Bibliographies thématiques / Fast particles

Littérature scientifique sur le sujet « Fast particles »

Auteur : Grafiati
Publié le 8 juin 2024

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Articles de revues sur le sujet "Fast particles"

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Almerol, Jenny Lynn Ongue, et Marissa Pastor Liponhay. « Clustering of fast gyrotactic particles in low-Reynolds-number flow ». PLOS ONE 17, no 4 (7 avril 2022) : e0266611. http://dx.doi.org/10.1371/journal.pone.0266611.

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Systems of particles in turbulent flows exhibit clustering where particles form patches in certain regions of space. Previous studies have shown that motile particles accumulate inside the vortices and in downwelling regions, while light and heavy non-motile particles accumulate inside and outside the vortices, respectively. While strong clustering is generated in regions of high vorticity, clustering of motile particles is still observed in fluid flows where vortices are short-lived. In this study, we investigate the clustering of fast swimming particles in a low-Reynolds-number turbulent flow and characterize the probability distributions of particle speed and acceleration and their influence on particle clustering. We simulate gyrotactic swimming particles in a cubic system with homogeneous and isotropic turbulent flow. Here, the swimming velocity explored is relatively faster than what has been explored in other reports. The fluid flow is produced by conducting a direct numerical simulation of the Navier-Stokes equation. In contrast with the previous results, our results show that swimming particles can accumulate outside the vortices, and clustering is dictated by the swimming number and is invariant with the stability number. We have also found that highly clustered particles are sufficiently characterized by their acceleration, where the increase in the acceleration frequency distribution of the most clustered particles suggests a direct influence of acceleration on clustering. Furthermore, the acceleration of the most clustered particles resides in acceleration values where a cross-over in the acceleration PDFs are observed, an indicator that particle acceleration generates clustering. Our findings on motile particles clustering can be applied to understanding the behavior of faster natural or artificial swimmers.
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Liang, Yongshi, Cliff Y. Guo, Xianglong Zhao, Qiang Qin, Yi Cheng et Lixin He. « CPFD simulation on particle behaviour in an entrained-flow gasifier ». Clean Energy 4, no 1 (4 février 2020) : 75–84. http://dx.doi.org/10.1093/ce/zkz032.

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Abstract A computational particle fluid dynamics simulation model for entrained-flow gasification was established in this study. The simulation results agree with the experimental data. The detailed particle information and residence-time distribution were obtained by injecting particle tracers in the simulation. The results show that the particles in the gasifier can be classified into three flowing zones, i.e. a fast-flowing zone, a recirculation zone and a spreading zone. The criterion for this classification was also provided. The rapid gas expansion caused by the fast reactions plays a significant role in forming the particle stream into these three zones. It accelerates the particles in the centre of the gasifier while pushing the particles near the expansion edge into the gas recirculation. Also, the concentrated oxygen distribution in the gasifier results in the formation of high- and low-temperature regions. The particles in the fast-flowing zone flow directly through the high-temperature region and most of these particles in this zone were fully reacted with a short residence time. Since particles in the recirculation zone are in a relatively low-temperature region, most of these particles are not fully gasified, although with a long residence time. The rest of particles in the spreading zone show moderate properties between the above two zones.
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Tully, Christopher G. « Fast timing for collider detectors ». International Journal of Modern Physics A 31, no 33 (22 novembre 2016) : 1644022. http://dx.doi.org/10.1142/s0217751x1644022x.

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Advancements in fast timing particle detectors have opened up new possibilities to design [Formula: see text] collider detectors that fully reconstruct and separate event vertices and individual particles in the time domain. The applications of these techniques are considered for the physics at CEPC.
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Fiore, Andrew M., et James W. Swan. « Fast Stokesian dynamics ». Journal of Fluid Mechanics 878 (17 septembre 2019) : 544–97. http://dx.doi.org/10.1017/jfm.2019.640.

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We present a new method for large scale dynamic simulation of colloidal particles with hydrodynamic interactions and Brownian forces, which we call fast Stokesian dynamics (FSD). The approach for modelling the hydrodynamic interactions between particles is based on the Stokesian dynamics (SD) algorithm (J. Fluid Mech., vol. 448, 2001, pp. 115–146), which decomposes the interactions into near-field (short-ranged, pairwise additive and diverging) and far-field (long-ranged many-body) contributions. In FSD, the standard system of linear equations for SD is reformulated using a single saddle point matrix. We show that this reformulation is generalizable to a host of particular simulation methods enabling the self-consistent inclusion of a wide range of constraints, geometries and physics in the SD simulation scheme. Importantly for fast, large scale simulations, we show that the saddle point equation is solved very efficiently by iterative methods for which novel preconditioners are derived. In contrast to existing approaches to accelerating SD algorithms, the FSD algorithm avoids explicit inversion of ill-conditioned hydrodynamic operators without adequate preconditioning, which drastically reduces computation time. Furthermore, the FSD formulation is combined with advanced sampling techniques in order to rapidly generate the stochastic forces required for Brownian motion. Specifically, we adopt the standard approach of decomposing the stochastic forces into near-field and far-field parts. The near-field Brownian force is readily computed using an iterative Krylov subspace method, for which a novel preconditioner is developed, while the far-field Brownian force is efficiently computed by linearly transforming those forces into a fluctuating velocity field, computed easily using the positively split Ewald approach (J. Chem. Phys., vol. 146, 2017, 124116). The resultant effect of this field on the particle motion is determined through solution of a system of linear equations using the same saddle point matrix used for deterministic calculations. Thus, this calculation is also very efficient. Additionally, application of the saddle point formulation to develop high-resolution hydrodynamic models from constrained collections of particles (similar to the immersed boundary method) is demonstrated and the convergence of such models is discussed in detail. Finally, an optimized graphics processing unit implementation of FSD for mono-disperse spherical particles is used to demonstrated performance and accuracy of dynamic simulations of $O(10^{5})$ particles, and an open source plugin for the HOOMD-blue suite of molecular dynamics software is included in the supplementary material.
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Yu, X. Y., J. P. Cowin, M. J. Iedema et H. Ali. « Fast time-resolved aerosol collector : proof of concept ». Atmospheric Measurement Techniques Discussions 3, no 3 (1 juin 2010) : 2515–34. http://dx.doi.org/10.5194/amtd-3-2515-2010.

