Artykuły w czasopismach: „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.

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Sheikh Mamoo, Mohammad, Ataallah Soltani Goharrizi i Bahador Abolpour. "CFD SIMULATION OF EROSION BY PARTICLE COLLISION IN U-BEND AND HELICAL TYPE PIPES". Journal of the Serbian Society for Computational Mechanics 14, nr 2 (30.12.2020): 1–13. http://dx.doi.org/10.24874/jsscm.2020.14.02.01.

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Erosion caused by solid particles in curve pipes is one of the major concerns in the oil and gas industries. Small solid particles flow with a carrier liquid fluid and impact the inner wall of the piping, valves, and other equipment. These components face a high risk of solid particle erosion due to the constant collision, which may result in equipment malfunctioning and even failure. In this study, the two-way coupled Eulerian-Lagrangian method with the Oka erosion and Grant and Tabakoff particle-wall rebound models approach is employed to simulate the liquid-solid flow in U-bend and helical pipes using computational fluid dynamics. The effects of operating parameters (inlet fluid velocity and temperature, particle density and diameter, and mass flow rate) and design parameters (mean curvature radius/pipe diameter ratio) are investigated on the erosion of these tubes walls. It is obtained that increasing the fluid velocity and temperature, particle mass flow and particle density increase the penetration rate, particle diameter affects the rate of penetration, and increasing mean curvature radius/pipe diameter ratio decreases the rate of penetration.

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Votavová, Helena, i Michal Pohanka. "Study of Water Jet Collision of High Pressure Flat Jet Nozzles for Hydraulic Descaling". Applied Mechanics and Materials 821 (styczeń 2016): 152–58. http://dx.doi.org/10.4028/www.scientific.net/amm.821.152.

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One of the most effective methods for descaling hot-rolled steel products is performed using highpressure flat jet nozzles. These descaling nozzles are arranged in rows in hot rolling mills and areset in such a way that each adjoining pair of nozzles creates an overlapping area of water jet streams.Good homogeneity of the pressure distribution over the width of the hot-rolled plate is often used as anindicator of quality of the homogeneity of descaling. The presented laboratory measurements examineone pair of adjoining nozzles with a particular focus on the pressure distribution in the overlappingarea. This paper deals with one particular setting of a pair of descaling nozzles with zero offset anglesfor the jet streams. A measured pressure distribution and an outcome of an erosion test on an aluminumplate are presented and discussed. The erosion test shows that spots with higher pressures do notnecessarily result in a higher amount of removed material during an erosion test. The erosion test differs from the expected outcome in such a way that a detailed discussion of this phenomenon is outlined with possible explanations.

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Shanmugam, Suresh Kumar, Thirumalai Kumaran Sundaresan, Temel Varol i Rendi Kurniawan. "Solid Particle Erosion Studies of Varying Tow-Scale Carbon Fibre-Reinforced Polymer Composites". Materials 15, nr 21 (27.10.2022): 7534. http://dx.doi.org/10.3390/ma15217534.

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Solid particle erosion inevitably occurs if a gas–solid or liquid–solid mixture is in contact with a surface, e.g., in pneumatic conveyors. Nowadays, an erosive failure of the component after the usage of a long period has been gaining the interest of the researchers. In this research work, carbon fibre-reinforced polymer (CFRP) composites are prepared by varying the tow sizes of fibres, such as 5k, 10k, and 15k. The prepared composites are subjected to erosion studies by varying the process parameters, such as the impact angle (30, 60, and 90 degrees) and velocity (72, 100, and 129 m/s). The Taguchi orthogonal array design has been employed for the experimental plan and the erosion rate and surface roughness are observed for each run. The changes in the responses are reported for varying process parameters. The higher erodent velocity of 129m/s leads to higher erosion rates and forms poor surface quality. The minimum impact angle of 30 degrees provides higher erosion rates and higher surface roughness than the other impingement angles. Finally, the eroded surface of each sample is examined through microscopic and 3D profilometer images and the erosion mechanism is analysed at different conditions. The eroded particles supplied at lower speeds do not penetrate the composite surface. However, it is well-known that the lower the collision force, the harder the traces on the surface, yet no sign of fibre breaking or pull-out is observed. The passage of erodent particles on the composite caused surface waviness (flow trace), which prevents the surface from degrading.

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Koronovskiy, N. V., G. V. Bryantseva, A. D. Zhigalin, E. V. Arkhipova i O. V. Anisimova. "The latest structures and seismicity of Zagros". Moscow University Bulletin. Series 4. Geology, nr 5 (16.12.2022): 9–18. http://dx.doi.org/10.33623/0579-9406-2022-5-9-18.

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The modern structure of the Zagros folding-thrust structure was formed under the influence of collision processes on the eastern flank of the collision zone of Eurasia and Arabia. Based on structural-geomorphological analysis and spatio-temporal features of the seismicity distribution, the article considers the features of the latest and modern geodynamic development of Zagros as a classical collision orogen. It is noted that the orogen is at the stage of erosion development, its seismic activation is associated to a greater extent with local deformations within individual blocks and is transformed under the influence of intense man-made impacts associated with the extraction of hydrocarbons within the Mesopotamian Lowland and the Persian Gulf.

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Garzanti, Eduardo, Giovanni Vezzoli, Sergio Andò, Christian France-Lanord, Sunil K. Singh i Gavin Foster. "Sand petrology and focused erosion in collision orogens: the Brahmaputra case". Earth and Planetary Science Letters 220, nr 1-2 (marzec 2004): 157–74. http://dx.doi.org/10.1016/s0012-821x(04)00035-4.

