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  • Open Access

    ARTICLE

    Quantum dynamics of dissipative Chern insulator

    Jilian Zhong1, Xiaoyue Li1

    Revista Internacional de Métodos Numéricos para Cálculo y Diseño en Ingeniería, Vol.40, No.2, pp. 1-7, 2024, DOI:10.23967/j.rimni.2024.05.008 - 04 June 2024

    Abstract For open quantum systems, a short-time evolution is usually well described by the effective non-Hermitian Hamiltonians, while long-time dynamics requires the Lindblad master equation,in which the Liouvillian superoperators characterize the time evolution. In this paper, we constructed an open system by adding suitable gain and loss operators to the Chen insulator to investigate the time evolution of quantum states at long times by numerical simulations. Finally, we also propose a topolectrical circuits to realize the dissipative system for experimental observation. It is found that the opening and closing of the Liouvillian gap leads to different More >

  • Open Access

    ARTICLE

    Investigation of the Damping Abilities of Sheep Wool Reinforced Expanded Polystyrene Core Layer Composites at Different Energies

    İbrahim Yavuz1,*, Ercan Şimşir1, Kenan Budak2

    Journal of Polymer Materials, Vol.41, No.1, pp. 1-14, 2024, DOI:10.32604/jpm.2024.052279 - 21 June 2024

    Abstract In this study, natural fiber reinforced polymer foam core layered composites were produced for the automotive industry. Sheep wool was used as natural fiber. Polymer foam with a single layer XPS foam structure was used as the core material. XPS foams and fibers are bonded to the upper and lower sides of the foams with the help of resin. Samples were produced with one and two layers on both sides, with a total of two and four layers. Production was carried out using the vacuum bagging method using the manual laying method. After the production More >

  • Open Access

    ARTICLE

    Prediction of Damping Capacity Demand in Seismic Base Isolators via Machine Learning

    Ayla Ocak1, Ümit Işıkdağ2, Gebrail Bekdaş1,*, Sinan Melih Nigdeli1, Sanghun Kim3, Zong Woo Geem4,*

    CMES-Computer Modeling in Engineering & Sciences, Vol.138, No.3, pp. 2899-2924, 2024, DOI:10.32604/cmes.2023.030418 - 15 December 2023

    Abstract Base isolators used in buildings provide both a good acceleration reduction and structural vibration control structures. The base isolators may lose their damping capacity over time due to environmental or dynamic effects. This deterioration of them requires the determination of the maintenance and repair needs and is important for the long-term isolator life. In this study, an artificial intelligence prediction model has been developed to determine the damage and maintenance-repair requirements of isolators as a result of environmental effects and dynamic factors over time. With the developed model, the required damping capacity of the isolator… More >

  • Open Access

    ARTICLE

    Influence of Trailing-Edge Wear on the Vibrational Behavior of Wind Turbine Blades

    Yuanjun Dai1,2,*, Xin Wei1, Baohua Li1, Cong Wang1, Kunju Shi1

    FDMP-Fluid Dynamics & Materials Processing, Vol.20, No.2, pp. 337-348, 2024, DOI:10.32604/fdmp.2023.042434 - 14 December 2023

    Abstract To study the impact of the trailing-edge wear on the vibrational behavior of wind-turbine blades, unworn blades and trailing-edge worn blades have been assessed through relevant modal tests. According to these experiments, the natural frequencies of trailing-edge worn blades −1, −2, and −3 increase the most in the second to fourth order, the fifth order increases in the middle, and the first order increases the least. The damping ratio data indicate that, in general, the first five-order damping ratios of trailing-edge worn blades −1 and trailing-edge worn blades −2 are reduced, and the first five-order More >

  • Open Access

    PROCEEDINGS

    Damping Properties in Gradient Nano-Grained Metals

    Sheng Qian1, Qi Tong1,*

    The International Conference on Computational & Experimental Engineering and Sciences, Vol.27, No.3, pp. 1-1, 2023, DOI:10.32604/icces.2023.010116

    Abstract Applications such as aircrafts and electronic devices require the noise and vibration reduction without much extra burden, such as extra damping systems. High damping metallic materials that exhibit the ability to dissipate mechanical energy are potential candidates in these application via directly being part of the functional components, such as the frame materials. The energy damping in polycrystalline metals depends on the activities of defects such as dislocation and grain boundary. However, operating defects has the opposite effect on strength and damping capacity. In the quest for high damping metals, maintaining the level of strength More >

  • Open Access

    PROCEEDINGS

    Damping Influences on Instability Characteristics of Panel Aero-ThermoElastic System

