Vortex dynamic characteristics of unsteady tip clearance cavitation in a waterjet pump determined with different vortex identification methods

Shun Xu,Xin-ping Long,Bin Ji,Gui-bin Li,Tao Song 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.12

The cavitating flow field in waterjet pumps is complex, especially tip leakage cavitation (TLC), which has been a puzzle to researchers for decades. In this study, high-speed video (HSV) of the instantaneous inner structures of tip cavitation flow is used to show the evolution of TLC. Numerical simulation is conducted with the scale adaptive simulation (SAS) turbulence model and Zwart-Gerber-Belamri (ZGB) cavitation model to understand the cavitation-vortex interaction in the blade tip region. The predicted cavitation performance curve exhibits reasonable agreement with the experimental results, and the time-dependent vapor iso-surfaces (α v = 0.1) are consistent with HSV at different times in a typical cycle. Numerical simulation results show that cavitation can enhance the turbulent kinetic energy in the unstable vortex cavitation region and downstream tip leakage vortex region along the blade. Different vortex identification methods, including vorticity, Q criterion, λ ci , λ 2 criterion, Ω, and Liutex/Rortex, are investigated. Analysis and comparison of the iso-surfaces of the different vortex identification methods indicate that the Ω and Liutex iso-surfaces can effectively predict the tip leakage vortex core and vortex pair in the unstable vortex cavitation region. Analysis of the fifth clip contours shows that no obvious difference exists between Q and λ 2 criteria in terms of predicting the vortex core. All vortex identification methods can accurately predict the tip separation vortex in the blade tip region, but only the Ω and Liutex iso-surfaces can predict weak vortices in the cavitation region. The influence of the small parameter ε of the Ω method on tip vortex identification is also discussed.

Parallel Tempering Simulation on Generalized Canonical Ensemble

Xu, Shun,Zhou, Xin,Ou-Yang, Zhong-Can Global Science Press 2012 Communications in computational physics Vol.12 No.5

<B>Abstract</B><P>Parallel tempering simulation is widely used in enhanced sampling of systems with complex energy surfaces. We hereby introduce generalized canonical ensemble (GCE) instead of the usual canonical ensemble into the parallel tempering to further improve abilities of the simulation technique. GCE utilizes an adapted weight function to obtain a unimodal energy distribution even in phase-coexisting region and then the parallel tempering on GCE yields the steady swap acceptance rates (SARs) instead of the fluctuated SARs in that on canonical ensemble. With the steady SARs, we can facilitate assign the parameters of the parallel tempering simulation to more efficiently reach equilibrium among different phases. We illustrate the parallel tempering simulation on GCE in the phase-coexisting region of 2-dimensional Potts model, a benchmark system for new simulation method developing. The result indicates that the new parallel tempering method is more efficient to estimate statistical quantities (i.e., to sample the conformational space) than the normal parallel tempering, specially in phase-coexisting regions of larger systems.</P>

The role and mechanism of lncRNA NEAT1 in the fibrosis of pulmonary epithelial cell

Hui Xu,YanBo Chen,Jinqiang Zhuang,Shun Zhu,Bing Xu,Jiang Hong 대한독성 유전단백체 학회 2020 Molecular & cellular toxicology Vol.16 No.2

Background Pulmonary fibrosis is a serious clinical fatal disease. Epithelial–mesenchymal transition (EMT) and lncRNA NEAT1 have been implied in its development and progression. Objective To study the role of lncRNA NEAT1 in the progression of fibrosis in human pulmonary epithelial cells (BEAS- 2B). Specifically, BEAS-2B was transfected with NEAT1 and miR-29c, EMT and cell proliferation were measured and the expression level of relevant genes was determined by Western blot. Result Results showed that NEAT1 promotes fibrosis and proliferation of BEAS-2B cells via the up-regulation of α-SMA, Vimentin, Snail and proliferation-related genes including Cyclin D1 and Cyclin E; miR-29c is a target gene of NEAT1 and through which NEAT1 regulates EMT and expression of proliferation-related genes. Conclusion This study investigated the mechanism of pulmonary fibrosis progression by elucidating the role of NEAT1/ miR-29c in the fibrosis and proliferation of BEAS-2B cells, thus providing a basis for the new therapeutic targets of pulmonary fibrosis.

Research Cage Wind Turbines’ Dynamic Characteristics Based on Time-varying Parameters

Gu Bo,Liu Yongqian,Xu Qiang,Kang Shun 보안공학연구지원센터 2014 International Journal of Control and Automation Vol.7 No.10

According to the characteristics of cage wind turbines’ dynamic characteristics which change following the wind speed changes, the dynamic mathematical models of cage wind turbines major subsystems have been established, including the aerodynamic subsystem model, drive train subsystem model and generator subsystem model. Then these nonlinear dynamic models with time-varying parameters have been integrated and linearized to obtain the whole linear time-varying parameters dynamic mathematical model. To take the 2MW cage wind turbines wind turbine as example, the proposed model is validated by the study on the dynamic characteristics of cage wind turbines with wind speed variation , and the results show that the proposed model could provide a theoretical support for optimal control of the cage wind turbines.