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SHIMIZU, Akihiko, Yoshinori YAGI, Hiroyuki YOSHIDA i Takehiko YOKOMINE. "Erosion of Gaseous Suspension Flow Duct due to Particle Collision, (I)". Journal of Nuclear Science and Technology 30, nr 9 (wrzesień 1993): 881–89. http://dx.doi.org/10.1080/18811248.1993.9734562.

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Rosenberg, C. L., A. Berger, N. Bellahsen i R. Bousquet. "Relating orogen width to shortening, erosion, and exhumation during Alpine collision". Tectonics 34, nr 6 (czerwiec 2015): 1306–28. http://dx.doi.org/10.1002/2014tc003736.

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Li, Yuzheng, Jintao Du, Yijun Lan, Heng Du i Hui Huang. "Numerical Analysis of the Factors Influencing the Erosion of the Valve Port of a High-Speed On/Off Valve". Applied Sciences 12, nr 12 (18.06.2022): 6212. http://dx.doi.org/10.3390/app12126212.

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Aiming at the problem of valve port erosion caused by contaminated particles, a three-dimensional prediction model of valve orifice erosion was established based on computational fluid dynamics (CFD) and erosion theory, considering the influence of the valve port eddy current on the oil flow. The discrete phase model (DPM) of fluent is used to obtain the orifice erosion location and erosion rate, and the causes of erosion of the high-speed on/off valve are analyzed. On this basis, several factors influencing valve port erosion are simulated to investigate the relationship between particle collision behavior and valve port erosion morphology under different factors, and the change rule of valve port erosion under different factors is analyzed. The results show that the high-speed on/off valve service life decreases with a larger cone angle of the spool, a larger pressure difference at the valve port, a larger proportion of large particle contaminants in the oil, a higher oil contamination level, and a larger filter aperture. In addition, the grey relational analysis method is used to clarify the pressure difference at the valve port, the particle size, and the filter aperture as the three most important factors affecting the erosion of the valve port of a high-speed on/off valve.

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Tabakoff, W., i M. Metwally. "Coating Effect on Particle Trajectories and Turbine Blade Erosion". Journal of Engineering for Gas Turbines and Power 114, nr 2 (1.04.1992): 250–57. http://dx.doi.org/10.1115/1.2906580.

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Gas turbine engines operating in dusty environments are exposed to erosion and performance deterioration. In order to improve the erosion resistance, nickel and cobalt superalloy blades and vanes are widely used in the hot section of gas turbines. Protective coatings have been used to enhance superalloy resistance to hot erosion. An investigation has been conducted to study coal ash particle dynamics and resulting blade erosion for both uncoated and coated blades of a two-stage axial flow gas turbine. A quasi-three-dimensional flow solution is obtained for each blade row for accurate computation of particle trajectories. The change in particle momentum due to collision with the turbine blades and casings is modeled using restitution parameters derived from three-component laser-Doppler velocimeter measurements. The erosion models for both blade superalloy and coatings are derived based on the erosion data obtained by testing the blade superalloy and coatings in a high-temperature erosion wind tunnel. The results show both the three-dimensional particle trajectories and the resulting blade impact locations for both uncoated and coated blade surfaces. In addition are shown the distribution of the erosion rate, impact frequency, impact velocity, and impact angle for the superalloy and the coating. The results indicate significant effects of the coating, especially on blade erosion and material deterioration.

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Gulick, Sean P. S., John M. Jaeger, Alan C. Mix, Hirofumi Asahi, Heinrich Bahlburg, Christina L. Belanger, Glaucia B. B. Berbel i in. "Mid-Pleistocene climate transition drives net mass loss from rapidly uplifting St. Elias Mountains, Alaska". Proceedings of the National Academy of Sciences 112, nr 49 (23.11.2015): 15042–47. http://dx.doi.org/10.1073/pnas.1512549112.

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Erosion, sediment production, and routing on a tectonically active continental margin reflect both tectonic and climatic processes; partitioning the relative importance of these processes remains controversial. Gulf of Alaska contains a preserved sedimentary record of the Yakutat Terrane collision with North America. Because tectonic convergence in the coastal St. Elias orogen has been roughly constant for 6 My, variations in its eroded sediments preserved in the offshore Surveyor Fan constrain a budget of tectonic material influx, erosion, and sediment output. Seismically imaged sediment volumes calibrated with chronologies derived from Integrated Ocean Drilling Program boreholes show that erosion accelerated in response to Northern Hemisphere glacial intensification (∼2.7 Ma) and that the 900-km-long Surveyor Channel inception appears to correlate with this event. However, tectonic influx exceeded integrated sediment efflux over the interval 2.8–1.2 Ma. Volumetric erosion accelerated following the onset of quasi-periodic (∼100-ky) glacial cycles in the mid-Pleistocene climate transition (1.2–0.7 Ma). Since then, erosion and transport of material out of the orogen has outpaced tectonic influx by 50–80%. Such a rapid net mass loss explains apparent increases in exhumation rates inferred onshore from exposure dates and mapped out-of-sequence fault patterns. The 1.2-My mass budget imbalance must relax back toward equilibrium in balance with tectonic influx over the timescale of orogenic wedge response (millions of years). The St. Elias Range provides a key example of how active orogenic systems respond to transient mass fluxes, and of the possible influence of climate-driven erosive processes that diverge from equilibrium on the million-year scale.

