Non-Cascade Fast Nonsingular Terminal Sliding Mode Control of Permanent Magnet Synchronous Motor Based on Disturbance Observers

Li Tong,Liu Xudong 대한전기학회 2022 Journal of Electrical Engineering & Technology Vol.17 No.2

This paper proposes a new non-cascade fast nonsingular terminal sliding mode control algorithm based on disturbance observers for the speed control of permanent magnet synchronous motor (PMSM). To ensure the high precision control and fast fi nite-time convergence, a fast nonsingular terminal sliding mode controller is designed for PMSM. The novel controller adopts the single-loop non-cascade control structure. Then, to improve the anti-disturbance ability, a nonlinear disturbance observer and a dual disturbance observer are respectively designed to estimate the disturbances during motor operation, which are used for the feed-forward compensation control. The composite control method can eff ectively alleviate the larger chattering caused by the high sliding mode gain. Finally, the stability is proved based on Lyapunov stability theory. Simulation and experimental results show that the proposed method has the advantages of fast convergence and strong robustness against parameter variations and external disturbances.

Evaluation of the effects of different freezing and thawing methods on the quality preservation of Pleurotus eryngii

Li, Tong,Lee, Jo-Won,Luo, Li,Kim, Jongkee,Moon, BoKyung The Korean Society for Applied Biological Chemistr 2018 Applied Biological Chemistry (Appl Biol Chem) Vol.61 No.3

The individually quick-frozen (IQF) method is used to produce high-quality frozen food by freezing an individual piece of food separately from the remaining food. In this study, the effect of various freezing and thawing combinations on the quality preservation of Pleurotus eryngii (king oyster mushroom) was investigated. For this purpose, diced and mini P. eryngii mushrooms were frozen by natural freezing (NF, $-20^{\circ}C$) or IQF ($-62.5^{\circ}C$ and speed 8.23 m/s) methods and thawed using three thawing methods-flowing water thawing (FT, $4^{\circ}C$), microwave thawing (MT, 620 W), or natural air convection thawing (NT, $20{\pm}5^{\circ}C$). Quality characteristics, such as thawing loss, texture, water holding capacity, color, microstructure, and sensory quality, were evaluated. MT showed the most rapid thawing time, followed by FT and NT for all the samples. The results showed that thawing curve, water holding capacity, and hardness of IQF samples were better than those of NF samples after NT, FT, and MT. Scanning electron microscopy analysis revealed that cell integrity of the IQF sample was better than that of the NF sample. MT is the fastest of the thawing methods, but thawing after NF yielded a sample closest to the fresh mushroom sample. Therefore, when combined with NT, IQF minimized the quality changes in frozen diced and mini P. eryngii mushrooms. This study showed that the IQF technology can be used as a new preservation and distribution method of mushroom.

Predicting Pathological Complete Response in Breast Cancer After Two Cycles of Neoadjuvant Chemotherapy by Tumor Reduction Rate: A Retrospective Case-Control Study

Litong Yao,Xiaoyan Liu,Mozhi Wang,Keda Yu,Shouping Xu,Pengfei Qiu,Zhidong Lv,Xinwen Zhang,Yingying Xu 한국유방암학회 2023 Journal of breast cancer Vol.26 No.2

Purpose: We aimed to identify effectiveness-associated indicators and evaluate the optimal tumor reduction rate (TRR) after two cycles of neoadjuvant chemotherapy (NAC) in patients with invasive breast cancer. Methods: This retrospective case-control study included patients who underwent at least four cycles of NAC at the Department of Breast Surgery between February 2013 and February 2020. A regression nomogram model for predicting pathological responses was constructed based on potential indicators. Results: A total of 784 patients were included, of whom 170 (21.68%) reported pathological complete response (pCR) after NAC and 614 (78.32%) had residual invasive tumors. The clinical T stage, clinical N stage, molecular subtype, and TRR were identified as independent predictors of pCR. Patients with a TRR > 35% were more likely to achieve pCR (odds ratio, 5.396; 95% confidence interval [CI], 3.299–8.825). The receiver operating characteristic (ROC) curve was plotted using the probability value, and the area under the ROC curve was 0.892 (95% CI, 0.863–0.922). Conclusion: TRR > 35% is predictive of pCR after two cycles of NAC, and an early evaluation model using a nomogram based on five indicators, age, clinical T stage, clinical N stage, molecular subtype, and TRR, is applicable in patients with invasive breast cancer.

