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Artykuły w czasopismach na temat "EROSION COLLISION"
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Maindl, Thomas I., Rudolf Dvorak, Christoph Schäfer i Roland Speith. "Fragmentation of colliding planetesimals with water content". Proceedings of the International Astronomical Union 9, S310 (lipiec 2014): 138–41. http://dx.doi.org/10.1017/s1743921314008059.
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AbstractWe investigate the outcome of collisions of Ceres-sized planetesimals composed of a rocky core and a shell of water ice. These collisions are not only relevant for explaining the formation of planetary embryos in early planetary systems, but also provide insight into the formation of asteroid families and possible water transport via colliding small bodies. Earlier studies show characteristic collision velocities exceeding the bodies' mutual escape velocity which—along with the distribution of the impact angles—cover the collision outcome regimes ‘partial accretion’, ‘erosion’, and ‘hit-and-run’ leading to different expected fragmentation scenarios. Existing collision simulations use bodies composed of strengthless material; we study the distribution of fragments and their water contents considering the full elasto-plastic continuum mechanics equations also including brittle failure and fragmentation.
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Cheng, Jiarui, Yihua Dou, Ningsheng Zhang, Zhen Li i Zhiguo Wang. "A New Method for Predicting Erosion Damage of Suddenly Contracted Pipe Impacted by Particle Cluster via CFD-DEM". Materials 11, nr 10 (28.09.2018): 1858. http://dx.doi.org/10.3390/ma11101858.
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A numerical study on the erosion of particle clusters in an abrupt pipe was conducted by means of the combined computational fluid dynamics (CFD) and discrete element methods (DEM). Furthermore, a particle-wall extrusion model and a criterion for judging particle collision interference were developed to classify and calculate the erosion rate caused by different interparticle collision mechanisms in a cluster. Meanwhile, a full-scale pipe flow experiment was conducted to confirm the effect of a particle cluster on the erosion rate and to verify the calculated results. The reducing wall was made of super 13Cr stainless steel materials and the round ceramsite as an impact particle was 0.65 mm in diameter and 1850 kg/m3 in density. The results included an erosion depth, particle-wall contact parameters, and a velocity decay rate of colliding particles along the radial direction at the target surface. Subsequently, the effect of interparticle collision mechanisms on particle cluster erosion was discussed. The calculated results demonstrate that collision interference between particles during one cluster impact was more likely to appear on the surface with large particle impact angles. This collision process between the rebounded particles and the following particles not only consumed the kinetic energy but also changed the impact angle of the following particles.
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Minton, Timothy K., Jianming Zhang, Donna J. Garton i James W. Seale. "Collision-Assisted Erosion of Hydrocarbon Polymers in Atomic-Oxygen Environments". High Performance Polymers 12, nr 1 (marzec 2000): 27–42. http://dx.doi.org/10.1088/0954-0083/12/1/303.
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Molecular beam–surface scattering experiments have been used to study the mechanisms of material removal when a hydrocarbon polymer surface erodes in the highly oxidizing environment of low Earth orbit or in a simulated space environment on Earth. During steady-state oxidation, CO and CO2 are produced. Formation of these volatile species is believed to account for a significant fraction of the mass loss of a polymer that is under atomic-oxygen attack. The rate of production of CO and CO2 is dramatically enhanced when a continuously-oxidized polymer surface is bombarded with Ar atoms or N2 molecules possessing translational energies greater than 8 eV. The yield of volatile products from the surface appears to increase exponentially with the collision energy of the inert atoms or molecules. Collisions of energetic inert species may accelerate the erosion of polymers in some exposure environments (e.g. in low Earth orbit, where N2 may strike oxidized surfaces with collision energies greater than 8 eV, and in certain atomic-oxygen test facilities that subject oxidized surfaces to bombardment by O2 molecules with average translational energies of approximately 10 eV).
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Hsu, Chia-Jung, Shou-Yi Chang, Liang-Yu Chou i Su-Jien Lin. "Investigation on the arc erosion behavior of new silver matrix composites: Part II. Reinforced by short fibers". Journal of Materials Research 18, nr 4 (kwiecień 2003): 817–26. http://dx.doi.org/10.1557/jmr.2003.0112.
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An electroless plating and hot-pressing process was developed to fabricate silver matrix composites reinforced with uniformly distributed graphite and Saffil short fibers (Graphitesf and Saffilsf). The hardness of the composites increases as the content of short fibers increase. Static-gap, single-spark erosion and repeated-collision, multiple-arc erosion tests were used to investigate the arc erosion behavior of the composites. The composites exhibited better arc erosion resistance when the contents of short fibers were increased in a static-gap, single-spark erosion test. However, the weight loss of the composites after 10,000 times repeated-collision, multiple-arc erosion operation shows that the composites with low volume percents of short fibers have a good arc erosion resistance. The Saffilsf/Ag composites show a better arc erosion resistance than Graphitesf/Ag because of the greater strengthening effect of the finer Saffil short fibers. The erosion behavior of the composites is dominated by the viscosity of composites in single-spark tests, while it depends on the competition of viscosity and thermal properties in multiple-arc tests.
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Bai, Xupeng, Yongming Yao, Zhiwu Han, Junqiu Zhang i Shuaijun Zhang. "Study of Solid Particle Erosion on Helicopter Rotor Blades Surfaces". Applied Sciences 10, nr 3 (3.02.2020): 977. http://dx.doi.org/10.3390/app10030977.
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In this study, titanium alloy (Ti-4Al-1.5Mn), magnesium alloy (Mg-Li9-A3-Zn3), or aluminum alloy (Al7075-T6) were used to construct the shell model of helicopter rotor blade to study the solid particle erosion of helicopter rotor blades. The erosion resistance of the three materials at different angles of attack (6°, 3°, or 0°) and particle collision speeds (70, 150, or 220 m/s) was examined using the finite volume method, the discrete phase method, and erosion models. In addition, the leading edge of the helicopter blades was coated with two types of bionic anti-erosion coating layers (V- and VC-type), in an attempt to improve erosion resistance at the angles of attack and particle collision speeds given above. The results showed that Ti-4Al-1.5Mn had the best erosion resistance at high speed, followed by Al7075-T6 and Mg-Li9-A3-Zn3. The angle of attack appeared to affect only the surface area of the blade erosion, while the erosion rate was not affected. Finally, the results of this article showed that the V-type bionic coating had better erosion resistance than the VC-type coating at the same impact speeds. The angle of attack did not have a significant effect on the erosion rate of the bionic coating.
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Yokota, Kumiko, Masahito Tagawa, Yusuke Fujimoto, Wataru Ide, Yugo Kimoto, Yuta Tsuchiya, Aki Goto, Kazuki Yukumatsu, Eiji Miyazaki i Shunsuke Imamura. "Effect of simultaneous N2 collisions on atomic oxygen-induced polyimide erosion in sub-low Earth orbit: comparison of laboratory and SLATS data". CEAS Space Journal 13, nr 3 (7.04.2021): 389–97. http://dx.doi.org/10.1007/s12567-021-00358-4.
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AbstractThe role of N2 in the upper atmosphere on the atomic oxygen (AO)-induced erosion of polyimide in low Earth orbit (LEO) and sub-LEO is investigated through ground-based experiments and flight data. The experiment is performed by adding an Ar beam at the same collision energy as an undecomposed O2 component in the AO beam formed by laser detonation to simulate the physical effect of simultaneous N2 collision in sub-LEO. The Ar beam is added by the dual-pulsed supersonic valve-equipped laser-detonation system developed at Kobe University. The experimental results indicate that the erosion of polyimide in the laser-detonation system is promoted by the presence of O2 and Ar in the beam, corresponding to N2 in the sub-LEO. On-ground experimental results are compared with in-orbit AO measurements. Previous space shuttle, international space station-based exposure experiments, as well as the world’s first real-time sub-LEO material erosion data aboard a super low altitude test satellite (SLATS) orbiting at an altitude of 216.8 km are presented. The SLATS data suggests the presence of an acceleration effect by N2 collision on AO-induced polyimide erosion, as predicted by ground-based experiments.
