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Journal articles on the topic 'Particle Energy'
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1
da Silva, Mariana Vale, Victor Ferreira, and Carlos Pinho. "Determination of biomass combustion rate in a domestic fixed bed boiler." AIMS Energy 9, no. 5 (2021): 1067–96. http://dx.doi.org/10.3934/energy.2021049.
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<abstract> <p>This manuscript presents an experimental study on the combustion rate of biomass briquettes or logs in a domestic boiler, by monitoring the time decay of its mass and the temperature of the flame inside the boiler. Assuming close to steady state conditions, two combustion models were studied: the constant particle density-burning model and the constant particle diameter-burning model. For each model, the evolution of the global combustion resistance with the decay of the particle diameter was analyzed, and it was possible to conclude that the burning occurred approximately with constant particle size and that the heterogeneous C to CO reaction takes place at the surface of the inner carbonaceous core. The high values obtained for the Sherwood number revealed that there were significant convective effects inside the furnace and compare well with a previously developed Sherwood number correlation for a packed bed of active particles.</p> </abstract>
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Franji?, Siniša. "In Shortly about Energy and Energy Sources." Advances in Politics and Economics 4, no. 4 (October 25, 2021): p1. http://dx.doi.org/10.22158/ape.v4n4p1.
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Energy is an effective force, a life activity, a determination. Energy in physics is the ability of a body or system to do some work; a quantity that characterizes the motion, rest, or position of a body, liquid, particle, or system of particles, and a quantity to describe field particles transmitted by natural forces and particle interactions. Energy appears in nature, technology and industry in various forms that are transformed into each other according to the principle of energy conservation: it cannot be spend or created, but only change its form. An energy source is any substance which serves as a raw material in the process of obtaining energy.
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Zhao, Lihao, Helge I. Andersson, and Jurriaan J. J. Gillissen. "Interphasial energy transfer and particle dissipation in particle-laden wall turbulence." Journal of Fluid Mechanics 715 (January 9, 2013): 32–59. http://dx.doi.org/10.1017/jfm.2012.492.
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AbstractTransfer of mechanical energy between solid spherical particles and a Newtonian carrier fluid has been explored in two-way coupled direct numerical simulations of turbulent channel flow. The inertial particles have been treated as individual point particles in a Lagrangian framework and their feedback on the fluid phase has been incorporated in the Navier–Stokes equations. At sufficiently large particle response times the Reynolds shear stress and the turbulence intensities in the spanwise and wall-normal directions were attenuated whereas the velocity fluctuations were augmented in the streamwise direction. The physical mechanisms involved in the particle–fluid interactions were analysed in detail, and it was observed that the fluid transferred energy to the particles in the core region of the channel whereas the fluid received kinetic energy from the particles in the wall region. A local imbalance in the work performed by the particles on the fluid and the work exerted by the fluid on the particles was observed. This imbalance gave rise to a particle-induced energy dissipation which represents a loss of mechanical energy from the fluid–particle suspension. An independent examination of the work associated with the different directional components of the Stokes force revealed that the dominating energy transfer was associated with the streamwise component. Both the mean and fluctuating parts of the Stokes force promoted streamwise fluctuations in the near-wall region. The kinetic energy associated with the cross-sectional velocity components was damped due to work done by the particles, and the energy was dissipated rather than recovered as particle kinetic energy. Componentwise scatter plots of the instantaneous velocity versus the instantaneous slip-velocity provided further insight into the energy transfer mechanisms, and the observed modulations of the flow field could thereby be explained.
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Hirosawa, Fumie, Tomohiro Iwasaki, and Masashi Iwata. "Particle Impact Energy Variation with the Size and Number of Particles in a Planetary Ball Mill." MATEC Web of Conferences 333 (2021): 02016. http://dx.doi.org/10.1051/matecconf/202133302016.
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To investigate the mechanical energy applying to the particles in a grinding process using a planetary ball mill, the impact energy of particles was estimated by simulating the behavior of the particles and grinding balls using the discrete element method (DEM) under different conditions of the size and number of particles, corresponding to their variations during milling. As the impact energy contributing to the particle breakage, we focused on the particle impact energy generated at particle-to-grinding ball/wall and particle-to-particle collisions. The particle size and the number of particles affected the level of particle impact energy at a single collision and the number of collisions of particles, respectively, resulting in an increase of the total impact energy of particles with decreasing particle size and increasing number of particles. The result suggests that milling conditions such as the size of grinding balls should be adjusted appropriately based on the variation of the size and number of particles so that the particles can receive large amounts of the impact energy during milling.
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Hirosawa, Fumie, Tomohiro Iwasaki, and Masashi Iwata. "Particle Impact Energy Variation with the Size and Number of Particles in a Planetary Ball Mill." MATEC Web of Conferences 333 (2021): 02016. http://dx.doi.org/10.1051/matecconf/202133302016.
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To investigate the mechanical energy applying to the particles in a grinding process using a planetary ball mill, the impact energy of particles was estimated by simulating the behavior of the particles and grinding balls using the discrete element method (DEM) under different conditions of the size and number of particles, corresponding to their variations during milling. As the impact energy contributing to the particle breakage, we focused on the particle impact energy generated at particle-to-grinding ball/wall and particle-to-particle collisions. The particle size and the number of particles affected the level of particle impact energy at a single collision and the number of collisions of particles, respectively, resulting in an increase of the total impact energy of particles with decreasing particle size and increasing number of particles. The result suggests that milling conditions such as the size of grinding balls should be adjusted appropriately based on the variation of the size and number of particles so that the particles can receive large amounts of the impact energy during milling.
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XU, YONGFU, and YIDONG WANG. "SIZE EFFECT ON SPECIFIC ENERGY DISTRIBUTION IN PARTICLE COMMINUTION." Fractals 25, no. 02 (April 2017): 1750016. http://dx.doi.org/10.1142/s0218348x17500165.
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A theoretical study is made to derive an energy distribution equation for the size reduction process from the fractal model for the particle comminution. Fractal model is employed as a valid measure of the self-similar size distribution of comminution daughter products. The tensile strength of particles varies with particle size in the manner of a power function law. The energy consumption for comminuting single particle is found to be proportional to the 5(D−3)/3rd order of the particle size, [Formula: see text] being the fractal dimension of particle comminution daughter. The Weibull statistics is applied to describe the relationship between the breakage probability and specific energy of particle comminution. A simple equation is derived for the breakage probability of particles in view of the dependence of fracture energy on particle size. The calculated exponents and Weibull coefficients are generally in conformity with published data for fracture of particles.
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Williams, Sarah G. W., and David J. Furbish. "Particle energy partitioning and transverse diffusion during rarefied travel on an experimental hillslope." Earth Surface Dynamics 9, no. 4 (July 14, 2021): 701–21. http://dx.doi.org/10.5194/esurf-9-701-2021.
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Abstract. Rarefied particle motions on rough hillslope surfaces are controlled by the balance between gravitational heating of particles due to conversion of potential to kinetic energy and frictional cooling of the particles due to collisions with the surface. Here we elaborate on how particle energy is partitioned between kinetic, rotational, and frictional forms during downslope travel using measurements of particle travel distances on a laboratory-scale hillslope, supplemented with high-speed imaging of drop–impact–rebound experiments. The drop–impact–rebound experiments indicate that particle shape has a dominant role in energy conversion during impact with a surface. Relative to spherical and natural rounded particles, angular particles give greater variability in rebound behavior, resulting in more effective conversion of translational to rotational energy. The effects of particle shape on energy conversion are especially pronounced on a sloping sand-roughened surface. Angular particles travel shorter distances downslope than rounded particles, though travel distance data for both groups are well fit by generalized Pareto distributions. Moreover, particle–surface collisions during downslope motion lead to a transverse random-walk behavior and transverse particle diffusion. Transverse spreading increases with surface slope as there is more available energy to be partitioned into the downslope or transverse directions during collision due to increased gravitational heating. Rounded particles exhibit greater transverse diffusion than angular particles, as less energy is lost during collision with the surface. Because the experimental surface is relatively smooth, this random-walk behavior represents a top-down control on the randomization of particle trajectories due to particle shape, which is in contrast to a bottom-up control on randomization of particle trajectories associated with motions over rough surfaces. Importantly, transverse particle diffusion during downslope motion may contribute to a cross-slope particle flux and likely contributes to topographic smoothing of irregular hillslope surfaces such as scree slopes.
