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Novel scaling law for estimating propeller tip vortex cavitation noise from model experiment
Park, Jisoo,Seong, Woojae Springer-Verlag 2017 Journal of hydrodynamics. Ser. B Vol.29 No.6
<P>The tip vortex cavitation (TVC) noise of marine propellers is of interest due to the environmental impacts from commercial ships as well as for the survivability of naval ships. Due to complicated flow and noise field around a marine propeller, a theoretical approach to the estimation of TVC noise is practically unrealizable. Thus, estimation of prototype TVC noise level is realized through extrapolation of the model TVC noise level measured in a cavitation tunnel. In this study, for the prediction of prototype TVC noise level from a model test, a novel scaling law reflecting the physical basis of TVC is derived from the Rayleigh-Plesset equation, the Rankine vortex model, the lifting surface theory, and other physical assumptions. Model and prototype noise data were provided by Samsung Heavy Industries (SHI) for verification. In applying the novel scaling law, similitude of the spectra of nuclei is applied to assume the same nuclei distribution in the tip vortex line of the model and the prototype. It was found that the prototype TVC noise level predicted by the novel scaling law has better agreement with the prototype TVC noise measurement than the prototype TVC noise level predicted by the modified ITTC noise estimation rule.</P>
Jisoo Park,Eun Young Eo,Kyoung-Hee Lee,Jong Sun Park,Jae-Ho Lee,Chul-Gyu Yoo,Choon-Taek Lee,조영재 대한중환자의학회 2015 Acute and Critical Care Vol.30 No.3
Background: Arginine vasopressin (AVP) is widely used as a vasopressor agent. Some recent studies have suggested that AVP may exert an immunomodulatory effect. However, the mechanism about the anti-inflammatory effect of AVP is not well known. We investigated the effect of AVP on the ihibitor of kappa B (IκBα)/nuclear factor-kappa B (NF-κB) pathway in RAW 264.7 cells. Methods: Cultured RAW 264.7 cells were pretreated with AVP and stimulated with lipopolysaccharide (LPS). To evaluate the effect of AVP on inflammatory cytokines, the concentration of interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) were assessed by an enzyme-linked immunosorbent assay technique. The expression of IκBα and nuclear translocation of NF-κB p65 were measured by Western blotting, and IκB kinase (IKK) activity was analyzed by an in vitro immune complex kinase assay. To confirm the AVP effect on IκBα/NF-κB cascade and via V2 receptor, we added tolvaptan (V2 receptor antagonist) after AVP pretreatment. Results: The increase of IL-6 and TNF-α in LPS-stimulated RAW 264.7 cells was suppressed by a treatment with AVP. Pretreatment of AVP inhibited increasing of IKK activity and IκBα degradation induced by LPS in RAW 264.7 cells. Furthermore, LPS induced and NF-κB transcription was inhibited by AVP pretreatment. The observed changes in IKK activity, IκBα degradation and NF-κB transcription by AVP was abolished by tolvaptan treatment. Conclusions: Our results suggest that AVP showed anti-inflammatory effect on LPS-induced IκBα/NF-κB cascade in mouse macrophages via V2 receptors.