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1
Akatsuka, Maiko. "A Feasibility Study on a Monitoring for Seagrass beds Using Environmental DNA." ARPHA Conference Abstracts 4 (March 4, 2021): e65262. https://doi.org/10.3897/aca.4.e65262.
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In order to protect marine resources listed in the SDGs, it is important to conduct surveys to understand the current status and transition of aquatic species such as fish and seagrass. However, the area and frequency of surveys are often limited due to the lack of manpower and cost. Environmental DNA (eDNA) analysis is a method to obtain information of aquatic species in the sea or rivers. The aquatic species are identified by analyzing DNA contained in the sampled water. The eDNA analysis can be utilized as a new and efficient method for investigating aquatic species.The author is developing a monitoring method for seagrass beds using eDNA.Seagrasses are sessile organisms and don't move like a fish, the areas where eDNA is generated are fixed. Therefore, eDNA path in a seagrass beds area can be predicted by flow prediction simulation. The monitoring carries out in the path of eDNA released from seagrass.When there is a correlation between the amount of DNA and the amount of biomass, it is possible to gain knowledge of the amount of biomass from sampling water in the path of eDNA. For example, the changes in the amount of biomass due to growth and withering of seagrass beds can be studied by observing the changes in the amount of DNA. The purpose of this study is to examine the feasibility of the monitoring method using experiments, field surveys and numerical simulations for eDNA.The water tank experiments for 15 months, suggested that the amount of seagrass eDNA is related to the seasonal changes in the biomass of seagrass, which has been grown in the water tank. In the conducted four field surveys, the amount of eDNA tended to be high during times of spring with high amounts of seagrasses. In addition, the decomposition process of eDNA were examined by laboratory experiments using sea water. As a result, seagrass DNA contained in the sampling sea water was degraded and undetected within around 5 days. This result suggests that information obtained from the sampling water reflects biological information within a few days. These results suggest the possibility to estimate the changes in biomass by using eDNA in the sea.And, in the field surveys, it was shown that the amount of eDNA is small, so we have recognized that increasing the amount of sampling water and improvement of the DNA analysis method is an issue.This monitoring method is feasible when the collected eDNA is related to a specific seagrass bed. The feasibility of the method was considered using numerical simulation.In the numerical simulation, a particle tracking method using 10 types of simple bay shapes was used to trace the path of eDNA regarded as a particle.When the eDNA started from multiple positions, it was searched for position where the point where DNA starts and arrives is uniquely determined.As a result, at some observation points, the particles that departed from a specific position was observed without being mixed with particles departing from other starting positions, and this was true for all bay types. In addition, the same tendency could be obtained in calculations using the bathymetry of Ago bay, in Mie prefecture.These suggests that it may be possible to monitor seagrass beds by performing fixed-point observations according to the seagrass beds distribution and bay flow.Since few cases in the sea were conducted, the authors intend to continue the survey for the upcoming years and continue the study under various conditions including numerical analysis.
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Parker, Jason T., та Simo A. Mäkiharju. "Experimentally validated x-ray image simulations of 50 μm x-ray PIV tracer particles". Measurement Science and Technology 33, № 5 (2022): 055301. http://dx.doi.org/10.1088/1361-6501/ac4c0d.
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Abstract We evaluate Beer–Lambert (BL) ray-tracing and Monte Carlo N-Particle (MCNP) photon tracking simulations for prediction and comparison of x-ray imaging system performance. These simulation tools can aid the methodical design of laboratory-scale x-ray particle image velocimetry (XPIV) experiments and tracer particles by predicting image quality. Particle image signal-to-noise ratio (SNR) is used as the metric of system performance. Simulated and experiment data of hollow, silver-coated, glass sphere tracer particles (AGSF-33) are compared. As predicted by the simulations, the AGSF-33 particles are visible with a SNR greater than unity in 100 ms exposure time images, demonstrating their potential as x-ray PIV or particle tracking velocimetry (XPTV) tracers. The BL approach predicts the image contrast, is computationally inexpensive, and enables the exploration of a vast parameter space for system design. MCNP simulations, on the other hand, predict experiment images slightly more accurately, but are more than an order of magnitude more computationally expensive than BL simulations. For most practical XPIV system design applications, the higher computational expense of MCNP is likely not justified by the modest accuracy improvement compared to BL.
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Yin, Chungen. "A novel accurate model for tracking irregular particles: Development, implementation, and impact on biomass combustors." Bioresource Technology 429 (April 18, 2025): 132519. https://doi.org/10.1016/j.biortech.2025.132519.
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Multiphase flows with irregular solid particles are ubiquitous in engineering applications, where particle rotation critically influences dynamics, mixing, phase interactions, and chemical reactions. Conventional particle-tracking models often neglect rotation, focusing solely on translational motion. Recent advances in drag, lift, and torque coefficients for irregular particles, derived from particle-resolved direct numerical simulations, underscore the need of models that account for both translational and rotational motion. This study bridges this gap by developing a novel model that accurately couples these motions. Leveraging drag, lift, and torque coefficients derived from thousands of particle-resolved simulations and an advanced analytical discretization scheme, this model ensures high accuracy, numerical robustness and broad applicability. The model's capabilities are demonstrated through computational fluid dynamics (CFD) simulations of a natural gas/biomass co-fired burner, with biomass particles represented as prolate ellipsoids. The results reveal that biomass particles predominantly rotate around their minor axes, with rotation intensifying as particle size decreases. For equi-volume diameters decreasing from 16.5 mm to 165 µm, peak angular velocities around minor axes surge from approximately 4 to 6,600 rad/s, while those around major axes remain 1–2 orders of magnitude lower, rising from 0.03 to 71 rad/s. Compared to conventional models, this model provides unprecedented insights into particle rotation and significantly improves simulation outcomes without compromising computational efficiency. Notably, it extends particle residence times (∼20 % longer in the 10-meter-long burner chamber), enhances mixing and lateral particle dispersion, and intensifies phase interactions, making it a valuable tool for simulating particle-laden multiphase flows in engineering applications. © 2025 The Author(s)
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Chang, L., G. Bourianoff, B. Cole, and S. Machida. "A Parallel Implementation of Particle Tracking with Space Charge Effects on an Intel iPSC/860." Scientific Programming 2, no. 3 (1993): 37–47. http://dx.doi.org/10.1155/1993/397679.
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Particle-tracking simulation is one of the scientific applications that is well suited to parallel computations. At the Superconducting Super Collider, it has been theoretically and empirically demonstrated that particle tracking on a designed lattice can achieve very high parallel efficiency on a MIMD Intel iPSC/860 machine. The key to such success is the realization that the particles can be tracked independently without considering their interaction. The perfectly parallel nature of particle tracking is broken if the interaction effects between particles are included. The space charge introduces an electromagnetic force that will affect the motion of tracked particles in three-dimensional (3-D) space. For accurate modeling of the beam dynamics with space charge effects, one needs to solve 3-D Maxwell field equations, usually by a particle-in-cell (PIC) algorithm. This will require each particle to communicate with its neighbor grids to compute the momentum changes at each time step. It is expected that the 3-D PIC method will degrade parallel efficiency of particle-tracking implementation on any parallel computer. In this paper, we describe an efficient scheme for implementing particle tracking with space charge effects on an INTEL iPSC/860 machine. Experimental results show that a parallel efficiency of 75% can be obtained.
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Du, Sichun, and Qing Deng. "Unscented Particle Filter Algorithm Based on Divide-and-Conquer Sampling for Target Tracking." Sensors 21, no. 6 (2021): 2236. http://dx.doi.org/10.3390/s21062236.
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Unscented particle filter (UPF) struggles to completely cover the target state space when handling the maneuvering target tracing problem, and the tracking performance can be affected by the low sample diversity and algorithm redundancy. In order to solve this problem, the method of divide-and-conquer sampling is applied to the UPF tracking algorithm. By decomposing the state space, the descending dimension processing of the target maneuver is realized. When dealing with the maneuvering target, particles are sampled separately in each subspace, which directly prevents particles from degeneracy. Experiments and a comparative analysis were carried out to comprehensively analyze the performance of the divide-and-conquer sampling unscented particle filter (DCS-UPF). The simulation result demonstrates that the proposed algorithm can improve the diversity of particles and obtain higher tracking accuracy in less time than the particle swarm algorithm and intelligent adaptive filtering algorithm. This algorithm can be used in complex maneuvering conditions.
