Academic literature on the topic 'Earth (planet), rotation'
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Journal articles on the topic "Earth (planet), rotation"
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Velgas, Lev Borisovich, and Liia Lvovna Iavolinskaia. "Seven main discoveries, rigorously proven." Interactive science, no. 6 (40) (June 21, 2019): 103–5. http://dx.doi.org/10.21661/r-496981.
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We are striving to prove that all planets rotate around their axis due to their satellites. Rotation of the collateral gravitation is analogous for all the planets, for the Sun as well. The Sun, as well as every single planet, can have multiple satellites. Satellite and planet’s collateral gravitation, if it moves because of satellite’s movement around the orbit, rotates the planet or the Sun. The article proves that collateral gravitation of the Moon and the Earth, that moves around the Earth due to Moon’s movement around the Earth, rotates the Earth around it’s axis.
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Bolmont, E., S. N. Breton, G. Tobie, C. Dumoulin, S. Mathis, and O. Grasset. "Solid tidal friction in multi-layer planets: Application to Earth, Venus, a Super Earth and the TRAPPIST-1 planets." Astronomy & Astrophysics 644 (December 2020): A165. http://dx.doi.org/10.1051/0004-6361/202038204.
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With the discovery of TRAPPIST-1 and its seven planets residing within 0.06 au, it is becoming increasingly necessary to carry out correct treatments of tidal interactions. The eccentricity, rotation, and obliquity of the planets of TRAPPIST-1 do indeed result from the tidal evolution over the lifetime of the system. Tidal interactions can also lead to tidal heating in the interior of the planets (as for Io), which may then be responsible for volcanism or surface deformation. In the majority of studies aimed at estimating the rotation of close-in planets or their tidal heating, the planets are considered as homogeneous bodies and their rheology is often taken to be a Maxwell rheology. Here, we investigate the impact of taking into account a multi-layer structure and an Andrade rheology in the way planets dissipate tidal energy as a function of the excitation frequency. We use an internal structure model, which provides the radial profile of structural and rheological quantities (such as density, shear modulus, and viscosity) to compute the tidal response of multi-layered bodies. We then compare the outcome to the dissipation of a homogeneous planet (which only take a uniform value for shear modulus and viscosity). We find that for purely rocky bodies, it is possible to approximate the response of a multi-layer planet by that of a homogeneous planet. However, using average profiles of shear modulus and viscosity to compute the homogeneous planet response leads to an overestimation of the averaged dissipation. We provide fitted values of shear modulus and viscosity that are capable of reproducing the response of various types of rocky planets. However, we find that if the planet has an icy layer, its tidal response can no longer be approximated by a homogeneous body because of the very different properties of the icy layers (in particular, their viscosity), which leads to a second dissipation peak at higher frequencies. We also compute the tidal heating profiles for the outer TRAPPIST-1 planets (e to h).
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Orlov, S. "Genesis of the Planet Earth." Journal of Advance Research in Applied Science (ISSN: 2208-2352) 3, no. 2 (February 29, 2016): 27–37. http://dx.doi.org/10.53555/nnas.v3i2.661.
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This article is based on the theory of vortex gravitation and physical abnormalities of the Earth slowing its rotation. Defined orbital acceleration, weight, approach to the Sun and the age of our planet. Offered to justify the creation of planetary material in the center of the Earth torsion, and not as the accumulation of cosmic dust and meteorites from outer space.
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Orlov, R. S. "Genesis of the Planet Earth." Evolving Trends in Engineering and Technology 5 (April 2015): 1–10. http://dx.doi.org/10.18052/www.scipress.com/etet.5.1.
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This article is based on the theory of vortex gravitation and physical abnormalities of the Earth - slowing its rotation. Defined orbital acceleration, weight, approach to the Sun and the age of our planet. Offered to justify the creation of planetary material in the center of the Earth torsion, and not as the accumulation of cosmic dust and meteorites from outer space.
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Orlov, Sergey. "Genesis of the Planet Earth." International Letters of Chemistry, Physics and Astronomy 54 (July 2015): 37–46. http://dx.doi.org/10.18052/www.scipress.com/ilcpa.54.37.
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This article is based on the theory of vortex gravitation and physical abnormalities of the Earth - slowing its rotation. Defined orbital acceleration, weight, approach to the Sun and the age of our planet. Offered to justify the creation of planetary material in the center of the Earth torsion, and not as the accumulation of cosmic dust and meteorites from outer space.
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Orlov, R. S. "Genesis of the Planet Earth." International Journal of Engineering and Technologies 5 (April 1, 2015): 1–10. http://dx.doi.org/10.56431/p-6fzs83.
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This article is based on the theory of vortex gravitation and physical abnormalities of the Earth - slowing its rotation. Defined orbital acceleration, weight, approach to the Sun and the age of our planet. Offered to justify the creation of planetary material in the center of the Earth torsion, and not as the accumulation of cosmic dust and meteorites from outer space.
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Orlov, Sergey. "Genesis of the Planet Earth." International Letters of Chemistry, Physics and Astronomy 54 (July 3, 2015): 37–46. http://dx.doi.org/10.56431/p-08pr4l.
