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Copyright of Clean Coal Technology is the property of Clean Coal Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Transactions of Nanjing University of Aeronautics & Astronautics is the property of Editorial Department of Journal of Nanjing University of Aeronautics & Astronautics and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Quantum collision models normally consist of a system interacting with a set of ancillary units representing the environment. While these ancillary systems are usually assumed to be either two level systems or harmonic oscillators, in this work we move further and represent each ancillary system as a structured system, i.e. a system made out of two or more subsystems. We show how this scenario modifies the kind of master equation that one can obtain for the evolution of the open systems. Moreover, we are able to consider a situation where the ancilla state is thermal yet has some coherence. This allows the generation of coherence in the steady state of the open system and, thanks to the simplicity of the collision model, this allows us to better understand the thermodynamic cost of creating coherence in a system. Specifically, we show that letting the system interact with the coherent degrees of freedom requires a work cost, leading to the natural fulfillment of the first and second law of thermodynamics without the necessity of ad hoc formulations. [ABSTRACT FROM AUTHOR]

A quantum system interacting with a multipartite environment can induce redundant encoding of the information of a system into the environment, which is the essence of quantum Darwinism. At the same time, the environment may scramble the initially localized information about the system. Based on a collision model, we mainly investigate the relationship between information scrambling in an environment and the emergence of quantum Darwinism. Our results show that when the mutual information between the system and environmental fragment is a linear increasing function of the fragment size, the tripartite mutual information (TMI) is zero, which can be proved generally beyond the collision model; when the system exhibits Darwinistic behavior, the TMI is positive (i.e., scrambling does not occur); when we see the behavior of an "encoding" environment, the TMI is negative (i.e., scrambling occurs). Additionally, we give a physical explanation for the above results by considering two simple but illustrative examples. Moreover, depending on the nature of system and environment interactions, it is also shown that the single qubit and two-qubit systems behave differently for the emergence of quantum Darwinism, and hence the scrambling, while their relationship is consistent with the above conclusion. [ABSTRACT FROM AUTHOR]

As a comprehensive research platform integrating machine vision and motion control, the research of table tennis robot has always attracted much attention. The complexity and high real - time of its mechanical mechanism, visual algorithm and motion control are important factors hindering the development of table tennis robot. In order to improve the competitive ability of table tennis robot, it is necessary to solve the problems of table tennis rotation measurement, accurate prediction of movement trajectory and selection of hitting strategy, which is also the focus of the research of table tennis robot in recent years. Based on the research progress in this field in recent years, this study focuses on the research results of table tennis robot vision core algorithm and ball return core algorithm, analyzes the advantages and disadvantages of different algorithms and prospects the future research trend, so as to provide a reference for the research and design of table tennis robot. [ABSTRACT FROM AUTHOR]

Micron-sized particles are prone to deposit on smooth surfaces. A micron-sized particle collision-deposition model including the effects of electrostatic forces, integrated with the factors of particle size, material properties, elastic–plastic deformation, particle charging, surface roughness, and van der Waals forces, is proposed. The effects of the electrostatic forces on the critical deposition velocity, collision duration, and coefficient of restitution (COR), which is the ratio of particle velocity after and before the collision, are investigated for 1–20 μm sand particles colliding with glass, steel, and aluminum alloy surfaces. The results show that the electrostatic forces of sand particles are approximately 106–108 times their gravity and increase the impact duration. Moreover, these forces increase the critical deposition velocity by 2.32–6.89% for the glass surface and decrease the COR by 0.6–3.5% for the three surfaces, while the particle size is below 20 μm and the roughness is 1 nm. The electrostatic forces ranked from the maximum to the minimum are those of the aluminum alloy, steel, and glass surfaces for the same particle size and surface roughness. The developed model can perfect the theory of particle flow and gas-particle two-phase flow. [ABSTRACT FROM AUTHOR]

