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A Novel Method to Suppress Mid-Frequency Vibrations with a High Speed-Loop Gain for PMSM Control
Li, Qiong,Xu, Qiang,Huang, Shenghua The Korean Institute of Power Electronics 2016 JOURNAL OF POWER ELECTRONICS Vol.16 No.3
PI controllers are one of the most widely used controllers in industrial control systems due to their simple algorithms and stability. The parameters K<sub>p</sub> and K<sub>i</sub> determine the performance of the system response. The response is expected to improve by increasing the gain of the PI controller. However, too large a gain will accelerate the speed response and cause vibrations, which is not what is expected. This paper proposes a way to suppress vibrations by detecting the vibration frequency and extracting the vibration signal as a compensation to the speed feedback. Additionally, in order to improve its disturbance rejection ability, a low-order disturbance observer is proposed. This paper also explains the operation principle of the proposed method by analyzing the transfer function and it describes the design of the controller parameters in detail. Simulation and experimental results are provided to verify the merits of the proposed method. These results also show the good performance of the proposed method. It has a rapid response and suppresses vibrations.
Shenghua Ding,Rongrong Wang,Jing Zhang,Gaoyang Li,Juhua Zhang,Shiyi Ou,Yang Shan 한국식품과학회 2017 Food Science and Biotechnology Vol.26 No.6
Changes in contents of sugars, organic acids, limonoids, phenolics contents, and antioxidant capacities of lemon slices dried at different temperatures were evaluated. Air drying (AD) promoted losses of sugars, citric acid, ascorbic acid, extractable phenolics (EPs), and nonextractable phenolics (NEPs), while it introduced an increase in limonoids. Phenolics of lemon were mainly presented in their extractable form. Hesperidin and eriocitrin were the main EPs; protocatechuic acid and poncirin were the predominant NEPs. The decrease in extractable phenolic acid, EP, and NEP content in lemon is lower at low drying temperatures, while the increase in non-extractable phenolic acid content is higher at high drying temperatures. The antioxidant capacity of EP was higher than that of NEP. Phenolics contributed to antioxidant capacities of lemon slices, and flavonoids were the main contributors among phenolics. Considering limonoids contents and the high levels of EP, NEP, and antioxidant capacities, AD at 60 C could be an appreciate treatment for dehydrating lemon slices.
A Novel Method to Suppress Mid-Frequency Vibrations with a High Speed-Loop Gain for PMSM Control
Qiong Li,Qiang Xu,Shenghua Huang 전력전자학회 2016 JOURNAL OF POWER ELECTRONICS Vol.16 No.3
PI controllers are one of the most widely used controllers in industrial control systems due to their simple algorithms and stability. The parameters Kp and Ki determine the performance of the system response. The response is expected to improve by increasing the gain of the PI controller. However, too large a gain will accelerate the speed response and cause vibrations, which is not what is expected. This paper proposes a way to suppress vibrations by detecting the vibration frequency and extracting the vibration signal as a compensation to the speed feedback. Additionally, in order to improve its disturbance rejection ability, a low-order disturbance observer is proposed. This paper also explains the operation principle of the proposed method by analyzing the transfer function and it describes the design of the controller parameters in detail. Simulation and experimental results are provided to verify the merits of the proposed method. These results also show the good performance of the proposed method. It has a rapid response and suppresses vibrations.
AFLP Molecular Markers Linked to the Pear Scab Resistance Gene
Xingguang Dong,Shenghua Lin,Fei Wang,Zhigang Wang,Li Fan,Chengquan Fang 한국원예학회 2010 Horticulture, Environment, and Biotechnology Vol.51 No.2
Pear scab (caused by Venturia nashicola) is one of the most harmful diseases in pear. Molecular markers closely linked to scab resistance genes will be greatly useful for improving pear breeding by marker-assisted selection. In our study, a F₁ population (139 individuals) from the cross ‘Huangguan’ (Resistance) and ‘Yali’ (Susceptible) was analyzed, and bulked segregant analysis (BSA) was conducted to find AFLP fragments linked to the locus of scab resistance in pear. Out of 64 fluorescent AFLP primers, two markers showed polymorphisms between the resistant-bulk and the susceptible-bulk, as well as between the parents. D3-365 were found linked to the resistance locus. By using selective genotype analysis, the genetic distances between the marker and the resistant locus were 14.9cM.