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Abstract. Atmospheric particles can be collected in the field on substrates for subsequent laboratory analysis via chemically sensitive single particle methods such as scanning electron microscopy with energy dispersive x-ray analysis. With moving substrates time resolution of seconds to minutes can be achieved. In this paper, we demonstrate how to increase the time resolution when collecting particles on a substrate to a few milliseconds to provide real-time information. Our fast time-resolved aerosol collector ("Fast-TRAC") microscopically observes the particle collection on a substrate and records an on-line video. Particle arrivals are resolved to within a single frame (4–17 ms in this setup), and the spatial locations are matched to the subsequent single particle analysis. This approach also provides in-situ information on particle size and number concentration. Applications are expected in airborne studies of cloud microstructure, pollution plumes, and surface long-term monitoring.
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Yu, X. Y., J. P. Cowin, M. J. Iedema et H. Ali. « Fast time-resolved aerosol collector : proof of concept ». Atmospheric Measurement Techniques 3, no 5 (12 octobre 2010) : 1377–84. http://dx.doi.org/10.5194/amt-3-1377-2010.

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Abstract. Atmospheric particles can be collected in the field on substrates for subsequent laboratory analysis via chemically sensitive single particle methods such as scanning electron microscopy with energy dispersive x-ray analysis. With moving substrates time resolution of seconds to minutes can be achieved. In this paper, we demonstrate how to increase the time resolution when collecting particles on a substrate to a few milliseconds to provide real-time information. Our fast time-resolved aerosol collector ("Fast-TRAC") microscopically observes the particle collection on a substrate and records an on-line video. Particle arrivals are resolved to within a single frame (4–17 ms in this setup), and the spatial locations are matched to the subsequent single particle analysis. This approach also provides in-situ information on particle size and number concentration. Applications are expected in airborne studies of cloud microstructure, pollution plumes, and surface long-term monitoring.
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Liu, Jinxian, Ye Chen, Bingbing Ni, Wei Ren, Zhenbo Yu et Xiaoyang Huang. « Fast Fluid Simulation via Dynamic Multi-Scale Gridding ». Proceedings of the AAAI Conference on Artificial Intelligence 37, no 2 (26 juin 2023) : 1675–82. http://dx.doi.org/10.1609/aaai.v37i2.25255.

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Recent works on learning-based frameworks for Lagrangian (i.e., particle-based) fluid simulation, though bypassing iterative pressure projection via efficient convolution operators, are still time-consuming due to excessive amount of particles. To address this challenge, we propose a dynamic multi-scale gridding method to reduce the magnitude of elements that have to be processed, by observing repeated particle motion patterns within certain consistent regions. Specifically, we hierarchically generate multi-scale micelles in Euclidean space by grouping particles that share similar motion patterns/characteristics based on super-light motion and scale estimation modules. With little internal motion variation, each micelle is modeled as a single rigid body with convolution only applied to a single representative particle. In addition, a distance-based interpolation is conducted to propagate relative motion message among micelles. With our efficient design, the network produces high visual fidelity fluid simulations with the inference time to be only 4.24 ms/frame (with 6K fluid particles), hence enables real-time human-computer interaction and animation. Experimental results on multiple datasets show that our work achieves great simulation acceleration with negligible prediction error increase.
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Liu, De-Ling. « Evaluating Aerosol Aspiration Efficiency in Fast-moving Air ». Journal of the IEST 56, no 2 (1 octobre 2013) : 20–28. http://dx.doi.org/10.17764/jiet.56.2.5600210764m14370.

