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      • KCI등재

        An Analytical Solution for Voltage Stability Studies Incorporating Wind Power

        Yu-Zhang Lin,Li-Bao Shi,Liang-Zhong Yao,Yi-Xin Ni,Shi-Yao Qin,Rui-Ming Wang,Jin-Ping Zhang 대한전기학회 2015 Journal of Electrical Engineering & Technology Vol.10 No.3

        Voltage stability is one of the most critical security issues which has not yet been well resolved to date. In this paper, an analytical method called PQ plane analysis with consideration of the reactive power capability of wind turbine generator and the wake effect of wind farm is proposed for voltage stability study. Two voltage stability indices based on the proposed PQ plane analysis method incorporating the uncertainties of load-increasing direction and wind generation are designed and implemented. Cases studies are conducted to investigate the impacts of wind power incorporation with different control modes. Simulation results demonstrate that the constant voltage control based on reactive power capability significantly enhances voltage stability in comparison of the conventional constant power factor control. Some meaningful conclusions are obtained.

      • SCIESCOPUSKCI등재

        Effects of a traditional Chinese medicine formula and its extraction on muscle fiber characteristics in finishing pigs, porcine cell proliferation and isoforms of myosin heavy chain gene expression in myocytes

        Yu, Qin Ping,Feng, Ding Yuan,He, Xiao Jun,Wu, Fan,Xia, Min Hao,Dong, Tao,Liu, Yi Hua,Tan, Hui Ze,Zou, Shi Geng,Zheng, Tao,Ou, Xian Hua,Zuo, Jian Jun Asian Australasian Association of Animal Productio 2017 Animal Bioscience Vol.30 No.11

        Objective: This study evaluated the effects of a traditional Chinese medicine formula (TCMF) on muscle fiber characteristics in finishing pigs and the effects of the formula's extract (distilled water, ethyl acetate and petroleum ether extraction) on porcine cell proliferation and isoforms of myosin heavy chain (MyHC) gene expression in myocytes. Methods: In a completely randomized design, ninety pigs were assigned to three diets with five replications per treatment and six pigs per pen. The diets included the basal diet (control group), TCMF1 (basal diet+2.5 g/kg TCMF) and TCMF2 (basal diet+5 g/kg TCMF). The psoas major muscle was obtained from pigs at the end of the experiment. Muscle fiber characteristics in the psoas major muscle were analyzed using myosin ATPase staining. Cell proliferation was measured using 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) dye and cytometry. Isoforms of MyHC gene expression were detected by real-time quantitative polymerase chain reaction. Results: The final body weight and carcass weight of finishing pigs were increased by TCMF1 (p<0.05), while the psoas major muscle cross-sectional area was increased by TCMF (p<0.05). The cross-sectional area and diameter of psoas major muscle fiber Ι, IIA, and IIB were increased by TCMF2 (p<0.05). The cross-sectional area and fiber diameter of psoas major muscle fiber IIA and IIB were increased by diet supplementation with TCMF1 (p<0.05). Psoas major muscle fiber IIA and IIB fiber density from the pigs fed the TCMF1 diet and the type IIB fiber density from the pigs fed the TCMF2 diet were lower compared to pigs fed the control diet (p<0.05). Pigs fed TCMF2 had a higher composition of type Ι fiber and a lower percentage of type IIB fiber in the psoas major muscle (p<0.05). The expression levels of MyHC Ι, MyHC IIa, and MyHC IIx mRNA increased and the amount of MyHC IIb mRNA decreased in the psoas major muscle from TCMF2, whereas MyHC Ι and MyHC IIx mRNA increased in the psoas major muscle from TCMF1 (p<0.05). Peroxisome proliferator-activated receptor ${\gamma}$ $coactivator-1{\alpha}$ and CaN mRNA expression in the psoas major muscle were up-regulated by TCMF (p<0.05). Porcine skeletal muscle satellite cell proliferation was promoted by $4{\mu}g/mL$ and $20{\mu}g/mL$ TCMF water extraction (p<0.05). Both $1{\mu}g/mL$ and $5{\mu}g/mL$ of TCMF water extraction increased MyHC IIa, MyHC IIb, and MyHC IIx mRNA expression in porcine myocytes (p<0.05), while MyHC Ι mRNA expression in porcine myocytes was decreased by $5{\mu}g/mL$ TCMF water extraction (p<0.05). Porcine myocyte MyHC Ι and MyHC IIx mRNA expression were increased, and MyHC IIa and MyHC IIb mRNA expression were down-regulated by $5{\mu}g/mL$ TCMF ethyl acetate extraction (p<0.05). MyHC Ι and MyHC IIa mRNA expression in porcine myocytes were increased, and the MyHC IIb mRNA expression was decreased by $1{\mu}g/mL$ TCMF ethyl acetate extraction (p<0.05). Four isoforms of MyHC mRNA expression in porcine myocytes were reduced by $5{\mu}g/mL$ TCMF petroleum ether extraction (p<0.05). MyHC IIa mRNA expression in porcine myocytes increased and MyHC IIb mRNA expression decreased by $1{\mu}g/mL$ in a TCMF petroleum ether extraction (p<0.05). Conclusion: These results indicated that TCMF amplified the psoas major muscle cross-sectional area through changing muscle fiber characteristics in finishing pigs. This effect was confirmed as TCMF extraction promoted porcine cell proliferation and affected isoforms of MyHC gene expression in myocytes.