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Thum, Laurent, Reto De Paoli, Gérard M. Stampfli i Patrice Moix. "The Piolit, Pelat and Baiardo Upper Cretaceous flysch formations (western Alps): geodynamic implications at the time of the Pyrenean tectonic phases". Bulletin de la Société Géologique de France 186, nr 4-5 (1.07.2015): 209–21. http://dx.doi.org/10.2113/gssgfbull.186.4-5.209.

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AbstractThe Piolit, Pelat (French Alps) and Baiardo (Italian Maritime Alps) units contain Upper Cretaceous carbonate turbidites formations, with minor siliciclastic components. They are flysch formations, linked with the Pyrenean compressive events through their ages and their “subbriançonnais” structural position. Sedimentological, mineralogical (heavy minerals), and geochemical analysis, point to a potential “Pyrenean signature” which would testify the Late Cretaceous collision between the Ibero-Briançonnais terrane and the European plate. A “Dauphinois” origin and basin inversion erosion is proposed for the zircon-tourmaline-rutile (ZTR) bearing Piolit flysch, deposited from the Coniacian to the Campanian. A Penninic origin with tectonic inversion and erosion of former tilted blocks of the European margin from the Turonian to the Paleocene is proposed for the ZTR bearing Pelat flysch. Comparison with the Niesen (Swiss Prealps) and La Ciotat (Provence) flysch depositional context, allows to better constrain the Pyrenean compressive event in the Alpine domain. The Senonian part of the Baiardo flysch, that contains a garnet-dominated heavy mineral association and distinct geochemical trends, is allotted to the Liguro-Piemontais domain and to the Alpine collision stricto sensu.

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Okuyama, Keiichi. "Mechanical erosion characteristics of carbon-based materials by high-velocity particulate collision". TANSO 2005, nr 218 (2005): 185–91. http://dx.doi.org/10.7209/tanso.2005.185.

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Coker, E. Howard, i Dan Van Peursem. "The erosion of horizontal sand slurry pipelines resulting from inter-particle collision". Wear 400-401 (kwiecień 2018): 74–81. http://dx.doi.org/10.1016/j.wear.2017.12.022.

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Li, Shuxun, Bohao Zhang, Lingxia Yang, Jianzheng Zhang, Yixue Wang i Wenyu Kang. "Study on Wear Properties of the Graphite-Sealing Surfaces in a Triple Eccentric Butterfly Valve Based on EDEM-Fluent Coupling". Machines 11, nr 4 (7.04.2023): 463. http://dx.doi.org/10.3390/machines11040463.

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When using valves and pipes, erosion wear is a major issue. Erosion wear can result in equipment shutdown, material replacement, and other issues, as well as the failure of sealing surfaces. The depth of erosion wear is primarily determined by particle velocity, particle size, target material, and use conditions. A combination of the discrete element method (DEM) and computational fluid dynamics (CFD) was used in this study. The dynamic process of particle collision with the sealing surface is also considered. The wear depth was then calculated using Archard’s abrasive wear theory. The erosion wear process of the graphite-sealing surface by gas-solid two-phase flow medium is numerically simulated in a high-temperature triple eccentric butterfly valve using the above theory and method. The erosion wear patterns of graphite-sealing surfaces were investigated under various particle velocities, particle sizes, target materials, and service conditions. The findings indicate that particle velocity and particle size are positively related to wear rate. Soft target wear depth is greater than hard target wear depth. The wear depth decreases as the ambient temperature rises. As a result, graphite has excellent resistance to erosion and wear at high temperatures. When feeding, however, particle velocity and particle size must be considered. The erosion wears characteristics of a high temperature three eccentric butterfly valve investigated in this paper can be used to optimize erosion wear prevention.

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Yang, Guang, Linzhao Shu, Nan Ji i Zhipeng Qian. "Numerical study on the influence of anti-collision pontoon on the vortex behind pier tail and horse-shoe vortex around pier". Journal of Physics: Conference Series 2029, nr 1 (1.09.2021): 012149. http://dx.doi.org/10.1088/1742-6596/2029/1/012149.

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Abstract In order to study the influence of pier anti-collision pontoon on the vortex behind pier tail and horse-shoe vortex around pier, taking circular pier as an example, Reynolds stress (RSM) turbulence model is used to numerically simulate the flow around pier with anti-collision pontoon. Firstly, the rationality of the numerical simulation method and the accuracy of the results are verified by comparing with the cylindrical flow model test. Then, the bare pier is equipped with an anti-collision pontoon to calculate the flow around the pier under different water depths. The results show that the installation of anti-collision pontoon will change the vortex structure of the flow around the pier; the vortex in the pier tail will fuse obviously due to the interference of the floating tank, resulting in the non-stationary characteristics. When the water depth becomes shallow, the position of horse-shoe vortex in front of the pier will gradually close to the pier, and the bed erosion caused by horse-shoe vortex on both sides of the pier will be more serious.

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Chen, Juanjuan, Ning Guo, Hai Geng, Jing Hu, Yanlong Wang i Hao Yang. "Optimized design of the ion optics based on the over-perveance characteristics of the beam current". AIP Advances 13, nr 3 (1.03.2023): 035032. http://dx.doi.org/10.1063/5.0139014.