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Sampling representative aerosol particles in fast-moving air is a challenging task. Aerosols are significantly more massive than gas molecules, thus they might not follow air streamlines well and could be more easily subjected to sampling errors. This work examines the physical factors that govern the aspiration efficiency of an aerosol sampling probe in unidirectional moving air, and explores the plausible sampling deviations under various high air velocity scenarios. The particle sizes of 0.5 and 5 μm are of particular interest due to their use in defining air cleanliness levels in ISO 14644-1[1] and FED-STD-209.[2]* Our analytical results indicate that significant sampling errors could occur for 5-μm particles when a thick-walled sampling probe is used, or when the air velocity at the sampling probe inlet does not match the velocity of the incoming air (i.e., anisokinetic sampling). The aspiration efficiency of 0.5-μm particles, on the other hand, is nearly 100% due to sufficiently small inertia of these particles.
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WU, JIAWEN, FENGQUAN ZHANG et XUKUN SHEN. « GPU-BASED FLUID SIMULATION WITH FAST COLLISION DETECTION ON BOUNDARIES ». International Journal of Modeling, Simulation, and Scientific Computing 03, no 01 (mars 2012) : 1240003. http://dx.doi.org/10.1142/s179396231240003x.

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In this paper, we present a method for fluid simulation based on smoothed particle hydrodynamic (SPH) with fast collision detection on boundaries on GPU. The major goal of our algorithm is to get a fast SPH simulation and rendering on GPU. Additionally, our algorithm has the following three features: At first, to make the SPH method GPU-friendly, we introduce a spatial hash method for neighbor search. After sorting the particles based on their grid index, neighbor search can be done quickly on GPU. Second, we propose a fast particle-boundary collision detection method. By precomputing the distance field of scene boundaries, collision detection's computing cost arrived as O(n), which is much faster than the traditional way. Third, we propose a pipeline with fine-detail surface reconstruction, and progressive photon mapping working on GPU. We experiment our algorithm on different situations and particle numbers of scenes, and find out that our method gets good results. Our experimental data shows that we can simulate 100K particles, and up to 1000K particles scene at a rate of approximately 2 times per second.
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Zhang, Hao, Lorenzo Sironi et Dimitrios Giannios. « Fast Particle Acceleration in Three-dimensional Relativistic Reconnection ». Astrophysical Journal 922, no 2 (1 décembre 2021) : 261. http://dx.doi.org/10.3847/1538-4357/ac2e08.

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Abstract Magnetic reconnection is invoked as one of the primary mechanisms to produce energetic particles. We employ large-scale 3D particle-in-cell simulations of reconnection in magnetically dominated (σ = 10) pair plasmas to study the energization physics of high-energy particles. We identify an acceleration mechanism that only operates in 3D. For weak guide fields, 3D plasmoids/flux ropes extend along the z-direction of the electric current for a length comparable to their cross-sectional radius. Unlike in 2D simulations, where particles are buried in plasmoids, in 3D we find that a fraction of particles with γ ≳ 3σ can escape from plasmoids by moving along z, and so they can experience the large-scale fields in the upstream region. These “free” particles preferentially move in z along Speiser-like orbits sampling both sides of the layer and are accelerated linearly in time—their Lorentz factor scales as γ ∝ t, in contrast to γ ∝ t in 2D. The energy gain rate approaches ∼eE rec c, where E rec ≃ 0.1B 0 is the reconnection electric field and B 0 the upstream magnetic field. The spectrum of free particles is hard, dN free / d γ ∝ γ − 1.5 , contains ∼20% of the dissipated magnetic energy independently of domain size, and extends up to a cutoff energy scaling linearly with box size. Our results demonstrate that relativistic reconnection in GRB and AGN jets may be a promising mechanism for generating ultra-high-energy cosmic rays.
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Thèses sur le sujet "Fast particles"

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Müller, Matthias S. « Fast algorithms for the simulation of granular particles ». [S.l. : s.n.], 2001. http://www.bsz-bw.de/cgi-bin/xvms.cgi?SWB9716193.

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Zegenhagen, Stefan. « Destabilization of Alfvén eigenmodes by fast particles in W7-AS ». [S.l.] : [s.n.], 2006. http://deposit.ddb.de/cgi-bin/dokserv?idn=984442553.

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Pinches, Simon David. « Nonlinear interaction of fast particles with Alfven waves in tokamaks ». Thesis, University of Nottingham, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.362917.

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Lilley, Matthew Keith. « Resonant interaction of fast particles with Alfvén waves in spherical tokamaks ». Thesis, Imperial College London, 2009. http://hdl.handle.net/10044/1/5487.

