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.

Chemical Compositions and Antimicrobial Activities of Essential Oils Extracted from Acanthopanax brachypus

Hu Haobin,Zheng Xudong,Hu Huaisheng,Li Yan 대한약학회 2009 Archives of Pharmacal Research Vol.32 No.5

The essential oils from the flowers, leaves, barks, roots and fruits of A. brachypus were individually extracted by hydrodistillation, and their chemical constituents were isolated and characterized by means of gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). A total of 160 different constituents accounting for 86.45-96.54% of the total essential oils were identified, and 3 constituents were unidentified (< 0.8%), and significant qualitative and quantitative differences were observed among the oils, in which the yields varied between 0.61-1.83 (mL/100 g dried materials) under the same operational conditions. The oils from flowers, leaves, barks and roots consisted mainly of monoterpenes and sesquiterpene hydrocarbons as well as oxygenated monoterpenes and sesquiterpenes, while the fruit oil consisted mainly of fatty acids and esters. The antimicrobial activities of the essential oils was evaluated against 11 microorganisms (9 for bacteria and 2 for yeast) using agar disc diffusion and broth microdilution methods. The bacteria, including gram-positive bacteria and gramnegative bacteria, were more sensitive to the oils than yeasts.

THE MODERATING ROLE OF AGE: THE IMPACT OFWEBSITE INTERACTIVITY ON BRAND DEVELOPMENT IN CHINESE OTA WEBSITES

Ben Haobin,Albert A. Barreda,Khaldoon Nusair,Fevzi Okumus 글로벌지식마케팅경영학회 2016 Global Marketing Conference Vol.2016 No.7

The aim of the present study is to propose a model to examine the relationships among social Website interactivity, brand experience, brand choice, and behavioral intentions in the context of online travel agencies brand websites, as well as to examine the ultimate moderating role of the age of the traveler in the dynamic of this model. Drawing on website interactivity and brand development theories, current research suggests that the inclusion of social website interactivity in the design of online travel agencies brand websites helps to directly and indirectly create a positive brand experience and to enhance the perception of online travel agencies brand websites as valuable. These perceptions may consequently impact the behavior of travelers to pay higher prices and to continue buying from the online travel agencies brand websites. However, while this existent research mostly considers the positive and causal relationships among the aforementioned constructs, there is also some indication that the perceptions of travelers in relation to the proposed relationships change with age, suggesting that older travelers (age above 25) may perceive distinctively the relationships among these constructs in the context of online travel agencies brand websites as compared to younger travelers (aged 18-25). The study attempts to analyze on this relevant and under-examined research topic. This research is mainly based on a sample of travelers who have used an online travel agencies brand websites in China. The empirical findings suggest that social website interactivity, brand experience, and brand choice are essential factors for travelers to be willing to pay higher prices and to continue buying. The empirical findings also suggest that the proposed theoretical framework is adequately adjusted, therefore confirming that the age of the traveler moderates the proposed relationships first between social website interactivity and brand choice, second between brand choice and price premium, third between brand choice and buying intention, and lastly between brand experience and buying intention. Overall, the theory-driven framework accomplishes an acceptable model fit. Additionally, theoretical and practical implications are discussed. Social Website Interactivity (SWI) construct is defined as the reciprocal communication between individuals and technology. Research shows that SWI exerts a positive impact on the user that eventually causes an e-loyal behavior (Cyr et al., 2010). Voorveld et al. (2009) conclude the design of a theoretical model that includes SWI and branding elements is required to brand Websites. The theory explains SWI as a branding tool and its influence on travelers’ perceptions and behaviors in the travel context. Given these findings, the authors of this study predict that OTA Websites that incorporate features of SWI may have a remarkable competence to build a brand online. Based on the given review, it is rational to expect that SWI might influence user perceptions of value and positive brand experience of the OTA branded website. A favorable experience is what reduces perceived risks when buying online and what influences users to revisit the website. Brand selection and brand experience (Morgan-Thomas & Veloutsou, 2013) are key elements to influence consumers’ behavior therefore must have a significant influence on behavioral intentions and willingness to pay premium prices. The current perception in social sciences and behavioral marketing is that age is a critical demographic variable that has direct and moderating role in the impact of interactivity and brand selection, brand selection and willingness to pay higher prices, brand selection and behavioral intentions, and online experience on behavioral intentions (Kirk et al., 2012).