Hyperglycemia Influences Apoptosis and Autophagy in Porcine Parthenotes Developing In Vitro

Xu, Yong-Nan,Li, Ying-Hua,Lee, Sung Hyun,Kwon, Jung-Woo,Lee, Seul Ki,Heo, Young-Tae,Cui, Xiang-Shun,Kim, Nam-Hyung The Korean Society of Animal Reproduction 2013 Reproductive & developmental biology Vol.37 No.2

The objective of this study was to examine the effects of high concentrations of glucose on porcine parthenotes developing in vitro. Addition of 55 mM glucose to the culture medium of embryos at the four-cell-stage significantly inhibited blastocyst formation, resulting in fewer cells in blastocyst-stage embryos and increased levels of apoptosis and autophagy compared to control. Quantitative reverse transcriptase (RT) PCR analysis revealed that the expression of pro-apoptotic genes (Caspase 3, Bax and Bak) and autophagy genes (Atg6 and Atg8/Lc3) were increased significantly by the addition of 55 mM glucose to the culture medium compared to control. MitoTracker Green fluorescence revealed a decrease in the overall mitochondrial mass compared to control. However, the addition of 55 mM glucose had no effect on mRNA expression of the nuclear DNA-encoded mitochondrial-related genes, cytochrome oxidase (Cox) 5a, Cox5b and Cox6b1. These results suggest that hyperglycemia reduced the mitochondrial content of porcine embryos developing in vitro and that this may hinder embryonic development to the blastocyst stage and embryo quality by increasing apoptosis and autophagy in these embryos.

Characterization of a Novel cry1-Type Gene from Bacillus thuringiensis subsp. alesti Strain LY-99

Xu Feng Qi,Ming Shun Li,Jae Young Choi,Jong Yul Roh,Ji Zhen Song,Yong Wang,Byung Rae Jin,Yeon Ho Je,Jian Hong Li 한국잠사학회 2009 International Journal of Industrial Entomology Vol.18 No.1

B. thuringiensis strain LY-99 belonging to subsp. Alesti (H3a3c), was isolated from Chinese tobacco warehouse and showed significantly high toxicity to Plutella xylostella. For the identification of the cry1-type genes from B. thuringiensis LY-99, an extended multiplex PCR-restriction fragment length polymorphism (PCR-RFLP) method was established by using two pairs of universal primers based on the conserved regions of the cry1-type genes to amplify around 2.4 kb cry1-type gene fragments. Then the DNA fragment was cloned into pGEM-T Easy vector and digested with EcoRI and EcoRV enzymes. Through this method, a known cry1-type gene was successfully identified from the reference strain, B. thuringiensis subsp. alesti. In addition, the RFLP patterns revealed that B. thuringiensis LY-99 included a novel cry1A-type gene in addition to cry1Aa, cry1Ac, cry1Be and cry1Ea genes. The novel cry1A-type gene was designated cry1Ah2 (Genbank accession No DQ269474). An inverse PCR method was used to amplify the flank regions of cry1Ah2 gene. Finally, 3143 bp HindIII fragment from B. thuringiensis LY-99 plasmid DNA including 5` region and partial ORF was amplified, and sequence analysis revealed that cry1Ah2 gene from LY-99 showed 89.31% of maximum sequence similarity with cry1Ac1 crystal protein gene. In addition, the deduced amino acid sequence of Cry1Ah2 protein shared 87.80% of maximum identity with that of Cry1Ac2. This protein therefore belongs to a new class of B. thuringiensis crystal proteins.

Apoptosis induced in vivo by new type gosling viral enteritis virus

Shun Chen,Anchun Cheng,Mingshu Wang,Dekang Zhu,Renyong Jia,Qihui Luo,Hengmin Cui,Yi Zhou,Yin Wang,Zhiwen Xu,Zhengli Chen,Xiaoyue Chen,Xiaoyu Wang 대한수의학회 2011 JOURNAL OF VETERINARY SCIENCE Vol.12 No.4