The introduction of more automation into our vehicles is increasing our ability to avoid or mitigate the effects of collisions. Early systems could brake when a likely collision was detected, while more advanced systems will be able to steer to avoid or reconfigure a collision during the same circumstances. This paper addresses how the post-impact motion of an impacted vehicle could be included in the decision-making process of severity minimisation motion planning. A framework is proposed that builds on previous work by the authors, combining models from motion planning, vehicle dynamics, and accident reconstruction. This framework can be configured for different contexts by adjusting its cost function according to relevant risks. Simulations of the unified system are carried out and analysed from the perspective of vehicle model complexity and collision parameters sensitivity. Additionally, effects are highlighted concerning different modelling decisions, with respect to vehicle dynamics models and collision models, that are important to consider in further research. [ABSTRACT FROM AUTHOR]

To research the muzzle response characteristics of marching small unmanned ground vehicles with small arms (SUGVsSA), this paper establishes a launch dynamic model of an SUGVSA by considering various nonlinear features. According to the mechanism characteristics, the improved Lankarani–Nikravesh algorithm is adopted to define the projectile–barrel coupling effect and trunnion–bearing clearance collision behaviour; additionally, the collision models of bearing race and worm gear are both established by the Hertz contact theory. Muzzle vibration experiments based on the combination of high-speed photogrammetry and inertial measurement systems are performed to verify the accuracy of the SUGVSA launch dynamic model. Three-dimensional (3D) road shell models are established by using the harmonic superposition method and then discretized and integrated with the Bekker soil mechanical properties to generate a flexible 3D road surface. The muzzle response characteristics of the SUGVSA under various working conditions are calculated and analysed. The results indicate that the muzzle response characteristics are related to the road shell, soil type, and driving speed, and they present many regularities. The initial firing angle has no obvious effect on the muzzle response. If the clearance between the trunnion and bearing increases, the muzzle elevation angular vibration intensifies when the SUGVSA moves. The muzzle aim point deviation caused by the flexible barrel is small, and it is not the main factor affecting the shooting accuracy of marching SUGVsSA. The muzzle vertical stabilizer can reduce the muzzle disturbance effectively, but the stabilization effect based on the PID system is not ideal. It is necessary to propose a more robust control algorithm to improve the muzzle stabilization accuracy. [ABSTRACT FROM AUTHOR]

The effect of environmental coherence on bipartite and tripartite quantum entanglements using quantum collision models is studied. In the collision model, an open quantum system of two qubits indirectly interacts with the reservoir via auxiliary qubits. The reservoir is modeled as a collection of initially uncorrelated qubits prepared in an identically nonthermal state. It is shown that the coherence of the nonthermal reservoir contributes to the generation and protection of entanglement. It is found that adding coherence to the initial state of the reservoir qubit can significantly enhance the steady‐state entanglement of the system, and the presence of coherence in the reservoir allows steady‐state entanglement to be obtained in a higher temperature region. [ABSTRACT FROM AUTHOR]

To establish a collision model of wheat grains impacting a force plate with a piezoelectric sensor, and to investigate the influence of the elastic recovery coefficient on the sensor's detection accuracy during the collision process, this study employed object kinematic principles to construct a wheat elastic recovery coefficient measurement device. This device ascertains the elastic properties of wheat during collisions and determines the elastic recovery coefficient of the wheat collision model. The wheat variety Jinan No. 17 was selected for testing, and the effects of the contact material, grain drop height, material thickness, and grain moisture content on the collision recovery coefficient during the collision process were analyzed through single-factor and multi-factor experiments. The experimental results demonstrate that the collision recovery coefficient of wheat grains increases with the stiffness of the collision materials for different materials. The grain recovery coefficient of wheat exhibits a downward trend with increasing falling height and moisture content, while it tends to rise as the material thickness increases. Data analysis and comparison reveal that, given the determination of the collision material, the moisture content of wheat exerts the most significant effect on the elastic recovery coefficient, followed by material thickness, while the influence of falling height is less pronounced. The findings of this study can provide data support for simulation testing and product design of wheat combine harvester cleaning screen body mechanisms and wheat seeders. [ABSTRACT FROM AUTHOR]

Copyright of Chinese Journal of Computational Mechanics / Jisuan Lixue Xuebao is the property of Chinese Journal of Computational Mechanics Editorial Office, Dalian University of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Ordnance Equipment Engineering is the property of Chongqing University of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this study, we show that as a result of weak interaction of different information environments structured with a single probe qubit, these environments can perform binary classification of the information they contain. In this way, we refer to these environments as quantum information baths because they consist of sequences of identical qubits in certain pure quantum states. A micro-maser like master equation has been developed to clearly describe the system dynamics analytically and the quantum states of different information reservoirs. The model can also be treated as a quantum neuron, due to the single-qubit probe that makes a binary decision depending on the reservoir parameters in its steady state. The numerical results of the repeated interaction process based on the divisibility and additivity of the quantum dynamic maps are compared with the analytical results. Besides being a single quantum classifier, the model we present can also serve as a basic unit of a quantum neural network within the framework of the dissipative model of quantum computing.