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Han, Yigui, Guochun Zhao, Peter A. Cawood, Min Sun, Qian Liu i Jinlong Yao. "Plume-modified collision orogeny: The Tarim–western Tianshan example in Central Asia". Geology 47, nr 10 (30.08.2019): 1001–5. http://dx.doi.org/10.1130/g46855.1.
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Abstract Plume-modified orogeny involves the interaction between a mantle plume and subducting oceanic lithosphere at accretionary margins. We propose that a plume can also be involved in collisional orogeny and accounts for the late Paleozoic geological relations in Central Asia. Continental collision between the Tarim and Central Tianshan–Yili blocks at the end Carboniferous resulted in an orogeny lacking continental-type (ultra)high-pressure [(U)HP] rocks and significant syncollision surface erosion and uplift, features normally characteristic of continent-continent interactions. Their absence from the Tianshan region corresponded with the arrival of a mantle plume beneath the northern Tarim. Elemental and isotopic data reveal an increasing influence of the mantle plume on magmatic petrogenesis from ca. 300 to 280 Ma, immediately after collision at 310–300 Ma. The rising mantle plume interrupted the normal succession of collisional orogenic events, destroying the deeply subducted continental crust and hence preventing slab break-off–induced continental rebound. Plume-modified continental collision thus limited continental (U)HP rock exhumation and associated surface uplift.
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Dong, Yunshan, Zongliang Qiao, Fengqi Si, Bo Zhang, Cong Yu i Xiaoming Jiang. "A Novel Method for the Prediction of Erosion Evolution Process Based on Dynamic Mesh and Its Applications". Catalysts 8, nr 10 (30.09.2018): 432. http://dx.doi.org/10.3390/catal8100432.
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Particle erosion is a commonly occurring phenomenon, and it plays a significantly important role in service life. However, few simulations have replicated erosion, especially the detailed evolution process. To address this complex issue, a new method for establishing the solution of the erosion evolution process was developed. The approach is introduced with the erosion model and the dynamic mesh. The erosion model was applied to estimate the material removal of erosion, and the dynamic mesh technology was used to demonstrate the surface profile of erosion. Then, this method was applied to solve a typical case—the erosion surface deformation and the expiry period of an economizer bank in coal-fired power plants. The mathematical models were set up, including gas motion, particle motion, particle-wall collision, and erosion. Such models were solved by computational fluid dynamics (CFD) software (ANSYS FLUENT), which describes the evolution process of erosion based on the dynamic mesh. The results indicate that: (1) the prediction of the erosion profile calculated by the dynamic mesh is in good agreement with that on-site; (2) the global/local erosion loss and the maximum erosion depth is linearly related to the working time at the earlier stage, but the growth of the maximum erosion depth slows down gradually in the later stage; (3) the reason for slowing down is that the collision point trajectory moves along the increasing direction of the absolute value of θ as time increases; and (4) the expiry period is shortened as the ash diameter increases.
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Kimijima, Satomi, Masayuki Sakakibara, Abd Kadir Mubarak A. Amin, Masahiko Nagai i Yayu Indriati Arifin. "Mechanism of the Rapid Shrinkage of Limboto Lake in Gorontalo, Indonesia". Sustainability 12, nr 22 (18.11.2020): 9598. http://dx.doi.org/10.3390/su12229598.
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This study explores the mechanisms behind the rapid shrinkage of Limboto Lake, Gorontalo, Indonesia, using remotely sensed imagery and river outcrop investigation data. The results show that more than 70% of the sedimentation resulting in shrinkage is contributed by riverbank erosion causing rivers to drain into the lake during the period 2003–2017. From geological investigation, it is found that the lowland area to the west of Limboto Lake comprises 1 m of flood sediments, followed by at least 5 m of fine-grained inner bay sediments. Severe riverbank erosion is also observed at many points. Hence, it is concluded that the shrinkage of Limboto Lake resulted from rapid-induced rapid erosion of inner bay sediments formed during plate collision which readily flowed into and were deposited in Limboto Lake; this created a delta, especially on the west side of the lake. Accelerated sedimentation caused by river erosion has led to rapid lake shrinkage. This phenomenon could be typical of the transformation of enclosed seas into lakes by the rapid uplifting movement of land in collision zones.
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Matte, Philippe. "The Southern Urals: deep subduction, soft collision and weak erosion". Geological Society, London, Memoirs 32, nr 1 (2006): 421–26. http://dx.doi.org/10.1144/gsl.mem.2006.032.01.25.
Pełny tekst źródłaRozprawy doktorskie na temat "EROSION COLLISION"
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Hoth, Stefan. "Deformation, erosion and natural resources in continental collision zones insight from scaled sandbox simulations /". [S.l.] : [s.n.], 2005. http://www.diss.fu-berlin.de/2006/149/index.html.
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Hoth, Silvan. "Deformation, erosion and natural resources in continental collision zones insight from scaled sandbox simulations /". Potsdam : Geoforschungszentrum [u.a.], 2006. http://deposit.d-nb.de/cgi-bin/dokserv?idn=979803195.
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Piestrzeniewicz, Adam. "From terrane accretion to glacial erosion: Characterizing the evolution of the St. Elias orogen in southeast Alaska and southwest Yukon using low-temperature thermochronology". University of Cincinnati / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1439279821.
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Mesalles, Lucas. "Mountain building at a subduction-collision transition zone, Taiwan : insights from morphostructural analysis and thermochronological dating". Thesis, Paris 6, 2014. http://www.theses.fr/2014PA066676/document.
