Different Types Of Collisions Research Articles

Segregation in binary and polydisperse stirred media mills and its role on grinding effectiveness

Most industrial vertical stirred mills contain a non-uniform set of grinding media sizes. However, this fact is often ignored in simulations, which mostly use monodispersed media. The paper explores the fundamental dynamics of vertical mills when using multiple sizes of grinding media, by using DEM simulation. Our results suggest that by including both large and small media, one may be able to optimise its performance in several manners. The energy going into the contacts can be increased by including a second size, leading to more effective grinding. Including smaller media can also reduce the power draw of the mill, increasing the efficiency and sustainability of the mill. Finally, the natural segregation between different sizes creates different types of collision which grind different particle sizes more effectively. Segregation leads to smaller media at the bottom, so continuous processes can be optimised for fine grinding by feeding from the top, where the larger media are. This further enables control of the resulting product specifications.

RetroV2X: A new vehicle-to-everything (V2X) paradigm with visible light backscatter networking

The Vehicle-to-Everything (V2X) technology has become essential with the increasing interest in intelligent transportation systems. It connects multiple vehicles and infrastructure by digitizing road traffic signs, signals, and other facilities and arranging sensing devices. However, conventional V2X solutions, such as Celluar Vehicle-to-Everything (C-V2X), have been slow to deploy due to their high cost, external power requirement, and dependence on Internet backhaul connectivity. Recently, Visible Light Backscatter Communication (VLBC) technology has emerged as a promising solution to overcome the practical issues of conventional V2X technologies. This paper presents RetroV2X, a protocol designed to support a networked VLBC-based V2X system that facilitates the transmission of road sensory data between vehicles and road infrastructure. We have designed several mechanisms, including backoff, virtual ID assignment, and excitatory carrier sensing, to handle different types of collisions, namely downlink, synchronous uplink, and asynchronous uplink collisions. Overhear and relay mechanisms are also designed to improve the performance at high vehicle densities. Our evaluation demonstrates that RetroV2X is capable of meeting the needs of V2X applications in typical rural road, town road, and highway scenarios with varying road sign densities, vehicle densities, and velocities.

A comparative study of collision types between automated and conventional vehicles using Bayesian probabilistic inferences

Introduction: Automated vehicle (AV) technology is a promising technology for improving the efficiency of traffic operations and reducing emissions. This technology has the potential to eliminate human error and significantly improve highway safety. However, little is known about AV safety issues due to limited crash data and relatively fewer AVs on the roadways. This study provides a comparative analysis between AVs and conventional vehicles on the factors leading to different types of collisions. Method: A Bayesian Network (BN) fitted using the Markov Chain Monte Carlo (MCMC) was used to achieve the study objective. Four years (2017–2020) of AV and conventional vehicle crash data on California roads were used. The AV crash dataset was acquired from the California Department of Motor Vehicles, while conventional vehicle crashes were obtained from the Transportation Injury Mapping System database. A buffer of 50 feet was used to associate each AV crash and conventional vehicle crash; a total of 127 AV crashes and 865 conventional vehicle crashes were used for analysis. Results: Our comparative analysis of the associated features suggests that AVs are 43% more likely to be involved in rear-end crashes. Further, AVs are 16% and 27% less likely to be involved in sideswipe/broadside and other types of collisions (head-on, hitting an object, etc.), respectively, when compared to conventional vehicles. The variables associated with the increased likelihood of rear-end collisions for AVs include signalized intersections and lanes with less than 45 mph speed limit. Conclusions: Although AVs are found to improve safety on the road in most types of collisions by limiting human error leading to vehicle crashes, the current state of the technology shows that safety aspects still need improvement.

Dynamics of degenerate and nondegenerate solitons in the two-component nonlinear Schrödinger equations coupled to Boussinesq equation

The paper studies the dynamics of degenerate and nondegenerate bright solitons and their collisions in the two-component nonlinear Schrödinger equations coupled to Boussinesq equation. The degenerate solitons that have only single-hump profiles, exhibit both elastic and inelastic collisions, and their velocities are identical in the two short wave (SW) components and in the long wave (LW) component. The nondegenerate single solitons have two different forms: one of them has double- or single-hump profiles and identical velocities in all SW and LW components, and the other one only admits single-hump profiles and has unequal velocities in the two SW components. The collisions of nondegenerate solitons cannot result in the redistribution of soliton intensities. Three different types of collisions of nondegenerate two-soliton solutions are studied in detail.