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The Spherical Tokamak (ST) concept has become one of the main avenues in magnetic nuclear fusion research since STs successfully demonstrated plasma operation at [Beta] = 2P[mu]0=B2~1. Next step ST machines aiming at achieving burning plasma conditions in high [Beta] plasmas are being planned, such as the Spherical Tokamak Power Plant (STPP) and the Component Testing Facility (CTF). Instabilities of fast particle-driven Alfven eigenmodes are often observed in present-day STs. Such instabilities, driven by fusion-born alpha particles as well as by fast ions produced with auxiliary heating schemes, in the next step STs may pose a major problem as these instabilities may affect confinement and losses of the fast ions. A theory of compressional Alfven eigenmodes (CAE) with frequencies above the deuterium cyclotron frequency,[omega] > [omega]cD, is developed for plasma parameters of a STPP, and modes in the ion-ion hybrid frequency range, [omega]cT < [omega] < [omega]cD, are also investigated in order to assess the potential of diagnosing the deuterium-tritium (D-T) ratio. For the 1-D character of a STPP equilibrium with [Beta]~1 , a `hollow cylinder' toroidal plasma model is employed for studying CAEs with arbitrary values of the parallel wave-vector k[||] = k[.]B/|B|. The existence of weakly-damped CAEs, free of mode conversion, is shown to be associated with the `well' in the magnetic field profile, B = B (R), that can exist at the magnetic axis. A significant part of this thesis focusses on the experimentally observed effects of resonant wave-particle interaction between Alfven waves and fast particles in the Mega Amp Spherical Tokamak (MAST) device at the Culham Laboratory, UK, and in the LArge Plasma Device (LAPD) in the University of California, Los-Angeles, USA. New robust experimental scenarios for exciting CAEs in the MAST spherical tokamak are developed, and interpretation of the observed CAEs in the frequency range [omega]cD/3 < [omega] < [omega]cD is given in the context of the 1-D ST model and the Doppler shifted cyclotron resonance. The e ciency of the Doppler resonance between co and counter directed fast ions and left and right hand polarised Alfven waves is further assessed experimentally on the LAPD device, with probe ions injected in the presence of Alfv en waves launched by an external antenna. The developed theory of CAEs is then applied to a calculation of the linear kinetic drive of CAEs in the MAST experiments. A model representation of the fast ion distribution function, produced by neutral beam injection (NBI), is used by fitting to the TRANSP Monte-Carlo NBI modelling results. The main free energy sources associated with temperature anisotropy and bump-on-tail are estimated analytically, and the CAE stability boundary is qualitatively assessed. In order to explain the experimentally observed difference between steady-state and pulsating Alfvenic modes, the non-linear theory of fast particle driven modes near marginal stability is extended to include dynamical friction (drag). For the bump-on-tail problem, the drag is shown to always give an explosive amplitude evolution in contrast to diffusion in velocity space in the vicinity of the wave-particle resonance. This is then extended to the case of experimentally observed NBI-driven toroidal Alfven eigenmodes (TAEs) in the MAST machine. The experimentally observed differences between TAEs driven by fast ions produced with ion cyclotron resonance heating (ICRH) and NBI are then interpreted. The problem of drag dominated collisions for modes excited by fusion-born alpha particles in burning plasmas such as a STPP and ITER is underlined.
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Vincenzi, Pietro. « Interaction between neutral beam fast particles and plasma in fusion experiments ». Doctoral thesis, Università degli studi di Padova, 2016. http://hdl.handle.net/11577/3424363.

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Neutral beam injection (NBI) is one of the most used and reliable methods to heat plasmas in magnetically confined fusion devices. NBI is used in most of the present experiments, it will be used as dominant auxiliary power system in ITER experiment and studies are ongoing for DEMO reactor preconceptual designs with neutral beam (NB) systems. NBI is an essential actuator for plasma scenarios in terms of heating and driven current. This thesis presents the work performed during the 3 years of my Ph.D.. It focuses on numerical studies of the interaction between energetic particles coming from NBI and magnetically confined hot plasmas. The main aspects discussed in this thesis are the neutral beam ionization, fast ion confinement, fast ion losses, power deposition and driven current. A brief discussion of NBI as fuelling source is also presented. NBI modelling tools have been applied to study different devices with dominant NB power: the largest tokamak in operation (JET), the largest helical device in operation (LHD) and DEMO tokamak reactor concept. Detailed modelling of NBI by means of a Monte Carlo orbit following code has been provided for JET discharge analyses. A predictive simulation aimed at reconstructing the ion temperature profile with strong ion heating from NBI has been performed, resulting in a reliable prediction when the experimental measurement was not available due to a diagnostic fault. JET NBI-plasma interaction has been studied by predictive simulations for H discharges starting from reference D discharges in support of JET isotope studies. The isotopic change and the consequent effect on NBI-plasma interaction has been discussed also for LHD helical device, where studies in preparation of future D experiments (instead of H) are ongoing. NBI is one of the options as additional power system for a demonstrative fusion power plant (DEMO), and a pre-conceptual design of the reactor is ongoing within EUROfusion activities. DEMO scenario simulations have been carried out both for pulsed and steady-state concepts. The role of NBI as dominant heating and current drive system has been investigated by sensitivity studies, comparisons with other heating systems and transport investigations of transient phases (plasma ramp-up and ramp-down).
L’iniezione di fasci di particelle neutre (neutral beam injection NBI) é uno dei metodi piú utilizzati e affidabili per scaldare il plasma in esperimenti sulla fusione termonucleare confinata magneticamente. L’NBI é utilizzato nella maggior parte degli attuali esperimenti, verrá applicato come riscaldamento dominante in ITER e studi sono in corso per implementare l’NBI nel progetto europeo del futuro reattore dimostrativo DEMO. L’NBI gioca un ruolo fondamentale per i plasmi fusionistici in termini di riscaldamento e capacitá di indurre corrente nel plasma. Questa tesi presenta il lavoro svolto durante i tre anni del mio dottorato e si focalizza su studi numerici dell’interazione tra particelle energetiche provenienti dall’NBI e plasmi confinati magneticamente. Gli aspetti principali discussi sono la ionizzazione del fascio di neutri nel plasma, il confinamento e le perdite degli ioni veloci, la deposizione di potenza e la corrente di plasma indotta dal fascio. Viene inoltre presentata una breve discussione sull’NBI come sorgente di particelle. Diversi codici numerici sono stati applicati per lo studio di esperimenti caratterizzati da un riscaldamento dominante tramite NBI: sono stati studiati il piú grande tokamak attivo al mondo (JET), il piú grande stellarator attivo al mondo (LHD) e il progetto del reattore dimostrativo europeo DEMO. Accurate simulazioni dell’iniezione del fascio neutro sono state elaborate grazie ad un codice Monte Carlo per l’analisi di esperimenti di JET. Una simulazione predittiva é stata condotta con l’intento di ricostruire il profilo di temperature ionica del plasma nel caso di rilevante riscaldamento ionico da parte dell’NBI. Ció ha prodotto un’attendibile ricostruzione in un caso in cui le misure sperimentali non erano disponibili a causa di un problema con lo strumento di misura. L’interazione tra NBI e plasma al JET é stata studiata tramite simulazioni predittive anche per scariche in idrogeno, partendo da scariche di riferimento in deuterio, con l’obbiettivo di studiare gli effetti che il cambiamento isotopico provoca sul plasma di JET. Studi sugli effetti isotopici sono stati effettuati anche per LHD, esperimento a configurazione elicoidale, dove si stanno preparando i futuri esperimenti in deuterio al posto degli usuali esperimenti in idrogeno. L’iniezione di particelle neutre é una delle opzioni come riscaldamento addizionale del plasma per il futuro reattore dimostrativo DEMO. Attualmente uno studio pre-concettuale di questo reattore é in corso a livello europeo. Simulazioni degli scenari di DEMO sono state effettuate sia per il progetto di un DEMO pulsato, sia per un DEMO a funzionamento stazionario. Il ruolo dell’NBI come riscaldamento principale e sistema per indurre la corrente di plasma é stato investigato tramite studi di sensibilitá, confronti con altri sistemi di riscaldamento e simulazioni delle fasi transitorie del plasma (accensione - ramp-up - e spegnimento - ramp-down - della scarica).
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Girardo, Jean-Baptiste. « Control of instabilities and turbulence by fast particles in fusion plasmas ». Palaiseau, Ecole polytechnique, 2015. http://www.theses.fr/2015EPXX0121.

