scholarly journals Biased diffusion in periodic potentials: Three types of force dependence of effective diffusivity and generalized Lifson-Jackson formula

2019 ◽  
Vol 151 (13) ◽  
pp. 131102
Author(s):  
Alexander M. Berezhkovskii ◽  
Leonardo Dagdug
Keyword(s):  
Effective Diffusivity ◽  
Periodic Potentials ◽  
Biased Diffusion

scholarly journals Nonequilibrium Transport and Phase Transitions in Driven Diffusion of Interacting Particles

2020 ◽  
Vol 75 (5) ◽  
pp. 449-463
Author(s):  
Dominik Lips ◽  
Artem Ryabov ◽  
Philipp Maass
Keyword(s):  
Current Density ◽  
Lattice Gas ◽  
Yukawa Potential ◽  
Exclusion Process ◽  
Quantum Spin ◽  
Nonequilibrium Steady States ◽  
Interacting Particles ◽  
Driven Diffusive Systems ◽  
Periodic Potentials ◽  
Symmetry Effect

AbstractDriven diffusive systems constitute paradigmatic models of nonequilibrium physics. Among them, a driven lattice gas known as the asymmetric simple exclusion process (ASEP) is the most prominent example for which many intriguing exact results have been obtained. After summarising key findings, including the mapping of the ASEP to quantum spin chains, we discuss the recently introduced Brownian ASEP (BASEP) as a related class of driven diffusive system with continuous space dynamics. In the BASEP, driven Brownian motion of hardcore-interacting particles through one-dimensional periodic potentials is considered. We study whether current–density relations of the BASEP can be considered as generic for arbitrary periodic potentials and whether repulsive particle interactions other than hardcore lead to similar results. Our findings suggest that shapes of current–density relations are generic for single-well periodic potentials and can always be attributed to the interplay of a barrier reduction, blocking, and exchange symmetry effect. This implies that in general up to five different phases of nonequilibrium steady states are possible for such potentials. The phases can occur in systems coupled to particle reservoirs, where the bulk density is the order parameter. For multiple-well periodic potentials, more complex current–density relations are possible, and more phases can appear. Taking a repulsive Yukawa potential as an example, we show that the effects of barrier reduction and blocking on the current are also present. The exchange symmetry effect requires hardcore interactions, and we demonstrate that it can still be identified when hardcore interactions are combined with weak Yukawa interactions. The robustness of the collective dynamics in the BASEP with respect to variations of model details can be a key feature for a successful observation of the predicted current–density relations in actual physical systems.

scholarly journals Estimation of moisture ratio for apple drying by convective and microwave methods using artificial neural network modeling

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Vali Rasooli Sharabiani ◽  
Mohammad Kaveh ◽  
Roozbeh Abdi ◽  
Mariusz Szymanek ◽  
Wojciech Tanaś
Keyword(s):  
Specific Energy Consumption ◽  
Effective Diffusivity ◽  
Moisture Ratio ◽  
Microwave Drying ◽  
Convective Drying ◽  
Neural Network Modeling ◽  
Drying Methods ◽  
Apple Slices ◽  
Artificial Neural ◽  
Drying Technology

AbstractTwo different drying methods were applied for dehydration of apple, i.e., convective drying (CD) and microwave drying (MD). The process of convective drying through divergent temperatures; 50, 60 and 70 °C at 1.0 m/s air velocity and three different levels of microwave power (90, 180, and 360 W) were studied. In the analysis of the performance of our approach on moisture ratio (MR) of apple slices, artificial neural networks (ANNs) was used to provide with a background for further discussion and evaluation. In order to evaluate the models mentioned in the literature, the Midilli et al. model was proper for dehydrating of apple slices in both MD and CD. The MD drying technology enhanced the drying rate when compared with CD drying significantly. Effective diffusivity (Deff) of moisture in CD drying (1.95 × 10−7–4.09 × 10−7 m2/s) was found to be lower than that observed in MD (2.94 × 10−7–8.21 × 10−7 m2/s). The activation energy (Ea) values of CD drying and MD drying were 122.28–125 kJ/mol and 14.01–15.03 W/g respectively. The MD had the lowest specific energy consumption (SEC) as compared to CD drying methods. According to ANN results, the best R2 values for prediction of MR in CD and MD were 0.9993 and 0.9991, respectively.

Landau–Zener tunneling in spin–orbit-coupled Bose–Einstein condensates in PT periodic potentials

Optik ◽  
2021 ◽  
Vol 231 ◽  
pp. 166350
Author(s):  
T.F. Xu ◽  
B.Y. Shen ◽  
C.Y. Zhou ◽  
Y.H. Liu
Keyword(s):  
Spin Orbit ◽  
Periodic Potentials ◽  
Zener Tunneling ◽  
Bose Einstein

scholarly journals Asymmetric Loop Spectra and Unbroken Phase Protection due to Nonlinearities in PT -Symmetric Periodic Potentials

2021 ◽  
Vol 127 (3) ◽  
Author(s):  
Yongping Zhang ◽  
Zhu Chen ◽  
Biao Wu ◽  
Thomas Busch ◽  
Vladimir V. Konotop
Keyword(s):  
Periodic Potentials

Effects of flow heterogeneity on the measurement of capillary exchange in the lung