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To illustrate the erosion mechanism of the edge aperture by high-energy ions, a three-dimension simulation model was established, and a particle-in-cell method was applied in tracking the hitting processes as well as a Monte Carlo collision method was used to deal with the particles’ collision. Numerical results showed that the potentials interacted among the sheaths of adjacent holes and the beam ions were over-focused in the accelerator gap, causing some ions to be intercepted on the downstream wall of the decelerator grid. This was a typical under-perveance characteristic of the beam current, operating at significantly less than the optimal perveance and corresponding to lower beam currents than optimal combination, which pushed the sheath to the left farther into the plasma. The farther the grid was, the more serious erosion patterns developed. In addition, the charge exchange ions were attracted and bombarded on the decelerator and the accelerator grids, respectively. The ion optics of the 30 cm ion thruster was optimized from four-zone to three-zone, where the plasma density upstream of the screen grid was increased by 1.5% and the perveance characteristics of the beam ions were improved such that many ions struck the edge hole. The background pressure was reduced from 3.0 × 10−3 to 8.0 × 10−4 Pa to decrease the erosion depths of the grids caused by the charge exchange ions, about 9.09% and two orders of magnitude, respectively, for the accelerator and decelerator grids.

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Tabakoff, W., i M. F. Malak. "Laser Measurements of Fly Ash Rebound Parameters for Use in Trajectory Calculations". Journal of Turbomachinery 109, nr 4 (1.10.1987): 535–40. http://dx.doi.org/10.1115/1.3262144.

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This paper describes an experimental method used to find particle restitution coefficients. The equations that govern the motion of solid particles suspended by a compressible gas flow through a turbomachine depend on the restitution coefficients. Analysis of the data obtained by a laser-Doppler velocimeter (LDV) system of the collision phenomenon gives the restitution ratios as a function of the incidence angle. From these ratios, the particle velocity components after collision are computed and used as the initial conditions to the solution of the governing equations of motion for particle trajectories. The erosion of metals impacted by small dust particles can be calculated by knowing the restitution coefficients. The alloy used in this investigation was 410 stainless steel.

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Tabakoff, W., i A. Hamed. "The Dynamics of Suspended Solid Particles in a Two-Stage Gas Turbine". Journal of Turbomachinery 108, nr 2 (1.10.1986): 298–302. http://dx.doi.org/10.1115/1.3262051.

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Gas turbine engines operating in dusty environments are exposed to erosion and performance deterioration. In order to provide the basis for calculating the erosion and performance deterioration of turbines using pulverized coal, an investigation is undertaken to determine the three-dimensional particle trajectories in a two-stage turbine. The solution takes into account the influence of variation in the three-dimensional flow field. The change in particle momentum due to their collision with the turbine blades and casings is modeled using empirical equations derived from experimental laser-Doppler velocimetry (LDV) measurements. The results show the three-dimensional trajectory characteristics of the solid particles relative to the turbine blades. The results also show that the particle distributions in the flow field are determined by particle–blade impacts. The results obtained from this study indicate the turbine blade locations which are subjected to more blade impacts and hence more erosion damage.

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Thomson, Stuart N. "Late Cenozoic geomorphic and tectonic evolution of the Patagonian Andes between latitudes 42°S and 46°S: An appraisal based on fission-track results from the transpressional intra-arc Liquiñe-Ofqui fault zone". GSA Bulletin 114, nr 9 (1.09.2002): 1159–73. http://dx.doi.org/10.1130/0016-7606(2002)114<1159:lcgate>2.0.co;2.

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Abstract Fission-track (FT) thermochronology has been applied to investigate the low-temperature cooling and denudation history of the Patagonian Andes along the southern part of the intra-arc transpressional Liquiñe-Ofqui fault zone between 42° and 46°S. The Liquiñe-Ofqui fault is shown to have been the focus of enhanced cooling and denudation initiated between ca. 16 and 10 Ma. Several fault blocks with different cooling histories are identified; these are separated by major oblique- or reverse-slip faults proposed to form the eastern part of a major (crustal-scale) dextral transpression zone. Local very fast rates of cooling and denudation between ca. 7 and 2 Ma were coeval with collision of the Chile Rise (an active mid-oceanic ridge) with the Peru-Chile Trench between ∼47° and 48°S. This location is close to the southern termination of the Liquiñe-Ofqui fault, implying that the collision of the ridge was a major force driving late Cenozoic transpression. The lack of significant cooling and denudation before ca. 16 Ma is indicative of pure strike-slip or transtensional movement along the Liquiñe-Ofqui fault before the collision of the ridge. Digital landscape analysis supports glacial and periglacial erosion as the main contributor to denudation since ca. 7 Ma, leading to restriction of topographic development. The combination of transpression-induced rock uplift and glacial erosion is shown to be very effective at causing localized denudation. Anomalously young FT ages along the Liquiñe-Ofqui fault are attributed to the existence of a late Cenozoic localized heat-flow anomaly along the fault.

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Chen, Li, Han, Guo, Su i Wei. "Sediment Erosion Characteristics and Mechanism on Guide Vane End-Clearance of Hydro Turbine". Applied Sciences 9, nr 19 (2.10.2019): 4137. http://dx.doi.org/10.3390/app9194137.

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Sediment erosion caused by the collision of solid particles is a challenge for the safety, reliability, unit efficiency, and vibration noise of the hydroelectric engineering system located at China’s Yellow River and northwest inland basin. The sediment-laden flow of the guide vane end-clearance of the Francis Turbine at Dongshuixia hydroelectric station was used as the research object, and the large eccentric shaft structure of a guide vane was considered. Numerical calculations with the large eddy simulation (LES) and discrete phase models (DPMs) were carried out to study the erosion characteristics and mechanism of the end-surface of the guide vane and head cover, the flow mechanism of adverse erosion behind the shaft, and the influence law of the turbulence integral scale, turbulent kinetic energy, and turbulent flow angle on erosion. The flow field with a 1 mm clearance should set the number of particle trajectory per unit inlet area at about 1/mm2 to ensure the accuracy of calculation. The von Kármán vortex street is the main reason for adverse erosion behind the shaft and the low frequency energy of the turbulence plays a leading role in erosion. The above results provide a reference for the optimization design of an anti-wear guide vane and wear-protection of the clearance with sediment-laden water.

