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51.
Pasquale Tricarico 《Celestial Mechanics and Dynamical Astronomy》2008,100(4):319-330
We derive an expression for the mutual gravitational force and torque of two bodies having arbitrary shapes and mass distributions,
as an expansion in power series of their products of inertia and of the relative coordinates of their centres of mass. The
absolute convergence of all the power series developed is rigorously demonstrated. The absence of transcendental functions
makes this formalism suitable for fast numerical applications. The products of inertia used here are directly related to the
spherical harmonics coefficients, and we provide a detailed analysis of this relationship. 相似文献
52.
Giovanni Spagnoli 《Marine Georesources & Geotechnology》2017,35(4):578-585
Helical piles present a possible alternative to driven displacement piles in the offshore sector. While this type of pile is used widely in the onshore environment, design methods tend to be highly empirical and there is considerable uncertainty around the bearing resistance and the installation resistance required to install large diameter piles necessary to resist uplift. The paper combines a theoretical model for estimating torque resistance from the literature with a cone penetration test (CPT)-based model originally developed to estimate the axial resistance of helical piles and to predict the installation torque required to install piles in sand. The model appears to be able to capture the general installation behavior of piles across a range of scales and in various sand states. 相似文献
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F. Roosbeek 《Celestial Mechanics and Dynamical Astronomy》1999,74(4):243-252
In this paper, the series RDAN97 recently published (Roosbeek and Dehant, 1998) is completed by computing the diurnal and
subdiurnal nutation terms. The method used is based on computing the torque induced by the external bodies on the rigid earth.
The ephemerides used are analytical and based on celestial mechanics considerations. With a truncation level of 0.1 μas, 115
terms in longitude and 78 terms in obliquity have been computed. These terms correspond to the influence of the earth's geopotential
coefficients c2,2 and s2,2, c3,m and s3,m (for the interaction between the earth and the moon and the sun), and c4,m and s4,m (for the interaction between the earth and the moon). A comparison with the recent theories REN‐2000 (Souchay and Kinoshita,
1996, 1997) and SMART97 (Bretagnon et al., 1997, 1998) shows that our series is at a very high precision, better than the
most recent VLBI campaigns.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
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Giovanni Spagnoli Cristina de Hollanda Cavalcanti Tsuha 《Marine Georesources & Geotechnology》2020,38(9):1118-1120
AbstractA closure on the recent discussion regarding the review on the behavior of helical piles as a potential offshore foundation system by the Authors is presented. Installation torque, uplift capacity, installation effects, model pile, installation speed and results proposed by Discussers are commented. 相似文献
60.
Kern E. Kenyon 《Journal of Oceanography》2006,62(6):923-927
Surface gravity waves are commonly observed to slow down and to stop at a beach without any noticeable reflection taking place.
We assume that as a consequence the waves are continuously giving up their linear and angular momenta, which they carry with
them, along with energy, as they propagate into gradually decreasing mean depths of water. It takes a force to cause a time
rate of decrease in the linear momentum and a torque to produce a time rate of decrease in the angular momentum. Both a force
and a torque operate on the shoaling waves, due to the presence of the sloping bottom, to cause the diminution of their linear
and angular momenta. By Newton’s third law, action equals reaction, an equal but opposite force and torque are exerted on
the bottom. No other mechanisms for transferring linear and angular momenta are included in the model. Since the force on
the waves acts over a horizontal distance during shoaling, work is done on the waves and energy flux is not conserved. Bottom
friction, wave interaction with a mean flow, scattering from small-scale bottom irregularities and set-up are neglected. Mass
flux is conserved, which leads to a shoreward monotonic decrease in amplitude consistent with available swell data. The formula
for the time-independent force on the bottom agrees qualitatively with observations in seven different ways: four for swell
attenuation and three for sediment transport on beaches. Ardhuin (2006) argues against a mean force on the bottom that is
not hydrostatic, mainly by using conservation of energy flux. He also applies the action balance equation to shoaling waves.
Action is a difficult concept to grasp for motion in a continuum; it cannot be easily visualized, and it is not really necessary
for solving the shoaling wave problem. We prefer angular momentum because it is clearly related to the observed orbital motion
of the fluid particles in progressive surface waves. The physical significance of wave action for surface waves has been described
recently by showing that in deep water action is equivalent to the magnitude of the wave’s orbital angular momentum (Kenyon
and Sheres, 1996). Finally, Ardhuin requires that there be a significant exchange of linear momentum between shoaling waves
and an unspecified mean flow, although the magnitude and direction of the exchange are not predicted. No mention is made of
what happens to the orbital angular momentum during shoaling. Mass flux conservation is not stated. 相似文献