Maximum Number Of Particles Research Articles

Chemical herding as a multiplicative factor for top-down manipulation of colloids.

Colloidal particles can create reconfigurable nanomaterials, with applications such as color-changing, self-repairing, and self-regulating materials and reconfigurable drug delivery systems. However, top-down methods for manipulating colloids are limited in the scale they can control. We consider here a new method for using chemical reactions to multiply the effects of existing top-down colloidal manipulation methods to arrange large numbers of colloids with single-particle precision, which we refer to as chemical herding. Using simulation-based methods, we show that if a set of chemically active colloids (herders) can be steered using external forces (i.e., electrophoretic, dielectrophoretic, magnetic, or optical forces), then a larger set of colloids (followers) that move in response to the chemical gradients produced by the herders can be steered using the control algorithms given in this paper. We also derive bounds that predict the maximum number of particles that can be steered in this way, and we illustrate the effectiveness of this approach using Brownian dynamics simulations. Based on the theoretical results and simulations, we conclude that chemical herding is a viable method for multiplying the effects of existing colloidal manipulation methods to create useful structures and materials.

Particle Formation Mechanism of TiCl4 Hydrolysis to Prepare Nano TiO2

This study utilizes Aspen Plus chemical process simulation software (V11), applies uniform nucleation theory and growth kinetics equations, and explores the particle formation mechanism of TiCl4 hydrolysis to prepare nano TiO2. In the water/ethanol system, the effects of the reaction time, reaction temperature, water addition, pH value, and ethanol amount on the crystal nucleation rate and TiO2 particle distribution (PSD) were studied in detail by adding triethanolamine dropwise and using the Aspen Plus chemical process software simulation calculation method. The calculation results indicate that at room temperature, the formation of TiO2 crystal nuclei mainly occurs in the first 300 s and then enters the growth stage. The reaction was carried out under neutral conditions at room temperature for 4 h in 1 mL TiCl4, 6 mL C6H15NO3, 15 mL H2O, and 30 mL C2H5OH. The maximum number of particles reached 195 mesh per cubic micrometer, and the particle size after crystal nucleus growth was smaller, with a D50 of 6.15 nm. The distribution curve shows a normal distribution, which is basically consistent with the experimental results. When studying various factors, it was found that controlling the reaction time within 60 min and maintaining the reaction temperature at room temperature can reduce the particle size D50 to 2.44 nm. Continuing to adjust the amount of water added, it was found that at 1 mL, D50 decreased again to 0.19 nm. Adjusting the pH value found that maintaining the neutrality did not change the particle size. Continuing to adjust ethanol, it was found that adding an appropriate amount of ethanol promoted nucleation and growth. At 4 mL, the maximum number of particles reached 199 mesh per cubic micrometer, but D50 slightly increased to 0.24 nm.

Combined Funnel, Concentrator, and Particle Valve Functional Element for Magnetophoretic Bead Transport Based on Engineered Magnetic Domain Patterns.

Controlled actuation of superparamagnetic beads (SPBs) within a microfluidic environment using tailored dynamic magnetic field landscapes (MFLs) is a potent approach for the realization of point-of-care diagnostics within Lab-on-a-chip (LOC) systems. Making use of an engineered magnetic domain pattern as the MFL source, a functional LOC-element with combined magnetophoretic "funnel", concentrator, and "valve" functions for micron-sized SPBs is presented. A parallel-stripe domain pattern design with periodically decreasing/increasing stripe lengths is fabricated in a topographically flat continuous exchange biased (EB) thin film system by ion bombardment induced magnetic patterning (IBMP). It is demonstrated that, upon application of external magnetic field pulses, a fully reversible concentration of SPBs at the domain pattern's focal point occurs. In addition, it is shown that this functionality may be used as an SPB "funnel", allowing only a maximum number of particles to pass through the focal point. Adjusting the pulse time length, the focal point can be clogged up for incoming SPBs, resembling an on/off switchable particle "valve". The observations are supported by quantitative theoretical force considerations.

