Article
Engineering, Chemical
Terunori Irie, Ryusei Yamaguchi, Sei-ichiro Watanabe, Hiroaki Katsuragi
Summary: The history dependence of rotation-induced granular deformation was experimentally examined. By capturing the deformation of a quasi-two-dimensional granular pile during rotation and analyzing the acquired image data, the relationship between the granular friction coefficient and the ratio of centrifugal force to gravity was determined. The variation of the coefficient in different rotation-rate regimes was systematically evaluated, and a force balance model was proposed to explain the observed history-dependent behaviors.
ADVANCED POWDER TECHNOLOGY
(2022)
Article
Engineering, Chemical
Mingrui Dong, Zhongzheng Wang, Yixiang Gan
Summary: This study adopts the discrete element method (DEM) to propose a strategy for tailoring packing structures by controlling the cohesive forces between particles. By comparing the results with previous experiments, the effectiveness of this strategy is demonstrated, and it is found that larger clusters tend to form looser packing structures. The study also reveals that the effect of cohesion varies throughout different stages of packing, which sheds light on the understanding of wet granular packing.
Article
Engineering, Mechanical
Xuejie Zhang, Wei Sun, Wei Wang, Kun Liu
Summary: Granular friction behaviors were investigated during a linear reciprocating sliding process using a customized experimental apparatus. The evolution of two normal forces on the shearing unit qualitatively reflected the effects of the force chain network. The coefficient of friction reached a stable value rapidly within the initial sliding stage and remained constant, showing a significant decrease with external load and a slight increase with sliding velocity.
Article
Mechanics
Mingrui Dong, Zhongzheng Wang, Benjy Marks, Yu Chen, Yixiang Gan
Summary: This study investigates partially saturated granular flows in rotating drums through experiments and simulations. It explores the effects of cohesion and rotation rate on the flow patterns and flow depth. Additionally, the study reveals that stronger cohesion promotes the formation of larger clusters.
Article
Engineering, Chemical
Artur Wojcik, Jaroslaw Fraczek
Summary: The article discusses the challenges in measuring the static friction force of granular materials from plants, highlighting the lack of clearly defined procedures that make it difficult to compare results across different researchers. The authors conducted tests using a linear tribometer and observed the influence of sample slip velocity on the maximum measured friction force, as well as the effect of inertia force on friction force oscillations during the initial phase of sample slip. They propose that the difference between the maximum and minimum forces recorded in the first friction ripple cycle can serve as a basic parameter for evaluating the impact of inertia on measurement results. To eliminate the inertia force, the authors suggest conducting tests under quasi-static conditions at a slip velocity of 0.5 mm/min.
Article
Engineering, Mechanical
Stanislaw Pabiszczak, Michal Kowal
Summary: The efficiency of a novel eccentric rolling transmission was investigated in this article, and an efficiency model was developed to predict the transmission's efficiency. The study found that the main power losses occurred in the bearings, rather than losses associated with friction between the main components.
MECHANISM AND MACHINE THEORY
(2022)
Article
Multidisciplinary Sciences
T. T. T. Nguyen, T. Doanh, A. Le Bot, D. Dalmas
Summary: In this study, the failure and distinctive sound characteristics of granular materials in isotropic compression are explained using time-frequency analysis. Additionally, the traditional seismic statistical model is extended to further understand the mechanisms of stick-slip frictional instability.
SCIENTIFIC REPORTS
(2022)
Article
Chemistry, Physical
Mohd Ilyas Bhat, Prerna Sharma, T. G. Sitharam, Tejas G. Murthy
Summary: This study investigates the mechanics of standing columns formed during the repose of flexible granular chains. By simulating experiments and evaluating various parameters, it is found that the links connecting the particles provide lateral stability to the column, enabling it to stand. In addition, a self-confining radial stress near the base of the column generated by the rearrangement of contact forces also plays an important role.
Article
Nanoscience & Nanotechnology
B. N. J. Persson, J. Biele
Summary: In this study, we investigate the heat transfer in weakly interacting particle systems in vacuum, focusing on particles with surface roughness characterized by self-affine fractal properties. We find that propagating electromagnetic (EM) waves play a dominant role in heat transfer for large particles, while both evanescent EM waves and phononic effects from the area of real contact are important for small particles. As an application, we discuss the heat transfer in rubble pile asteroids.
Article
Multidisciplinary Sciences
Dilara Borte Emiroglu, Aleksandar Bekcic, Dalia Dranseikiene, Xinyu Zhang, Tomaso Zambelli, Andrew J. deMello, Mark W. Tibbitt
Summary: This study investigates the relationship between the macroscopic properties of granular hydrogels and the features of their microgel building blocks using contact mechanics. By studying the mechanics of the microgel packings and modeling the system as a collection of two-body interactions, the researchers were able to accurately describe the rheological properties of the granular hydrogels. These findings provide a rational design framework for improving the engineering of this fascinating class of materials.