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Cette étude est focalisé sur le Sud de la Chaîne Centrale de Taïwan, située à la transition entre la subduction et la collision arc-continent. La déformation du Sud de l'île est caractérisée par deux domaines distincts structuralement: une unité à vergence Ouest définie autour des plus hauts sommets, et une unité à vergence Est observée dans les vallées de l'Est. Les unités sont bordées par de grandes zones de cisaillement inclinées vers l'Ouest qui indiquent une phase d'extension tardive réactivant des décrochements senestres plus anciens. Le résultat des datations par traces de fission (TF) sur zircon le long d'un profil vertical révèlent un début de refroidissement à 7.2 Ma un taux minimum de 21°C/Ma, suivi d'une accélération de l'exhumation d'un ordre de grandeur après 3.2 Ma et d'une augmentation du gradient géothermique de ~41°C/km à 65°C/km. Les TF sur zircon et apatite détritiques des sédiments syn-orogéniques Plio-Pléistocène de l'avant-pays occidental suggèrent l'exhumation de la couverture à l'Ouest de la chaîne caractérisée par des âges similaires à ceux trouvés dans l'intérieur de la chaîne. L'analyse géomorphologique au Sud de la Chaîne Centrale révèle l'existence de zones à faible relief à hautes altitudes, à l'aplomb de la ligne de partage des eaux actuelle et cœur métamorphique. Des considérations morphologiques et climatiques indiquent une origine probablement glaciaire pour ces surfaces. La coïncidence spatiale entre les surfaces de faibles reliefs et la position du cœur métamorphique suggère le rôle potentiel des glaciations lors de l'exhumation récente du cœur de la chaîne à Taïwan, et probablement dans d'autres chaines à basses latitudesThe present study focuses on the southern Taiwan Central Range, located at the transition between subduction and arc-continent collision. Field-work and structural analysis shows that deformation in the southern Central Range presents two major and distinct structural domains: a west-verging structural unit roughly limited to the western divide, and an east-verging unit, covering most of the eastern divide. The structural units are limited by a steeply west-dipping shear zones displaying a dominant late stage normal faulting and an early strike-slip faulting stage. Zircon fission track dating (FT) along a vertically sampled profile reveal onset of cooling at 7.2 Ma at a minimum rate of 21°C/m.y., followed by an order of magnitude acceleration of exhumation after ca. 3.2 Ma and increase of geothermal gradients from ~41°C/km to 65°C/km. Detrital zircon and apatite FT derived from Plio-Pleistocene sediments from the southwestern foreland basin display the erosion of the western divide cover rocks with ages similar to the early phase seen in the hinterland. Geomorphic analysis of the southern Central Range reveals the existence of low relief at high altitudes, located along the drainage divide and locally on top of the metamorphic core. Morphological and climatic considerations indicate the likely glacial origin of these surfaces. The spatial coincidence of the southernmost low-relief surfaces with the southernmost exposure of the metamorphic core at the main divide suggest a potential role of glaciations in the recent exhumation of the metamorphic core in Taiwan, and probably in other low-latitude orogens
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Collot, Jean-Yves. "Obduction et collision : exemples de la Nouvelle-Calédonie et de la zone de subduction des Nouvelles-Hébrides". Paris 11, 1989. http://www.theses.fr/1989PA112401.
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Deux cas particuliers d'évolution de la lithosphère océanique aux frontières de plaques sont examinés en utilisant les méthodes modernes de la géophysique marine. Le premier est celui de l'abduction d'une nappe ophiolitique sur un fragment continental en Nouvelle-Calédonie et le second celui de la déformation de la lithosphère de l'arc insulaire des Nouvelles-Hébrides en réponse à la collision d'aspérités topographiques portées par la plaque plongeante. La nappe ophiolitique de Nouvelle-Calédonie s'est mise en place tectoniquement à l'Eocène supérieur sur un substratum permien à éocène supérieur. Notre étude montre que cette ophiolite, épaisse au maximum de 10 km, résulte de l'obduction d'un fragment de lithosphère océanique du bassin des Loyauté adjacent à la Nouvelle-Calédonie. Cette abduction se serait accomplie sur environ 800 km, le long de la ride de Nouvelle-Calédonie, sans faire intervenir de collision continent-arc ou continent-continent. Nous discutons du contexte géodynamique de l'ophiolite au moment de sa rupture et de son abduction. La Zone d'Entrecasteaux (DEZ) et le Massif Ouest Torres sont deux aspérités topographiques sous-marines hautes de 1000 à 3000 rn qui entrent en collision et subductent sous l'arc insulaire des Nouvelles-Hébrides à 10 cm/an. La DEZ est légèrement oblique à la direction de convergence des plaques de telle façon qu'elle balaye l'arc vers le Nord à environ 2. 5 cm/an. L'analyse des structures de la plaque plongeante et de l'arc des Nouvelles-Hébrides centrales suggère que la déformation résultant d'une collision peut se développer dans des directions opposées. Dans le cas de la subduction/collision de la DEZ, la déformation se développe sur l'arc et affecte la marge qui s'épaissit et se soulève de 3 à 4 mm/an depuis le Pliocène terminal, le bassin intra-arc qui se fracture et subside et la zone arrière-arc qui se comprime et tend à chevaucher la bassin marginal adjacent. A l'opposé au sud de cette zone de collision, dans une région précédemment balayée par la DEZ, la déformation se développe vers l'océan depuis la marge qui s'effondre, jusque sur la plaque plongeante qui subit un raccourcissement. Bien que des indices d'accrétion sous la marge soient discutés, l'érosion tectonique de cette marge semble être un des phénomènes majeurs résultant de la collision et du balayage d'une aspérité topographique le long de l'arc.
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Hoth, Silvan [Verfasser]. "Deformation, erosion and natural resources in continental collision zones : insight from scaled sandbox simulations / Geoforschungszentrum Potsdam, Stiftung des Öffentlichen Rechts. Vorleget von Silvan Hoth". Potsdam : Geoforschungszentrum, 2006. http://d-nb.info/979803195/34.
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Lelarge, Maria Lidia Meideros Vignol. "Thermochronologie par la méthode des traces de fission d'une marge passive (dôme de Ponta Grossa, se Brésil) et au sein d'une chaîne de collision (zone externe de l'arc alpin, France)". Université Joseph Fourier (Grenoble), 1993. https://tel.archives-ouvertes.fr/tel-00603209.
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La méthode de datation par les traces de fission sur apatite a été appliquée dans deux contextes différents: une marge passive (dôme de Ponta Grossa dans l'état du Paraná au sud-est du Brésil) et une chaine de collision (massifs de Belledonne et du grand Châtelard, ainsi que la zone dauphinoise interne, dans les Alpes occidentales françaises). L'objectif de ce mémoire était de retracer l'histoire du refroidissement des roches de ces deux régions et dans une certaine mesure d'établir une chronologie des processus géodynamiques qui s'y sont produits. Les apatites du dôme de Ponta Grossa ont enregistré le refroidissement provoqué par la surrection-érosion de la serra do mar, chaïne montagneuse qui longe la côte sud-est brésilienne. La serra do mar correspond probablement a une réponse tardive à l'ouverture de l'Atlantique sud, qui s'est effectuée vers 120 MA aux environs de la latitude 26s. Les âges tracés de fission (tf) apparents des 21 échantillons analyses s'échelonnent entre 100 MA et 80 MA. L'analyse des résultats tf sur apatite, obtenus sur les 33 échantillons alpins, indique que l'histoire du refroidissement de cette région est extrêmement complexe. Les âges apparents tf sont compris entre 7,5 MA et 1,7 MA. Les taux de dénudation sont variables selon le secteur étudié et expriment ainsi un comportement différent vis-à-vis des processus tectoniques. Depuis le miocène supérieur jusqu'a 1 MA, les taux de dénudation apparents sont estimes a 0,4 mm/an pour le massif de Belledonne et à 0,7 mm/an pour le grand Châtelard et la zone du flysch. A partir d'un million d'années jusqu'à l'actuel le taux de dénudation apparent augmente et devient de l'ordre de 2 mm/an, pour l'ensemble de la région
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Studnicki-Gizbert, Christopher Terrance. "Deformation, erosion and sedimentation in collisional orogens : case studies from eastern Tibet and southwestern China". Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/38250.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 2006.Includes bibliographical references.
This dissertation addresses aspects of the tectonics of regions adjacent to the eastern Himalayan syntaxis. The first chapter describes the Tertiary Gonjo basin, includes structural and sedimentologic observations, and interprets these as a record of limited upper crustal shortening during and immediately after early Tertiary (- 40 Ma) time. The record of Cenozoic shortening of the upper crust cannot account for the gradient of crustal thicknesses from eastern Tibet southeast into Yunnan province. The second chapter provides a review of the regional geology of western Yunnan and the detailed structural geology of the region around the first bend of the Jinsha (Yangzi) river. Structures record a long history of multiple deformation generations, including early Mesozoic metamorphism and cooling, west-directed transport along thrusts and nappes in late Mesozoic time, limited Tertiary shortening and transtensional deformation from Pliocene to present time. The third chapter provides a synoptic view of the active tectonics around the eastern Himalayan syntaxis and integrates geologic mapping, slip-rate estimates, remote sensing, seismicity and geodesy. Fault slip rates are inferred by modeling the elastic deformation near major faults and the motions of a small number of crustal blocks.