Targeted drug delivery during radioembolization in a comprehensive hepatic artery system: A computational study

Nonresectable liver tumors can be successfully treated with radioembolization (RE) using yttrium-90 (90Y) microspheres. However, hepatocellular carcinoma's therapeutic methods are hindered primarily by the complex arterial morphology of the liver and its high dependence on arteries' geometry to target the tumors. Thus, this study aims to investigate the particle-fluid dynamics of yttrium-90 (90Y) loaded microspheres injected into the blood flow within a comprehensive hepatic artery system consisting of 17 daughter vessels branches. Also, the effect of particles' characteristics (size and density) with two types of commercially available 90Y microspheres, SIR-Spheres and TheraSpheres, and time infusion intervals (various release phases) were studied leading to a total of 20 investigated cases. The results demonstrated the vital influence of flow dynamics on the particles' preference to deposit in specific daughter vessels. Regardless of phase shift, except GDA, outlet 1 receives the largest portion of CHA inflow with nearly 14.5% which consequently implies the highest value of exit fraction after particles injection, and outlet 11 receives the minimum portion of CHA inflow with 1.97%. The maximum and minimum reductions of mean flow rate through the phase shift from acceleration toward minimum phase are for daughter vessels 17 and 10 with nearly 17.7% and 4.8%, respectively. The maximum percentage of particles that remains in the domain after 4 heart cycle simulation time is for glass microspheres consisting of particles with the diameter of 80μm released at t=0 sec, indicating that 25.4% of the injected particles are unable to discharge the domain. Whereas, the minimum percentage (0.16%) of remaining particles is for resin microspheres with a diameter of 20μm released at t=0 sec. Moreover, regardless of particles type, 7 daughter vessels discharge their maximum number of particles at the time point of injection associated with the minimum velocity of CHA flow rate which highlights the significant importance of minimum phase for those daughter vessels, potentially terminating tumor cells. Results exhibit that for none of the daughter vessels, the acceleration phase and peak phase (except for the GDA outlet) are proper time zones to release the 90Y microspheres, regardless of particles type. Finally, to conduct the released particles to particular vessels which are connected to tumor cells, the best radial position of the micro-catheter at the CHA inlet cross-section was identified by generating particle release maps (PRMs) for each investigated case.

A 3D Monte Carlo Simulation for Aerosol Deposition onto Horizontal Surfaces by Combined Mechanisms of Brownian Diffusion and Gravity Sedimentation

A three-dimensional Monte Carlo model was developed to simulate the deposition of aerosol particles onto horizontal solid surfaces. The random walk method was employed to solve the particle transport equation, which allowed obtaining the trajectory of particle motion by a combined mechanism of Brownian diffusion and gravity sedimentation. The particle transport mechanism was described in terms of a Peclet number (Pe). The local structures of the dust layer, the relationship between the structure of the dust layer and particle transport mechanisms, and the number of the particles attached to the solid surface were investigated. The results showed that for a small Pe, when Brownian diffusion was a controlling mechanism for aerosol transport, the dust layer might exhibit a more open and looser structure, while for a large Pe, the dust layer was dense and tight. The differences of deposition morphologies under different transport mechanisms were caused by the different random intensities of particle motion. There was an upper limit of the maximum number of particles attached to the surface, and it strongly depended on particle transport mechanisms and size distributions. Additionally, the deposit morphologies obtained with the 3D Monte Carlo model were in good agreement with the experimental results found in the literature.

Diffusion on a lattice: Transition rates, interactions, and memory effects.

We analyze diffusion of particles on a two-dimensional square lattice. Each lattice site contains an arbitrary number of particles. Interactions affect particles only in the same site, and are macroscopically represented by the excess chemical potential. In a recent work, a general expression for transition rates between neighboring cells as functions of the excess chemical potential was derived. With transition rates, the mean-field tracer diffusivity, D^{MF}, is immediately obtained. The tracer diffusivity, D=D^{MF}f, contains the correlation factor f, representing memory effects. An analysis of the joint probability of having given numbers of particles at different sites when a force is applied to a tagged particle allows an approximate expression for f to be derived. The expression is applied to soft core interaction (different values for the maximum number of particles in a site are considered) and extended hard core.

Investigation of the Relationship between Vibration Signals Due to Oil Impurity and Cavitation Bubbles in Hydraulic Pumps

