Robust Time Delay Compensation for DTC-Based Induction Machine Systems via Extended State Observers

Fengxiang Wang,Junxiao Wang,Li Yu 전력전자학회 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.3

This paper presents an extended state observer (ESO) based direct torque control (DTC) for use in induction motor systems to handle the issues of time delays, load torque disturbances and parameter uncertainties. Direct torque control offers an excellent torque response and it does not require a proportion integration (PI) controller in the current loop. However, a PI controller is still adopted in the outer speed loop to generate the torque reference value, which is a slow method. An ESO based compound control scheme is proposed to improve the response rate and accuracy of the torque reference signal, especially when load torque is injected. In addition, the time delay problem is analyzed and compensated for in this paper to reduce torque ripples. The proposed disturbance compensation technique based direct control scheme is shown to have good performance both in the transient and stable states via simulations and experimental results.

Preparation of high surface area carborundum-supported cobalt catalysts for hydrogen production by ammonia decomposition

Li Guoru,Tan Yuhang,Lei Zhiping,Yin Fengxiang,He Xiaobo 한국탄소학회 2023 Carbon Letters Vol.33 No.3

Ammonia is a potential fuel for producing and storing hydrogen, but its usage is constrained by the high cost of the noble metal catalysts to decompose NH3. Utilizing non-precious catalysts to decompose ammonia increases its potential for hydrogen production. In this study, carborundum (SiC)-supported cobalt catalysts were prepared by impregnating Co3O4 nanoparticles (NPs) on SiC support. The catalysts were characterized by high-resolution transmission electron microscope, X-ray photoelectron spectroscopy, temperature programmed reduction, etc. The results show that the large specific surface area of SiC can introduce highly distributed Co3O4 NPs onto the surface. The amount of Co in the catalysts has a significant effect on the catalyst structure, particle size and catalytic performances. Due to the interaction of cobalt species with SiC, the 25Co/SiC catalyst provided the optimal ammonia conversion of 73.2% with a space velocity of 30,000 mL gcat−1 h−1 at 550 °C, corresponding to the hydrogen production rate of 24.6 mmol H2 gcat−1 min−1. This research presents an opportunity to develop highly active and cost-effective catalysts for hydrogen production via NH3 decomposition.

A Dual Functional Ti-Ga Alloy: Inhibiting Biofilm Formation and Osteoclastogenesis Differentiation via Disturbing Iron Metabolism

Fupeng Li,Kai Huang,Jinbing Wang,Kai Yuan,Yiqi Yang,Yihao Liu,Xianhao Zhou,Keyu Kong,Tao Yang,Jian He,Chunjie Liu,Haiyong Ao,Fengxiang Liu,Qian Liu,Tingting Tang,Shengbing Yang 한국생체재료학회 2023 생체재료학회지 Vol.27 No.00

Background Although biomedical implants have been widely used in orthopedic treatments, two major clinical challenges remain to be solved, one is the bacterial infection resulting in biofilm formation, and the other is aseptic loosening during implantation due to over-activated osteoclastogenesis. These factors can cause many clinical issues and even lead to implant failure. Thus, it is necessary to endow implants with antibiofilm and aseptic looseningprevention properties, to facilitate the integration between implants and bone tissues for successful implantation. To achieve this goal, this study aimed to develop a biocompatible titanium alloy with antibiofilm and anti-aseptic loosening dual function by utilizing gallium (Ga) as a component. Methods A series of Ti-Ga alloys were prepared. We examined the Ga content, Ga distribution, hardness, tensile strength, biocompatibility, and anti-biofilm performance in vitro and in vivo. We also explored how Ga3+ ions inhibited the biofilm formation of Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) and osteoclast differentiation. Results The alloy exhibited outstanding antibiofilm properties against both S. aureus and E. coli in vitro and decent antibiofilm performance against S. aureus in vivo. The proteomics results demonstrated that Ga3+ ions could disturb the bacterial Fe metabolism of both S. aureus and E. coli, inhibiting bacterial biofilm formation. In addition, Ti-Ga alloys could inhibit receptor activator of nuclear factor-κB ligand (RANKL)-dependent osteoclast differentiation and function by targeting iron metabolism, then suppressing the activation of the NF-κB signaling pathway, thus, showing their potential to prevent aseptic loosening. Conclusion This study provides an advanced Ti-Ga alloy that can be used as a promising orthopedic implant raw material for various clinical scenarios. This work also revealed that iron metabolism is the common target of Ga3+ ions to inhibit biofilm formation and osteoclast differentiation.