An efficient algorithm to simulate dynamics of open quantum system is presented. The method describes the dynamics by unraveling stochastic wave functions converging to a density operator description. The stochastic techniques are based on the quantum collision model. Modeling systems dynamics with wave functions and modeling the interaction with the environment with a collision sequence reduces the scale of the complexity significantly. The algorithm developed can be implemented on quantum computers. We introduce stochastic methods that exploit statistical characteristics of the model such as Markovianity, Brownian motion, and binary distribution. The central limit theorem is employed to study the convergence of distributions of stochastic dynamics of pure quantum states represented by wave vectors. By averaging a sample of functions in the distribution we prove and demonstrate the convergence of the dynamics to the mixed quantum state described by a density operator. [ABSTRACT FROM AUTHOR]

The common reservoir can cause some unique effects, such as dark state and steady-state coherence, which are extensively studied in the dynamics of open quantum system. In this work, by means of collision model, we explore features of quantum thermodynamics induced by common reservoirs. We first construct general formulations of thermodynamic quantities for the system consisting of N coupling subsystems embedded in M common thermal reservoirs. We confirm the existence of nonlocal work due to simultaneous interactions of subsystems with the common reservoirs resembling what is found for nonlocal heat. With a system of two coupled qubits in a common reservoir, we show that steady-state currents could emerge even when interactions of individual subsystems and the reservoir fulfill strict energy conservation. We also exhibit the effect of dark state on the steady-state currents. We then examine relations between the work cost, the system's nonequilibrium steady-state and the extractable work. In particular, we find that in the presence of dark state, the work cost is only related to the coherence generated in the dynamical evolution but not to the one contributed by the initial dark state of the system. We also show the possible transformation of coherence into useful work in terms of ergotropy. We finally examine the scale effect of reservoirs and show that the increase of the number of involved reservoirs need more work to be costed and meanwhile can produce more coherence so that more ergotropy can be extracted. The obtained features contribute to the understanding of thermodynamics in common reservoirs and would be useful in quantum technologies when common reservoirs are necessary. [ABSTRACT FROM AUTHOR]

In recent years, quantum collision models, sometimes dubbed repeated interaction models, have gained much attention due to their simplicity and their capacity to convey ideas without resorting to technical complications typical of many approaches and techniques used in the field of open quantum systems. In this tutorial, we show how to use these models, highlighting their strengths and some technical subtleties often overlooked in the literature. We do this by deriving the Markovian master equation and comparing the standard collisional derivation with the standard microscopic one. We then use the collision model to derive the master equation of a two-level system interacting with either a bosonic or fermionic bath to give the reader a flavour of the real use of the model. [ABSTRACT FROM AUTHOR]

The high energy transfer efficiency of photosynthetic complexes has been a topic of research across many disciplines. Several attempts have been made in order to explain this energy transfer enhancement in terms of quantum mechanical resources such as energetic and vibration coherence and constructive effects of environmental noise. The developments in this line of research have inspired various biomimetic works aiming to use the underlying mechanisms in biological light harvesting complexes for the improvement of synthetic systems. In this article, we explore the effect of an auxiliary hierarchically structured environment interacting with a system on the steady-state heat transport across the system. The cold and hot baths are modeled by a series of identically prepared qubits in their respective thermal states, and we use a collision model to simulate the open quantum dynamics of the system. We investigate the effects of system-environment, inter-environment couplings and coherence of the structured environment on the steady state heat flux and find that such a coupling enhances the energy transfer. Our calculations reveal that there exists a non-monotonic and non-trivial relationship between the steady-state heat flux and the mentioned parameters. [ABSTRACT FROM AUTHOR]