In this study, apoptosis was induced by new type gosling viral enteritis virus (NGVEV) in experimentally infected goslings is reported in detail for the first time. After 3-day-old goslings were orally inoculated with a NGVEV-CN strain suspension, the time course of NGVEV effects on apoptotic morphological changes of the internal tissues was evaluated. These changes were observed by histological analysis with light microscopy and ultrastructural analysis with transmission electron microscopy. DNA fragmentation was assessed with a terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL) assay and DNA ladder analysis. A series of characteristic apoptotic morphological changes including chromatin condensation and margination, cytoplasmic shrinkage, plasma membrane blebbing, and formation of apoptotic bodies were noted. Apoptosis was readily observed in the lymphoid and gastrointestinal organs, and sporadically occurred in other organs after 3 days post-infection (PI). The presence and quantity of TUNEL-positive cells increased with infection time until 9 days PI. DNA extracted from the NGVEV-infected gosling cells displayed characteristic 180~200 bp ladders. Apoptotic cells were ubiquitously distributed, especially among lymphocytes, macrophages, monocytes, and epithelial and intestinal cells. Necrosis was subsequently detected during the late NGVEV-infection phase, which was characterized by cell swelling, plasma membrane collapse, and rapidly lysis. Our results suggested that apoptosis may play an important role in the pathogenesis of NGVE disease.

Autophagy influences maternal mRNA degradation and apoptosis in porcine parthenotes developing in vitro.

Xu, Yong-Nan,Shen, Xing-Hui,Lee, Seung-Eun,Kwon, Jung-Suk,Kim, Deuk-Joong,Heo, Young-Tae,Cui, Xiang-Shun,Kim, Nam-Hyung Japanese Society of Animal Reproduction 2012 The Journal of reproduction and development Vol.58 No.5

<P>Autophagy, an essential process for cellular maintenance, cell viability, and development, is the bulk degradation of proteins and organelles. This study investigated the expression levels of autophagy-related genes and the effect of 3-methyladenine (3-MA, an autophagy inhibitor) or rapamycin (an autophagy inducer) on maternal gene degradation and apoptosis in porcine parthenotes developing in vitro. LC3, which is essential for the formation of autophagosomes, was widely expressed in porcine parthenotes. High levels of autophagy-related genes, Atg5, Beclin1 and Lc3 transcripts were expressed in the 1-cell (1C) stage and gradually decreased through the 2-cell (2C) to blastocyst stages. The mRNA expression of Gdf9, c-mos and cyclin B maintained high levels in 2C and 4-cell (4C) embryos treated with 3-MA compared with the control. The Bmp15 and cyclin B mRNA levels were significantly reduced in embryos treated with rapamycin compared with the control. These results suggest that autophagy influences the degradation of these maternal genes. Furthermore, 3-MA-treated embryos exhibited significantly reduced developmental rates, decreased total cell numbers and increased rates of apoptosis. Expression of Atg5, Beclin1 and Lc3 and synthesis of LC3 protein were significantly reduced at the blastocyst stage. Although rapamycin treatment did not affect the developmental rate, it decreased the cell number and increased the rate of apoptosis, and the expression of Atg5, Beclin1 and Lc3 and LC3 protein synthesis were increased. Finally, blastocysts derived following treatment with 3-MA or rapamycin exhibited significantly decreased expression of selected transcription factors, including Pou5f1, Sox2 and Nanog. In conclusion, our results demonstrate that autophagy influences maternal mRNA degradation and apoptosis at the blastocyst stage and suggest that autophagy plays an important role in early embryo development in the pig.</P>

Novel reduced-order modeling method combined with three-particle nonlinear transform unscented Kalman filtering for the battery state-of-charge estimation

Xu, Wenhua,Wang, Shunli,Fernandez, Carlos,Yu, Chunmei,Fan, Yongcun,Cao, Wen The Korean Institute of Power Electronics 2020 JOURNAL OF POWER ELECTRONICS Vol.20 No.6

Accurate estimation of the lithium-ion battery state of charge plays an important role in the real-time monitoring and safety control of batteries. In order to solve the problems that the real-time estimation of the lithium-ion battery is difficult and the estimation accuracy is not high under various working conditions, a lithium-ion battery is taken as a research object, and the working characteristics of the lithium-ion battery are studied under various working conditions. In order to reduce the computational complexity of the traditional unscented Kalman algorithm, an improved unscented Kalman algorithm is proposed. Considering the importance of accurately estimating the initial state of charge for later estimation, the initial estimation value is calibrated by using the open-circuit voltage method. Then, the improved unscented Kalman filter algorithm based on a reduced-order model is used for assessing and tracking to realize real-time high-precision estimation of the state of charge of the lithium-ion battery. A simulation model is built and combined with a variety of working conditions data for performance analysis. The experimental results show that the convergence speed and tracking effect are good and that the estimation error control is within 0.8%. It is verified that the reduced order of the three-particle nonlinear transform unscented Kalman results in higher accuracy in the state-of-charge estimation of lithium-ion batteries.

Thermal and Moisture Behavior of wood Columns Exposed in Outdoor Environment

( Shun Ji Pan ),( Hui Lan Xu ),( Woo Yang Chung ),( Wook Kang ) 韓國木材工學會 2008 한국목재공학회 학술발표논문집 Vol.2008 No.-