TR-PIV measurement of separated and reattaching turbulent flow over a surface-mounted square cylinder

Liu Liu SHI,Ying Zheng LIU,Jin Jin WAN 대한기계학회 2010 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.24 No.1

The separated and reattaching turbulent flow over a surface-mounted two-dimensional square cylinder was experimentally studied by using time-resolved particle image velocimetry (TR-PIV). A total of 61,440 instantaneous image frames were acquired at a framing rate of 125 Hz, yielding a reliable result of the statistical quantities. The time-averaged features of the separated and reattaching flow were analyzed in terms of distributions of the velocity vectors, vorticity, the streamwise velocity fluctuation intensity and shear stress. The association between the large-scale vortical structures and spatial variation of these time-averaged quantities were thoroughly discussed. The unsteady features of the flow were revealed from distributions of the reverse-flow intermittency, space-time contour plot of the fluctuating streamwise velocity, and cross-correlation of the streamwise velocity. Subsequently, a comprehensive understanding of the contribution of the flow structures into the fluctuating flow field was gained by using a snapshot proper orthogonal decomposition (POD)analysis. The results showed that the linear combination of the first five POD modes, which capture 57% of the fluctuation energy, was capable of representing the large-scale behaviors of the separated and reattaching turbulent flow in the senses of spectrum, instantaneous feature and spatial variation of the velocity fluctuation intensity.

Massive open online course's teaching reform path of integrating ideological and political elements into the general education course of corporate crime investigation

Liu Aijiao(Aijiao Liu),Shi Jiangshan(Jiangshan Shi),Yang Renqiao(Renqiao Yang) 아시아사회과학학회 2023 Jornal of Asia Social Science Vol.10 No.2

The investigation of corporate crimes is a key course in public security colleges, which has high application, sociality, practicality and theory. With the rapid development of modern information technology, “Internet + education” has become the main direction of undergraduate teaching reform. It is extremely important to combine massive open online course with the teaching of corporate crime investigation. On the premise of expanding college students' professional knowledge and subject knowledge, general education can shape students' thinking paradigm in line with socialist core values and ensure students to develop scientific three views. Taking the general course “Investigation of Corporate Crime Cases” in public security colleges as an example, this paper discusses the necessity, problems and relevant countermeasures of integrating ideological and political elements into the online teaching of general education courses, and provides reference for the design and practice of ideological and political courses in the online teaching of general education courses.

Surface-Displayed Porcine IFN-λ3 in Lactobacillus plantarum Inhibits Porcine Enteric Coronavirus Infection of Porcine Intestinal Epithelial Cells

Yong-Shi Liu,Qiong Liu,Yanlong Jiang,Wentao Yang,Hai-Bin Huang,Chun-Wei Shi,Gui-Lian Yang,Chun-Feng Wang 한국미생물·생명공학회 2020 Journal of microbiology and biotechnology Vol.30 No.4

Interferon (IFN)-λ plays an essential role in mucosal cells which exhibit strong antiviral activity. Lactobacillus plantarum (L. plantarum) has substantial application potential in the food and medical industries because of its probiotic properties. Alphacoronaviruses, especially porcine epidemic diarrhea virus (PEDV) and transmissible gastroenteritis virus (TGEV), cause high morbidity and mortality in piglets resulting in economic loss. Co-infection by these two viruses is becoming increasingly frequent. Therefore, it is particularly important to develop a new drug to prevent diarrhea infected with mixed viruses in piglets. In this study, we first constructed an anchored expression vector with CWA (C-terminal cell wall anchor) on L. plantarum. Second, we constructed two recombinant L. plantarum strains that anchored IFN-λ3 via pgsA (N-terminal transmembrane anchor) and CWA. Third, we demonstrated that both recombinant strains possess strong antiviral effects against coronavirus infection in the intestinal porcine epithelial cell line J2 (IPEC-J2). However, recombinant L. plantarum with the CWA anchor exhibited a more powerful antiviral effect than recombinant L. plantarum with pgsA. Consistent with this finding, Lb.plantarum-pSIP-409-IFN- λ3-CWA enhanced the expression levels of IFN-stimulated genes (ISGs) (ISG15, OASL, and Mx1) in IPEC-J2 cells more than did recombinant Lb.plantarum-pSIP-409-pgsA'-IFN-λ3. Our study verifies that recombinant L. plantarum inhibits PEDV and TGEV infection in IPEC-J2 cells, which may offer great potential for use as a novel oral antiviral agent in therapeutic applications for combating porcine epidemic diarrhea and transmissible gastroenteritis. This study is the first to show that recombinant L. plantarum suppresses PEDV and TGEV infection of IPEC-J2 cells.