Industrial internet of things-driven storage location assignment and order picking in a resource synchronization and sharing-based robotic mobile fulfillment system

In this paper, we intend to address the value creation of utilizing the Industrial Internet of Things (IIoT)-driven resource synchronization and sharing-based robotic mobile fulfillment system (RMFS) to enhance the overall operational effectiveness and efficiencies during information transfer and synchronization of resources. With the advent of IIoT, a graph theory-based heuristic under the multi-deep RMFS is used for computing the shortest path. A-star, Dijkstra, and genetic heuristic algorithms are applied for comparison. A simulation with a consideration of the different types of collisions is conducted for different algorithms. By providing a new three-tier IIoT architecture which includes the suppliers, RMFS, and the disposal center, a model is developed with different storage location assignment rules and strategies under the particular parties to minimize the operation costs. IIoT enables resource synchronization and information sharing, and the path will be generated under different order scenarios with different algorithms. The results show that different storage assignment rules and strategies may lead to 30% cost differences compared to the company’s current practice with random storage.

A Comparative Structural Analysis of Four Radiosonde Models

Abstract In this study, we first performed a comprehensive structural analysis of four models of radiosondes (devices intended for use as the meteorological probe of a sounding balloon) manufactured by three different companies – Graw, Vaisala and Meteomodem. The radiosondes were disassembled for visual inspection and manual measurement, three-dimensional computed tomography images were taken of their inner structure, and the outer shapes of the radiosondes were scanned with a structured-light three-dimensional scanner. The structural properties of the radiosondes thus identified were then compared to one other, based on which the Meteomodem M10 was ranked as the least harmful in a potential collision. Next, the Meteomodem M10 radiosonde was used in collision tests with a heavy target and with a pumpkin model, in order to evaluate the possible damage caused by and to the radiosonde in different types of collisions.

Multiplicity characteristics of target fragments and shower particles with noninteracting projectile nucleons emitted in 84Kr–Em interaction at 1 A GeV

In this article, we have focused on the multiplicity distributions of the target fragments and shower particles for the events released from the interactivity of the 84 Kr36 –Em at 1 A GeV. We have also focused on the variation among the target fragments and shower particles with emerged projectile fragments. In the present analysis to distinguish the type of collision, we have used different parameter which is total charge Q of the outgoing projectile fragments (i.e. the projectile fragments emitted in forward cone θ c ≤ 30 ) or total charge of noninteracting projectile nucleons, in place of impact parameter. This new parameter is playing an important role in classifying the different types of collisions, especially in peripheral collisions. The results of the current analysis are also verified with recent experimental observations and found to be consistence.

Statistics of collision parameters computed from 2D simulations

ABSTRACTThere are two popular ways to speed up simulations of planet formation via increasing the collision probability: (i) confine motion to 2D, (ii) artificially enhance the physical radii of the bodies by an expansion factor. In this paper, I have performed 100 simulations each containing 104 interacting bodies and computed the collision parameters from the results of the runs. Each run was executed for a lower and a higher accuracy parameter. The main goal is to determine the probability distribution functions of the collision parameters and their dependence on the expansion factor. A simple method is devised to improve the determination of the collision parameters from the simulation data. It was shown that the distribution of the impact parameter is uniform and independent of the expansion factor. For real collisions, the impact velocity is greater than 1 mutual escape velocity, a finding that can be explained using the two-body problem. The results cast some doubts on simulations of the terrestrial planets’ final accretion that have assumed merge. Collision outcome maps were created adopting the fragmentation model of recent studies to estimate the number of different types of collisions. A detailed comparison with earlier works indicates that there are similarities as well as significant differences between the different works. The results indicate that as the planetary disc matures and the masses of the bodies differ progressively than the majority of collisions lead to mass growth either via partial accretion or via graze-and-merge collision.

Bubbles interactions in fluidized granular medium for the van der Waals hydrodynamic regime

This paper investigates the fluidized granular materials (FGM) with the van der Waals normal form (VDWF) under the effects of friction and viscosity. The system of macroscopic balance is presented, including the mass, momentum, and energy equations of local densities. For two different types of collisions, elastic and inelastic collisions, analytical solutions of the nonlinear PDEs governing the granular model are investigated using the hydrodynamic equations for granular matter motion. The integrability of the proposed model is analyzed by applying the Painleve analysis. Moreover, the Backlund transformation (BT) is established using the Painleve truncation expansion. New traveling wave solutions of the VDWF within FGM are obtained by using the BT, tanh function, Jacobi elliptic function methods to study the phase separation phenomenon. As two pairs of rarefaction and shock waves emerge and travel away giving the appearance of bubbles, the resulting solutions of the proposed model show a behavior similar to those found in the molecular dynamic simulations. The dispersion relation and their properties to the model equation are investigated. Besides, stability analysis of the VDWF in its ODE form is demonstrated using the phase portrait classifications. Finally, using two- and three-dimensional graphics for seeking model solutions under the influence of friction and viscosity, qualitative agreements with previous related works are shown.

