http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Wei‑dong Zhang,Junye Ren,Bin Liu,Yong Liu,Zhenggang Wu,Jingwen Qiu 대한금속·재료학회 2020 METALS AND MATERIALS International Vol.26 No.7
Ti–36Nb–2Ta–3Zr–0.35O (TNTZO) alloy is an excellent candidate for biomedical applications. In this study, a new methodcombining cold-swaging and cold-drawing was used to fabricate the TNTZO alloy wires with 0.3 mm diameter for orthodonticapplications. The microstructure and mechanical properties of cold-drawn and annealed TNTZO wires (referred toas TNTZO0.3and TNTZO0.3(HT), respectively) were investigated. The results show that the microstructure of cold drawnTNTZO0.3consists of main-sized elongated grains with 70 nm width. After annealing at 700 °C for 5 min, the microstructureof TNTZO0.3(HT) wires becomes equiaxial with a grain size of ~ 5 μm. The cold drawn TNTZO0.3wires exhibit improvedmechanical properties, higher tensile strength (about 1000 MPa) and similar elastic modulus (69 GPa), compared to annealedTNTZO0.3(HT) wires. Besides, TNTZO0.3has higher creep resistance and lower stress exponent (around 2), compared to Tiwires and TC4 wires with the same diameter. These results prove that TNTZO0.3wires have most of the ideal characteristicsof orthodontic wires.
Yingbo Zhang,Dening Zou,Xiaoqiao Wang,Fengshe Xia,Yong Wang,Wei Zhang 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.7
The effect of Al content on the microstructure and ductile-brittle transition temperature (DBTT) of 18Cr–Al–Si ferritic heatresistantstainless steel have been studied by Charpy impact testing over temperatures ranging from 20 to 90 ℃. Charpy impacttest results show that DBTT increased with increasing Al content. Meanwhile, fracture morphology changed with increasingAl content, where the amount of dimples decreased and cleavage facets increased, indicating increases in the tendency forbrittle fracture. Furthermore, ferrite grain size, volume fraction and size of (Cr, Fe)23C6 carbides increased with increasingAl content, which led to decreasing toughness and increasing DBTT.
EMI Noise Source Reduction of Single-Ended Isolated Converters Using Secondary Resonance Technique
Zhang-yong Chen,Yong Chen,Qiang Chen,Wei Jiang,Rongqiang Zhong 전력전자학회 2019 JOURNAL OF POWER ELECTRONICS Vol.19 No.2
Aiming at the problems of large dv/dt and di/dt in traditional single-ended converters and high electromagnetic interference (EMI) noise levels, a single-ended isolated converter using the secondary resonance technique is proposed in this paper. In the proposed converter, the voltage stress of the main power switch can be reduced and the voltage across the output diode is clamped to the output voltage when compared to the conventional flyback converter. In addition, the peak current stress through the main power switch can be decreased and zero current switching (ZCS) of the output diode can be achieved through the resonance technique. Moreover, the EMI noise coupling path and an equivalent model of the proposed converter topology are presented through the operational principle of the proposed converter. Analysis results indicate that the common mode (CM) EMI noise and the differential mode (DM) EMI noise of such a converter are deduced since the frequency spectra of the equivalent controlled voltage sources and controlled current source are decreased when compared with the traditional flyback converter. Furthermore, appropriate parameter selection of the resonant circuit network can increase the equivalent impedance in the EMI coupling path in the low frequency range, which further reduces the common mode interference. Finally, a simulation model and a 60W experimental prototype of the proposed converter are built and tested. Experimental results verify the theoretical analysis.
Zhang, Peng,Jin, Yue-Fei,Zhang, Qiao,Wu, Yi-Ming,Wu, Wei-Dong,Yao, Wu,Wu, Yong-Jun,Li, Zhi-Tao,Zhao, Yong,Liu, Yu,Feng, Fei-Fei Asian Pacific Journal of Cancer Prevention 2014 Asian Pacific journal of cancer prevention Vol.15 No.12
Background: We sought to evaluate the role of tumor associated macrophages (TAMs) on the promotion of coal tar pitch extract (CTPE)-induced tumorigenesis of human bronchial epithelial cells (BEAS-2B) and tumor metastasis in nude mice, and related mechanisms. Materials and Methods: BEAS-2B cells were first treated with 2.4 mg/mL CTPE for 72 hours. After removal of CTPE, the cells were continuously cultured and passaged using trypsin-EDTA. THP-1 cells were used as macrophage-like cells. BEAS-2B cells under different conditions (n=6/group) were injected into the back necks of nude mice, and alterations of tumor xenograft growth, indicative of tumorigenicity, and tumor metastasis were determined. Pathological changes (tumor nests and microvascular lesions) of HE-stained tumor tissues were also evaluated. The expression of AP-1(c-Jun) in xenografts and metastatic tumors was determined using immunohistochemistry. Results: Tumor size and weight in nude mice transplanted with the mixture of CTPE-induced passage 30 BEAS-2B and THP-1 cells (2:1) were increased compared to those from the CTPE-treated BEAS-2B cells at passage 30 alone at different observation time points. Tumor metastasis to lymph nodes and liver was only detected after transplantation of a mixture the two kinds of cells. The numbers of tumor nests and microvascular lesions, and the expression levels of AP-1 (c-Jun) in tumors from the mixture of two kinds of cells were increased apparently in contrast to those in tumor from the CTPE-treated BEAS-2B cells of passage 30 alone. In addition, there was positive correlation between AP-1 (c-Jun) expression level and the number of microvascular lesions, or between AP-1 (c-Jun) expression level and tumor metastasis in these two groups. Conclusions: TAMs not only facilitate tumorigenesis transformation of CTPE-induced BEAS-2B cells, but also promote tumor growth, angiogenesis and metastasis in nude mice in vivo, which may be mediated by AP-1.
