Calculation and analysis of switching losses in IGBT devices based on switching transient processes

Hao, Bin,Peng, Cheng,Tang, Xinling,Zhao, Zhibin The Korean Institute of Power Electronics 2022 JOURNAL OF POWER ELECTRONICS Vol.22 No.10

Accurately revealing the generation mechanism and the mathematical relationship with system parameters of the power loss in the switching transients of high-voltage large power IGBT devices is very important for the device selection and circuit design of converter equipment. To reveal the mechanism of generating switching losses, this paper analyzes the switching transient processes of the IGBT devices in the basic commutation circuit in detail. Then this paper proposes an accurate calculation method based on a finite state machine (FSM) for the switching losses of IGBT devices, and verifies the correctness of this method. To further reveal the mathematical relationships among switching losses, device parameters, and loop parameters, approximate analytical formulas for the switching loss of different switching transient processes are mathematically derived, which can provide a theoretical basis for reducing the switching losses in converters.

Enhanced electrical conductivity of nanocomposites containing hybrid fillers of carbon nanotubes and carbon black.

Ma, Peng-Cheng,Liu, Ming-Yang,Zhang, Hao,Wang, Sheng-Qi,Wang, Rui,Wang, Kai,Wong, Yiu-Kei,Tang, Ben-Zhong,Hong, Soon-Hyung,Paik, Kyung-Wook,Kim, Jang-Kyo American Chemical Society 2009 ACS APPLIED MATERIALS & INTERFACES Vol.1 No.5

<P>Nanocomposites reinforced with hybrid fillers of carbon nanotubes (CNTs) and carbon black (CB) are developed, aiming at enhancing the electrical conductivity of composites with balanced mechanical properties while lowering the cost of the final product. Epoxy-based nanocomposites were prepared with varying combinations of CNTs and CB as conducting fillers, and their electrical and mechanical properties were evaluated. It was shown that the addition of CNTs in CB composites enhanced the electrical conductivity of composites: a low percolation threshold was achieved with 0.2 wt % CNTs and 0.2 wt % CB particles. The CB particles also enhanced the ductility and fracture toughness of nanocomposites, confirming the synergistic effect of CB as a multifunctional filler. The novelty of this work lies in the synergy arising from the combination of two conducting fillers with unique geometric shapes and aspect ratios as well as different dispersion characteristics, which have not been specifically considered previously.</P>

Research on Dynamic Characteristics for Longwall Shearer Cutting Transmission System with Varying Cutting Speed

Yang Yang,Hao Fan,Peng-cheng Ma 한국정밀공학회 2017 International Journal of Precision Engineering and Vol.18 No.8

A new longwall shearer cutting transmission system with variable cutting speed (LSCT-V) is presented to overcome the weaknesses of the traditional longwall shearer cutting transmission system (LSCT) with constant cutting speed. The dynamic model of the LSCTV and LSCT, which includes a cutting-motor rotator and drum, are established in AMESim, and the dynamic response of each system is analyzed using AMESim. Simulation results show that the function of frequency control for the designed LSCT-V system can be achieved, compared with the dynamic behavior of LSCT system under step torque load. The dynamic characteristics of the LSCT-V system are very close when working in constant or varying cutting speeds.

Transcriptional regulation of Glis2 in hepatic fibrosis

Gong Huan-Yu,Zhou Peng-Cheng,Zhang Hao-Ye,Chen Li-Min,Zhou Yang-Mei,Liu Zhen-Guo 생화학분자생물학회 2023 Experimental and molecular medicine Vol.55 No.-

The role of Gli-similar 2 (Glis2) in hepatic fibrosis (HF) is controversial. In this study, we focused on the functional and molecular mechanisms involved in the Glis2-mediated activation of hepatic stellate cells (HSCs)—a milestone event leading to HF. The expression levels of Glis2 mRNA and protein were significantly decreased in the liver tissues of patients with severe HF and in mouse fibrotic liver tissues as well as HSCs activated by TGFβ1. Functional studies indicated that upregulated Glis2 significantly inhibited HSC activation and alleviated BDL-induced HF in mice. Downregulation of Glis2 was found to correlate significantly with DNA methylation of the Glis2 promoter mediated by methyltransferase 1 (DNMT1), which restricted the binding of hepatic nuclear factor 1-α (HNF1-α), a liver-specific transcription factor, to Glis2 promoters. In addition, the enrichment of DNMT1 in the Glis2 promoter region was mediated by metastasis-associated lung adenocarcinoma transcriptor-1 (MALAT1) lncRNA, leading to transcriptional silencing of Glis2 and activation of HSCs. In conclusion, our findings reveal that the upregulation of Glis2 can maintain the resting state of HSCs. The decreased expression of Glis2 under pathological conditions may lead to the occurrence and development of HF with the expression silencing of DNA methylation mediated by MALAT1 and DNMT1.