Spare zone based hierarchical motion coordination for multi-AGV systems

Automated guided vehicles (AGVs) are widely used in various material handling systems due to their high efficiency and low cost, particularly in warehouses. However, deadlock resolution among vehicles is still a thorny issue. Many algorithms re-plan motion paths to avoid deadlocks resulting in greatly increasing the computational complexity, while other deadlock resolution algorithms in which vehicles have fixed paths are less efficient. This paper proposes a spare zone based hierarchical (SZH) motion coordination algorithm supporting time-efficient collision-and-deadlock resolution among vehicles. Unlike previous deadlock resolution methods in which the vehicles can change their paths to avoid deadlocks at any time, SZH avoids deadlocks just by locally adjusting their paths in a decentralized manner. The introduction of a spare zone mechanism ensures reliable resolution of different types of collision and deadlocks while achieving high time efficiency. The allocation of spare zones for each vehicle before performing their missions guarantees that there exist enough free zones to which the vehicles taking part in deadlocks can temporary departs from their current path to avoid deadlocks. In order to improve the efficiency, the vehicle’s spare zones are updated as soon as the vehicle arrives at a zone. The algorithm is realized based on a hierarchical strategy, where the top layer considers the allocation and update of spare zones, while the bottom layer considers the coordination among vehicles within two zones. Extensive simulation results demonstrate the feasibility and efficiency of the proposed motion coordination algorithm.

Understanding Newton’s cradle. II: exploring a real cradle

Newton’s cradle is a well-known physics toy that is commonly used by teachers to demonstrate conservation laws in mechanics. It can also be used to investigate the physics of colliding objects, by recording motion of the balls on video film. Various experiments are described using 3-ball and 5-ball cradles, showing how different types of collision can be investigated depending on whether the balls are touching or separated. The sequence of collisions was examined as a function of time, with the surprising observation that very small gaps between the balls, invisible on video film, make a significant difference to the collision dynamics. Additional experiments illustrate the effects of changes in ball stiffness and the mass of the middle ball and provide an introduction for students and teachers into possible research projects. Each experiment is illustrated with a supplementary video.

Kinetic modeling of multiphase flow based on simplified Enskog equation

A new kinetic model for multiphase flow was presented under the framework of the discrete Boltzmann method (DBM). Significantly different from the previous DBM, a bottom-up approach was adopted in this model. The effects of molecular size and repulsion potential were described by the Enskog collision model; the attraction potential was obtained through the mean-field approximation method. The molecular interactions, which result in the non-ideal equation of state and surface tension, were directly introduced as an external force term. Several typical benchmark problems, including Couette flow, two-phase coexistence curve, the Laplace law, phase separation, and the collision of two droplets, were simulated to verify the model. Especially, for two types of droplet collisions, the strengths of two non-equilibrium effects, $\bar{D}_2^*$ and $\bar{D}_3^*$, defined through the second and third order non-conserved kinetic moments of $(f - f ^{eq})$, are comparatively investigated, where $f$ ($f^{eq}$) is the (equilibrium) distribution function. It is interesting to find that during the collision process, $\bar{D}_2^*$ is always significantly larger than $\bar{D}_3^*$, $\bar{D}_2^*$ can be used to identify the different stages of the collision process and to distinguish different types of collisions. The modeling method can be directly extended to a higher-order model for the case where the non-equilibrium effect is strong, and the linear constitutive law of viscous stress is no longer valid.