(cont.) Elastic block modeling explains geodetic velocities but fails to capture many important aspects of the geologic record, especially poorly localized strain within and near the margins of the Lanping-Simao belt. The final chapter describes the Pliocene to present structural and geomorphic evolution of the Yulong mountains and the interactions of active upper-crustal transtensional deformation, weak lower or middle crust, and geomorphic processes (specifically river incision). The exposure of deep structural levels and high rock uplift rates of the Yulong mountains are explained as the result of erosion processes that balance rock uplift rates, a closed network of normal faults that accommodate differential rock uplift rates, and weak middle crust that flows in response to topographically imposed pressure gradients.
by Christopher Terrance Studnicki-Gizbert.
Ph.D.
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Chalaron, Edouard. "Modélisation numérique et signature géologique des interactions entre tectonique, érosion et sédimentation dans l'avant-pays himalayen". Phd thesis, Université de Grenoble, 1994. http://tel.archives-ouvertes.fr/tel-00723716.
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Les structures chevauchantes frontales d'une chaîne de collision et son bassin d'avant-pays constituent une zone où le déplacement des écailles chevauchantes, l'érosion, la sédimentation et la subsidence du substratum se produisent simultanément. Ces différents phénomènes interfèrent et conduisent à une évolution en régime permanent constituée d'une suite d'exhumations et d'enfouissements des écailles des structures. Des modèles originaux développés en Pascal pour chacun des phénomènes sont couplés dans un algorithme général. En faisant varier la valeur des paramètres géométriques et / ou mécaniques, il est ainsi possible d'étudier et de quantifier l'influence de ces phénomènes sur le développement et l'histoire tectonique des fronts de chaîne de collision. De plus ces modèles fournissent un aperçu des faciès sédimentaires à partir des pentes à l'instant du dépôt des sédiments dans les bassins. En effet, lors d'études expérimentales des systèmes fluviatiles, des faciès corrélés avec des classes de pentes ont été mises en évidence par certains auteurs. Dans une deuxième partie le modèle développé est appliqué à la chaîne des Siwalik, piémont de la chaîne himalayenne. Les Siwalik se comportent comme un prisme tectonique décollé à la base lors d'un raccourcissement imposé à l'arrière et érodé en surface. Classiquement on distingue trois formations dans cette chaîne: les Siwalik Inférieur, Moyen et Supérieur. Les premiers dépôts sont datés autour de 18 Ma. Depuis, les conditions de dépôt sont toujours continentales. Au Népal occidental les sédiments des Siwalik sont affectés de plis, de chevauchements et de structures rétrochevauchantes pouvant être séparés par des bassins intramontagneux (duns) déplacés au toit des écailles chevauchantes. L'analyse de la réflectance de la vitrinite (VR0) montre qu'une érosion intense contemporaine de l'activité tectonique équilibre l'épaississement tectonique et empêche ainsi un enfouissement important des séries sédimentaires. Le Main Boundary Thrust (MBT), montre une composante normale des mouvements récents sur une grande partie de sa longueur. Des données microstructurales échantillonnées le long d'un tronçon du MBT sont utilisées pour calibrer les paramètres mécaniques de la chaîne en la considérant comme un prisme de Coulomb. Ces paramètres sont utilisés dans le modèle numérique décrit précédemment afin de caractériser les séquences d'activation des failles dans le système chevauchant des Siwalik ainsi que la sédimentation syn-tectonique associée. La comparaison entre la distribution de la déformation dans l'avant-pays himalayen et dans le modèle numérique montre que le prisme himalayen est en régime permanent contrôlé par une convergence horizontale et par les phénomènes superficiels et se caractérise par une distribution spatiale et temporelle irrégulière des mouvements des failles dans l'ensemble du prisme. Un traitement par Modèle Numérique de Terrain est ensuite appliqué à deux zones de la chaîne des Siwalik au Népal occidental et permet de comparer les structures prédites avec celles proposées par l'analyse de ces MNT pour expliquer la localisation des virgations des structures et leur relation avec le plan de décollement sous-jacent. Finalement l'analyse de la sédimentation dans les bassins transportés et la comparaison des données au secteur de Nahan Dehra-Dun (Inde occidentale) permet d'apprécier le rôle joué par les paramètres dépendant du temps et permet de mieux cerner l'origine des fluctuations enregistrées dans les sédiments de la zone externe de la chaîne himalayenne. En termes de climatologie et de phénomènes superficiels les schémas d'évolutions proposés par les modèles numériques et appliqués à la chaîne himalayenne tendent à montrer qu'il existe une transition brutale vers -6,5 Ma. Les adaptations nécessaires au rééquilibrage par succession d'amincissements et d'épaississement crustaux de la chaîne himalayenne afin de conserver une évolution en régime permanent sont enregistrées dans les bassins sédimentaires périphériques proches ou distaux.
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Fontaine, Asmaa. "Etude des équilibres chimiques dans le contexte d'accrétion et de différenciation des planètes telluriques". Thesis, Clermont-Ferrand 2, 2014. http://www.theses.fr/2014CLF22457/document.
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Les abondances en éléments sidérophiles du manteau terrestre indiquent une ségrégation du noyau dans un océan magmatique profond. Il est néanmoins difficile de contraindre les conditions d’oxydation prévalant lors de l’accrétion planétaire, en se basant sur les traceurs géochimiques, en raison du nombre important de paramètres qui affectent leurs partages entre métal et silicate. D’autre part, l’état d’oxydation des planètes peut évoluer au cours de l’accrétion. Par conséquent, la nature des matériaux accrétés lors de la formation des planètes reste incertaine. Afin d’apporter de nouveaux éléments de réponses à cette problématique, nous avons modélisé les équilibres chimiques ayant lieu dans la Terre primitive. Ces équilibres peuvent évoluer (i) en augmentant les conditions de pression et de température de la ségrégation du noyau lors de la croissance de la planète, (ii) en raison de la cristallisation de l’océan magmatique et (iii) à travers l’accrétion de matériaux hétérogènes de compositions et états redox différents. Nous avons exploré le rôle potentiel de l’érosion collisionnelle dans le contexte de l’accrétion de la Terre à partir de chondrites à enstatite. Pour cela, nous avons déterminé expérimentalement les compositions chimiques des liquides pseudo-eutectiques en fonction de la pression jusqu’à 25 GPa. Nous avons montré que ces premiers liquides sont très enrichis en SiO2 (jusqu’à 75 wt% SiO2) et en éléments alcalins (Na et K). Par conséquent, l’érosion collisionnelle de proto-croutes de planétésimaux formés de chondrites EH peut de manière efficace augmenter le rapport final Mg/Si du manteau terrestre et réduire ses concentrations en éléments alcalins volatils. Ce mécanisme peut donc concilier les différences compositionnelles entre la Terre et les chondrites à enstatite. Nous avons également déterminé expérimentalement le partage du soufre entre métal riche en fer et silicate. La concentration en soufre du manteau terrestre peut être expliquée par un équilibre entre manteau et noyau dans un océan magmatique profond. L’hypothèse de l’ajout de soufre dans un vernis tardif (Rose-Weston et al., 2009) n’est pas à exclure, mais il n’est pas indispensable pour atteindre la concentration en soufre du manteau. Ces résultats sont en accord avec les compositions isotopiques non chondritiques du soufre dans le manteau (Labidi et al., 2013). Le partage des éléments légers (S, Si, O) entre manteau et noyau a été modélisé à hautes pressions et températures en prenant compte de leurs interactions chimiques mutuelles et celles avec le carbone. En considérant 2 wt% S et jusqu’à 1.2 wt% C (comme il est suggéré par les études cosmochimiques), nous trouvons une solubilité de l’O