Zhiqiang Ren,Shenghua He,Jiao Li,Yeguang Wang,Juyi Lai,Zhitao Sun,Hualong Feng,Jian Wang 대한척추신경외과학회 2020 Neurospine Vol.17 No.1
Objective: To assess the safety and effectiveness of percutaneous endoscopic lumbar discectomy (PELD) under epidural anesthesia (EA) and general anesthesia (GA) for treating lumbar disc herniation (LDH). Methods: A retrospective study involving 86 patients with LDH managed by PELD under EA and GA was conducted from July 2018 to March 2019. These patients were divided into 2 groups according to the type of anesthesia. Patient’s demographics data as well as the operation time, complications, fluoroscopy shots, visual analog scale (VAS), Oswestry Disability Index (ODI), Japanese Orthopaedic Association (JOA), and MacNab scores of the 2 groups were recorded. All of the patients were followed-up at 6 months after operation. Results: There were no significant differences were detected in the preoperative demographics between the groups (p>0.05). Two cases (4.8%) under GA developed transient motor weakness, 3 cases (7.4%) presented numbness of lower limb, and 1 case (2.4%) had cauda equina syndrome after operation. In EA group, 1 case (2.2%) had motor weakness and 3 cases (6.7%) had lower limb numbness, which resolved completely at the last follow-up. There was significant difference between preoperative VAS, JOA, and ODI scores and postoperative scores (p<0.01). Moreover, there were no differences in the operation time, fluoroscopy shots, and MacNab scores between the 2 groups (p>0.05). Conclusion: EA and GA in PELD are effective and safe, and no significant difference in complications was observed. Based on our experience, we recommended junior surgeons to perform PELD under EA for getting feedback from the patient to avoid nerve injury and reduce the radiation dose. The concentration of ropivacaine in EA should be considered carefully.
Jin, Yuansheng,Li, Shenghua,Peng, Haitao ENGINEERING TRIBOLOGY RESEARCH INSTITUTE KYUNGPOOK 1999 INTERNATIONAL SYMPOSIUM ON HIGH PERFORMANCE OF TRI Vol.1999 No.-
The investigations on tribological and quality evaluations of coatings and thin films which have been done over recent years in National Tribology Laboratory, Tsinghua University, were summarized. The main contents of the present overview include tribological evaluations of thermally sprayed ceramic and metallic coatings, tribological behaviors and mechanisms of coatings designed for high temperature lubrication and mechanisms of coatings designed for figh temperature lubrication, and quality evaluation of ceramic coatings and thin films by ultrasonics and micro-indentation.
Xi Chen,Shenghua Huang,Dong Jiang,Bingzhang Li 대한전기학회 2018 Journal of Electrical Engineering & Technology Vol.13 No.5
In this paper, a novel neutral-point voltage balancing scheme for NPC three-level inverters using carrier-based sinusoidal pulse width modulation (SPWM) method is developed. The new modulation approach, based on the obtained expressions of zero sequence voltage in all six sectors, can significantly suppress the low-frequency voltage oscillation in the neutral point at high modulation index and achieve a fast voltage-balancing dynamic performance. The implementation of the proposed method is very simple. Another attractive feature is that the scheme can stably control any voltage difference between the two dc-link capacitors within a certain range without using any extra hardware. Furthermore, the presented scheme is also applicable to the single-phase NPC threelevel inverter. It can maintain the neutral-point voltage balance at full modulation index and improve the voltage-balancing dynamic performance of the single-phase NPC three-level inverter. The performance of the proposed strategy and its benefits over other previous techniques are verified experimentally.
Deposition and evaluation of MoNx films deposited by magnetron sputtering
Yajun Ma,Shenghua Li,Yuansheng Jin,Guoshun Pan,Yucong Wang,Simon C. Tung 한국트라이볼로지학회 2002 한국트라이볼로지학회 학술대회 Vol.2002 No.10
Molybdenum Nitrided (MoNx) films were deposited by DC planar magnetron sputtering. Silicon wafers and real nitrided stainless steel piston rings are employed as substrates. 12 different combinations of nitrogen and argon partial pressure, from 1:7 to 7:1, were applied to deposit MoNx films. X-ray diffraction (XRD) was used to determine the phase structures of films. When nitrogen vs. argon partial pressure is 1:7, the film is mainly MO₂N phase. With increase of nitrogen partial pressure, MoN phase emerges, but MO₂N phase still exists. Composition analysis with atomic emission spectrometry (AES) also agreed with this. The films have very high nanohardness (max 2400Hv) and good adhesion to the substrates.
Chen, Xi,Huang, Shenghua,Jiang, Dong,Li, Bingzhang The Korean Institute of Electrical Engineers 2018 Journal of Electrical Engineering & Technology Vol.13 No.5
In this paper, a novel neutral-point voltage balancing scheme for NPC three-level inverters using carrier-based sinusoidal pulse width modulation (SPWM) method is developed. The new modulation approach, based on the obtained expressions of zero sequence voltage in all six sectors, can significantly suppress the low-frequency voltage oscillation in the neutral point at high modulation index and achieve a fast voltage-balancing dynamic performance. The implementation of the proposed method is very simple. Another attractive feature is that the scheme can stably control any voltage difference between the two dc-link capacitors within a certain range without using any extra hardware. Furthermore, the presented scheme is also applicable to the single-phase NPC three-level inverter. It can maintain the neutral-point voltage balance at full modulation index and improve the voltage-balancing dynamic performance of the single-phase NPC three-level inverter. The performance of the proposed strategy and its benefits over other previous techniques are verified experimentally.