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Residual ultimate strength prediction of monopile foundation of offshore wind turbine subjected to pitting
Published in Selma Ergin, C. Guedes Soares, Sustainable Development and Innovations in Marine Technologies, 2022
where v is wave velocity, V˙ is fluid particle acceleration, A is cross sectional area, D is diameter of monopile, ρ is mass density of the fluid, CA is added mass coefficient and CD is drag coefficient.
Particle Characterization and Dynamics
Published in Wen-Ching Yang, Handbook of Fluidization and Fluid-Particle Systems, 2003
Gibilaro et al. (1990) have subsequently corrected Eq. (155) for the added or virtual mass effect due to the fluid acceleration that accompanies particle acceleration. The correction involves adding ρ/2 to both ρp and ρ wherever they occur in the equation, as well as multiplying the second term in the equation by a factor exceeding unity that approaches unity as ρ/ρp approaches zero. However, since this correction only becomes important as ρ/ρp approaches unity, i.e., under conditions when the LHS of Eq. (155) will in most cases be positive whether or not the correction is applied (and will hence indicate particulate fluidization, in agreement with experiment), and given the experimental uncertainty involved in pinpointing regime transitions, this added complication can be safely dispensed with, at least for purposes of predicting aggregative vs. particulate fluidization.
Theory of elasticity and numerical methods in engineering
Published in Indrajit Chowdhury, Shambhu P. Dasgupta, Dynamics of Structure and Foundation – A Unified Approach, 2008
Indrajit Chowdhury, Shambhu P. Dasgupta
The particle acceleration is obtained from the material derivative of the velocity ai=∂vi∂t+vj∂vi∂xj
Preliminary Neutronics Study of an Accelerator-Driven Molten Spallation Target–Molten Lithium Source of Tritium
Published in Fusion Science and Technology, 2023
Michal Cihlář, Slavomír Entler, Tomáš Czakoj, Václav Dostál, Jan Prehradný, Pavel Zácha
The particles, usually protons or deuterons, are accelerated in a particle accelerator and directed to the molten spallation target. The accelerated particles cause a spallation reaction on nuclei of lead or bismuth. The spallation reaction is a fragmentation of a heavy nucleus into small fragments and neutrons. More about the spallation reactions theory, experiments, and utilization can be found in the Handbook of Spallation Research: Theory, Experiments and Applications14 and other works.15,16 From the spallation reaction, about 20 to 30 spallation neutrons commonly are created depending on incident proton energy.
Impact of neutron irradiation on electronic carrier transport properties in Ga2O3 and comparison with proton irradiation effects
Published in Radiation Effects and Defects in Solids, 2023
Jonathan Lee, Andrew C. Silverman, Elena Flitsiyan, Minghan Xian, Fan Ren, S. J. Pearton
Proton irradiation is performed using a high-energy charged particle beam generated by cyclotron. A cyclotron is a particle accelerator which uses the Lorentz force to accelerate charged particles to high speeds. In the absence of an electric field component, electrons moving perpendicular to magnetic fields will exhibit uniform circular motion. The magnetic field is omitted from a slab which lies parallel to the magnetic field. In this region, after exiting the magnetic field, an electric field is applied to accelerate the charged particles before entering another magnetic field region. The circular motion radius enlarges each time an acceleration is applied in the magnetically blank region, consistent with its higher velocity. Using this relatively simple method, high energies can be imparted to charged particles. Charged particles can be accelerated to relativistic speeds and a beam can be sustained. This method is used here for proton irradiation using a MC-50 Cyclotron at the Korea Institute of Radiological and Medical Science with the proton energy 10-MeV. The proton beam was injected into a low-vacuum chamber, where the β-Ga2O3-based devices were loaded, facing the proton beam. The average beam-current, measured by Faraday-cup, was 100 nA during the proton irradiation process. Proton fluence was fixed at 1014 cm−2. The room scattering or temperature value of L was ∼340 nm for the nonirradiated sample and decreased with increasing temperature due to increased recombination. After proton irradiation, the room temperature diffusion length was reduced to ∼315 nm. The values of the activation energy according to equation (4) were 41.8 and 16.2 meV and the asymptotic L0 values were 145 and 228 nm for the nonirradiated and proton irradiated samples, respectively. The main defect created in Ga2O3 by proton irradiation has been identified as a Ga vacancy with two hydrogens attached [76].