Weiru Wang¹, Yulong Cao^1,*, Yanxu Wang¹, Jiale You¹, Guangnan Zhang¹, Yu Xiao²

Energy Engineering, Vol.121, No.12, pp. 3801-3823, 2024, DOI:10.32604/ee.2024.055398 - 22 November 2024

Abstract To ensure frequency stability in power systems with high wind penetration, the doubly-fed induction generator (DFIG) is often used with the frequency fast response control (FFRC) to participate in frequency response. However, a certain output power suppression amount (OPSA) is generated during frequency support, resulting in the frequency modulation (FM) capability of DFIG not being fully utilised, and the system’s unbalanced power will be increased during speed recovery, resulting in a second frequency drop (SFD) in the system. Firstly, the frequency response characteristics of the power system with DFIG containing FFRC are analysed. Then, based… More >

Haitao Liu^1,2,*, Jiaming Wang¹, Xiuliang Zhang¹, Yanji Jiang², Qian Xiao¹

CMES-Computer Modeling in Engineering & Sciences, Vol.139, No.3, pp. 2747-2772, 2024, DOI:10.32604/cmes.2024.047129 - 11 March 2024

Abstract The expansion chamber serves as the primary silencing structure within the exhaust pipeline. However, it can also act as a sound-emitting structure when subjected to airflow. This article presents a hybrid method for numerically simulating and analyzing the unsteady flow and aerodynamic noise in an expansion chamber under the influence of airflow. A fluid simulation model is established, utilizing the Large Eddy Simulation (LES) method to calculate the unsteady flow within the expansion chamber. The simulation results effectively capture the development and changes of the unsteady flow and vorticity inside the cavity, exhibiting a high… More > Graphic Abstract

LIPING YE^1,2,3,#, HUIYAN SUN^4,#, XINHUA LIANG^2,#, WENXU PAN², LI XIANG^2,3, WENJUN DU², LANLAN GENG², WANFU XU^2,3,*, SITANG GONG^1,2,3,*

BIOCELL, Vol.47, No.12, pp. 2709-2719, 2023, DOI:10.32604/biocell.2023.044295 - 27 December 2023

Abstract Introduction: Helicobacter pylori is a risk factor for the development of peptic ulcers with autophagy dysfunction. Omeprazole was widely known as the first-line regimen for H. pylori-associated gastritis. Objectives: The objective of this work was to assess the role of omeprazole on cell pyroptosis and autophagy. Methods: The clinical samples were collected. Quantitative polymerase chain reaction, western blotting, enzyme linked immunosorbent assay, and immunofluorescence (IF) analysis were conducted to reveal the mechanism of omeprazole on cell pyroptosis and autophagy. Results: The results revealed that omeprazole could decrease cell pyroptosis, which was attributed to the downregulation of cleaved caspase-1 expression,… More >

Kanhua Su, Jian Wei^*, Meng Li, Hao Li, Wenghao Da, Lang Zhang

Sound & Vibration, Vol.57, pp. 97-117, 2023, DOI:10.32604/sv.2023.043734 - 14 December 2023

Abstract During the drilling process, stick-slip vibration of the drill string is mainly caused by the nonlinear friction generated by the contact between the drill bit and the rock. To eliminate the fatigue wear of downhole drilling tools caused by stick-slip vibrations, the Fractional-Order Proportional-Integral-Derivative (FOPID) controller is used to suppress stick-slip vibrations in the drill string. Although the FOPID controller can effectively suppress the drill string stick-slip vibration, its structure is flexible and parameter setting is complicated, so it needs to use the corresponding machine learning algorithm for parameter optimization. Based on the principle of… More > Graphic Abstract

Chongyang Zhao, Wei Chai, Beibei Rui, Lin Chen^*

Energy Engineering, Vol.120, No.11, pp. 2683-2705, 2023, DOI:10.32604/ee.2023.029620 - 31 October 2023

Abstract At present, the direct drive permanent magnet synchronous generator (DD-PMSG) grid connected system based on virtual synchronous generator (VSG) control will experience power oscillation at sub synchronous frequencies. The mechanism and characteristics of this new type of sub-synchronous interaction (SSI) are not yet clear, and the system cannot recover to steady state solely based on the characteristics of VSG itself. Especially when connected to a weak current network, oscillations are more pronounced, affecting the stability of the system. In severe cases, the system may trigger shutdown protection and be disconnected from the network. Existing research More >