Quantitative Assessment of the Diagnostic Role of CDH13 Promoter Methylation in Lung Cancer

Zhong, Yun-Hua,Peng, Hao,Cheng, Hong-Zhong,Wang, Ping Asian Pacific Journal of Cancer Prevention 2015 Asian Pacific journal of cancer prevention Vol.16 No.3

In order to explore the association between cadherin 13 (CDH13) gene promoter methylation and lung carcinoma (LC) risk, we carried out a meta-analysis with searching of PubMed, Web of Science. Ultimately, 17 articles were identified and analysised by STATA 12.0 software. Overall, we found a significant relationship between CDH13 promoter methylation and LC risk (odds ratio=6.98, 95% confidence interval: 4.21-11.56, p<0.001). Subgroup analyses further revealed that LC risk was increased for individuals carrying the methylated CDH13 compared with those with unmethylated CDH13. Hence, our study identified a strong association between CDH13 gene promoter methylation and LC and highlighted a promising potential for CDH13 methylation in LC risk prediction.

Dynamic Modeling and Accuracy Evaluation Method for Complex Special-Shaped Components of Aviation Transmission

Aiqiang Zhang,Jing Wei,Hao Cheng,Bin Peng,Miaofei Cao 한국정밀공학회 2022 International Journal of Precision Engineering and Vol.23 No.11

Due to designers' demanding pursuit of high power-to-weight ratio, most components in aviation transmission, including casing and shafting, are designed as special-shaped thin-walled structures. The assumption of large stiffness is no longer applicable. The casing is rich in geometric features and is usually modeled by the finite element (FE) method. However, the huge number of degrees of freedom (DOFs) poses great challenges to dynamic design. Model condensation provides an effective method for matrix dimensionality reduction. Taking the case of a helicopter main reducer as an example, a dynamic modeling method based on experimental modal analysis-FE method-substructure condensation is proposed. In addition, a method for measuring condensation errors is proposed to help determine the minimum number of nodes and their most suitable locations. Finally, the condensed models with the minimum number of nodes which meet the accuracy requirements are obtained. In previous studies, beam elements were usually used to simulate shafting flexibility, but the number of nodes and model accuracy were rarely discussed. And the selection of beam elements has not yet been unified. The optimal combination of beam element stiffness and mass matrix is determined based on regular shafting. Furthermore, the applicability of beam element method and condensation method in shafting modeling with different degree of regularity is compared. The research provides substructure models considering both accuracy and calculation efficiency for the overall system modeling of the aviation transmission.

Discrimination of neutrons and gamma-rays in plastic scintillator based on spiking cortical model

Liu Bing-Qi,Liu Hao-Ran,Chang Lan,Cheng Yu-Xin,Zuo Zhuo,Li Peng 한국원자력학회 2023 Nuclear Engineering and Technology Vol.55 No.9

In this study, a spiking cortical model (SCM) based n-g discrimination method is proposed. The SCMbased algorithm is compared with three other methods, namely: (i) the pulse-coupled neural network (PCNN), (ii) the charge comparison, and (iii) the zero-crossing. The objective evaluation criteria used for the comparison are the FoM-value and the time consumption of discrimination. Experimental results demonstrated that our proposed method outperforms the other methods significantly with the highest FoM-value. Specifically, the proposed method exhibits a 34.81% improvement compared with the PCNN, a 50.29% improvement compared with the charge comparison, and a 110.02% improvement compared with the zero-crossing. Additionally, the proposed method features the second-fastest discrimination time, where it is 75.67% faster than the PCNN, 70.65% faster than the charge comparison and 38.4% slower than the zero-crossing. Our study also discusses the role and change pattern of each parameter of the SCM to guide the selection process. It concludes that the SCM's outstanding ability to recognize the dynamic information in the pulse signal, improved accuracy when compared to the PCNN, and better computational complexity enables the SCM to exhibit excellent n-g discrimination performance while consuming less time.

Observation of multi-channel non-local transport in J-TEXT plasmas

Shi, Yuejiang,Chen, Zhongyong,Yang, Zhoujun,Shi, Peng,Zhao, Kaijun,Diamond, Patrick H.,Kwon, JaeMin,Yan, Wei,Zhou, Hao,Pan, Xiaoming,Cheng, Zhifeng,Chen, Zhiping,Yang, SeongMoo,Zhang, Chi,Li, Da,Dong, IOP 2018 Nuclear fusion. Fusion nucléaire. &n.Illiga Vol.58 No.4

<P>In cold pulse experiments in J-TEXT, not only are rapid electron temperature increases in the core observed, but also steep rises in the inner density are found. Moreover, some evidence of acceleration of the core toroidal rotation is also observed during the non-local transport process of electron temperature. These new findings of cold pulse experiments in J-TEXT suggest that turbulence spreading is a possible mechanism for the non-local transport dynamics.</P>

