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Studies of TLP Dynamic Response Under Wind, Waves and Current 被引量:7
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作者 谷家扬 杨建民 吕海宁 《China Ocean Engineering》 SCIE EI 2012年第3期363-378,共16页
Investigated is the coupled response of a tension leg platform (TLP) for random waves. Inferred are the mass matrix, coupling stiffness matrix, damping matrix in the vibration differential equation and external load... Investigated is the coupled response of a tension leg platform (TLP) for random waves. Inferred are the mass matrix, coupling stiffness matrix, damping matrix in the vibration differential equation and external load of TLP in moving coordinating system. Infinitesimal method is applied to divide columns and pontoons into small parts. Time domain motion equation is solved by Runge-Kutta integration scheme. Jonswap spectrum is simulated in the random wave, current is simulated by linear interpolation, and NPD spectrum is applied as wind spectrum. The Monte Carlo method is used to simulate random waves and fluctuated wind. Coupling dynamic response, change of tendon tension and riser tension in different sea conditions are analyzed by power spectral density (PSD). The influence of approach angle on dynamic response of TLP and tendon tension is compared. 展开更多
关键词 TLP nonlinear stochastic waves sea state different approach angles coupling with wave current and wind
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Quantitative Surface Chirality Detection with Sum Frequency Generation Vibrational Spectroscopy: Twin Polarization Angle Approach
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作者 Feng Wei Yan-yan Xu +2 位作者 Yuan Guo Shi-lin Liu Hong-fei Wang 《Chinese Journal of Chemical Physics》 SCIE CAS CSCD 2009年第6期592-600,J0001,共10页
Here we report a novel twin polarization angle (TPA) approach in the quantitative chirality detection with the surface sum-frequency generation vibrational spectroscopy (SFG-VS). Generally, the achiral contributio... Here we report a novel twin polarization angle (TPA) approach in the quantitative chirality detection with the surface sum-frequency generation vibrational spectroscopy (SFG-VS). Generally, the achiral contribution dominates the surface SFG-VS signal, and the pure chiral signal is usually two or three orders of magnitude smaller. Therefore, it has been difficult to make quantitative detection and analysis of the chiral contributions to the surface SFG- VS signal. In the TPA method, by varying together the polarization angles of the incoming visible light and the sum frequency signal at fixed s or p polarization of the incoming infrared beam, the polarization dependent SFG signal can give not only direct signature of the chiral contribution in the total SFG-VS signal, but also the accurate measurement of the chiral and achiral components in the surface SFG signal. The general description of the TPA method is presented and the experiment test of the TPA approach is also presented for the SFG-VS from the S- and R-limonene chiral liquid surfaces. The most accurate degree of chiral excess values thus obtained for the 2878 cm^-1 spectral peak of the S- and R-limonene liquid surfaces are (23.7±0.4)% and (-25.4±1.3)%, respectively. 展开更多
关键词 Sum-frequency generation vibrational spectroscopy Twin polarization angle approach SURFACE CHIRALITY LIMONENE
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A new mixed type crack propagation criterion in shale reservoirs
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作者 Muru Ding Zhirong Jin +1 位作者 Yanjun Zhang Jinghong Hu 《Petroleum》 EI CSCD 2024年第1期85-92,共8页
Hydraulic fracturing is a mainstream technology for unconventional oil and gas reservoirs development all over the world.How to use this technology to achieve high-level oil and gas resource extraction and how to form... Hydraulic fracturing is a mainstream technology for unconventional oil and gas reservoirs development all over the world.How to use this technology to achieve high-level oil and gas resource extraction and how to form complex fracture networks as hydrocarbon transportation channels in tight reservoirs,which depends to a large extent on the interaction between hydraulic and pre-existing cracks.For hydraulic fracturing of fractured reservoirs,the impact of natural fractures,perforation direction,stress disturbances,faults and other influencing factors will produce a mixed I&II mode hydraulic fracture.To forecast whether hydraulic fractures cross pre-existing fractures,according to elastic mechanics and fracture mechanics,a stress state of cracks under the combination of tensile(I)and shear(II)is presented.A simple mixed-mode I&II hydraulic fracture's crossing judgment criterion is established,and the propagation of hydraulic fractures after encountering natural fractures is analyzed.The results show that for a given approaching angle there exists a certain range of stress ratio when crossing occurs.Under high approaching angle and large stress ratio,it is likely that hydraulic cracks will go directly through pre-existing cracks.The reinitiated angle is always controlled within the range of approximately 30among the main direction of penetration. 展开更多
关键词 Crack propagation criterion Stress ratio approaching angle Reinitiated angle Mechanical model
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Multiple Angles Of Approach
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作者 Li Li 《Beijing Review》 2013年第39期26-27,共2页
The Sixth Beijing Forum on Human Rights was held on September 12 and 13 with the theme being"construction of an environment for sustainable human rights development."The forum attracted more than100officialsandhuman... The Sixth Beijing Forum on Human Rights was held on September 12 and 13 with the theme being"construction of an environment for sustainable human rights development."The forum attracted more than100officialsandhumanrightsexpertsfromthe United Nations and 33 countries and regions. 展开更多
关键词 In Multiple angles Of Approach
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