Although hydraulic pumps are frequently used in daily life, improper use due to oil analysis or oil contamination is ignored. There is no instantaneous inspection; instead, the oil is changed periodically at certain times, whether it is contaminated or not. Hydraulic systems operate based on Pascal’s law, which states that the fluid will distribute the pressure equally to every point in a closed area. The fluid oil taken from an oil reservoir is moved into the pump by engine power. During this movement, as it passes through different pressure areas and different sections, undesirable events such as viscosity change and gas formation occur in the hydraulic oil. These formations collide with the outer walls and cause cavitation with respect to unwanted oil impurities. This cavitation causes unwanted vibration signals to occur in the normal working order of the system. As a result of cavitation, the particles that affect the lubricity and fluidity of the oil in the oil are mixed into the liquid and circulate freely. At the connection points, the blockage caused by the liquid in the pump cylinder block or the valve plate and the collisions of particles is effective. As a result, it creates vibrations of different frequencies. The frequency and amplitudes of these vibrations differ according to the degree of oil contamination. A method has been developed to find the degree of contamination of the oil circulating in the pump by looking at the amplitude and frequency of these vibrations measured from the motor body. There exist standards about the pollution of hydraulic fluid. With these standards, the maximum number of particles allowed for a given pollution level is defined. This topic is discussed in the conclusion to this study. This method has also been proven experimentally. Error and vibration analysis studies on pumps using a different approach are available in the literature. In these studies, pressure variation, total energy transmission, or artificial intelligence models were used to detect anomalies in the pump. In this study, the impurity rate of the oil was set at five different levels and the operating regime of the pump at each level was investigated experimentally. Rayleigh–Plesset and Zwart–Gerber–Belamri models, which are the most common cavitation models, were used to explain the bubble formation in the moving oil and the relationship of these bubbles with vibration. Frequency components were examined by the Discrete Fast Fourier Analysis method, where the operation of the pump was affected by the increase in oil impurity.

Analysis of Vector Particle-In-Cell (VPIC) memory usage optimizations on cutting-edge computer architectures

Vector Particle-In-Cell (VPIC) is one of the fastest plasma simulation codes in the world, with particle numbers ranging from one trillion on the first petascale system, Roadrunner, to ten trillion particles on the more recent Blue Waters supercomputer. As supercomputers continue to grow rapidly in size, so too does the gap between computing capability and memory capability. Current memory systems limit VPIC simulations greatly as the maximum number of particles that can be simulated directly depends on the available memory. In this study, we present a suite of VPIC memory optimizations (i.e., particle weight, half-precision, and fixed-point optimizations) that enable a significant increase in the number of particles in VPIC simulations. We assess the optimizations’ impact on memory and runtime performance for a suite of cutting-edge computer architectures such has the NVIDIA V100 GPU, the IBM Power9, and the Fujitsu A64FX architectures. Our optimizations enable a 31.25% reduction in memory usage and up to 40% increase in the number of particles. This paper extends our work on developing particle storage format optimizations Tan et al. (2021) [1].

Lonely Planets and Lightweight Asteroids: A Statistical Mechanics Model for the Planetary Problem

In this paper we propose a notion of stability, which we call varepsilon -N-stability, for systems of particles interacting via Newton’s gravitational potential, and orbiting a much bigger object. For these systems the usual thermodynamical stability condition, ensuring the possibility to perform the thermodynamical limit, fails, but one can use as relevant parameter the maximum number of particles N that guarantees the varepsilon -N-stability. With some judicious but not particularly optimized estimates, borrowed from the classical theory of equilibrium statistical mechanics, we show that our model has a good fit with the data observed in the Solar System, and it gives a reasonable interpretation of some of its global properties.

Confinement of an ultra-cold-matter wave packet near the delocalization threshold by a waveguide bend with two or more contact impurities

The properties of confined quantum systems are of fundamental importance in the understanding of quantum behavior at extreme conditions. One of such quantum systems at extreme conditions is an ultra-cold quantum matter wave packet confined by a square well potential. The square well potential could be produced by a bend in a waveguide in an atom chip. Of further interest is the presence of contact impurities inside the bend produced by guide defects. In order to study such a system, its properties are well described by the nonlinear Schrodinger equation. In this work, we generalize our previous work (Mendez-Fragoso and Cabrera-Trujillo in Eur J Phys D 69:139, 2015) to study the ground state behavior of a quantum matter wave packet under confinement by a bend modeled by an attractive square well potential of strength $$V_0$$ and width 2R in the presence of several contact impurities represented by delta potentials with strength $$\beta $$ placed inside it at the threshold of delocalization, i.e., at the point where the well has trapped the maximum number of particles. We find that the maximum number of atoms held by the squared well potential only depends on the total strength of the contact impurities and not on their position. This implies that the maximum number of trapped particles is the same for one or more contact impurities as long as the combined strength is the same. For small $$R \sqrt{V_0}$$ values of the squared well potential, the number of particles trapped at the delocalization threshold is lower than when no contact impurities are present and decreases more as the contact impurity repulsive strength increases. This induces a threshold on the maximum number of particles trapped by an attractive squared well at $$2R V_0=\sum _i\beta _i$$ . The matter wave packet profile shows the effect of the contact impurity as a wedge shape at the contact impurity position.

