

Abstract
Statistical Energy Analysis (SEA) techniques have been largely employed to model vibroacoustic systems as it simplifies the equations of motion of the system optimising the computing time, a useful feature to analyse random ensembles. However, the approach is limited to linear systems. Modelling vibro-acoustic systems with nonlinear characteristics is a challenging problem as there rarely exist analytical solutions for the dynamic response. An example of a system that includes nonlinear features in the transmission path is the suspension system of a vehicle, where vibrations that are result of the interaction between the wheels and the road ultimately arise the sound pressure levels in the car cabin, which are affected by such nonlinearities. A nonlinear interface between the excitation point and a statistical structure has been included in an experimental setup that represents the suspension system with the aim of exploring key features, or otherwise, of the effect that a transmission path with nonlinear stiffness has on the structural response of a randomised statistical system to a random input. A numerical model has been developed to simulate the dynamic response of the structure by adopting the infinite plate assumption to model the statistical structure as an SEA dissipative mechanism, hence the equations of motion are largely simplified as they result in a single-degree-of-freedom second order differential equation. Numerical simulations of the model here developed agree remarkably well with the experimental data, where the averaged dynamic response and the generation of high-order harmonics are accurately estimated. Additionally, the measured loss of coherence at the frequencies where harmonics are present is also predicted by the model.
Smartdynamics a Mobile Phone Application Designed for Bridge Structural Assessments
Authors: Hassani Jihane Tahri , Teixeira Ricardo 
Published: June 2024

Abstract
A mobile phone application, referred to as SMARTdynamics, was developed to take site readings of the dynamic response of a cable-stayed highway bridge and a three-span plate girder railway bridge by making use of built-in accelerometers. The application allows to determine key dynamic properties including natural frequencies, displacements, and damping ratios. SMARTdynamics includes a novel feature for smartphone accelerometers: the ability to control the sensor remotely with automated application feedback, allowing to record the dynamic response at specific times and with precision. The aim of the study was to determine the reliability of smartphone accelerometers, establish the effectiveness of mobile phone usage in the bridges and civil structures industry, and demonstrate that the derivation of more realistic dynamic properties can offer benefits in determining less conservative structural capacities. Acceleration readings were taken for a cable-stayed highway bridge to determine the tension force within the stay cables. The obtained results confirmed the viability of mobile phone ac-celerometers as a serious asset management tool. Site readings were also taken to determine the dynamic amplification factors of plate girder railway bridges and revealed a mean average reduction of 40% in the real dynamic increment factor when compared with values derived from codes of practice. The study confirmed that moving towards a realistic approach to bridge structural assessments with user-friendly and cost-effective tools can have tangible benefits and should be considered as a viable alternative to traditional methods.
A Novel Reduced Column Approach for the Mitigation of Earthquake-Induced Vibrations of Wind Turbines
Authors: Tombari Alessandro , Rostami Rohollah 
Published: June 2024

Abstract
Wind power is a sustainable and renewable energy source which becomes fundamental in order to meet the worldwide rising demand for energy. New onshore and offshore wind farms will be rapidly constructed in challenging environments, especially in earthquake-prone areas. Although a flexible structure, the wind turbine tower is slender and lightly damped which may exhibit a high susceptibility to earthquake-induced vibration. Whilst past studies have been based on traditional passive control devices, such as tuned mass dampers or tuned liquid column dampers, this study aims to propose a novel approach, the Reduced Column Section (RCS), to design an innovative transition piece to mitigate the vibrations on fixed wind turbines. The novel transition piece of hourglass shape will allow the control of the fundamental period of the wind turbine as well as it will limit the maximum stresses within the device by protecting the tower and the monopile.
The proposed approach will be numerically tested on the 15MW benchmark wind turbine proposed by the International Energy Agency. A 3-dimensional finite element model will be generated using the commercial ADINA software and verified through the 1-dimensional baseline model provided for the open-source OPENFAST code. Therefore, the novel transition piece will be implemented and tested under a combination of multi-hazards such as wind and seismic loading. Two proposed devices, with and without auxetic lattice structure, will be investigated. The benefits of the proposed devices will be demonstrated in terms of the mitigation of the stresses on the tower wall and on the soil.
Identification of the dynamic properties of a fluid inerter
Authors: Chillemi M , Furtmüller T , Adam C , Pirrotta A 
Published: June 2024