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Dufner, D. C., S. Danczyk, and M. Wooldridge. "Characterization Of SiOx Smoke Particles by Electron Energy Loss Spectroscopy and Energy-Filtering Imaging." Microscopy and Microanalysis 5, S2 (August 1999): 638–39. http://dx.doi.org/10.1017/s1431927600016512.
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Combustion synthesis has led to many advances in materials science, in part via the synthesis of powders consisting of particles of nanometer dimensions. Particle morphology is a key concern regarding the powders produced, but also of comparable importance is particle composition. Electron energy loss spectroscopy (EELS) and energy-filtering imaging (EFI) can be used to interrogate the gas-phase combustion synthesis environment for elemental particle composition information. Once established, this diagnostic approach can be used to address control of particle composition and other issues associated with particle formation and growth in flames. The evolution of the particle morphology in a laboratory scale combustion synthesis facility can be examined by passing TEM grids directly through the combustion synthesis flame at various heights above the burner surface, as shown in Fig. la. For the current work, SiOx particle samples are obtained from a SilL/^/FL/Ar flame using a rapid probe insertion technique.
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Schneiders, Lennart, Konstantin Fröhlich, Matthias Meinke, and Wolfgang Schröder. "The decay of isotropic turbulence carrying non-spherical finite-size particles." Journal of Fluid Mechanics 875 (July 22, 2019): 520–42. http://dx.doi.org/10.1017/jfm.2019.516.
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Direct particle–fluid simulations of heavy spheres and ellipsoids interacting with decaying isotropic turbulence are conducted. This is the rigorous extension of the spherical particle analysis in Schneiders et al. (J. Fluid Mech., vol. 819, 2017, pp. 188–227) to $O(10^{4})$ non-spherical particles. To the best of the authors’ knowledge, this represents the first particle-resolved study on turbulence modulation by non-spherical particles of near-Kolmogorov-scale size. The modulation of the turbulent flow is precisely captured by explicitly resolving the stresses acting on the fluid–particle interfaces. The decay rates of the fluid and particle kinetic energy are found to increase with the particle aspect ratio. This is due to the particle-induced dissipation rate and the direct transfer of kinetic energy, both of which can be substantially larger than for spherical particles depending on the particle orientation. The extra dissipation rate resulting from the translational and rotational particle motion is quantified to detail the impact of the particles on the fluid kinetic energy budget and the influence of the particle shape. It is demonstrated that the previously derived analytical model for the particle-induced dissipation rate of smaller particles is valid for the present cases albeit these involve significant finite-size effects. This generic expression allows us to assess the impact of individual inertial particles on the local energy balance independent of the particle shape and to quantify the share of the rotational particle motion in the kinetic energy budget. To enable the examination of this mechanistic model in particle-resolved simulations, a method is proposed to reconstruct the so-called undisturbed fluid velocity and fluid rotation rate close to a particle. The accuracy and robustness of the scheme are corroborated via a parameter study. The subsequent discussion emphasizes the necessity to account for the orientation-dependent drag and torque in Lagrangian point-particle models, including corrections for finite particle Reynolds numbers, to reproduce the local and global energy balance of the multiphase system.
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Aleksandrin, S. Yu, A. M. Galper, L. A. Grishantzeva, S. V. Koldashov, L. V. Maslennikov, A. M. Murashov, P. Picozza, V. Sgrigna, and S. A. Voronov. "High-energy charged particle bursts in the near-Earth space as earthquake precursors." Annales Geophysicae 21, no. 2 (February 28, 2003): 597–602. http://dx.doi.org/10.5194/angeo-21-597-2003.
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Abstract. The experimental data on high-energy charged particle fluxes, obtained in various near-Earth space experiments (MIR orbital station, METEOR-3, GAMMA and SAMPEX satellites) were processed and analyzed with the goal to search for particle bursts. Particle bursts have been selected in every experiment considered. It was shown that the significant part of high-energy charged particle bursts correlates with seismic activity. Moreover, the particle bursts are observed several hours before strong earthquakes; L-shells of particle bursts and corresponding earthquakes are practically the same. Some features of a seismo-magnetosphere connection model, based on the interaction of electromagnetic emission of seismic origin and radiation belt particles, were considered. Key words. Ionospheric physics (energetic particles, trapped; energetic particles, precipitating; magnetosphere-ionosphere interactions)
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Ro, Chul-Un. "Quantitative energy-dispersive electron probe X-ray microanalysis of individual particles." Powder Diffraction 21, no. 2 (June 2006): 140–44. http://dx.doi.org/10.1154/1.2204068.
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An electron probe X-ray microanalysis (EPMA) technique using an energy-dispersive X-ray detector with an ultrathin window, designated low-Z particle EPM, has been developed. The low-Z particle EPMA allows the quantitative determination of concentrations of low-Z elements, such as C, N, and O, as well as higher-Z elements that can be analyzed by conventional energy-dispersive EPMA. The quantitative determination of low-Z elements (using full Monte Carlo simulations, from the electron impact to the X-ray detection) in individual environmental particles has improved the applicability of single-particle analysis, especially in atmospheric environmental aerosol research; many environmentally important atmospheric particles, e.g. sulfates, nitrates, ammonium, and carbonaceous particles, contain low-Z elements. The low-Z particle EPMA was applied to characterize loess soil particle samples of which the chemical compositions are well defined by the use of various bulk analytical methods. Chemical compositions of the loess samples obtained from the low-Z particle EPMA turn out to be close to those from bulk analyses. In addition, it is demonstrated that the technique can also be used to assess the heterogeneity of individual particles.
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Shklyar, D. R. "On the nature of particle energization via resonant wave-particle interaction in the inhomogeneous magnetospheric plasma." Annales Geophysicae 29, no. 6 (June 29, 2011): 1179–88. http://dx.doi.org/10.5194/angeo-29-1179-2011.
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Abstract. When a quasi-monochromatic wave propagating in an inhomogeneous magnetoplasma has sufficiently large amplitude, there exist phase-trapped resonant particles whose energy increases or decreases depending on the "sign" of inhomogeneity. The variation of energy density of such particles can greatly exceed the wave energy density which contradicts energy conservation under the prevalent assumption that the wave serves as the energy source or sink. We show that, in fact, the energy increase (or decrease) of phase-trapped particles is related to energy transfer from (to) phase untrapped particles, while the wave basically mediates the energization process. Virtual importance of this comprehension consists in setting proper quantitative constraints on attainable particle energy. The results have immediate applications to at least two fundamental problems in the magnetospheric physics, i.e. particle dynamics in the radiation belts and whistler-triggered emissions.
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Xiao, Wangqiang, Lina Jin, and Binqiang Chen. "Theoretical Analysis and Experimental Verification of Particle Damper-Based Energy Dissipation with Applications to Reduce Structural Vibration." Shock and Vibration 2015 (2015): 1–8. http://dx.doi.org/10.1155/2015/186356.