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31

Yoshida, Junya, i Osamu Sano. "Erosion of the granular layer due to the collision of a vortex ring". Fluid Dynamics Research 46, nr 6 (13.11.2014): 061421. http://dx.doi.org/10.1088/0169-5983/46/6/061421.

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32

Kurosaki, Kenji, i Shu-ichiro Inutsuka. "Giant Impact Events for Protoplanets: Energetics of Atmospheric Erosion by Head-on Collision". Astrophysical Journal 954, nr 2 (1.09.2023): 196. http://dx.doi.org/10.3847/1538-4357/ace9ba.

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Abstract Numerous exoplanets with masses ranging from Earth to Neptune and radii larger than Earth have been found through observations. These planets possess atmospheres that range in mass fractions from 1% to 30%, reflecting the diversity of atmospheric mass fractions. Such diversities are supposed to be caused by differences in the formation processes or evolution. Here, we consider head-on giant impacts onto planets causing atmosphere losses in the later stage of their formation. We perform smoothed particle hydrodynamic simulations to study the impact-induced atmosphere loss of young super-Earths with 10%–30% initial atmospheric mass fractions. We find that the kinetic energy of the escaping atmosphere is almost proportional to the sum of the kinetic impact energy and self-gravitational energy released from the merged core. We derive the relationship between the kinetic impact energy and the escaping atmosphere mass. The giant impact events for planets of comparable masses are required in the final stage of the popular scenario of rocky planet formation. We show it results in a significant loss of the atmosphere, if the impact is a head-on collision with comparable masses. This latter fact provides a constraint on the formation scenario of rocky planets with substantial atmospheres.

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33

Rolland, Yann, Antonin Bilau, Thibaut Cardinal, Ahmed Nouibat, Dorian Bienveignant, Louise Boschetti, Stéphane Schwartz i Matthias Bernet. "Bridging the Gap between Long–Term Orogenic Evolution (>10 Ma Scale) and Geomorphological Processes That Shape the Western Alps: Insights from Combined Dating Approaches". Geosciences 12, nr 11 (25.10.2022): 393. http://dx.doi.org/10.3390/geosciences12110393.

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Constraining the relative roles of erosion and tectonics in the evolution of mountain belts is a challenging scientific goal. In this review article on the Western Alps, we show how it becomes possible to “bridge the gap” between the long–term (>Ma) orogenic evolution controlled by tectonics and exhumation processes and the recent geomorphological evolution that is accessible on an annual–decadal basis. Advances in mineral dating that have grown in relation to deformation in the ductile and brittle crustal fields have allowed us to constrain the evolution of deformation through time and depth. A drastic change from early collision, dominated by rapid underthrusting of the European plate, to a more stagnant syn–collisional tectonic context is documented since about 26–20 Ma by syn–kinematic phengites and vein–hosted monazites along the Alpine arc. The overall dextral kinematic context is accompanied by local extensional domains in the Simplon and High Durance Valley. Activation of the Simplon ductile fault is documented from 20 Ma, whereas the High Durance extensional system commenced after 10 Ma. The application of cosmogenic nuclide dating of incised river gorges demonstrates that the erosion pattern of the Western Alps follows a different evolution within the valleys dominated by upstream glacial erosion than in peripheral watersheds devoid of glaciers. The very low peripheral incision is found to be similar to the vertical GPS signal, suggesting equilibrium of tectonic uplift and incision, whereas the glacial–dominated valleys exhibit significantly increased and transient river incision during interglacials and a constant ongoing tectonic regime.

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34

Fu, Tao, Zhixin Zhu, Yan Li, Yue Sun i Lingxiao Meng. "Study on the Time-dependent Reliability of Corroded Reinforced Concrete Bridge Structures due to Ship Impact". Advances in Civil Engineering 2022 (5.04.2022): 1–13. http://dx.doi.org/10.1155/2022/8190297.

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The cumulative damage caused by chloride ion erosion to coastal bridge structures reduces the ship impact resistance of channel bridge structures and leads to changes in reliability of bridge structures on ship impact. It is of great theoretical and practical significance to study the performance degradation change law of corroded bridge structures and to evaluate the ship impact time-dependent reliability of in-service corrosion-damaged bridge structures. Based on the durability decay model of reinforced concrete structures in a chloride ion erosion environment, the time-dependent resistance analysis of bridge structures is carried out considering the reduction of yield strength of longitudinal reinforcement and hoop reinforcement in pile sections and the decay of compressive strength of protective layer concrete. Based on the study of the probabilistic model and parameters of random variables affecting the time-dependent reliability of ship-bridge collision, the typical damage modes of bridge structures under ship impact are analyzed, the time-dependent reliability analysis model of bridge structures under ship impact is established based on the structural damage criterion, the ship-bridge crash limit state functional function is given, and the time-dependent reliability analysis of ship-bridge collision is carried out based on the response surface method.

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35

Fuchs, M. C., R. Gloaguen, S. Merchel, E. Pohl, V. A. Sulaymonova, C. Andermann i G. Rugel. "Millennial erosion rates across the Pamir based on <sup>10</sup>Be concentrations in fluvial sediments: dominance of topographic over climatic factors". Earth Surface Dynamics Discussions 3, nr 1 (29.01.2015): 83–128. http://dx.doi.org/10.5194/esurfd-3-83-2015.