comprise entre 1 et 2.4 wt%. Cette insertion de l’O dans le noyau n’est pas suffisante pour permettre à la Terre d’être à la fois accrétée de matériaux météoritiques oxydés et de posséder un noyau métallique d’une masse équivalente au tiers de la planète ainsi que 8 wt% FeO dans le manteau. Des conditions relativement réduites lors de la ségrégation du noyau sont également requises pour augmenter le taux de Si dans le noyau et expliquer le rapport Mg/Si super-chondritique de la Terre silicatée (Allègre et al., 1995; O’Neill et al. 1998). Ainsi, la Terre s’est plus probablement accrétée à partir de matériaux réduits comme les chondrites à enstatites, conduisant à un noyau constitué de 2 wt% S, 0 à 1.2 wt% C, 1 wt% O et 5.5 à 7 wt% Si. Nous avons également exploré le comportement du Fe lors de la cristallisation de la pérovskite magnésienne (le minéral le plus abondant du manteau terrestre) et son rôle sur l’état redox du manteau terrestre lors du refroidissement de l’océan magmatique. Nous avons montré que sa cristallisation induit une diminution du FeO dans le manteau solide, lors d’un équilibre avec un alliage de fer liquide à une fO2 de IW-2 en raison du caractère incompatible du Fe dans la pérovskite. (...)Abundances of siderophile elements in the mantle indicate that the Earth’s core segregated in a deep magma ocean. Yet, it is unfortunately difficult to constrain the oxidation conditions prevailing during planetary accretion based on geochemical tracers due to the number of parameters playing a role in metalsilicate partitioning. In addition, the oxidation state of terrestrial planets can evolve during accretion. The nature of the accreted material during the formation of the terrestrial planets remains then still uncertain. Our strategy to improve our knowledge in this domain is to model the chemical equilibria taking place in the primitive Earth. The equilibria can evolve (i) as P-T conditions of core-mantle segregation increase with the size of the planet, (ii) due to crystallization of the magma ocean and (iii) with accretion of heterogeneous material of different composition and oxidation state. We explored the potential role of collisional erosion in the context of Earth’s accretion from Enstatite Chondrites. For this, we refined experimentally the chemical composition of pseudo-eutectic melts as a function of pressure up to 25 GPa. We show that the first melts are highly enriched in SiO2 (up to 75 wt% SiO2) and alkali elements (Na and K). Therefore, collisional erosion of proto-crusts on EH-planetesimals can efficiently increase their final Mg/Si ratio and decrease their alkali elements budget. It can help to reconcile compositional differences between bulk silicate Earth and Enstatite Chondrites. We performed new experiments on metal-silicate partitioning of sulphur. We show that the present-day sulphur concentration of the Earth’s mantle can be explained by core-mantle equilibration in a deep magma ocean. S-addition in a late veneer (Rose-Weston et al., 2009) cannot be excluded; however, it is not required in order to reach the S-mantel abundance. Our results are consistent with the non-chondritic S-isotopic nature of the mantle (Labidi et al., 2013). We modeled the core-mantle partitioning of the light elements (S, Si, O) at high pressures and temperatures, by taking into account of their mutual chemical interactions and that with C. With 2 wt% S in the core and a C concentration ranging 0 to 1.2 wt% (as evidenced with cosmochemical studies), we found the O solubility from 1 to 2.4 wt%. This O incorporation to the core is insufficient to both allow an Earth accretion from an oxidized meteoritic material and result in a planet composed of a core with a mass equivalent to the third of its mass and a mantle with 8 wt% FeO content. Reduced conditions during coremantle segregation are also required to enhance the Si content in the core, possibly up to 5 wt% Si, to explain the super chondritic Mg/Si of the bulk silicated Earth (Allègre et al., 1995; O’Neill et al. 1998). Altogether, we find that the Earth was most likely accreted from a reduced material, such as enstatite chondrites, leading to a core composed of 2 wt% S, 0 to 1.1 wt% C, 1 wt% O and 5.5 to 7 wt% Si. We investigated the role of Mg-perovskite (the most abundant mineral of the mantle) crystallization on the oxidation state of Earth’s mantle during cooling of the magma ocean. We show that its crystallization induces a decrease of FeO content of the solid mantle as Fe is incompatible in perovskite, when it is in equilibrium with a liquid Fe-alloy at an fO2 of IW-2. At these conditions, the Fe3+ insertion is also low and constant (Fe3+/ Fetot of 21 ±4 %). Hence, the Mg-Pv crystallization cannot be responsible for a substantial increase of the Earth’s mantle oxygen fugacity during core segregation. (...)
Książki na temat "EROSION COLLISION"
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Enos, Robert A. Changes in gravity anomalies during erosion and isostatic rebound of collisional mountain ranges. 1992.
Znajdź pełny tekst źródłaCzęści książek na temat "EROSION COLLISION"
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Saito, Seiki, Masayuki Tokitani i Hiroaki Nakamura. "Progress of Binary-Collision-Approximation-Based Simulation for Surface Erosion by Plasma Irradiation". W Communications in Computer and Information Science, 176–86. Berlin, Heidelberg: Springer Berlin Heidelberg, 2014. http://dx.doi.org/10.1007/978-3-662-45289-9_16.
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Grove, M., G. E. Bebout, C. E. Jacobson, A. P. Barth, D. L. Kimbrough, R. L. King, Haibo Zou, O. M. Lovera, B. J. Mahoney i G. E. Gehrels. "The Catalina Schist: Evidence for middle Cretaceous subduction erosion of southwestern North America". W Special Paper 436: Formation and Applications of the Sedimentary Record in Arc Collision Zones, 335–61. Geological Society of America, 2008. http://dx.doi.org/10.1130/2008.2436(15).
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Zalasiewicz, Jan. "The oil window". W The Planet in a Pebble. Oxford University Press, 2010. http://dx.doi.org/10.1093/oso/9780199569700.003.0016.
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It is a few million years later—perhaps three, perhaps five. Sediment has been pouring onto a Silurian sea floor that will, much later, be sliced into by a different sea and become the rugged cliff-fringed coastline of central Wales. It has been pouring in so thick and fast that our pebble stuff is now some two kilometres or more down below that sea floor. This is quite rapid burial, even by geological standards, and one can blame changing geography for that. To produce a lot of sediment, there is need for a lot of erosion, and also for the production of something that can be eroded—that is, uplands and mountains on land. On Earth, such production of topography is supplied by the marvellous machine of plate tectonics. And at that time, the ocean between Avalonia and Scotland, that we call the Iapetus Ocean, had just about closed, and those two landmasses were just beginning to nudge into each other. Soft collision, it’s called, when the pressure from the adjoining continents is just enough for sections of crust to begin to be pushed up and (to compensate) pushed down in different places—but not enough for the wholesale crumpling that goes with the creation of great mountain ranges. Thus, the landmass that was then in, and just south of, what is today South Wales was driven upwards, while the floor of the sea that then covered Wales was forced downwards. The resultant flood of sediment was Nature’s means of trying to restore equilibrium. Here, the particular pattern of squashing of the pebble stuff is linked with those enormous, mysterious movements of continents hundreds and thousands of kilometres away. And mysterious they certainly were, for on the heels of the soft collision should have followed the hard collision and mountain-building. But it didn’t. The mountain-building did take place—but only eventually, and not until many millions of years later. The Welsh mountains are quite a bit younger than they should be—and so that story will have to wait. Another story developed in splendid isolation from such tectonic violence. We can showcase it now.