Experimental study of cactus-like body shape on flow-induced vibration mitigation of clustered cylinders

Shi Chen,Liu Yang,Wang Jialu,Chen Fabo,Liu Zhihui,Bao Xingxian 대한조선학회 2021 International Journal of Naval Architecture and Oc Vol.13 No.1

Vortex-Induced Vibration (VIV) is a major contributor to the fatigue damage of marine risers which are often arranged in an array configuration. In addition to helical strakes and fairings, studies have been strived in searching for possible VIV suppression techniques. Inspired by giant Saguaro Cacti, flexible cylinders of different cactus-shaped cross sections were tested in a water tunnel facility, and test results showed that cactus-like body shapes reduced VIV responses of a cylinder at no cost of significant increase of drag. A series of experiments were conducted on a pair of two tandem-arranged flexible cylinders and an array of four cylinders in a square configuration to investigate the effects of wake on the dynamic responses of cylinders and the VIV mitigation effectiveness of the cactus-like body shape. Results showed that the cylinders in a square configuration, either at the upstream or downstream positions, might have larger dynamic responses than those of a single cylinder. The cactus-like body shape could mitigate VIV responses of cylinders at upstream positions in an array configuration; however, similar to helical strakes, the mitigation efficiency was reduced on downstream cylinders. Note that the cactus-like cross-sectional shape investigated was not optimized for VIV suppression. The present study indicates that the modification of the cross-sectional shape of a cylinder to a well-designed cactus-like shape may be used as an alternative technique to mitigate the VIV of marine risers.

Overlapping Stents-Assisted Coiling for Vertebral Artery Dissecting Aneurysm : LVIS Stent within Neuroform EZ Stent

Liu, Xing-Long,Wang, Bin,Zhao, Lin-Bo,Jia, Zhen-Yu,Shi, Hai-Bin,Liu, Sheng The Korean Neurosurgical Society 2022 Journal of Korean neurosurgical society Vol.65 No.4

Objective : To evaluate the safety and efficacy of an overlapped stenting-assisted coiling technique in treating vertebral artery dissecting aneurysm (VADA) via Low-profile Visualized Intraluminal Support (LVIS) stent-within-Neuroform EZ stent. Methods : From January 2017 to June 2019, 18 consecutive patients with VADAs (ruptured : unruptured=5 : 13) were treated with the overlapping stents assisted-coiling technique in our center. The overlapping manner was a Neuroform EZ stent being deployed first, followed by LVIS stents placement using the 'shelf' technique. The patients' clinical characteristics, technical feasibility and safety, and immediate and follow-up angiographic results were retrospectively reviewed. Results : Seventeen (94.4%) procedures were technically successful with an exact deployment of the stents and patent parent or perforator arteries. The immediate angiographies after procedure confirmed Raymond class I, II, and III occlusion of VADAs were in 12 (66.7%), two (11.1%), and four cases (22.2%), respectively. Post-procedural complications developed in one patient (5.6%) with minor brainstem infarctions, which resulted from an in-stent thrombosis during the procedure. Angiographic follow-up at 5.7 months (range 3 to 9 months) demonstrated Raymond class I and II occlusion were in all cases (100%). The modified Rankin Scale scores at 21.3 months (range 15 to 42 months) 0-2 in 17 cases (94.4%) and three in one case (5.6%). Conclusion : Overlapping stents via LVIS stent-within-Neuroform EZ stent combined with coiling is safe and effective for patients with VADA in the midterm results.

Global Disease Burden and Attributable Risk Factor Analysis of Asthma in 204 Countries and Territories From 1990 to 2019

Liu Hailing,Zhang Jing,Liu Li,Lian Guoli,Shi Ruiming,Xu Man,Yang Juan,Liu Xiaohong 대한천식알레르기학회 2023 Allergy, Asthma & Immunology Research Vol.15 No.4