Post-collisional mafic magmatism: Record of lithospheric mantle evolution in continental orogenic belt

In order to better understand the role of post-collisional mafic magmatism at convergent plate boundaries in revealing the earth’s evolution, this paper has systematically summarized the research history of post-collisional mafic magmatism, different types of collision and their influence on the nature of orogenic mantle, the concept and implication of post-collisional magmatism, and the relationship between post-collisional mafic magmatism and orogenic mantle evolution and mineralization. Post-collisional mafic igneous rocks are not only the direct records for studying the nature and evolution of orogenic mantle, but also the important carriers for regional mineralization. However, the type and quantity of the crustal materials involved in modifying the overlying lithospheric mantle during collisional orogeny, the process and mechanism of such modification, and the major control factors and mechanism of mafic magmatism-related mineralization during the post-collisional period are the main contents and direction of future researches in this field. Therefore, the study of post-collisional mafic magmatism is of significant implications for developing the theory of plate tectonics.

Assessing risk factors associated with urban transit bus involved accident severity: a case study of a Middle East country

While buses are a safe form of transport in developed countries, developing countries like Iran face significant safety concerns regarding buses. Nevertheless, few studies have examined the factors associated with the number and severity of bus crashes. The present study investigates the underlying risk factors associated with the severity of urban transit bus accidents in Mashhad, Iran, by estimating a binary logit model. Data for the analysis are retrieved from Mashhad Bus Company Safety Office between the years 2014 and 2016. Accident severity is divided into PDO (Property Damage Only) and injury or fatal categories, and the effect of several risk factors on the probability of bus accidents with higher severity is examined. Results from this study indicate that bus accident severity is positively associated with the speed limit and the presence of vulnerable road users as the other involved party. Furthermore, bus accident occurrence at bus stops and roundabouts decreases the probability of injury or fatality in comparison to the roadway segments. Focusing on the accident type, in comparison to single-vehicle accidents, collisions with other vehicles decrease the probability of injury or fatal accidents for buses. Among different types of collisions, angle and sideswipes are the most and least probable types of crashes to result in injury or fatality, respectively. Model results show that time-related variables, median presence, bus age, and bus model are not significantly associated with the bus accident severity. The results of this study provide a relatively comprehensive picture of bus safety in Mashhad.

Identification of differential risk hotspots for collision and vehicle type in a directed linear network

Traffic accidents can take place in very different ways and involve a substantially distinct number and types of vehicles. Thus, it is of interest to know which parts of a road structure present an overrepresentation of a specific type of traffic accident, specially for some typologies of collisions and vehicles that tend to trigger more severe consequences for the users being involved.In this study, a spatial approach is followed to estimate the risk that different types of collisions and vehicles present in the central area of Valencia (Spain), considering the accidents observed in this city during the period 2014–2017. A directed spatial linear network representing the non-pedestrian road structure of the area of interest was employed to guarantee an accurate analysis of the point pattern.A kernel density estimation technique was used to approximate the probability of risk along the network for each collision and vehicle type. A procedure based on these estimates and the sample size locally available within the network was designed and tested to determine a set of differential risk hotspots for each typology of accident considered. A Monte Carlo based simulation process was then defined to assess the statistical significance of each of the differential risk hotspots found, allowing the elaboration of rankings of importance and the possible rejection of the least significant ones.

Effective-energy universality approach describing total multiplicity centrality dependence in heavy-ion collisions

The recently proposed participant dissipating effective-energy approach is applied to describe the dependence on centrality of the multiplicity of charged particles measured in heavy-ion collisions at the collision energies up to the LHC energy of 5 TeV. The effective-energy approach relates multihadron production in different types of collisions, by combining, under the proper collision energy scaling, the constituent quark picture with Landau relativistic hydrodynamics. The measurements are shown to be well described in terms of the centrality-dependent effective energy of participants and an explanation of the differences in the measurements at RHIC and LHC is given by means of the recently introduced hypothesis of the energy-balanced limiting fragmentation scaling. A similarity between the centrality data and the data from most central collisions is proposed pointing to the central character of participant interactions independent of centrality. The findings complement our earlier studies of the similar midrapidity pseudorapidity density measurements extending the description to the full pseudorapidity range in view of the similarity of multihadron production in nucleon interactions and heavy-ion collisions.