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Kimura, Gaku, Yujin Kitamura, Asuka Yamaguchi i Hugues Raimbourg. "Links among mountain building, surface erosion, and growth of an accretionary prism in a subduction zone—An example from southwest Japan". W Special Paper 436: Formation and Applications of the Sedimentary Record in Arc Collision Zones, 391–403. Geological Society of America, 2008. http://dx.doi.org/10.1130/2008.2436(17).
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Clift, P. D., U. Bednarz, R. Bøe, R. G. Rothwell, R. A. Hodkinson, J. K. Ledbetter, C. E. Pratt i S. Soakai. "Sedimentation on the Tonga Forearc Related to Arc Rifting, Subduction Erosion, and Ridge Collision: A Synthesis of Results from Sites 840 and 841". W Proceedings of the Ocean Drilling Program, 135 Scientific Results. Ocean Drilling Program, 1994. http://dx.doi.org/10.2973/odp.proc.sr.135.164.1994.
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Mohammadiha, Homayoon. "A View to Anorthosites". W Volcanology [Working Title]. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.97787.
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It seems anorthosites are by far interested by geologists because they give us great information about Earth history and how it was evolved in planetary geology. Planetary geology is subject the geology of the celestial bodies such as the planets and their moons, asteroids, comets, and meteorites. It is nearly abundant in the moon. So, it seems studying of these rocks give us good information about planetary evolution and the own early time conditions. Anorthosites can be divided into few types on earth such as: Archean-age (between 4,000 to 2,500 million years ago) anorthosites, Proterozoic (2.5 billion years ago) anorthosite (also known as massif or massif-type anorthosite) – the most abundant type of anorthosite on Earth, Anorthosite xenoliths in other rocks (often granites, kimberlites, or basalts). Furthermore, Lunar anorthosites constitute the light-colored areas of the Moon’s surface and have been the subject of much research. According to the Giant-impact hypothesis the moon and earth were both originated from ejecta of a collision between the proto-Earth and a Mars-sized planetesimal, approximately 4.5 billion years ago. The geology of the Moon (lunar science) is different from Earth. The Moon has a lower gravity and it got cooled faster due to its small size. Also, it has no plate tectonics and due to lack of a true atmosphere it has no erosion and weathering alike the earth. However, Eric A.K. Middlemost believed the astrogeology will help petrologist to make better petrogenic models to understand the magma changing process despite some terms geological differences among the Earth and other extraterrestrial bodies like the Moon. So, it seems that these future studies will clarify new facts about planet formation in planetary and earth, too.
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Demoulin, Alain. "Tectonic Evolution, Geology, and Geomorphology". W The Physical Geography of Western Europe. Oxford University Press, 2005. http://dx.doi.org/10.1093/oso/9780199277759.003.0010.
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The present-day major relief features of western Europe are to a great extent determined by the underlying geological structures, either passively or actively. To get a comprehensive picture of their morphological evolution and interrelations, this chapter provides an overview of the spatial and temporal characteristics of the larg-escale tectonic framework of the continent. After having described the west European landscape at the end of the Palaeozoic, to which time the oldest preserved landforms date back, an outline of the Mesozoic and Cenozoic history of the major tectonic domains follows. Finally, some denudation estimates highlighting the relationship between tectonics, erosion, and the resulting relief, will be discussed. The three main influences on the present-day topographic patterns are those of the Alpine orogeny, the Cenozoic West European rifting, and the imprint of Variscan structures. They combine within a regional stress field determined by the Africa–Eurasia collision and the Alpine push as well as the mid-Atlantic ridge push. Since the end of the Miocene, this stress field is characterized by a fan-shaped distribution of SHmax along the northern border of the Alpine arc. This gives way to a more consistent NW–SE to NNW–SSE direction of compression further from the chain (Bergerat 1987; Müller et al. 1992). Topographically, western Europe may be roughly divided into a series of belts parallel to the Alpine chain. The Alpine chain culminates in a number of peaks exceeding 4,000 m in elevation (4,810 m at Mont Blanc) but the average altitude is in the order of 2,000 m. To the north, the mountainous Alps are bordered by the Molasse foredeep basin whose surface makes an inclined plane descending northwards from c.1,000 m to c.300 m near the Donau River in the Regensburg-Passau area. To the north-west, the Molasse basin narrows between the Alps and the Jura Mountains and is occupied by several extended lakes inherited from Quaternary glacial activity. Next to the Molasse basin in the north and west is a wide belt of recently more or less uplifted areas between 200 and 1,000 m in elevation (and locally in excess of 1,000 m in the French Massif Central and the Bohemian massif).
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Orme, Antony R. "The Tectonic Framework of South America". W The Physical Geography of South America. Oxford University Press, 2007. http://dx.doi.org/10.1093/oso/9780195313413.003.0008.
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Tectonism is the science of Earth movements and the rocks and structures involved therein. These movements build the structural framework that supports the stage on which surface processes, plants, animals and, most recently, people pursue their various roles under an atmospheric canopy. An appreciation of this tectonic framework is thus a desirable starting point for understanding the physical geography of South America, from its roots in the distant past through the many and varied changes that have shaped the landscapes visible today. Tectonic science recognizes that Earth’s lithosphere comprises rocks of varying density that mobilize as relatively rigid plates, some continental in origin, some oceanic, and some, like the South American plate, amalgams of both continental and oceanic rocks. These plates shift in response to deep-seated forces, such as convection in the upper mantle, and crustal forces involving push and pull mechanics between plates. Crustal motions, augmented by magmatism, erosion, and deposition, in turn generate complex three-dimensional patterns. Although plate architecture has changed over geologic time, Earth’s lithosphere is presently organized into seven major plates, including the South American plate, and numerous smaller plates and slivers. The crustal mobility implicit in plate tectonics often focuses more attention on plate margins than on plate interiors. In this respect, it is usual to distinguish between passive margins, where plates are rifting and diverging, and active margins, where plates are either converging or shearing laterally alongside one another. At passive or divergent margins, such as the present eastern margin of the South American plate, severe crustal deformation is rare but crustal flexuring (epeirogeny), faulting, and volcanism occur as plates shift away from spreading centers, such as the Mid-Atlantic Ridge, where new crust is forming. Despite this lack of severe postrift deformation, however, passive margins commonly involve the separation of highly deformed rocks and structures that were involved in the earlier assembly of continental plates, as shown by similar structural legacies in the facing continental margins of eastern South America and western Africa. At active convergent margins, mountain building (orogeny) commonly results from subduction of oceanic plates, collision of continental plates, or accretion of displaced terranes.
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Singh, Sukhmander, Bhavna Vidhani i Ashish Tyagi. "Numerical Investigations of Electromagnetic Oscillations and Turbulences in Hall Thrusters Using Two Fluid Approach". W Plasma Science and Technology [Working Title]. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.99883.
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The first part of the contributed chapter discuss the overview of electric propulsion technology and its requirement in different space missions. The technical terms specific impulse and thrust are explained with their relation to exhaust velocity. The shortcoming of the Hall thrusters and its erosion problems of the channel walls are also conveyed. The second part of the chapter discuss the various waves and electromagnetic instabilities propagating in a Hall thruster magnetized plasma. The dispersion relation for the azimuthal growing waves is derived analytically with the help of magnetohydrodynamics theory. It is depicted that the growth rate of the instability increases with magnetic field, electron drift velocity and collisional frequency, whereas it is decreases with the initial drift of the ions.
