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  • Open Access

    ARTICLE

    Parameter Optimization of Tuned Mass Damper Inerter via Adaptive Harmony Search

    Yaren Aydın1, Gebrail Bekdaş1,*, Sinan Melih Nigdeli1, Zong Woo Geem2,*

    CMES-Computer Modeling in Engineering & Sciences, Vol.141, No.3, pp. 2471-2499, 2024, DOI:10.32604/cmes.2024.056693 - 31 October 2024

    Abstract Dynamic impacts such as wind and earthquakes cause loss of life and economic damage. To ensure safety against these effects, various measures have been taken from past to present and solutions have been developed using different technologies. Tall buildings are more susceptible to vibrations such as wind and earthquakes. Therefore, vibration control has become an important issue in civil engineering. This study optimizes tuned mass damper inerter (TMDI) using far-fault ground motion records. This study derives the optimum parameters of TMDI using the Adaptive Harmony Search algorithm. Structure displacement and total acceleration against earthquake load More >

  • Open Access

    ARTICLE

    HQNN-SFOP: Hybrid Quantum Neural Networks with Signal Feature Overlay Projection for Drone Detection Using Radar Return Signals—A Simulation

    Wenxia Wang, Jinchen Xu, Xiaodong Ding, Zhihui Song, Yizhen Huang, Xin Zhou, Zheng Shan*

    CMC-Computers, Materials & Continua, Vol.81, No.1, pp. 1363-1390, 2024, DOI:10.32604/cmc.2024.054055 - 15 October 2024

    Abstract With the wide application of drone technology, there is an increasing demand for the detection of radar return signals from drones. Existing detection methods mainly rely on time-frequency domain feature extraction and classical machine learning algorithms for image recognition. This method suffers from the problem of large dimensionality of image features, which leads to large input data size and noise affecting learning. Therefore, this paper proposes to extract signal time-domain statistical features for radar return signals from drones and reduce the feature dimension from 512 × 4 to 16 dimensions. However, the downscaled feature data… More >

  • Open Access

    PROCEEDINGS

    Topology Optimization Method Considering Nonlinear Fatigue Damage Accumulation in Time Domain

    Jinyu Gu1, Yingjun Wang1,*

    The International Conference on Computational & Experimental Engineering and Sciences, Vol.29, No.2, pp. 1-1, 2024, DOI:10.32604/icces.2024.010958

    Abstract In engineering practice, most components are subjected to variable-amplitude cyclic loading, resulting in fatigue damage, which is one of the main forms of damage in engineering structures. Nonlinear damage rule is developed based on linear damage rule, which can predict the fatigue life of structures more accurately. Therefore, we present a topology optimization method considering nonlinear fatigue damage accumulation in the time domain. For the time domain, we adopted the rainflow counting method to evaluate the stress level generated by cyclic loading and the Basquin equation to describe the S-N curve. We applied Morrow's plastic… More >

  • Open Access

    ARTICLE

    Distributed Dynamic Load in Structural Dynamics by the Impulse-Based Force Estimation Algorithm

    Yuantian Qin1,2, Yucheng Zhang1,*, Vadim V. Silberschmidt2

    CMES-Computer Modeling in Engineering & Sciences, Vol.139, No.3, pp. 2865-2891, 2024, DOI:10.32604/cmes.2024.046113 - 11 March 2024

    Abstract This paper proposes a novel approach for identifying distributed dynamic loads in the time domain. Using polynomial and modal analysis, the load is transformed into modal space for coefficient identification. This allows the distributed dynamic load with a two-dimensional form in terms of time and space to be simultaneously identified in the form of modal force, thereby achieving dimensionality reduction. The Impulse-based Force Estimation Algorithm is proposed to identify dynamic loads in the time domain. Firstly, the algorithm establishes a recursion scheme based on convolution integral, enabling it to identify loads with a long history More >

  • Open Access

    REVIEW

    Harmonic Balance Methods: A Review and Recent Developments

    Zipu Yan1,2, Honghua Dai1,2,*, Qisi Wang1,2, Satya N. Atluri3

    CMES-Computer Modeling in Engineering & Sciences, Vol.137, No.2, pp. 1419-1459, 2023, DOI:10.32604/cmes.2023.028198 - 26 June 2023

    Abstract The harmonic balance (HB) method is one of the most commonly used methods for solving periodic solutions of both weakly and strongly nonlinear dynamical systems. However, it is confined to low-order approximations due to complex symbolic operations. Many variants have been developed to improve the HB method, among which the time domain HB-like methods are regarded as crucial improvements because of their fast computation and simple derivation. So far, there are two problems remaining to be addressed. i) A dozen of different versions of HB-like methods, in frequency domain or time domain or in hybrid,… More >

  • Open Access

    ARTICLE

    4-Port Octagonal Shaped MIMO Antenna with Low Mutual Coupling for UWB Applications