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Abstract. The understanding of erosion processes is fundamental to study the evolution of actively deforming mountain ranges, whereas the relative contributions tectonic and climatic factors and their feedbacks are debated. The Pamir is peculiar in both, high deformation rates induced by the India–Eurasia collision and its position at the transition between Westerlies and Monsoon. In order to contribute to this debate we quantify basin-wide erosion rates from cosmogenic 10Be concentrations in modern river sediments measured by accelerator mass spectrometry. Sample locations represent the Panj basin at six sites along its trunk stream, and the major, east–west elongated tributary basins at five sites. An average erosion of ~0.64 mm yr−1 for the entire Pamir reveals a rapid landscape evolution. Erosion rates of tributary sub-basins highlight the strong contrast between the plateau (0.05 to 0.16 mm yr−1) and the Pamir margins (0.54 to 1.45 mm yr−1). The intensity of erosion is primarily (R2 of 0.81) correlated to slope steepness (0.75 quartiles) suggesting either tectonic uplift or base level lowering. Multiple linear regression reveals that precipitation may contribute also to the efficiency of erosion (R2 of 0.93) to a lesser extent. Dry conditions and low slopes hinders sediment transport and consequently, erosion on the plateau. The highest erosion coincides with the predominant winter precipitation from the Westerlies. The concentrated discharge during spring and early summer favors pronounced erosion along the north-western Pamir margin by driving the sediment flux out of the basins. The magnitude of erosion in Pamir is similar to rates determined in the south Himalayan escarpment, whereas climatic and tectonic conditions are very different. Millennial erosion does not balance the roughly ten times higher fluvial incision implying a transient landscape. We propose that river captures are responsible for the strong base level drop driving the incision along the Panj and consequently, initiate steep hillslopes that will contribute to high erosion at the Pamir margins. Precipitation may act as limiting factor to hillslope adjustment and consequently to erosion processes.

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Planes, María Belén, Emmanuel N. Millán, Herbert M. Urbassek i Eduardo M. Bringa. "Collisions between micro-sized aggregates: role of porosity, mass ratio, and impact velocity". Monthly Notices of the Royal Astronomical Society 503, nr 2 (5.03.2021): 1717–33. http://dx.doi.org/10.1093/mnras/stab610.

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ABSTRACT Dust aggregate collisions usually occur between mass-asymmetric collision partners. Granular-mechanics simulations are used to study the influence of filling factor, φ, and impact velocity in collisions of spherical granular aggregates with different values of their mass ratio, but the same filling factor. Three possible outcomes are observed: (i) sticking, which might include penetration of the smaller aggregate into the larger aggregate; (ii) fragmentation of the largest aggregate into two large fragments, particularly due to the so-called piston effect for low filling factors; and (iii) total destruction of the aggregates. Most of the impact energy is spent by friction, with some fraction leading to compaction of the porous material. The erosion efficiency varies significantly with impact velocity, mass ratio, and porosity, but the accretion efficiency does not show such strong variations. For highly asymmetric collisions with high impact velocities (≃100 m s−1), grain accretion (growth) can occur for a ‘window’ in the filling factor (0.20 < φ < 0.35). This window becomes wider as the impact velocity decreases. As the mass ratio of the aggregates decreases, the impact velocities that enable growth can also decrease. The mass distribution of the fragments follows a power-law distribution that is almost independent of the mass ratio, filling factor, and velocity.

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37

الجوهر, ساجدة, i سرحان الخفاجي. "تأثير العمليات المورفومناخية على المواقع الأثرية في منطقة الوركاء الحضارية". Uruk Journal 15, nr 3-P1 (22.09.2022): 1702–27. http://dx.doi.org/10.52113/uj05/022-15/1702-1727.

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The research dealt with analyzing the impact of morphoclimatic processes on the urban area of Al -Warkaa city, which represents the most important archaeological cities in southern Iraq region. The study aims to analyze the most important characteristics of natural geography and its role in the activity or weakness of morphoclimatic processes affecting archaeological sites, and the studies showed that the morphoclimatic processes on the Al-Warkaa historical region are most effective on the historical sites, which represented by chemical, biological and mechanical weathering processes and their different effects, Mechanical weathering is considered one of the most active types of weathering in the region, in addition to wind and rain processes erosion and its prominent impact on archaeological monuments. Through field work and the use of mathematical equations, the activity of morphoclimatic processes was measured. Represented by the processes of rain and wind erosion and the rates of annual climatic susceptibility to wind erosion, the evidence of erosion in the Samawah and Nasiriyah climatic stations was very high. It became clear that the processes of rain erosion have a clear and significant impact on the archaeological sites represented by collision and plate erosion and the erosion of water bodies and grooves, and the sedimentary morphoclimatic processes represented by rain and wind precipitation have a clear and significant effect represented by the burial of many archaeological sites in the historical region, and various environmental disturbances contribute, such as fluctuation and change Climatic and geological disturbances to a very large extent in the instability of those morpho-climatic and its effects on the study area.

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38

Jun, Yong-Du, i Widen Tabakoff. "Numerical Simulation of a Dilute Particulate Flow (Laminar) Over Tube Banks". Journal of Fluids Engineering 116, nr 4 (1.12.1994): 770–77. http://dx.doi.org/10.1115/1.2911848.