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Leenaarts, Jorrit. "Tracing the evolution of radiation-MHD simulations of solar and stellar atmospheres in the Lagrangian frame." Astronomy & Astrophysics 616 (August 2018): A136. http://dx.doi.org/10.1051/0004-6361/201833176.
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Context. Radiation magnetohydrodynamics (radiation-MHD) simulations have become a standard tool for investigating the physics of solar and stellar atmospheres. Aims. The aim of this paper is to present a method that allows the efficient and accurate analysis of flows in such simulations in the Lagrangian frame. Methods. This paper presents a method that allows the construction of pathlines given a seed point that can be chosen freely at any location and at any time during the simulation where the simulation state is stored. The method is based on passive tracer particles. Through injection of particles in expanding regions the occurrence of particle-free volumes is avoided, even in the case of strongly compressive flows. Results. The method was implemented in the solar and stellar atmosphere simulation code Bifrost. It is efficient and accurate. As examples I present an analysis of a gas parcel in the convection zone and a particle in the solar transition region.
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LAVEZZO, V., A. SOLDATI, S. GERASHCHENKO, Z. WARHAFT, and L. R. COLLINS. "On the role of gravity and shear on inertial particle accelerations in near-wall turbulence." Journal of Fluid Mechanics 658 (June 15, 2010): 229–46. http://dx.doi.org/10.1017/s0022112010001655.
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Recent experiments in a turbulent boundary layer by Gerashchenko et al. (J. Fluid Mech., vol. 617, 2008, pp. 255–281) showed that the variance of inertial particle accelerations in the near-wall region increased with increasing particle inertia, contrary to the trend found in homogeneous and isotropic turbulence. This behaviour was attributed to the non-trivial interaction of the inertial particles with both the mean shear and gravity. To investigate this issue, we perform direct numerical simulations of channel flow with suspended inertial particles that are tracked in the Lagrangian frame of reference. Three simulations have been carried out considering (i) fluid particles, (ii) inertial particles with gravity and (iii) inertial particles without gravity. For each set of simulations, three particle response times were examined, corresponding to particle Stokes numbers (in wall units) of 0.9, 1.8 and 11.8. Mean and r.m.s. profiles of particle acceleration computed in the simulation are in qualitative (and in several cases quantitative) agreement with the experimental results, supporting the assumptions made in the simulations. Furthermore, by comparing results from simulations with and without gravity, we are able to isolate and quantify the significant effect of gravitational settling on the phenomenon.
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Perin, Rayhaan, Katie Cole, Michael R. van Heerden, et al. "On the Ability of Positron Emission Particle Tracking (PEPT) to Track Turbulent Flow Paths with Monte Carlo Simulations in GATE." Applied Sciences 13, no. 11 (2023): 6690. http://dx.doi.org/10.3390/app13116690.
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Positron emission particle tracking (PEPT) has offered important insights into the internal dynamics of multiphase flows. High precision and frequency measurements of the location of the tracer particle are required to resolve individual eddies at the millimetre scale or smaller. To explore the potential of PEPT to perform these measurements, a model was developed of the Siemens ECAT “EXACT3D” HR++ positron emission tomography (PET) scanner at the PEPT Cape Town facility in South Africa with the software Geant4 Application for Tomographic Emission (GATE) and was used to generate Lagrangian tracks from simulations of moving tracer particles. The model was validated with measurements from both experiment and simulation and was extended to two virtual scenarios inspired by turbulent flows. The location data from the simulation accurately captured linear portions of an oscillating path up to high speeds of 25 m s−1; however, tracking tended to undercut the turning points due to the high tracer acceleration. For a particle moving on a spiral path of decreasing radius, the location data tracked the path above a radius of 2.0 mm with an uncertainty equivalent to the radius of the tracer particle, 300 μm. Improvements to the measurement are required to track sub-millimetre flow structures, such as the application of PET scanners with higher spatial resolution and upgrades to the sampling processes used in location algorithms.
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Zhang, Lieping, Jinghua Nie, Shenglan Zhang, Yanlin Yu, Yong Liang, and Zuqiong Zhang. "Research on the Particle Filter Single-Station Target Tracking Algorithm Based on Particle Number Optimization." Journal of Electrical and Computer Engineering 2021 (September 4, 2021): 1–8. http://dx.doi.org/10.1155/2021/2838971.
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Given that the tracking accuracy and real-time performance of the particle filter (PF) target tracking algorithm are greatly affected by the number of sampled particles, a PF target tracking algorithm based on particle number optimization under the single-station environment was proposed in this study. First, a single-station target tracking model was established, and the corresponding PF algorithm was designed. Next, a tracking simulation experiment was carried out on the PF target tracking algorithm under different numbers of particles with the root mean square error (RMSE) and filtering time as the evaluation indexes. On this basis, the optimal number of particles, which could meet the accuracy and real-time performance requirements, was determined and taken as the number of particles of the proposed algorithm. The MATLAB simulation results revealed that compared with the unscented Kalman filter (UKF), the single-station PF target tracking algorithm based on particle number optimization not only was of high tracking accuracy but also could meet the real-time performance requirement.
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Heus, Thijs, Gertjan van Dijk, Harm J. J. Jonker, and Harry E. A. Van den Akker. "Mixing in Shallow Cumulus Clouds Studied by Lagrangian Particle Tracking." Journal of the Atmospheric Sciences 65, no. 8 (2008): 2581–97. http://dx.doi.org/10.1175/2008jas2572.1.
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Abstract Mixing between shallow cumulus clouds and their environment is studied using large-eddy simulations. The origin of in-cloud air is studied by two distinct methods: 1) by analyzing conserved variable mixing diagrams (Paluch diagrams) and 2) by tracing back cloud-air parcels represented by massless Lagrangian particles that follow the flow. The obtained Paluch diagrams are found to be similar to many results in the literature, but the source of entrained air found by particle tracking deviates from the source inferred from the Paluch analysis. Whereas the classical Paluch analysis seems to provide some evidence for cloud-top mixing, particle tracking shows that virtually all mixing occurs laterally. Particle trajectories averaged over the entire cloud ensemble also clearly indicate the absence of significant cloud-top mixing in shallow cumulus clouds.
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Hu, Shijie, Hongjun Li, Liying Zhang, and Yuzhen Xu. "Cold Spray Process for Co-Deposition of Copper and Aluminum Particles." Coatings 13, no. 11 (2023): 1953. http://dx.doi.org/10.3390/coatings13111953.
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Mixed-particle spraying has been applied to various aspects of industrial cold spraying for a long time. Due to the complexity of mixed-particle simulations, most studies only consider dozens of particles when considering particle collisions. This paper combines computational fluid dynamics and a discrete element method to analyze the entire trajectories of mixed particles. With simulations involving over one hundred thousand particles, we accurately tracked the three-dimensional positions and velocities of each particle, effectively visualizing their journey from feeder to substrate. By comparing the particles’ velocities to their critical velocities, we could directly assess the deposition efficiency, achieving a comprehensive and accurate simulation of the complete cold spray process. The numerical model was validated using a multi-experimental analysis. The particle distribution and deposition area from the numerical model matched well with the experimental data. It was found that the mutual collision of copper and aluminum particles increased the number of copper particles, surpassing the critical velocity in the mixed powder by 24.2%. When copper particles and aluminum particles collided, the displacement of aluminum particles was more than three times that of copper particles in the direction perpendicular to the jet. This collision caused the aluminum particles to be more dispersed.
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Mohd Yunos, Mohd Amirul Syafiq, Mark Dennis Anak Usang, Hanafi Ithnin, Siti Aslina Hussain, Hamdan Mohamed Yusoff, and Susan Sipaun. "Reconstruction Algorithm of Calibration Map for RPT Techniques in Quadrilateral Bubble Column Reactor Using MCNPX Code." European Journal of Engineering Research and Science 3, no. 1 (2018): 20. http://dx.doi.org/10.24018/ejers.2018.3.1.583.
