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Novel Buck Mode Three-Level Direct AC Converter with a High Frequency Link
Li, Lei,Guan, Yue,Gong, Kunshan,Li, Guangqiang,Guo, Jian The Korean Institute of Power Electronics 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.2
A novel family of Buck mode three-level direct ac converters with a high frequency link is proposed. These converters can transfer an unsteady high ac voltage with distortion into a regulated sinusoidal voltage with a low THD at the same frequency. The circuit configuration is constituted of a three-level converter, high frequency transformer, cycloconverter, as well as input and output filters. The topological family includes forward, push-pull, half-bridge, and full-bridge modes. In order to achieve a reliable three-level ac-ac conversion, and to overcome the surge voltage and surge current of the cycloconverter, a phase-shifted control strategy is introduced in this paper. A prototype is presented with experimental results to demonstrate that the proposed converters have five advantages including high frequency electrical isolation, lower voltage stress of the power switches, bi-directional power flow, low THD of the output voltage, and a higher input power factor.
Intermedins A and B; New Metabolites from Schisandra propinqua var. intermedia
Li, Hong-Mei,Lei, Chun,Luo, Yong-Ming,Li, Xiao-Nian,Li, Xiao-Lei,Pu, Jian-Xin,Zhou, San-Yun,Li, Rong-Tao,Sun, Han-Dong 대한약학회 2008 Archives of Pharmacal Research Vol.31 No.6
A new dibenzocyclooctadiene lignan, intermedin A (1), and a new natural bisabolane sesquiterpenoid, intermedin B (2), were isolated from the aerial parts of Schisandra propinqua var. intermedia. Their structures were elucidated on the basis of extensive spectroscopical analysis.
Li, Jian-Lei,Luo, Dang,Zhang, Zhi-Jiang The Korean Society for Computational and Applied M 2011 Journal of applied mathematics & informatics Vol.29 No.5
In this paper, we further investigate the local Hermitian and skew-Hermitian splitting (LHSS) iteration method and the modified LHSS (MLHSS) iteration method for solving generalized nonsymmetric saddle point problems with nonzero (2,2) blocks. When A is non-symmetric positive definite, the convergence conditions are obtained, which generalize some results of Jiang and Cao [M.-Q. Jiang and Y. Cao, On local Hermitian and Skew-Hermitian splitting iteration methods for generalized saddle point problems, J. Comput. Appl. Math., 2009(231): 973-982] for the generalized saddle point problems to generalized nonsymmetric saddle point problems with nonzero (2,2) blocks. Numerical experiments show the effectiveness of the iterative methods.
Jian-Lei Li,Dang Luo,Zhi-Jiang Zhang 한국전산응용수학회 2011 Journal of applied mathematics & informatics Vol.29 No.5
In this paper, we further investigate the local Hermitian and skew-Hermitian splitting (LHSS) iteration method and the modified LHSS (MLHSS) iteration method for solving generalized nonsymmetric saddle point problems with nonzero (2,2) blocks. When A is non-symmetric positive definite, the convergence conditions are obtained, which generalize some results of Jiang and Cao [M.-Q. Jiang and Y. Cao, On local Hermitian and Skew-Hermitian splitting iteration methods for generalized saddle point problems, J. Comput. Appl. Math., 2009(231): 973-982] for the generalized saddle point problems to generalized nonsymmetric saddle point problems with nonzero (2,2) blocks. Numerical experiments show the effectiveness of the iterative methods.
Novel Buck Mode Three-Level Direct AC Converter with a High Frequency Link
Lei Li,Yue Guan,Kunshan Gong,Guangqiang Li,Jian Guo 전력전자학회 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.2
A novel family of Buck mode three-level direct ac converters with a high frequency link is proposed. These converters can transfer an unsteady high ac voltage with distortion into a regulated sinusoidal voltage with a low THD at the same frequency. The circuit configuration is constituted of a three-level converter, high frequency transformer, cycloconverter, as well as input and output filters. The topological family includes forward, push-pull, half-bridge, and full-bridge modes. In order to achieve a reliable three-level ac-ac conversion, and to overcome the surge voltage and surge current of the cycloconverter, a phase-shifted control strategy is introduced in this paper. A prototype is presented with experimental results to demonstrate that the proposed converters have five advantages including high frequency electrical isolation, lower voltage stress of the power switches, bi-directional power flow, low THD of the output voltage, and a higher input power factor.