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Hsieh, Meng-Long, i Peter L. K. Knuepfer. "Synchroneity and morphology of Holocene river terraces in the southern Western Foothills, Taiwan: A guide to interpreting and correlating erosional river terraces across growing anticlines". W Geology and geophysics of an arc-continent collision, Taiwan. Geological Society of America, 2002. http://dx.doi.org/10.1130/0-8137-2358-2.55.
Pełny tekst źródłaStreszczenia konferencji na temat "EROSION COLLISION"
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Martins, Diego, Francisco Souza i Ricardo Salvo. "NUMERICAL ANALYSIS OF EROSION IN CYCLONES CONSIDERING INTER-PARTICLE COLLISION". W 12th Spring School on Transition and Turbulence. ABCM, 2020. http://dx.doi.org/10.26678/abcm.eptt2020.ept20-0028.
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Agrawal, Madhusuden, Ahmadreza Haghnegahdar i Rahul Bharadwaj. "Improved Prediction of Sand Erosion by Accurate Particle Shape Representation in CFD-DEM Modelling". W SPE Annual Technical Conference and Exhibition. SPE, 2021. http://dx.doi.org/10.2118/206122-ms.
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Abstract Predicting accurate erosion rate due to sand particles in oil and gas production is important for maintaining safe and reliable operations while maximizing output efficiency. Computational Fluid Dynamic (CFD) is a powerful tool for erosion prediction as it provides detailed erosion pattern in complex geometry. In an effort to improve accuracy of erosion prediction, this paper proposes an algorithm to accurately represent particle shape in CFD erosion simulation through coupling with Discrete Element Method (DEM) for non-spherical shape particles. The fluid motions are predicted by CFD and the particle movements (including particle-particle and particle-wall collisions) and fluid-particle interaction are calculated using DEM. It is widely known that sand particles are of finite volume with a non-spherical shape, accurate representation of sand particles is important in CFD modelling for accurate prediction of erosion rate. Traditional CFD approach usages lagrangian tracking of sand particles through Discrete Phase Model (DPM), where a particle is assumed as a point mass for the calculation of trajectory and particle-wall interaction. Particle impact velocity and impact angle are important parameter in determining erosion. Assumption of point mass in DPM approach, will not capture particle-wall interaction accurately especially when particles are of non-spherical in shape. In additional, DPM approach ignores particle-particle interactions. This can adversary affect the accuracy of erosion predictions. Integrating non-spherical DEM collision algorithm with CFD erosion simulation, will overcome these limitations and improve erosion predictions. Benefits of this CFD-DEM erosion modelling was demonstrated for gas-solid flow in a 2" pipework which consists of out-of-plane elbows in series and blind-tees. Experimental dataset [1] for erosion pattern on each elbow was used to validate CFD predictions. Three different erosion CFD simulations were performed, traditional DPM based CFD simulation, CFD-DEM simulation for spherical shape particles and CFD-DEM simulation for non-spherical shape particles. CFD-DEM coupled simulations clearly show an improvement on erosion predictions compared to DPM based CFD simulation. Effect of non-spherical shape on rebound angle during particle-wall collision is captured accurately in CFD-DEM simulation. CFD-DEM simulation using non-spherical particle, was able to predict erosion pattern closer to experimental observations. This paper will demonstrate an increase in accuracy of sand erosion prediction by integrating DEM collision algorithm in CFD modelling. The prediction results of elbow erosion subject to a condition of dilute gas-particle flow are validated against experimental data. Improved prediction of erosion risk will increase the safety and reliability of oil & gas operations, while maximizing output efficiency.
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Hussainova, Irina, i Klaus-Peter Schade. "Applications of Impact Dynamics to Assessment of Composite Erosion Resistance". W World Tribology Congress III. ASMEDC, 2005. http://dx.doi.org/10.1115/wtc2005-63184.
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Surface damage or material removal during particle target collision is the result of material response to the contact stresses. Energy dissipation under two bodies collision may be estimated by means of the coefficient of velocity restitution and friction. Approach of impact dynamic and experimental study of dynamic coefficients has been applied to clarify the composite material behaviour under conditions of solid particle erosion. It has been shown that the level of energy dissipation during application and value of dynamic coefficient of friction can be a good guide for material selection for the use in conditions of dynamic loading.
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Luo, K., J. R. Fan i K. F. Cen. "DNS of Particle Dispersion and Material Erosion in Gas-Solid Two-Phase Circular Cylinder Wakes". W ASME 2006 2nd Joint U.S.-European Fluids Engineering Summer Meeting Collocated With the 14th International Conference on Nuclear Engineering. ASMEDC, 2006. http://dx.doi.org/10.1115/fedsm2006-98168.
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Particle dispersion and the resulting material erosion in a three-dimensional wake of circular cylinder were investigated by using direct numerical simulation (DNS). The domain decomposition method with patched grid and the high-order finite difference schemes were used to solve the flow. A new Lagrangian tracking solver was developed to trace the trajectories of particles in the non-uniform and unstructured grid. It is observed that particles at the smaller Stokes numbers can follow the vortex motion and have a relatively uniform distribution in the flow field. They usually collide with the downstream surface of the cylinder. The particles at the larger Stokes numbers tend to maintain their own motion and the particle-cylinder collision occurs in the upstream surface of the cylinder. But particles at the intermediate Stokes number of 1 are observed to assemble in the outer boundaries of the vortex structures and the thin band regions which connect two adjacent eddies. Due to the particular response characteristics, neither can these particles collide with the upstream surface, nor can they collide with the downstream surface of the cylinder. The increase of particle diameter leads to an exponential increase of the collision frequency and the material erosion. The local collision frequency is higher for each kind of particles when the inclination angle approximates zero. But the maximum local erosion happens when the inclination angle is between 30 degree and 60 degree. The larger the particle diameter is, the larger the inclination angle where the maximum erosion happens is. In addition, it is confirmed that the highest erosion ratio occurs when the collision angle between particles and cylinder is around 25 degree for the plastic material.
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Miranda, Cairen J., i John Palmore. "Predicting Erosion from Airborne Particles on Surfaces using a Soft-Sphere Collision Model". W AIAA AVIATION 2021 FORUM. Reston, Virginia: American Institute of Aeronautics and Astronautics, 2021. http://dx.doi.org/10.2514/6.2021-2636.
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Miranda, Cairen J., i John Palmore. "Withdrawal: Predicting Erosion from Airborne Particles on Surfaces using a Soft-Sphere Collision Model". W AIAA AVIATION 2021 FORUM. Reston, Virginia: American Institute of Aeronautics and Astronautics, 2021. http://dx.doi.org/10.2514/6.2021-2636.c1.
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Suzuki, Masaya, Kazuyuki Toda i Makoto Yamamoto. "Numerical Investigation on Wavy Streak Formation Due to Sand Erosion". W ASME 2005 Fluids Engineering Division Summer Meeting. ASMEDC, 2005. http://dx.doi.org/10.1115/fedsm2005-77074.
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It is well known that sand erosion is a typical multi-physic problem, that is, the interactions among flow field, particle motions and wall deformation are important. To simulate this phenomenon, turbulent flow field, particle trajectories and amount of erosion on an eroded wall are calculated repeatedly. In the computations of the flow field, compressible Navier-Stokes equations and low-Reynolds-number type k-ε turbulence model are adopted. Assuming that the concentration of suspended particles is dilute, particle-particle collision and the influence of particle motions on the flow field are neglected. The Neilson-Gilchrist erosion model is used to estimate the weight loss due to erosion. Based on this numerical procedure, the gas-particle two-phase turbulent flow field in 90-degree bend with a square cross-section is simulated, in order to clarify erosion pattern formation by fluid/particle/wall interaction.