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Radioactive Particle Tracking (RPT) is non-invasive evaluation technique capable of visualising and tracking the motion of the identified phase in bubble column reactor. The single radioactive particle emits γ-ray, and its movement in the column is tracked with the aid of arrays radiation detectors. In this study, Monte Carlo approach was programmed to reconstruct the particle tracer position so-called calibration map. The iterative reconstruction algorithms is used to generate and calculate the 2600 coordinates of calibration map from the number of photon counts from the ten NaI scintillation detectors. To validate the simulation precision, a spiral trajectory of radioactive particle inside the bubble column region consist of 84 grid point locations of the particle were applied. Calibration algorithm was developed for radioactive isotopes Au-198 and Sc-46 particle position verification and determination of statistical uncertainty from the introduction of a various number of primary photon emission. The result of the studies proved that higher number of particles used in the algorithm for position reconstruction gives more accuracy and we found that the Sc-46 obtain more accurate calculation and shows low statistical level than Au-198 particle. The outcome of this simulation based on random sampling from Monte Carlo N-Particle Extended (MCNPX) demonstrated that the calibration map could successfully be implemented in RPT technique to observe the dynamic movement of radioactive particle which represents the tracked media in the quadrilateral bubble column.
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Mohd Yunos, Mohd Amirul Syafiq, Mark Dennis Anak Usang, Hanafi Ithnin, Siti Aslina Hussain, Hamdan Mohamed Yusoff, and Susan Sipaun. "Reconstruction Algorithm of Calibration Map for RPT Techniques in Quadrilateral Bubble Column Reactor Using MCNPX Code." European Journal of Engineering and Technology Research 3, no. 1 (2018): 20–27. http://dx.doi.org/10.24018/ejeng.2018.3.1.583.
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Radioactive Particle Tracking (RPT) is non-invasive evaluation technique capable of visualising and tracking the motion of the identified phase in bubble column reactor. The single radioactive particle emits ?-ray, and its movement in the column is tracked with the aid of arrays radiation detectors. In this study, Monte Carlo approach was programmed to reconstruct the particle tracer position so-called calibration map. The iterative reconstruction algorithms is used to generate and calculate the 2600 coordinates of calibration map from the number of photon counts from the ten NaI scintillation detectors. To validate the simulation precision, a spiral trajectory of radioactive particle inside the bubble column region consist of 84 grid point locations of the particle were applied. Calibration algorithm was developed for radioactive isotopes Au-198 and Sc-46 particle position verification and determination of statistical uncertainty from the introduction of a various number of primary photon emission. The result of the studies proved that higher number of particles used in the algorithm for position reconstruction gives more accuracy and we found that the Sc-46 obtain more accurate calculation and shows low statistical level than Au-198 particle. The outcome of this simulation based on random sampling from Monte Carlo N-Particle Extended (MCNPX) demonstrated that the calibration map could successfully be implemented in RPT technique to observe the dynamic movement of radioactive particle which represents the tracked media in the quadrilateral bubble column.
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Hu, Liangquan, Zhiqiang Dong, Cheng Peng, and Lian-Ping Wang. "Direct Numerical Simulation of Sediment Transport in Turbulent Open Channel Flow Using the Lattice Boltzmann Method." Fluids 6, no. 6 (2021): 217. http://dx.doi.org/10.3390/fluids6060217.
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The lattice Boltzmann method is employed to conduct direct numerical simulations of turbulent open channel flows with the presence of finite-size spherical sediment particles. The uniform particles have a diameter of approximately 18 wall units and a density of ρp=2.65ρf, where ρp and ρf are the particle and fluid densities, respectively. Three low particle volume fractions ϕ=0.11%, 0.22%, and 0.44% are used to investigate the particle-turbulence interactions. Simulation results indicate that particles are found to result in a more isotropic distribution of fluid turbulent kinetic energy (TKE) among different velocity components, and a more homogeneous distribution of the fluid TKE in the wall-normal direction. Particles tend to accumulate in the near-wall region due to the settling effect and they preferentially reside in low-speed streaks. The vertical particle volume fraction profiles are self-similar when normalized by the total particle volume fractions. Moreover, several typical transport modes of the sediment particles, such as resuspension, saltation, and rolling, are captured by tracking the trajectories of particles. Finally, the vertical profiles of particle concentration are shown to be consistent with a kinetic model.
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Alnahit, Ali O., Nigel Berkeley Kaye, and Abdul A. Khan. "Understanding the Influence of the Buoyancy Sign on Buoyancy-Driven Particle Clouds." Fluids 9, no. 5 (2024): 101. http://dx.doi.org/10.3390/fluids9050101.
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A numerical model was developed to investigate the behavior of round buoyancy-driven particle clouds in a quiescent ambient. The model was validated by comparing model simulations with prior experimental and numerical results and then applied the model to examine the difference between releases of positively and negatively buoyant particles. The particle cloud model used the entrainment assumption while approximating the flow field induced by the cloud as a Hill’s spherical vortex. The motion of individual particles was resolved using a particle tracking equation that considered the forces acting on them and the induced velocity field. The simulation results showed that clouds with the same initial buoyancy magnitude and particle Reynolds number behaved differently depending on whether the particles were more dense or less dense than the ambient fluid. This was found even for very low initial buoyancy releases, suggesting that the sign of the buoyancy is always important and that, therefore, the Boussinesq assumption is never fully appropriate for such flows.
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Onderik, Juraj, Michal Chládek, and Roman Ďurikovič. "Animating multiple interacting miscible and immiscible fluids based on particle simulation." Journal of Applied Mathematics, Statistics and Informatics 9, no. 2 (2013): 73–86. http://dx.doi.org/10.2478/jamsi-2013-0014.
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Abstract We present a particle-based approach for animating multiple interacting liquids that can handle number of immiscible fluids as well as number of miscible fluids in our simulation framework. We solve the usual problem of robust interface tracking, between immiscible fluids, by reconstructing the zero level set of our novel composite implicit function, see Fig. 1 left and center. It’s recurrent formulation handles directly interfaces between any number of liquids including the free surfaces. We model the miscible fluids by tracking concentrations of dissolved materials in the vicinity of each particle. Flick’s law is applied for the Laplacian-based diffusion of concentrations, see Fig. 1 right. Particle sedimentation is achieved by directional advection along the settling velocity. The diffusion-advection equation is discretized by particles using the Lagrangian formulation. The proposed improvements can be easily implemented into the common Smoothed Particle Hydrodynamics (SPH) simulations framework
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Dolanský, Jindřich, Zdeněk Chára, Pavel Vlasák, and Bohuš Kysela. "Lattice Boltzmann method used to simulate particle motion in a conduit." Journal of Hydrology and Hydromechanics 65, no. 2 (2017): 105–13. http://dx.doi.org/10.1515/johh-2017-0008.
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AbstractA three-dimensional numerical simulation of particle motion in a pipe with a rough bed is presented. The simulation based on the Lattice Boltzmann Method (LBM) employs the hybrid diffuse bounce-back approach to model moving boundaries. The bed of the pipe is formed by stationary spherical particles of the same size as the moving particles. Particle movements are induced by gravitational and hydrodynamic forces. To evaluate the hydrodynamic forces, the Momentum Exchange Algorithm is used. The LBM unified computational frame makes it possible to simulate both the particle motion and the fluid flow and to study mutual interactions of the carrier liquid flow and particles and the particle–bed and particle–particle collisions. The trajectories of simulated and experimental particles are compared. The Particle Tracking method is used to track particle motion. The correctness of the applied approach is assessed.
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Reji, RV, and S. Anil Lal. "A new direct simulation Monte Carlo implementation for more efficient simulation of hypersonic flow over arbitrarily shaped bodies using dynamic cells." Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 231, no. 1 (2016): 82–97. http://dx.doi.org/10.1177/0954410016675901.
