Physical Review E最新文献

{"title":"Model and simulations of the effects of polyelectrolyte-coated electrodes in capacitive deionization.","authors":"J A Lirio Piñar, J Calvo, S Ahualli","doi":"10.1103/PhysRevE.110.034610","DOIUrl":"https://doi.org/10.1103/PhysRevE.110.034610","url":null,"abstract":"<p><p>The problem of ion transport in porous media is fundamental to many practical applications such as capacitive deionization, where ions are electrostatically attracted to a porous electrode and stored in the electric double layer, leaving a partially desalinated solution. These electrodes are functionalized to achieve maximum efficiency: it is intended that for each depleted electron one ion is removed. For this purpose, the surface is coated with a polyelectrolyte layer of the same sign as the electronic charge. In this work, the movement of ions from the solution to the soft or polyelectrolyte-coated electrodes is studied. For this purpose, a one-dimensional model is used to study the electric and diffusive fluxes produced by the application of an electric field and the storage of these ions in the micropores. The partial differential equations governing the process are numerically solved using the explicit Euler method. The results of the model indicate that the number of ions removed using soft electrodes is approximately 15% greater than that achieved with bare electrodes. Ion adsorption kinetics show that coated electrodes provide slightly slower adsorption compared to bare electrodes. Regarding the charging time of the micropores, it can be seen that it is a faster process (characteristic time of 100 s) compared to the time in which the ion concentration reaches equilibrium: electromigration is faster than diffusion. Comparing the situations with and without polyelectrolyte coating, it is observed that saturation in the micropores is reached earlier when the electrodes are coated. Concerning the cell geometry, it has been found that the characteristic time is proportional to the length of the spacer and inversely proportional to the length of the electrodes. With regard to microporosity, the rate of the process is approximately constant, irrespective of the number of micropores. Moreover, the number of adsorbed ions strongly depends on their initial concentration. Finally, the analysis of the ionic diffusion coefficient is determinant in the kinetics of the process: Taking into account the tortuosity of the porous electrode, which directly affects the diffusion in the channel, is fundamental to obtain model predictions close to reality.</p>","PeriodicalId":48698,"journal":{"name":"Physical Review E","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142478230","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Quantum entanglement in a mixed-spin trimer: Effects of a magnetic field and heterogeneous g factors.","authors":"Zhirayr Adamyan, Vadim Ohanyan","doi":"10.1103/PhysRevE.110.034131","DOIUrl":"https://doi.org/10.1103/PhysRevE.110.034131","url":null,"abstract":"<p><p>Mixed spin-(1/2,1/2,1) trimer with two different Landé g factors and two different exchange couplings is considered. The main feature of the model is nonconserving magnetization. The Hamiltonian of the system is diagonalized analytically. We presented a detailed analysis of the ground-state properties, revealing several possible ground-state phase diagrams and magnetization profiles. The main focus is on how nonconserving magnetization affects quantum entanglement. We have found that nonconserving magnetization can bring a continuous dependence of the entanglement quantifying parameter (negativity) on the magnetic field within the same eigenstate, while for the case of uniform g factors it is a constant. The main result is an essential enhancement of the entanglement in the case of uniform couplings for one pair of spins caused by an arbitrary small difference in the values of g factors. This enhancement is robust and brings almost a sevenfold increase of the negativity. We have also found a weakening of entanglement for other cases. Thus, nonconserving magnetization offers a broad opportunity to manipulate the entanglement by means of a magnetic field.</p>","PeriodicalId":48698,"journal":{"name":"Physical Review E","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142478241","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Critical dimension for hydrodynamic turbulence.","authors":"Mahendra K Verma","doi":"10.1103/PhysRevE.110.035102","DOIUrl":"https://doi.org/10.1103/PhysRevE.110.035102","url":null,"abstract":"<p><p>Hydrodynamic turbulence exhibits nonequilibrium behavior with k^{-5/3} energy spectrum, and equilibrium behavior with k^{d-1} energy spectrum and zero viscosity, where d is the space dimension. Using recursive renormalization group in Craya-Herring basis, we show that the nonequilibrium solution is valid only for d<6, whereas equilibrium solution with zero viscosity is the only solution for d>6. Thus, d=6 is the critical dimension for hydrodynamic turbulence. In addition, we show that the energy flux changes sign from positive to negative near d=2.15. We also compute the energy flux and Kolmogorov's constants for various d's, and observe that our results are in good agreement with past numerical results.