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Particle damping technology can greatly reduce vibration of equipment and structure through friction and inelastic collisions of particles. An energy dissipation model for particle damper has been presented based on the powder mechanics and the collision theory. The energy dissipation equations of friction and collision motion are developed for the particle damper. The rationality of energy dissipation model has been verified by the experiment and the distributions for the energy dissipation of particles versus acceleration are nonlinear. As the experiment process includes lots of factors of energy dissipation, such as the noise and the air resistance, the experimental value is about 7% more than the simulation value. The simulation model can provide an effective method for the design of particle damper. And the particle parameters for damper have been investigated. The results have shown that choosing an appropriate particle density, particle size, and particle filling rate determined based on the simulation model will provide the optimal damping effect for the practical application of particle damping technology.
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Zhang, Junlong, Yin Hu, Jie Jiang, and Hao Zan. "Damping Characteristics of Cantilever Beam with Obstacle Grid Particle Dampers." Machines 10, no. 11 (October 29, 2022): 989. http://dx.doi.org/10.3390/machines10110989.
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In order to understand the damping effect and energy dissipation mechanism of the obstacle grid particle dampers, we conduct experimental and simulated studies. In this paper, the obstacle grid particle dampers are applied to the cantilever beam structure. The effect of filling ratio, particle size, particle material and excitation amplitude of the obstacle grid particle damper on the vibration characteristics of the cantilever beam is studied experimentally and compared with the conventional particle damper for damping effect. A simulation model of the particle damper was developed and experimentally validated using the discrete element method. The experimental results show that the vibration acceleration response of the obstacle grid particle damper decreases by 10.4 dB compared with the conventional particle damper at 90% filling ratio. The obstacle grid particle damper increases the area of energy transfer between the external vibration energy and the particles. It makes the particles, which originally have almost no contribution to the energy dissipation, produce violent motion and participate in the energy dissipation process, thus effectively improving the damping performance of the particle dampers.
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Li, Zhonggang. "The Physical Nature of Velocity." Applied Physics Research 10, no. 6 (November 30, 2018): 15. http://dx.doi.org/10.5539/apr.v10n6p15.
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Matter and energy are made up of the same basic particles. Why, then, is there a significant difference between matter and energy? This is because their basic particle compositions differ. The basic particle is the basic unit of mass and energy. Mass and energy conservations are essentially basic particle conversions. The basic particle is a vector, moving at the maximum velocity of the universe; however, after a substance tangibly solidifies, this velocity becomes zero. The velocity of a moving object is, thus, the ratio between the basic particles contributing to energy and those contributing to mass, and the direction of its velocity is determined by the basic particle directions. Electrons, photons, neutrons, protons, neutrinos, and other microscopic particles consist of basic particles. The total mass of a moving body increases with increasing velocity. This added mass is composed of basic particles provided by an external system. As relativity is a mathematical model, its equations may satisfy mathematical principles even though some of them may not represent objective physical facts; instead, these may simply be mathematical solutions without physical meanings.
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Baktybekov, K. "PARTICLE SWARM OPTIMIZATION WITH INDIVIDUALLY BIASED PARTICLES FOR RELIABLE AND ROBUST MAXIMUM POWER POINT TRACKING UNDER PARTIAL SHADING CONDITIONS." Eurasian Physical Technical Journal 17, no. 2 (December 24, 2020): 128–37. http://dx.doi.org/10.31489/2020no2/128-137.
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Efficient power control techniques are an integral part of photovoltaic system design. One of the means of managing power delivery is regulating the duty cycle of the DC to DC converter by various algorithms to operate only at points where power is maximum power point. Search has to be done as fast as possible to minimize power loss, especially under dynamically changing irradiance. The challenge of the task is the nonlinear behavior of the PV system under partial shading conditions. Depending on the size and structure of the photovoltaic panels, PSC creates an immense amount of possible P-V curves with numerous local maximums - requiring an intelligent algorithm for determining the optimal operating point. Existing benchmark maximum power point tracking algorithms cannot handle multiple peaks, and in this paper, we offer an adaptation of particle swarm optimization for the specific task.
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Agarwal, Pulkit, Han Wei Ang, Zongjin Ong, Aik Hui Chan, and Choo Hiap Oh. "On Multiparticle Production in Very High Energy Scattering." EPJ Web of Conferences 240 (2020): 07001. http://dx.doi.org/10.1051/epjconf/202024007001.
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A phenomenological model of particle production and hadronisation in high energy collisions is formulated using Dirac fields in Yukawa-like interaction and the resulting stochastic equation is solved numerically. Different initial conditions are used to compare particle- particle (ψ ψ) and particle-antiparticle (ψ* ψ) interactions. It is shown that in this simplified view, there is a clear difference between the final multiplicity distributions resulting from the two initial conditions. To model the restricted phase space (limited pseudorapidity) measurements in experiment, a “loss” function is also proposed to account for the undetected particles close to the beam line.
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Blandford, R. D. "Particle Acceleration Mechanisms." International Astronomical Union Colloquium 142 (1994): 515–20. http://dx.doi.org/10.1017/s0252921100077757.
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AbstractHigh-energy particle acceleration is observed to proceed in a diverse variety of astrophysical sites ranging from the terrestrial aurorae to the most distant quasars. Particle acceleration is a fairly common channel for the release of large-scale kinetic, rotational, and magnetic energy. Physical mechanisms include electrostatic acceleration, stochastic processes and diffusive shock energization. Cosmic-ray energy spectra have shapes which reflect escape, collisional, and radiative losses. The overall acceleration efficiency is controlled by the low-energy particle injection which may, in turn, feed back into the energization. Recent observational developments, which illustrate these general principles and raise fresh questions, are briefly summarized.Subject heading: acceleration of particles
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Small, J. A., J. A. Armstrong, D. S. Bright, and B. B. Thorne. "The Analysis of Particles With Energy Dispersive X-Ray Spectroscopy (EDS)." Microscopy and Microanalysis 4, S2 (July 1998): 184–85. http://dx.doi.org/10.1017/s1431927600021048.
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The addition of the Si-Li detector to the electron probe, the scanning electron microscope, and more recently the transmission electron microscope (resulting in the analytical electron microscope) has made it possible to obtain elemental analysis on individual “particles” with dimensions less than 1 nm using EDS. Although some initial particle studies on micrometer-sized particles were done on the electron probe using wavelength dispersive spectrometers, WDS, the variability and complexity of many particle compositions coupled with the high currents necessary for WDS made elemental analysis of particles by WDS difficult at best. In addition, the use of multiple spectrometers, each with a different view of the particle and therefore different particle geometry as shown in Fig. 1, limited the quantitative capabilities of the technique. With the introduction of the Si-Li detector, there was only one spectrometer with a single geometry resulting in the development of various procedures for obtaining quantitative elemental analysis of the individual particles.
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Schneiders, Lennart, Matthias Meinke, and Wolfgang Schröder. "Direct particle–fluid simulation of Kolmogorov-length-scale size particles in decaying isotropic turbulence." Journal of Fluid Mechanics 819 (April 18, 2017): 188–227. http://dx.doi.org/10.1017/jfm.2017.171.
