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lumped-parameter model for dynamic monolayer graphene sheets

JOURNAL OF SOUND AND VIBRATION 2022年 534卷

作者： Wei, Dongming Nurakhmetov, Daulet Aniyarov, Almir Zhang, Dichuan Spitas, Christos Nazarbayev Univ Sch Sci & Humanities 53 Kabanbay Batyr Ave Nur Sultan 010000 Kazakhstan Nazarbayev Univ Sch Engn & Digital Sci 53 Kabanbay Batyr Ave Nur Sultan 010000 Kazakhstan

In this paper, the dynamic Euler-Bernoulli PDE model based on the quadratic constitutive law are used for modeling of monolayer graphene sheets suspended in free vibration. The PDE model and corresponding lumped-parameter model are introduced. Analytical formulas for the lumped-parameter model and semi-analytic/numerical solutions of the model are presented by using several techniques of approximations. It is demonstrated analytically and numerically that the nonlinear quadratic term has a significant impact on the resonant frequency of the vibrating system. In additions to the numerical solution, the analytic solution obtained by the variational iteration method with Pade approximations indicates the existence of several natural frequencies of nonlinear models.

关键词： lumped-parameter model Graphene sheet Natural frequency Stiffness coefficient

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A lumped-parameter model for sound generation in gas metal arc welding

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MECHANICAL SYSTEMS AND SIGNAL PROCESSING 2021年 147卷 107085-107085页

作者： Zhao, Sipei Qiu, Xiaojun Burnett, Ian Rigby, Malcolm Lele, Anthony Univ Technol Sydney Fac Engn & IT Ctr Audio Acoust & Vibrat Sydney NSW Australia Sound Intuit Pty Ltd Melbourne Vic Australia

It is found that the welding sound generated in Gas Metal Arc Welding (GMAW) can help human welders to improve welding quality;however, little work has been reported on the sound generation and prediction in GMAW processes. To investigate the sound generation in GMAW, this paper proposes a lumped-parameter model to predict the sound signals at the short-circuiting mode in GMAW, where the power source is modeled by a simple resistor-inductor electrical circuit and the metal droplet dynamics is modeled by a mass-spring model. The simulation results of the welding current, arc voltage, and sound signals are found to be in a reasonable agreement with the experimental measurements. Both simulation and experiment results show that the welding current increases from a base value in the arcing phase to a peak value in the short-circuiting phase first and then slumps to the base value;the voltage is close to zero in the short-circuiting phase corresponding to the current peaks and fluctuates in the arcing phase due to the uncertainties in the arc resistance;and an acoustic impulse is formed at each peak current and valley voltage in the short-circuiting phase, indicating that the sound generation is related to the energy release during the arc re-ignition process. The proposed lumped-parameter model can be used to investigate the effect of the input welding parameters on the welding sound. (C) 2020 Elsevier Ltd. All rights reserved.

关键词： Gas metal arc welding Welding sound lumped-parameter model

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Implementation of the consistent lumped-parameter model for the computation of the seismic response of nonlinear piled structures 10

Implementation of the consistent lumped-parameter model for ...

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10th International Conference on Structural Dynamics (EURODYN)

作者： Gonzalez, Francisco Padron, Luis A. Aznarez, Juan J. Maeso, Orlando Univ Las Palmas Gran Canaria IUSIANI Edificio CentParque Cient & Tecnol Las Palmas Gran Canaria 35017 Spain

The computation of the nonlinear response of piled structures taking soil-structure interaction into account is tackled in this paper. The structure is assumed to be founded on a group of piles, whose impedance and kinematic interaction functions are computed, in the frequency domain, through a boundary elements-finite elements coupled formulation. On the other hand, the response of the system is computed using a time-stepping procedure for the integration of the equations of motion for an inelastic superstructure, which requires a time-domain representation of the above-mentioned impedance and kinematic interaction functions. This can be achieved by the use of different methodologies, such as standard lumped-parameter models, higher-order consistent lumped parameter models, or hidden state variable models, among others. In this paper, the use of high-order consistent lumped-parameter models for the deterministic representation of the impedance functions of deep foundations will be discussed together with different aspects of the resulting equivalent systems such as degree of accuracy, physical representation of parameters or arising numerical stability issues. Then, the use of this approach for the computation of the inelastic response of piled structures subject to seismic excitation will be explored. (C) 2017 The Authors. Published by Elsevier Ltd.

关键词： dynamic soil-structure interaction lumped-parameter model non-linear behaviour of structures piles

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lumped parameter model for Practical Compensation of the Sound with Bone Conduction Headphones 7

Lumped Parameter Model for Practical Compensation of the Sou...