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Chen, Li. « Fast pyrolysis of millimetric wood particles between 800°C and 1000°C ». Thesis, Lyon 1, 2009. http://www.theses.fr/2009LYO10258.

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Ces travaux de thèse s’intègrent au sein du projet Biocarb lancé par le Commissariat à l’Énergie Atomique dont l’objectif est de développer des procédés de production de carburants liquides ou gazeux à partir de gaz de synthèse riche en H2 et CO obtenu par gazéification de la biomasse lignocellulosique. L’objectif de cette étude est d’étudier le comportement de particules de biomasse millimétriques lors de la pyrolyse dans des conditions types de gazéifieurs industriels tels que les réacteurs à lit fluidisé ou à flux entraîné, qui fonctionnent pour des flux de chaleur élevés (105 – 106 W⋅m-2) et pour de hautes températures (>800°C). Tout d’abord, des expériences de pyrolyse sont menées à 800 et 950°C dans un four à chute de laboratoire sur des particules de bois entre 350 et 800 μm. Les résultats montrent que dans les conditions de l’étude, l’augmentation de la taille de la particule augmente seulement la durée de la pyrolyse mais ne modifie pas les rendements ou la composition du solide et du gaz au cours de la pyrolyse. Par ailleurs, des mesures basées sur la technique de PTV (Particle Tracking Velocimetry) sont réalisées à température ambiante pour caractériser la taille et la densité des particules de bois brut et de résidu, et valider une corrélation donnant le coefficient de traînée qui sert à calculer le temps de séjour des particules dans le réacteur. On constate à la fin de la pyrolyse une diminution de la densité comprise entre 70 et 80% ainsi qu’une diminution de la taille des particules entre 25 et 40%. Les résultats montrent également que la vitesse de glissement de la particule et l’évolution de ses propriétés doivent être prises en compte lors du calcul de sa vitesse. Enfin, à partir des résultats expérimentaux, un modèle unidimensionnel à coeur rétrécissant est développé pour décrire le comportement d’une particule de bois lors de sa pyrolyse. Le modèle est capable de prévoir l’évolution du rendement en solide, en gaz total et en goudrons au cours de la pyrolyse ainsi que la vitesse de glissement de la particule et son temps de séjour dans le réacteur.L’analyse de sensibilité du modèle montre que même pour des particules millimétriques, une connaissance précise de la chaleur de réaction associée à la pyrolyse, de la densité du bois et de la conductivité thermique du résidu solide est essentielle
The present work is part of a project of the French energy research centre Commissariat à l’Energie Atomique. The goal of the project is to develop processes of production of gaseous or liquid fuel from synthesis gas obtained by gasification of lignocellulosic biomass. The objective of the present work is to study the pyrolysis behaviour of millimetric biomass particles under the operating conditions encountered in fluidized bed or entrained flow gasifiers, namely high external heat flux (105 – 106 W⋅m-2) and high temperature (> 800°C). First, pyrolysis experiments are conducted at 800 and 950°C in a lab-scale drop tube reactor on wood particles between 350 and 800 μm. The results show that under the explored conditions, the increase of the particle size only increases the time required for pyrolysis but does not affect the product distribution during pyrolysis. Since in the pyrolysis experiments, the particle residence time cannot be directly measured, PTV (Particle Tracking Velocimetry) measurements are performed at room temperature to characterize the evolution of the particle size and density along pyrolysis and to validate a drag coefficient correlation for the particle residence time calculation. The optical measurements show that at the end of pyrolysis there is a decrease of particle density of 70 – 80% and of particle size of 25 – 40%. It is also proven that the particle slip velocity cannot be neglected and that the change of these particle properties must be taken into account for the calculation of the particle slip velocity and residence time. Finally, based on these experimental results, a 1D shrinking-core model is developed that is able to predict the solid/gas/tar yields and the residence time of a single particle along pyrolysis in the drop tube reactor. It is validated on both the pyrolysis and optical experiments. The model sensitivity analysis shows that even for millimetric particles, the accurate knowledge of the heat of pyrolysis, of the wood density and of the char thermal conductivity is essential
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Feher, Tamas Bela [Verfasser]. « Simulation of the interaction between Alfvén waves and fast particles / Tamas Bela Feher ». Greifswald : Universitätsbibliothek Greifswald, 2014. http://d-nb.info/1048536556/34.

