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Simulating hydraulic fracturing processes in laboratory-scale geological media using three-dimensional TOUGH-RBSN

Journal of Rock Mechanics and Geotechnical Engineering 2018年第6期10卷 1102-1111页

作者： daisuke asahina Pengzhi Pan Kimikazu Tsusaka Mikio Takeda John E.Bolander Geological Survey of Japan IbarakiJapan State Key Laboratory of Geomechanics and Geotechnical Engineering Institute of Rock and Soil MechanicsChinese Academy of SciencesWuhan430071China INPEX Corporation TokyoJapan University of California DavisUSA

In this context, recent developments in the coupled three-dimensional(3 D) hydro-mechanical(HM)simulation tool TOUGH-RBSN are presented. This tool is used to model hydraulic fracture in geological media, as observed in laboratory-scale tests. The TOUGH-RBSN simulator is based on the effective linking of two numerical methods: TOUGH2, a finite volume method for simulating mass transport within a permeable medium; and a lattice model based on the rigid-body-spring network(RBSN) concept. The method relies on a Voronoi-based discretization technique that can represent fracture development within a permeable rock matrix. The simulator provides two-way coupling of HM processes, including fluid pressure-induced fracture and fracture-assisted flow. We first present the basic capabilities of the modeling approach using two example applications, i.e. permeability evolution under compression deformation, and analyses of a static fracturing simulation. Thereafter, the model is used to simulate laboratory tests of hydraulic fracturing in granite. In most respects, the simulation results meet expectations with respect to permeability evolution and fracturing patterns. It can be seen that the evolution of injection pressure associated with the simulated fracture developments is strongly affected by fluid viscosity.

关键词： Hydraulic fracture Crack opening TOUGH Rigid-body-spring network(RBSN) Permeability Injection pressure Fluid viscosity Hydro-mechanical(HM) processes

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On base manifolds of Lagrangian fibrations

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Science China Mathematics 2015年第3期58卷 531-542页

作者： MATSUSHITA daisuke Department of Mathematics Hokkaido University

We consider base spaces of Lagrangian fibrations from singular symplectic varieties. After defining cohomologically irreducible symplectic varieties, we construct an example of Lagrar, gian fibration whose base space is isomorphic to a quotient of the projective space. We also prove that the base space of Lagrangian fibration from a cohomologically symplectic variety is isomorphic to the projective space provided that the base space is smooth.

关键词： Lagrangian fibration singularity base manifolds symplectic varieties

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Relationship between space charge and effective pore size of nanoporous electrode in electric double-layer capacitor

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Particuology 2011年第1期9卷 91-94页

作者： daisuke Tashima Masahisa Otsubo Interdisciplinary Research Organization University of Miyazaki 1-1 Gakuenkibanadai-Nishi 1-1 Miyazaki 889-2192 Japan Department of Electrical and Electronic Engineering Faculty of Engineering University of Miyazaki 1-1 Gakuenkibanadai-Nishi 1-1 Miyazaki 889-2192 Japan

The space-charge distributions of electric double-layer capacitors （EDLCs）, which are energy storage devices, were examined with the pulsed electroacoustic （PEA） method. It was found that the experimental results could be influenced by the reflection and penetration of sound waves when the space-charge dis- tributions of EDLCs were measured with the PEA method. This is because EDLCs have a five-layer structure consisting of three materials （aluminum, cellulose, and activated carbon）. We calculated the reflection wave components that influenced the charge density through the acoustic impedance and the relative permittivity of the materials. In this way, we found that the changes in the space-charge distributions of EDLCs and their charge characteristics corresponded closely. We determined that measuring the space- charge distributions with the PEA method was effective for evaluating the charge accumulation of EDLCs. In this study, a polarized electrode was prepared for use in EDLCs. The ratio of the surface area to the average pore diameter of the polarized electrode was measured with the nitrogen adsorption method at 77 K. The relationship between the ratio of the surface area to the average pore size and the space-charge distributions of EDLCs is also discussed in this paper.

关键词： Electric double-layer capacitors Pulsed electroacoustic method Pore size

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Artificial Pheromone System Using RFID for Navigation of Autonomous Robots

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Journal of Bionic Engineering 2007年第4期4卷 245-253页

作者： Herianto Toshiki Sakakibara daisuke Kurabayashi Tokyo Institute of Technology Tokyo 152-8552 Japan

Navigation system based on the animal behavior has received a growing attention in the past few years. The navigation systems using artificial pheromone are still few so far. For this reason, this paper presents our research that aim to implement autonomous navigation with artificial pheromone system. By introducing artificial pheromone system composed of data carriers and autonomous robots, the robotic system creates a potential field to navigate their group. We have developed a pheromone density model to realize the function of pheromones with the help of data carders. We intend to show the effectiveness of the proposed system by performing simulations and realization using modified mobile robot. The pheromone potential field system can be used for navigation of autonomous robots.