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Methods are reported for less computationally expensive and more accurate implementations of the direct simulation Monte Carlo (DSMC) method for the simulation of high speed gas flows over arbitrarily shaped bodies. A new particle-tracking algorithm with a saving of computational time of up to 10% is reported in which tracking of particles is done with the help of big triangles having vertices lying on the boundary curves. An algorithm has been developed to generate DSMC cells for collision and sampling that contain a prescribed number of molecules. This algorithm is able to generate over 90% cells having the optimum number of seven or eight molecules for simulating collisions. Sampling for macroscopic properties is done on dynamic cells that contain a number of particles varying spatially as a function of the local number density. A criterion for finding the number of particles in sampling cells is presented. This criterion has been found to result in accurate and fast simulation of two-dimensional hypersonic flows of argon over a wedge, and argon and nitrogen over a circular cylinder.
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Chen, Zhimin, Mengchu Tian, Yuming Bo, and Xiaodong Ling. "Infrared small target detection and tracking algorithm based on new closed-loop control particle filter." Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 233, no. 4 (2018): 1435–56. http://dx.doi.org/10.1177/0954410017753445.
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The problem of particle impoverishment could be always found in standard particle filter, additionally a large number of particles are required for accurate estimation. as it is difficult to meet the demand of modern infrared search and tracking system. To solve this problem, an improved infrared small target detection and tracking method based on closed-loop control bat algorithm optimized particle filter is proposed. Firstly, bat algorithm is introduced into the particle filtering in this method. Particles are used to simulate the process that an individual bat hunts and avoids obstacles so that particles move towards the high-likelihood region. Meanwhile, the improved algorithm takes the proportion of particles accepting a new state as the feedback quantity and proposes to conduct dynamic control on global and local search ability of particle filtering by closed-loop control strategy, which further improves the overall quality of particle distribution. The performance of the improved detection and tracking algorithm is tested in simulation scene and real scene of infrared small target. Experimental results show that the improved algorithm improves the performance of the infrared searching and tracking system.
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Abdullahi Daniyan. "Robust Multi-Target Tracking with a Kalman-Gain CPHD Filter: Simulation and Experimental Validation." World Journal of Advanced Engineering Technology and Sciences 15, no. 1 (2025): 1636–47. https://doi.org/10.30574/wjaets.2025.15.1.0369.
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We introduce a novel cardinalized implementation of the Kalman-gain-aided particle probability hypothesis density (KG-SMC-PHD) filter, extending it to form the Kalman-Gain Particle Cardinalized Probability Hypothesis Density (KG-SMC-CPHD) filter. This new approach significantly enhances multi-target tracking by combining the particle-based state correction mechanism with the propagation of both the PHD and target cardinality distribution. Unlike conventional particle filters that require a large number of particles for acceptable performance, our method intelligently corrects selected particles during the weight update stage, resulting in a more accurate posterior with substantially fewer particles. Through comprehensive evaluations on both simulated and experimental datasets, the KG-SMC-CPHD filter demonstrates superior robustness and accuracy, particularly in high-clutter environments and nonlinear target dynamics. Notably, it offers improved cardinality estimation and maintains the computational efficiency and performance advantages of its predecessor, the KG-SMC-PHD filter, making it a powerful tool for advanced multi-target tracking applications.
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Ashworth Briggs, Alexander, Alan Fleming, Jonathan Duffy, and Jonathan R. Binns. "Tracking the vortex core from a surface-piercing flat plate by particle image velocimetry and numerical simulation." Proceedings of the Institution of Mechanical Engineers, Part M: Journal of Engineering for the Maritime Environment 233, no. 3 (2018): 793–808. http://dx.doi.org/10.1177/1475090218776202.
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The wake flow around the tip of a surface piercing flat plate at an angle of incidence was studied using two-dimensional particle image velocimetry as part of benchmarking the particle image velocimetry technique on the moving carriage in the Australian Maritime College towing tank. Particle image velocimetry results were found to be in close agreement with those of the benchmarking work presented by the Hydro Testing Alliance, and a method of tracking the tip-vortex core near a free surface throughout numerical simulation has been demonstrated. Issues affecting signal to noise ratio, such as specula reflections from the free surface and model geometry were overcome through the use of fluorescing particles and a high-pass optical filter. Numerical simulations using the ANSYS CFX Solver with the volume of fluid method were validated against the experimental results, and a methodology was developed for tracking the location of the wandering vortex core experimentally and through simulation. The ability of the scale-adaptive simulation shear stress transport turbulence model and the shear stress transport model to simulate three-dimensional flow with high streamline curvature was compared. The scale-adaptive simulation shear stress transport turbulence model was found to provide a computationally less resource-intensive method of simulating a complex flow topology with large eddies, providing an insight into a possible cause of tip-vortex aperiodic wandering motion. At high angles of attack, vortex shedding from the leading edge separation of the test geometry is identified as a possible cause of the wandering phenomena. In this study, the vortex centre and point of extreme core velocity were found not to be co-located. The point of extreme stream wise velocity within the vortex core was found to be located within half the vortex radius of the vortex centre.
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Sieverding, Andre, Preston G. Waldrop, J. Austin Harris, et al. "Tracer Particles for Core-collapse Supernova Nucleosynthesis: The Advantages of Moving Backward." Astrophysical Journal 950, no. 1 (2023): 34. http://dx.doi.org/10.3847/1538-4357/acc8d1.
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Abstract After decades, the theoretical study of core-collapse supernova explosions is moving from parameterized, spherically symmetric models to increasingly realistic multidimensional simulations. However, obtaining nucleosynthesis yields based on such multidimensional core-collapse supernova simulations is not straightforward. Frequently, tracer particles are employed. Tracer particles may be tracked in situ during the simulation, but often they are reconstructed in a post-processing step based on the information saved during the hydrodynamic simulation. Reconstruction can be done in a number of ways, and here we compare the approaches of backward and forward integration of the equations of motion to the results based on inline particle trajectories. We find that both methods agree reasonably well with the inline results for isotopes for which a large number of particles contribute. However, for rarer isotopes that are produced only by a small number of particle trajectories, deviations can be large. For our setup, we find that backward integration leads to better agreement with the inline particles by more accurately reproducing the conditions following freeze-out from nuclear statistical equilibrium, because the establishment of nuclear statistical equilibrium erases the need for detailed trajectories at earlier times. Based on our results, if inline tracers are unavailable, we recommend backward reconstruction to the point when nuclear statistical equilibrium was last applied, with an interval between simulation snapshots of at most 1 ms for nucleosynthesis post-processing.
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Chao, Kuei-Hsiang, and Cheng-Chieh Hsieh. "Photovoltaic Module Array Global Maximum Power Tracking Combined with Artificial Bee Colony and Particle Swarm Optimization Algorithm." Electronics 8, no. 6 (2019): 603. http://dx.doi.org/10.3390/electronics8060603.
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In this study, the output characteristics of partial modules in a photovoltaic module array when subject to shading were first explored. Then, an improved particle swarm optimization (PSO) algorithm was applied to track the global maximum power point (MPP), with a multi-peak characteristic curve. The improved particle swarm optimization algorithm proposed, combined with the artificial bee colony (ABC) algorithm, was used to adjust the weighting, cognition learning factor, and social learning factor, and change the number of iterations to enhance the tracking performance of the MPP tracker. Finally, MATLAB software was used to carry out a simulation and prove the improved that the PSO algorithm successfully tracked the MPP in the photovoltaic array output curve with multiple peaks. Its tracking performance is far superior to the existing PSO algorithm.
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Parsons, Jasmine, Anatoly Spitkovsky, and Arno Vanthieghem. "Microphysics of Particle Reflection in Weibel-mediated Shocks." Astrophysical Journal 971, no. 1 (2024): 18. http://dx.doi.org/10.3847/1538-4357/ad527d.
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Abstract Particle-in-cell (PIC) simulations have shown that relativistic collisionless shocks mediated by the Weibel instability accelerate ∼1% of incoming particles, while the majority are transmitted through the shock and become thermalized. The microphysical processes that determine whether an incoming particle will be transmitted or reflected are poorly understood. We study the microphysics of particle reflection in Weibel-mediated shocks by tracking a shell of test particles in a PIC simulation of a shock in pair plasma. We find that electrons in positron-dominated filaments and positrons in electron-dominated filaments efficiently reflect off of strong magnetic structures at the shock. To participate in diffusive shock acceleration, however, these reflected particles headed toward the upstream must avoid getting advected downstream. This is enabled by incoming filaments, which trap reflected particles carrying the same sign of current as the filaments. The final injection efficiency on the order of ∼1% thus results from the effectiveness of the initial reflection at the shock and the reflected particles’ probability of survival in the upstream postreflection. We develop a model that predicts the fraction of high-energy particles as a function of the properties of Weibel filamentation.