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This paper presents an investigation of numerical simulation for a dilute particle laden flow (laminar) over in-line tube banks. Particles behavior of two different sizes and density (100 μm sand and 40 μm fly ash) is demonstrated through the present study for a fixed geometry and flow condition, that is, a square in-line tube bank of two rows deep with pitch-to-diameter ratio of two at Reynolds number 400. Dilute particulate flow assumption is used and the drag force is considered as the only external force term that affects the particles behavior in the flow. Experimental rebounding data and semiempirical equation for the erosion estimation are used. It was found through the present simulation that the particles behavior of the different sizes and density in tube bank system is quite different in their trajectories, impact and the erosion pattern. The protective role of the first row of cylinders could be supported with respect to the particles collision on the cylinder but not necessarily to the erosion point of view. Also the information at impact such as the impact velocity and the impact angle which affect the erosion (Tabakoff et al., 1988) can be estimated by using the numerical simulation shown in the present study.

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39

Urbanovich, L. I., i E. M. Kramchenkov. "Erosion of steels and alloys in their collision with a flux of abrasive particles". Journal of Engineering Physics and Thermophysics 72, nr 3 (maj 1999): 496–502. http://dx.doi.org/10.1007/bf02699217.

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40

Clift, Peter D., Ingo Pecher, Nina Kukowski i Andrea Hampel. "Tectonic erosion of the Peruvian forearc, Lima Basin, by subduction and Nazca Ridge collision". Tectonics 22, nr 3 (czerwiec 2003): n/a. http://dx.doi.org/10.1029/2002tc001386.

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41

Addie, Ali, Raid Ismail i Mudhafar Mohammed. "2D Particle-in-Cell/Monte Carlo Collision Simulation of Zn-C Mosaic Target Erosion". Journal of Applied Sciences and Nanotechnology 2, nr 4 (1.11.2022): 118–27. http://dx.doi.org/10.53293/jasn.2022.5395.1185.

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42

Nielsen, Søren B. "A post mid-Cretaceous North Sea model". Bulletin of the Geological Society of Denmark 49 (2.12.2002): 187–204. http://dx.doi.org/10.37570/bgsd-2003-49-14.

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The relative importance and causal relationship between tectonics, eustacy and sediment charge is investigated for the post mid-Cretaceous North Sea. Guided by the predictions of a quantitative model and previously published work it is argued that the geological evolution comprises 1) continued subsidence of the central North Sea and its more marginal basin areas, related to Palaeozoic and Mesozoic lithospheric and deeper processes, 2) Cenozoic uplift of the British Isles (Scotland) and western Fennoscandia initiated by the Iceland plume in Paleocene/Eocene, 3) inversion zone dynamics induced by in-plane stress variations from plate boundary processes (the African-Eurasian collision and Atlantic spreading), and 4) denudation controlled by the availability of topography and erosional base level changes. The processes are consistent with the general present day sediment structure of the North Sea. Furthermore, they produced the pattern and amplitude of the burial anomalies in the North Sea region: 1) the continued subsidence of the central North Sea ensured maximum burial here at the present day, 2) Cenozoic uplift of the coastal areas of Scotland and western Fennoscandia, including southern Norway, produced over-burial that decreases away from the coast with a gradient that depends on the flexural strength of the lithosphere, 3) inversion zones (in particular the Sole Pit High and the Sorgenfrei-Tornquist Zone) developed a two phase burial anomaly, firstly by erosion of the narrow strip of topography in the central zone of inversion, and secondly by more regional erosion of the post-compressional rebound topography, involving both the central inversion zone and the marginal troughs. The falling eustatic level generated a burial anomaly by erosional unloading and isostatic uplift of the basin margins. Deep Quaternary erosion enhanced the burial anomaly in, for example, the Farsund Basin and the Skagerrak. The post-compressional rebound of the Sorgenfrei-Tornquist Zone is identified as the Neogene tectonic mechanism in the eastern North Sea area.

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43

Koons, P. O. "Two-sided orogen: Collision and erosion from the sandbox to the Southern Alps, New Zealand". Geology 18, nr 8 (1990): 679. http://dx.doi.org/10.1130/0091-7613(1990)018<0679:tsocae>2.3.co;2.

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Yoshida, Junya, Naoya Masuda, Boku Ito, Takayoshi Furuya i Osamu Sano. "Collision of a vortex ring on granular material. Part II. Erosion of the granular layer". Fluid Dynamics Research 44, nr 1 (19.01.2012): 015502. http://dx.doi.org/10.1088/0169-5983/44/1/015502.

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45

Ellis, Susan, i Christopher Beaumont. "Models of convergent boundary tectonics: implications for the interpretation of Lithoprobe data". Canadian Journal of Earth Sciences 36, nr 10 (1.10.1999): 1711–41. http://dx.doi.org/10.1139/e99-075.

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Physical models of convergent boundary processes can provide insights into compressional orogens such as those studied by Lithoprobe. We summarize the qualitative tectonic style of a series of models designed to explore behaviour in subduction, collision, and obliquely convergent settings. The model results are represented by a series of diagrams which emphasize the main controls and behaviours in each case. Models are categorized in terms of the three main types of control: B, the boundary conditions assumed to operate on crust from surrounding lithosphere; I, the internal properties such as rheology and temperature distribution; and T, the redistribution of thickened crust or excess mass by gravitational forces (flexural compensation) and by surface processes such as erosion and deposition. The model templates for each setting are used to interpret some of the orogens studied by Lithoprobe, where there are sufficient temporal and spatial data for such a comparison to be meaningful. The purpose is to examine conceptual evolutions proposed by geologists and geophysicists in a process-based way. We compare the evolution of the Cascadia subduction margin with templates for oblique subduction; the eastern Trans-Hudson Orogen with models of the transition from subduction to collision; the Appalachian Transect in Lithoprobe East with models that involve a weak interior ("vise" models); the Torngat and New Quebec orogens with templates of subduction, transition to collision, and vise models; and the evolution of the Abitibi-Opatica granite-greenstone belt with models of subduction and collision. Comparison between models and seismic transects also highlights some of the potential pitfalls in interpreting compressional structures using reflectivity fabric.