      • KCI등재

        Optimized Low-Switching-Loss PWM and Neutral-Point Balance Control Strategy of Three-Level NPC Inverters

        Shi-Zhou Xu,Chun-Jie Wang,Tian-Cheng Han,Xue-Ping Li,Xiang-Yu Zhu 전력전자학회 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.3

        Power loss reduction and total harmonic distortion(THD) minimization are two important goals of improving three-level inverters. In this paper, an optimized pulse width modulation (PWM) strategy that can reduce switching losses and balance the neutral point with an optional THD of three-level neutral-point-clamped inverters is proposed. An analysis of the two-level discontinuous PWM (DPWM) strategy indicates that the optimal goal of the proposed PWM strategy is to reduce switching losses to a minimum without increasing the THD compared to that of traditional SVPWMs. Thus, the analysis of the two-level DPWM strategy is introduced. Through the rational allocation of the zero vector, only two-phase switching devices are active in each sector, and their switching losses can be reduced by one-third compared with those of traditional PWM strategies. A detailed analysis of the impact of small vectors, which correspond to different zero vectors, on the neutral-point potential is conducted, and a hysteresis control method is proposed to balance the neutral point. This method is simple, does not judge the direction of midpoint currents, and can adjust the switching times of devices and the fluctuation of the neutral-point potential by changing the hysteresis loop width. Simulation and experimental results prove the effectiveness and feasibility of the proposed strategy.

      • KCI등재

        Research on Automatic Compensation Technology for Eccentricity of Grinding Wheel

        Shi-Ping Chen,Zhenzhong Wang,Hui Yu,Long-Qiao Lin 한국정밀공학회 2018 International Journal of Precision Engineering and Vol.19 No.8

        To ensure the installation precision of grinding wheel in precision grinding, the attitude of spindle axis must be adjusted to coincide with the geometric center of grinding wheel before the process. A special device that combined with piezoelectric actuators with threedegrees- of-freedom is designed. The corresponding method of automatic compensation technology for eccentricity of grinding wheel is developed. In order to calculate accurately eccentric angle and the eccentricity of the grinding wheel, high accuracy detection algorithm for eccentric signal of grinding wheel is given by the principle of rotary roundness error minimization firstly. Then a decomposition algorithm is proposed to decompose the eccentricity into three directions and the eccentricity can be eliminated by the coordinated control of the three piezoelectric actuators. Experimental results show that the average accuracy of the system is about 5.48 μm. Compared with the sine fitting algorithm, the algorithm presented for adjusting the eccentricity of grinding wheel in this paper is more stable and the accuracy is improved by about 78.2%, which shows that the proposed approach works successfully.