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Puzyrev, Dmitry, Kirsten Harth, Torsten Trittel, and Ralf Stannarius. "Machine Learning for 3D Particle Tracking in Granular Gases." Microgravity Science and Technology 32, no. 5 (2020): 897–906. http://dx.doi.org/10.1007/s12217-020-09800-4.
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Abstract Dilute ensembles of granular matter (so-called granular gases) are nonlinear systems which exhibit fascinating dynamical behavior far from equilibrium, including non-Gaussian distributions of velocities and rotational velocities, clustering, and violation of energy equipartition. In order to understand their dynamic properties, microgravity experiments were performed in suborbital flights and drop tower experiments. Up to now, the experimental images were evaluated mostly manually. Here, we introduce an approach for automatic 3D tracking of positions and orientations of rod-like particles in a dilute ensemble, based on two-view video data analysis. A two-dimensional (2D) localization of particles is performed using a Mask R-CNN neural network trained on a custom data set. The problem of 3D matching of the particles is solved by minimization of the total reprojection error, and finally, particle trajectories are tracked so that ensemble statistics are extracted. Depending on the required accuracy, the software can work fully self-sustainingly or serve as a base for subsequent manual corrections. The approach can be extended to other 3D and 2D particle tracking problems.
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Liu, Qiaoran, and Xun Yang. "Improved Interacting Multiple Model Particle Filter Algorithm." Xibei Gongye Daxue Xuebao/Journal of Northwestern Polytechnical University 36, no. 1 (2018): 169–75. http://dx.doi.org/10.1051/jnwpu/20183610169.
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For the issue of limited filtering accuracy of interactive multiple model particle filter algorithm caused by the resampling particles don't contain the latest observation information, we made improvements on interactive multiple model particle filter algorithm in this paper based on mixed kalman particle filter algorithm. Interactive multiple model particle filter algorithm is proposed. In addition, the composed methods influence to tracking accuracy are discussed. In the new algorithm the system state estimation is generated with unscented kalman filter (UKF) first and then use the extended kalman filter (EKF) to get the proposal distribution of the particles, taking advantage of the measure information to update the particles' state. We compare and analyze the target tracking performance of the proposed algorithm of IMM-MKPF in this paper, IMM-UPF and IMM-EPF through the simulation experiment. The results show that the tracking accuracy of the proposed algorithm is superior to other two algorithms. Thus, the new method in this paper is effective. The method is of important to improve tracking accuracy further for maneuvering target tracking under the non-linear and non-Gaussian circumstances.
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Liu, Linshuang, Guolu Yang, and Minghui Yu. "Simulation for Sludge Flocculation I: Brownian Dynamic Simulation for Perikinetic Flocculation of Charged Particle." Mathematical Problems in Engineering 2012 (2012): 1–17. http://dx.doi.org/10.1155/2012/527384.
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To investigate sludge drying process, a numerical simulation based on Brownian dynamic for the floc with uncharged and charged particles was conducted. The Langevin equation is used as dynamical equation for tracking each particle in a floc. An initial condition and periodic boundary condition which well conformed to reality is used for calculating the floc growth process. Each cell consists of 1000 primary particles with diameter 0.1 ∼ 4 μm. Floc growth is related to the thermal force and the electrostatic force. The electrostatic force on a particle in the simulation cell is considered as the sum of electrostatic forces from other particles in the original cell and its replicate cells. It is assumed that flocs are charged with precharged primary particles in dispersion system by ionization. By the analysis of the simulation figures, on one hand, the effects of initial particle size and sludge density on floc smashing time, floc radius of gyration, and fractal dimension were discussed. On the other hand, the effects of ionization on floc smashing time and floc structure were presented. This study has important practical value in the high-turbidity water treatment, especially for sludge drying.
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Jones, Benjamin T., Andrew Solow, and Rubao Ji. "Resource Allocation for Lagrangian Tracking." Journal of Atmospheric and Oceanic Technology 33, no. 6 (2016): 1225–35. http://dx.doi.org/10.1175/jtech-d-15-0115.1.
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AbstractAccurate estimation of the transport probabilities among regions in the ocean provides valuable information for understanding plankton transport, the spread of pollutants, and the movement of water masses. Individual-based particle-tracking models simulate a large ensemble of Lagrangian particles and are a common method to estimate these transport probabilities. Simulating a large ensemble of Lagrangian particles is computationally expensive, and appropriately allocating resources can reduce the cost of this method. Two universal questions in the design of studies that use Lagrangian particle tracking are how many particles to release and how to distribute particle releases. A method is presented for tailoring the number and the release location of particles to most effectively achieve the objectives of a study. The method detailed here is a sequential analysis procedure that seeks to minimize the number of particles that are required to satisfy a predefined metric of result quality. The study assesses the result quality as the precision of the estimates for the elements of a transport matrix and also describes how the method may be extended for use with other metrics. Applying this methodology to both a theoretical system and a particle transport model of the Gulf of Maine results in more precise estimates of the transport probabilities with fewer particles than from uniformly or randomly distributing particle releases. The application of this method can help reduce the cost of and increase the robustness of results from studies that use Lagrangian particles.
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Kang, Jian, Wei Kang, and Guo Sheng Rui. "Study on Velocity Constrained Particle Filters in Passive Tracking Applications." Applied Mechanics and Materials 20-23 (January 2010): 482–86. http://dx.doi.org/10.4028/www.scientific.net/amm.20-23.482.
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To improve the poor performance of the maneuvering target tracking, Particle Filters (PF) and velocity constrained Particle Filters (VCPF) are introduced to track the maneuvering target. According to the prior information, outrange particles are discarded during prediction step, and the distribution and the weight of particles are adjusted. Simulation result shows that VCPF can track the maneuvering target stablely. Furthermore, the convergence rate and track accuracy of the algorithm can also be effectively improved.
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Reina, Francesco, John M. A. Wigg, Mariia Dmitrieva, Joël Lefebvre, Jens Rittscher, and Christian Eggeling. "TRAIT2D: a Software for Quantitative Analysis of Single Particle Diffusion Data." F1000Research 10 (August 20, 2021): 838. http://dx.doi.org/10.12688/f1000research.54788.1.
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Single particle tracking (SPT) is one of the most widely used tools in optical microscopy to evaluate particle mobility in a variety of situations, including cellular and model membrane dynamics. Recent technological developments, such as Interferometric Scattering microscopy, have allowed recording of long, uninterrupted single particle trajectories at kilohertz framerates. The resulting data, where particles are continuously detected and do not displace much between observations, thereby do not require complex linking algorithms. Moreover, while these measurements offer more details into the short-term diffusion behaviour of the tracked particles, they are also subject to the influence of localisation uncertainties, which are often underestimated by conventional analysis pipelines. we thus developed a Python library, under the name of TRAIT2D (Tracking Analysis Toolbox – 2D version), in order to track particle diffusion at high sampling rates, and analyse the resulting trajectories with an innovative approach. The data analysis pipeline introduced is more localisation-uncertainty aware, and also selects the most appropriate diffusion model for the data provided on a statistical basis. A trajectory simulation platform also allows the user to handily generate trajectories and even synthetic time-lapses to test alternative tracking algorithms and data analysis approaches. A high degree of customisation for the analysis pipeline, for example with the introduction of different diffusion modes, is possible from the source code. Finally, the presence of graphical user interfaces lowers the access barrier for users with little to no programming experience.
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Reina, Francesco, John M. A. Wigg, Mariia Dmitrieva, et al. "TRAIT2D: a Software for Quantitative Analysis of Single Particle Diffusion Data." F1000Research 10 (January 31, 2022): 838. http://dx.doi.org/10.12688/f1000research.54788.2.