Human Cytomegalovirus IE1-72 Protein Interacts with p53 and Inhibits p53-Dependent Transactivation by a Mechanism Different from That of IE2-86 Protein

Hwang, Eung-Soo,Zhang, Zhigang,Cai, Haobin,Huang, David Y.,Huong, Shu-Mei,Cha, Chang-Yong,Huang, Eng-Shang American Society for Microbiology 2009 Journal of virology Vol.83 No.23

<B>ABSTRACT</B><P>Infection of host cells with human cytomegalovirus (HCMV) induces cell cycle dysregulation. Two HCMV immediate-early (IE) proteins, IE1-72 and IE2-86, are promiscuous transactivators that have been implicated in the dysregulatory events. Cellular p53 protein is accumulated to high levels in HCMV-infected cells, but the indicative marker of p53 transcriptional activity, p21, is markedly decreased. Both IE1-72 and IE2-86 were able to transactivate the p53 promoter and interact with p53 protein in DNA-transfected or HCMV-infected cells. HCMV UL84, a multiregulatory protein expressed in early periods of HCMV infection, also interacted with p53. HCMV IE1-72 prevented or disrupted p53 binding to p53-specific DNA sequences, while IE2-86 and/or UL84 enhanced p53 binding and induced supershift of this DNA-protein complex. Both HCMV IE1-72 and IE2-86 were able to inhibit p53-dependent transcriptional activation in plasmid-transfected cells. IE1-72, rather than IE2-86, was found to be responsible for p21 downregulation in HCMV-infected HEL cells. DNA transfection analysis using IE1-72 mutants revealed that exon 2/3 and the zinc finger region of IE1-72 are essential for IE1-72's effect on the repression of p53-dependent transcriptional activation. These data suggest that HCMV IE1-72 and/or IE2-86 transactivates the p53 promoter and induces p53 accumulation, but HCMV IE1-72 represses the p53 transactivation activity by a unique binding hindrance mechanism different from that of IE2-86. Thus, various modes of viral IE proteins and p53 interactions might result in multiple outcomes, such as stimulation of cellular DNA synthesis, cell cycle progression and cell cycle arrest, and prevention of program cell death.</P>

Genetic homogeneity between populations of cotton bollworm from Xinjiang, China

Dongmei Wang,Xianming Yang,Haiqiang Li,Akedan Wuwaishi,Ruifeng Ding,Haobin Li,Hongsheng Pan,Jian Liu,Yao Xu,Yan-Hui Lu 한국응용곤충학회 2018 Journal of Asia-Pacific Entomology Vol.21 No.1

We studied the population structure of cotton bollworm (CBW), Helicoverpa armigera (Hübner) (Lepidoptera:Noctuidae), in Xinjiang, the largest cotton-growing region in China, using a fragment of cytochrome c oxidasesubunit I (COI) gene. Alignments of all 192 COI sequences revealed 28 haplotypes including 23 in southernXinjiang, 5 in eastern Xinjiang and 13 in northern Xinjiang. Negative and significant values of neutrality tests forthe Tajima's D and Fu's FS parameters, combined with the high values of haplotype diversity (Hd), low values ofnucleotide diversity (π) and a high number of low frequency haplotypes indicated a recent demographic expansionof Xinjiang CBW populations. Analysis of molecular variation (AMOVA) indicated low and non-significantgenetic structure, regardless of geographical scale or crop, with most of genetic variation occurringwithin local CBW populations. Pairwise FST analyses also indicated low genetic differentiation. This demographicevent and high gene flow could be responsible for the low genetic structure currently found. CBW populations inXinjiang need to be considered as one panmictic unit in its management, especially for the design of refuges todelay the development of resistance by this migratory pest to transgenic Bt (Bacillus thuringiensis) cotton.