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Evaluation of subgrid scale models in turbulent large eddy simulations of pumpjet propulsor
Ke Lin,Ye Jinming,He Wei 대한조선학회 2024 International Journal of Naval Architecture and Oc Vol.16 No.-
To assess the effectiveness of subgrid scale (SGS) models on the prediction results of unsteady loads and turbulent fluctuation of pumpjet propulsors equipped with both front and rear stators, a pumpjet propulsor computational model with attached parts at the model scale is developed using a fully structured mesh, and large eddy simulations are conducted. The computational results of the different SGS models are compared based on five aspects: open water characteristics, turbulence parameters, incoming turbulence spectrum, vortex structure, and fluctuating pressure. Their results are also compared with the experimental values, and the correlation between the internal flow characteristics of the pumpjet propulsor and the turbulent fluctuation is analyzed. According to the results, as regards the prediction of the open water performance of the pumpjet propulsor containing both front and rear stators, the overall trend obtained by the three subgrid models is similar, and the error between the values predicted by the SL model and the experimental ones is the smallest. At the same mesh level, the turbulent fluctuating scale obtained by the SL model is larger than that obtained by the WALE and DSL models, and the turbulent time scale obtained by the DSL model has the smallest fluctuation in the circumferential direction. Among the three SGS models, the turbulent fluctuating scale of the SL model is larger than those of the WALE and DSL models. The SL model exhibits the largest energy dissipation among the three SGS models, followed by the DSL model, while that of the WALE model is the smallest. In the WALE model, the leakage vortex at the top of the blade is the longest, followed by the DSL model, while it is the shortest in the SL model. In the WALE and DSL models, the fluctuating load fluctuates more in the transition region from the middle section to the trailing edge of the blade.
Bile Acid Transporters Are Expressed and Heterogeneously Distributed in Rat Bile Ducts
Zhu-lin Luo,Long Cheng,Tao Wang,Li-jun Tang,Fu-zhou Tian,Ke Xiang,Lin Cui 거트앤리버 소화기연관학회협의회 2019 Gut and Liver Vol.13 No.5
Background/Aims: Cholangiocytes are capable of reabsorbing bile salts from bile, but the pathophysiological significance of this process is unclear. To this end, we detected the expression and distribution of bile acid transport proteins in cholangiocytes from normal rat liver and analyzed the possible pathophysiological significance. Methods: Bile duct tissues of Sprague-Dawley rats were isolated by enzymatic digestion and mechanical isolation, and then divided into large and small bile duct tissues. Immunohistochemistry, real-time polymerase chain reaction and Western blotting were used to determine the expression of the apical sodium-dependent bile acid transporter (ASBT), ileal bile acid binding protein (IBABP), and basolateral organic solute transporter α (Ostα) in the biliary tract system of rats. Differences in the expression and distribution of these proteins were analyzed. Results: In cholangiocytes, ASBT and IBABP were mainly expressed in cholangiocytes of the large bile ducts, in which the expression of both was significantly higher than that in the small ducts (p<0.05). Ostα was simultaneously expressed in cholangiocytes of both the large and small bile ducts, showing no significant difference in expression between the two groups of bile ducts (p>0.05). Conclusions: Bile acid transporters are expressed and heterogeneously distributed in rat bile ducts, indicating that bile acid reabsorption by cholangiocytes might mainly occur in the large bile ducts. These findings may help explore the physiology of bile ducts and the pathogenesis of various cholangiopathies.
