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 >

Meixian Li¹, Xin Hu¹, Jie Yang¹, Hongyu Yang^1,3,*, Yao Yuan^2,*

Journal of Renewable Materials, Vol.10, No.10, pp. 2639-2654, 2022, DOI:10.32604/jrm.2022.019491 - 08 June 2022

Abstract In this work, a bio-based flame retardant (Cy-HEDP) was synthesized from cytosine and HEDP through a facile salt-forming reaction and embedded into epoxy matrix to improve the flame retardancy and smoke suppression performance. The product Cy-HEDP was well characterized by FTIR, ¹ H and ³¹P NMR and SEM tests. On the basis of the results, by adding 15 wt% Cy-HEDP, the EP₁₅ can pass UL-94 V-0 rating, and the total smoke production (TSP) as well as total heat release (THR) can be decreased by 61.05% (from 22.61 to 8.7 m² /m² ) and 39.44% (from 103.19 to 62.50 More > Graphic Abstract

Pengfei Guan¹, Ping Li², Yiqiang Wu¹, Xingong Li¹, Guangming Yuan¹, Yingfeng Zuo^1,*

Journal of Renewable Materials, Vol.10, No.9, pp. 2451-2463, 2022, DOI:10.32604/jrm.2022.020459 - 30 May 2022

Abstract To enhance mechanical properties and improve flame retardancy and smoke suppression of fast-growing poplar wood in wood applications, the wood was impregnated and modified. An organic phenolic prepolymer and inorganic sodium silicate was used as contrasting impregnation modifiers and wood samples were impregnated by a bionic “respiration” method with alternating positive and negative pressure. The weight percentage gain, density increase ratio, mechanical properties (bending and compressive strength and hardness), and water absorption rate of inorganic and organic-impregnated modified poplar wood (IIMPW and OIMPW, respectively) were compared and these properties in IIMPW were found to be… More >

MASASHI KAWAMI^*, RYOKO YUMOTO, MIKIHISA TAKANO

BIOCELL, Vol.46, No.8, pp. 1861-1865, 2022, DOI:10.32604/biocell.2022.019667 - 22 April 2022

Abstract A number of drugs induce pulmonary injury and subsequently lead to serious lung diseases such as pulmonary fibrosis as the adverse drug reactions. However, an effective preventive approach against drug-induced pulmonary fibrosis has not been established due to poor understanding of common preventive targets in a variety of drugs showing pulmonary toxicity. Epithelial-mesenchymal transition (EMT), a cellular phenotypic change of the epithelial to mesenchymal state, contributes to the development of pulmonary fibrosis through the conversion of damaged alveolar epithelium into myofibroblasts. As several drugs with pulmonary toxicity have been reported to induce EMT, EMT serves… More >