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The modulation of decaying isotropic turbulence by 45 000 spherical particles of Kolmogorov-length-scale size is studied using direct particle–fluid simulations, i.e. the flow field over each particle is fully resolved by direct numerical simulations of the conservation equations. A Cartesian cut-cell method is used by which the exchange of momentum and energy at the fluid–particle interfaces is strictly conserved. It is shown that the particles absorb energy from the large scales of the carrier flow while the small-scale turbulent motion is determined by the inertial particle dynamics. Whereas the viscous dissipation rate of the bulk flow is attenuated, the particles locally increase the level of dissipation due to the intense strain rate generated near the particle surfaces due to the crossing-trajectory effect. Analogously, the rotational motion of the particles decouples from the local fluid vorticity and strain-rate field at increasing particle inertia. The high level of dissipation is partially compensated by the transfer of momentum to the fluid via forces acting at the particle surfaces. The spectral analysis of the kinetic energy budget is supported by the average flow pattern about the particles showing a nearly universal strain-rate distribution. An analytical expression for the instantaneous rate of viscous dissipation induced by each particle is derived and subsequently verified numerically. Using this equation, the local balance of fluid kinetic energy around a particle of arbitrary shape can be precisely determined. It follows that two-way coupled point-particle models implicitly account for the particle-induced dissipation rate via the momentum-coupling terms; however, they disregard the actual length scales of the interaction. Finally, an analysis of the small-scale flow topology shows that the strength of vortex stretching in the bulk flow is mitigated due to the presence of the particles. This effect is associated with the energy conversion at small wavenumbers and the reduced level of dissipation at intermediate wavenumbers. Consequently, it damps the spectral flux of energy to the small scales.
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Petrov, E. V., I. V. Saikov, G. R. Saikova, and V. S. Trofimov. "Properties of the surface layer after high-energy treatment by powder particles." Izvestiya vuzov. Poroshkovaya metallurgiya i funktsional’nye pokrytiya, no. 1 (March 14, 2020): 29–35. http://dx.doi.org/10.17073/1997-308x-2020-29-35.
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Experiments were conducted on high-energy surface treatment of a structural steel substrate with a flow of tungsten, nickel, and titanium nitride powder particles. The impact pressure of the steel target and particles accelerated by explosion energy was estimated using the momentum conservation equation and the linear equation of the particle material shock adiabat. It was found that the impact pressure of the target and particles is 62 GPa for a tungsten particle, 48 GPa for a nickel particle, and 41 GPa for a titanium nitride particle. The heating temperature of particles during their collision with the steel target surface was calculated taking into account the conditions of mass and momentum conservation at the shock wave front. The maximum heating temperature of particles at the point of their collision with the substrate surface (at a particle velocity of 2000 m/s) is 1103 K for tungsten particles, 755 K for nickel particles, and 589 K for titanium nitride particles. It was shown that the steel target strength increases when it is subjected to high-energy treatment with a flow of particles. The maximum hardening of the steel target surface layer increases by 32–55 % compared to initial microhardness and is observed at a depth of 2–4 mm from the treatment surface. Then it decreases to the value of starting material microhardness (170 HV) at a distance of 15–20 mm from the treated surface.
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Ding, Tianxiang, Xuyan Hou, Man Li, Guangyu Cao, Jixuan Liu, Xianlin Zeng, and Zongquan Deng. "Investigation on Computing Method of Martian Dust Fluid Based on the Energy Dissipation Method." International Journal of Aerospace Engineering 2020 (May 23, 2020): 1–13. http://dx.doi.org/10.1155/2020/2370385.
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In this paper, an initiative Martian dust fluid simulating research based on the energy dissipation method was developed to simulate the deposition process of Martian dust fluid which was caused by surface adhesion between particles and Martian rovers. Firstly, an energy dissipation model of particles based on the Discrete Element Method (DEM) was established because of the characteristics of Martian dust particles such as tiny size and viscoelasticity. This model is based on the existing DMT model to analyze the collision deposition of dust fluid particles, including particle-spacecraft collision and particle-particle collision. Secondly, this paper analyzed the characteristics of particles after their first collision, then, established the stochastic model of critical wind speed for the particle deposition process. Finally, a series of simulations of the Martian dust fluid particle deposition process were done based on DEM-CFD. The results verified the accuracy of the energy dissipation model and the stochastic model, which could also verify the feasibility and effectiveness of the computing method of Martian dust fluid based on the DEM-CFD technology.
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Franceschini, Roberto. "Energy peaks: A high energy physics outlook." Modern Physics Letters A 32, no. 38 (December 14, 2017): 1730034. http://dx.doi.org/10.1142/s0217732317300348.
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Energy distributions of decay products carry information on the kinematics of the decay in ways that are at the same time straightforward and quite hidden. I will review these properties and discuss their early historical applications, as well as more recent ones in the context of (i) methods for the measurement of masses of new physics particle with semi-invisible decays, (ii) the characterization of Dark Matter particles produced at colliders, (iii) precision mass measurements of Standard Model particles, in particular of the top quark. Finally, I will give an outlook of further developments and applications of energy peak method for high energy physics at colliders and beyond.
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BOIVIN, MARC, OLIVIER SIMONIN, and KYLE D. SQUIRES. "Direct numerical simulation of turbulence modulation by particles in isotropic turbulence." Journal of Fluid Mechanics 375 (November 25, 1998): 235–63. http://dx.doi.org/10.1017/s0022112098002821.
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The modulation of isotropic turbulence by particles has been investigated using direct numerical simulation (DNS). The particular focus of the present work is on the class of dilute flows in which particle volume fractions and inter-particle collisions are negligible. Gravitational settling is also neglected and particle motion is assumed to be governed by drag with particle relaxation times ranging from the Kolmogorov scale to the Eulerian time scale of the turbulence and particle mass loadings up to 1. The velocity field was made statistically stationary by forcing the low wavenumbers of the flow. The calculations were performed using 963 collocation points and the Taylor-scale Reynolds number for the stationary flow was 62. The effect of particles on the turbulence was included in the Navier–Stokes equations using the point-force approximation in which 963 particles were used in the calculations. DNS results show that particles increasingly dissipate fluid kinetic energy with increased loading, with the reduction in kinetic energy being relatively independent of the particle relaxation time. Viscous dissipation in the fluid decreases with increased loading and is larger for particles with smaller relaxation times. Fluid energy spectra show that there is a non-uniform distortion of the turbulence with a relative increase in small-scale energy. The non-uniform distortion significantly affects the transport of the dissipation rate, with the production and destruction of dissipation exhibiting completely different behaviours. The spectrum of the fluid–particle energy exchange rate shows that the fluid drags particles at low wavenumbers while the converse is true at high wavenumbers for small particles. A spectral analysis shows that the increase of the high-wavenumber portion of the fluid energy spectrum can be attributed to transfer of the fluid–particle covariance by the fluid turbulence. This in turn explains the relative increase of small-scale energy caused by small particles observed in the present simulations as well as those of Squires & Eaton (1990) and Elghobashi & Truesdell (1993).
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Grib, A. A., and Yu V. Pavlov. "Black holes and high energy physics." International Journal of Modern Physics A 31, no. 02n03 (January 20, 2016): 1641016. http://dx.doi.org/10.1142/s0217751x16410165.
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Three mechanisms of getting high energies in particle collisions in the ergosphere of the rotating black holes are considered. The consequences of these mechanisms for observation of ultra high energy cosmic rays particles on the Earth as result of conversion of superheavy dark matter particles into ordinary particles are discussed.
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Burlakov, Victor M., and Alain Goriely. "Reverse Coarsening and the Control of Particle Size Distribution through Surfactant." Applied Sciences 10, no. 15 (August 3, 2020): 5359. http://dx.doi.org/10.3390/app10155359.