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Müller, Matthias S. [Verfasser]. « Fast algorithms for the simulation of granular particles / Rechenzentrum, Universität Stuttgart... Matthias S. Müller ». Stuttgart : RUS [u.a.], 2001. http://d-nb.info/964089122/34.

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CORREA, DEISE A. C. « Estudo da fluencia do aco inoxidavel AISI-316 irradiado com neutrons rapidos e particulas alfa ». reponame:Repositório Institucional do IPEN, 1986. http://repositorio.ipen.br:8080/xmlui/handle/123456789/9886.

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IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
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Livres sur le sujet "Fast particles"

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Stefanovich, Remizovich Valeriĭ, et Ri͡a︡zanov Mikhail Ivanovich, dir. Collisions of fast charged particles in solids. New York : Gordon and Breach, 1985.

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Engenhart-Cabillic, Rita, et André Wambersie, dir. Fast Neutrons and High-LET Particles in Cancer Therapy. Berlin, Heidelberg : Springer Berlin Heidelberg, 1998. http://dx.doi.org/10.1007/978-3-642-78774-4.

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1953-, Engenhart R., et Wambersie A, dir. Fast neutrons and high-LET particles in cancer therapy. Berlin : Springer, 1998.

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Pauly, Hans. Atom, Molecule, and Cluster Beams II : Cluster Beams, Fast and Slow Beams, Accessory Equipment and Applications. Berlin, Heidelberg : Springer Berlin Heidelberg, 2000.

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Research Institute for Advanced Computer Science (U.S.), dir. A fast sorting algorithm for a hypersonic rarefied flow particle simulation on the connection machine. [Moffett Field, Calif.] : Research Institute for Advanced Computer Science, NASA Ames Research Center, 1989.

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Hansen, F. R. Possible Influence of Edge Density Fluctuations on the Proposed Fast Ion and Alpha Particle Diagnostic for Jet. Roskilde, Denmark : Riso National Laboratory, 1988.

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Gibson, W. C. Fast ion mass spectrometry and charged particle spectrography investigations of transverse ion acceleration and beam-plasma interactions. [Washington, DC : National Aeronautics and Space Administration, 1987.

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Zuxun, Sun, dir. Beijing International Symposium on Fast Neutron Physics : Beijing, China, 9-13 September 1991. Singapore : World Scientific, 1992.

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Office, General Accounting. Nuclear science : Fast Flux Test Facility on standby, awaiting DOE decision on future missions : fact sheet for the Chairman, Environment, Energy, and Natural Resources Subcommittee, Committee on Government Operations, House of Representatives. Washington, D.C : U.S. General Accounting Office, 1992.

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Giles, Roger. Design and development of a time of flight fast scattering spectrometer : A quantitative surface analysis technique and anew approach towards the experimental investigation of the surface particle interactions. Birmingham : Aston University. Department of Electronic Engineering and Applied Physics, 1995.

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Chapitres de livres sur le sujet "Fast particles"

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Harwit, Martin. « Photons and Fast Particles ». Dans Astrophysical Concepts, 159–89. New York, NY : Springer New York, 1988. http://dx.doi.org/10.1007/978-1-4757-2019-8_5.

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Harwit, Martin. « Photons and Fast Particles ». Dans Astrophysical Concepts, 149–82. New York, NY : Springer New York, 1998. http://dx.doi.org/10.1007/978-1-4757-2928-3_5.

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Somov, Boris V. « Fast Particles in Solar Flares ». Dans Astrophysics and Space Science Library, 439–57. New York, NY : Springer New York, 2013. http://dx.doi.org/10.1007/978-1-4614-4295-0_17.

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Beall, J. H. « Energy Loss Mechanisms for Fast Particles ». Dans Physical Processes in Hot Cosmic Plasmas, 341–55. Dordrecht : Springer Netherlands, 1990. http://dx.doi.org/10.1007/978-94-009-0545-0_20.