Moderately Hypofractionated Conformal Radiation Treatment of Thoracic Esophageal Carcinoma

Ma, Jin-Bo,Wei, Lin,Chen, Er-Cheng,Qin, Guang,Song, Yi-Peng,Chen, Xiang-Ming,Hao, Chuan-Guo Asian Pacific Journal of Cancer Prevention 2012 Asian Pacific journal of cancer prevention Vol.13 No.8

Aims: To prospectively assess the efficacy and safety of moderately hypofractionated conformal radiotherapy in patients with thoracic esophageal cancer. Methods and Materials: From Sept. 2002 to Oct, 2005, 150 eligible patients with T2-4N0-1M0 stage thoracic esophageal squamous cell cancers were enrolled to receive either conventional fractionated radiation (CFR) or moderately hypofractionated radiation (MHR) with a three-dimensional conformal radiation technique. Of the total, 74 received moderately hypofractionated radiation with total dose of 54-60Gy/18-20fractions for 3.5-4 weeks in the MHR arm, and 76 received conventional radiation with total dose of 60Gy/30 fractions for 6 weeks in the CFR arm. Concurrent chemotherapy comprised of paclitaxel and cisplatin. Safety was evaluated, and local control and overall survival rates were calculated. Results: Statistically significant differences between the CFR versus MHR arms were observed in local/regional failure rate (47.3% v 27.0%, P=0.034) and the percentage of patients with persistent local disease (26.3% v 10.8%, P=0.012). But 3 and 5-year overall survival rates (43.2%, 38.8% v 38.2%, 28.0%, respectively) were not different between the two arms (P=0.268). There were no significant differences in the incidences of grade 3 or higher acute toxicities (66.3% v 50.0%) and late complications rates (27.0% v 22.4%) between the MHR and CFR arms. Conclusions: Moderately hypofractionated, three-dimensional radiation treatment could improve the local control rate of esophageal cancer and potentially increase patients' survival.

Association of DNA Base-excision Repair XRCC1, OGG1 and APE1 Gene Polymorphisms with Nasopharyngeal Carcinoma Susceptibility in a Chinese Population

Li, Qing,Wang, Jian-Min,Peng, Yu,Zhang, Shi-Heng,Ren, Tao,Luo, Hao,Cheng, Yi,Wang, Dong Asian Pacific Journal of Cancer Prevention 2013 Asian Pacific journal of cancer prevention Vol.14 No.9

Background: Numerous carcinogens and reactive oxygen species (ROS) may cause DNA damage including oxidative base lesions that lead to risk of nasopharyngeal carcinoma. Genetic susceptibility has been reported to play a key role in the development of this disease. The base excision repair (BER) pathway can effectively remove oxidative lesions, maintaining genomic stability and normal expression, with X-ray repair crosscomplementing1 (XRCC1), 8-oxoguanine glycosylase-1 (OGG1) and apurinic/apyimidinic endonuclease 1 (APE1) playing important roles. Aims: To analyze polymorphisms of DNA BER genes (OOG1, XRCC1 and APE1) and explore their associations, and the combined effects of these variants, with risk of nasopharyngeal carcinoma. Materials and Methods: We detected SNPs of XRCC1 (Arg399Gln), OGG1 (Ser326Cys), APE1 (Asp148Glu and -141T/G) using the polymerase chain reaction (PCR) with peripheral blood samples from 231 patients with NPC and 300 healthy people, furtherly analyzing their relations with the risk of NPC in multivariate logistic regression models. Results: After adjustment for sex and age, individuals with the XRCC1 399Gln/Gln (OR=1.96; 95%CI:1.02-3.78; p=0.04) and Arg/Gln (OR=1.87; 95%CI:1.29-2.71; p=0.001) genotype variants demonstrated a significantly increased risk of nasopharyngeal carcinoma compared with those having the wild-type Arg/Arg genotype. APE1-141G/G was associated with a significantly reduced risk of NPC (OR=0.40;95%CI:0.18-0.89) in the smoking group. The OR calculated for the combination of XRCC1 399Gln and APE1 148Gln, two homozygous variants, was significantly additive for all cases (OR=2.09; 95% CI: 1.27-3.47; p=0.004). Conclusion: This is the first study to focus on the association between DNA base-excision repair genes (XRCC1, OGG1 and APE1) polymorphism and NPC risk. The XRCC1 Arg399Gln variant genotype is associated with an increased risk of NPC. APE1-141G/G may decrease risk of NPC in current smokers. The combined effects of polymorphisms within BER genes of XRCC1 399Gln and APE1 148Gln may contribute to a high risk of nasopharyngeal carcinoma.