    Xiaochen Wang1,*, Wei Tian2, Shengxi Zhou2, Peng Li1, Zhichun Yang2, Yiren Yang1

    The International Conference on Computational & Experimental Engineering and Sciences, Vol.26, No.1, pp. 1-1, 2023, DOI:10.32604/icces.2023.010582

    Abstract The complex damping influences on the instability characteristics of the panel aero-thermo-elastic system are theoretically investigated from the energy perspectives. Firstly, by assuming a constant, uniform thermal loading and adopting the piston theory, the panel aeroelastic governing equation is obtained. After deriving the panel buckling and vibration modes, the reduced order model can be built and adopted to investigate the system primary instability in the modal coordinates. Then, introducing the modal damping coefficients ratio η > 0, the critical parameters of the panel flutter oscillation are theoretically evaluated based on the on-conservative energy balance principle, thus More >

  • Open Access

    ARTICLE

    Parameter Design of Current Double Closed Loop for T-Type Three-Level Grid-Connected Inverter

    Tiankui Sun1,*, Mingming Shi1, Xiaolong Xiao1, Ping He1, Yu Ji1, Zhiyuan Yuan2

    Energy Engineering, Vol.120, No.7, pp. 1621-1636, 2023, DOI:10.32604/ee.2023.026948 - 04 May 2023

    Abstract To reduce current harmonics caused by switching frequency, T-type grid-connected inverter topology with LCL filter is adopted. In view of the disadvantages of the slow response speed of the traditional current control and the failure to eliminate the influence of the LCL filter on the grid-connected current by using current PI control alone, a current double closed loop PI current tracking control is proposed. Through the theoretical analysis of the grid-connected inverter control principle, the grid-connected inverter control model is designed, and the transfer function model of each control link is deduced, and the current More >

  • Open Access

    ARTICLE

    Experimental Investigation on the Effect of Seal Presence on the Behavior of Double-Deck Floating Roofs in Cylindrical Steel Storage Tanks

    Alireza Doustvandi, Mehrzad Tahamouli Roudsari*, Behnoush Niazi

    Structural Durability & Health Monitoring, Vol.17, No.1, pp. 55-70, 2023, DOI:10.32604/sdhm.2022.017458 - 02 March 2023

    Abstract Liquid storage, particularly oil and petrochemical products which are considered hazardous liquid, are an important part of the oil industry. Thin-walled vertical cylindrical steel storage tanks are widely used in recent years. Due to high sensitivity of these structures in an earthquake and other external excitations may lead to catastrophic consequences. For instance, huge economic losses, environmental damages, and casualities, many studies have been done about these structures. past studies showed that liquid storage tanks, equipped with a floating roof, are potentially vulnerable while subjected to seismic loads and earthquake has been considered as one… More >

  • Open Access

    ARTICLE

    Analysis of Additional Damping Control Strategy and Parameter Optimization for Improving Small Signal Stability of VSC-HVDC System

    Hui Fang1, Jingsen Zhou1, Hanjie Liu2,*, Yanxu Wang2, Hongji Xiang1, Yechun Xin2

    Energy Engineering, Vol.120, No.4, pp. 931-948, 2023, DOI:10.32604/ee.2023.025163 - 13 February 2023

    Abstract The voltage source converter based high voltage direct current (VSC-HVDC) system is based on voltage source converter, and its control system is more complex. Also affected by the fast control of power electronics, oscillation phenomenon in wide frequency domain may occur. To address the problem of small signal stability of the VSC-HVDC system, a converter control strategy is designed to improve its small signal stability, and the risk of system oscillation is reduced by attaching a damping controller and optimizing the control parameters. Based on the modeling of the VSC-HVDC system, the general architecture of… More >

  • Open Access

    ARTICLE

    Stability Analysis and Control of DC Distribution System with Electric Vehicles

    Zhijie Zheng1, Song Zhang1, Xiaolei Zhang2, Bo Yang1, Fang Yan3, Xiaoning Ge3,*

    Energy Engineering, Vol.120, No.3, pp. 633-647, 2023, DOI:10.32604/ee.2022.024081 - 03 January 2023

    Abstract The DC distribution network system equipped with a large number of power electronic equipment exhibits weak damping characteristics and is prone to low-frequency and high-frequency unstable oscillations. The current interpretation of the oscillation mechanism has not been unified. Firstly, this paper established the complete state-space model of the distribution system consisting of a large number of electric vehicles, characteristic equation of the distribution network system is derived by establishing a state-space model, and simplified reduced-order equations describing the low-frequency oscillation and the high-frequency oscillation are obtained. Secondly, based on eigenvalue analysis, the oscillation modes and More >

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