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Somov, Boris V. « Propagation of Fast Particles in Plasma ». Dans Astrophysics and Space Science Library, 59–85. New York, NY : Springer New York, 2012. http://dx.doi.org/10.1007/978-1-4614-4283-7_4.

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Cohen, L. « Complications of Fast Neutron Therapy ». Dans Fast Neutrons and High-LET Particles in Cancer Therapy, 156–69. Berlin, Heidelberg : Springer Berlin Heidelberg, 1998. http://dx.doi.org/10.1007/978-3-642-78774-4_10.

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Kurizki, Gershon, et J. K. McIver. « Quantum Theory of Fast-Charged Particles in Crystals ». Dans Relativistic Channeling, 177–84. Boston, MA : Springer US, 1987. http://dx.doi.org/10.1007/978-1-4757-6394-2_13.

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Belyakov, Vladimir Alekseevich. « Radiation of Fast Charged Particles in Regular Media ». Dans Partially Ordered Systems, 140–87. New York, NY : Springer New York, 1992. http://dx.doi.org/10.1007/978-1-4612-4396-0_5.

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Gurin, A. A., et A. S. Adamenko. « Registration of Fast Particles from the arget Explosion ». Dans Controlled Nucleosynthesis, 105–51. Dordrecht : Springer Netherlands, 2007. http://dx.doi.org/10.1007/978-1-4020-5874-5_6.

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Chen, Sheng. « A Fast Discrete Element Method for Adhesive Particles ». Dans Microparticle Dynamics in Electrostatic and Flow Fields, 17–50. Singapore : Springer Nature Singapore, 2023. http://dx.doi.org/10.1007/978-981-16-0843-8_2.

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Actes de conférences sur le sujet "Fast particles"

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Casalderrey, Jorge Solana, Edward V. Shuryak et Derek Teaney. « Hydrodynamic flow from fast particles ». Dans Correlations and Fluctuations in Relativistic Nuclear Collisions. Trieste, Italy : Sissa Medialab, 2007. http://dx.doi.org/10.22323/1.030.0022.

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Kenarsari, Saeed Danaei, et Yuan Zheng. « A Numerical Modeling of Fast Pyrolysis of Spherical Biomass Particles ». Dans ASME 2012 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/imece2012-87768.

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Fast pyrolysis is a thermal decomposition process of converting biomass to bio-oil, which takes place in the absence of the oxidizer. Computational fluid dynamics (CFD) models existing in the literature often neglect temperature gradients within the particles and this may have resulted in inaccuracy of the fast pyrolysis process model. In this paper a dynamic numerical model to simulate fast pyrolysis of spherical biomass particles that considers the temperature gradient inside the particle is developed. This model incorporates the conservation of energy equation, coupled with the chemical kinetics model and allows for the shrinkage of the biomass particle during fast pyrolysis. The impacts of external heat flux, particle size, and biomass feedstock on the pyrolysis characteristics have been explored in terms of products’ composition and conversion time. The predictions of the present model are compared and identified to be in good agreement with experimental data in the literature.
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Albergante, M., J. P. Graves, T. Dannert, A. Fasoli, F. Zonca, S. Briguglio, G. Vlad et al. « Interaction between fast particles and turbulence ». Dans THEORY OF FUSION PLASMAS. AIP, 2008. http://dx.doi.org/10.1063/1.3033707.

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Di Claudio, Elio D., Giovanni Jacovitti, Gianni Orlandi et Andrea Proietti. « Fast Classification of Dust Particles from Shadows ». Dans International Conference on Pattern Recognition Applications and Methods. SCITEPRESS - Science and and Technology Publications, 2015. http://dx.doi.org/10.5220/0005218802410247.

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Pueschel, M. J. « Transport of fast particles in turbulent fields ». Dans MHD AND ENERGETIC PARTICLES : 5th ITER International Summer School. American Institute of Physics, 2012. http://dx.doi.org/10.1063/1.4751637.

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Li, ZeRen, Guozhi Wang, Zuoyou Li, Feng Wang et Zhenxiong Luo. « In-line Fraunhofer holographic system for measuring particle distribution of fast-moving particles ». Dans IC02, sous la direction de Roger A. Lessard, George A. Lampropoulos et Gregory W. Schinn. SPIE, 2003. http://dx.doi.org/10.1117/12.474373.

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Quispe, Filomen Incahuanaco, et Afonso Paiva. « Counting Particles : a simple and fast surface reconstruction method for particle-based fluids ». Dans 2022 35th SIBGRAPI Conference on Graphics, Patterns and Images (SIBGRAPI). IEEE, 2022. http://dx.doi.org/10.1109/sibgrapi55357.2022.9991770.

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Cedelle, J., M. Vardelle, B. Pateyron, P. Fauchais, M. Fukumoto et I. Ohgitani. « Plasma-Sprayed Particles : Impact Imaging and Flattening Particle Thermal History ». Dans ITSC2005, sous la direction de E. Lugscheider. Verlag für Schweißen und verwandte Verfahren DVS-Verlag GmbH, 2005. http://dx.doi.org/10.31399/asm.cp.itsc2005p0656.

