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Wavelet PWM Technique for Single-Phase Three-Level Inverters
Chun-Fang Zheng,Bo Zhang,Dong-Yuan Qiu,Xiao-Hui Zhang,Le-Ming Xiao 전력전자학회 2015 JOURNAL OF POWER ELECTRONICS Vol.15 No.6
The wavelet PWM (WPWM) technique has been applied in two-level inverters successfully, but directly applying the WPWM technique to three-level inverters is impossible. This paper proposes a WPWM technique suitable for a single-phase three-level inverter. The work analyzes the control strategy with the WPWM and obtains the design of its parameters. Compared with the SPWM technique for a single-phase three-level inverter under the same conditions, the WPWM can obtain high magnitudes of the output fundamental frequency component, low total harmonic distortion, and simpler digital implementation. The feasibility experiment is given to verify of the proposed WPWM technique.
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Zheng, Chun-Long,Qiu, Chen,Shen, Mei-Xiao,Qu, Xiao,Zhang, Tie-Hong,Zhang, Ji-Hong,Du, Jia-Jun Asian Pacific Journal of Cancer Prevention 2015 Asian Pacific journal of cancer prevention Vol.16 No.5
Background: The vascular endothelial growth factor family has been implicated in tumorigenesis and metastasis. The prognostic value of each vascular endothelial growth factor family member, particular VEGF/VEGFR co-expression, in patients with non-small lung cancer remains controversial. Materials and Methods: Relevant literature was identified by searching PubMed, EMBASE and Web of Science. Studies evaluating expression of VEGFs and/or VEGFRs by immunohistochemistry or ELISA in lung cancer tissue were eligible for inclusion. Hazard ratios (HRs) and 95% confidence intervals (CIs) from individual study were pooled by using a fixed- or random-effect model, heterogeneity and publication bias analyses were also performed. Results: 74 studies covering 7,631 patients were included in the meta-analysis. Regarding pro-angiogenesis factors, the expression of VEGFA (HR=1.633, 95%CI: 1.490-1.791) and VEGFR1 (HR=1.924, 95%CI: 1.220-3.034) was associated separately with poor survival. Especially, VEGFA over-expression was an independent prognostic factor in adenocarcinoma (ADC) (HR=1.775, 95%CI: 1.384-2.275) and SCC (HR=2.919, 95%CI: 2.060-4.137). Co-expression of VEGFA/VEGFR2 (HR=2.011, 95%CI: 1.405-2.876) was also significantly associated with worse survival. For lymphangiogenesis factors, the expression of VEGFC (HR=1.611, 95%CI: 1.407-1.844) predicted a poor prognosis. Co-expression of VEGFC/VEGFR3 (HR=2.436, 95%CI: 1.468-4.043) emerged as a preferable prognostic marker. Conclusions: The expression of VEGFA (particularly in SCC and early stage NSCLC), VEGFC, VEGFR1 indicates separately an unfavorable prognosis in patients with NSCLC. Co-expression VEGFA/VEGFR2 is comparable with VEGFC/VEGFR3, both featuring sufficient discrimination value as preferable as prognostic biologic markers.
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Thermal Behavior Analysis and Thermal Error Compensation for Motorized Spindle of Machine Tools
Zheng-Chun Du,Si-Yu Yao,Jian-Guo Yang 한국정밀공학회 2015 International Journal of Precision Engineering and Vol. No.
The thermal error deformation of motorized spindle plays an important role in the precision machining, while error compensation has been proved to be a cost-effective way. Herein a symmetrical solution for the thermal error problem of spindle is proposed based on the thermal behavior analysis. Firstly, the heat generating and transfer mechanism are described considering the heat sources. Next, ANSYS is used to achieve the steady-state and the transient thermal field distribution as well as the related deformation with the given thermal load and boundary condition. Furthermore, the NEM is proposed to predict the thermal error under random rotating speed with no use of thermal sensors, followed by the determination of two important parameters. The verification experiment of the thermal error under random rotating speed is executed. The External Machine Zero Point Shift function of the CNC system is adopted to develop the real-time compensation system on the spindle of HDBS-63 machining center. The maximum axial thermal error is greatly reduced from 55 to 16 um, while the radial one similarly reduced from 15 to 6 um. Both are improved 73% and 63% respectively. The experiment results show that NEM method is simple but of good reliability and practicality.
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An Improved Wavelet PWM Technique with Output Voltage Amplitude Control for Single-phase Inverters
Chun-Fang Zheng,Bo Zhang,Dong-Yuan Qiu,Xiao-Hui Zhang,Rui Li 전력전자학회 2016 JOURNAL OF POWER ELECTRONICS Vol.16 No.4
Unlike existing pulse-width modulation (PWM) techniques, such as sinusoidal PWM and random PWM, the wavelet PWM (WPWM) technique based on a Harr wavelet function can achieve a high fundamental component for the output voltage, low total harmonic distortion, and simple digital implementation. However, the original WPWM method lacks output voltage control. Thus, the practical application of the WPWM technique is limited. This study proposes an improved WPWM technique that can regulate output voltage amplitude with the addition of a parameter. The relationship between the additional parameter and the output voltage amplitude is analyzed in detail. Experimental results verify that the improved WPWM exhibits output voltage control in addition to all the merits of the WPWM technique.