关键词： artificial pheromone RFID indirect communication autonomous robot navigation

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Quantitative Analysis of the Silk Moth＇s Chemical Plume Tracing Locomotion Using a Hierarchical Classification Method

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Journal of Bionic Engineering 2014年第2期11卷 268-281页

作者： Jouh Yeong Chew daisuke Kurabayashi Department of Mechanical and Control Engineering Tokyo Institute of Technology 152-8552 Tokyo Japan

The silk moth （Bombyx mori） exhibits efficient Chemical Plume Tracing （CPT）, which is ideal for biomimetics. However, there is insufficient quantitative understanding of its CPT behavior. We propose a hierarchical classification method to segment its natural CPT locomotion and to build its inverse model for detecting stimulus input. This provides the basis for quantitative analysis. The Gaussian mixture model with expectation-maximization algorithm is used first for unsupervised classification to decompose CPT locomotion data into Gaussian density components that represent a set of quantified elemental motions. A heuristic behavioral rule is used to categorize these components to eliminate components that are descriptive of the same motion. Then, the echo state network is used for supervised classification to evaluate segmented elemental motions and to compare CPT locomotion among different moths. In this case, categorized elemental motions are used as the training data to estimate stimulus time. We successfully built the inverse CPT behavioral model of the silk moth to detect stimulus input with good accuracy. The quantitative analysis indicates that silk moths exhibit behavioral singularity and time dependency in their CPT locomotion, which is dominated by its singularity.

关键词： biomimetics recognition learning and adaptive systems chemical plume tracing quantitative analysis

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Extraction,classification and visualization of 3-dimensional clouds simulated by cloud-resolving atmospheric model

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International Journal of Modeling, Simulation, and Scientific Computing 2017年第4期8卷 190-204页

作者： daisuke Matsuoka Center for Earth Information Science and Technology(CEIST)Japan Agency for Marine-Earth Science and Technology(JAMSTEC)3173-25 Showa-Machi Kanazawa-kuYokohama 236-0001Japan

Cloud-resolving atmospheric general circulation models using large-scale supercomputers reproduce realistic behavior of 3-dimensional atmospheric field on a global *** understand the simulation result for scientists,conventional visualization methods based on 2-dimensional cloud classification are not enough for understanding individual clouds and their physical *** this study,we propose a new 3-dimensional extraction and classification method of simulated clouds based on their 3-dimensional shape and physical *** proposed method extracts individual clouds by cloud water and cloud ice,and classifies them into six types by their altitude and upward *** applied the method to time-varying atmospheric simulation data,and attempted to visualize atmospheric phenomena on the tropics such as developing cumulonimbus and tropical *** case studies clearly visualize the behavior of individual cloud type and clarify that some cloud types have a relationship with rainfall during active weather *** proposed method has the potential to analyze such phenomena that develop in the vertical direction as well as the horizontal direction.

关键词： Atmospheric simulation cloud visualization

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Partitioned Method of Insect Flapping Flight for Maneuvering Analysis

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Computer Modeling in Engineering & Sciences 2019年第10期121卷 145-175页

作者： Minato Onishi daisuke Ishihara Kyushu Institute of Technology 680-4 KawazuIizuka Fukuoka820-8502Japan

This study proposed a partitioned method to analyze maneuvering of insects during flapping *** method decomposed the insect flapping flight into wing and body subsystems and then coupled them via boundary conditions imposed on the wing’s base using one-way *** the wing subsystem,the strong coupling of the flexible wings and surrounding fluid was accurately analyzed using the finite element method to obtain the thrust forces acting on the insect’s *** resulting thrust forces were passed from the wing subsystem to the body subsystem,and then rigid body motion was analyzed in the body *** rolling,yawing,and pitching motions were simulated using the proposed method as follows:In the rolling simulation,the difference of the stroke angle between the right and left wings caused a roll *** the yawing simulation,the initial feathering angle in the right wing only caused a yaw *** the pitching simulation,the difference between the front-and back-stroke angles in both the right and left wings caused a pitch *** three torques generated maneuvering motion comparable with that obtained in actual observations of insect *** results demonstrate that the proposed method can adequately simulate the fundamental maneuvers of insect flapping *** the present simulations,the maneuvering mechanisms were investigated at the governing equation level,which might be difficult using other ***,the proposed method will contribute to revealing the underlying insect flight mechanisms.