Abstract
To control vibrations in structures, the mitigation effect of well-known passive control devices such as Tuned Mass Dampers can be used. Since the effectiveness of these devices strongly depends on their mass, the so-called inerter can be exploited to fictitiously increase their mass, allowing a mass amplification effect without any physical addition. The present study aims to identify the dynamic properties of a fluid inerter, consisting of a hydraulic cylinder connected by an external pipe filled with fluid. A test campaign is conducted to reveal the actual behavior of this device, focusing on the effects of its nonlinearities. Specifically, the following nonlinear effects are revealed: energy dissipation due to friction of the piston and pressure drops due to the viscosity of the fluid in the external pipe and at the inlet and outlet. An accurate mechanical model of the device is determined and its efficiency demonstrated by means of comparative numerical studies. The nonlinear layout provides more realistic response predictions than a common linear model and can be implemented in several structural control device configurations.
Hydroelastic analysis of flapping-foil thrusters using a partitioned BEM-FEM
Authors: Anevlavi D , Filippas E , Karperaki A , Belibassakis K 
Published: June 2024

AbstractUnderstanding the mechanics of aquatic locomotion has been an active field of research for decades and continues to inspire technological solutions ranging from small-scale propulsion systems for autonomous underwater vehicles (AUVs) to larger-scale energy saving devices (ESDs) for ships. The bio-inspired thrust-producing kinematics are shared among most flapping-foil systems, however joint experimental and numerical research suggests that incorporating additional biomimetic features, such as hydrodynamic shape and elasticity, in new designs can enhance the efficiency. Focusing on the latter, the response of passively deforming wings is implicitly non-linear, since deformations affect the hydrodynamic load excitation and vice-versa. Therefore, fluid-structure interaction simulations are essential for accurate predictions of the wings’ response. In the present work, a cost-effective computational tool is proposed for the hydroelastic analysis of flexible flapping-foil thrusters, which consists of a 3-D unsteady boundary element method (BEM) weakly coupled with a finite element solver (FEM) based on plate elements. The verification of the present method is accomplished by means of comparison against experimental data from the literature. The prediction capabilities and the limitations of the weakly coupled BEM-FEM are discussed. Finally, the proposed numerical tools serve as the building blocks for the fully coupled BEM-FEM scheme that is currently under development.
Structural reliability analysis using imprecise evolutionary power spectral density functions
Authors: Behrendt Marco , Dang Chao , Faes Matthias G.R. , Valdebenito Marcos A. , Beer Michael 
Published: June 2024

AbstractBuildings and structures in many regions of the world are exposed to environmental factors that can cause damage or failure, making it essential to model these factors accurately in engineering. Stochastic dynamics are crucial for modelling environmental processes, such as earthquake ground motions and wind loads, which can be characterised by a power spectral density (PSD) function that determines the dominant frequencies and corresponding amplitudes of the process. However, when generating a load model described by a PSD function, uncertainties in the processes must be taken into account, which makes a reliable estimation of the PSD function challenging, especially with only limited data available. This study employs the recently developed imprecise PSD function by using a radial basis function network to optimise data-enclosing bounds that produce an interval-valued PSD function. With this approach, a data set in the frequency domain can be bounded for uncertainty quantification. The method described in this work consists of optimising best-case and worst-case PSD functions within the bounds, which are transformed into a separable evolutionary PSD function. The reliability of structures is determined by an upper and lower failure probability, taking into account the present uncertainties. Advanced interval propagation schemes are linked to the imprecise PSD function to determine the failure probabilities efficiently. The method is illustrated by means of three numerical examples.
Probability of failure of nonlinear oscillators with fractional derivative elements subject to imprecise Gaussian loads
Authors: Ni P , Jerez D J , Fragkoulis V C , Mitseas I P , Faes M G R , Valdebenito M A , Beer M 
Published: June 2024

Abstract
In this paper, an approach for bounding the first-passage probability of a class of nonlinear oscillators with fractional derivative elements and subjected to imprecise stationary Gaussian loads is presented. Specifically, the statistical linearization and stochastic averaging methodologies are used in conjunction with an operator norm-based solution framework to estimate the bounds of the failure probability in a fully decoupled manner. The proposed technique can treat a wide range of nonlinear and hysteretic behaviors with relatively low computational cost. A numerical example is considered to demonstrate the applicability of the proposed approach. Specifically, the bounds of the first-passage probability of a bilinear hysteretic oscillator with fractional derivative elements are estimated.
Temperature Prediction Model Based on Low Temperature Release Method of Fire Extinguishing Bottle for Civil Aircraft Flight Test
Authors: Yu JiaZuo , Li Zheng , Feng Chao 
Published: June 2024

Abstract
In the fire extinguishing agent concentration flight test for the power plant system of modern civil aircraft, the low temperature release method of fire extinguishing bottle is usually used to make the test results more representative. Based on the implementation experience of a certain civil aircraft flight test, this paper discusses the detail of the low temperature release method and a critical temperature prediction model in flight test organization process. Also focus on the theoretical analysis, model establishment, model verification and model application of temperature prediction for fire extinguishing bottle. The model has been successfully used to predict the fire extinguishing bottle temperature in the flight test of a certain type aircraft. Improve the implementation success rate to 100%, which has great significance for the fire extinguishing agent concentration flight test. Likewise, it can also provide reference for other aircraft to carry out corresponding flight test.
Key technologies in photovoltaic power generation systems
Authors: Wang Ziming 
Published: June 2024