Fundamental issues of applications of C/SiC composites for re-entry vehicles

Yani Zhang,Litong Zhang,Hui Mei,Qingqing Ke,Yongdong Xu,Laifei Cheng 한양대학교 세라믹연구소 2009 Journal of Ceramic Processing Research Vol.10 No.3

Carbon fiber reinforced silicon carbide ceramic matrix composite materials (C/SiCs) are being tested for hot structures and thermal protection systems (TPS) of launch vehicles and spacecraft, and also for advanced friction system of aircraft and racing cars. A number of tribological and joining components are required in these applications, such as bushing and rolling contact bearings, nuts and bolts, which require excellent mechanical, physical and chemical properties at temperatures higher than 1650℃. This study summarizes preparation of C/SiC load-carrying bearings for hinge by the Chemical Vapor Infiltration (CVI) method and C/SiC bolts for joints by the CVI + PIP (Polymer Impregnation and Pyrolysis) methods. The hinge bearing and bolts were examined in a simulated re-entry environment. Stress-oxidation was investigated under different stress levels from 0 to 200MPa up to 1800℃. The friction behavior of the hinge bearing system was studied under high loads (up to 25 kN) and low rotating velocities. The mechanical properties of the bolts with a thread connection were conducted under tensile and shear fatigue at both room temperature and elevated temperature. The results show that the stress-oxidation behavior of 2D-C/SiC composites in a combustion environment is a combined effect of extremely high load, high temperature, and oxidation. The load and temperature influenced the crack openings and thus the oxidation of carbon fibers in the precracked composites. The combustion environment mainly determined the time to failure of the specimens by oxidation damage under a high applied stress. Reliable thermal load-carrying ability and stable friction performance of the hinge bearing is demonstrated in high-temperature combustion environments with extremely high loads. The oxidation products of SiO2 at high temperatures between surfaces played an important role to modifies the friction by providing a protective layer. The room temperature tensile and shear strength of the bolts made of needled C/SiC are 139 MPa and 83 MPa, respectively. Even at 1800℃ in a combustion environment, the strengths still retained about 116MPa with a maximum decrease of 13%. More importantly, the bolts did not suffer significant mechanical degradation after tension-tension fatigue at 1 Hz for 24 h. Carbon fiber reinforced silicon carbide ceramic matrix composite materials (C/SiCs) are being tested for hot structures and thermal protection systems (TPS) of launch vehicles and spacecraft, and also for advanced friction system of aircraft and racing cars. A number of tribological and joining components are required in these applications, such as bushing and rolling contact bearings, nuts and bolts, which require excellent mechanical, physical and chemical properties at temperatures higher than 1650℃. This study summarizes preparation of C/SiC load-carrying bearings for hinge by the Chemical Vapor Infiltration (CVI) method and C/SiC bolts for joints by the CVI + PIP (Polymer Impregnation and Pyrolysis) methods. The hinge bearing and bolts were examined in a simulated re-entry environment. Stress-oxidation was investigated under different stress levels from 0 to 200MPa up to 1800℃. The friction behavior of the hinge bearing system was studied under high loads (up to 25 kN) and low rotating velocities. The mechanical properties of the bolts with a thread connection were conducted under tensile and shear fatigue at both room temperature and elevated temperature. The results show that the stress-oxidation behavior of 2D-C/SiC composites in a combustion environment is a combined effect of extremely high load, high temperature, and oxidation. The load and temperature influenced the crack openings and thus the oxidation of carbon fibers in the precracked composites. The combustion environment mainly determined the time to failure of the specimens by oxidation damage under a high applied stress. Reliable thermal load-carrying ability and stable friction performance of the hinge bearing is demonstrated in high-temperature combustion environments with extremely high loads. The oxidation products of SiO2 at high temperatures between surfaces played an important role to modifies the friction by providing a protective layer. The room temperature tensile and shear strength of the bolts made of needled C/SiC are 139 MPa and 83 MPa, respectively. Even at 1800℃ in a combustion environment, the strengths still retained about 116MPa with a maximum decrease of 13%. More importantly, the bolts did not suffer significant mechanical degradation after tension-tension fatigue at 1 Hz for 24 h.