Purpose: Asthma is a common chronic inflammatory respiratory tract disease with high morbidity and mortality. The global trends in asthma burden remain poorly understood, and asthma incidence has increased during the worldwide coronavirus disease 2019 (COVID-19) pandemic. This study aimed to provide a comprehensive view of the global distribution of asthma burden and its attributable risk factors from 1990 to 2019. Methods: Based on the Global Burden of Disease Study 2019 Database, asthma incidence, deaths, disability-adjusted life years (DALYs), the corresponding age-standardized incidence rate (ASIR), age-standardized death rate (ASDR), age-standardized DALY rate, and estimated annual percentage change were analyzed according to age, sex, sociodemographic index (SDI) quintiles, and locations. Risk factors contributing to asthma deaths and DALYs were also investigated. Results: Globally, the asthma incidence increased by 15%, but deaths and DALYs decreased. The corresponding ASIR, ASDR, and age-standardized DALY rate also decreased. The high SDI region had the highest ASIR, and the low SDI region had the highest ASDR. The ASDR and age-standardized DALY rate were negatively correlated with the SDI. The low-middle SDI region, particularly South Asia, showed the highest asthma-related deaths and DALYs. The incidence peak was under 9 years old, and more than 70% of all deaths occurred in the population over 60 years old. Smoking, occupational asthmagens, and a high body mass index were the main risk factors for asthma-related mortality and DALYs, and their distributions varied between sexes. Conclusions: Globally, the asthma incidence has increased since 1990. The greatest asthma burden is borne by the low-middle SDI region. The 2 groups that need special attention are those under 9 years old and those over 60 years old. Targeted strategies are needed to reduce the asthma burden based on geographic and sex-age characteristics. Our findings also provide a platform for further investigation into the asthma burden in the era of COVID-19.

An Interactive Planning and Scheduling Framework for Optimising Pits-to-Crushers Operations

Liu, Shi Qiang,Kozan, Erhan Korean Institute of Industrial Engineers 2012 Industrial Engineeering & Management Systems Vol.11 No.1

In this paper, an interactive planning and scheduling framework are proposed for optimising operations from pits to crushers in ore mining industry. Series of theoretical and practical operations research techniques are investigated to improve the overall efficiency of mining systems due to the facts that mining managers need to tackle optimisation problems within different horizons and with different levels of detail. Under this framework, mine design planning, mine production sequencing and mine transportation scheduling models are integrated and interacted within a whole optimisation system. The proposed integrated framework could be used by mining industry for reducing equipment costs, improving the production efficiency and maximising the net present value.

Multiple Unbounded Positive Solutions for the Boundary Value Problems of the Singular Fractional Differential Equations

Liu, Yuji,Shi, Haiping,Liu, Xingyuan Department of Mathematics 2013 Kyungpook mathematical journal Vol.53 No.2

In this article, we establish the existence of at least three unbounded positive solutions to a boundary-value problem of the nonlinear singular fractional differential equation. Our analysis relies on the well known fixed point theorems in the cones.

Study on the Industrial Process of Rubber Anti-oxidant RD

Liu, Yu,Gao, Qinyu,Liu, Lianxin,Shi, Guangxia Korean Chemical Society 2011 대한화학회지 Vol.55 No.5

This paper is on the industrial synthesis process of anti-oxidant RD ((2,2,4-trimethyl-1,2-dihydroquinoline polymer $(C_{12}H_{15}N)_n$. n=2-4)).The content of dimer, trimer and tetramer of RD as the inspection targets, using the orthogonal design method - take the ratios of keto-amine, the reaction time, the reaction temperatures and the ratios of catalyst acid-amine as inspect factors - to optimized the reaction condition. The results indicate that the best ratio of keto-amine is 2:1, the time of salification and condensation is 3 hours and 7.5 hours. The range of temperature of salification and condensation is $135^{\circ}C$ and $120-125^{\circ}C$, and that the best ratio of acid-amine is 0.2: 1 (the proportion is the concentration ratio for mole). Under the optimization conditions, the yield of RD was stabilized and content of RD more than 45%.

Cloning and expression of a wild eggplant cytochrome P450 gene, StoCYP77A2, involved in plant resistance to Verticillium dahliae

Liu Yang,Ce Shi,Xiaoying Mu,Chao Liu,Ke Shi,Wen-jiao Zhu,Qing Yang 한국식물생명공학회 2015 Plant biotechnology reports Vol.9 No.4

Plant P450s play an important role in plant response to environmental stimuli, especially to pathogen challenge, besides leading to the biosynthesis of secondary metabolites. In this work, a Verticillium dahliae-induced cDNA sequence was cloned from wild eggplant Solanum torvum and designated StoCYP77A2. StoCYP77A2 encodes a 511-amino acid peptide that shows sequence homology to the plant CYP77 family. StoCYP77A2 is expressed in a tissue-specific manner with the highest expression level in stem. The expression level of StoCYP77A2 was increased in wild eggplants which were infected with Verticillium dahlia. We expressed StoCYP77A2 in V. dahliae-sensitive tobacco, and the transgenic tobacco plants were more resistant to V. dahliae infection than the wild type. Protein extraction of transgenic tobacco showed strong antifungal activity against V. dahliae, indicating that StoCYP77A2 may be involved in the synthesis of some antimicrobial compounds. These results suggest that StoCYP77A2 plays a role in plant defense to V. dahliae infection.