      • Cytokeratin 15 is an Effective Indicator for Progression and Malignancy of Esophageal Squamous Cell Carcinomas

        Shen, Yu-Hong,Xu, Cui-Ping,Shi, Zhi-Meng,Zhang, Yan-Jiao,Qiao, Ya-Guang,Zhao, He-Ping Asian Pacific Journal of Cancer Prevention 2016 Asian Pacific journal of cancer prevention Vol.17 No.9

        Purpose: To compare the expression level of CK 15 in normal esophageal and esophageal squamous-cell carcinoma (ESCC) tissues and analyse possible functions of CK15 in occurrence and development. Materials and Methods: Immunohistochemistry was used to compare CK14, CK15 and proliferating cell nuclear antigen (PCNA) expression levels in ESCCs. Expression level of CK15 was also assessed by Western blotting. In addition, levels of CK15, cytokeratin 19 fragment antigen 21-1 (CYFRA21-1) and PCNA were detected in serum by enzymelinked immunosorbent assay (ELISA) and chemiluminescence methods. Relationships between clinicopathological parameters and CK14 and CK15 expression were then analyzed. Results: According to immunohistochemistry, in esophageal and intraepithelial neoplasia (SIN) tissues, the expression of CK14, CK15 and PCNA localized to basal layer of the epithelium. CK14 and CK15 levels were higher in normal esophageal squamous epithelial tissue than in SIN and ESCC, and greater in highly differentiated than poorly differentiated carcinoma tissue. By Western blotting, we found more pronounced expression of CK15 in normal esophageal tissue, compared with carcinoma tissue. The specificity of changed CK15 and CYFRA21-1 expression was respectively 90.0% and 96.7% in serum of ESCC patients. Joint detection could improve the sensitivity of esophageal carcinoma diagnosis. Relationships between CK14, CK15 expression and clinical parameters were not statistically significant (P>0.05). Postoperative survival in patients of CK14, CK15 positive expression was longer than with negative expression ($x^2=4.35$, P=0.037; $x^2=9.852$, P=0.002). Conclusions: CK15 expression decreased in esophageal squamous cell carcinoma tissue and serum of esophageal squamous carcinoma patients. We infer that CK15 may play an important role for the occurrence and development of esophageal squamous-cell carcinoma. In the future, CK15 may be used for the diagnosis, treatment and prognostic evaluation of esophageal squamous-cell carcinoma.

      • KCI등재

        Circulating Low Absolute CD4+ T Cell Counts May Predict Poor Prognosis in Extranodal NK/T-Cell Lymphoma Patients Treating with Pegaspargase-Based Chemotherapy

        Ya-Ping Zhang,Run Zhang,Hua-Yuan Zhu,Li Wang,Yu-Jie Wu,Jin-Hua Liang,Wen-Yu Shi,Hong Liu,Wei Xu,Jian-Yong Li 대한암학회 2019 Cancer Research and Treatment Vol.51 No.1

        Purpose Extranodal natural killer/T-cell lymphoma, nasal type (ENKTL) is a rare subtype of non- Hodgkin lymphoma, and asparaginase-based regimens are the best first-line treatments. Data on the role of specific circulating lymphocyte subsets in the progression of ENKTL are limited. The aim of this study was to investigate the clinical correlation and distribution of circulating absolute CD4+ T-cell counts (ACD4Cs) in ENKTL. Materials and Methods We retrospectively searched medical records for 70 newly diagnosed ENKTL patients treated with pegaspargase-based regimens. Comparison of ACD4Cs as a continuous parameter in different groups was calculated. Univariate and multivariate analyses were used to assess prognostic factors for overall survival (OS) and progression-free survival (PFS). Results Stage III/IV, B symptoms, elevated lactate dehydrogenase, monocytopenia, high-intermediate and high risk International Prognostic Index (IPI) and Korean Prognostic Index (KPI), high risk Prognostic Index of Natural Killer Lymphoma (PINK), and lower lymphocytes were significantly associated with low ACD4C at diagnosis. With a median follow-up time of 32 months, patients who had an ACD4C < 0.30109/L had a worse OS. Median OS was 11 months and median PFS was 5 months in the low ACD4C cohort. There were significant differences in both OS and PFS between the two cohorts. Moreover, multivariate Cox analysis identified ACD4Cs as an independent predictor for OS and PFS. Conclusion Low ACD4Cs were associated with poorer survival and could act as a negative predictor for ENKTL patients treated with asparaginase-based regimens.

