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  • 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



    Ali Chitsazana , Georg Kleppa, Mohammad Esmaeil Chitsazanb, Birgit Glasmacherc

    Frontiers in Heat and Mass Transfer, Vol.18, pp. 1-6, 2022, DOI:10.5098/hmt.18.17

    Abstract For the optimization of the impinging round jet, the pressure force coefficient and drying energy consumption on the moving curved surface are set as the objective functions to be minimized simultaneously. SHERPA search algorithm is used to search for the optimal point from multiple objective tradeoff study (Pareto Front) method. It is found that the pressure force coefficient on the impingement surface is highly dependent on the jet to surface distance and jet angle, while the drying energy consumption is highly dependent on the jet to jet spacing. Generally, the best design study during the multi-objective optimization is found at… More >

  • Open Access



    Ali Chitsazana, Georg Kleppa, Birgit Glasmacherb

    Frontiers in Heat and Mass Transfer, Vol.18, pp. 1-9, 2022, DOI:10.5098/hmt.18.16

    Abstract The effect of jet Reynolds number, jet exit angle, the nozzle to surface distance, jet to jet spacing on the heat transfer, and pressure force performance from multiple impinging round jets on a moving curved surface have been numerically evaluated. Two correlations are developed and validated for the average Nu number and the pressure force coefficient and the agreement between the CFD and correlations was reasonable. The surface motion effect becomes more pronounced on the Nu number distribution for low jet Re number, high jet to jet spacing, large jet to surface distance, and angled jets. The pressure force coefficient… More >

  • Open Access



    Ali Chitsazana , Georg Kleppa, Birgit Glasmacherb

    Frontiers in Heat and Mass Transfer, Vol.18, pp. 1-7, 2022, DOI:10.5098/hmt.18.15

    Abstract The effect of surface curvature, number of jets, number of jet rows, jet arrangement, crossflow, and surface motion on the heat transfer and pressure force performance from multiple impinging round jets on the moving flat and curved surface have been numerically evaluated. The more number of jets (more than three jets) has no significant effect on the average heat transfer rate. The more number of jet rows increases the strength of wall jets interference and crossflow effects and degrade the average heat transfer rates. There is a minor difference between inline and staggered arrangements on both moving flat and curved… More >

  • Open Access



    Ali Chitsazana,*, Georg Kleppa, Birgit Glasmacherb

    Frontiers in Heat and Mass Transfer, Vol.19, pp. 1-8, 2022, DOI:10.5098/hmt.19.35

    Abstract The objective of the present research is the prediction of large arrays of impingement jets using a computational model. The heat transfer and the force coefficient from single and multiple jet rows (1, 2, 4, 8, and infinity rows) for two different nozzle shapes as either orifice or straight pipe on a fixed flat surface were numerically investigated for drying applications to understand the physical mechanisms which affect the uniformity of the local heat transfer and pressure force coefficient as well as average heat transfer coefficient. The pipe has always a higher averaged Nu and pressure force coefficient compared to… 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


    Volunteering and Depression among Older Adults: An Empirical Analysis Based on CLASS 2018

    Zhendong Wu1, Chen Xu2, Liyan Zhang3, Yang Wang4, George W. Leeson5, Gong Chen4,*, Julien S. Baker6, Xiao-Guang Yue7,8

    International Journal of Mental Health Promotion, Vol.25, No.3, pp. 403-419, 2023, DOI:10.32604/ijmhp.2023.024638

    Abstract Introduction:: Older adults are prone to high levels of depression due to their deteriorating physical functions and shrinking social networks after retirement. Volunteering as an important social activity is essential for alleviating depression by building social network. This paper aims to examine the effect of volunteering on depression among older adults by using China Longitudinal Aging Social Survey (CLASS 2018) data.Methods:: This study uses descriptive analysis and chi-square tests to show differences in demographic factors of older adults’ volunteerism participation, followed by bivariate correlation analysis to examine the correlation between the vital variables. Afterward, stratified linear regression analysis is used… More >

  • Open Access


    Extraction of Strain Characteristic Signals from Wind Turbine Blades Based on EEMD-WT

    Jin Wang1, Zhen Liu1,*, Ying Wang1, Caifeng Wen2,3, Jianwen Wang2,3

    Energy Engineering, Vol.120, No.5, pp. 1149-1162, 2023, DOI:10.32604/ee.2023.025209

    Abstract Analyzing the strain signal of wind turbine blade is the key to studying the load of wind turbine blade, so as to ensure the safe and stable operation of wind turbine in natural environment. The strain signal of the wind turbine blade under continuous crosswind state has typical non-stationary and unsteady characteristics. The strain signal contains a lot of noise, which makes the analysis error. Therefore, it is very important to denoise and extract features of measured signals before signal analysis. In this paper, the joint algorithm of ensemble empirical mode decomposition (EEMD) and wavelet transform (WT) is used for… 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


    Constructing an AI Compiler for ARM Cortex-M Devices

    Rong-Guey Chang, Tam-Van Hoang*

    Computer Systems Science and Engineering, Vol.46, No.1, pp. 999-1019, 2023, DOI:10.32604/csse.2023.034672

    Abstract The diversity of software and hardware forces programmers to spend a great deal of time optimizing their source code, which often requires specific treatment for each platform. The problem becomes critical on embedded devices, where computational and memory resources are strictly constrained. Compilers play an essential role in deploying source code on a target device through the backend. In this work, a novel backend for the Open Neural Network Compiler (ONNC) is proposed, which exploits machine learning to optimize code for the ARM Cortex-M device. The backend requires minimal changes to Open Neural Network Exchange (ONNX) models. Several novel optimization… More >

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