A re-examination of the current design rule for staggered bolted connections
Xue-Mei Lin,Michael C. H. Yam,Ke Ke,Binhui Jiang,Qun He 국제구조공학회 2023 Steel and Composite Structures, An International J Vol.46 No.3
This paper summarised and re-examined the theoretical basis of the commonly used design rule developed by Cochrane in the 1920s to consider staggered bolt holes in tension members, i.e., the s 2 /4g rule. The rule was derived assuming that the term two times the bolt hole diameter (2d0) in Cochrane’s original equation could be neglected, and assuming a value of 0.5 for the fractional deduction of a staggered hole in assessing the net section area. Although the s 2 /4g rule generally provides good predictions of the staggered net section area, the above-mentioned assumptions used in developing the rule are doubtful, in particular for a connection with a small gauge-to-bolt-hole diameter (g/d0) ratio. It was found that the omission of 2d0 in Cochrane’s original equation appreciably overestimates the net section area of a staggered bolted connection with a small g/d0 ratio. However, the assumed value of 0.5 for the fractional deduction of a staggered hole underestimates the staggered net section area for small g/d0 ratios. To improve the applicability of the above two assumptions, a modified design equation, which covers a full range of g/d0 ratio, was proposed to accurately predict the staggered net section area and was validated by the existing test data from the literature and numerical data derived from this study. Finally, a reliability analysis of the test and numerical data was conducted, and the results showed that the reliability of the modified design equation for evaluating the net section resistance of staggered bolted connections can be achieved with the partial factor of 1.25.
Implementation of point-of-care platforms for rapid detection of porcine circovirus type 2
Chiao-Hsu Ke,Mao-Yuan Du,Wang-Ju Hsieh,Chiu-Chiao Lin,James Mingjuh Ting,Ming-Tang Chiou,Chao-Nan Lin The Korean Society of Veterinary Science 2024 Journal of Veterinary Science Vol.25 No.2
Background: Porcine circovirus type 2 (PCV2) infection is ubiquitous around the world. Diagnosis of the porcine circovirus-associated disease requires clinic-pathological elements together with the quantification of viral loads. Furthermore, given pig farms in regions lacking access to sufficient laboratory equipment, developing diagnostic devices with high accuracy, accessibility, and affordability is a necessity. Objectives: This study aims to investigate two newly developed diagnostic tools that may satisfy these criteria. Methods: We collected 250 specimens, including 170 PCV2-positive and 80 PCV2-negative samples. The standard diagnosis and cycle threshold (Ct) values were determined by quantitative polymerase chain reaction (qPCR). Then, two point-of-care (POC) diagnostic platforms, convective polymerase chain reaction (cPCR, qualitative assay: positive or negative results are shown) and EZtargex (quantitative assay: Ct values are shown), were examined and analyzed. Results: The sensitivity and specificity of cPCR were 88.23% and 100%, respectively; the sensitivity and specificity of EZtargex were 87.65% and 100%, respectively. These assays also showed excellent concordance compared with the qPCR assay (κ = 0.828 for cPCR and κ = 0.820 for EZtargex). The statistical analysis showed a great diagnostic power of the EZtargex assay to discriminate between samples with different levels of positivity. Conclusions: The two point-of-care diagnostic platforms are accurate, rapid, convenient and require little training for PCV2 diagnosis. These POC platforms can discriminate viral loads to predict the clinical status of the animals. The current study provided evidence that these diagnostics were applicable with high sensitivity and specificity in the diagnosis of PCV2 infection in the field.
Ke-Ming Wang,Feng Chen,Hui Hu,Hui-Hao Xia,Xue-Lin Wang,Bo-Rong Shi,Qing-Ming Lu 한국진공학회(ASCT) 2003 Applied Science and Convergence Technology Vol.12 No.S1
Both LiNbO₃ and KTiOPO₄ samples were implanted with 350 keV H^+ and He^+ ions at different doses ranging from 1×10^(16) to of 5×10^(16) ions/㎠. Single and multi-energy implantations were performed at room temperature. Mono-mode or a few modes in both LiNbO₃ and KTiOPO₄ waveguides were observed. The effect of temperature on the refractive index profiles of LiNbO₃ and KTiOPO₄ waveguids was studied. The temperature covered from room temperature, 200℃, 194.5 K (dry ice) and 77K (liquid nitrogen). Different mechanisms are needed to interpret the observed behavior. A n_e increased mono-mode LiNbO₃ waveguide was formed by multi-energy keV He^+ ions.