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The minimization of surface area, as a result of the minimization of (positive) surface energy, is a well-known driving force behind the spontaneous broadening of (nano) particle size distribution. We show that surfactant molecules binding to particle surfaces effectively decrease the surface energy and may change its sign. In this case, contrary to the expected broadening behavior, a minimum of free energy is achieved at the maximum surface area for all particles, i.e., when the particles are identical. Numerical simulations based on the classical Lifshitz–Slyozov–Wagner theory with surfactant-induced surface energy renormalization confirm the collapse of the particle size distribution. As the particle size evolution is much slower than particle nucleation and growth, the manipulation of surface energy with in-situ replacement of surfactant molecules provides a method for controlling particle size distribution with great potential for creating mono-disperse nanoparticles, a key goal of nanotechnology.
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Greene, G. L. "Low-Energy Particle Physics." Science 256, no. 5065 (June 26, 1992): 1836. http://dx.doi.org/10.1126/science.256.5065.1836.
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Gan, Deqing, Feng Gao, Yunpeng Zhang, Jinxia Zhang, Fusheng Niu, and Ze Gan. "Effects of the Shape and Size of Irregular Particles on Specific Breakage Energy under Drop Weight Impact." Shock and Vibration 2019 (June 4, 2019): 1–14. http://dx.doi.org/10.1155/2019/2318571.
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Particle shape and size are main factors influencing particle breakage. Single-particle breakage tests were conducted on irregular magnetite ore using modified drop weight impact equipment to analyze the effect of shape and size on specific breakage energy. A method to measure the effective breakage energy is presented. Ore particles with different sphericities and different sizes were broken into several fragments with differing impact energies in the tests. Experimental studies indicate that the shape of particles significantly influences the impact loading mode and breakage progress; the specific breakage energy has an obvious relationship with the sphericity and the initial size. The specific breakage energy decreases with larger initial loading area. The particle needs less specific breakage energy if the shape or placement state is more conducive to tensile fracture. There is an increase in specific breakage energy corresponding to an increase in particle sphericity with fixed initial size range. With the increase in the initial size of the particle, the specific breakage energy decreases with fixed sphericity range, which presents a power function with the exponent −0.5. The comprehensive relationship between specific breakage energy, particle sphericity, and initial size was established, showing that the input power of the crushing machinery and the optimization of crushing technology should be performed with consideration of the influence of particle shape and initial size to reduce specific energy consumption and improve energy efficiency.
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Trofymenko, Sergii, Igor Kyryllin, and Oleksandr Shchus. "On the Impact Parameter Dependence of the Ionization Energy Loss of Fast Negatively Charged Particles in an Oriented Crystal." 4, no. 4 (December 10, 2021): 68–75. http://dx.doi.org/10.26565/2312-4334-2021-4-07.
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When a fast charged particle passes through matter, it loses some of its energy to the excitation and ionization of atoms. This energy loss is called ionization energy loss. In rather thin layers of matter, the value of such energy loss is stochastic. It is distributed in accordance with the law, which was first received by L.D. Landau. In amorphous substances, such a distribution (or spectrum), known as the Landau distribution, has a single maximum that corresponds to the most probable value of particle energy loss. When a particle moves in crystal in a planar channeling mode, the probability of close collisions of the particle with atoms decreases (for a positive particle charge) or increases (for a negative charge), which leads to a change in the most probable energy loss compared to an amorphous target. It has recently been shown that during planar channeling of negatively charged particles in a crystal, the distribution of ionization energy loss of the particles is much wider than in the amorphous target. In this case, this distribution can be two-humped, if we neglect the incoherent scattering of charged particles on the thermal oscillations of the crystal atoms and the electronic subsystem of the crystal. This paper explains the reason for this distribution of ionization energy loss of particles. The ionization energy loss distribution of high-energy negatively charged particles which move in the planar channeling mode in a silicon crystal are studied with the use of numerical simulation. The dependence of this distribution on the impact parameter of the particles with respect to atomic planes is considered. The dependence of the most probable ionization energy loss of particles on the impact parameter is found. It is shown that, for a large group of particles, the most probable ionization energy loss during planar channeling in a crystal is lower than in an amorphous target.
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Thein, Min Htike, and Kian Meng Lim. "Estimation of Acoustic Energy and Performance Characterization of Acoustic Concentrator." Applied Mechanics and Materials 842 (June 2016): 217–27. http://dx.doi.org/10.4028/www.scientific.net/amm.842.217.
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Among many methods of particle concentration in liquid, acoustic concentrator uses ultrasonic standing wave to concentrate microparticles in liquid. In order to determine its performance on particle concentration, estimation of acoustic energy density inside the concentrator is important since energy density is the main contributing factor in calculating the primary acoustic radiation force acting on the particles. The balance between the primary radiation force and hydrodynamic force acting on the particles inside the acoustic concentrator determine the performance of the acoustic concentrator. Therefore, this study focuses on the measurement of acoustic energy density inside the h-shaped acoustic concentrator and characterization of performance of the concentrator. First, energy density is estimated by curve-fitting the experimental particle position in the ultrasonic field with one-dimensional theoretical position. Second, two-dimensional acoustic and hydrodynamic fields are determined using two-dimensional simulation model in COMSOL Multiphysics. Integrating the governing equation for particle motion in the balance of acoustic and hydrodynamic forces result in the particle trajectory and it is compared with the experimental observation. The results would provide deeper insight into the operation of acoustic concentrator and the detailed phenomenon of particle motions inside the concentrator.
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Orozco, Luisa Fernanda, Jean-Yves Delenne, Philippe Sornay, and Farhang Radjai. "Effect of particle shape on particle breakage inside rotating cylinders." EPJ Web of Conferences 249 (2021): 07002. http://dx.doi.org/10.1051/epjconf/202124907002.
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We study the influence of particle shape on the evolution of particle breakage process taking place inside rotating cylinders. Extensive particle dynamics simulations taking into account the dynamics of the granular flow, particle breakage, and polygonal particle shapes were carried out. We find that the rate of particle breakage is faster in samples composed of initially rounder particles. The analysis of the active flowing layer thickness suggests that for samples composed of rounder particles a relatively lower dilatancy and higher connectivity lead to a less curved free surface profile. As a result, rounder particles rolling down the free surface have a higher mobility and thus higher velocities. In consequence, the faster breakage observed for rounder initial particles is due to the larger particles kinetic energy at the toe of the flow.
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Zaslavskii, Oleg B. "New Scenarios of High-Energy Particle Collisions Near Wormholes." Universe 6, no. 12 (November 30, 2020): 227. http://dx.doi.org/10.3390/universe6120227.
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We suggest two new scenarios of high-energy particle collisions in the background of a wormhole. In scenario 1, the novelty consists of the fact that the effect does not require two particles coming from different mouths. Instead, all such scenarios of high energy collisions develop, when an experimenter sends particles towards a wormhole from the same side of the throat. For static wormholes, this approach leads to indefinitely large energy in the center of mass. For rotating wormholes, it makes possible the super-Penrose process (unbounded energies measured at infinity). In scenario 2, one of colliding particles oscillates near the wormhole throat from the very beginning. In this sense, scenario 2 is intermediate between the standard one and scenario 1 since the particle under discussion does not come from infinity at all.
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Peng, Guili, Xianguo Tuo, Huailiang Li, and Rui Shi. "Advanced Direct Digital Synthesis Generator Design for Transuranic Nuclide Alpha Spectrometry Pulses." Mathematical Problems in Engineering 2021 (February 22, 2021): 1–9. http://dx.doi.org/10.1155/2021/6665362.