Coupled DEM-FDM simulation of cone penetration tests in coarse grained soils

The numerical modelling of geotechnical problems often poses major challenges when large displacements and strain localization are involved. Conventional continuum mechanical approaches like the finite element method (FEM) or the finite difference method (FDM) suffer from mesh distortion and numerical inaccuracy when large deformations are involved. In addition, they require the use of appropriate constitutive models to simulate the soil behaviour. The distinct element method is a promising alternative for large deformation analyses. It does not have the limitations resulting from the numerical discretization of the continuumand not need a constitutive model since the macroscopic response results from the individual particle interaction. However, the maximum number of particles and therefore the domain of the simulation is nowadays limited by the available computational capacity. To overcome this limitation, a coupled DEM-FDM approach is proposed used to optimize the number of particles for a combined numerical domain consisting of areas of large and small displacements. The performance of the coupled DEM-FDM approach is investigated by simulating cone penetration tests in coarse grained soils.

Multiple Object Tracking for Occluded Particles

The precise detection and tracking of multiple particles under a microscope are of significance in the research of the individual and cluster behavior of dynamic bacteria and subcellular structures. However, the existing detection algorithms cannot separate occluded particles from each other, and most of the tracking algorithms aimed to address the occlusion involve several uncertainties. In this paper, a two-step detection algorithm based on the threshold segmentation and morphological open operation has been developed for identify non-fluorescent labeled particles under microscope, which could separate micro-contact targets. Moreover, we have proposed a novel correlation algorithm that can exploit the strengths of the global shortest path algorithm and Hungarian algorithm, which updating online in real time and considering the occlusion among particles. The proposed approach could achieve the temporal optimal match and spatial optimal solution by utilizing the multi-frame information. Moreover, the proposed method could realize the tracking of occluded particles tracking, and outperform the single global shortest path algorithm and Hungarian algorithm. The proposed method was successfully applied to six real image sequences with the maximum number of particles per frame ranging from 23 to 55, as well as a synthetic and fluorescent labeled sequence. The results of the contrast experiments demonstrated that the proposed algorithm is practical and can realize real-time tracking.

Notes on statistical ensembles in the Cell Model

Properties of basic statistical ensembles in the Cell Model are discussed. The simplest version of the model with a fixed total number of particles is considered. The microcanonical ensembles of distinguishable and indistinguishable particles, with and without a limit on the maximum number of particles in a single cell, are discussed. The joint probability distributions of particle multiplicities in cells for different ensembles are derived, and their second moments are calculated. The results for infinite volume limit are calculated. The obtained results resemble those in the statistical physics of bosons, fermions and boltzmanions.

Catalytic hydrolysis of sodium borohydride solution for hydrogen production using thermal plasma synthesized nickel nanoparticles

In the present study nickel nanoparticles were synthesized by thermal plasma route. In this method we obtained highly crystalline almost spherical nanoparticles with maximum number of particles having size around 30–50 nm. These nanoparticles were thoroughly characterized and employed as a catalyst for hydrogen production using hydrolysis of sodium borohydride (NaBH4). The effect of initial concentration of NaBH4, pH and temperature of solution on the rate of hydrogen production was investigated. Nickel nanoparticles exhibits first order reaction with respect to NaBH4 concentration at elevated temperatures. After hydrolysis, the nickel nanoparticles showed presences of B–O and B–OH species on the nickel surface. The catalyst was found to be stable during 5 sequential cycles of test.

DEM simulation of the pullout behavior of geogrid-stabilized ballast with the optimization of the coordination between aperture size and particle diameter

Based on the well-established constitutive models and particular configurations used in the discrete element method (DEM) simulation of the geogrid-stabilized ballast system, this paper presents the pull-out behavior of a triangular geogrid embedded in ballast under special consideration of the particle size. A representative particle size that equals to the diameter of the inscribed circle of the triangular aperture was selected to visualize the axial force distribution and the interface responses regarding the contact force. Meanwhile, fabric anisotropy on the normal component of contact force was introduced to explain the development of macroscopic strength. Results show that the first transverse rib makes the most contribution to the pull-out force. The V-shaped strong contact force chains were mainly grown in the geogrid-ballast substantial interaction region R1, and this interaction mode is not affected by particle size. Moreover, the maximum number of particles trapped in an aperture, Nmax, is used as the quantized indicator for numerical pull-out tests on 6 controlled conditions, and results unveil that the optimal reinforcement can be achieved when Nmax = 2, by evaluating the pull-out resistance, the interlocking effect, the energy dissipation, and the volumetric response.