Li, Lei,Chen, Bao-Ding,Zhu, Hai-Feng,Wu, Shu,Wei, Da,Zhang, Jian-Quan,Yu, Li Asian Pacific Journal of Cancer Prevention 2014 Asian Pacific journal of cancer prevention Vol.15 No.17
Background: The aim of this meta-analysis was to compare sensitivities and specificities of fine needle aspiration (FNA) and core needle biopsy (CNB) in the diagnosis of thyroid cancer. Materials and Methods: Articles were screened in Medline, the Cochrane Library, EMBASE and Google Scholar, and subsequently included and excluded based on the patient/problem-intervention-comparison-outcome (PICO) principle. Primary outcome was defined in terms of diagnostic values (sensitivity and specificity) of FNA and CNB for thyroid cancer. Secondary outcome was defined as the accuracy of diagnosis. Compiled FNA and CNB results from the final studies selected as appropriate for meta-analysis were compared with cases for which final pathology diagnoses were available. Statistical analyses were performed for FNA and CNB for all of the selected studies together, and for individual studies using the leave-one-out approach. Results: Article selection and screening yielded five studies for meta-analysis, two of which were prospective and the other three retrospective, for a total of 1,264 patients. Pooled diagnostic sensitivities of FNA and CNB methods were 0.68 and 0.83, respectively, with specificities of 0.93 and 0.94. The areas under the summary ROC curves were 0.905 (${\pm}0.030$) for FNA and 0.745 (${\pm}0.095$) for CNB, with no significant difference between the two. No one study had greater influence than any other on the pooled estimates for diagnostic sensitivity and specificity. Conclusions: FNA and CNB do not differ significantly in sensitivity and specificity for diagnosis of thyroid cancer.
Yan, Jian,Liu, Xiao-Long,Han, Lu-Zhe,Xiao, Gang,Li, Ning-Lei,Deng, Yi-Nan,Yin, Liang-Chun,Ling, Li-Juan,Yu, Xiao-Yuan,Tan, Can-Liang,Huang, Xiao-Ping,Liu, Li-Xin Asian Pacific Journal of Cancer Prevention 2015 Asian Pacific journal of cancer prevention Vol.16 No.2
The aim of the present study was to investigate the expression of the transcription factor Ki-67, ER, PR, Her2/neu, p21, EGFR, and TOP II-${\alpha}$ in the tumor tissue of patients with invasive ductal carcinoma(IDC); in addition, we examined correlations between these markers. Two hundred and sixteen IDC patients, who were not previously been treated with chemo- or radiotherapy, were included in the study. All tumors were grade I-III. Expression of molecular markers was determined by immunohistochemical analysis on paraffin-embedded tissue sections. Follow-up data were collected for 3 months to 10 years and analyzed for tumor recurrence, survival time, and prognostic risk factors. We determined Ki-67 expression correlates with the expression of ER, PR, HER-2, EGFR, and TOP-${\alpha}$, as well as lymph node involvement, high tumor grade, lymphovascular invasion, high tumor stage, and high TNM stage in IDC. Positive Ki-67 expression was a risk factor for rapid tumor recurrence and may help tumor progression, leading to poor prognosis in IDC. Ki-67 was directly correlated with EGFR, TOP II-${\alpha}$, lymph node involvement, high tumor grade, lymphovascular invasion, high tumor stage, and high TNM stage in the hormone receptor subtypes of breast cancer. In triple negative breast cancer, Ki-67 correlated with TOP II-${\alpha}$. Expression of Ki-67 correlated with that of ER, PR, HER-2, EGFR, TOP II-${\alpha}$, and p21. In addition, the biomarker Ki-67 has a role as a prognostic factor and indicates a poor prognosis in IDC.
Yong Li,Chao Li,Lei Zhang,Weishen Zhu,Shucai Li,Jian Liu 한국지질과학협의회 2017 Geosciences Journal Vol.21 No.2
Apparent discontinuities can be easily found in natural rock medium owing to the constant motion and change of the Earth’s crust, which contains large amount of discontinuous surfaces such as faults, joints, cracks and so forth. Rock bolt is one of the most effective and economical reinforcing tools in practical geotechnical engineering for a long time. This paper investigates the mechanical properties, anchorage effect, cracking, and coalescence process of intact rock-like specimens, rock-like specimens containing flaws, and bolted rock-like specimens containing flaws. A series of uniaxial compression tests, splitting tests, and biaxial compression tests are performed on these specimens. Some findings can be observed from this study. (1) The number of rock bolt(s) and the anchoring angle have a great influence on the anchorage effect of rock bolt(s). With the increasing number of rock bolt(s), the uniaxial compressive strength (UCS), the splitting peak strength (which can be converted to the tensile strength), and biaxial compressive strength (BCS) can all be improved, whose variation tendencies do not follow a linear relationship. (2) The contributions to the tensile strength for rock bolt is greater than that to the UCS for the same-type specimen. (3) In the biaxial compression tests, with the increasing of the lateral pressures, the anchorage effect of rock bolt gradually declines and the lateral pressure plays a dominant role in improving the strength of the specimen. The failure characteristics of three types of laboratory tests have also been systematically analyzed in this paper.
Intermedins A and B; New Metabolites from Schisandra propinqua var. intermedia
Hong-Mei Li,Chun Lei,Yong-Ming Luo,Xiao-Nian Li,Xiao-Lei Li,Jian-Xin Pu,San-Yun Zhou,Rong-Tao Li,Han-Dong Sun 대한약학회 2008 Archives of Pharmacal Research Vol.31 No.6
A new dibenzocyclooctadiene lignan, intermedin A (1), and a new natural bisabolane sesquiterpenoid, intermedin B (2), were isolated from the aerial parts of Schisandra propinqua var. intermedia. Their structures were elucidated on the basis of extensive spectroscopical analysis.