Article
Physics, Multidisciplinary
Ran Li, Bao-Lin Liu, Gang Zheng, Hui Yang
Summary: The study shows that the velocity of a particle detector in granular flow is mainly caused by rolling, with the detector having a higher velocity than the surrounding granular flow. The particle image velocimetry (PIV) confirms this phenomenon.
Article
Mechanics
Nhu H. T. Nguyen
Summary: By coupling the volume of fluid and discrete element method, this study investigates impulse waves generated by partially and fully submerged granular collapse. It finds that the relative submerged depth and inter-particle friction are the main factors affecting the maximum wave amplitude, proposing an empirical model and demonstrating its practical application in estimating the maximum wave amplitude of partially submerged landslide events.
Article
Engineering, Mechanical
Longyang Li, Jingfang Zhu, Zhixiang Zeng, Eryong Liu, Qunji Xue
Summary: The study investigates the motion of droplets on a super-hydrophobic surface, the adhesive force, and the angular acceleration in relation to the contact angle. The research shows that the droplets roll instead of slide, and the adhesive force and angular acceleration increase with an increased contact angle. The study also discusses the relationship between etching time, roughness, angular acceleration, and adhesion force of the contact angle.
Article
Engineering, Chemical
Chaofeng Zhang, Xiaoyan Ye
Summary: This paper simulates the impact of a projectile on a granular target using the discrete element method and investigates the resistance force and rheological properties. The study identifies three distinct regions of resistance force and proposes a force model related to penetration depth and angle. Additionally, a rheology model based on packing fraction and inertial number is developed.
Article
Materials Science, Multidisciplinary
Fanjing Meng, Minghua Pang, Shaozhen Hua, Huabo Liu, Lijie Ma
Summary: This study experimentally and numerically investigates the friction behavior of lubricated granular medium. The experimental results show that the nonlinear trend of friction force and friction coefficient with time is influenced by shear velocity and pressure load. The numerical simulation reveals the impact of force chain evolution and granular flow characteristics on friction nonlinearity.
RESULTS IN PHYSICS
(2022)
Article
Environmental Sciences
Arif Jewel, Kazunori Fujisawa, Akira Murakami
Summary: The experiment explores the incipient motion of sands on both sand and smooth beds by estimating bed shear stress through four different indirect methods. Particle image velocimetry was used to study flow dynamics and incipient motion. The critical shear velocity at incipient motion was used to evaluate Manning roughness and Darcy-Weisbach friction coefficients in both sand and smooth zones.
Article
Computer Science, Interdisciplinary Applications
Yutaka Fukumoto, Hongxuan Yang, Tokuzo Hosoyamada, Satoru Ohtsuka
Summary: This paper reports the application of a 2-D coupled fluid-particle simulation model to the seepage failure of saturated granular soils without macroscopic assumptions. The study confirms the feasibility of performing 2-D direct simulation on the scale of a model experiment with soil particles that correspond in size to real sand. The limitations and problems of the proposed method are summarized by comparing with two theories for the critical hydraulic gradient.
COMPUTERS AND GEOTECHNICS
(2021)
Article
Engineering, Geological
Tomohiro Kitao, Yutaka Fukumoto, Kazunori Fujisawa, Arif Jewel, Akira Murakami
Summary: The study investigates the accuracy of pore-scale intergranular flow analysis using the lattice Boltzmann method with the discrete element method, comparing it with experimental results of saturated seepage flows. The results show that the numerical method successfully predicts macroscopic properties obtained in permeability tests, demonstrating the applicability of the LBM-DEM analysis to pore-scale intergranular fluid flows.
Article
Engineering, Geological
Taiki Shimbo, Chisato Shinzo, Ukyo Uchii, Ryota Itto, Yutaka Fukumoto
Summary: This study investigated the effects of water content and initial crack length on the mechanical properties and failure modes of pre-cracked compacted clay under uniaxial compression. The results showed that the unconfined compressive strength decreased with longer initial crack length or higher water content. On the other hand, the deformation modulus was influenced by water content but not by initial crack length. The mode II fracture toughness (K-IIC) was found to depend on water content and empirical correlation formulas were obtained. The failure modes of the compacted clay were classified into five types, with some specimens showing the disappearance of wing cracks and the presence of only secondary cracks due to contact and gliding of the crack surface by shear stress.
ENGINEERING GEOLOGY
(2022)
Article
Agricultural Engineering
Arif Jewel, Kazunori Fujisawa, Akira Murakami
Summary: The study experimentally investigated the effects of injection on bed shear stress and turbulence parameters, revealing that injection led to decreased near-bed velocities, increased velocities near the center of the conduit, and decreased bed stability. Injection also increased the magnitudes of turbulence parameters, with noticeable effects not only in the near-bed region but also across the entire depth range.
PADDY AND WATER ENVIRONMENT
(2022)
Article
Engineering, Multidisciplinary
Vikas Sharma, Kazunori Fujisawa, Akira Murakami, Shuto Sasakawa
Summary: Direct time integration schemes are crucial for the FEM simulation of structural dynamics problems, requiring at least second-order accuracy and unconditional stability. The modified v-ST/FEM developed in this article, based on the time-discontinuous Galerkin method, employs unsymmetric triangular bubble functions to relate displacement and velocity fields. The scheme's accuracy is influenced by the parameters alpha and beta, with alpha affecting accuracy significantly while beta has a negligible impact. The numerical efficacy of the modified v-ST/FEM is demonstrated through solving benchmark problems and comparing results with other popular methods.
INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING
(2022)
Article
Multidisciplinary Sciences
Tomoyuki Murano, Ryuichi Nakajima, Akito Nakao, Nao Hirata, Satoko Amemori, Akira Murakami, Yukiyasu Kamitani, Jun Yamamoto, Tsuyoshi Miyakawa
Summary: The dentate gyrus (DG) plays a critical role in cognitive functions, but its information representation mechanism is not fully understood. In this study, neuronal activity in the DG of freely moving mice was recorded using Ca2+ imaging and analyzed using machine learning. The results showed that multiple types of information can be independently decoded from the activity patterns of DG neurons, and different types of information are encoded by different populations of neurons.
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
(2022)
Article
Computer Science, Interdisciplinary Applications
Quang N. Pham, Satoru Ohtsuka, Koichi Isobe, Yutaka Fukumoto
Summary: This paper estimates the ultimate bearing capacity of rigid strip footings under eccentrically inclined loads using the rigid plastic finite element method. The study considers the effect of soil properties and footing width on the loading planes and clarifies the effect of positive and negative horizontal loads on the limit load space. The results show that the direction of the horizontal load has a notable effect on the bearing capacity, but this effect becomes negligible for large eccentricity lengths.
COMPUTERS AND GEOTECHNICS
(2022)
Article
Computer Science, Interdisciplinary Applications
Yutaka Fukumoto, Taiki Shimbo
Summary: The present paper investigates a 3-D numerical analysis method, combining peridynamics (PD) and the discrete element method (DEM), for handling both the fracture and post-fracture behavior of soil-like materials. The bond-based PD model is used to simulate fracture behavior, while the DEM model calculates the contact forces among fragmented pieces after fracturing. The computational process of physical contact between the wall element and computational nodes is solved based on the DEM. The proposed method shows potential in treating the continuous fracture behavior of soil-like materials in three dimensions.
COMPUTERS AND GEOTECHNICS
(2023)
Article
Engineering, Geological
Tahir Iqbal, Satoru Ohtsuka, Koichi Isobe, Yutaka Fukumoto, Kazuhiro Kaneda
Summary: This study conducted nonlinear finite element analysis using the rigid plastic finite element method (RPFEM) to investigate the difference in the ultimate bearing capacity calculations of surface strip footings between linear and nonlinear shear strength models. A modified ultimate bearing capacity formula was proposed and compared with guidelines from the Architectural Institute of Japan (AIJ) and the Japan Road Association (JRA).
SOILS AND FOUNDATIONS
(2023)
Article
Engineering, Civil
Tahir Iqbal, Satoru Ohtsuka, Koichi Isobe, Yutaka Fukumoto, Kazuhiro Kaneda
Summary: This research mainly focuses on the assessment of the ultimate bearing capacity (UBC) of surface strip footings in sandy soils. It explores the effects of confining stress level and relative density on the shear strength of sandy soils. Non-linear finite element analysis using the rigid plastic finite element method is used to analyze the UBC. The study finds that the ground failure domains are smaller in the case of the non-linear shear strength model compared to the linear one. Additionally, the study compares the analysis results with prevailing guidelines and develops a modified formula for effective stress analysis.
INTERNATIONAL JOURNAL OF GEOMATE
(2023)
Article
Engineering, Geological
S. Ohtsuka, K. Isobe, Y. Fukumoto
Summary: After the 2007 Niigata-ken Chuetsu-Oki Earthquake, a wide-area land subsidence occurred across the Kashiwazaki Plain in Niigata, Japan. Analysis of instantaneous and long-term amounts of land subsidence data revealed that the presence of a marine clay layer greatly influenced the long-term subsidence of the land. The stratified ground subsidence meter and boring survey indicated that a thick clayey layer was the main factor contributing to the subsidence post-earthquake.
GEOTECHNICAL ENGINEERING
(2021)
Article
Engineering, Geological
Haruka Tomobe, Kazunori Fujisawa, Akira Murakami
Summary: This paper introduces a novel approach to measure the shear strength at the root-soil interface under changing suction, proposes a shear strength model, and combines numerical simulation methods. The study demonstrates that the proposed model and approach can accurately predict the shear behavior of root-soil interfaces under changing suction.
SOILS AND FOUNDATIONS
(2021)
Proceedings Paper
Computer Science, Artificial Intelligence
Kazuhiro Nakadai, Yosuke Fukumoto, Ryu Takeda
Summary: This paper investigates node-pruning-based compression for non-uniform deep learning models, such as acoustic models in ASR. The proposed method achieved a 31% speed increase while maintaining the ASR accuracy to be comparable by taking network topology into consideration.
2021 IEEE SPOKEN LANGUAGE TECHNOLOGY WORKSHOP (SLT)
(2021)