Simulations of the powder jet in direct metal deposition (DMD) are often made with significant simplifications such as being incompressible, steady-state, or single-component, and do not provide explanation for the choice of parameters in the collision model. This work presents a coupled Computational Fluid Dynamics–Discrete Element Method model for the powder jet in DMD that considers all of the following features: compressibility effects, particle–wall and particle–particle collisions, turbulence, gas mixing, and melt pool boundaries. The goal of the simulation is to optimize the operating conditions and to predict the outcomes of experiments. After effective validation against experimental results, the effects of inlet gas, collision models and different boundary conditions in DMD have been comprehensively studied. It is demonstrated that gases with higher diffusivities, such as helium, are less effective shielding gases than those with lower diffusivities, such as argon. The increased wall temperature arising from the melt pool and track has little influence on the particle distribution. [Display omitted] • A coupled CFD-DEM model for powder flow in direct metal deposition is developed. • Particle flow distribution is largely determined by fluid velocity and particle properties. • Particle collision behavior is primarily dictated by coefficients of restitution and friction. • The melt pool temperature has little influence on the particle motion. [ABSTRACT FROM AUTHOR]

We study the steady-state thermodynamics of a cascaded collision model where two subsystems S 1 and S 2 collide successively with an environment R in the cascaded fashion. We first formulate general expressions of thermodynamics quantities and identify the nonlocal forms of work and heat that result from cascaded interactions of the system with the common environment. Focusing on a concrete system of two qubits, we then show that, to be able to unidirectionally influence the thermodynamics of S 2 , the former interaction of S 1 − R should not be energy conserving. We finally demonstrate that the steady-state coherence generated in the cascaded model is a kind of useful resource in extracting work, quantified by ergotropy, from the system. Our results provide a comprehensive understanding on the thermodynamics of the cascaded model and a possible way to achieve the unidirectional control on the thermodynamics process in the steady-state regime. [ABSTRACT FROM AUTHOR]

Quantum collision models have proved to be useful for a clear and concise description of many physical phenomena in the field of open quantum systems: thermalization, decoherence, homogenization, nonequilibrium steady state, entanglement generation, simulation of many-body dynamics, and quantum thermometry. A challenge in the standard collision model, where the system and many ancillas are all initially uncorrelated, is how to describe quantum correlations among ancillas induced by successive system-ancilla interactions. Another challenge is how to deal with initially correlated ancillas. Here we develop a tensor network formalism to address both challenges. We show that the induced correlations in the standard collision model are well captured by a matrix product state (a matrix product density operator) if the colliding particles are in pure (mixed) states. In the case of the initially correlated ancillas, we construct a general tensor diagram for the system dynamics and derive a memory-kernel master equation. Analyzing the perturbation series for the memory kernel, we go beyond the recent results concerning the leading role of two-point correlations and consider multipoint correlations (Waldenfelds cumulants) that become relevant in the higher-order stroboscopic limits. These results open an avenue for the further analysis of memory effects in collisional quantum dynamics. [ABSTRACT FROM AUTHOR]

In this study, we show that as a result of weak interaction of different information environments structured with a single probe qubit, these environments can perform binary classification of the information they contain. In this way, we refer to these environments as quantum information baths because they consist of sequences of identical qubits in certain pure quantum states. A micro-maser like master equation has been developed to clearly describe the system dynamics analytically and the quantum states of different information reservoirs. The model can also be treated as a quantum neuron, due to the single-qubit probe that makes a binary decision depending on the reservoir parameters in its steady state. The numerical results of the repeated interaction process based on the divisibility and additivity of the quantum dynamic maps are compared with the analytical results. Besides being a single quantum classifier, the model we present can also serve as a basic unit of a quantum neural network within the framework of the dissipative model of quantum computing. [ABSTRACT FROM AUTHOR]

The interaction between vertical offshore wind turbine (OWT) and sea ice with fluid is a complex process including local and global crushing of ice fragments and vibration of OWT. It is crucial to study the ice resistance of OWT structures considering the fluid-structure interaction (FSI). This article investigates a complete process of dynamic sea ice-monopile OWT interaction considering soil-structure interaction (SSI) and FSI effects. A fully coupled dynamic collision model of sea ice and OWT incorporating with the explicit non-linear collision tool ANSYS/LS-DYNA is proposed. The simulated ice loads in this study is verified by different simulation methods and international static ice force standards closely related to ice dynamic characteristic parameters. Then, the dynamic response and damage of the OWT structure during ice-structure interaction are studied using the fully interaction model with FSI coupling. The simulated ice force can produce a significant vibration response in the structure coupling with FSI due to occurrence of ice-induced resonance in the ice velocity range of 2.5–3.5 cm/s. Finally, the effect of fluid on the sea ice-OWT interaction in the initial velocity collision of sea ice is analyzed. FSI coupling can cause a certain level of collision hysteresis, accelerate the failure of sea ice breaking and reasonably reduce the energy of the structure.

