scholarly journals Fractal Generalization of the Scher–Montroll Model for Anomalous Transit-Time Dispersion in Disordered Solids

Mathematics ◽  
2020 ◽  
Vol 8 (11) ◽  
pp. 1991
Author(s):  
Renat T. Sibatov
Keyword(s):  
Transit Time ◽  
Time Of Flight ◽  
Fractal Model ◽  
Localized States ◽  
Spatial Correlations ◽  
Dispersive Transport ◽  
Disordered Solids ◽  
Time Dispersion ◽  
Longitudinal Coordinate

The Scher–Montroll model successfully describes subdiffusive photocurrents in homogeneously disordered semiconductors. The present paper generalizes this model to the case of fractal spatial disorder (self-similar random distribution of localized states) under the conditions of the time-of-flight experiment. Within the fractal model, we calculate charge carrier densities and transient current for different cases, solving the corresponding fractional-order equations of dispersive transport. Photocurrent response after injection of non-equilibrium carriers by the short laser pulse is expressed via fractional stable distributions. For the simplest case of one-sided instantaneous jumps (tunneling) between neighboring localized states, the dispersive transport equation contains fractional Riemann–Liouville derivatives on time and longitudinal coordinate. We discuss the role of back-scattering, spatial correlations induced by quenching of disorder, and spatiotemporal non-locality produced by the fractal trap distribution and the finite velocity of motion between localized states. We derive expressions for the photocurrent and transit time that allow us to determine the fractal dimension of the distribution of traps and the dispersion parameter from the time-of-flight measurements.

scholarly journals Transport timescales and tracer properties in the extratropical UTLS

2010 ◽  
Vol 10 (5) ◽  
pp. 12953-12991 ◽  
Author(s):  
P. Hoor ◽  
H. Wernli ◽  
M. I. Hegglin
Keyword(s):  
Transit Time ◽  
Chemical Structure ◽  
Comprehensive Evaluation ◽  
Mixing Ratio ◽  
Backward Trajectories ◽  
Tropical Tropopause ◽  
Northern Winter ◽  
Cold Point ◽  
The Tropics

Abstract. A comprehensive evaluation of seasonal backward trajectories initialized in the Northern Hemisphere lowermost stratosphere (LMS) has been performed to investigate the origin of air parcels and the main mechanisms determining characteristic structures in H2O and CO within the LMS. In particular we explain the fundamental role of the transit time since last tropopause crossing (tTST) for the chemical structure of the LMS as well as the feature of the extra-tropical tropopause transition layer (ExTL) as identified from CO profiles. The distribution of H2O in the background LMS above Θ=320 K and 340 K in northern winter and summer, respectively, is found to be governed mainly by the saturation mixing ratio, which in turn is determined by the Lagrangian Cold Point (LCP) encountered by each trajectory. Most of the backward trajectories from this region in the LMS experienced their LCP in the tropics and sub-tropics. The transit time since crossing the tropopause from the troposphere to the stratosphere (tTST) is independent of the H2O value of the air parcel. TST often occurs 20 days after trajectories have encountered their LCP. CO, on the other hand, depends strongly on tTST due to its finite lifetime. The ExTL as identified from CO measurements is then explained as a layer of air just above the tropopause, which on average encountered TST fairly recently.

scholarly journals Role of packing density and spatial correlations in strongly scattering 3D systems

Optica ◽  
2018 ◽  
Vol 5 (9) ◽  
pp. 1037 ◽  
Author(s):  
Lorenzo Pattelli ◽  
Amos Egel ◽  
Uli Lemmer ◽  
Diederik S. Wiersma
Keyword(s):  
Packing Density ◽  
Spatial Correlations

Manifestation of Carrier Relaxation Through the Manifold of Localized States in PCDTBT:PC60BM Bulk Heterojunction Material: The Role of PC84BM Traps on the Carrier Transport

2012 ◽  
Vol 24 (17) ◽  
pp. 2273-2277 ◽  
Author(s):  
Wei Lin Leong ◽  
Gerardo Hernandez-Sosa ◽  
Sarah R. Cowan ◽  
Daniel Moses ◽  
Alan J. Heeger
Keyword(s):  
Carrier Transport ◽  
Bulk Heterojunction ◽  
Localized States ◽  
Carrier Relaxation