</p>","PeriodicalId":48698,"journal":{"name":"Physical Review E","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142478251","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"General theory for discrete symmetry-breaking equilibrium states in quantum systems.","authors":"Ángel L Corps, Armando Relaño","doi":"10.1103/PhysRevE.110.034137","DOIUrl":"https://doi.org/10.1103/PhysRevE.110.034137","url":null,"abstract":"<p><p>Spontaneous symmetry breaking in phase transitions occurs when the system Hamiltonian is symmetric under a certain transformation, but the equilibrium states observed in nature are not. Here we build two noncommuting quantities from the order parameter of the transition and the symmetry operator that are constants of motion when such equilibrium states exist. Then, we derive a general equilibrium ensemble for the ordered phase and show that equilibrium states consisting of superpositions of different symmetry-breaking states, like positive and negative magnetized states, may exist. We propose an experimental realization of such equilibrium states with the state-of-the-art quantum technologies, and test it by means of numerical calculations. Finally, we show that a small symmetry-breaking perturbation in the Hamiltonian stabilizes the conservation of one of the two former quantities, implying that symmetry-breaking equilibrium states become stable even in small quantum systems.</p>","PeriodicalId":48698,"journal":{"name":"Physical Review E","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142478224","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Fully polarized Fermi systems at finite temperature.","authors":"Krzysztof Myśliwy, Marek Napiórkowski","doi":"10.1103/PhysRevE.110.034129","DOIUrl":"https://doi.org/10.1103/PhysRevE.110.034129","url":null,"abstract":"<p><p>We propose a simple model of an interacting, fully spin-polarized Fermi gas in dimensions d=2 and d=3, and derive the approximate expression for the energy spectrum and the corresponding formula for the Helmholtz free energy. We analyze the thermodynamics of the system and find the lines of first-order phase transitions between the low- and high-density phases terminating at critical points. The properties of the corresponding phase diagrams are qualitatively different for d=2 and 3, and sensitively depend on the interparticle attraction, which marks a departure from the standard van der Waals theory. The differences originate from the Pauli exclusion principle and are embedded in the fermionic nature of the system under study.</p>","PeriodicalId":48698,"journal":{"name":"Physical Review E","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142478221","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Mutual information sums and relations with interaction energies in N-particle quantum systems.","authors":"Saúl J C Salazar, Humberto G Laguna, Robin P Sagar","doi":"10.1103/PhysRevE.110.034133","DOIUrl":"https://doi.org/10.1103/PhysRevE.110.034133","url":null,"abstract":"<p><p>The sums of position- and momentum-space mutual information measures are used to examine the pairwise and higher-order statistical correlation in the ground states of N-particle coupled oscillators. Analytical expressions for these measures are shown to be related to the logarithmic interaction energies of these states, plus those of mirror states where the intensities of the one- and two-body potentials are interchanged, and the nature of the attractive or repulsive interaction is opposite to that in the original state. The measures separate the contributions from the interactions and those from the effective interactions due to marginalization into different terms. The pairwise mutual information sum is linearly related to the Shannon entropy sum in two particle systems, while the total correlation sum exhibits a similar relationship in three particle ones. In the latter instance, the interaction information sum can be related to entropy differences. This illustrates how entropy sums are connected to correlation measure sums in these systems. All measures approach zero with large N, when the magnitudes of the one- and two-body potentials are fixed. The pair mutual information and total correlation sums decay monotonically with N in the presence of an attractive potential and monotonically increase with a repulsive potential. On the other hand, the interaction information sum exhibits a minimum at small N, with an attractive potential. This is a consequence of the higher-order correlations governing behavior at smaller N while the pairwise ones dominate at larger N. Results are presented when the magnitude of the one-body potential is set to N.</p>","PeriodicalId":48698,"journal":{"name":"Physical Review E","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142478232","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Direct microstability optimization of stellarator devices.","authors":"R Jorge, W Dorland, P Kim, M Landreman, N R Mandell, G Merlo, T Qian","doi":"10.1103/PhysRevE.110.035201","DOIUrl":"https://doi.org/10.1103/PhysRevE.110.035201","url":null,"abstract":"<p><p>Turbulent transport is regarded as one of the key issues in magnetic confinement nuclear fusion, both for tokamaks and stellarators. In this work, we show that a significant decrease in a microstability-based proxy, as opposed to a geometric one, for the turbulent heat flux, namely the quasilinear heat flux, can be obtained in an efficient manner by coupling stellarator optimization with linear gyrokinetic simulations. This is accomplished by computing the quasilinear heat flux at each step of the optimization process, as well as the deviation from quasisymmetry, and minimizing their sum, leading to a balance between neoclassical and the turbulent transport proxy.