Field measurement and CFD simulation of wind pressures on rectangular attic

Yongbo Peng,Weijie Zhao,Xiaoqiu Ai 한국풍공학회 2019 Wind and Structures, An International Journal (WAS Vol.29 No.6

Wind pressure is a critical argument for the wind-resistant design of structures. The attempt, however, to explore the wind pressure field on buildings still encounters challenges though a large body of researches utilizing wind tunnel tests and wind field simulations were carried out, due to the difficulty in logical treatments on the scale effect and the modeling error. The full-scale measurement has not yet received sufficient attention. By performing a field measurement, the present paper systematically addresses wind pressures on the rectangular attic of a double-tower building. The spatial and temporal correlations among wind speed and wind pressures at measured points are discussed. In order to better understand the wind pressure distribution on the attic facades and its relationship against the approaching flow, a full-scale CFD simulation on the similar rectangular attic is conducted as well. Comparative studies between wind pressure coefficients and those provided in wind-load codes are carried out. It is revealed that in the case of wind attack angle being zero, the wind pressure coefficient of the cross-wind facades exposes remarkable variations along both horizontal and vertical directions; while the wind pressure coefficient of the windward facade remains stable along horizontal direction but exposes remarkable variations along vertical direction. The pattern of wind pressure coefficients, however, is not properly described in the existing wind-load codes.

Effect of Initial Indentation Position on Plastic Deformation Behaviors of Polycrystalline Materials via Molecular Dynamics Simulation

Pengyue Zhao,Yongbo Guo 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2019 NANO Vol.14 No.1

Polycrystalline materials can be divided into four types of microstructural components, including grain cell (GC), grain boundary (GB), triple junction (TJ) and vertex points (VP). Nanoindentation at different microstructural components on the polycrystalline materials surface can lead to different plastic deformation behaviors of the polycrystalline materials. Due to experimental limitations, the indentation-induced internal stress and defect evolution process are difficult to investigate directly, especially for the polycrystalline materials with grain size less than 100 nm. The molecular dynamics (MD) simulations were performed to unravel the initial indentation position effect on the elasticity/plastic deformation mechanism of polycrystalline copper. The results reveal that the initial indentation position governs the indentation force variation and defect distribution range due to the different dimensionalities of the microstructural components. The defect propagation as well as the internal stress transmission in the GC regions tend to transfer to the low-dimensional microstructural components of the interfaces. In addition, the atomic internal stress and potential energy accumulation/release of the microstructural component atoms during the nanoindentation process are also investigated, revealing that the atomic internal stress and potential energy in the VPs vary earliest, followed by the TJs, GBs and GCs.

miR-34a Inhibitor May Effectively Protect against Sevoflurane-Induced Hippocampal Apoptosis through the Wnt/β-Catenin Pathway by Targeting Wnt1

Xiaoling Zhao,Yue Sun,Yongbo Ding,Jun Zhang,Kezhong Li 연세대학교의과대학 2018 Yonsei medical journal Vol.59 No.10

Purpose: Research has shown that sevoflurane-induced toxicity causes neurodegeneration in the developing brain. miR-34a has been found to negatively regulate ketamine-induced hippocampal apoptosis and memory impairment. However, the role of miR-34a in sevoflurane-induced hippocampal neurodegeneration remains largely unclear. Materials and Methods: C57/BL6 mice (7-day-old) inhaled 2.3% sevoflurane for 2 h/day over 3 consecutive days. miR-34a expressionwas reduced through intracerebroventricular injection with miR-34a interference lentivirus vector (LV-anti-miR-34a) into mouse hippocampus after anesthesia on the first day of exposure. Hippocampal apoptosis was detected by TUNEL assay and flow cytometry analysis. Spatial memory ability was evaluated by the Morris water maze test. The interaction between miR-34a and Wnt1 was confirmed by luciferase reporter assay, RNA immunoprecipitation, Western blot, and immunofluorescence staining. The effects of miR-34a on protein levels of B-cell lymphoma 2 (Bcl-2), bcl-2-like protein 4 (Bax), and Wnt/β-catenin pathway-related proteins were evaluated using Western blot analysis. Results: Sevoflurane upregulated hippocampal miR-34a, and miR-34a inhibitor attenuated sevoflurane-induced hippocampal apoptosis and memory impairment. miR-34a negatively regulated Wnt1 expression by targeting miR-34a in hippocampal neurons. Moreover, forced expression of Wnt1 markedly undermined miR-34a-mediated enhancement of sevoflurane-induced apoptosis of hippocampal neurons, while Wnt1 silencing greatly restored anti-miR-34a-mediated repression of sevoflurane-inducedapoptosis of hippocampal neurons. Increased expression of miR-34a inhibited the Wnt/β-catenin pathway in hippocampalneurons exposed to sevoflurane, while anti-miR-34a exerted the opposite effects. Conclusion: miR-34a inhibitor may effectively protect against sevoflurane-induced hippocampal apoptosis via activation of the Wnt/β-catenin pathway by targeting Wnt1.