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This article is based on the theory of vortex gravitation and physical abnormalities of the Earth - slowing its rotation. Defined orbital acceleration, weight, approach to the Sun and the age of our planet. Offered to justify the creation of planetary material in the center of the Earth torsion, and not as the accumulation of cosmic dust and meteorites from outer space.
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Su, W. j., A. M. Dziewonski, and R. Jeanloz. "Planet Within a Planet: Rotation of the Inner Core of Earth." Science 274, no. 5294 (December 13, 1996): 1883–87. http://dx.doi.org/10.1126/science.274.5294.1883.
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Rao, Suvrat, Georges Meynet, Patrick Eggenberger, Lionel Haemmerlé, Giovanni Privitera, Cyril Georgy, Sylvia Ekström, and Christoph Mordasini. "Star-planet interactions." Astronomy & Astrophysics 618 (October 2018): A18. http://dx.doi.org/10.1051/0004-6361/201833107.
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Context. When planets are formed from the protoplanetary disk and after the disk has dissipated, the evolution of their orbits is governed by tidal interactions, friction, and gravitational drag, and also by changes in the mass of the star and planet. These interactions may change the initial distribution of the distances between the planets and their host star by expanding the original orbit, by contracting it (which may cause an engulfment of the planet by the star), or by destroying the planet. Aims. We study the evolution of the orbit of a planet orbiting its host star under the effects of equilibrium tides, dynamical tides, drag (frictional and gravitational), and stellar mass loss. Methods. We used the Geneva stellar evolution code to compute the evolution of stars with initial masses of 1 and 1.5 M⊙ with different rotation rates at solar metallicity. The star is evolved from the pre-main-sequence (PMS) up to the tip of the red giant branch. We used these models as input for computing the evolution of the planetary orbits. We explored the effects of changing the planet masses (of 1 Earth mass up to 20 Jupiter masses), the distance between the planet and the star (of 0.015 and more than 3 au), the mass, and the spin of the star. We present results when only the equilibrium tide was accounted for and when both equilibrium and dynamical tides were accounted for. The expression for the dynamical tide is a frequency-averaged dissipation of tidally excited inertial waves, obtained from a piecewise homogeneous two-layer stellar model. Gravity wave damping was neglected. Results. Dynamical tides in convective zones have a significant effect on planetary orbits only during the PMS phase and only for fast-rotating stars. They have no significant effects during the PMS phase for initially slow-rotating stars and during the red giant branch phase, regardless of the initial rotation. In the plots of initial orbital distance versus planetary mass, we show the regions that lead to engulfment or any significant changes in the orbit. As a result of orbital evolution, a region near the star can become devoid of planets after the PMS phase. We call this zone the planet desert, and its extent depends sensitively on stellar rotation. An examination of the planet distribution as a function of distance to the host star and mass can provide constraints on current computations.
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Lyu, Xintong, Daniel D. B. Koll, Nicolas B. Cowan, Renyu Hu, Laura Kreidberg, and Brian E. J. Rose. "Super-Earth LHS3844b is Tidally Locked." Astrophysical Journal 964, no. 2 (March 28, 2024): 152. http://dx.doi.org/10.3847/1538-4357/ad2077.
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Abstract Short-period exoplanets on circular orbits are thought to be tidally locked into synchronous rotation. If tidally locked, these planets must possess permanent day- and night-sides, with extreme irradiation on the dayside and none on the nightside. However, so far the tidal locking hypothesis for exoplanets is supported by little to no empirical evidence. Previous work showed that the super-Earth LHS 3844b likely has no atmosphere, which makes it ideal for constraining the planet’s rotation. Here we revisit the Spitzer phase curve of LHS 3844b with a thermal model of an atmosphere-less planet and analyze the impact of nonsynchronous rotation, eccentricity, tidal dissipation, and surface composition. Based on the lack of observed strong tidal heating we rule out rapid nonsynchronous rotation (including a Mercury-like 3:2 spin–orbit resonance) and constrain the planet's eccentricity to less than ∼0.001 (more circular than Io's orbit). In addition, LHS 3844b’s phase curve implies that the planet either still experiences weak tidal heating via a small-but-nonzero eccentricity (requiring an undetected orbital companion), or that its surface has been darkened by space weathering; of these two scenarios we consider space weathering more likely. Our results thus support the hypothesis that short-period rocky exoplanets are tidally locked, and further show that space weathering can significantly modify the surfaces of atmosphere-less exoplanets.
Dissertations / Theses on the topic "Earth (planet), rotation"
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Kaspi, Yohai. "Turbulent convection in the anelastic rotating sphere : a model for the circulation on the giant planets." Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/45780.
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Thesis (Ph. D.)--Joint Program in Physical Oceanography (Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences; and the Woods Hole Oceanographic Institution), 2008.Includes bibliographical references (p. 207-221).