Role of electron heating in efficient interaction of a nanosecond laser with the cluster media: a case study on tetrahydrofuran cluster system

RSC Advances ◽  
2016 ◽  
Vol 6 (91) ◽  
pp. 87897-87904 ◽  
Author(s):  
Pramod Sharma ◽  
Soumitra Das ◽  
Rajesh K. Vatsa
Keyword(s):  
Mass Spectrometer ◽  
Time Of Flight ◽  
Laser Pulses ◽  
Nanosecond Laser ◽  
Electron Heating ◽  
Flight Mass Spectrometer ◽  
System P ◽  
Nanosecond Laser Pulses

Interaction of tetrahydrofuran clusters with nanosecond laser pulses has been investigated at 532 and 1064 nm, using a time-of-flight mass spectrometer and home-built electron analyzer setup.

Spatial Correlations in CyberShake Physics‐Based Ground‐Motion Simulations

2019 ◽  
Vol 109 (6) ◽  
pp. 2447-2458 ◽  
Author(s):  
Yilin Chen ◽  
Jack W. Baker
Keyword(s):  
Ground Motion ◽  
Prediction Models ◽  
Spatial Correlations ◽  
Ground Motion Simulation ◽  
Source Effects ◽  
Simulation Validation ◽  
Geological Conditions ◽  
Simulated Ground Motions ◽  
Strong Ground

Abstract When studying the performance of distributed infrastructure in earthquakes, spatial variations in strong ground motion have a significant impact. Currently, prediction models for spatial ground‐motion variations in future earthquakes are calibrated using ground‐motion observations from densely recorded earthquakes. Although useful, that calibration process requires strong assumptions about stationarity and isotropy of correlations. This article reports results from conducting analogous spatial variation estimation using physics‐based simulations from the CyberShake platform. This platform contains simulated ground motions from hundreds of thousands of rupture realizations, at locations throughout southern California, providing a synthetic ground‐motion catalog that is much richer than we could ever hope to achieve from recordings. That richness allows significant relaxation of stationarity and isotropy assumptions, and provides new insights regarding the role of source and path heterogeneity on the spatial correlation of ground‐motion amplitudes. The results suggest that geological conditions, source effects, and path effects have significant impacts on spatial correlations. In addition, this work serves as a new dimension of ground‐motion simulation validation, because the estimated correlations can be compared to results from past earthquakes.

Transit time dispersion in the pulmonary arterial tree

1998 ◽  
Vol 85 (2) ◽  
pp. 565-574 ◽  
Author(s):  
Anne V. Clough ◽  
Steven T. Haworth ◽  
Christopher C. Hanger ◽  
Jerri Wang ◽  
David L. Roerig ◽  
...  
Keyword(s):  
Transit Time ◽  
Mean Transit Time ◽  
Arterial Tree ◽  
Lung Lobe ◽  
Transit Times ◽  
Pulmonary Capillary ◽  
Time Dispersion ◽  
Pulmonary Arterial ◽  
The Difference ◽  
In Transit

Knowledge of the contributions of arterial and venous transit time dispersion to the pulmonary vascular transit time distribution is important for understanding lung function and for interpreting various kinds of data containing information about pulmonary function. Thus, to determine the dispersion of blood transit times occurring within the pulmonary arterial and venous trees, images of a bolus of contrast medium passing through the vasculature of pump-perfused dog lung lobes were acquired by using an X-ray microfocal angiography system. Time-absorbance curves from the lobar artery and vein and from selected locations within the intrapulmonary arterial tree were measured from the images. Overall dispersion within the lung lobe was determined from the difference in the first and second moments (mean transit time and variance, respectively) of the inlet arterial and outlet venous time-absorbance curves. Moments at selected locations within the arterial tree were also calculated and compared with those of the lobar artery curve. Transit times for the arterial pathways upstream from the smallest measured arteries (200-μm diameter) were less than ∼20% of the total lung lobe mean transit time. Transit time variance among these arterial pathways (interpathway dispersion) was less than ∼5% of the total variance imparted on the bolus as it passed through the lung lobe. On average, the dispersion that occurred along a given pathway (intrapathway dispersion) was negligible. Similar results were obtained for the venous tree. Taken together, the results suggest that most of the variation in transit time in the intrapulmonary vasculature occurs within the pulmonary capillary bed rather than in conducting arteries or veins.

Sign in / Sign up

Export Citation Format

Share Document