JIAN LI¹, QINGQING WANG², XIAOYING ZHANG^1,*

BIOCELL, Vol.47, No.6, pp. 1307-1316, 2023, DOI:10.32604/biocell.2023.028714 - 19 May 2023

Abstract Scutellarin (SCU) is a herbal flavonoid glucuronide with multiple pharmacological activities, including anti-oxidant, anti-inflammation, vascular relaxation, anti-platelet, and myocardial protection. However, the effect of SCU on complete Freund’s adjuvant (CFA)-induced rheumatoid arthritis (RA) had not been studied. In this study, we investigated the beneficial effects of SCU in the CFA-induced RA mice model and the anti-arthritic activity was evaluated by paw edema. Enzyme-linked immunosorbent assay (ELISA) was carried out to evaluate the plasma levels of immunoglobulin (Ig)G, IgE, tumor necrosis factor (TNF)-α, interleukin (IL)-1β, IL-6, receptor activator of nuclear factor-κB ligand (RANKL), and osteoprotegerin (OPG).… More >

Hui Fang¹, Jingsen Zhou¹, Haozheng Wang^2,*, Yanxu Wang², Hongji Xiang¹, Yechun Xin²

Energy Engineering, Vol.120, No.4, pp. 831-850, 2023, DOI:10.32604/ee.2023.025171 - 13 February 2023

Abstract Recently, high-frequency oscillation of the modular multilevel converter (MMC) based high-voltage direct current (HVDC) projects has attracted great attentions. In order to analyze the small-signal stability, this paper uses the harmonic state-space (HSS) method to establish a detailed frequency domain impedance model of the AC-side of the HVDC transmission system, which considers the internal dynamic characteristics. In addition, the suggested model is also used to assess the system's high-frequency oscillation mechanism, and the effects of the MMC current inner loop control, feedforward voltage links, and control delay on the high-frequency impedance characteristics and the effect More >

S. Girirajan, A. Pandian^*

Intelligent Automation & Soft Computing, Vol.35, No.2, pp. 1987-2001, 2023, DOI:10.32604/iasc.2023.028090 - 19 July 2022

Abstract Speech enhancement is the task of taking a noisy speech input and producing an enhanced speech output. In recent years, the need for speech enhancement has been increased due to challenges that occurred in various applications such as hearing aids, Automatic Speech Recognition (ASR), and mobile speech communication systems. Most of the Speech Enhancement research work has been carried out for English, Chinese, and other European languages. Only a few research works involve speech enhancement in Indian regional Languages. In this paper, we propose a two-fold architecture to perform speech enhancement for Tamil speech signal… More >

G. Karthiha^*, Dr. S. Allwin

Intelligent Automation & Soft Computing, Vol.35, No.2, pp. 1753-1765, 2023, DOI:10.32604/iasc.2023.022631 - 19 July 2022

Abstract In spite of the advancement in computerized imaging, many image modalities produce images with commotion influencing both the visual quality and upsetting quantitative image analysis. In this way, the research in the zone of image denoising is very dynamic. Among an extraordinary assortment of image restoration and denoising techniques the neural network system-based noise suppression is a basic and productive methodology. In this paper, Bilateral Filter (BF) based Modular Neural Networks (MNN) has been utilized for speckle noise suppression in the ultrasound image. Initial step the BF filter is used to filter the input image.… More >

Yongming Chen^1,2,#, Shuai Huang^1,#, Han Zhao¹, Ru Yang², Yining He¹, Tianyu Zhao¹, Yunlong Zhang¹, Qinghong Kong^1,*, Shasha Sun^3,*, Junhao Zhang³

Journal of Renewable Materials, Vol.10, No.12, pp. 3119-3130, 2022, DOI:10.32604/jrm.2022.019576 - 14 July 2022

Abstract To enhance the thermal stability and flame retardancy of epoxy resin (EP), beta-cyclodextrin (β-CD) is successfully introduced into the layered tin phenylphosphonate (SnPP), which is incorporated into EP matrix for preparing EP/β-CD@SnPP composites. The results indicate that the addition of β-CD@SnPP obviously improve the thermal stability and residual yield of EP composites at higher temperature. When the amount of β-CD@SnPP is only 4 wt%, EP/4β-CD@SnPP composites pass V-1 rating, and LOI value is up to 30.8%. Meanwhile, β- CD@SnPP effectively suppress the heat release and reduce the smoke production of EP/β-CD@SnPP composites in combustion, and More >