This thesis studies the dynamics of a rotating compressible gas sphere, driven by internal convection, as a model for the dynamics on the giant planets. We develop a new general circulation model for the Jovian atmosphere, based on the MITgcm dynamical core augmenting the nonhydrostatic model. The grid extends deep into the planet's interior allowing the model to compute the dynamics of a whole sphere of gas rather than a spherical shell (including the strong variations in gravity and the equation of state). Different from most previous 3D convection models, this model is anelastic rather than Boussinesq and thereby incorporates the full density variation of the planet. We show that the density gradients caused by convection drive the system away from an isentropic and therefore barotropic state as previously assumed, leading to significant baroclinic shear. This shear is concentrated mainly in the upper levels and associated with baroclinic compressibility effects. The interior flow organizes in large cyclonically rotating columnar eddies parallel to the rotation axis, which drive upgradient angular momentum eddy fluxes, generating the observed equatorial superrotation. Heat fluxes align with the axis of rotation, contributing to the observed flat meridional emission. We show the transition from weak convection cases with symmetric spiraling columnar modes similar to those found in previous analytic linear theory, to more turbulent cases which exhibit similar, though less regular and solely cyclonic, convection columns which manifest on the surface in the form of waves embedded within the superrotation. We develop a mechanical understanding of this system and scaling laws by studying simpler configurations and the dependence on physical properties such as the rotation period, bottom boundary location and forcing structure. These columnar cyclonic structures propagate eastward, driven by dynamics similar to that of a Rossby wave except that the restoring planetary vorticity gradient is in the opposite direction, due to the spherical geometry in the interior.
(cont.) We further study these interior dynamics using a simplified barotropic annulus model, which shows that the planetary vorticity radial variation causes the eddy angular momentum flux divergence, which drives the superrotating equatorial flow. In addition we study the interaction of the interior dynamics with a stable exterior weather layer, using a quasigeostrophic two layer channel model on a beta plane, where the columnar interior is therefore represented by a negative beta effect. We find that baroclinic instability of even a weak shear can drive strong, stable multiple zonal jets. For this model we find an analytic nonlinear solution, truncated to one growing mode, that exhibits a multiple jet meridional structure, driven by the nonlinear interaction between the eddies. Finally, given the density field from our 3D convection model we derive the high order gravitational spectra of Jupiter, which is a measurable quantity for the upcoming JUNO mission to Jupiter.
by Yohai Kaspi.
Ph.D.
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Meiss, Helmut. "Diversifying crop rotations with temporary grasslands : potentials for weed mangement and farmland biodiversity." Phd thesis, Université de Bourgogne, 2010. http://tel.archives-ouvertes.fr/tel-00575607.
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Crop rotation may be used to prevent the continuous selection of particular weed species adapted to one crop type. This might be useful for weed management, economy in herbicide applications and promoting biodiversity. Common simple crop sequences might be diversified by introducing perennial forage crops. Impacts of such perennial crops on weeds were studied with four approaches : 1) Large-scale weed surveys in 632 fields in western France showed that weed species composition differed most strongly between perennial alfalfa crops and annual crops. Comparisons of fields before, during and after perennial alfalfa suggested that community composition varies in a cyclic way during such crop rotations. Several weed species problematic in annual crops were suppressed during and after perennial crops, but the appearance of other species led to equal or even higher plant diversities. 2) A 3-year field experiment with contrasting crop management options allowed an investigation of the underlying mechanisms for this: The absence of soil tillage reduced weed emergence but increased the survival of established plants. The permanent vegetation cover and frequent hay cuttings reduced weed growth, plant survival and seed production. 3) Greenhouse experiments testing the regrowth ability of individual plants after cutting showed strong differences between species and functional groups. An two-factorial experiment suggested that the negative impacts of cutting and competition on weed growth were mainly additive. 4) Special measurements of weed seed predation in the field experiment showed positive correlations with vegetation cover, indicating that this ecosystem service may be particularly fostered by perennial crops. Consistent preferences of seed predators for certain weed species indicates that seed predation may be another cause of the observed weed community shifts.
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Steinmoeller, Derek. "Flow Separation on the β-plane." Thesis, 2009. http://hdl.handle.net/10012/4417.
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In non-rotating fluids, boundary-layer separation occurs when the nearly inviscid flow just outside a viscous boundary-layer experiences an appreciable deceleration due to a region of adverse pressure gradient. The fluid ceases to flow along the boundary due to a flow recirculation region close to the boundary. The flow is then said to be "detached."
In recent decades, attention has shifted to the study of boundary-layer separation in a rotating reference frame due to its significance in Geophysical Fluid Dynamics (GFD). Since the Earth is a rotating sphere, the so-called β-plane approximation f = f0 + βy is often used to account for the inherent meridional variation of the Coriolis parameter, f, while still solving the governing equations on a plane. Numerical simulations of currents on the β-plane have been useful in understanding ocean currents such as the Gulf Stream, the Brazil Current, and the Antarctic Circumpolar Current to name a few.