Full Scale Experiment for Vibration Analysis of Ice-Coated Bundled-Conductor Transmission Lines

Guifeng Zhao,Zhongbin Lu,Xu Wang,Yongbo Peng,Shaojun Chang 대한토목학회 2022 KSCE Journal of Civil Engineering Vol.26 No.1

Full scale experiment has received increasing attention in recent years for the reliability analysis of power supplies and power systems. In this paper, the vibration behaviours of conductors with and without D-section ice coatings are addressed by virtue of a field test platform consisting of the prototype of a transmission tower-line system. Utilizing fibre Bragg grating sensors, the vibration of conductors under artificial displacement and natural wind excitations are monitored, and their dynamic characteristics are assessed by the spectral analysis and the identification technique of Hilbert-Huang transform. It is revealed that the vibrations of ice-free and ice-coated multi-bundled conductors vary wildly despite under similar artificial displacements and natural wind excitations. The vibration of ice-coated conductors is mainly dominated by their low-order modes, especially in the frequency range of 0.24 − 2.0 Hz; while the vibration of ice-free conductors gains more benefits from their high-order modes. Compared to the ice-free conductors, the conductors with eccentric ice coating are prone to suffer from galloping under specified wind attack angle; although their vibrations are still controlled by the low-order modes, yet the frequency values of the dominant modes have changed from one wind attack angle case to another. This kind of frequency modulation phenomenon indicates that nonlinear vibration characteristics of ice-coated conductors might change under different wind conditions, which brings great challenges to the research of wind-induced vibration characteristics of ice-coated conductors.

Dynamics of Endogenous Cytokinins during Phase Change in Malus domestica Borkh

Xinzhong Zhang,Yongbo Zhao,Guangpeng Wang,Ruifeng Chang,Chun-min Li,Huairui Shu 한국원예학회 2006 한국원예학회 기타간행물 Vol.- No.-

Dynamics of Endogenous Polyamines in Seedling Trees of Pyrus ussuriensis Maxim. × P. bretschneideri Rehd

Chunmin Li,Xinzhong Zhang,Wenquan Yue,Yongbo Zhao,Wenfang Zu,Guangpeng Wang,Ruifeng Chang,Huairui Shu 한국원예학회 2006 한국원예학회 기타간행물 Vol.- No.-

Evaluating genetic diversity and identifying priority conservation for seven Tibetan pig populations in China based on the mtDNA D-loop

Ge Qianyun,Gao Caixia,Cai Yuan,Jiao Ting,Quan Jinqiang,Guo Yongbo,Zheng Wangshan,Zhao Shengguo 아세아·태평양축산학회 2020 Animal Bioscience Vol.33 No.12

Objective: Tibetan pigs, an excellent species unique to China, face serious threats, which in turn affects the development and utilization of the outstanding advantages of plateau hypoxia adaptability and reduces their genetic diversity. Therefore, a discussion of measures to conserve this genetic resource is necessary. The method, based on genetic diversity, genetic divergence and total genetic contribution rate of population, reflects the priority conservation order and varies depending on the three different purposes of conservation. Methods: We analyzed mitochondrial DNA control region (D-loop) variation in 1,201 individuals from nine Tibetan pig populations across five provinces and downloaded 564 mtDNA D-loop sequences from three indigenous pig breeds in Qinghai, Sichuan, and Yunnan Provinces distributed near the Tibetan pigs. Results: We analyzed three different aspects: Changdu Tibetan pigs have the highest genetic diversity, and from the perspective of genetic diversity, the priority conservation is Changdu Tibetan pigs. Hezuo Tibetan pigs have the highest genetic contribution, so the priority conservation is Hezuo Tibetan pigs in the genetic contribution aspect. Rkaze Tibetan pigs were severely affected by indigenous pig breeds, so if considering from the perspective of introgression, the priority conservation is Rkaze Tibetan pigs. Conclusion: This study evaluated genetic diversity and comprehensively assessed conservation priority from three different aspects in nine Tibetan pig populations.

The domestication event of the Tibetan pig revealed to be in the upstream region of the Yellow River based on the mtDNA D-loop

Ge, Qianyun,Gao, Caixia,Cai, Yuan,Jiao, Ting,Quan, Jinqiang,Guo, Yongbo,Zheng, Wangshan,Zhao, Shengguo Asian Australasian Association of Animal Productio 2020 Animal Bioscience Vol.33 No.4

Objective: Evidence from previous reports indicates that pig domestication in East Asia mainly occurred in the Mekong region and the middle and downstream regions of the Yangtze River. Further research identified two new origin centers for domestic pigs in the Tibetan Plateau and the islands of Southeast Asia. However, due to the small sample size of Tibetan pigs, details of the origin and spread of Tibetan pigs has not yet been established. Methods: We analyzed mitochondrial DNA control region (D-loop) variation in 1,201 individuals from nine Tibetan pig populations across five provinces. Comprehensive Tibetan pig samples were taken to perform the most detailed analysis of Tibetan pigs to date. Results: The result indicate that Rkaze pigs had the lowest level of diversity, while Changdu pigs had the highest diversity. Interestingly, these two populations were both in the Tibetan Plateau area. If we calculate diversity in terms of each province, the Tibetan Plateau area had the lowest diversity, while the Chinese province of Gansu had the highest diversity. Diversity gradient analysis of major haplotypes suggested three domestication centers of Tibetan pigs in the Tibetan Plateau and the Chinese provinces of Gansu and Yunnan. Conclusion: We found two new domestication centers for Tibetan pigs. One is in the Chinese province of Gansu, which lies in the upstream region of the Yellow River, and the other is in the Chinese province of Yunnan.