Full textAbstract:
Single particle tracking (SPT) is one of the most widely used tools in optical microscopy to evaluate particle mobility in a variety of situations, including cellular and model membrane dynamics. Recent technological developments, such as Interferometric Scattering microscopy, have allowed recording of long, uninterrupted single particle trajectories at kilohertz framerates. The resulting data, where particles are continuously detected and do not displace much between observations, thereby do not require complex linking algorithms. Moreover, while these measurements offer more details into the short-term diffusion behaviour of the tracked particles, they are also subject to the influence of localisation uncertainties, which are often underestimated by conventional analysis pipelines. we thus developed a Python library, under the name of TRAIT2D (Tracking Analysis Toolbox – 2D version), in order to track particle diffusion at high sampling rates, and analyse the resulting trajectories with an innovative approach. The data analysis pipeline introduced is more localisation-uncertainty aware, and also selects the most appropriate diffusion model for the data provided on a statistical basis. A trajectory simulation platform also allows the user to handily generate trajectories and even synthetic time-lapses to test alternative tracking algorithms and data analysis approaches. A high degree of customisation for the analysis pipeline, for example with the introduction of different diffusion modes, is possible from the source code. Finally, the presence of graphical user interfaces lowers the access barrier for users with little to no programming experience.
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Li, Zhihao, Junkang Wu, Zhenwu Kuang, et al. "Moving Target Tracking Algorithm Based on Improved Resampling Particle Filter in UWB Environment." Wireless Communications and Mobile Computing 2022 (June 20, 2022): 1–16. http://dx.doi.org/10.1155/2022/9974049.
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In this paper, a moving target tracking (MTT) algorithm based on the improved resampling particle filter (IRPF) was put forward for the reduced accuracy of particle filter (PF) due to the lack of particle diversity resulting from traditional resampling methods. In this algorithm, the influences of the likelihood probability distribution of particles on the PF accuracy were firstly analyzed to stratify the adaptive regions of particles, and a particle diversity measurement index based on stratification was proposed. After that, a threshold was set for the particle diversity after resampling. If the particle diversity failed to reach the set threshold, all new particles would be subjected to a Gaussian random walk in a preset variance matrix to improve the particle diversity. Finally, the performance of related algorithms was tested in both simulation environment and actual indoor ultrawideband (UWB) nonline-of-sight (NLOS) environment. The experimental results revealed that the nonlinear target state estimation accuracy was maximally and minimally improved by 12.83% and 1.97%, respectively, in the simulation environment, and the root mean square error (RMSE) of MTT was reduced from 17.131 cm to 10.471 cm in actual UWB NLOS environment, indicating that the IRPF algorithm can enhance the target estimation accuracy and state tracking capability, manifesting better filter performance.
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Hoffmann, Alex C., Daniel Fonnes, and Yu-Fen Chang. "Flowpattern in hydrocyclones, numerical simulations with experimental verification." Journal of Physics: Conference Series 2675, no. 1 (2023): 012029. http://dx.doi.org/10.1088/1742-6596/2675/1/012029.
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Abstract This paper reports a detailed study of the flow in cyclone separators, with the use of most up to date computational fluid dynamics simulations, which are validated with positron emission particle tracking (PEPT) experiments tracing the movement of particles through the cyclone. The parameters varied were the viscosity of the carrier liquid, the flowrate and, in the numerical simulations, the inlet configurations of the cyclone, namely one and two inlets and, with the two inlets, a) both at right angles to the cyclone axis and b) angled downwards. The study reveals features of the flow, which have not been seen till now, but are necessary for the understanding and modelling of the separation and purification efficiency of cyclones. The results of the simulations and the close agreement with experiment are a testament to the reliability and accuracy of large eddy simulation (LES), even for flow features as difficult to simulate as the confined strongly swirling flows in cyclone separators. The results show that a contiguous, smooth surface of zero axial velocity does exist and has approximately the shape that has been assumed by modellers. The significant effects of fluid viscosity, underflow and modifications to the inlet are also shown.
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Jiang, Zitao, Tomohiro Kobayashi, Mats Sandberg, Toshio Yamanaka, Narae Choi, and Kayuki Sano. "Statistical Analysis Approach of Single-sided Ventilation Based on Particle Track Technique Using Large Eddy Simulation." E3S Web of Conferences 396 (2023): 02012. http://dx.doi.org/10.1051/e3sconf/202339602012.
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The main objective of this study is to investigate the airflow characteristics in single-sided ventilation. A CFD method of large eddy simulation (LES) using particle track technique was conducted in this study, and the simulation results are validated by experiment results. The mostly used ventilation efficiency indicators of natural ventilation are Air Flow Rate (AFR) and Purging Flow Rate (PFR). AFR is the volumetric airflow exchange rate through the openings and PFR is the effective airflow rate that removes indoor air pollutants. The ventilation efficiency (εν) of natural ventilation, which is defined as the ratio of PFR and AFR, is not well investigated in previous research, therefore, this study discusses the case of the εν of single-sided ventilation and tries to explain the distinction between AFR and PFR by statistical analysis approach based on particle movements. Particles are emitted from the opening and the particles’ movements are tracked by tracing their locations at different time steps. The residence time measures the time between the time that particles enter the room and the time that particles leave the room, and indoor travel distance indicates the sum of the displacement when the particle travels in the room. The Probability Density Function (PDF) of the residence time and indoor travel distance is used to depict airflow characteristics of the ventilation path of single-sided ventilation. The analysis method of study might be another useful approach to studying natural ventilation in detail.
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Tao, Yong, Fan Ren, He Gao, et al. "A Robot Dynamic Target Grasping Method Based on Affine Group Improved Gaussian Resampling Particle Filter." Applied Sciences 11, no. 21 (2021): 10270. http://dx.doi.org/10.3390/app112110270.
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Tracking and grasping a moving target is currently a challenging topic in the field of robotics. The current visual servo grasping method is still inadequate, as the real-time performance and robustness of target tracking both need to be improved. A target tracking method is proposed based on improved geometric particle filtering (IGPF). Following the geometric particle filtering (GPF) tracking framework, affine groups are proposed as state particles. Resampling is improved by incorporating an improved conventional Gaussian resampling algorithm. It addresses the problem of particle diversity loss and improves tracking performance. Additionally, the OTB2015 dataset and typical evaluation indicators in target tracking are adopted. Comparative experiments are performed using PF, GPF and the proposed IGPF algorithm. A dynamic target tracking and grasping method for the robot is proposed. It combines an improved Gaussian resampling particle filter algorithm based on affine groups and the positional visual servo control of the robot. Finally, the robot conducts simulation and experiments on capturing dynamic targets in the simulation environment and actual environment. It verifies the effectiveness of the method proposed in this paper.
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Brunel, Marc, Lila Ouldarbi, Alexandre Fahy, and Gaële Perret. "3D-Tracking of Sand Particles in a Wave Flume Using Interferometric Imaging." Optics 3, no. 3 (2022): 254–67. http://dx.doi.org/10.3390/opt3030025.
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We report the 3D-tracking of irregular sand particles in a wave flume using a cylindrical interferometric particle imaging set-up. The longitudinal position of each particle is deduced from the ellipticity of its speckle-like interferometric image. The size of a particle is determined from the analysis of the 2D Fourier transform of its defocused image. It is further possible to identify some rotation of the particles. Simulations accurately confirm the experimental determination of the different parameters (3D position and size of each particle).
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Wang, Lian-Ping, and D. E. Stock. "Numerical Simulation of Heavy Particle Dispersion Time Step and Nonlinear Drag Considerations." Journal of Fluids Engineering 114, no. 1 (1992): 100–106. http://dx.doi.org/10.1115/1.2909983.
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Numerical experiments can be used to study heavy particle dispersion by tracking particles through a numerically generated instantaneous turbulent flow field. In this manner, data can be generated to supplement physical experiments. To perform the numerical experiments efficiently and accurately, the time step used when tracking the particles through the fluid must be chosen correctly. After finding a suitable time step for one particular simulation, the time step must be reduced as the total integration time increases and as the free-fall velocity of the particle increases. Based on the numerical calculations, we suggest that the nonlinear drag be included in a numerical simulation if the ratio of the particle’s Stokes free-fall velocity to the fluid rms velocity is greater than two.
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Kong, Hongshan, and Bin Yu. "A Moving Object Indoor Tracking Model Based on Semiactive RFID." Mathematical Problems in Engineering 2018 (December 25, 2018): 1–7. http://dx.doi.org/10.1155/2018/4812057.