In this thesis, we first consider the problem of prograde flow past a cylindrical obstacle on the β-plane. The problem is governed by the barotropic vorticity equation and is solved using a numerical method that is a combination of a finite difference method and a spectral method. A modified form of the β-plane approximation is proposed to avoid computational difficulties. Results are given and discussed for flow past a circular cylinder at selected Reynolds numbers (Re) and non-dimensional β-parameters (β^). Results are
then given and discussed for flow past an elliptic cylinder of a fixed aspect ratio (r = 0.2) and at two angles of inclination (90°, 15°) at selected Re and β^. In general, it is found that the β-effect acts to suppress boundary-layer separation and to allow Rossby waves to form in the exterior flow field. In the asymmetrical case of an inclined elliptic cylinder, the β-effect was found to constrain the region of vortex shedding to a small region near the trailing edge of the cylinder. The shed vortices were found to propagate around the trailing edge instead of in the expected downstream direction, as observed in the non-rotating case.
The second problem considered in this thesis is the separation of western boundary currents from a curved coastline. This problem is also governed by the barotropic vorticity equation, and it is solved on an idealized model domain suitable for investigating the effects that boundary curvature has on the tendency of a boundary current to separate. The numerical method employed is a two-dimensional Chebyshev spectral collocation method and yields high order accuracy that helps to better resolve the boundary-layer dynamics in comparison to low-order methods. Results are given for a selection of boundary curvatures, non-dimensional β-parameters (β^), Reynolds numbers (Re), and Munk Numbers (Mu). In general, it is found than an increase in β^ will act to suppress boundary-layer separation. However, a sufficiently sharp obstacle can overcome the β-effect and force the boundary current to separate regardless of the value of β^. It is also found that in the inertial limit (small Mu, large Re) the flow region to the east of the primary boundary current is dominated by strong wave interactions and large eddies which form as a result of shear instabilities. In an interesting case of the inertial limit, strong waves were found to interact with the separation region, causing it to expand and propagate to the east as a large eddy. This idealized the mechanism by which western
boundary currents such as the Gulf Stream generate eddies in the world's oceans.
Books on the topic "Earth (planet), rotation"
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1930-, Mueller Ivan Istvan, ed. Earth rotation: Theory and observation. New York: Ungar, 1987.
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NATO Advanced Research Workshop on Earth Rotation: Solved and Unsolved Problems (1985 Gers, France). Earth rotation--solved and unsolved problems. Dordrecht: D. Reidel Pub. Co., 1986.
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Hicks, Terry Allan. Why does the sun set? New York: Marshall Cavendish Benchmark, 2010.
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Stig, Flodmark, and Symposium on Geomagnetism Earth Rotation and Related Problems (1988 : Stockholm, Sweden), eds. New approaches in geomagnetism and the earth's rotation: Stockholm, Sweden, 10-12 October 1988. Singapore: World Scientific, 1991.
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Stewart, Melissa. Why do seasons change? New York: Marshall Cavendish Benchmark, 2006.
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Langel, R. A. The magnetic field of the Earth's lithosphere: The satellite perspective. Cambridge, U.K: Cambridge University Press, 1998.
Find full textBook chapters on the topic "Earth (planet), rotation"
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Sabadini, Roberto, and Bert Vermeersen. "Rotational Dynamics of Viscoelastic Planets." In Global Dynamics of the Earth, 99–126. Dordrecht: Springer Netherlands, 2004. http://dx.doi.org/10.1007/978-94-017-1709-0_3.
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Bertotti, Bruno, and Paolo Farinella. "The Rotation of the Earth and Other Planets." In Physics of the Earth and the Solar System, 45–73. Dordrecht: Springer Netherlands, 1990. http://dx.doi.org/10.1007/978-94-009-1916-7_3.
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Mémin, Etienne, Long Li, Noé Lahaye, Gilles Tissot, and Bertrand Chapron. "Linear Wave Solutions of a Stochastic Shallow Water Model." In Mathematics of Planet Earth, 223–45. Cham: Springer Nature Switzerland, 2023. http://dx.doi.org/10.1007/978-3-031-40094-0_10.
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AbstractIn this paper, we investigate the wave solutions of a stochastic rotating shallow water model. This approximate model provides an interesting simple description of the interplay between waves and random forcing ensuing either from the wind or coming as the feedback of the ocean on the atmosphere and leading in a very fast way to the selection of some wavelength. This interwoven, yet simple, mechanism explains the emergence of typical wavelength associated with near inertial waves. Ensemble-mean waves that are not in phase with the random forcing are damped at an exponential rate, whose magnitude depends on the random forcing variance. Geostrophic adjustment is also interpreted as a statistical homogenization process in which, in order to conserve potential vorticity, the small-scale component tends to align to the velocity fields to form a statistically homogeneous random field.
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Sabadini, Roberto, and Bert Vermeersen. "Tectonics and the Rotation of the Earth and Terrestrial Planets." In Global Dynamics of the Earth, 227–67. Dordrecht: Springer Netherlands, 2004. http://dx.doi.org/10.1007/978-94-017-1709-0_7.