Fast Thresholding Based on Improved Minimum Cross Entropy
Yong-Liang Zhang,Wen Zhang,Gang Xiao,Jia-Fa Mao,Shan-Shan Huang,Xiao-Wei Zheng 제어로봇시스템학회 2012 제어로봇시스템학회 국제학술대회 논문집 Vol.2012 No.10
Image segmentation is an important and classic problem in image processing and computer vision. Thresholding is applied to many fields, because of its less computation and stable performance. The key of thresholding method is to determine the adaptive threshold. In order to segment biological image effectively, a new adaptive thresholding method is proposed. First, two dimension minimum entropy is computed based on gray-gradient co-occurrence matrix; and then the genetic algorithm is applied to encode the two-dimension threshold vector; Finally, the optimum threshold is calculated based on fitness function and uniformity measurement(UM). Experimental results show that this method has three advantages: 1) improve computational efficiency so that it can run in real time; 2) retain more object and edge information so that it can meet the practical requirement; 3) robust to the uneven distribution of light.
Wei, Wei-Hong,Cai, Xiu-Yu,Xu, Tao,Zhang, Guo-Yi,Wu, Yong-Feng,Feng, Wei-Neng,Lin, Li,Deng, Yan-Ming,Lu, Qiu-Xia,Huang, Zhe-Li Asian Pacific Journal of Cancer Prevention 2012 Asian Pacific journal of cancer prevention Vol.13 No.3
Background and Purpose: Cisplatin is the most common chemotherapeutic agent for loco-regionally advanced nasopharyngeal carcinoma (NPC); however, toxicity is a limiting factor for some patients. We retrospectively compared the efficacy and toxicity of weekly docetaxel-based and cisplatin-based concurrent chemoradiotherapy in loco-regionally advanced NPC. Methods and Materials: Eighty-four patients with Stage III and IVA-B NPCs, treated between 2007 and 2008, were retrospectively analyzed. Thirty received weekly docetaxel-based concurrent chemotherapy, and 43 were given weekly cisplatin-based concurrent chemotherapy. Radiotherapy was administered using a conventional technique (seven weeks, 2.0 Gy per fraction, total dose 70-74 Gy) with 6-8 Gy boosts for some patients with locally advanced disease. Results: Median follow-up time was 42.3 months (range, 8.6-50.8 months). There were no significant differences in the 3-year loco-regional failure-free survival (85.6% vs. 92.3%; p=0.264), distant failure-free survival (87.0% vs. 92.5%; p=0.171), progression-free survival (85.7% vs. 88.4%; p=0.411) or overall survival (86.5% vs. 92.5%, p=0.298) of patients treated concurrently with docetaxel or cisplatin. Severe toxicity was not common in either group. Conclusions: Weekly docetaxel-based concurrent chemoradiotherapy is potentially effective and has a tolerable toxicity; however, further investigations are required to determine if docetaxel is superior to cisplatin for advanced stage NPC.
Zhang Jun Qing,Duan Jin Ao,Wang Yong,Li Yong Hui,Lai Wei Yong,Li Hai Long,Pei Li Xia 대한약학회 2012 Archives of Pharmacal Research Vol.35 No.12
Chemical investigation of the fruits of Alpinia oxyphylla led to an isolation of the two new natural products, 9-hydroxy epinootkatol (1) and (S)-2-pentanol-2-O-β-D-glucopyranoside (2), in addition to the nine known compounds, pinocembrin (3), tectochrysin (4), izalpinin (5), nookatone (6), yakuchinone A (7), protocatechuic acid (8), β-sitosterol (9), daucosterol (10) and β-sitosterol palmitate (11). Their structures were elucidated on the basis of physicochemical constants and NMR spectral data analysis. The effects of the isolated components on nitric oxide production in LPS-induced RAW 264.7 macrophages were examined. The two new natural compounds showed inhibitory activities with IC50 values of 21.8 and 32.8 μg/mL, respectively.
ZVT Series Capacitor Interleaved Buck Converter with High Step-Down Conversion Ratio
Zhang-yong Chen,Yong Chen,Wei Jiang,Tiesheng Yan 전력전자학회 2019 JOURNAL OF POWER ELECTRONICS Vol.19 No.4
Voltage step-down converters are very popular in distributed power systems, voltage regular modules, electric vehicles, etc. However, a high step-down voltage ratio is required in many applications to prevent the traditional buck converter fromoperating at extreme duty cycles. In this paper, a series capacitor interleaved buck converter with a soft switching technique isproposed. The DC voltage ratio of the proposed converter is half that of the traditional buck converter and the voltage stressacross the one main switch and the diodes is reduced. Moreover, by paralleling the series connected auxiliary switch and theauxiliary inductor with the main inductor, zero voltage transition (ZVT) of the main switches can be obtained without increasingthe voltage or current stress of the main power switches. In addition, zero current turned-on and zero current switching (ZCS) ofthe auxiliary switches can be achieved. Furthermore, owing to the presence of the auxiliary inductor, the turned-off rate of theoutput diodes can be limited and the reverse-recovery switching losses of the diodes can be reduced. Thus, the efficiency of theproposed converter can be improved. The DC voltage gain ratio, soft switching conditions and a design guideline for the criticalparameters are given in this paper. A loss analysis of the proposed converter is shown to demonstrate its advantages overtraditional converter topologies. Finally, experimental results obtained from a 100V/10V prototype are presented to verify theanalysis of the proposed converter.