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Alpha energy spectrum measurement has been employed in the nuclear waste disposal of transuranic nuclides (such as 239Pu and 241Am), supervision, and disposal process. The alpha spectrum is made up of alpha particles, which have a fast-moving helium nucleus and an energy of 4–8 MeV with weak penetration ability. Removing alpha particles from radioactive nuclides is an important scientific issue. In this study, a transuranic nuclide alpha particle pulse generator that produces simulated alpha particle pulses similar to real particles was designed. Field programmable gate array (FPGA) was adopted as its core chip and we obtained the digital pulse waveform using software tracing points while simulating real alpha particles by random numbers. Accordingly, the alpha energy spectrum of a radioactive source 241Am was obtained using a passivated ion-implanted planar silicon (PIPS) detector. Afterward, the alpha particle was extracted from the energy spectrum and was then compared to the alpha particle pulse of the two methods, deriving a result. Here, both groupings of particle pulse waveforms were found to be very similar, and the periodic error of the particle was observed to be less than 1%. Furthermore, the amplitude and time interval of the particle were apparently similar to the actual spectrometry pulse.
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Pontalier, Q., J. Loiseau, S. Goroshin, F. Zhang, and D. L. Frost. "Blast enhancement from metalized explosives." Shock Waves 31, no. 3 (April 2021): 203–30. http://dx.doi.org/10.1007/s00193-021-00994-z.
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AbstractExperiments are carried out to determine the effects of particle size and mass loading on the free-field blast wave from spherical, constant volume metalized explosive charges. The charges are comprised of gelled nitromethane with uniformly embedded aluminum, magnesium, or glass particles. Particle sizes are varied over an order of magnitude with particle mass fractions up to 50%. Peak blast overpressures are directly measured within the fireball with piezoelectric pressure gauges and outside the fireball are inferred by tracking the velocity of the blast wave and using the Rankine–Hugoniot relation. With the addition of inert particles, the peak blast overpressure is initially mitigated, but then recovers in the far field. For charges with reactive particles, the particles react promptly with oxidizers in the detonation products and release energy as early as within the first few hundred microseconds in all cases. The particle energy release enhances the peak blast overpressures in the far field by up to twice the values for a constant volume charge of the baseline homogenous explosive. By plotting the peak blast overpressure decay as a function of energy-scaled distance, it is inferred that at least half of the particle energy release contributes to the blast overpressure in the far field of higher mass loadings, and nearly all of the particle energy for a particle mass fraction of 10%. For aluminum, the blast augmentation is not a systematic function of particle size. This observation implies that conventional models for particle combustion that depend on particle surface area are not appropriate for describing the rapid aluminum reaction that occurs in the extreme conditions within the detonation products, which influences the blast wave propagation.
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Lu, Yingchao, Fan Guo, Patrick Kilian, Hui Li, Chengkun Huang, and Edison Liang. "Studying particle acceleration from driven magnetic reconnection at the termination shock of a relativistic striped wind using particle-in-cell simulations." EPJ Web of Conferences 235 (2020): 07003. http://dx.doi.org/10.1051/epjconf/202023507003.
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A rotating pulsar creates a surrounding pulsar wind nebula (PWN) by steadily releasing an energetic wind into the interior of the expanding shockwave of supernova remnant or interstellar medium. At the termination shock of a PWN, the Poynting-flux- dominated relativistic striped wind is compressed. Magnetic reconnection is driven by the compression and converts magnetic energy into particle kinetic energy and accelerating particles to high energies. We carrying out particle-in-cell (PIC) simulations to study the shock structure as well as the energy conversion and particle acceleration mechanism. By analyzing particle trajectories, we find that many particles are accelerated by Fermi-type mechanism. The maximum energy for electrons and positrons can reach hundreds of TeV.
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Furbish, David Jon, Sarah G. W. Williams, Danica L. Roth, Tyler H. Doane, and Joshua J. Roering. "Rarefied particle motions on hillslopes – Part 2: Analysis." Earth Surface Dynamics 9, no. 3 (June 16, 2021): 577–613. http://dx.doi.org/10.5194/esurf-9-577-2021.
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Abstract. We examine a theoretical formulation of the probabilistic physics of rarefied particle motions and deposition on rough hillslope surfaces using measurements of particle travel distances obtained from laboratory and field-based experiments, supplemented with high-speed imaging and audio recordings that highlight effects of particle–surface collisions. The formulation, presented in a companion paper (Furbish et al., 2021a), is based on a description of the kinetic energy balance of a cohort of particles treated as a rarefied granular gas, as well as a description of particle deposition that depends on the energy state of the particles. Both laboratory and field-based measurements are consistent with a generalized Pareto distribution of travel distances and predicted variations in behavior associated with the balance between gravitational heating due to conversion of potential to kinetic energy and frictional cooling due to particle–surface collisions. For a given particle size and shape these behaviors vary from a bounded distribution representing rapid thermal collapse with small slopes or large surface roughness, to an exponential distribution representing approximately isothermal conditions, to a heavy-tailed distribution representing net heating of particles with large slopes. The transition to a heavy-tailed distribution likely involves an increasing conversion of translational to rotational kinetic energy leading to larger travel distances with decreasing effectiveness of collisional friction. This energy conversion is strongly influenced by particle shape, although the analysis points to the need for further clarity concerning how particle size and shape in concert with surface roughness influence the extraction of particle energy and the likelihood of deposition.
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Xia, Q., and V. Zharkova. "Particle acceleration in coalescent and squashed magnetic islands." Astronomy & Astrophysics 635 (March 2020): A116. http://dx.doi.org/10.1051/0004-6361/201936420.
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Aims. Particles are known to have efficient acceleration in reconnecting current sheets with multiple magnetic islands that are formed during a reconnection process. Using the test-particle approach, the recent investigation of particle dynamics in 3D magnetic islands, or current sheets with multiple X- and O-null points revealed that the particle energy gains are higher in squashed magnetic islands than in coalescent ones. However, this approach did not factor in the ambient plasma feedback to the presence of accelerated particles, which affects their distributions within the acceleration region. Methods. In the current paper, we use the particle-in-cell (PIC) approach to investigate further particle acceleration in 3D Harris-type reconnecting current sheets with coalescent (merging) and squashed (contracting) magnetic islands with different magnetic field topologies, ambient densities ranging between 108 − 1012 m−3, proton-to-electron mass ratios, and island aspect ratios. Results. In current sheets with single or multiple X-nullpoints, accelerated particles of opposite charges are separated and ejected into the opposite semiplanes from the current sheet midplane, generating a strong polarisation electric field across a current sheet. Particles of the same charge form two populations: transit and bounced particles, each with very different energy and asymmetric pitch-angle distributions, which can be distinguished from observations. In some cases, the difference in energy gains by transit and bounced particles leads to turbulence generated by Buneman instability. In magnetic island topology, the different reconnection electric fields in squashed and coalescent islands impose different particle drift motions. This makes particle acceleration more efficient in squashed magnetic islands than in coalescent ones. The spectral indices of electron energy spectra are ∼ − 4.2 for coalescent and ∼ − 4.0 for squashed islands, which are lower than reported from the test-particle approach. The particles accelerated in magnetic islands are found trapped in the midplane of squashed islands, and shifted as clouds towards the X-nullpoints in coalescent ones. Conclusions. In reconnecting current sheets with multiple X- and O-nullpoints, particles are found accelerated on a much shorter spatial scale and gaining higher energies than near a single X-nullpoint. The distinct density and pitch-angle distributions of particles with high and low energy detected with the PIC approach can help to distinguish the observational features of accelerated particles.
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Artemyev, A. V., L. M. Zelenyi, H. V. Malova, G. Zimbardo, and D. Delcourt. "Acceleration and transport of ions in turbulent current sheets: formation of non-maxwelian energy distribution." Nonlinear Processes in Geophysics 16, no. 6 (November 4, 2009): 631–39. http://dx.doi.org/10.5194/npg-16-631-2009.