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Sabadini, Roberto, Bert Vermeersen, and Gabriele Cambiotti. "Rotational Dynamics of Viscoelastic Planets: Linear Theory." In Global Dynamics of the Earth: Applications of Viscoelastic Relaxation Theory to Solid-Earth and Planetary Geophysics, 87–148. Dordrecht: Springer Netherlands, 2016. http://dx.doi.org/10.1007/978-94-017-7552-6_3.
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Gay, J., Y. Rabbia, and C. Manghini. "Interfero-Coronagraphy Using Pupil π-Rotation." In Infrared Space Interferometry: Astrophysics & the Study of Earth-Like Planets, 187–90. Dordrecht: Springer Netherlands, 1997. http://dx.doi.org/10.1007/978-94-011-5468-0_25.
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Paldor, Nathan. "Waves in a Channel on the Equatorial β-Plane." In Shallow Water Waves on the Rotating Earth, 29–34. Cham: Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-20261-7_3.
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Paldor, Nathan. "Waves in a Channel on the Mid-latitude β-Plane." In Shallow Water Waves on the Rotating Earth, 13–27. Cham: Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-20261-7_2.
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Huntley, David, Drew Rotheram-Clarke, Kelvin Sattler, and David Elwood. "Surficial Geology and Geomorphology of the North Slide, Thompson River Valley, British Columbia, Canada: Application of Fundamental Geoscience Information to Interpretations of Geospatial Monitoring Results." In Progress in Landslide Research and Technology, 221–38. Cham: Springer Nature Switzerland, 2023. http://dx.doi.org/10.1007/978-3-031-44296-4_10.
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AbstractOur study focuses on a slow-moving landslide in the Thompson River valley, south-central British Columbia, Canada, that has posed a hazard to the national railway transportation corridor since 1880. Real-time kinematic global navigation satellite systems, unoccupied aerial vehicles, and satellite synthetic aperture radar interferometry time-series show significant displacement encroaching on railway infrastructure. In this paper, geospatial relationships between landslide distribution and specific terrain features, and the environmental conditions triggering instability are determined from field-based geological observations. We describe how earth material stratigraphy, textures, and penetrative planar structures are important controls on sub-surface drainage, and how these factors influence the style, timing, and rate of slope displacement. West of the railway tracks, slide scarps extend across the toe slope, corresponding to narrow zones of high displacement, presence of perennial springs and seepage, and cutbank erosion along the river channel. Fluvial incision exposes weak, failure-prone units at the base of the fill sequence, and with ongoing channel migration promotes instability by altering landslide toe geometry. Currently, the zone of potential displacement does not extend upslope into the inactive (1880) main slide body, east of the tracks. Seasonal variations in hydrogeological conditions influence the spatial and temporal patterns of surface water and groundwater flow, in turn controlling the distribution of translational-rotational displacement of slide blocks, and rates of movement on reactivated shear surfaces that extend under Thompson River. Slope failure occurs along weak, sub-horizontal shear zones within poorly drained glaciolacustrine clay and silt units, overlain by rapidly drained glaciofluvial outwash gravel, and imperfectly drained till diamicton. River levels exert a complex control on landslide stability, influencing hydraulic gradients within the basal glaciolacustrine unit, particularly along rupture surfaces within it. Ground displacement occurs while river levels are at their lowest between February and March, before peak flows in June, or after July until December while storm-fed river levels progressively lower to the next winter minimum. Groundwater levels remain elevated in the slide body throughout the year, contained in porous gravel and sand beds, and along brittle fractures and sub-horizonal shear zones in silt-clay varve beds. Geospatial and temporal change-detection monitoring of active landslides and at-risk infrastructure, when benchmarked with terrain and hydrogeological observations, is a cost-effective hazard management practice that provides important geoscience information to help develop appropriate early warning, mitigation, adaptation, and risk reduction measures.
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Lowrie, William. "2. Planet Earth." In Geophysics: A Very Short Introduction, 6–21. Oxford University Press, 2018. http://dx.doi.org/10.1093/actrade/9780198792956.003.0002.
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Two important physical laws determine the behaviour of the Earth as a planet and the relationship between the Sun and its planets: the law of conservation of energy and the law of conservation of angular momentum. ‘Planet Earth’ explains these laws along with the ‘Big Bang’ theory that describes the formation of the solar system: the Sun; the eight planets divided into the inner, terrestrial planets (Mercury, Venus, the Earth, and Mars) and the outer, giant planets (Jupiter, Saturn, Uranus, and Neptune); and the Trans-Neptunian objects that lie beyond Neptune. Kepler’s laws of planetary motion, the Chandler wobble, the effects of the Moon and Jupiter on the Earth’s rotation, and the Milankovitch cycles of climatic variation are also discussed.
Conference papers on the topic "Earth (planet), rotation"
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Scholl, Marija S. "Star-Light Suppression with a rotating Rotational-Shearing Interferometer for Extra-Solar Planet Detection." In Signal Recovery and Synthesis. Washington, D.C.: Optica Publishing Group, 1995. http://dx.doi.org/10.1364/srs.1995.rtue2.