Robust Time Delay Compensation for DTC-Based Induction Machine Systems via Extended State Observers

Wang, Fengxiang,Wang, Junxiao,Yu, Li The Korean Institute of Power Electronics 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.3

This paper presents an extended state observer (ESO) based direct torque control (DTC) for use in induction motor systems to handle the issues of time delays, load torque disturbances and parameter uncertainties. Direct torque control offers an excellent torque response and it does not require a proportion integration (PI) controller in the current loop. However, a PI controller is still adopted in the outer speed loop to generate the torque reference value, which is a slow method. An ESO based compound control scheme is proposed to improve the response rate and accuracy of the torque reference signal, especially when load torque is injected. In addition, the time delay problem is analyzed and compensated for in this paper to reduce torque ripples. The proposed disturbance compensation technique based direct control scheme is shown to have good performance both in the transient and stable states via simulations and experimental results.

Game Analysis on External Purchase of Technology Innovation under Complete Information

Zhang Guoliang,Li Fengxiang 한국멀티미디어학회 2010 한국멀티미디어학회 국제학술대회 Vol.2010 No.-

In fierce market competition, technological innovation becomes a crucial element which effects the sustainable development of enterprises. Nowadays external purchase of innovative technology is important and is essentially the results of the game between enterprise and innovative research institutions. The two players in the game analyze counterpart's policy to choose the best strategy to achieve the greatest benefits.

Ionic liquid/ZIF-67 derived Co9S8-SNC catalyst for oxygen reduction reaction in alkaline electrolyte

Gao Qiuyue,Li Guoru,Kofie Gideon,Chen Biaohua,Yin Fengxiang 한국탄소학회 2024 Carbon Letters Vol.34 No.3

A series of ZIF-67-C-IL catalysts were prepared using ZIF-67 and 1-butyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide ([BMIM]NTf2) ionic liquid as precursors. The structure of the catalysts was characterized by XRD, TEM, SEM and XPS. The catalytic performance of the catalysts for the oxygen reduction reaction (ORR) was evaluated in a three-electrode system. The results confirmed that the high-temperature treatment of the precursors resulted in the formation of N, S co-doped carbon-encapsulated Co9S8 nanoparticles. To create N, S co-doped carbon coated Co9S8 nanoparticle catalysts, ionic liquids are used as sulfur and nitrogen sources. The catalytic activity of ORR can be improved using N, S co-doped carbon to prevent the aggregation of Co9S8 nanoparticles. Graphitized and N, S co-doped carbon shells are optimal for achieving high activity stability. Optimal 600-ZIF-67-C(1:1.5)-30IL catalytic activity was observed for ORR. The half-wave potential of ORR was 0.88 V vs. RHE in 0.1 mol L−1 KOH, with a limit current density of 4.70 mA cm−2. Similar ORR electrocatalytic activity was observed between this catalyst and commercial Pt/C (20 wt%).

Measurement of Intra-Fraction Displacement of the Mediastinal Metastatic Lymph Nodes Using Four-Dimensional CT in Non-Small Cell Lung Cancer

Suzhen Wang,Jianbin Li,Yingjie Zhang,Wei Wang,Fengxiang Li,Tingyong Fan,Min Xu,Qian Shao 대한영상의학회 2012 Korean Journal of Radiology Vol.13 No.4

