Velocity and diffusion coefficient of a random asymmetric one-dimensional hopping model

1989 ◽  
Vol 50 (8) ◽  
pp. 899-921 ◽  
Author(s):  
C. Aslangul ◽  
N. Pottier ◽  
D. Saint-James
Keyword(s):  
Diffusion Coefficient ◽  
One Dimensional ◽  
And Diffusion ◽  
Hopping Model

Potential of Silver Nanoparticles Functionalized Polyaniline as an Electrochemical Transducer

2016 ◽  
Vol 44 ◽  
pp. 21-34 ◽  
Author(s):  
Malefetsane Khesuoe ◽  
Mangaka Matoetoe ◽  
Fredrick Okumu
Keyword(s):  
Silver Nanoparticles ◽  
Diffusion Coefficient ◽  
Surface Coverage ◽  
Current Response ◽  
Ag Nps ◽  
One Dimensional ◽  
Transmission Electron ◽  
Doped Polyaniline ◽  
And Diffusion ◽  
Electrochemical Transducer

Modification of commercial platinum (Pt) and glassy carbon (GC) electrodes with polyaniline (PANI) and silver nanoparticles doped polyaniline (PANI/Ag NPs) through electropolymerization of aniline in the absence and presence of Ag NPs in 1 M hydrochloric acid (HCl) was interrogated. Fourier transform infrared (FTIR) and transmission electron microscope (TEM) techniques were used for structural, compositional and morphological elucidation. FTIR spectra for PANI and PANI/Ag NPs had the characteristic PANI functional groups as well as desired bands for the conducting emeraldine (EM) form. The predominance of the PANI pattern in the spectra is indicative of the intact PANI structure in the presence of Ag NPs while the slight band shifts are signify interfacial interactions between PANI and Ag NPs. TEM micrograms depicts different size one dimensional nanofibric tubes of the supramolecular structures of PANI. Ag NPs functionalized PANI had larger smoother tubes, suggesting organized morphology arrangement. An increased energy dispersive spectroscopy (EDS)-TEM count from 256 to 277 confirms incorporation of Ag NPs in PANI. GC/PANI/Ag NPs exhibited outstanding electroactivity (higher conductivity and rate of electron transfer).This might be a result of the large surface coverage, film thickness and diffusion coefficient as a result of the large GC surface area. Possibly, the improvement might be due to the GC electrode properties. The electroactivity of the electrodes increased in the order: Pt < GC < Pt/PANI < Pt/PANI/Ag NPs < GC/PANI < GC/PANI/Ag NPs. The effect of Ag NPs in the polymer was demonstrated by ultimate band gap reduction of PANI and enhanced magnitudes of current response per electrode.

PERMEABILITY AND DIFFUSION COEFFICIENT PREDICTION OF FRACTAL POROUS MEDIA WITH NANOSCALE PORES FOR GAS TRANSPORT

2018 ◽  
Vol 21 (12) ◽  
pp. 1253-1263
Author(s):  
Ruifei Wang ◽  
Hongqing Song ◽  
Jiulong Wang ◽  
Yuhe Wang
Keyword(s):  
Porous Media ◽  
Diffusion Coefficient ◽  
Gas Transport ◽  
And Diffusion

scholarly journals Ergodic control of diffusions with random intervention times

2021 ◽  
Vol 58 (1) ◽  
pp. 1-21
Author(s):  
Harto Saarinen ◽  
Jukka Lempa
Keyword(s):  
Optimal Solution ◽  
Singular Control ◽  
Control Policy ◽  
Control Problems ◽  
Ergodic Control ◽  
Linear Diffusion ◽  
One Dimensional ◽  
And Diffusion ◽  
Independent Poisson Process ◽  
Exact Amount

AbstractWe study an ergodic singular control problem with constraint of a regular one-dimensional linear diffusion. The constraint allows the agent to control the diffusion only at the jump times of an independent Poisson process. Under relatively weak assumptions, we characterize the optimal solution as an impulse-type control policy, where it is optimal to exert the exact amount of control needed to push the process to a unique threshold. Moreover, we discuss the connection of the present problem to ergodic singular control problems, and illustrate the results with different well-known cost and diffusion structures.

scholarly journals Anomalous Diffusion with an Apparently Negative Diffusion Coefficient in a One-Dimensional Quantum Molecular Chain Model

Symmetry ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 506
Author(s):  
Sho Nakade ◽  
Kazuki Kanki ◽  
Satoshi Tanaka ◽  
Tomio Petrosky
Keyword(s):  
Diffusion Coefficient ◽  
Diffusion Constant ◽  
Mean Square Displacement ◽  
Second Law Of Thermodynamics ◽  
Molecular Chain ◽  
Chain Model ◽  
Phase Mixing ◽  
One Dimensional ◽  
The One ◽  
Negative Diffusion

An interesting anomaly in the diffusion process with an apparently negative diffusion coefficient defined through the mean-square displacement in a one-dimensional quantum molecular chain model is shown. Nevertheless, the system satisfies the H-theorem so that the second law of thermodynamics is satisfied. The reason why the “diffusion constant” becomes negative is due to the effect of the phase mixing process, which is a characteristic result of the one-dimensionality of the system. We illustrate the situation where this negative “diffusion constant” appears.

scholarly journals LATTICE THREE-SPECIES MODELS OF THE SPATIAL SPREAD OF RABIES AMONG FOXES

1999 ◽  
Vol 10 (06) ◽  
pp. 1025-1038 ◽  
Author(s):  
A. BENYOUSSEF ◽  
N. BOCCARA ◽  
H. CHAKIB ◽  
H. EZ-ZAHRAOUY
Keyword(s):  
Carrying Capacity ◽  
Short Range ◽  
Lattice Models ◽  
Infection Process ◽  
Spatial Spread ◽  
One Dimensional ◽  
Sense Of Direction ◽  
Speed Of Propagation ◽  
Automata Network ◽  
And Diffusion

Lattice models describing the spatial spread of rabies among foxes are studied. In these models, the fox population is divided into three-species: susceptible (S), infected or incubating (I), and infectious or rabid (R). They are based on the fact that susceptible and incubating foxes are territorial while rabid foxes have lost their sense of direction and move erratically. Two different models are investigated: a one-dimensional coupled-map lattice model, and a two-dimensional automata network model. Both models take into account the short-range character of the infection process and the diffusive motion of rabid foxes. Numerical simulations show how the spatial distribution of rabies, and the speed of propagation of the epizootic front depend upon the carrying capacity of the environment and diffusion of rabid foxes out of their territory.

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