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  • Open Access


    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 the system instability characteristics… More >

  • Open Access


    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

    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 loop PI regulator is designed… More >

  • Open Access


    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

    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 of the most destructive natural… More >

  • Open Access


    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

    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 the inner and outer loop… More >

  • Open Access


    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

    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 the influence of the key… More >

  • Open Access


    Computation of Stiffness and Damping Derivatives of an Ogive in a Limiting Case of Mach Number and Specific Heat Ratio

    Aysha Shabana1,2,*, Asha Crasta1, Sher Afghan Khan3, Abdul Aabid4, Muneer Baig4

    FDMP-Fluid Dynamics & Materials Processing, Vol.19, No.5, pp. 1249-1267, 2023, DOI:10.32604/fdmp.2023.023158

    Abstract This work aims to compute stability derivatives in the Newtonian limit in pitch when the Mach number tends to infinity. In such conditions, these stability derivatives depend on the Ogive’s shape and not the Mach number. Generally, the Mach number independence principle becomes effective from M = 10 and above. The Ogive nose is obtained through a circular arc on the cone surface. Accordingly, the following arc slopes are considered λ = 5, 10, 15, −5, −10, and −15. It is found that the stability derivatives decrease due to the growth in λ from 5 to 15 and vice versa.… More >

  • Open Access


    Research on VSG Frequency Characteristics and Energy Storage Device Capacity and Charge-Discharge Characteristics Based on Feedforward Branch

    Baoge Zhang1, Shanyan Ping1,*, Haoliang Shi2, Yi Long1, Boxiang Wu1, Yuemin Jiao1

    Energy Engineering, Vol.119, No.6, pp. 2347-2367, 2022, DOI:10.32604/ee.2022.021693

    Abstract Renewable energy is connected to the grid through the inverter, which in turn reduces the inertia and stability of the power grid itself. The traditional grid-connected inverter does not have the function of voltage regulation and frequency regulation and can therefore no longer adapt to the new development. The virtual synchronous generator (VSG) has the function of voltage regulation and frequency regulation, which has more prominent advantages than traditional inverters. Based on the principle of VSG, the relationship between the frequency characteristics and the energy storage capacity of the feedforward branch-based virtual synchronous machine (FVSG) is derived when the input… More >

  • Open Access


    On the Dynamics of a Viscoelastic Fluid-Conveying Nanotube

    Ola Adil Ibrahim1, Gunawan Widjaja2, Abdulhussien N. Alattabi3, Krishanveer Singh4, Yasser Fakri Mustafa5, P. A. Krovopuskov6, Mustafa M. Kadhim7,*

    FDMP-Fluid Dynamics & Materials Processing, Vol.18, No.4, pp. 1137-1151, 2022, DOI:10.32604/fdmp.2022.019921

    Abstract The objective of the presented study is to perform a vibration analysis and investigate the stability of a viscoelastic-fluid conveying pipe with an intermediate support. The mathematical model is elaborated in the framework of the Euler-Bernoulli beam theory in combination with the Kelvin-Voight viscoelastic approach. The resulting differential equation of motion and the related boundary conditions and compatibility conditions in the mid-span support are solved analytically using a power series method. The results show that an intermediate support located at ξs = 0.1 and ξs = 0.5 increases the critical velocity up to 35% and 50.15%, respectively. Also, the non-dimensional… More >

  • Open Access


    Corrected Statistical Energy Analysis Model in a Non-Reverberant Acoustic Space

    Al Munawir1, Azma Putra2,*, Iwan Prasetiyo3, Wan Mohd Farid Wan Mohamad2, Safarudin Herawan4

    Sound & Vibration, Vol.55, No.3, pp. 203-219, 2021, DOI:10.32604/sv.2021.015938

    Abstract Statistical Energy Analysis (SEA) is a well-known method to analyze the flow of acoustic and vibration energy in a complex structure. This study investigates the application of the corrected SEA model in a non-reverberant acoustic space where the direct field component from the sound source dominates the total sound field rather than a diffuse field in a reverberant space which the classical SEA model assumption is based on. A corrected SEA model is proposed where the direct field component in the energy is removed and the power injected in the subsystem considers only the remaining power after the loss at… More >

  • Open Access


    Experimental Modal Damping Identification of a Mechanical Structure Using Video Magnification Technique

    Jaafar Hallal1,*, Mahmoud Fakih2, Hala Damerji3, Mohammad Hammoud4,5, Mehdi Chouman4,5

    Sound & Vibration, Vol.55, No.2, pp. 131-140, 2021, DOI:10.32604/sv.2021.015293

    Abstract Vibration can be introduced in all mechanical fields in our life. Engineers try to avoid its negative effect leading in some cases to deformation in the machines. Many researches are dedicated to study the identification of damping especially in multi degree of freedom systems with particular attention to the source of energy dissipation. They focus on developing new tools or methods which may be used in real problems to obtain accurate results about the amount (or value) and the location of energy dissipation in the structure. The aim of this paper is to present an original procedure aims to experimentally… More >

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