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Star light, scattered from even most smoothly polished optical surfaces, prevents detection of a faint planet light because of the enormous brightness ratio between them. Figure 1 shows two point sources: a dark (Earth-like) planet rotates slowly around a bright star. At the time of observation the planet is assumed to be on x-axis. The wavefronts originating from the star and the planet, respectively, are incident on the aperture at a distant observation plane as plane waves with the propagation vector parallel to the optical axis and tilted with the direction cosine vector (1, 0, n).
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Borom, Marcus P. "ROLE OF EARTH-MOON ROTATIONAL DYNAMICS IN THE SHAPING OF THE SURFACE OF OUR PLANET." In GSA Annual Meeting in Phoenix, Arizona, USA - 2019. Geological Society of America, 2019. http://dx.doi.org/10.1130/abs/2019am-330485.
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Fluckiger, Patrick, Ilan Vardi, and Simon Henein. "Design of a Flexure Based Low Frequency Foucault Pendulum." In ASME 2020 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/detc2020-22075.
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Abstract The Foucault pendulum is a well-known mechanism used to demonstrate the rotation of the Earth. It consists in a pendulum launched on linear orbits and, following Mach’s Principle, this line of oscillation will remain fixed with respect to absolute space but appear to slowly precess for a terrestrial observer due to the turning of the Earth. The theoretical proof of this phenomenon uses the fact that, to first approximation, the Foucault pendulum is a harmonic isotropic two degree of freedom (2-DOF) oscillator. Our interest in this mechanism follows from our research on flexure-based implementations of 2-DOF oscillators for their application as time bases for mechanical timekeeping. The concept of the Foucault pendulum therefore applies directly to 2-DOF flexure based harmonic oscillators. In the Foucault pendulum experiment, the rotation of the Earth is not the only source of precession. The unavoidable defects in the isotropy of the pendulum along with its well-known intrinsic isochronism defect induce additional precession which can easily mask the precession due to Earth rotation. These effects become more prominent as the frequency increases, that is, when the length of the pendulum decreases. For this reason, short Foucault pendulums are difficult to implement, museum Foucault pendulum are typically at least 7 meters long. These effects are also present in our flexure based oscillators and reducing these parasitic effects, requires decreasing their frequency. This paper discusses the design and dimensioning of a new flexure based 2-DOF oscillator which can reach low frequencies of the order of 0.1[Hz]. The motion of this oscillator is approximately planar, like the classical Foucault pendulum, and will have the same Foucault precession rate. The construction of a low frequency demonstrator is underway and will be followed by quantitative measurements which will examine both the Foucault effect as well as parasitic precession.
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Kaluthantrige Don, Aurelio, Jinglang Feng, and Jesús Gil-Fernández. "Pose estimation of chaotic motion of Didymos' moon using CNN-based Image Processing algorithm." In ESA 12th International Conference on Guidance Navigation and Control and 9th International Conference on Astrodynamics Tools and Techniques. ESA, 2023. http://dx.doi.org/10.5270/esa-gnc-icatt-2023-156.
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The Asteroid Impact and Deflection Assessment (AIDA) is an international collaboration between the European Space Agency (ESA) and the National Aeronautics and Space Administration (NASA) aiming to investigate the binary asteroid system(65803) Didymos and to demonstrate asteroid deflection technique with kinetic impact. NASA’s Double Asteroid Redirection Test (DART) mission successfully impacted Dimorphos, the moon of the binary system, in September 2022. ESA’s contribution is the Hera mission that will rendezvous with Didymos and observe the impact effects closely. The Close Observation Phase (COP) is the proximity operation of Hera mission with the objective of obtaining high-resolution images of Dimorphos and fully characterizing the impact crater. Autonomous optical navigation system is designed for this phase based on line-of-sight and range measurements from both the primary body and Dimorphos in order to estimate the relative position of the spacecraft. The close distance between the primary and the spacecraft during the COP allows the implementation of feature tracking relative navigation to solve the primary’s relative attitude. Nevertheless, the relative attitude of Dimorphos remains unsolved as it requires closer distance. This paper develops an innovative methodology to estimate the continuous six degree of freedom pose (position and attitude) of Dimorphos during the COP using a Convolutional Neural Networks (CNN)-based Image Processing (IP) algorithm. For the attitude, we implement an appearance-based method that consists of two stages. In the first stage, we use CNNs with the images captured by the spacecraft on-board camera to regress a set of keypoints segmenting Dimorphos from its background. In the second stage, we use Neural Networks (NN) to map these keypoints to the three Euler angles representing the relative rotation matrix of Dimorphos with respect to the spacecraft. The estimated keypoints are also used to estimate the position of the centroid of Dimorphos and its relative distance with respect to the spacecraft, which together provides the relative position vector of the spacecraft. For the distance, the shape of Dimorphos is approximated to an ellipse of size and shape depending on its relative attitude with respect to the spacecraft. The regressed keypoints are used to evaluate the apparent semi-minor and semi-major axes of Dimorphos, which are used to estimate the range from the spacecraft using the pinhole camera model. The High-Resolution Network (HRNet) is used as CNN architecture as it represents the state-of-the-art technology in keypoint detection with its capability of maintaining high resolution representations of the input images by connecting multiple subnetworks in parallel. For attitude navigation, the appearance-based method is selected for three main reasons. Firstly, it has the main advantage of a reduced dependency on the distance that is the main driver for a feature tracking relative navigation technique. Secondly, other methods such as model-based ones require sufficiently regular shapes of the targets, which is not the case of near-earth objects such as asteroids. Thirdly, the appearance-based method does not depend on prior knowledge of spinning axis and rate of the target, which appears to be chaotic for Dimorphos after the impact with DART. The training, validation and testing datasets consist of synthetic images generated with the software Planet and Asteroid Natural scene Generation Utility (PANGU) at different epochs of the COP trajectory provided by ESA. Additional images generated from different trajectory segments around the binary system are used to augment the training database. Therefore, our develop algorithm is expected to solve the overall pose estimation and improve the efficiency and the robustness of the autonomous navigation of the proximity operations of Hera mission.