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Aimed at the weak anti-interference and low accuracy problem of moving object indoor tracking based RFID, a moving object indoor tracking model based on semiactive RFID is presented. This model acquires scene location information through RFID low frequency triggers preinstalled, which can enhance the anti-interference ability. This model adopts an improved particle filter algorithm, which can increase the diversity of the particles, overcome the particle impoverishment, and reduce the tracking error. Simulation results indicate that the model can achieve better tracking performances. Compared with standard particle filter, the improved algorithm performance is better in the capability of tracking accuracy and robust and is more suitable for indoor tracking application in the complicated environments.
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Dodds, David, Abd Alhamid R. Sarhan, and Jamal Naser. "CFD Investigation into the Effects of Surrounding Particle Location on the Drag Coefficient." Fluids 7, no. 10 (2022): 331. http://dx.doi.org/10.3390/fluids7100331.
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In the simulation of dilute gas-solid flows such as those seen in many industrial applications, the Lagrangian Particle Tracking method is used to track packets of individual particles through a converged fluid field. In the tracking of these particles, the most dominant forces acting upon the particles are those of gravity and drag. In order to accurately predict particle motion, the determination of the aforementioned forces become of the upmost importance, and hence an improved drag force formula was developed to incorporate the effects of particle concentration and particle Reynolds number. The present CFD study examines the individual effects of particles located both perpendicular and parallel to the flow direction, as well as the effect of a particle entrain within an infinite matrix of evenly distributed particles. Results show that neighbouring particles perpendicular to the flow (Model 2) have an effect of increasing the drag force at close separation distances, but this becomes negligible between 5–10 particle diameters depending on particle Reynolds number (Rep). When entrained in an infinite line of particles co-aligned with the flow (Model 1), the drag force is remarkably reduced at close separation distances and increases as the distance increases. The results of the infinite matrix of particles (Model 3) show that, although not apparent in the individual model, the effect of side particles is experienced many particle diameters downstream.
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Xu, Dan, Zhanhong Wan, Luping Li, Xiuyang Lu, Jiawang Chen, and Bingru Li. "Simulation of spray droplets over the ocean surface." Thermal Science 23, no. 4 (2019): 2171–77. http://dx.doi.org/10.2298/tsci1904171x.
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Spray droplets, ejected from the ocean surface, are known to transport in the marine atmospheric boundary-layer, in which they exchange momentum and heat with the atmosphere. This paper gives a numerical approach to description of sea spray drops. Large eddy simulation is used to perform the air-flow over the sea surface while simultaneously tracking the trajectories of Lagrangian point-particle elements designed to represent spray particles in air, the particle mo-mentum relaxation time, the suspension time, the velocity of particles in different radii and different wind speeds are discussed. This simplified model shows that the contribution of droplet particles to the air-sea momentum transport cannot be ignored. The spray droplets suspended over the sea surface are once formed, they will accelerate to the local wind speed in less than 1 second, and thereby the drops can extract momentum from the wind, reduce sea surface wind speed and eventually plunge back into the ocean. The averaged particle concentration is balanced by an equivalent production of new particles.
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Wang, Anquan, and Michael F. Modest. "Photon Monte Carlo Simulation for Radiative Transfer in Gaseous Media Represented by Discrete Particle Fields." Journal of Heat Transfer 128, no. 10 (2006): 1041–49. http://dx.doi.org/10.1115/1.2345431.
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Monte Carlo ray-tracing schemes have been developed for the evaluation of radiative heat transfer for problems, in which the participating medium is represented by discrete point masses, such as the flow field and scalar fields in PDF Monte Carlo methods frequently used in combustion modeling. Photon ray tracing in such cases requires that an optical thickness is assigned to each of the point masses. Two approaches are discussed, the point particle model (PPM), in which the shape of particle is not specified, and the spherical particle model (SPM) in which particles are assumed to be spheres with specified radiation properties across their volumes. Another issue for ray tracing in particle fields is the influence region of a ray. Two ways of modeling a ray are proposed. In the first, each ray is treated as a standard volume-less line. In the other approach, the ray is assigned a small solid angle, and is thus treated as a cone with a decaying influence function away from its centerline. Based on these models, three different interaction schemes between rays and particles are proposed, i.e., line-SPM, cone-PPM and cone-SPM methods, and are compared employing several test problems.
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Ikoma, Norikazu, Ryuichi Yamaguchi, Hideaki Kawano, and Hiroshi Maeda. "Tracking of Multiple Moving Objects in Dynamic Image of Omni-Directional Camera Using PHD Filter." Journal of Advanced Computational Intelligence and Intelligent Informatics 12, no. 1 (2008): 16–25. http://dx.doi.org/10.20965/jaciii.2008.p0016.
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A method of multiple moving objects tracking in dynamic image of omni-directional camera has been proposed. Finite random set (FRS) based state space model is employed in the method due to its inherent nature capable to represent the scene having occlusion and appearance of object as well as missing and false detection in observation. Sequential Monte Carlo (SMC) implementation of Probability hypothesis density (PHD) filter has been used for estimating state of the state space model. The state is a finite random set of single object states, where each element of the set consists of position and velocity of the object in panoramic image coordinate of omni-directional camera image. We propose a new method to display tracking result from weighted particles obtained from the estimation process by SMC implementation of PHD filter. Key idea of the method is to put an integer label on each particle, where the label indicates specific object among multiple objects in the image scene tracked by the particle. Numerical simulation and real image experiments illustrate tracking performance of the proposed method.
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Wu, Jiaxiong, Yanhua Shen, Shudi Yang, and Zhipeng Feng. "Simulation of Track-Soft Soil Interactions Using a Discrete Element Method." Applied Sciences 12, no. 5 (2022): 2524. http://dx.doi.org/10.3390/app12052524.
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With the development of unmanned tracked vehicles, soil model predictions of soft terrains are becoming more essential. In order to accurately simulate the interaction characteristics between soil particles and the track, soil modeling with a discrete element method (DEM) is proposed. Volume-based scaled-up modeling of DEM soil particles and the calibration of DEM input parameters were investigated as a feasible approach to realizing many particle calculations. Calibration of DEM input parameters can solve the distortions between actual and DEM particle sizes. Cohesion and friction parameters of the scaled-up soil particle model were recalibrated by the shape accumulated through the virtual design of the experiment. Soil DEM particles were scaled up to 1 mm spherical particles, and recalibrated DEM parameter values were used to match the actual accumulated soil shape. Three calibrated scaled-up soil models were used for the shear stress–displacement DEM simulation of a track segment, and the mean absolute percentage error (MAPE) was less than 11% compared with the actual shear stress–displacement test. The parameter value of soil traction performance empirical model of a tracked vehicle is modified according to the soil shear stress–displacement DEM simulation. Comparative analysis was performed for travel test results of a tracked vehicle; the relative error of the soil traction prediction results to actuals was less than 16.8%. This showed that the volume-based particle scaling technique is an effective DEM for the mechanical simulation of soil.
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Qiao, Yu Kun, Qi Zhang, and Jin Sheng Zhang. "A Fault Predication Algorithm Based on Artificial Immune Particle Filter." Applied Mechanics and Materials 44-47 (December 2010): 3459–63. http://dx.doi.org/10.4028/www.scientific.net/amm.44-47.3459.
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Degeneracy problem is an inevitable result of sequential importance re-sampling (SIR) particle filter, and a mass of degenerated particles will influence the tracking ability of particle filter seriously. As a result, SIR particle filter based predication algorithm can’t predict system faults accurately. Artificial immune algorithm is characterized by a global ability to search for optimum, so it is introduced into the particle filter, named artificial immune particle filter (AIPF). Particles are regarded as antibodies in AIPF and particles with large weight aberrance and are cloned, and then the better particles are selected for states evaluation. A fault predication algorithm based on AIPF is proposed to improve the predication accuracy, and simulation results have demonstrated the feasibility of the proposed algorithm.
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Huilier, Daniel G. F. "An Overview of the Lagrangian Dispersion Modeling of Heavy Particles in Homogeneous Isotropic Turbulence and Considerations on Related LES Simulations." Fluids 6, no. 4 (2021): 145. http://dx.doi.org/10.3390/fluids6040145.