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46

Wu, Jiandong, Jiyun Xu i Hao Wang. "Numerical simulation of micron and submicron droplets in jet impinging". Advances in Mechanical Engineering 10, nr 10 (październik 2018): 168781401880531. http://dx.doi.org/10.1177/1687814018805319.

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Micron droplet deposition onto a wall in an impinging jet is important for various applications like spray cooling, coating, fuel injection, and erosion. The impinging process is featured by abrupt velocity changes and thus complicated behaviors of the droplets. Either modeling or experiment for the droplet behaviors is still challenging. This study conducted numerical modeling and compared with an existing experiment in which concentric dual-ring deposition patterns of micron droplets were observed on the impinging plate. The modeling fully took into account of the droplet motion in the turbulent flow, the collision between the droplets and the plate, as well as the collision, that is, agglomeration among droplets. Different turbulence models, that is, the v2− f model, standard k–ε model, and Reynolds stress model, were compared. The results show that the k–ε model failed to capture the turbulent flow structures and overpredicted the turbulent fluctuations near the wall. Reynolds stress model had a good performance in flow field simulation but still failed to reproduce the dual-ring deposition pattern. Only the v2− f model reproduced the dual-ring pattern when coupled with droplet collision models. The results echoed the excellent performance of the v2− f model in the heat transfer calculation for the impinging problems. The agglomeration among droplets has insignificant influence on the deposition.

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47

Vigolo, D., I. M. Griffiths, S. Radl i H. A. Stone. "An experimental and theoretical investigation of particle–wall impacts in a T-junction". Journal of Fluid Mechanics 727 (20.06.2013): 236–55. http://dx.doi.org/10.1017/jfm.2013.200.

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AbstractUnderstanding the behaviour of particles entrained in a fluid flow upon changes in flow direction is crucial in problems where particle inertia is important, such as the erosion process in pipe bends. We present results on the impact of particles in a T-shaped channel in the laminar–turbulent transitional regime. The impacting event for a given system is described in terms of the Reynolds number and the particle Stokes number. Experimental results for the impact are compared with the trajectories predicted by theoretical particle-tracing models for a range of configurations to determine the role of the viscous boundary layer in retarding the particles and reducing the rate of collision with the substrate. In particular, a two-dimensional model based on a stagnation-point flow is used together with three-dimensional numerical simulations. We show how the simple two-dimensional model provides a tractable way of understanding the general collision behaviour, while more advanced three-dimensional simulations can be helpful in understanding the details of the flow.

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48

Zhang, Ri, Dong Zhu, Haixiao Liu i Yong Liu. "Random process of particle-wall collision and its application in numerical simulation of solid particle erosion". Wear 452-453 (lipiec 2020): 203288. http://dx.doi.org/10.1016/j.wear.2020.203288.

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Kuznetsov, N. B. "The Cambrian Baltica-Arctida collision, pre-Uralide-Timanide orogen, and its erosion products in the Arctic". Doklady Earth Sciences 411, nr 2 (grudzień 2006): 1375–80. http://dx.doi.org/10.1134/s1028334x06090091.

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Itzkin, Michael, Laura J. Moore, Peter Ruggiero, Sally D. Hacker i Reuben G. Biel. "The relative influence of dune aspect ratio and beach width on dune erosion as a function of storm duration and surge level". Earth Surface Dynamics 9, nr 5 (13.09.2021): 1223–37. http://dx.doi.org/10.5194/esurf-9-1223-2021.

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Abstract. Dune height is an important predictor of impact during a storm event given that taller dunes have a lower likelihood of being overtopped than shorter dunes. However, the temporal dominance of the wave collision regime, wherein volume loss (erosion) from the dune occurs through dune retreat without overtopping, suggests that dune width must also be considered when evaluating the vulnerability of dunes to erosion. We use XBeach, a numerical model that simulates hydrodynamic processes, sediment transport, and morphologic change, to analyze storm-induced dune erosion as a function of dune aspect ratio (i.e., dune height versus dune width) for storms of varying intensity and duration. We find that low aspect ratio (low and wide) dunes lose less volume than high aspect ratio (tall and narrow) dunes during longer and more intense storms when the beach width is controlled for. In managed dune scenarios, where sand fences are used to construct a “fenced” dune seaward of the existing “natural” dune, we find that fenced dunes effectively prevent the natural dune behind them from experiencing any volume loss until the fenced dune is sufficiently eroded, reducing the magnitude of erosion of the natural dune by up to 50 %. We then control for dune morphology to assess volume loss as a function of beach width and confirm that beach width exerts a significant influence on dune erosion; a wide beach offers the greatest protection from erosion in all circumstances while the width of the dune determines how long the dune will last under persistent scarping. These findings suggest that efforts to maintain a wide beach may be effective at protecting coastal communities from dune loss. However, a trade-off may exist in maintaining wide beaches and dunes in that the protection offered in the short-term must be considered in concert with potentially long-term detrimental effects of limiting overwash, a process which is critical to maintaining island elevation as sea level rises.

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