A key ABA hydrolase gene, OsABA8ox3 is involved in rice resistance to Nilaparvata lugens by affecting callose deposition

Yaodong Zhou,Litong Sun,Shuang Wang,Pengfei Xie,Jing-Lan Liu 한국응용곤충학회 2019 Journal of Asia-Pacific Entomology Vol.22 No.2

Abscisic acid (ABA) is an important plant hormone in regulating abiotic and biotic stresses. OsABA8ox3 is the key gene in ABA hydrolase genes, and plays an important role in controlling ABA level, but little is known in rice resistance to insects. We used rice osaba8ox3 T-DNA insertion mutant (knocking down the OsABA8ox3 gene) to elucidate rice resistance to the insect. There were obvious phenotype differences between the osaba8ox3 T-DNA insertion mutant and wild-type (WT), and the relative expression of synthetase genes in the osaba8ox3 mutant was higher, while the relative expression of hydrolase genes was lower than that of WT, respectively. The electrical penetration graph (EPG) recording indicated that the osaba8ox3 mutant had the less sucking phloem sap duration compared with WT, which indicated a significant increase in rice resistance to brown planthopper (Nilaparvata lugens; BPH). The callose deposition in the osaba8ox3 mutant increased by 60.39%, 52.2%, 26.6% and 31.7% than that of WT after BPH feeding for 0, 24, 48, and 72 h, respectively. These results showed OsABA8ox3 gene played an important role in rice resistance to BPH, and also provided new insights into the mechanism of callose deposition regulation in response to the piercing-sucking pest.

Effect of Ar dilution flow rate on LPCVD a boron-doped carbon coating from BCl3-C3H6-H2-Ar mixtures

Yongsheng Liu,Litong Zhang,Laifei Cheng,Wenbin Yang,Yongdong Xu 한양대학교 세라믹연구소 2009 Journal of Ceramic Processing Research Vol.10 No.3

A boron-doped carbon coating was deposited from a BCl3-C3H6-H2-Ar system by LPCVD. The effects of the Ar dilution flow rate on deposition rates, morphologies, compositions and bonding states were investigated. Deposition rates were almost the same, about 250 nm/h with different Ar dilution flow rate. Surface morphologies were also almost the same. The flat conchoidal aspect of the fracture surface transformed to a laminated structure with an increase in the Ar dilution flow rate. The carbon concentration was above 76.3 at.%, and the boron concentration was less than 17.9 at.%. The boron concentration increased with an increase in the Ar dilution flow rate, corresponding to a decreasing carbon concentration. The main bonding state of boron was B-sub-C and BC2O. The whole deposition process was dominated by a PyC formation reaction, which led to almost the same deposition rate with different Ar dilution flow rates. A boron-doped carbon coating was deposited from a BCl3-C3H6-H2-Ar system by LPCVD. The effects of the Ar dilution flow rate on deposition rates, morphologies, compositions and bonding states were investigated. Deposition rates were almost the same, about 250 nm/h with different Ar dilution flow rate. Surface morphologies were also almost the same. The flat conchoidal aspect of the fracture surface transformed to a laminated structure with an increase in the Ar dilution flow rate. The carbon concentration was above 76.3 at.%, and the boron concentration was less than 17.9 at.%. The boron concentration increased with an increase in the Ar dilution flow rate, corresponding to a decreasing carbon concentration. The main bonding state of boron was B-sub-C and BC2O. The whole deposition process was dominated by a PyC formation reaction, which led to almost the same deposition rate with different Ar dilution flow rates.