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Nagarjun, Y. "Earth Potential Rise influence on High-Voltage rotating machines of a power plant caused due to lightning on a nearby tall object." In 2014 International Conference on Lightning Protection (ICLP). IEEE, 2014. http://dx.doi.org/10.1109/iclp.2014.6971988.
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Itoh, Y., and T. Suzuki. "Magnetic and Magneto-optical Properties of TbFeCo/Pt and TbFeCo/NdCo Multilayers." In Optical Data Storage. Washington, D.C.: Optica Publishing Group, 1998. http://dx.doi.org/10.1364/ods.1998.pdp.2.
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The optimization of novel materials for short wavelength magneto-optical recording is key for future high density recording. TbFeCo amorphous films currently used exhibit a substantial reduction in Kerr activity with decreasing wavelength [1], and therefore, it is desirable to enhance it by adding some element. Polarized Pt atoms are known to enhance the magneto-optical effect at short wavelengths, as demonstrated in Co/Pt multilayers [2]-[4], NdFeCo films also show the increase of the Kerr rotation angle at such wavelengths [5], [6], Accordingly, TbFeCo films containing Pt or Nd are potential candidates for future short wavelength recording media. However, very little systematic studies have been carried out to examine the effect of Pt in rare-earth transition-metal (RE-TM) amorphous films [7], [8]. And Nd-TM alloy has a problem that the films generally show in-plane magnetization, although the high perpendicular magnetic anisotropy must be taken into consideration in practical use. In order to achieve high Kerr activity at short wavelengths with a high perpendicular anisotropy, multilayers such as TbFeCo/Pt and TbFeCo/NdCo were fabricated. The present study aims to understand the roles of Pt and NdCo layer in TbFeCo on both magnetic and magneto-optical properties.
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Sivarapu, Aditya Krishna, and Hong Zhou. "Solar Trackers Using Spherical Mechanisms." In ASME 2023 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2023. http://dx.doi.org/10.1115/imece2023-113087.
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Abstract The power harvesting from a solar panel is maximized when its face is perpendicular to the solar ray. In order for a solar panel to face the sun during the daytime, its orientation has to be adjusted by a solar tracker. There are two relative motions between earth and sun. Compared with its daily east to west rotation, sun’s south-north movement is much smaller. If only sun’s east-west relative motion is considered for developing solar trackers, mechanisms with single degree of freedom can be adopted. If the orientation of a solar tracker with single degree of freedom is adjusted seasonally or monthly to cover sun’s small south-north relative movement, the solar tracker can effectively fulfill its solar tracking function. Single-axis solar trackers commonly consume less power to operate than their two-axis counterparts and cost less to fabricate and maintain, which brings their solar tracking merits. This research is on single-axis solar tracking mechanisms that are based on four-bar mechanisms. Because of their simple structure, high reliability, and easy maintenance, four-bar mechanisms have been extensively employed for various applications that include solar tracking. Four-bar solar tracking mechanisms currently have room for further improvement. The difficulties facing them include limited solar tracking motion, high solar tracking power consumption, and lacking self-locking function. Surmounting these difficulties makes designing four-bar solar tracking mechanisms challenging. Four-bar solar tracking mechanisms can be planar 4R, planar 3R1P, spherical four-bar mechanisms. Each of the three types has its unique solar tracking features. In this research, the performances of these four-bar solar tracking mechanisms are analyzed, simulated and compared with the motivation of improving them. The research results are tried to provide some guidelines for developing and promoting four-bar solar trackers.
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Mao, Y., H. A. Macleod, and K. Balasubramanian. "Optical Constant Determination of Magneto-optical Thin Film Using Surface Plasmon Resonance Phenomenon." In Optical Interference Coatings. Washington, D.C.: Optica Publishing Group, 1988. http://dx.doi.org/10.1364/oic.1988.wc17.