Fine-Grained Concrete with Nanodispersed Silica Additive

The effect of the modifying nanodispersed silica (NS) additive, obtained by the polycondensation method, on the properties of fine-grained concrete (FGC) is studied. It is revealed that the dependence of the NS-additive particle size on its age is extreme. The maximum number of particles of up to 100 nm in the additive is observed at the age of 10 days, and then their number decreases. However, it affects the FGC strength little even after 30 days of the additive storage. It is established that the NS-additive could be most effectively used with 0.23% of an active silica concentration and pH 4.1 in combination with S-3. At that, the porosity declines from 17.5 to 12.9% and the pore diameter diminishes from 3.171 to 0.689 μm. It leads to an increase in the compressive strength by 2 times and a decrease in water absorption by 1.6 times as compared to the control composition without additives. An increase in the frost resistance of the modified fine-grained concrete to F250 is recorded; it occurs due to a decrease in porosity at portlandite binding with amorphous silica additives into low-basic calcium hydrosilicates.

Integrating Simulation and Numerical Analysis in the Evaluation of Generalized Stochastic Petri Nets

The standard existing performance evaluation methods for discrete-state stochastic models such as Petri nets either generate the reachability graph followed by a numerical solution of equations or use some variant of simulation. Both methods have characteristic advantages and disadvantages depending on the size of the reachability graph and type of performance measure. This article proposes a hybrid performance evaluation algorithm for the steady-state solution of Generalized Stochastic Petri Nets that integrates elements of both methods. It automatically adapts its behavior depending on the available size of main memory and number of model states. As such, the algorithm unifies simulation and numerical analysis in a joint framework. It is proved to result in an unbiased estimator whose variance tends to zero with increasing simulation time. The article extends earlier results with an algorithm variant that starts with a small maximum number of particles and increases them during the run to increase the efficiency in cases that are rapidly solved by regular simulation. The algorithm’s applicability is demonstrated through case studies, including an example where it outperforms the standard methods.

On the parametrization of the distributions of depth of shower maximum of ultra-high energy extensive air showers

The distribution of depth in which a cosmic ray air shower reaches its maximum number of particles (Xmax) is studied and parametrized. Three functions are studied for proton, carbon, silicon, and iron primary particles with energies ranging from 1017 eV to 1020 eV for three hadronic interaction models: EPOS-LHC, QGSJetII.04, and Sibyll2.3c. The function which best describes the Xmax distribution of a mixed composition is also studied. A very large number of simulated showers and a detailed analysis procedure are used to guarantee negligible effects of undersampling and of fitting in the final results. For the first time, a comparison of several functions is presented under the same assumption with the intention of selecting within them the best functional form to describe the Xmax distribution. The Generalized Gumbel distribution is shown to be the best option among the options for a general description of all cases. The Log-normal distribution is also a good choice for some cases while the Exponentially Modified Gaussian distribution has shown to be the worst choice in almost all cases studied. All three functions are parametrized as a function of energy and primary mass.

Methods to measure the cosmic-ray composition with the Auger Engineering Radio Array

The mass composition of ultra-high-energy cosmic rays plays a key role in the understanding of the origins ofthese rare particles. A composition-sensitive observable is the atmospheric depth at which the air shower reaches the maximum number of particles (Xmax). The Auger Engineering Radio Array (AERA) detects the radio emission inthe 30-80 MHz frequency band from extensive air showers with energies larger than 1017 eV. It consists of more than 150 autonomous radio stations covering an area of about 17 km2. From the distribution of signals measured by the antennas, it is possible to estimate Xmax. In this contribution three independent methods for the estimation of Xmax will be presented.

Simple Stochastic Model of Multiparticle Battery Electrodes Undergoing Phase Transformations

Author(s): Bartelt, NC; Li, Y; Sugar, JD; Fenton, K; Kilcoyne, ALD; Shapiro, DA; Tyliszczak, T; Chueh, WC; El Gabaly, F | Abstract: Incorporation of ions into battery electrodes can lead to phase transformations. When multiparticle phase-transforming electrodes charge or discharge, two processes must occur in each particle: the new phase must nucleate, and then grow until the particle is fully charged or discharged. A fundamental question is which of these two processes is rate limiting. Here we construct a simple stochastic model that shows how the relative rate of nucleation compared with growth determines the particle state-of-charge distributions in the electrode. We find that the number of particles that are partially charged at any time increases as the relative nucleation rate increases. The maximum number of particles that are actively charging occurs just before the time when the first particles are becoming completely charged. By comparing measured state-of-charge distributions with the model, we determine the relative rate of nucleation. We apply this procedure to measurements of the evolution of particles in LiFePO4 cathodes and show we can account for the particle state-of-charge distribution as a function of the electrode state of charge.