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IEEE 7th Global Conference on Consumer Electronics (GCCE)

作者： Fujise, Akiko Panasonic Corp Tokyo Japan

ISBN: (纸本)9781538663097

Hearing devices with vibrators placed around the tragus or the cheek bone are adopted by some markets as "bone conduction headphones". Although the transmission pathways of bone-conducted sound are being identified, there needs to be more work to implement these findings into commercial bone conduction headphones to achieve the output equivalent to air conducted sound. This presentation thus introduces the lumped-parameter models for the excitation with BC headphones by referring to the models of the simulators for BC hearing aid and telephonometry.

关键词： bone conduction lumped-parameter model

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Implementation of the consistent lumped-parameter model for the computation of the seismic response of nonlinear piled structures

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Procedia Engineering 2017年 199卷 2360-2365页

作者： Francisco González Luis A. Padrón Juan J. Aznárez Orlando Maeso Instituto Universitario de Sistemas Inteligentes y Aplicaciones Numéricas en Ingeniería (IUSIANI) Universidad de Las Palmas de Gran Canaria Edificio Central del Parque Científico y Tecnológico del Campus Universitario de Tafira 35017 Las Palmas de Gran Canaria Spain

The computation of the nonlinear response of piled structures taking soil-structure interaction into account is tackled in this paper. The structure is assumed to be founded on a group of piles, whose impedance and kinematic interaction functions are computed, in the frequency domain, through a boundary elements-finite elements coupled formulation. On the other hand, the response of the system is computed using a time-stepping procedure for the integration of the equations of motion for an inelastic superstructure, which requires a time-domain representation of the above-mentioned impedance and kinematic interaction functions. This can be achieved by the use of different methodologies, such as standard lumped-parameter models, higher-order consistent lumped-parameter models, or hidden state variable models, among others. In this paper, the use of high-order consistent lumped-parameter models for the deterministic representation of the impedance functions of deep foundations will be discussed together with different aspects of the resulting equivalent systems such as degree of accuracy, physical representation of parameters or arising numerical stability issues. Then, the use of this approach for the computation of the inelastic response of piled structures subject to seismic excitation will be explored.

关键词： dynamic soil-structure interaction lumped-parameter model non-linear behaviour of structures piles

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Nested lumped-parameter model for Foundation with Strongly Frequency-dependent Impedance

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JOURNAL OF EARTHQUAKE ENGINEERING 2016年第6期20卷 975-991页

作者： Wang, Jue Zhou, Ding Liu, Weiqing Wang, Shuguang Nanjing Tech Univ Coll Civil Engn Mail Box 8020-3530 Puzhu Rd Nanjing 211816 Jiangsu Peoples R China

A nested lumped-parameter model (LPM) consisting of frequency-independent springs and dashpots is proposed to represent the foundation-soil dynamic system with strongly frequency-dependent impedance in time domain. Due to the convergence and robustness of the complex Chebyshev polynomial, it is used to approximate the dynamic flexibility of the foundation by least-square curve-fitting technique. The comparisons with existing LPMs show that the present model can express the impedance by using a small number of elements and reduce oscillation of the solution appearing in simple polynomial approximations. Finally, several examples of foundations with irregular geometries are presented to show the application of nested LPMs.

关键词： Soil-Structure Interaction lumped-parameter model Impedance Function Flexibility Function Complex Chebyshev Polynomial Nested Division

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lumped-parameter models Comparison for Natural Ventilation Analyses in Buildings at Urban Scale

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ENERGIES 2025年第9期18卷 2352-2352页

作者： Usta, Yasemin Ng, Lisa Santantonio, Silvia Mutani, Guglielmina Politecn Torino Dept Energy I-10129 Turin Italy Natl Inst Stand & Technol Gaithersburg MD 20899 USA

This study validates a three-zone lumped-parameter airflow model for Urban Building Energy modeling, focusing on its accuracy in estimating air change rates caused by natural ventilation, referred to here as air change rate. The model incorporates urban-scale variables like canyon geometry and roughness elements for the accurate prediction of building infiltration, which is an important variable in building energy consumption. Air change rate predictions from the three-zone lumped-parameter model are compared against results from a three-zone CONTAM model across a range of weather scenarios. The study also examines the impact of building level of detail on air change rates. Results demonstrate that the three-zone lumped-parameter model achieves reasonable accuracy, with a maximum Mean Absolute Error of 0.1 h-1 in winter and 0.03 h-1 in summer compared to three-zone CONTAM model, while maintaining computational efficiency for urban-scale energy consumption simulations. However, its applicability is limited to buildings within urban canyons rather than detached structures, due to the assumptions made in the methodology of the three-zone lumped-parameter model. The results also showed that the model had lower errors for low to mid-rise buildings since the simplification of a detailed high-rise building into a three-zone model alters the buoyancy effect;a 4-story building showed Mean Absolute Percentage Error of 7% and 5% for a typical winter and summer day respectively when a detailed and simplified three-zone models are compared, while the error for a 16-story building were 18% and 12%. The results of building air change rates are used as input data in an hourly energy consumption model at urban scale and validated against measured hourly consumption to test the effect of the calculated urban-scale hourly air change rates.