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Recent research identifies amorphous rare-earth-transition-metal thin films as most promising magneto-optical (MO) erasable storage materials. While writing is achieved by thermomagnetic means, reading is performed using polar Kerr magneto-optic effects. Generally the polar Kerr effect of MO films is quite small, being a fraction of a degree in rotation of polarization. Multiple dielectric protective layers can also enhance the magneto-optic Kerr effect [1,2]. The refractive index n and extinction coefficient k are required for the design of multilayer structures but little data exists for magneto-optical materials. We developed a method to measure the optical constants using the surface plasmon resonance phenomenon, which is based on the high sensitivity of that resonance to the optical constants [3,4], The configuration is shown in Fig.l. Light polarized with electric field parallel to the plane of incidence (TM) is incident within the glass upon the inside surface of the MO thin film. At angles of incidence greater than the critical angle for total reflection, an evanescent wave penetrates the metal and excites the natural modes of oscillation of the density of electrons at the surface of the MO film. At certain angle of incidence such that the component of the optical wave vector parallel to the metal surface is equal to the wave vector of the surface plasma wave, resonant coupling occurs for a properly chosen thickness of the film. Since, because the angle of incidence is beyond the critical angle, no wave propagates into the third medium (air), surface plasma waves are detected by noting the deep minimum in the internal reflectance. Fig. 1 shows diagramatically the arrangement of its apparatus.
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Shoji, Naruki, Hideharu Takahashi, and Hiroshige Kikura. "Development of Three-Dimensional Velocity Vector Profiler Using Ultrasonic Pulsed Doppler Method." In ASME 2022 Fluids Engineering Division Summer Meeting. American Society of Mechanical Engineers, 2022. http://dx.doi.org/10.1115/fedsm2022-87878.
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Abstract In March 2011, the severe accident of the Fukushima Daiichi (1F) nuclear power plant was happened by the earth quack and massive tsunami in Tohoku, Japan. And then, fuel debris was generated within the primary containment vessels (PCVs) of units 1, 2, and 3, respectively. Recently, the decommissioning of 1F is underway to remove the fuel debris, and the inside inspection with robots was conducted so far. Optical techniques have been applied for inspecting the PCVs, but information of the contaminated water leakage has been not unveiled due to non-clear water causing poor visibility of the camera. Therefore, non-optical techniques are required to unveil the leakage location, and we focused on the ultrasonic measurement technique. In this study, we have developed the ultrasonic velocity profiler (UVP) system for the investigation of leaking locations. The UVP is based on the pulsed Doppler method, and it can measure instantaneous velocity profile along an ultrasonic beam path. In the original UVP principle, it can measure only one-dimensional velocity measurement. Therefore, we extended the UVP to multi-dimensional measurement. To achieve this, a transducer array was used and an algorithm of three-dimensional (3-D) velocity vector reconstruction was developed. The 3-D vector measurement is realized by simultaneous receiving Doppler signal at each ultrasonic element. The measurement performance was evaluated by the rigid rotating flow measurement. In addition, we checked the validity of the system for leakage detection by measuring the simulated leakage flow.
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Balabina, Tat'yana, Mariya Karelina, and Aleksey Mamaev. "WHEEL ROLLING ON GROUND WITH LEAVING." In PROBLEMS OF APPLIED MECHANICS. Bryansk State Technical University, 2020. http://dx.doi.org/10.30987/conferencearticle_5fd1ed03cdc1d3.71977713.
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Wheeled vehicles belong to the most common type of transport and technological machines and are used in almost all sectors of the national economy: in urban and intrafactory transport, in construction, in the army, in agriculture, etc. Due to the fact that wheeled vehicles must correspond to the solution of the tasks that this or that industry poses for them, their structure and types are very diverse. Among them are wheeled vehicles designed to operate not only on roads with asphalt-concrete pavement, but also on deformable soil surfaces. These include, in particular, machines used in road construction, in municipal services - wheeled tractors, wheeled earth-moving machines, general transport vehicles used for the transportation of various types of bulk cargo, and specialized, designed to perform narrow target functions. The performance indicators of wheeled vehicles are largely determined by the interaction of their wheels with the supporting surface, which has led to the implementation of a large number of studies in this area. The rolling of a wheel on a rigid surface has been studied in sufficient detail and is presented in a large number of works. At the same time, issues related to wheel rolling on deformable soil have not been sufficiently worked out, there are many uncertainties and inaccuracies. This applies, in particular, to the case of wheel rolling on the ground with a pull, when the plane of rotation of the wheel is deflected by a certain angle from the vector of the wheel axis velocity, which leads to the appearance of an additional lateral force acting on the tire sidewall and the corresponding moment of resistance to turning. When a wheel with a pneumatic high-pressure tire rolls, the wheel rolls on the ground, almost without changing its cylindrical shape, i.e. practically without deformation. This greatly simplifies the calculations associated with the analysis of the operation of wheeled vehicles. In this article, when considering the rolling of a wheel with withdrawal on deformable soil, the dependences were used to determine the longitudinal and transverse tangential stresses in contact, obtained for the case of wheel rolling on a solid foundation; determined the lateral force acting on the tire sidewall, and the corresponding moment of resistance to turning.