</p>","PeriodicalId":48698,"journal":{"name":"Physical Review E","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142478252","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Percolation without trapping: How Ostwald ripening during two-phase displacement in porous media alters capillary pressure and relative permeability.","authors":"Ademola Isaac Adebimpe, Sajjad Foroughi, Branko Bijeljic, Martin J Blunt","doi":"10.1103/PhysRevE.110.035105","DOIUrl":"https://doi.org/10.1103/PhysRevE.110.035105","url":null,"abstract":"<p><p>Conventional measurements of two-phase flow in porous media often use completely immiscible fluids, or are performed over time scales of days to weeks. If applied to the study of gas storage and recovery, these measurements do not properly account for Ostwald ripening, significantly overestimating the amount of trapping and hysteresis. When there is transport of dissolved species in the aqueous phase, local capillary equilibrium is achieved: this may take weeks to months on the centimeter-sized samples on which measurements are performed. However, in most subsurface applications where the two phases reside for many years, equilibrium can be achieved. We demonstrate that in this case, two-phase displacement in porous media needs to be modeled as percolation without trapping. A pore network model is used to quantify how to convert measurements of trapped saturation, capillary pressure and relative permeability made ignoring Ostwald ripening to account for this effect. We show that conventional measurements overestimate the amount of capillary trapping by 20-25%.</p>","PeriodicalId":48698,"journal":{"name":"Physical Review E","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142478258","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Micropinch formation dynamics in X pinches.","authors":"A T Elshafiey, N G Chalmers, D A Hammer","doi":"10.1103/PhysRevE.110.L033202","DOIUrl":"https://doi.org/10.1103/PhysRevE.110.L033202","url":null,"abstract":"<p><p>High temporal resolution x-ray streak camera studies of micropinch formation in Cu hybrid x pinches reveal key plasma conditions. Analysis of Ne-like Cu lines indicate an average electron temperature of about 200 eV and 4.5×10^{28}m^{-3} electron density. The spectra suggest that the electron temperature jumps to about 1 keV, inferred from the continuum and the postcontinuum line emission that includes Li-like Cu lines. There is no sign of a rapid temperature change or a substantial surge in radiation emission during the 200 ps precontinuum x-ray burst, suggesting that the radiative collapse process does not play a major role in micropinch formation. Two-dimensional extended Magnetohydrodynamic (MHD) simulations, coupled to a collisional-radiative spectral analysis code, suggest the significance of the rapid radial implosion of high-temperature, low-density plasma, the axial outflow, and the dynamic plasma pressure in micropinch formation.</p>","PeriodicalId":48698,"journal":{"name":"Physical Review E","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142478130","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"From hydrodynamics to dipolar colloids: Modeling complex interactions and self-organization with generalized potentials.","authors":"T J J M van Overveld, W G Ellenbroek, J M Meijer, H J H Clercx, M Duran-Matute","doi":"10.1103/PhysRevE.110.035103","DOIUrl":"https://doi.org/10.1103/PhysRevE.110.035103","url":null,"abstract":"<p><p>The self-organization of clusters of particles is a fundamental phenomenon across various physical systems, including hydrodynamic and colloidal systems. One example is that of dense spherical particles submerged in a viscous fluid and subjected to horizontal oscillations. The interaction of the particles with the oscillating flow leads to the formation of one-particle-thick chains or multiple-particle-wide bands, both oriented perpendicular to the oscillation direction. In this study, we model the hydrodynamic interactions between such particles and parallel chains using simplified potentials. We first focus on the hydrodynamic interactions between chains, which we characterize using data from fully resolved numerical simulations. Based on these interactions, we propose a simplified model potential, called the Siren potential, which combines the representative hydrodynamic interactions: short-range attraction, mid-range repulsion, and long-range attraction. Through one-dimensional Monte Carlo simulations, we successfully replicate the characteristic patterns observed in hydrodynamic experiments and draw the phase diagram for the model potential. We further extend our analysis to two-dimensional systems, introducing a dipole-capillary model potential that accounts for both chain formation and Siren-like chain interactions. This potential is based on a system with colloidal particles at an interface, where chain formation is driven by an external electric field that induces a dipole moment parallel to the interface in each particle. The capillary force contributes the long-range attraction. Starting with parallel chains, the patterns in the two-dimensional Monte Carlo simulations of this colloidal system are similar to those observed in the hydrodynamic experiments. However, we identify that nonlinear interactions are important for some distinct steps in the chain formation. Still, the model potentials help clarify the dynamic behavior of the particles and chains due to the complex interactions encountered in both hydrodynamic and colloidal systems, drawing parallels between them.</p>","PeriodicalId":48698,"journal":{"name":"Physical Review E","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142478254","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}