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A gravity-driven flow of grains through a narrow pipe in vacuum is studied by means of a one-dimensional model with two coefficients of restitution. Numerical simulations show clearly how density waves form when a strikingly simple criterion is fulfilled: that dissipation due to collisions between the grains and the walls of the pipe is greater per collision than that which stems from collisions between particles. Counterintuitively, the highest flow rate is observed when the number of grains per density wave grows large. We find strong indication that the number of grains per density wave always approaches a constant as the particle number tends to infinity, and that collapse to a single wave, which was often observed also in previous simulations, occurs because the number of grains is insufficient for multiple wave formation.
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http://dx.doi.org/10.1103/PhysRevE.81.061302 | DOI Listing |
PLoS One
September 2025
Department of Science, LLP "Research and Production Enterprise "Innovator", Astana, Kazakhstan.
This study investigates the physicochemical, microbiological, and microstructural changes in soft wheat grain during germination under varying moisture conditions: moderately dry, moist, and wet. Pre-harvest sprouting can severely compromise grain quality and usability; however, understanding germination-induced changes offers insights into potential utilization strategies. Physical parameters-including thousand-kernel weight, test weight, and falling number-showed strong correlation with germination time, decreasing by 8.
View Article and Find Full Text PDFMed Biol Eng Comput
September 2025
Key Laboratory of Mechanism Theory and Equipment Design of Ministry of Education, Tianjin University, Tianjin, 300072, China.
Surgical instrument segmentation plays an important role in robotic autonomous surgical navigation systems as it can accurately locate surgical instruments and estimate their posture, which helps surgeons understand the position and orientation of the instruments. However, there are still some problems affecting segmentation accuracy, like insufficient attention to the edges and center of surgical instruments, insufficient usage of low-level feature details, etc. To address these issues, a lightweight network for surgical instrument segmentation in gastrointestinal (GI) endoscopy (GESur_Net) is proposed.
View Article and Find Full Text PDFInt J Radiat Biol
September 2025
Department of Geography, Nara Women's University, Nara, Japan.
Purpose: The number of oxygen vacancies in quartz measured by electron spin resonance (ESR) as the intensity of the E' center has been used to investigate the provenance of the sediments and has been found to be a good proxy in discussing the direction and intensity of the wind system in the past. While its temporal variations have been examined using marine sediments. The present study aimed to show that terrestrial sediments are also useful for such studies on climate change when it is continuous.
View Article and Find Full Text PDFJ Thermoplast Compos Mater
August 2025
Institute for Applied Materials - Microstructure Modeling and Simulation, Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany.
In this paper, we introduce a coarse-grained model of polymer crystallization using a multiphase-field approach. The model combines a multiphase-field method, Nakamura's kinetic equation, and the equation of heat conduction for studying microstructural evolution of crystallization under isothermal and non-isothermal conditions. The multiphase-field method provides flexibility in adding any number of phases with different properties making the model effective in studying blends or composite materials.
View Article and Find Full Text PDFMater Horiz
September 2025
Department of Chemistry, Temple University, Philadelphia, PA 19122, USA.
This work presents the synthesis of a molecular crystal of adiponitrile (Adpn) and LiI a simple melting method. The molecular crystal has both Li and I channels and can be either a Li or an I conductor. In the stoichiometric crystal (Adpn)LiI, the Li ions interact only with four CN groups of Adpn, while the I ions are uncoordinated.
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