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Abstract In plasma spraying, the individual droplet behavior at impact is the fundamental element to understand the resulting coating microstructure. A new experimental set-up, developed in SPCTS laboratory (Limoges, F) with two fast shutter cameras (exposure time : 100 ns…1ms) allows visualisation at impact of a single particle plasma sprayed with a direct current (d.c) torch. A fast two color pyrometer enables to monitor particle temperature just prior to its impact, its flattening and its thermal history. Working in parallel with a free falling drop experiment, enables to obtain larger (about three orders of magnitude) time and dimension scale (realized in Advanced Joining Process Laboratory, Toyohashi, J). Each technique gives interesting and complementary results thanks to pyrometric signals and images. Results obtained with plasma sprayed particles allow studying the matter ejections generated on impact splashing .while both techniques allow following the flattening splashing. Calculation and comparison of quenching rates for millimetre sized drops on a stainless steel substrate give indications concerning the disk shaped splat formation.
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KOLYBASOV, V. M. « MOVING TRIANGLE SINGULARITIES AND POLARIZATION OF FAST PARTICLES ». Dans Proceedings of the Conference “Bologna 2000 : Structure of the Nucleus at the Dawn of the Century”. WORLD SCIENTIFIC, 2001. http://dx.doi.org/10.1142/9789812810922_0032.

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Giftson Joy, John Abish, et Robello Samuel. « Fast Drilling Optimizer for Drilling Automation ». Dans SPE Western Regional Meeting. SPE, 2021. http://dx.doi.org/10.2118/200881-ms.

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Abstract The rate of penetration (ROP) was optimized using a particle swarm optimization algorithm for real-time field data to reduce drilling time and increase efficiency. ROP is directly related to drilling costs and is a major factor in determining mechanical specific energy, which is often used to quantify drilling efficiency. Optimization of ROP can therefore help cut down costs associated with drilling. ROP values were chosen from real-time field data, accounting for weight on bit, bit rotation, flow rate variation along with bit wear. A random forest regressor was used to find correlations between the dependent parameters. The parameters were then optimized for the given constraints to find the optimal solution space. The boundary constraints for the ROP function were determined from the real-time data. The function parameters were optimized using a particle swarm optimization algorithm. This is a meta-heuristic model used to optimize an objective function for its maximum or minimum within given constraints. The optimization method makes use of a population of solution particles which act as the particle swarm. These particles move collectively in the given solution space controlled by a mathematical model based on their position and velocity. This model makes use of the best-known solution for each particle and the global best position of the system to guide the swarm towards the optimal solution. The function was optimized for each well, providing optimal ROP values during real-time drilling. A fast drilling optimizer is crucial to automate and streamline the drilling process. This simultaneous optimization of ROP based on real-time data can be implemented during the process thereby increasing the efficiency of drilling as well as reducing the required drilling time.
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Rapports d'organisations sur le sujet "Fast particles"

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Zachary, A. Resonant Alfven wave instabilities driven by streaming fast particles. Office of Scientific and Technical Information (OSTI), mai 1987. http://dx.doi.org/10.2172/6270850.

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Bichsel, Hans. Stopping power of fast charged particles in heavy elements. Gaithersburg, MD : National Institute of Standards and Technology, 1991. http://dx.doi.org/10.6028/nist.ir.4550.

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C.Z. Cheng, K. Hill, N.N. Gorelenkov, S. Bernabei et et al. Stability Properties of Toroidal Alfven Modes Driven by Fast Particles. Office of Scientific and Technical Information (OSTI), novembre 1999. http://dx.doi.org/10.2172/14762.

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Hajdu, J., et H. Chapman. Ultra-fast Coherent Diffraction Imaging of Single Particles, Clusters and Biomolecules. Office of Scientific and Technical Information (OSTI), septembre 2006. http://dx.doi.org/10.2172/900146.

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Candy, J., D. Borba, G. T. A. Huysmans, W. Kerner et H. L. Berk. Nonlinear interaction of fast particles with Alfven waves in toroidal plasmas. Office of Scientific and Technical Information (OSTI), décembre 1996. http://dx.doi.org/10.2172/468588.

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Shemyakin, A. Estimation of dilution of a Fast Faraday Cup response due to the finite particles speed. Office of Scientific and Technical Information (OSTI), décembre 2016. http://dx.doi.org/10.2172/1408323.

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Schlachter, A. S., J. W. Stearns et W. S. Cooper. A neutral-beam diagnostic for fast confined alpha particles in a burning plasma : Application on CIT (Compact Ignition Tokamak). Office of Scientific and Technical Information (OSTI), octobre 1987. http://dx.doi.org/10.2172/5706795.

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Cheng, C. Z., N. N. Gorelenkov et C. T. Hsu. Fast particle destabilization of TAE modes. Office of Scientific and Technical Information (OSTI), septembre 1995. http://dx.doi.org/10.2172/206585.

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D. Gates, N. Gorelenkov et and R.B. White. Ion Heating by Fast Particle Induced Alfvin Turbulence. Office of Scientific and Technical Information (OSTI), mai 2001. http://dx.doi.org/10.2172/786534.

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Enright, Douglas, Frank Losasso et Ronald Fedkiw. A Fast and Accurate Semi-Lagrangian Particle Level Set Method. Fort Belvoir, VA : Defense Technical Information Center, avril 2004. http://dx.doi.org/10.21236/ada479118.

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