Transverse momentum distribution of charged hadrons based on wounded quark model

In nucleus-nucleus collisions, new particles are produced mainly through strong interactions among the constituents of the QCD medium. The search of a unified phenomenological model to understand this production mechanism is one of the main motivation behind the heavy ion experiments. A vast variety of data coming from nucleus-nucleus collision experiments put a stringent constraint on the particle production models. A unified and proper model must satisfy the various data regarding pseudorapidity distributions, transverse energy density distributions, transverse momentum distributions with respect to control parameters in different types of collisions at various energies simultaneously. Recently we proposed a new version of wounded quark model (WQM) which actually satisfies many points of this criteria. However, these kind of static initial model conditions have problem in calculating the transverse momentum distributions of charged hadrons. In this article, we have used the important ingredients of WQM like number of wounded quarks and number of quark-quark collisions to fit the transverse momentum spectra of charged hadrons. Based on the assumption of different mechanisms at different regions, i.e. different mechanisms for soft $ p_{T}$ and hard momentum part, we have proposed a parameterization made of two functions to calculate the transverse momentum spectra in different collisions at different energies ranging from higher RHIC to LHC. We hope that this study along with our recent work on WQM will become a more suitable choice as unified model for particle production in strong interaction, instead of wounded nucleon model.

Effect of operating condition changes on the collisional environment in a SAG mill

Discrete Element Method (DEM) modelling of the motion of balls and rocks in grinding mills allows the flow structure and material transport to be understood. It also provides information on the energy dissipated in every collision of resolved particles (which here are 25–200 mm). These energy dissipation events control the nature and intensity of the grinding. This grinding environment can be characterised by the collisional energy spectra. In this paper we explore the quantitative structural change in the collisional environment in SAG (Semi-Autogenous Grinding) mill as measured by the energy spectra predicted using DEM. The simulations show that increasing mill speed has little effect the collision energy distribution between the different types of collisions. Three other mill operating conditions (separately) all lead to decreases in impact breakage and increases in grinding activity for decreasing lifter height, increasing charge fill level, and decreasing rock-to-ball ratio.

Kinetic Simulation Study of Electron Holes Dynamics During Collisions of Ion-Acoustic Solitons

Ion acoustic (IA) solitons are accompanied by vortex-shaped nonlinear structures (e.g., hollows, plateaus, or humps) in the electron distribution function, called electron holes, portraying trapped electrons. These structures appear as charged flexible clouds (shielded by the background plasma) in the phase space with their own inertia, depending on the number of trapped electrons. According to simulation studies, electron holes tend to merge in pairs until one accumulative hole remains in the simulation box. This tendency has been analytically and qualitatively explained in the frame of the energy conservation principle. However, electron holes accompanying IA solitons should not merge due to the stability of IA solitons against mutual collisions. In this report based on a fully kinetic simulation approach, detailed study of the collisions of IA solitons reveals the behavior of electron holes under these two conflicting predictions, i.e., stability against mutual collisions and merging tendency. Four main results are reported here. First, we find that among the three different types of collisions possible for electron holes, just two of them happen for electron holes accompanying IA solitons. We present different collisions, e.g., two large/small and large versus small holes, to cover all these three different types of collisions. Second, we show that although electron holes merge during collisions of IA solitons, the stability of IA solitons forces the merged hole to split and form new electron holes. Third, we reveal that holes share their trapped population during collisions. Postcollision holes incorporate some parts of the oppositely propagating before-collision holes. Finally, it is shown that the newly added population of trapped electrons goes through a spiral path inside the after-collision holes because of dissipative effects. This spiral is shown to exist in the early stage of the formation of the holes in the context of the IA soliton dynamics.

Small-N collisional dynamics – III: The battle for the realm of not-so-small-N

In this paper, the third in the series, we continue our study of combinatorics in chaotic Newtonian dynamics. We study the chaotic four-body problem in Newtonian gravity assuming finite-sized particles, and we focus on interactions that produce direct collisions between any two stars. Our long-term goal is to construct an equation that gives the probability of a given collision event occurring over the course of the interaction, as a function of the total encounter energy and angular momentum as well as the numbers and properties of the particles. In previous papers, we varied the number of interacting particles and the distribution of particle radii, for all equal mass particles. Here, we focus on the effects of different combinations of particle masses. We develop an analytic formalism for calculating the time-scales for different collision scenarios to occur. Our analytic time-scales reproduce the simulated time-scales when gravitational focusing is included. We present a method for calculating the relative rates for different types of collisions to occur, assuming two different limits for the particle orbits; radial and tangential. These limits yield relative collision probabilities that bracket the probabilities we obtain directly from numerical scattering experiments, and are designed to reveal important information about the (time-averaged) trajectories of the particles as a function of the interaction parameters. Finally, we present a Collision Rate Diagram (CRD), which directly compares the predictions of our analytic rates to the simulations and quantifies the quality of the agreement. The CRD will facilitate refining our analytic collision rates in future work, as we expand in to the remaining parameter space.