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Numerical modeling of a spherical buoy moored by a cable in three dimensions
Zhu, X.,Yoo, W. S. CHINA MACHINE PRESS/ SPRINGER VERLAG 2016 Chinese journal of mechanical engineering Vol.29 No.3
<P>Floating facilities have been studied based on the static analysis of mooring cables over the past decades. To analyze the floating system of a spherical buoy moored by a cable with a higher accuracy than before, the dynamics of the cables are considered in the construction of the numerical modeling. The cable modeling is established based on a new element frame through which the hydrodynamic loads are expressed efficiently. The accuracy of the cable modeling is verified with an experiment that is conducted by a catenary chain moving in a water tank. In addition, the modeling of a spherical buoy is established with respect to a spherical coordinate in three dimensions, which can suffers the gravity, the variable buoyancy and Froude-Krylov loads. Finally, the numerical modeling for the system of a spherical buoy moored by a cable is established, and a virtual simulation is proceeded with the X- and Y-directional linear waves and the X-directional current. The comparison with the commercial simulation code ProteusDS indicates that the system is accurately analyzed by the numerical modeling. The tensions within the cable, the motions of the system, and the relationship between the motions and waves are illustrated according to the defined sea state. The dynamics of the cables should be considered in analyzing the floating system of a spherical buoy moored by a cable.</P>
J. He,Q.Z. Cai,D. Zhu,Q. Luo,D.Q. Zhang,X.W. Li,X. Zhao,W. Sun 한국물리학회 2011 Current Applied Physics Vol.11 No.1
A WO_3/TiO_2 composite film was in-situ prepared in tungstate electrolyte and characterized by Electron microscopy, X-ray diffraction, UV―Vis spectrophotometer and Photoluminescence. The oxide film consists of mixture phases of anatase and rutile, showing porous structures and metallurgical bond with substrate. With the incorporation of WO_3 into TiO_2, the optical absorption edge of TiO_2 filmwas shifted to longer wavelength slightly and the separation between electrons and holes was promoted effectively. WO_3/TiO_2 composite film with increased photo quantum efficiency will be promising in the treatment of environmental pollutants.
Udalski, A.,Yee, J. C.,Gould, A.,Carey, S.,Zhu, W.,Skowron, J.,Kozłowski, S.,Poleski, R.,Pietrukowicz, P.,Pietrzyx144,ski, G.,Szymax144,ski, M. K.,Mró,z, P.,Soszyx144,ski, I.,Ulaczyk, K.,W IOP Publishing 2015 The Astrophysical journal Vol.799 No.2
<P>We combine Spitzer and ground-based observations to measure the microlens parallax vector pi(E), and thus the mass and distance of OGLE-2014-BLG-0124L, making it the first microlensing planetary system with a space-based parallax measurement. The planet and star have masses of m similar to 0.5M(jup) and M similar to 0.7M(circle dot) and are separated by a(perpendicular to) similar to 3.1AU in projection. The main source of uncertainty in all of these numbers (approximately 30%, 30%, and 20%) is the relatively poor measurement of the Einstein radius theta(E), rather than uncertainty in pE, which is measured with 2.5% precision. This compares to 22% based on OGLE data alone, implying that the Spitzer data provide not only a substantial improvement in the precision of the pE measurement, but also the first independent test of a ground-based pE measurement.</P>
Microwave Absorption and Magnetic Properties of Cobalt Ferrites/Carbon Nanotubes Nanocomposites
B. B. Zhang,P. F. Wang,J. C. Xu,Y. B. Han,H. X. Jin,D. F. Jin,X. L. Peng,B. Hong,J. Li,J. Gong,H. L. Ge,Z. W. Zhu,X. Q. Wang 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2015 NANO Vol.10 No.5
Owing to the unique microstructure and the excellent dielectric properties, carbon nanotubes(CNTs) were decorated with CoFe2O4 nanoparticles to synthesize the CoFe2O4/CNTs nanocomposites by the solvothermal method. The phase structure, morphology, magnetic properties and microwave absorption performance of the as-prepared CoFe2O4/CNTs were characterized and discussed by X-ray diffraction (XRD), thermal gravity analysis (TGA), transmission electron microscope (TEM), vibrating sample magnetometer (VSM) and vector network analyzer (VNA). All results indicated that the diameter of CoFe2O4 nanoparticles decorating on the surface of CNTs increased with the solvothermal temperature. CoFe2O4/CNTs prepared at 180℃, 200℃ and 220℃ exhibited superparamagnetism, while the other samples presented ferromagnetism at room temperature. And with the increasing solvothermal temperature, the saturation magnetization and coercivity increased up to 72 emu/g and 2000 Oe for the sample prepared at 260℃ (S-26). And the reflection loss of CoFe2O4/CNTs nanocomposites increased with the solvothermal temperature up to -15.7 dB for S-26 with the bandwidth of 2.5 GHz.
다이캐스팅한 SiC 입자강화 알루미늄 복합재료의 피로균열 전파특성
김송희,윤여범,이기호,오준도,주희위,이지환 대한금속재료학회(대한금속학회) 1998 대한금속·재료학회지 Vol.36 No.8
This study is to investigate the effect of load ratio on fatigue crack of die-cast SiC particulate aluminum composites. Fundamental fatigue crack propagation tests were performed with sub-sized C-T specimens at a load ratio of 0.1, 0.3 and 0.5 respectively. Crack closure measurements were conducted for explaning the effect of load ratio on fatigue crack growth. The experimental results showed that the fatigue crack growth rate increases with the load ratio, especially at near threshold. The composite reinforced with 20 vol.% SiC particles was better in fatigue crack growth resistance than that with 10 vol.% SiC particles. Through the measurement of Kop and ΔK at various R ratios the concept of effective stress intensity factor range ratio. U was reviewed to evaluate the stress ratio effect on fatigue crack growth. Relationships between U and variables such as ΔK and R were obtained empirically so that we could predict ΔK_(eff) that is of critical importance for the prediction of fatigue crack propagation rate.