Complete loss distribution model of GaN HEMTs considering the influence of parasitic parameters

Shengwei Gao,Jinrui Tian,Xiaoyu Fu,Yongxiao Li,Bo Wang,Lixia Zhao 전력전자학회 2024 JOURNAL OF POWER ELECTRONICS Vol.24 No.1

When compared with Si-based devices, Gallium Nitride High Electron Mobility Transistors (GaN HEMTs) possess the advantages of lower junction-to-case thermal resistance, smaller on-state resistance, faster switching velocity, and higher switching frequency. These advantages make them a promising power semiconductor device. However, with the enhancement of switching frequencies, the influence of parasitic parameters on switching ringing and the losses of GaN HEMTs are increasingly severe. Thus, it is necessary to predict the loss distribution by establishing an accurate loss model of the switching process. On the premise of considering parasitic inductance, nonlinear junction capacitance, and reverse transfer characteristics, this article proposes a precise switching loss model of GaN HEMTs to predict the loss distribution in the switching process. In addition, it verifies results based on the double pulse test (DPT) circuit, which validates the accuracy of the proposed model. Ultimately, based on the above-mentioned loss model, this article discussed the influence of parasitic capacitance and inductance on the output capacitance loss (Eqoss), the reverse conduction loss (ESD), the opening V-I overlap loss (Eopen), the closing V-I overlap loss (Eclose), and the total loss (Etotal). Then, this article produces an optimizing method to enhance the conversion efficiency of GaN HEMTs in accordance with laboratory findings.

Analysis of the fluid-solid-thermal coupling of a pressurizer surge line under ocean conditions

Yu Hang,Zhao Xinwen,Fu Shengwei,Zhu Kang 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.10

To investigate the effects of ocean conditions on the thermal stress and deformation caused by thermal stratification of a pressurizer surge line in a floating nuclear power plant (FNPP), the finite element simulation platform ANSYS Workbench is utilized to conduct the fluid-solid-thermal coupling transient analysis of the surge line under normal “wave-out” condition (no motion) and under ocean conditions (rolling and pitching), generating the transient response characteristics of temperature distribution, thermal stress and thermal deformation inside the surge line. By comparing the calculated results for the three motion conditions, it is found that ocean conditions can significantly improve the thermal stratification phenomenon within the surge line, but may also result in periodic oscillations in the temperature, thermal stress, and thermal deformation of the surge line. Parts of the surge line that are more susceptible to thermal fatigue damage or failure are determined. According to calculation results, the improvements are recommended for pipeline structure to reduce the effects of thermal oscillation caused by ocean conditions. The analysis method used in this study is beneficial for designing and optimizing the pipeline structure of a floating nuclear power plant, as well as for increasing its safety.

Single nucleotide polymorphism-based analysis of the genetic structure of the Min pig conserved population

Meng Fanbing,Cai Jiancheng,Wang Chunan,Fu Dechang,Di Shengwei,Wang Xibiao,Chang Yang,Xu Chunzhu 아세아·태평양축산학회 2022 Animal Bioscience Vol.35 No.12

Objective: The study aims to uncover the genetic diversity and unique genetic structure of the Min pig conserved population, divide the nucleus conservation population, and construct the molecular pedigree. Methods: We used KPS Porcine Breeding Chip v1 50K for SNP detection of 94 samples (31♂, 63♀) in the Min pig conserved population from Lanxi breeding Farm. Results: The polymorphic marker ratio (PN), the observed heterozygosity (Ho), and the expected heterozygosity (He) were 0.663, 0.335, and 0.330, respectively. The pedigreebased inbreeding coefficients (FPED) was significantly different from those estimated from runs of homozygosity (FROH) and single nucleotide polymorphism (FSNP) based on genome. The Pearson correlation coefficient between FROH and FSNP was significant (p<0.05). The effective population content (Ne) showed a continuously decreasing trend. The rate of decline was the slowest from 200 to 50 generations ago (r = 0.95), then accelerated slightly from 50 to 5 generations ago (1.40<r<1.50) and increased significantly in the last 5 generations (r = 2.6). According to the composition of Chinese lineage, we separated the nucleus conservation population (81 individuals) and the candidate conservation population (13 individuals) of Min pig, then the nucleus conservation population of Min pig was divided into 9 families by genomic information matrix. Conclusion: Our study indicated that the genetic diversity of the Min pig conserved population was inadequate. Due to the introgression of European commercial pig breeds and the unscientific breeding process, it is necessary to construct the molecular pedigree of the nucleus conservation population for the Min pig. Objective: The study aims to uncover the genetic diversity and unique genetic structure of the Min pig conserved population, divide the nucleus conservation population, and construct the molecular pedigree.Methods: We used KPS Porcine Breeding Chip v1 50K for SNP detection of 94 samples (31♂, 63♀) in the Min pig conserved population from Lanxi breeding Farm.Results: The polymorphic marker ratio (PN), the observed heterozygosity (Ho), and the expected heterozygosity (He) were 0.663, 0.335, and 0.330, respectively. The pedigree-based inbreeding coefficients (F_PED) was significantly different from those estimated from runs of homozygosity (F_ROH) and single nucleotide polymorphism (FSNP) based on genome. The Pearson correlation coefficient between F_ROH and F_SNP was significant (p<0.05). The effective population content (Ne) showed a continuously decreasing trend. The rate of decline was the slowest from 200 to 50 generations ago (r = 0.95), then accelerated slightly from 50 to 5 generations ago (1.40<r<1.50) and increased significantly in the last 5 generations (r = 2.6). According to the composition of Chinese lineage, we separated the nucleus conservation population (81 individuals) and the candidate conservation population (13 individuals) of Min pig, then the nucleus conservation population of Min pig was divided into 9 families by genomic information matrix.Conclusion: Our study indicated that the genetic diversity of the Min pig conserved population was inadequate. Due to the introgression of European commercial pig breeds and the unscientific breeding process, it is necessary to construct the molecular pedigree of the nucleus conservation population for the Min pig.

A Potent Brucella abortus 2308 Δery Live Vaccine Allows for the Differentiation between Natural and Vaccinated Infection

Junbo Zhang,Shuanghong Yin,Fei Guo,Ren Meng,Chuangfu Chen,Hui Zhang,Zhi-qiang Li,Qiang Fu,Huijun Shi,Shengwei Hu,Wei Ni,Tiansen Li,Ke Zhang 한국미생물학회 2014 The journal of microbiology Vol.52 No.8

Brucellosis is a globally distributed zoonotic disease that causes animal and human diseases. However, the current Brucella abortus vaccines (S19 and RB51) are deficient; they can cause abortion in pregnant animals. Moreover, when the vaccine S19 is used, tests cannot differentiate natural from vaccinated infection. Therefore, a safer and more potent vaccine is needed. A Brucella abortus 2308 ery promoter mutant (Δery) was constructed to overcome these drawbacks. The growth of the Δery mutant was significantly attenuated in macrophages and mice and induced high protective immunity in mice. Moreover, Δery induced an anti-Brucellaspecific IgG (immunoglobulin G) response and stimulated the expression of interferon-gamma (INF-γ) and interleukin-4 (IL-4). Furthermore, the expression of EryA antigen allowed for the serological differentiation between natural and vaccinated infection in mice. These results indicate that the Δery mutant is a potential attenuated live vaccine candidate against virulent Brucella abortus 2308 (S2308) infection.