Abstract
With the increasing concern for environmental issues and the rising demand for renewable energy, photovoltaic (PV) power generation has gradually stepped into the public view. This paper provides a comprehensive literature review of key technologies in photovoltaic power generation systems, aiming to summarize and analyze the current state of research, trends and key issues in PV power generation systems. Inverters play a crucial role in PV power generation systems. The role of the inverter is not only to convert electrical energy, but also to ensure that the system can realize the most efficient energy conversion under different light conditions through advanced technologies such as maximum power point tracking. This paper provides a side-by-side comparison of several common tracking techniques from the maximum power point, including Perturb and Observe, Incremental Conductance and Fuzzy Logic Control. At last, this paper discusses future perspectives for photovoltaic power generation technology, including the development of new photovoltaic materials to improve photovoltaic conversion efficiency and cost, as well as the enhancement of the intelligence and integration of photovoltaic power generation systems. These improvements are aimed at promoting photovoltaic power generation technology in the direction of being more efficient, more reliable, more intelligent, and more sustainable.
All-dielectric metasurface for polarization-multiplexed single-pixel imaging
Authors: Wang Pengsen , Guo Kai , Guo Zhongyi 
Published: June 2024

Abstract
Integration and miniaturization of multi-channel single-pixel imaging systems have become a developing trend. However, it is challenging to meet such development needs solely relying on traditional optical devices. One feasible solution is the utilization of metasurfaces with multiplexing functionality. Here, we propose and validate an all-dielectric, anisotropic metasurface that provides a random mask with polarization multiplexing for single pixel imaging. The design ensures each mask contains 50% target information, allowing adaptive correlated imaging of different targets without needing to redesign the masks. By optimizing the metasurface, we enhance computational efficiency by preventing correlation between different polarization channels and mask patterns. We also adjust the parameters of the compressed sensing algorithm to accommodate various sampling rates, ensuring high-quality image reconstruction. Additionally, the whole system is simulated by the angular spectrum transmission and compressed sensing reconstruction algorithm, providing image reconstruction results for metasurfaces of different sizes, demonstrating the feasibility of the proposed approach. It is noteworthy that the designed metasurface works for single-wavelength operation and could be extended to multispectral imaging by introducing achromatic metasurface technology. The proposed method could miniaturize the optical devices and reduce light loss.
Analysis of speckle-beacon size impact on wavefront sensing and closed-loop control in deep turbulence conditions
Authors: Vorontsov Mikhail A , Lachinova Svetlana L , Polnau Ernst 
Published: June 2024

Abstract
The impact of the laser beacon size on the performance of an ideal phase-conjugation-type adaptive optics (AO) system is analyzed using wave-optics-based numerical simulation. The analysis includes wavefront aberration sensing and closed-loop control for laser beam propagation both in vacuum and in distributed (volume) atmospheric turbulence with the beacon beam scattering off a flat extended target with Lambertian surface roughness. For mitigation of the impact of target-induced speckle effects on the performance of AO systems, speckle-average wavefront sensing and control approaches are introduced and analyzed. The results demonstrate that proposed speckle-average phase conjugation control algorithms enable partial mitigation of turbulence-induced aberrations in presence of strong speckle modulations.
A single-phase grid-tied extendable-level inverter for renewable energy applications
Authors: Aishwarya V 
Published: June 2024

Abstract
The extraction of power from green energy sources (GES) has rapidly popularized owing to increasing energy demands, depletion of fossil fuels and growing concerns about climatic changes. Grid-tied multilevel inverters are critical components in the integration of green energy sources into the power grid and offer numerous benefits over standard two-level inverters. These benefits include superior power quality, diminished harmonic distortion, and the potential to utilize high power levels efficiently. A single-phase Grid-Tied Extendable-Level Inverter (GTELI) for green energy applications is demonstrated in this paper. The GTELI offers superior power quality and distortion-free output relative to existing grid-tied multilevel inverters and hence is an excellent choice for extracting power from sustainable energy sources. To ensure efficient utilization, the extracted power from GTELI is to be integrated into the supply grid. A new current control algorithm for the GTELI is also proposed in this paper. Using this current control technique a grid control technique is established to modulate the power flow to the grid. The proposed GTELI achieved sinusoidal grid voltage and injected current with minimised harmonic distortions of 1.6% and 2.7% respectively, which comply well with the tolerable range of the IEEE 519 standard.