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Abstract. The paper is devoted to particle acceleration in turbulent current sheet (CS). Our results show that the mechanism of CS particle interaction with electromagnetic turbulence can explain the formation of power law energy distributions. We study the ratio between adiabatic acceleration of particles in electric field in the presence of stationary turbulence and acceleration due to electric field in the case of dynamic turbulence. The correlation between average energy gained by particles and average particle residence time in the vicinity of the neutral sheet is discussed. It is also demonstrated that particle velocity distributions formed by particle-turbulence interaction are similar in essence to the ones observed near the far reconnection region in the Earth's magnetotail.
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Hu, Lei, and Hongwu Zhu. "Study on energy transition of dense particulate flow in a horizontal agitator." Journal of Physics: Conference Series 2383, no. 1 (December 1, 2022): 012069. http://dx.doi.org/10.1088/1742-6596/2383/1/012069.
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Hammer mill cuttings cleaner is an efficient low-temperature drying cuttings equipment. In order to investigate the main components of energy dissipation and the flow characteristics of granular flow in grinding systems. The energy dissipation model of dense particle flow is established by numerical simulation and validated by macroscopic experiment. The results show that the particle flow mainly moves in a circle along the wall of cylindrical vessel. The main parts of energy dissipation are sliding friction consumption of particle, the inelastic collision between particles and sliding friction between particles and container; the input energy is a linear function of particle filling rate. The flat blade can provide higher efficiency at the same operational conditions. The study lays a theoretical foundation for the industrial application of Thermal-mechanical cuttings cleaner of drill cuttings and provides a reference for the optimization of blade configuration.
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ØIEN, ALF H. "Interaction energy and closest approach of moving charged particles on a plasma and neutral gas background." Journal of Plasma Physics 78, no. 1 (July 11, 2011): 11–19. http://dx.doi.org/10.1017/s0022377811000286.
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AbstractElectric interaction between two negatively charged particles of different sizes on a mixed background of positive, negative, and neutral particles is complex and has relevance both to dusty plasmas and to transports in ionized fluids in general. We consider particularly effects during interaction that particle velocity and neutrals in the background may have on the well-known “dressing” and electric shielding that is due to the charged part of the background and how the interaction energy is modified because of this. Without such effects earlier works show the interaction becomes attractive when the distance between the two particles is a bit larger than the Debye length. We use a model where one of the two interacting particles has a radius much larger than the Debye length and the other a radius shorter than the Debye length. Then, the complex interaction may be more easily determined for particle separation up to a few Debye lengths. We consider the larger particle as stationary while the smaller may move. We find quite simple analytic expressions for the dressed particle interaction energy over the whole range of speed of the incoming smaller particle, assumed coming head on the larger particle, and the whole range of neutral particle densities. We also derive a distance of closest approach of small and large particles for all such parameter values. This distance is important for excluded volume estimations for moving small charged particles in media populated by large charged particles on a background as described above, and hence, important for determining the speed of flow of the smaller particles through such media.
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Rieger, Frank M., and Peter Duffy. "Particle Acceleration in Relativistic Shearing Flows: Energy Spectrum." Astrophysical Journal 933, no. 2 (July 1, 2022): 149. http://dx.doi.org/10.3847/1538-4357/ac729c.
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Abstract We consider the acceleration of charged particles in relativistic shearing flows, with Lorentz factor up to Γ0 ∼ 20. We present numerical solutions to the particle transport equation and compare these with results from analytical calculations. We show that in the highly relativistic limit the particle energy spectrum that results from acceleration approaches a power law, N ( E ) ∝ E − q ˜ , with a universal value q ˜ = ( 1 + α ) for the slope of this power law, where α parameterizes the power-law momentum dependence of the particle mean free path. At mildly relativistic flow speeds, the energy spectrum becomes softer and sensitive to the underlying flow profile. We explore different flow examples, including Gaussian and power-law-type velocity profiles, showing that the latter yield comparatively harder spectra, producing q ˜ ≃ 2 for Γ0 ≃ 3 and Kolmogorov turbulence. We provide a comparison with a simplified leaky-box approach and derive an approximate relation for estimating the spectral index as a function of the maximum shear flow speed. These results are of relevance for jetted, high-energy astrophysical sources such as active galactic nuclei, since shear acceleration is a promising mechanism for the acceleration of charged particles to relativistic energies and is likely to contribute to the high-energy radiation observed.
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Sahoo, Raghunath, Aditya Nath Mishra, Nirbhay K. Behera, and Basanta K. Nandi. "Charged Particle, Photon Multiplicity, and Transverse Energy Production in High-Energy Heavy-Ion Collisions." Advances in High Energy Physics 2015 (2015): 1–30. http://dx.doi.org/10.1155/2015/612390.
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We review the charged particle and photon multiplicities and transverse energy production in heavy-ion collisions starting from few GeV to TeV energies. The experimental results of pseudorapidity distribution of charged particles and photons at different collision energies and centralities are discussed. We also discuss the hypothesis of limiting fragmentation and expansion dynamics using the Landau hydrodynamics and the underlying physics. Meanwhile, we present the estimation of initial energy density multiplied with formation time as a function of different collision energies and centralities. In the end, the transverse energy per charged particle in connection with the chemical freeze-out criteria is discussed. We invoke various models and phenomenological arguments to interpret and characterize the fireball created in heavy-ion collisions. This review overall provides a scope to understand the heavy-ion collision data and a possible formation of a deconfined phase of partons via the global observables like charged particles, photons, and the transverse energy measurement.
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Torsti, J., E. Valtonen, L. Kocharov, M. Lumme, T. Eronen, M. Louhola, E. Riihonen, et al. "Energetic particle investigation using the ERNE instrument." Annales Geophysicae 14, no. 5 (May 31, 1996): 497–502. http://dx.doi.org/10.1007/s00585-996-0497-5.
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Abstract. During solar flares and coronal mass ejections, nuclei and electrons accelerated to high energies are injected into interplanetary space. These accelerated particles can be detected at the SOHO satellite by the ERNE instrument. From the data produced by the instrument, it is possible to identify the particles and to calculate their energy and direction of propagation. Depending on variable coronal/interplanetary conditions, different kinds of effects on the energetic particle transport can be predicted. The problems of interest include, for example, the effects of particle properties (mass, charge, energy, and propagation direction) on the particle transport, the particle energy changes in the transport process, and the effects the energetic particles have on the solar-wind plasma. The evolution of the distribution function of the energetic particles can be measured with ERNE to a better accuracy than ever before. This gives us the opportunity to contribute significantly to the modeling of interplanetary transport and acceleration. Once the acceleration/transport bias has been removed, the acceleration-site abundance of elements and their isotopes can be studied in detail and compared with spectroscopic observations.
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Körpınar, Talat, and Ridvan Cem Demirkol. "A new construction on the energy of space curves in unit vector fields in Minkowski space E₂⁴." Boletim da Sociedade Paranaense de Matemática 39, no. 2 (January 1, 2021): 105–20. http://dx.doi.org/10.5269/bspm.39288.
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In this paper, we firstly introduce kinematics properties of a moving particle lying in Minkowski space E₂⁴. We assume that particles corresponds to different type of space curves such that they are characterized by Frenet frame equations. Guided by these, we present geometrical understanding of an energy and pseudo angle on the particle in each Frenet vector fields depending on the particle corresponds to a spacelike, timelike or lightlike curve in E₂⁴. Then we also determine the bending elastic energy functional for the same particle in E₂⁴ by assuming the particle has a bending feature of elastica. Finally, we prove that bending energy formula can be represented by the energy on the particle in each Frenet vector field.
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Jassim, Esam. "Particle Entrainment and Deposition Scenario in Sublayer Region of Variable Area Conduit." E3S Web of Conferences 162 (2020): 03006. http://dx.doi.org/10.1051/e3sconf/202016203006.