关键词： building ventilation infiltrations lumped-parameter model ACR CONTAM Urban Building Energy modeling place-based approach

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Development of lumped-parameter models for debris bed remelting analysis

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ANNALS OF NUCLEAR ENERGY 2025年 217卷

作者： Jian, Lijun Yu, Peng Zeng, Xiao Li, Liangxing Ma, Rubing Yuan, Yidan Ma, Weimin Tsinghua Univ Dept Engn Phys Beijing Peoples R China China Nucl Power Engn Co Ltd 117 Xisanhuanbeilu Beijing Peoples R China Xi An Jiao Tong Univ 28 Xianning West Rd Xian Peoples R China Royal Inst Technol Roslagstullsbacken 21 Stockholm Sweden

During postulated severe accidents of a light water reactor, a debris bed may form in the lower head of the reactor pressure vessel due to Fuel-Coolant Interaction (FCI), and re-melt into a molten pool if the debris bed is uncoolable. The debris bed remelting is therefore an important process in a severe accident scenario. To predict the dynamic process of debris bed remelting, a computer program is developed in the present study using lumped-parameter models. The melt in the lower head is split into different zones of molten metal, molten oxide and solid debris particles submerged in molten pools. Correlations are employed to calculate the heat transfer within each zone and between zones. The developed lumped-parameter code is employed to calculate the COREM experiments. The comparison of the simulation results with the experimental shows a reasonable agreement for melting processes of single-material and two-material debris beds. The code is also used to investigate some factors which may affect debris bed remelting, such as internal heating power, volume ratio of components, and thermophysical properties.

关键词： Severe accidents Debris bed remelting lumped-parameter model Program development Molten pool

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Transit time determination for a riverbank filtration system using oxygen isotope data and the lumped-parameter model

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HYDROLOGICAL SCIENCES JOURNAL-JOURNAL DES SCIENCES HYDROLOGIQUES 2014年第6期59卷 1109-1116页

作者： Karman, Krisztina Maloszewski, Piotr Deak, Jozsef Forizs, Istvan Szabo, Csaba Hungarian Acad Sci Inst Geol & Geochem Res Res Ctr Astron & Earth Sci H-1112 Budapest Hungary German Res Ctr Environm Hlth GmbH Helmholtz Zentrum Munchen Inst Groundwater Ecol D-85764 Neuherberg Germany GWIS Ltd H-2120 Dunakeszi Hungary Eotvos Lorand Univ Lithosphere Fluid Res Lab Dept Petr & Geochem H-1115 Budapest Hungary

The mathematical description of the lumped-parameter Dispersion model is presented, and its use for estimating transit time and proportion of river water in a riverbank filtration system on Szentendre Island (in the Danube River, Hungary) is assessed by applying stable oxygen isotope data. The modelling approach could only be used to analyse single oxygen-isotope peaks observed during a 6-month-long time series, because the mean input (Danube) concentration was very close to the output (well) concentration. The water level in the Danube varied, but the lumped-parameter approach is only applicable for steady-state conditions. Isotope data observed during quasi steady-state hydraulic conditions selected at medium and higher water levels were modelled. At low water levels the method could not be used because the O-18 content of the Danube water and of collector wells was similar.

关键词： riverbank filtration lumped-parameter model oxygen isotope Szentendre Island

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lumped-parameter model of foundations based on complex Chebyshev polynomial fraction

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SOIL DYNAMICS AND EARTHQUAKE ENGINEERING 2013年 50卷 192-203页

作者： Wang, Hai Liu, Weiqing Zhou, Ding Wang, Shuguang Du, Dongsheng Nanjing Univ Technol Coll Civil Engn Nanjing 210009 Jiangsu Peoples R China

This paper uses the complex Chebyshev polynomials to develop the lumped-parameter (L-P) model of foundations. The method is an important extension to the approach adopting polynomials to model the dynamic properties of the foundation. Using the complex Chebyshev polynomials can reduce the unexpected wiggling in the foundation modeling, which inevitably occurs if using the simple polynomials of high degree. In the present analysis, the normalized flexibility function of foundation is expressed in terms of complex Chebyshev polynomial fraction. Through the partial-fraction expansion the complex Chebyshev polynomial fraction is decomposed into two sets of basic discrete-element models. The parameters in the models are obtained through the least-square curve-fitting to the available analytical or on-site measurement results. The accuracy and validity of the L-P model is validated through the applications to the surface circular foundations, embedded square foundations and pile group foundations, respectively. It is shown that in general the present model has better accuracy and needs fewer parameters than the existing L-P models. (C) 2013 Published by Elsevier Ltd.

关键词： lumped-parameter model Complex Chebyshev polynomial fraction Foundation Dynamic impedance

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