To establish a collision model of wheat grains impacting a force plate with a piezoelectric sensor, and to investigate the influence of the elastic recovery coefficient on the sensor’s detection accuracy during the collision process, this study employed object kinematic principles to construct a wheat elastic recovery coefficient measurement device. This device ascertains the elastic properties of wheat during collisions and determines the elastic recovery coefficient of the wheat collision model. The wheat variety Jinan No. 17 was selected for testing, and the effects of the contact material, grain drop height, material thickness, and grain moisture content on the collision recovery coefficient during the collision process were analyzed through single-factor and multi-factor experiments. The experimental results demonstrate that the collision recovery coefficient of wheat grains increases with the stiffness of the collision materials for different materials. The grain recovery coefficient of wheat exhibits a downward trend with increasing falling height and moisture content, while it tends to rise as the material thickness increases. Data analysis and comparison reveal that, given the determination of the collision material, the moisture content of wheat exerts the most significant effect on the elastic recovery coefficient, followed by material thickness, while the influence of falling height is less pronounced. The findings of this study can provide data support for simulation testing and product design of wheat combine harvester cleaning screen body mechanisms and wheat seeders.

The current study introduces a new particle–particle collision model as well as a classical particle–wall collision model to simulate the process of bedload transport. Large eddy simulation and two-way coupling Lagrangian point–particle models also are applied. Flow conditions for all simulations are done based on previous experiments and four comparison cases are studied. The bedload function result obtained using this model agrees with the previous studies, which proves that the model is reasonable and effective in dealing with bedload transport in turbulent flow. Otherwise, failure to consider the particle–particle collision, Basset force, or Saffman lift force in the model lead to underestimating the bedload transport rate. [ABSTRACT FROM AUTHOR]

Aiming at the problems of poor risk identification ability and high false alarm rate in current vehicle collision warning technology, the self-adaptability of vehicle driver collision warning is proposed: Can consciousness recognition improve the warning accuracy? Construct an adaptive collision warning model, and quantify the impact of each vehicle's collision with an adaptive weight distribution method. The collision speed, the collision safety factor and the lateral offset related to the collision process are used as the weight distribution index to calibrate the model parameters. The maximum similarity recursive algorithm is used to estimate the characteristics of the current vehicle driving state. The maximum braking deceleration threshold is used to determine the degree of collision risk between the own vehicle and the following vehicle. The collision risk levels of the two workshops are divided into three levels: safety, critical value, and danger. The signal detection principle is adopted to modularize the initial information of the collision warning system, and the driving state assessment threshold adaptation category of the collision warning system is alarmed according to the actual situation. Experiments have verified that when the vehicle collision risk level is the critical value, the DR value of the model in this paper is 0.06 larger than the value of the NCM model, and it takes 3s-6s more time for the driver to take anti-collision and obstacle avoidance measures. Compared with the area under the ROC curve of the NCM model, the local algorithm has high warning accuracy and low false alarm rate. [ABSTRACT FROM AUTHOR]

In this study, a coupling rule based on Lattice Boltzmann Method (LBM), Immersed Boundary Method (IBM), and Discrete Element Method (DEM) was developed to simulate settling of particles in Newtonian liquid. The direct forcing IB-LBM, which was enhanced by the split-forcing technique, was utilized to account for fluid/solid interactions. Dynamic behavior of particles during collisions was evaluated by DEM, in which contact forces were computed based on overlap distances and relative velocity between two particles. The lubrication force was also included in equation of motions that allowed the coupled IB-LB-DEM to accurately account for the fluid film before collision. The hybrid model was verified by examining the freely falling of single and tandem circular particles in a vertical box. The particle-particle collision was included in the model and particular attention was given to the examination of the effects of collision parameters including restitution and friction coefficients on the particle sedimentation behavior. The transverse and longitudinal positions and velocities of two falling particles are compared for a wide range of physical parameters. Finally, free falling of 28 particles for two different friction coefficients were simulated to show capability of the new model for analyzing particulate flows. [ABSTRACT FROM AUTHOR]