    Mahmoud A. Abdelghany1,4, Mohamed Fathy Abo Sree2, Arpan Desai3, Ahmed A. Ibrahim4,*

    CMES-Computer Modeling in Engineering & Sciences, Vol.136, No.2, pp. 1999-2015, 2023, DOI:10.32604/cmes.2023.023643 - 06 February 2023

    Abstract A 4-port multiple-input multiple-output (MIMO) antenna exhibiting low mutual coupling and UWB performance is developed. The octagonal-shaped four-antenna elements are connected with a 50 Ω microstrip feed line that is arranged rotationally to achieve the orthogonal polarization for improving the MIMO system performance. The antenna has a wideband impedance bandwidth of 7.5 GHz with S11 < −10 dB from (103.44%) 3.5–11 GHz and inter-element isolation higher than 20 dB. Antenna validation is carried out by verifying the simulated and measured results after fabricating the antenna. The results in the form of omnidirectional radiation patterns, peak gain (≥4 dBi), and Envelope Correlation Coefficient (ECC) (≤0.01) More > Graphic Abstract

    4-Port Octagonal Shaped MIMO Antenna with Low Mutual Coupling for UWB Applications

  • Open Access

    ARTICLE

    Analysis of OSA Syndrome from PPG Signal Using CART-PSO Classifier with Time Domain and Frequency Domain Features

    N. Kins Burk Sunil1, *, R. Ganesan2, B. Sankaragomathi3

    CMES-Computer Modeling in Engineering & Sciences, Vol.118, No.2, pp. 351-375, 2019, DOI:10.31614/cmes.2018.04484

    Abstract Obstructive Sleep Apnea (OSA) is a respiratory syndrome that occurs due to insufficient airflow through the respiratory or respiratory arrest while sleeping and sometimes due to the reduced oxygen saturation. The aim of this paper is to analyze the respiratory signal of a person to detect the Normal Breathing Activity and the Sleep Apnea (SA) activity. In the proposed method, the time domain and frequency domain features of respiration signal obtained from the PPG device are extracted. These features are applied to the Classification and Regression Tree (CART)-Particle Swarm Optimization (PSO) classifier which classifies the More >

  • Open Access

    ARTICLE

    Applying a Step Approach Method in Solving the Multi-Frequency Radiation From a Complex Obstacle

    Jui-Hsiang Kao1

    CMES-Computer Modeling in Engineering & Sciences, Vol.112, No.1, pp. 59-73, 2016, DOI:10.3970/cmes.2016.112.059

    Abstract In this paper, a step approach method in the time domain is developed to calculate the radiated waves from an arbitrary obstacle pulsating with multiple frequencies. The computing scheme is based on the Boundary Integral Equation and derived in the time domain; thus, the time-harmonic Neumann boundary condition can be imposed. By the present method, the values of the initial conditions are set to zero, and the approach process is carried forward in a loop from the first time step to the last. At each time step, the radiated pressure on each element is updated. More >

  • Open Access

    ARTICLE

    A RIM-based Time-domain Boundary Element Method for Three-Dimensional Non-homogeneousWave Propagations

    Liu Liqi1, Wang Haitao1,2

    CMES-Computer Modeling in Engineering & Sciences, Vol.109-110, No.4, pp. 303-324, 2015, DOI:10.3970/cmes.2015.109.303

    Abstract This paper presents a three-dimensional (3-D) boundary element method (BEM) scheme based on the Radial Integration Method (RIM) for wave propagation analysis of continuously non-homogeneous problems. The Kelvin fundamental solutions are adopted to derive the boundary-domain integral equation (BDIE). The RIM proposed by Gao (Engineering Analysis with Boundary Elements 2002; 26(10):905-916) is implemented to treat the domain integrals in the BDIE so that only boundary discretization is required. After boundary discretization, a set of second-order ordinary differential equations with respect to time variable are derived, which are solved using the Wilson-q method. Main advantages of More >

  • Open Access

    ARTICLE

    Mixed Unsplit-Field Perfectly Matched Layers for Plane-Electromagnetic-Wave Simulation in the Time Domain

    Sang-Ri Yi1, Boyoung Kim2, Jun Won Kang2,3

    CMES-Computer Modeling in Engineering & Sciences, Vol.106, No.2, pp. 77-104, 2015, DOI:10.3970/cmes.2015.106.077

    Abstract This study is concerned with the development of new mixed unsplitfield perfectly matched layers (PMLs) for the simulation of plane electromagnetic waves in heterogeneous unbounded domains. To formulate the unsplit-field PML, a complex coordinate transformation is introduced to Maxwell's equations in the frequency domain. The transformed equations are converted back to the time domain via the inverse Fourier transform, to arrive at governing equations for transient electromagnetic waves within the PML-truncated computational domain. A mixed finite element method is used to solve the PML-endowed Maxwell equations. The developed PML method is relatively simple and straightforward More >

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