http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
- 中文 을 입력하시려면 zhongwen을 입력하시고 space를누르시면됩니다.
- 北京 을 입력하시려면 beijing을 입력하시고 space를 누르시면 됩니다.
RISS 인기검색어
- 검색키워드
- 저자 : S. Martínez-Aranda (검색결과 2 건)
- 무료
- 기관 내 무료
- 유료
-
Dynamic Response of Low-Aspect-Ratio Cantilever NACA0012 Airfoil at Low-To-Moderate Reynolds Numbers
S. Martínez-Aranda,A. García-González,L. Parras,J. F. Velazquez-Navarro,C. del Pino 한국항공우주학회 2018 International Journal of Aeronautical and Space Sc Vol.19 No.3
The influence of the angle of attack (AoA) and the chord based Reynolds number (Rec) on the lift and drag coefficients has been analyzed experimentally in a low-aspect-ratio NACA0012 airfoil, AR = 2. Results are shown for chord based Reynolds numbers in the range 3.33 × 104 ≤ Rec ≤ 1.33 × 105 and AoA between 0º and +35º, the stall angle being close to 12º. The aerodynamic characteristics show an increase and decrease of lift and drag force fluctuations for AoA greater than the stall angle. The explanation of how these aerodynamic variations appear has been reported numerically and it is based on two-dimensional effects which are mainly the unstable laminar separation bubble (LSB) and the subsequent downstream propagation of leading edge vortex (LEV) as AoA increases. In addition, the dynamic response of the wing has been studied using frequency analysis. We compute the power spectral density (PSD) from the temporal evolution of the net force exerted over the wing, showing that the main response of the wing is the presence of two natural frequencies of the wing-base system. The mean PSD suddenly increases for Rec ≈ 1 × 105, particularly at AoA exceeding the critical point that corresponds to the stall angle. Finally, and despite from the fact that our model is rigid, we find PSD peaks at very low and high frequencies in agreement with other authors’ results which correspond to energetic modes in the wingtip vortex and the formation and emission of coherent turbulent structures behind the airfoil, respectively.
-
Nydia Ávila-Vanzzini,Juan Francisco Fritche-Salazar,Nelva Marina Vázquez-Castro,Pedro Rivera-Lara,Oscar Pérez-Méndez,Humberto Martínez-Herrera,Mario Gómez-Sánchez,Alberto Aranda-Frausto,Héctor Herrera 한국심초음파학회 2016 Journal of Cardiovascular Imaging (J Cardiovasc Im Vol.24 No.4
Background: Severe aortic stenosis (AS), leads to pathological left ventricular remodeling that may worsen with concomitantoverweight and obesity (OW/O). Methods: We aimed to prospectively analyze the impact of OW/O on ventricular remodeling in severe AS, by evaluating thepercentage of intraendomyocardial fibrosis (PIEF) and the percentage of infiltrating intraendocardial lipid vacuoles (PIELV) andits relationship to global longitudinal strain (GLS) in patients with OW/O. Results: 44 patients with severe AS were included, 13 non-obese (29%) and 31 OW/O (71%), all of them with left ventricularejection fraction ≥ 55%. GLS was evaluated with 2D speckle tracking. During valve replacement, an endocardial biopsy wasobtained, where PIEF and PIELV were analyzed. Patients with higher PIEF and PIELV had greater body mass index (p < 0.0001)and worse GLS (p < 0.0053). A GLS cut-off point < -14% had a sensitivity of 75%, and a specificity of 92.8% to detect importantPIEF (AUC: 0.928, 95% confidence interval: 0.798–1.00). On multivariate analysis, OW/O and PIELV were independentlyassociated to the PIEF, and OW/O and PIEF were independently associated to GLS. A high correlation between the amount ofPIELV and PIEF were found. Conclusion: Patients with severe AS and OW/O have greater PIEF and PIELV, suggesting more pathological remodeling. GLS is useful to detect subclinical myocardial injury and is potentially useful for endomyocardial fibrosis detection. The presenceof higher PIELF may be a trigger factor for the development of intraendomyocardial fibrosis.
연관 검색어 추천
이 검색어로 많이 본 자료
활용도 높은 자료