1995 ◽  
Vol 79 (5) ◽  
pp. 1449-1460 ◽  
Author(s):  
S. D. Caruthers ◽  
T. R. Harris ◽  
K. A. Overholser ◽  
N. A. Pou ◽  
R. E. Parker
Keyword(s):  
Effective Diffusivity ◽  
Relative Dispersion ◽  
Flow Heterogeneity ◽  
Homogeneous Flow ◽  
Capillary Recruitment ◽  
Flow Models ◽  
Capillary Exchange ◽  
Variable Recruitment ◽  
Area Product ◽  
Recruitment Model

The effects of flow heterogeneity on the measurement of transcapillary escape of small molecules for perfused in situ sheep lungs were evaluated. Lungs were studied at five flows (1.5–5.0 l/min) ranging from zone 1 to zone 3 conditions. At each flow, multiple indicator-dilution curves were collected using 14C-labeled urea (U) or butanediol (B) as the diffusing tracer, and radiolabeled 15-microns microspheres were injected. The lungs were removed, dried, sectioned, weighed, and counted for microsphere radioactivity. Flow heterogeneity expressed as relative dispersion, decreased with increasing flow, from 0.838 +/- 0.179 (mean +/- SD, n = 8) to 0.447 +/- 0.119 (n = 6). We applied homogeneous flow models of capillary exchange to compute permeability-surface area product (PS) and a related parameter, D1/2S, for diffusing tracers. (D is effective diffusivity of capillary exchange.) PS and D1/2S increased to a maximum with increasing flow, but the ratio of D1/2SU to D1/2SB remained constant. A new model incorporating flow heterogeneity and recruitment (the variable recruitment model) was used. The variable recruitment model described the effects of flow on capillary recruitment, but incorporating heterogeneity into the computation did not alter D1/2S values from those computed assuming homogeneous flow.

scholarly journals Reconciling Lagrangian Diffusivity and Effective Diffusivity in Contour-Based Coordinates

2019 ◽  
Vol 49 (6) ◽  
pp. 1521-1539
Author(s):  
Yu-Kun Qian ◽  
Shiqiu Peng ◽  
Chang-Xia Liang
Keyword(s):  
Time Lag ◽  
Effective Diffusivity ◽  
Delta Function ◽  
Spreading Rate ◽  
Particle Dispersion ◽  
Small Scale ◽  
Time Lags ◽  
Conservative Tracer ◽  
Stirring Effect ◽  
Short Time

AbstractThe present study reconciles theoretical differences between the Lagrangian diffusivity and effective diffusivity in a transformed spatial coordinate based on the contours of a quasi-conservative tracer. In the transformed coordinate, any adiabatic stirring effect, such as shear-induced dispersion, is naturally isolated from diabatic cross-contour motions. Therefore, Lagrangian particle motions in the transformed coordinate obey a transformed zeroth-order stochastic (i.e., random walk) model with the diffusivity replaced by the effective diffusivity. Such a stochastic model becomes the theoretical foundation on which both diffusivities are exactly unified. In the absence of small-scale diffusion, particles do not disperse at all in the transformed contour coordinate. Besides, the corresponding Lagrangian autocorrelation becomes a delta function and is thus free from pronounced overshoot and negative lobe at short time lags that may be induced by either Rossby waves or mesoscale eddies; that is, particles decorrelate immediately and Lagrangian diffusivity is already asymptotic no matter how small the time lag is. The resulting instantaneous Lagrangian spreading rate is thus conceptually identical to the effective diffusivity that only measures the instantaneous irreversible mixing. In these regards, the present study provides a new look at particle dispersion in contour-based coordinates.

Diffusion and Migration of Ions in Sedimentary Rock Matrix: Effects of Ionic Strength and Tracer Concentration on Diffusion of Cs+ ions in Sandstone

2003 ◽  
Vol 807 ◽  
Author(s):  
Haruo Sato
Keyword(s):  
Ionic Strength ◽  
Matrix Effects ◽  
Chemical Properties ◽  
Effective Diffusivity ◽  
Concentration Profiles ◽  
Tracer Concentration ◽  
And Migration ◽  
Physical And Chemical ◽  
Cs Ions ◽  
And Chemical Properties

ABSTRACTIn-diffusion experiments for Cs+ and I− in sandstone were performed as a function of ionic strength ([NaCl]=0.01, 0.51M) and tracer concentration ([CsI]=7.5E-5, 1.5E-2M) together with the measurements of the physical and chemical properties of sandstone, and apparent diffusivities (Da) for Cs+ were obtained. The obtained Da-values for Cs+ scarcely depended on [NaCl], but increased with increasing [Cs+]. This trend is consistent with that of rock capacity factors (α), indicating that distribution coefficient (Kd) onto sandstone and effective diffusivity scarcely depend on [NaCl]. The concentration profiles of I− were all in already breakthrough. Although this indicates that I− diffusion is faster than that of Cs+, the concentration profiles of I− may have been lower than those for blank samples, judging synthetically from the correlations between α-values and the concentration profiles of Cs+ and from the concentration profiles of I− in the blank samples. Finally, the effects of [Cs+] and[NaCl] on Kd/-values for Cs+ were discussed from the viewpoint of adsorption by ion exchange and electrostatic attraction. The kd-values were considered to be combined sorption by both reactions.

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