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The study presents the particle deposition and aggregation phenomena by introducing new parameter called Particle Deposition Number PDN, defined as the ratio of the particle instantaneous velocity to its capturing value. The particle capture or rebound fate will decide from knowing such number. The study employed new scheme of particle deposition in the sublayer region which includes balancing of four forces. Moreover, the bouncing model is also considered for particle fate decision. The study examines the variation of particle velocity at varying area tube and the critical velocity in which particle will tend to stick if its velocity is lower than the threshold limit. The results show that threshold velocity is exponentially decreased with the increment in the particle size. Capturing of particles is shown to be enhanced as the conduit converges due to increasing in the PDN. The analysis of the deposition also investigates the impact of the particle size on the PDN. At low flow velocity, the NDP has V-shaped trend as particle size increases. However, veering toward constant PDN value has occurred as the flow velocity augmented. Finally, small sized particles experience rebound due to the prevailing of the particle impact energy over the adhesion energy before impacting with the surface. The dissipation in the particle energy during impaction causes large sized particle to loose greater amount of energy compare to small sized one, resulting in domination of the adhesion part, which leads to deposition on the surface.
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Yi-Fang, Chang. "Final Simplest Model of Smallest Particles and Possibly Developed Directions of Particle Physics." Physical Science & Biophysics Journal 5, no. 2 (2021): 1–12. http://dx.doi.org/10.23880/psbj-16000196.
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First, so far the high energy experiments in the past sixty years have shown that the smallest mass fermions are proton, electron, neutrino and photon, which form the simplest model of particles. These fermions seem to be inseparable truth “atoms” (elements), because further experiments derive particles with bigger mass. They correspond to four interactions, and are also only stable particles. Next, the final simplest theory is based on leptons (e- e ν ) and nucleons (p-n) or (u-d) in quark model with SU(2) symmetry and corresponding Yang-Mills field. Other particles and quark-lepton are their excited states. Their spectrum is mass formula and symmetric lifetime formula. Some applications are discussed. Further, the simplest interactions and unification of weak-strong interactions by QCD are discussed. We research opposite continuous separable models. Finally, we propose some possibly developed directions of particle physics, for example, violation of basic principles, in particular, the uncertainty principle, and precision and systematization of the simplest model, etc.
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Vreman, A. W. "Particle-resolved direct numerical simulation of homogeneous isotropic turbulence modified by small fixed spheres." Journal of Fluid Mechanics 796 (April 28, 2016): 40–85. http://dx.doi.org/10.1017/jfm.2016.228.
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A statistically stationary homogeneous isotropic turbulent flow modified by 64 small fixed non-Stokesian spherical particles is considered. The particle diameter is approximately twice the Kolmogorov length scale, while the particle volume fraction is 0.001. The Taylor Reynolds number of the corresponding unladen flow is 32. The particle-laden flow has been obtained by a direct numerical simulation based on a discretization of the incompressible Navier–Stokes equations on 64 spherical grids overset on a Cartesian grid. The global (space- and time-averaged) turbulence kinetic energy is attenuated by approximately 9 %, which is less than expected. The turbulence dissipation rate on the surfaces of the particles is enhanced by two orders of magnitude. More than 5 % of the total dissipation occurs in only 0.1 % of the flow domain. The budget of the turbulence kinetic energy has been computed, as a function of the distance to the nearest particle centre. The budget illustrates how energy relatively far away from particles is transported towards the surfaces of the particles, where it is dissipated by the (locally enhanced) turbulence dissipation rate. The energy flux towards the particles is dominated by turbulent transport relatively far away from particles, by viscous diffusion very close to the particles, and by pressure diffusion in a significant region in between. The skewness and flatness factors of the pressure, velocity and velocity gradient have also been computed. The global flatness factor of the longitudinal velocity gradient, which characterizes the intermittency of small scales, is enhanced by a factor of six. In addition, several point-particle simulations based on the Schiller–Naumann drag correlation have been performed. A posteriori tests of the point-particle simulations, comparisons in which the particle-resolved results are regarded as the standard, show that, in this case, the point-particle model captures both the turbulence attenuation and the fraction of the turbulence dissipation rate due to particles reasonably well, provided the (arbitrary) size of the fluid volume over which each particle force is distributed is suitably chosen.
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CALZADO, L., H. YEPEZ-MARTINEZ, and H. A. CALDERON. "MODELING THE MICROMECHANICAL STATE OF γ′-PRECIPITATES IN Ni-BASED SUPERALLOYS." International Journal of Modern Physics B 21, no. 21 (August 20, 2007): 3733–44. http://dx.doi.org/10.1142/s0217979207037612.
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A simple model for describing the mechanical state associated with γ′-particles in Ni – Al superalloys is presented. The model is based on the properties of the anisotropic elastic Green function. The strain and stress fields produced by a single cubic particle are described. The self-energy for parallelepiped γ′-particles is calculated, finding the cubic geometry as the energetically most favorable particle shape. The anisotropy interaction between γ′-particles is investigated. The computed results are further examined considering the interaction energy between constituting elements of the particles. The configurational force acting on a γ′-particle during a creep test is analyzed.
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Majeed, Bushra, and Mubasher Jamil. "Dynamics and center of mass energy of colliding particles around black hole in f(R) gravity." International Journal of Modern Physics D 26, no. 05 (April 2017): 1741017. http://dx.doi.org/10.1142/s0218271817410176.
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We have investigated the dynamics of particles in the vicinity of a static spherically symmetric black hole in [Formula: see text] gravity. Using the Euler Lagrange method, the dynamical equations of a neutral particle are obtained. Assuming that the particle is initially moving in the innermost stable circular orbit (IMSCO), we have calculated its escape velocity, after a collision with some other particle. The conditions for the escape of colliding particles are discussed. The effective potential and the trajectories of the escaping particles are studied graphically.
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Furbish, David Jon, Joshua J. Roering, Tyler H. Doane, Danica L. Roth, Sarah G. W. Williams, and Angel M. Abbott. "Rarefied particle motions on hillslopes – Part 1: Theory." Earth Surface Dynamics 9, no. 3 (June 16, 2021): 539–76. http://dx.doi.org/10.5194/esurf-9-539-2021.
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Abstract. We describe the probabilistic physics of rarefied particle motions and deposition on rough hillslope surfaces. The particle energy balance involves gravitational heating with conversion of potential to kinetic energy, frictional cooling associated with particle–surface collisions, and an apparent heating associated with preferential deposition of low-energy particles. Deposition probabilistically occurs with frictional cooling in relation to the distribution of particle energy states whose spatial evolution is described by a Fokker–Planck equation. The Kirkby number Ki – defined as the ratio of gravitational heating to frictional cooling – sets the basic deposition behavior and the form of the probability distribution fr(r) of particle travel distances r, a generalized Pareto distribution. The shape and scale parameters of the distribution are well-defined mechanically. For isothermal conditions where frictional cooling matches gravitational heating plus the apparent heating due to deposition, the distribution fr(r) is exponential. With non-isothermal conditions and small Ki this distribution is bounded and represents rapid thermal collapse. With increasing Ki the distribution fr(r) becomes heavy-tailed and represents net particle heating. It may possess a finite mean and finite variance, or the mean and variance may be undefined with sufficiently large Ki. The formulation provides key elements of the entrainment forms of the particle flux and the Exner equation, and it clarifies the mechanisms of particle-size sorting on large talus and scree slopes. Namely, with conversion of translational to rotational kinetic energy, large spinning particles are less likely to be stopped by collisional friction than are small or angular particles for the same surface roughness.