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Particle tracking is a competitive technique widely used in two-phase flows and best suited to simulate the dispersion of heavy particles in the atmosphere. Most Lagrangian models in the statistical approach to turbulence are based either on the eddy interaction model (EIM) and the Monte-Carlo method or on random walk models (RWMs) making use of Markov chains and a Langevin equation. In the present work, both discontinuous and continuous random walk techniques are used to model the dispersion of heavy spherical particles in homogeneous isotropic stationary turbulence (HIST). Their efficiency to predict particle long time dispersion, mean-square velocity and Lagrangian integral time scales are discussed. Computation results with zero and no-zero mean drift velocity are reported; they are intended to quantify the inertia, gravity, crossing-trajectory and continuity effects controlling the dispersion. The calculations concern dense monodisperse spheres in air, the particle Stokes number ranging from 0.007 to 4. Due to the weaknesses of such models, a more sophisticated matrix method will also be explored, able to simulate the true fluid turbulence experienced by the particle for long time dispersion studies. Computer evolution and performance since allowed to develop, instead of Reynold-Averaged Navier-Stokes (RANS)-based studies, large eddy simulation (LES) and direct numerical simulation (DNS) of turbulence coupled to Generalized Langevin Models. A short review on the progress of the Lagrangian simulations based on large eddy simulation (LES) will therefore be provided too, highlighting preferential concentration. The theoretical framework for the fluid time correlation functions along the heavy particle path is that suggested by Wang and Stock.
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Li, Debo, Qisheng Xu, Yaming Liu, Yin Libao, and Jin Jun. "Numerical Simulation of Particles Deposition in a Human Upper Airway." Advances in Mechanical Engineering 6 (January 1, 2014): 207938. http://dx.doi.org/10.1155/2014/207938.
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Based on the CT scanned images, a realistic geometric model from nasal cavity to upper six-generation bronchia is rebuilt. In order to effectively simulate the particle movement and deposition, LES model is used and the particles are tracked in the frame of Lagrange. Seven kinds of typical particles, including micron particles (1, 5, and 10 μm) and nanoparticles (1, 5, 20, and 100 nm), and three representative respiratory intensities are adopted as computational case, respectively. Deposition efficiency ( D E), deposition concentration ( D C), and capture efficiency ( C E) are introduced. Furthermore, the locations of particle deposition are visualized. The results indicate that the injecting particles from different nasal inlet present “transposition effect.”The D E values of micron particles are much higher than nanoparticles. The particle diameter plays a weaker role in nanoparticle depositions than micron particles. The highest values of D E and D C both occur in nasal cavity, while the highest C E up to 99.5% occurs in bronchus region.
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Wang, Junwen, Jichao Lin, Jianchun Wang, Yongwei Mao, Songying Chen, and Guichao Wang. "Comparative Study of Particle-Resolved and Point-Particle Simulations of Particle–Bubble Collisions in Homogeneous Isotropic Turbulence." Minerals 15, no. 4 (2025): 338. https://doi.org/10.3390/min15040338.
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Bubble–particle collisions in turbulent flows are fundamental to flotation processes, yet their complex dynamics remain challenging to characterize accurately. In this study, a comparison study of a particle–bubble collision system in homogeneous isotropic turbulence was performed using the particle-resolved method and point-particle method. Direct numerical simulations of turbulent flows were achieved using the lattice Boltzmann method (LBM). The effects of hydrodynamics on the collision particles were compared between Lagrangian tracking and directly resolving the disturbance flows around finite-size solid particles using an interpolated bounce-back scheme. The differences between point-particle and particle-resolved simulations are evaluated, highlighting their respective strengths and limitations. These findings enhance the understanding of turbulence-driven bubble–particle interactions and provide guidance for improving the accuracy of flotation modeling and process optimization.
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Starodumov, Ilya, Sergey Sokolov, Ksenia Makhaeva, Pavel Mikushin, Olga Dinislamova, and Felix Blyakhman. "Obtaining Vortex Formation in Blood Flow by Particle Tracking: Echo-PV Methods and Computer Simulation." Inventions 8, no. 5 (2023): 124. http://dx.doi.org/10.3390/inventions8050124.
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Micrometer-sized particles are widely introduced as fluid flow markers in experimental studies of convective flows. The tracks of such particles demonstrate a high contrast in the optical range and well illustrate the direction of fluid flow at local vortices. This study addresses the theoretical justification on the use of large particles for obtaining vortex phenomena and its characterization in stenotic arteries by the Echo Particle Velocimetry method. Calcite particles with an average diameter of 0.15 mm were chosen as a marker of streamlines using a medical ultrasound device. The Euler–Euler model of particle motion was applied to simulate the mechanical behavior of calcite particles and 20 µm aluminum particles. The accuracy of flow measurement at vortex regions was evaluated by computational fluid dynamics methods. The simulation results of vortex zone formation obtained by Azuma and Fukushima (1976) for aluminum particles with the use of the optical velocimetry method and calcite particles were compared. An error in determining the size of the vortex zone behind of stenosis does not exceed 5%. We concluded that the application of large-size particles for the needs of in vitro studies of local hemodynamics is possible.
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Ding, Wen Jun, Jeremy Zhen Jie Lim, Hue Thi Bich Do, et al. "Particle simulation of plasmons." Nanophotonics 9, no. 10 (2020): 3303–13. http://dx.doi.org/10.1515/nanoph-2020-0067.
Full textAbstract:
AbstractParticle simulation has been widely used in studying plasmas. The technique follows the motion of a large assembly of charged particles in their self-consistent electric and magnetic fields. Plasmons, collective oscillations of the free electrons in conducting media such as metals, are connected to plasmas by very similar physics, in particular, the notion of collective charge oscillations. In many cases of interest, plasmons are theoretically characterized by solving the classical Maxwell’s equations, where the electromagnetic responses can be described by bulk permittivity. That approach pays more attention to fields rather than motion of electrons. In this work, however, we apply the particle simulation method to model the kinetics of plasmons, by updating both particle position and momentum (Newton–Lorentz equation) and electromagnetic fields (Ampere and Faraday laws) that are connected by current. Particle simulation of plasmons can offer insights and information that supplement those gained by traditional experimental and theoretical approaches. Specifically, we present two case studies to show its capabilities of modeling single-electron excitation of plasmons, tracing instantaneous movements of electrons to elucidate the physical dynamics of plasmons, and revealing electron spill-out effects of ultrasmall nanoparticles approaching the quantum limit. These preliminary demonstrations open the door to realistic particle simulations of plasmons.
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Batchelder, Harold P. "Forward-in-Time-/Backward-in-Time-Trajectory (FITT/BITT) Modeling of Particles and Organisms in the Coastal Ocean*." Journal of Atmospheric and Oceanic Technology 23, no. 5 (2006): 727–41. http://dx.doi.org/10.1175/jtech1874.1.
Full textAbstract:
Abstract Lagrangian particle-tracking models (LPTMs) were used to identify sources, destinations, and transport pathways of particles (plankton). The LPTM simulations were forced using stored fields from the Spectral Element Ocean Model simulation for a coastal upwelling system having idealized geometry, bathymetry, and simple wind forcing. Forward-in-time-trajectory (FITT) simulations are common in ocean science, although they often do not include diffusion. Results from LPTM comparisons with and without diffusion suggest that ignoring diffusion can lead to incorrect identification of source or destination regions. FITT is efficient for identifying destinations from known sources, but inefficient for identifying sources from known destinations (or receptors). Backward-in-time-trajectory (BITT) modeling from known destinations efficiently identifies sources, or particle positions, at earlier times. Although advection and some biological processes (e.g., growth) are reversible and amenable to BITT simulations, other processes, such as physical diffusion, reproduction, and mortality, are not time reversible. The reliability of BITT-derived estimates of prior particle positions was evaluated using a BITT followed by a FITT coupled approach. The results suggest that BITT approaches are valuable in identifying probability densities of prior positions. Such information is particularly useful in the ocean sciences where many of the interesting questions concern where particles (e.g., plankton, meroplankton) have been (or came from) rather than where they are headed (identifying the destination). BITT simulations provide a computationally efficient technique to examine these questions.