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Morita, Ryo, Fumio Inada i Kimitoshi Yoneda. "Development of Evaluation System for Liquid Droplet Impingement Erosion (LDI)". W ASME 2009 Pressure Vessels and Piping Conference. ASMEDC, 2009. http://dx.doi.org/10.1115/pvp2009-77557.
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An evaluation system for liquid droplet impingement erosion (LDI) has been developed to predict the LDI location and the wall thinning rate. The results from previous studies and knowledge are organized and the LDI evaluation system that involves the “1. Flow Evaluation Step” and “2. LDI Evaluation Step” is suggested. The flow evaluation step includes the mass flow rate evaluation, flow distribution evaluation and droplet behavior evaluation. The LDI evaluation is conducted with LDI sensitivity function. The LDI sensitivity was test-evaluated in the steam piping model. The results show that the 1st and last elbows have higher LDI sensitivity because of the velocity condition. We also found that the droplet collision frequency is important when evaluating the LDI sensitivity.
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Fang, Zhou, Weiwei Hu, Deyu Liu i Guanghai Li. "Study on Numerical Simulation of Gas-Solid Erosion for Feed Type Tee". W ASME 2017 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/pvp2017-65092.
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A series of numerical simulation about gas-solid erosion for feed type tee have been taken out. The gas-solid two phase flow was formed in the tee with the solid particles coming from the top of the tee pipes and air blowing from the left side. Tee pipes erosion situation was simulated by DPM model in Fluent software. The serious erosion location in the tee pipes was analyzed with different speeds of solid and air. The reasonable distribution method of the particle velocity and gas velocity was put forward and the particles were remained in the intermediate position of the pipes. So the collision with the wall was reduced, and the pipeline erosion rate was slowed down, in addition, the service life of pipes was prolonged.
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Junichi, Kuki, Kazuyuki Toda i Makoto Yamamoto. "Development of Numerical Code to Predict Three-Dimensional Sand Erosion Phenomena". W ASME/JSME 2003 4th Joint Fluids Summer Engineering Conference. ASMEDC, 2003. http://dx.doi.org/10.1115/fedsm2003-45017.
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This paper presents a numerical procedure to predict a three-dimensional sand erosion phenomenon and the interaction between the flow field and the eroded surface. To simulate this phenomenon, the turbulent flow field, the particle trajectory and the amount of erosion on the eroded wall are calculated repeatedly. In computations of the flow field, compressible Navier-Stokes equations and low-Reynolds-number type k–ε turbulence model are adopted. Assuming that the concentration of suspended particle is dilute, particle-particle collision and the influence of particle motions on the flow field are neglected. The Neilson-Gilchrist erosion model is used to estimate the weight loss due to erosion. To verify the developed code, two types of 90-degree bends are computed. The results show that the present procedure can reasonably reproduce the sand erosion process and the temporal change of both the flow field and the wall surface qualitatively.
Raporty organizacyjne na temat "EROSION COLLISION"
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Bryant, Duncan, Mary Bryant, Jeremy Sharp, Gary Bell i Christine Moore. The Response of Vegetated Dunes to Wave Attack. Engineer Research and Development Center (U.S.), sierpień 2021. http://dx.doi.org/10.21079/11681/41580.
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Vegetation is believed to increase the stability of dunes during wave attack, but limited data is available. A physical model study was performed to evaluate changes in the dune stability with and without biomass, both above and belowground. The above and belowground biomass was modeled using wooden dowels and coir fibers, respectively. For both the collision and overwash storm impact regimes, the results of this study clearly demonstrate that the inclusion of biomass in the model dune reduces the erosion and overwash. The combination of both above and belowground biomass was the most effective at reducing erosion followed by belowground biomass, with aboveground biomass providing the smallest benefit regardless of the wave condition and water level. Additionally, the overwash of sediment and water was decreased with the inclusion of biomass, following the same trends as the erosion. As the dune eroded, the storm impact regime transitioned from collision to overwash. The inclusion of biomass delays this transition in storm impact regime, providing greater protection to coastal communities. This study highlights the need to consider dune vegetation for dune construction and coastal planning.
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Karlstrom, Karl, Laura Crossey, Allyson Matthis i Carl Bowman. Telling time at Grand Canyon National Park: 2020 update. National Park Service, kwiecień 2021. http://dx.doi.org/10.36967/nrr-2285173.
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Grand Canyon National Park is all about time and timescales. Time is the currency of our daily life, of history, and of biological evolution. Grand Canyon’s beauty has inspired explorers, artists, and poets. Behind it all, Grand Canyon’s geology and sense of timelessness are among its most prominent and important resources. Grand Canyon has an exceptionally complete and well-exposed rock record of Earth’s history. It is an ideal place to gain a sense of geologic (or deep) time. A visit to the South or North rims, a hike into the canyon of any length, or a trip through the 277-mile (446-km) length of Grand Canyon are awe-inspiring experiences for many reasons, and they often motivate us to look deeper to understand how our human timescales of hundreds and thousands of years overlap with Earth’s many timescales reaching back millions and billions of years. This report summarizes how geologists tell time at Grand Canyon, and the resultant “best” numeric ages for the canyon’s strata based on recent scientific research. By best, we mean the most accurate and precise ages available, given the dating techniques used, geologic constraints, the availability of datable material, and the fossil record of Grand Canyon rock units. This paper updates a previously-published compilation of best numeric ages (Mathis and Bowman 2005a; 2005b; 2007) to incorporate recent revisions in the canyon’s stratigraphic nomenclature and additional numeric age determinations published in the scientific literature. From bottom to top, Grand Canyon’s rocks can be ordered into three “sets” (or primary packages), each with an overarching story. The Vishnu Basement Rocks were once tens of miles deep as North America’s crust formed via collisions of volcanic island chains with the pre-existing continent between 1,840 and 1,375 million years ago. The Grand Canyon Supergroup contains evidence for early single-celled life and represents basins that record the assembly and breakup of an early supercontinent between 729 and 1,255 million years ago. The Layered Paleozoic Rocks encode stories, layer by layer, of dramatic geologic changes and the evolution of animal life during the Paleozoic Era (period of ancient life) between 270 and 530 million years ago. In addition to characterizing the ages and geology of the three sets of rocks, we provide numeric ages for all the groups and formations within each set. Nine tables list the best ages along with information on each unit’s tectonic or depositional environment, and specific information explaining why revisions were made to previously published numeric ages. Photographs, line drawings, and diagrams of the different rock formations are included, as well as an extensive glossary of geologic terms to help define important scientific concepts. The three sets of rocks are separated by rock contacts called unconformities formed during long periods of erosion. This report unravels the Great Unconformity, named by John Wesley Powell 150 years ago, and shows that it is made up of several distinct erosion surfaces. The Great Nonconformity is between the Vishnu Basement Rocks and the Grand Canyon Supergroup. The Great Angular Unconformity is between the Grand Canyon Supergroup and the Layered Paleozoic Rocks. Powell’s term, the Great Unconformity, is used for contacts where the Vishnu Basement Rocks are directly overlain by the Layered Paleozoic Rocks. The time missing at these and other unconformities within the sets is also summarized in this paper—a topic that can be as interesting as the time recorded. Our goal is to provide a single up-to-date reference that summarizes the main facets of when the rocks exposed in the canyon’s walls were formed and their geologic history. This authoritative and readable summary of the age of Grand Canyon rocks will hopefully be helpful to National Park Service staff including resource managers and park interpreters at many levels of geologic understandings...