We investigate, for the first time, navigation on networks with a Lévy walk strategy such that the step probability scales as pij ~ dij(-α), where dij is the Manhattan distance between nodes i and j, and α is the transport exponent. We find that the optimal transport exponent α(opt) of such a diffusion process is determined by the fractal dimension df of the underlying network. Specially, we theoretically derive the relation α(opt) = df + 2 for synthetic networks and we demonstrate that this holds for a number of real-world networks. Interestingly, the relationship we derive is different from previous results for Kleinberg navigation without or with a cost constraint, where the optimal conditions are α = df and α = df + 1, respectively. Our results uncover another general mechanism for how network dimension can precisely govern the efficient diffusion behavior on diverse networks.
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http://dx.doi.org/10.1038/srep17309 | DOI Listing |
PNAS Nexus
January 2025
Faculty of Architecture, and Urban Systems Institute, The University of Hong Kong, Pok Fu Lam, Hong Kong SAR.
Surfacic networks are structures built upon a 2D manifold. Many systems, including transportation networks and various urban networks, fall into this category. The fluctuations of node elevations imply significant deviations from typical plane networks and require specific tools to understand their impact.
View Article and Find Full Text PDFChaos
January 2025
Instituto de Física, Universidad Nacional Autónoma de México, Mexico City 04510, Mexico.
We study an exactly solvable random walk model with long-range memory on arbitrary networks. The walker performs unbiased random steps to nearest-neighbor nodes and intermittently resets to previously visited nodes in a preferential way such that the most visited nodes have proportionally a higher probability to be chosen for revisit. The occupation probability can be expressed as a sum over the eigenmodes of the standard random walk matrix of the network, where the amplitudes slowly decay as power-laws at large times, instead of exponentially.
View Article and Find Full Text PDFPLoS One
December 2024
Department of Geography, National Taiwan Normal University, Taipei, Taiwan.
The impact of flood diversion channels on river sediment transport has been rarely reported. This study uses the Yuanshantze flood diversion tunnel (YFDT), which was commissioned in July 2005 in Taiwan, as an example. This study calculates the sediment transport in the Keelung River from 1997 to 2018 by using seasonal rating curves, in the form of aQb.
View Article and Find Full Text PDFSmall
December 2024
Institute Charles Sadron, UPR022 CNRS - University of Strasbourg, 23 rue du loess, Strasbourg, 67034, France.
In this contribution, doping of oriented thin films is investigated for three PBTTT polymers bearing different side chains including linear alkyl ─(CH)─H, single ether ─(CH)─O─(CH)─H and alkyl-siloxane ─(CH)─(Si(CH)O)─Si(CH) A combination of transmission electron microscopy, polarized UV-vis-NIR spectroscopy and transport measurements helps uncover the essential role of the chemical nature of side chains on the efficacy of the doping and on the resulting thermoelectric performances in oriented PBTTT films. Siloxane side chains help to reach record alignment level of PBTTT with dichroic ratio beyond 50 for an optimized rubbing temperature but they impede effective doping of PBTTT crystals with FTCNNQ, resulting in very poor TE properties. By contrast, doping the amorphous phase of all three PBTTTs with magic blue (MB) results in excellent TE performances.
View Article and Find Full Text PDFNanoscale
December 2024
Layered Materials and Device Physics Laboratory, Department of Chemistry, Physics and Atmospheric Science, Jackson State University, Jackson, MS 39217, USA.
The metal-to-insulator phase transition (MIT) in two-dimensional (2D) materials under the influence of a gating electric field has revealed interesting electronic behavior and the need for a deeper fundamental understanding of electron transport processes, while attracting much interest in the development of next-generation electronic and optoelectronic devices. Although the mechanism of the MIT in 2D semiconductors is a topic under debate in condensed matter physics, our work demonstrates the tunable percolative phase transition in few-layered MoSe field-effect transistors (FETs) using different metallic contact materials. Here, we attempted to understand the MIT through temperature-dependent electronic transport measurements by tuning the carrier density in a MoSe channel under the influence of an applied gate voltage.
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