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An Improved Wavelet PWM Technique with Output Voltage Amplitude Control for Single-phase Inverters
Zheng, Chun-Fang,Zhang, Bo,Qiu, Dong-Yuan,Zhang, Xiao-Hui,Li, Rui The Korean Institute of Power Electronics 2016 JOURNAL OF POWER ELECTRONICS Vol.16 No.4
Unlike existing pulse-width modulation (PWM) techniques, such as sinusoidal PWM and random PWM, the wavelet PWM (WPWM) technique based on a Harr wavelet function can achieve a high fundamental component for the output voltage, low total harmonic distortion, and simple digital implementation. However, the original WPWM method lacks output voltage control. Thus, the practical application of the WPWM technique is limited. This study proposes an improved WPWM technique that can regulate output voltage amplitude with the addition of a parameter. The relationship between the additional parameter and the output voltage amplitude is analyzed in detail. Experimental results verify that the improved WPWM exhibits output voltage control in addition to all the merits of the WPWM technique.
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Wavelet PWM Technique for Single-Phase Three-Level Inverters
Zheng, Chun-Fang,Zhang, Bo,Qiu, Dong-Yuan,Zhang, Xiao-Hui,Xiao, Le-Ming The Korean Institute of Power Electronics 2015 JOURNAL OF POWER ELECTRONICS Vol.15 No.6
The wavelet PWM (WPWM) technique has been applied in two-level inverters successfully, but directly applying the WPWM technique to three-level inverters is impossible. This paper proposes a WPWM technique suitable for a single-phase three-level inverter. The work analyzes the control strategy with the WPWM and obtains the design of its parameters. Compared with the SPWM technique for a single-phase three-level inverter under the same conditions, the WPWM can obtain high magnitudes of the output fundamental frequency component, low total harmonic distortion, and simpler digital implementation. The feasibility experiment is given to verify of the proposed WPWM technique.
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Zheng, Chun-Hua,Quan, Yuan,Li, Yi-Yang,Deng, Wei-Guo,Shao, Wen-Jing,Fu, Yan Asian Pacific Journal of Cancer Prevention 2014 Asian Pacific journal of cancer prevention Vol.15 No.4
Objective: Forkhead box C2 (FOXC2) is a member of the winged helix/forkhead box (Fox) family of transcription factors. It has been suggested to regulate tumor vasculature, growth, invasion and metastasis, although it has not been studied in cervical cancer. Here, we analyzed FOXC2 expression in cervical tissues corresponding to different stages of cervical cancer development and examined its correlation with clinicopathological characteristics. In addition, we examined the effects of targeting FOXC2 on the biological behavior of human cervical cancer cells. Methods: The expression of FOXC2 in normal human cervix, CIN I-III and cervical cancer was examined by immunohistochemistry and compared among the three groups and between cervical cancers with different pathological subtypes. Endogenous expression of FOXC2 was transiently knocked down in human Hela and SiHa cervical cells by siRNA, and cell viability and migration were examined by scratch and CCK8 assays, respectively. Results: In normal cervical tissue the frequency of positive staining was 25% (10/40 cases), with a staining intensity (PI) of $0.297{\pm}0.520$, in CIN was 65% (26/40cases), with a PI of $3.00{\pm}3.29$, and in cancer was 91.8% (68/74 cases), with a PI of $5.568 {\pm}3.449$. The frequency was 100% in adenocarcinoma (5/5 cases) and 91.3% in SCCs (63/69 cases). The FOXC2 positive expression rate was 88.5% in patients with cervical SCC stage I and 100% in stage II, showing significant differences compared with normal cervix and CIN. With age, pathologic differentiation degree and tumor size, FOXC2 expression showed no significant variation. On transient transfection of Hela and SiHa cells, FOXC2-siRNA inhibition rates were 76.2% and 75.7%; CCK8 results showed reduced proliferation and relative migration (in Hela cells from $64.5{\pm}3.16$ to $49.5{\pm}9.24$ and in SiHa cells from $60.1{\pm}3.05$ to $44.3{\pm}3.98$) (P < 0.05). Conclusion: FOXC2 gene expression increases with malignancy, especially with blood vessel hyperplasia and invasion degree. Targeted silencing was associated with reduced cell proliferation as well as invasion potential.
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Cold chain time- and temperature-controlled transport of vaccines: a simulated experimental study
Chun Zheng Ng,Yen Loong Lean,Siang Fei Yeoh,Qi Ying Lean,Kah Seng Lee,Amal Khalil Suleiman,Kai Bin Liew,Yaman Walid Kassab,Yaser Mohammed Al-Worafi,Long Chiau Ming 대한백신학회 2020 Clinical and Experimental Vaccine Research Vol.9 No.1
Purpose: The objective of this research was to examine the cold chain temperature maintenance for the supply of vaccines and other biological products by pharmaceutical wholesaler. Materials and Methods: In this study, six configurations using cold vaccine boxes or bags made with different materials, with and without insulation, of different sizes, and number of coolant-packs were used to simulate the configuration used by the pharmaceutical wholesalers for transportation of vaccine. Model vaccines (vial, n=10) were packed using these six configurations which then stored in an incubator at 38ºC and monitored for 24 hours. Each configuration was tested repeatedly for 5 times. Results: In term of compliance to 2°C–8°C, four out of six tested configurations are effective in cold chain transportation. The effectiveness is highly dependent on the type of passive containers used, size of cold boxes, insulation, and number of coolant-packs. The configuration with a larger polystyrene foam box with five coolant-packs maintained the required temperature up to 23 hours. In contrast, configurations using a polystyrene foam box with four coolant-packs and a large vaccine cold box with two coolant-packs failed to reach below 8ºC throughout the 24 hours. Conclusion: Packaging method, the material and size of the container could have a direct impact on the effectiveness of cold chain temperature maintenance. Polystyrene foam box, cold box with polyethylene interior lining and polypropylene insulation, a cooler bag with proper number of ice packs could be effectively used for
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