In this work, we study effects of different types of system-reservoir interactions on work costs and operating regimes of thermal machines by considering a quantum system consisting of two subsystems embedded in both independent and common reservoirs. The model allows us to make a contrast between three configurations of system-reservoir interactions, namely, the three-body one, the two-body one with and without intrasystem interaction between two subsystems. After establishing general formulations of thermodynamics quantities, we derive specific forms of heat and work with respect to these three configurations based on a model with two coupled qubits. It is shown that both the amount and sign of work are closely related to ways of system-reservoir interactions, by which six types of operating regimes of machines are constructed for a given setting. We find that different modes of system-reservoir interactions lead to different numbers of operating regimes of machines on the one hand, and on the other hand machines of the same kinds can appear in different scenarios of system-reservoir interactions, but which one is superior over others relies on intervals of parameters. A possible implementation of the setup based on the platform of circuit quantum electrodynamics is discussed briefly. We then generalize the bipartite model to multipartite case and derive the corresponding formulations of thermodynamics quantities. Our results indicate that interacting manners of system-reservoir play an important role in modifying thermodynamics process and can thus be utilized in designing quantum thermal machines with requisite functions.

Obtaining the total wavefunction evolution of interacting quantum systems provides access to important properties, such as entanglement, shedding light on fundamental aspects, e.g., quantum energetics and thermodynamics, and guiding towards possible application in the fields of quantum computation and communication. We consider a two-level atom (qubit) coupled to the continuum of travelling modes of a field confined in a one-dimensional chiral waveguide. Originally, we treated the light-matter ensemble as a closed, isolated system. We solve its dynamics using a collision model where individual temporal modes of the field locally interact with the qubit in a sequential fashion. This approach allows us to obtain the total wavefunction of the qubit-field system, at any time, when the field starts in a coherent or a single-photon state. Our method is general and can be applied to other initial field states.

This paper explores the idea of applying a machine learning approach to develop a global road safety performance function (SFP) that can be used to predict the expected crash frequencies of different highways from different regions. A deep belief network (DBN) – one of the most popular deep learning models is introduced as an alternative to the traditional regression models for crash modelling. An extensive empirical study is conducted using three real world crash data sets covering six classes of highways as defined by location (urban vs. rural), number of lanes, access control, and region. The study involves a number of experiments aiming at addressing several critical questions pertaining to the relative performance of the DBN in terms of network structure, training method, data size, and generalization ability, as compared to the traditional regression models. The experimental results have shown that a DBN model could be trained with different crash datasets with prediction performance being at least comparable to that of the locally calibrated negative binomial (NB) model.

A The paper presents theoretical analysis of a two-phase medium model for describing shock-wave processes in dense gas particle mixtures, taking into account the chaotic motion and collisions of particles. Hyperbolicity regions and composite-type domains are identified in the governing system of equations. It is shown that the hyperbolicity region expands beyond the collisionless model. An approximate hyperbolized model is presented. Numerical solutions of the problem on the development of various shock-wave structure types are compared. The convergence properties in numerical simulations of non-conservative composite-type equations were established using the Harten and Gentry–Martin–Daly schemes. The conditions of the hyperbolized model applicability to different types of flows are obtained. It is shown that, in the general case, shock-wave processes in gas suspensions should preferably be analyzed within a complete model. [ABSTRACT FROM AUTHOR]