Objective: To measure the intra-fraction displacements of the mediastinal metastatic lymph nodes by using four-dimensional CT (4D-CT) in non-small cell lung cancer (NSCLC). Materials and Methods: Twenty-four patients with NSCLC, who were to be treated by using three dimensional conformal radiation therapy (3D-CRT), underwent a 4D-CT simulation during free breathing. The mediastinal metastatic lymph nodes were delineated on the CT images of 10 phases of the breath cycle. The lymph nodes were grouped as the upper, middle and lower mediastinal groups depending on the mediastinal regions. The displacements of the center of the lymph node in the left-right (LR), anterior-posterior (AP), and superior-inferior (SI) directions were measured. Results: The mean displacements of the center of the mediastinal lymph node in the LR, AP, and SI directions were 2.24 mm, 1.87 mm, and 3.28 mm, respectively. There were statistically significant differences between the displacements in the SI and LR, and the SI and AP directions (p < 0.05). For the middle and lower mediastinal lymph nodes, the displacement difference between the AP and SI was statistically significant (p = 0.005; p = 0.015), while there was no significant difference between the LR and AP directions (p < 0.05). Conclusion: The metastatic mediastinal lymph node movements are different in the LR, AP, and SI directions in patients with NSCLC, particularly for the middle and lower mediastinal lymph nodes. The spatial non-uniform margins should be considered for the metastatic mediastinal lymph nodes in involved-field radiotherapy. Objective: To measure the intra-fraction displacements of the mediastinal metastatic lymph nodes by using four-dimensional CT (4D-CT) in non-small cell lung cancer (NSCLC). Materials and Methods: Twenty-four patients with NSCLC, who were to be treated by using three dimensional conformal radiation therapy (3D-CRT), underwent a 4D-CT simulation during free breathing. The mediastinal metastatic lymph nodes were delineated on the CT images of 10 phases of the breath cycle. The lymph nodes were grouped as the upper, middle and lower mediastinal groups depending on the mediastinal regions. The displacements of the center of the lymph node in the left-right (LR), anterior-posterior (AP), and superior-inferior (SI) directions were measured. Results: The mean displacements of the center of the mediastinal lymph node in the LR, AP, and SI directions were 2.24 mm, 1.87 mm, and 3.28 mm, respectively. There were statistically significant differences between the displacements in the SI and LR, and the SI and AP directions (p < 0.05). For the middle and lower mediastinal lymph nodes, the displacement difference between the AP and SI was statistically significant (p = 0.005; p = 0.015), while there was no significant difference between the LR and AP directions (p < 0.05). Conclusion: The metastatic mediastinal lymph node movements are different in the LR, AP, and SI directions in patients with NSCLC, particularly for the middle and lower mediastinal lymph nodes. The spatial non-uniform margins should be considered for the metastatic mediastinal lymph nodes in involved-field radiotherapy.

Fluorometric determination of Fe3+ and polychlorinated benzenes based on Tb3+-pyromellitic acid coordination polymer

Linli Hou,Yonghai Song,Fengxiang Lang,Zhenrong Wang,Li Wang 한국공업화학회 2020 Journal of Industrial and Engineering Chemistry Vol.90 No.-

A luminescent Tb3+-pyromellitic acid (H4L = pyromellitic acid) coordination polymer (Tb-H4L CP, TbL0.5(H2L)0.5(H2O)DMF) was prepared for multiresponsive fluorescence sensor. The Tb-H4L CP exhibits uniform nanospheres with average diameter of 220 20 nm, good crystalline structure, and good dispersion in water. The Tb-H4L CP emitted the characteristic green fluorescence through antenna effect from H4L which was an excellent antenna molecule when excited at 270 nm and could be used to selectively determine Fe3+ and polychlorinated benzenes based on fluorescence quenching effect. The coordination between Fe3+ and carboxylic oxygen of Tb-H4L to damage the antenna effect and polychlorinated benzenes absorb the excitation light to result the inner-filter effect of fluorescence, which quenched the fluorescence of Tb-H4L CP. The linear range for Fe3+ was 2.0–100mM with a detection limit of 0.7mM and for 1,3,5-trichlorobenzene was 0–0.44 103 ppm with a detection limit of 0.087 ppm. The Tb-H4L CP demonstrates excellent fluorescence sensing performances, indicating that it can be used as a multi-response sensor to effectively measure toxic and harmful substances.