Updated Bayesian Network Meta-Analysis of Adjuvant Targeted Treatment Regimens for Early Human Epidermal Growth Factor Receptor-2 Positive Breast Cancer

Xinyan Li,Litong Yao,Mozhi Wang,Mengshen Wang,Xiang Li,Xueting Yu,Jingyi Guo,Haoran Dong,Xiangyu Sun,Yingying Xu 한국유방암학회 2020 Journal of breast cancer Vol.23 No.4

Purpose: Combining targeted agents with adjuvant chemotherapy prolongs survival in human epidermal growth factor receptor 2 (HER2)-positive breast cancer patients, but also increases the risk of adverse effects. The updated results of 3 randomized controlled trials (RCTs) were reported in 2019. Given the lack of adequate head-to-head pairwise assessment for anti-HER2 agents, network meta-analysis facilitates obtaining more precise inference for evidence-based therapy. Methods: RCTs comparing at least 2 anti-HER2 regimens in an adjuvant setting for HER2- positive early-stage breast cancer (EBC) were included. Hazard ratios for overall survival (OS) and disease free survival (DFS), with respective 95% confidence intervals were pooled for assessment of efficacy. A Bayesian statistical model was used, and odds ratios (ORs) for adverse events (AEs) were used to pool effect sizes. Results: We demonstrated that 1-year trastuzumab plus chemotherapy had increased efficacy compared to shorter or longer treatment duration. The OR of cardiac events gradually increased from 6 months to 1 and 2-year trastuzumab arms, relative to chemotherapy only. Compared to trastuzumab plus chemotherapy, dual HER2-targeting therapies increased DFS, especially for hormone receptor negative patients. Dual anti-HER2 blockade regimens revealed an increased probability of gastrointestinal reactions. As a second agent, pertuzumab showed significantly higher DFS and OS. Conclusion: We conclude that 1-year adjuvant trastuzumab should remain as the standard treatment for HER2-positive EBC patients, as it has greater efficacy and a manageable proportion of AEs. Clinical efficacy can be increased for hormone receptor-negative tumors by including a second HER2-targeted agent to the treatment regimen. For hormone receptor-positive cases with basal disease, it is acceptable to reduce the risk of cardiotoxicity by shortening the duration of trastuzumab.

Predictive and Prognostic Roles of Pathological Indicators for Patients with Breast Cancer on Neoadjuvant Chemotherapy

Xinyan Li,Mozhi Wang,Mengshen Wang,Xueting Yu,Jingyi Guo,Tie Sun,Litong Yao,Qiang Zhang,Yingying Xu 한국유방암학회 2019 Journal of breast cancer Vol.22 No.4

Currently, neoadjuvant chemotherapy is a standard therapeutic strategy for breast cancer, as it can provide timely and individualized chemo-sensitivity information and is beneficial for custom-designing subsequent treatment strategies. To accurately select candidates for neoadjuvant chemotherapy, the association between various immunohistochemical biomarkers of primary disease and tumor response to neoadjuvant chemotherapy has been investigated, and results have shown that certain pathological indicators evaluated after neoadjuvant chemotherapy are associated with long-term prognosis. The Food and Drug Administration (FDA) has recommended that complete pathological response can be used as a surrogate endpoint for neoadjuvant chemotherapy, which is related to better prognosis. Considering that residual tumor persists in the majority of patients after neoadjuvant chemotherapy, the value of various pathological indicators of residual disease in predicting the long-term outcomes is being extensively investigated. This review summarizes and compares various predictive and prognostic indicators for patients who have received neoadjuvant chemotherapy, and analyzes their efficacy in different breast cancer subtypes.