关键词： Insect flapping flight maneuverability fluid-structure interaction partitioned method projection method strongly coupled method one-way coupling finite element method

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Unsteady Behavior of Surge and Rotating Stall in an Axial Flow Compressor

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Journal of Thermal Science 2012年第4期21卷 302-310页

作者： Yutaka OHTA Yutaka FUJITA daisuke MORITA Department of Applied Mechanics and Aerospace Engineering Waseda University 3-4-1 Okubo Shinjuku Graduate Student Graduate School of Science and Engineering Waseda University 3-4-1 Okubo Shinjuku

Unsteady behaviors as well as unsteady cascade flow fields of a single-stage axial flow compressor were experi- mentally investigated by detail measurements of unsteady performance characteristics and casing wall pressure and internal flow velocity fluctuations. The main feature of the test compressor is a capacity tank connected di- rectly to the compressor outlet in series through slits and a concentric duplex pipe, and also jet nozzles in order to inject compressed air toward the rotor tip region. Research attention is focused on the post-stall characteristics of surge and rotating stall which occur simultaneously. When the compressor was connected to the capacity tank, surge was generated with rotating stall in accordance with the capacitance increment of whole compressor system The surge behavior changed irregularly with throttling valve installed behind the compressor, and several types of surge cycles were observed. In addition, the surge cycle changed by jet injection to the rotor tip region. The re- suits suggested that the blockages of the cascade flow which were generated by a stall cell play an important role in deciding the surge behaviors.

关键词： Axial flow compressor Surge Rotating stall Stall cell Jet injection

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Deviation of congruent composition in Fe-Pd system

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Rare Metals 2006年第5期25卷 393-398页

作者： Tetsuo Mohri daisuke Hamajima Ying Chen Division of Materials Science and Engineering Graduate School of Engineering Hokkaido University Kita-13 Nishi-8 Kita-ku Sapporo 060-8628Japan Department of Quantum Engineering and System Science Graduate School of Engineering University of Tokyo Hongo 7-3-1 Bunkyo-ku Tokyo113-8656 Japan

The first-principles calculation of the disordered Ll0 phase boundary for the Fe-Pd system is attempted by combining the FLAPW electronic structure total energy calculations and the cluster variation method via the cluster expansion method. The lattice vibration effects are taken into account based on the Debye-Gruneisen model within quasi-harmonic approximation. The transition temperature is reproduced with very high accuracy. However, the experimental congruent composition of disordered L10 phase that significantly deviates from 1.＂ 1 stoichiometry is not reproduced. Fulther calculations are attempted based on the phenomenological Lennard-Jones type pair potential, which is capable of introducing both tetragonality of the Ll0 ordered phase and additional configurational freedom because of the magnetic spins. The prelimi- nary calculations indicate that the tetragonality enhances the stability of the L10 ordered phase and the magnetic contributions also change the transition temperature. Despite these findings, the shift of the congruent composition still remains as a subject that needs further research. The electronic origin of the shifting of the congruent composition is briefly discussed.

关键词： Fe-Pd alloy system order-disorder phenomena phase diagrams ab initio calculation

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Dilute long period stacking/order(LPSO)-variant phases along the composition gradient in a Mg-Ho-Cu alloy

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Journal of Magnesium and Alloys 2022年第6期10卷 1573-1580页

作者： Kai Guan daisuke Egusa Eiji Abe Department of Materials Science and Engineering The University of TokyoTokyo 113-8656Japan Research Center for Structural Materials National Institute for Materials ScienceTsukuba 305-0047Japan

We have systematically investigated the microstructures of as-cast Mg_(97.49)Ho_(1.99)Cu_(0.43)Zr_(0.09)alloy by atomic resolution high-angle annular dark field scanning transmission electron microscopy(HAADF-STEM), revealing the coexistence of 18R, 14H and 24R long period stacking/order(LPSO) phases with fully coherent interfaces along step-like composition gradient in a blocky intermetallic compound distributed at grain boundary. The short-range order(SRO) L1_(2)-type Cu_(6)Ho_(8)clusters embedded across AB’C’A-stacking fault layers are directly revealed at atomic scale. Importantly, the order degree of SRO clusters in the present dilute alloy is significant lower than previous 6M and 7M in-plane order reported in ternary Mg-TM(transition metal)-RE(rare earth) alloys, which can be well matched by 9M in-plane order. This directly demonstrates that SRO in-plane L1_(2)-type clusters can be expanded into more dilute composition regions bounded along the definite TM/RE ratio of 3/4. In addition, the estimated chemical compositions of solute enriched stacking fault(SESF) in all LPSO variants are almost identical with the ideal SESF composition of 9M in-plane order, regardless of the type of LPSO phases. The results further support the viewpoint that robust L1_(2)-type TM_(6)RE_(8)clusters play an important role in governing LPSO phase formation.

关键词： Magnesium alloys Long period stacking/order(LPSO)phases Short-range order(SRO)clusters High-angle annular dark field scanning transmission electron microscopy(HAADF-STEM)

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