By means of the collision model, we study the non-Markovianity of an open quantum system S being coupled to M thermal reservoirs. In our model, each reservoir is modeled as a chain of ancillas whose intracollisions account for the occurrence of non-Markovian dynamics. We show that by incorporating M reservoir ancillas into the system, the non-Markovian dynamics of S can be embedded in the extended system that experiences a completely Markovian dynamics. The number M of involved reservoirs can thus be identified as the memory depth and determines the degree of the non-Markovianity. In the equilibrium case with identical temperatures for all the reservoirs, we show that though the non-Markovianity is proportional to M in the zero and relatively low temperature regimes, in the relatively high temperature regime such proportional relation holds only for the weak intracollisions of the reservoir ancillas. In the nonequilibrium situation, we examine the effect of temperature difference of reservoirs on the non-Markovianity. Focusing on a simple situation with two reservoirs, we observe that the nonzero temperature difference has a significant impact on the non-Markovianity. • The non-Markovianity with multiple reservoirs is studied via collision model. • Effects of reservoirs' number and temperatures in the non-Markovianity are studied. • More reservoirs can trigger and enhance the non-Markovianity in some cases. • The temperature difference of reservoirs greatly influences the non-Markovianity. [ABSTRACT FROM AUTHOR]

The present paper provides a collision model for Cosserat rods, able to represent a very general collision response, including frictional effects as well as multiple simultaneous collisions of a large number of rods. The proposed collision model falls into the category of constraint-based collision models. This concept is extended to a general class of objects sharing properties of rigid and deformable bodies, here undertaken for viscoelastic Cosserat rods. The collision constraints are imposed by collision impulses added to the external loads of the equations of motion of the colliding objects. No iterations between the equations of motion and the collision model are required. Both parts are executed in a staggered manner, so that the collision model is well separated from the equations of motion. Hence, existing solvers for Cosserat rods or similar objects can easily be extended, so that the range of application is significantly enlarged to the collisional regime. Extensive validations are presented using various test cases, ranging from a collision of a single rod with a wall to more realistic configurations with multiple simultaneous collisions of numerous rods. [ABSTRACT FROM AUTHOR]

Abstract An efficient method to capture an arbitrary number of fluid/structure interfaces in a level-set framework is built, following ideas introduced for contour capturing in image analysis. Using only three label maps and two distance functions we succeed in locating and evolving the bodies independently in the whole domain and get the distance between the closest bodies in order to apply a collision force whatever the number of cells is. The method is applied to rigid solid bodies in order to compare to the results available in the literature. In that case, a global penalization model uses the label maps to follow the solid bodies all together without a separate computation of each body velocity. Numerical simulations are performed in two- and three-dimensions. An application to immersed vesicles is also proposed and shows the capability and efficiency of the method to handle numerical contacts between elastic bodies at low resolution. Two-dimensional simulations of vesicles under various flow conditions are presented. [ABSTRACT FROM AUTHOR]

In this paper we consider a bipartite system composed of two subsystems each coupled to its own thermal environment. Based on a collision model, we mainly study whether the approximation (i.e., the inter-system coupling is ignored when modeling the system–environment interaction) is valid or not. We also address the problem of heat transport unitedly for both excitation-conserving system–environment interactions and non-excitation-conserving system–environment interactions. For the former interaction, as the inter-system interaction strength increases, at first this approximation gets worse as expected, but then counter-intuitively gets better even for a stronger inter-system coupling. For the latter interaction with asymmetry, this approximation gets progressively worse. In this case we realize a perfect thermal rectification, and we cannot find an apparent rectification effect for the former interaction. Finally and more importantly, our results show that whether this approximation is valid or not is closely related to the quantum correlations between the subsystems, i.e., the weaker the quantum correlations, the more justified the approximation and vice versa.

In the current study, a 3-D numerical simulation of two-phase flow has been conducted in a direct injection CI engine using the Eularian-Lagrangian approach and a new breakup model. The newly modified breakup scheme has been implemented for simulating the ultra-high pressure diesel injection. The effects of droplet breakup and collision model on the spray and in-cylinder gas characteristics have been examined using the open source code OpenFOAM. Spray penetration and cone angle are investigated as spray properties and surrounding gas motion are studied by in-cylinder gas velocity and pressure distribution for non-evaporating conditions. In addition, vapor penetration of the evaporating spray is presented to study the effects of current scheme on the evaporating condition. The continuous field is described by RANS equations and dynamics of the dispersed droplet is modeled by Lagrangian tracking scheme. Results of the proposed modified KHRT model are compared against other default methods in OpenFOAM and favorable agreement is achieved. Robustness and accuracy of different breakup schemes and collision models are also verified using the published experimental data. It is demonstrated that the proposed breakup scheme and Nordin collision model display very accurate results in the case of ultra-high pressure injection.