      • SCIESCOPUSKCI등재

        Optimized Low-Switching-Loss PWM and Neutral-Point Balance Control Strategy of Three-Level NPC Inverters

        Xu, Shi-Zhou,Wang, Chun-Jie,Han, Tian-Cheng,Li, Xue-Ping,Zhu, Xiang-Yu The Korean Institute of Power Electronics 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.3

        Power loss reduction and total harmonic distortion(THD) minimization are two important goals of improving three-level inverters. In this paper, an optimized pulse width modulation (PWM) strategy that can reduce switching losses and balance the neutral point with an optional THD of three-level neutral-point-clamped inverters is proposed. An analysis of the two-level discontinuous PWM (DPWM) strategy indicates that the optimal goal of the proposed PWM strategy is to reduce switching losses to a minimum without increasing the THD compared to that of traditional SVPWMs. Thus, the analysis of the two-level DPWM strategy is introduced. Through the rational allocation of the zero vector, only two-phase switching devices are active in each sector, and their switching losses can be reduced by one-third compared with those of traditional PWM strategies. A detailed analysis of the impact of small vectors, which correspond to different zero vectors, on the neutral-point potential is conducted, and a hysteresis control method is proposed to balance the neutral point. This method is simple, does not judge the direction of midpoint currents, and can adjust the switching times of devices and the fluctuation of the neutral-point potential by changing the hysteresis loop width. Simulation and experimental results prove the effectiveness and feasibility of the proposed strategy.

      • SCIESCOPUSKCI등재

        An Analytical Solution for Voltage Stability Studies Incorporating Wind Power

        Lin, Yu-Zhang,Shi, Li-Bao,Yao, Liang-Zhong,Ni, Yi-Xin,Qin, Shi-Yao,Wang, Rui-Ming,Zhang, Jin-Ping The Korean Institute of Electrical Engineers 2015 Journal of Electrical Engineering & Technology Vol.10 No.3

        Voltage stability is one of the most critical security issues which has not yet been well resolved to date. In this paper, an analytical method called PQ plane analysis with consideration of the reactive power capability of wind turbine generator and the wake effect of wind farm is proposed for voltage stability study. Two voltage stability indices based on the proposed PQ plane analysis method incorporating the uncertainties of load-increasing direction and wind generation are designed and implemented. Cases studies are conducted to investigate the impacts of wind power incorporation with different control modes. Simulation results demonstrate that the constant voltage control based on reactive power capability significantly enhances voltage stability in comparison of the conventional constant power factor control. Some meaningful conclusions are obtained.

      • Simulation of 7050 Wrought Aluminum Alloy Wheel Die Forging and its Defects Analysis based on DEFORM

        HUANG Shi-Quan,YI You-Ping,ZHANG Yu-Xun 한국소성가공학회 2010 기타자료 Vol.2010 No.6

        Defects such as folding, intercrystalline cracking and flow lines outcrop are very likely to occur in the forging of aluminum alloy. Moreover, it is difficult to achieve the optimal set of process parameters just by trial and error within an industrial environment. In producing 7050 wrought aluminum alloy wheel, a rigid-plastic finite element method (FEM) analysis has been performed to optimize die forging process. Processing parameters were analyzed, focusing on the effects of punch speed, friction factor and temperature. Meanwhile, mechanism as well as the evolution with respect to the defects of the wrought wheel was studied in details. From an analysis of the results, isothermal die forging was proposed for producing 7050 aluminum alloy wheel with good mechanical properties. Finally, verification experiment was carried out on hydropress.

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