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SH-wavefield simulation for a laterally heterogeneous whole-Earth model using the pseudospectral method

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Science China Earth Sciences 2011年第12期54卷 1940-1947页

作者： WANG YanBin TAKENAKA hiroshi Department of Geophysics School of Earth and Space Sciences Peking University Beijing 100871 China Department of Earth and Planetary Sciences Kyushu University Hakozaki 6-10-1 Fukuoka 812-8581 Japan

We present a scheme to simulate SH-wave propagation in a whole-Earth model with arbitrary lateral heterogeneities employing the Fourier pseudospectral method. Wave equations are defined in two-dimensional cylindrical coordinates and the model is taken through a great circle of the Earth. Spatial derivatives in the wave equations are calculated in the wavenumber domain by multiplication, and the transformation between spatial and wavenumber domains is performed via fast Fourier transformation. Because of the high accuracy and high speed of the Fourier pseudospectral method, the scheme enables us to calculate a short-wavelength global SH-wavefield with accurate waveforms and arrival times for models with heterogeneities that can be approximated as azimuthally symmetric. Comparing with two-dimensional simulation methods based on an axisymmetric model, implementing the seismic source in the present scheme is more convenient. We calculated the global SH-wavefield for the preliminary reference Earth model to identify the generation, reflection and refraction of various seismic phases propagating in the Earth. Applications to a heterogeneous global model with low-velocity perturbation above the core-mantle boundary were conducted to analyze the effect of lateral heterogeneity on global SH-wave propagation.

关键词： wave propagation computational seismology pseudospectral method global seismology core-mantle boundary

Linear seesaw model with a modular S_(4)flavor symmetry

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Chinese Physics C 2022年第5期46卷 11-19页

作者： Takaaki Nomura hiroshi Okada College of Physics Sichuan UniversityChengdu 610065China Asia Pacific Center for Theoretical Physics(APCTP)-Headquarters San 31 Hyoja-dongNam-guPohang 790-784Korea Department of Physics Pohang University of Science and TechnologyPohang 37673Korea

We discuss a linear seesaw model with a field content as minimum as possible,introducing a modular S_(4)using gauged U(1)_(B−L) *** to the rank two neutrino mass matrix,we obtain a vanishing neutrino mass eigenvalue,and only the normal mass hierarchy of neutrinos is favored via the modular S_(4)*** our numericalΔχ^(2)analysis,we especially determine a relatively sharp prediction on the sum of neutrino masses to be approximately 60 meV,in addition to other predictions.

关键词： neutrino mass linear seesaw mechanism modular S_(4)flavor symmetry

Hydrodynamic performance of spouted beds with different types of draft tubes

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Particuology 2013年第5期11卷 475-482页

作者： hiroshi Nagashima Kazumi Suzukawa Toshifumi Ishikura Department of Chemical Engineering Fukuoka University19-1Nanakuma 8-chomeJonan-kuFukuoka 814-0180Japan

Hydrodynamic performance of spouted beds with four different types of draft tubes has been investigated experimentally. In this work, irregular and angular particles were used as the spouting solids and the results were compared with those of the previous work in which regular and round particles had been used. It was found that the conical-cylindrical porous draft tube was the best option for solid-gas contact and solids circulation as in the case of round particles. Moreover, by using conical-cylindrical porous draft tube, the gas flow rate through the annulus reached 65-70%, equal to the level of a conventional spouted bed.

关键词： Spouted bedConical-cylindrical porous draft tubeAngular sandGas-solid contactSolids circulation rate

One-Dimensional Analysis of Supersonic Two-Stage HVOF Process

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Journal of Thermal Science 2009年第4期18卷 332-337页

作者： hiroshi KATANODA Junichi HAGI Minoru FUKUHARA Dept.Mechanical Engineering Kagoshima University

The one-dimensional calculation of the gas/particle flows of a supersonic two-stage high-velocity oxy-fuel(HVOF) thermal spray process was performed. The internal gas flow was solved by numerically integrating theequations of the quasi-one-dimensional flow including the effects of pipe friction and heat transfer. As for the supersonicjet flow, semi-empirical equations were used to obtain the gas velocity and temperature along the centerline. The velocity and temperature of the particle were obtained by an one-way coupling method. The material ofthe spray particle selected in this study is ultra high molecular weight polyethylene (UHMWPE). The temperaturedistributions in the spherical UHMWPE particles of 50 and 150 m accelerated and heated by the supersonic gasflow was clarified.

关键词： Compressible Flow Supersonic Flow Two-Stage HVOF Thermal Spray One-Dimensional Analysis UHMWPE

Experimental Study on Shock Wave Structures in Constant-area Passage of Cold Spray Nozzle

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Journal of Thermal Science 2007年第1期16卷 40-45页

作者： hiroshi KATANODA Takeshi MATSUOKA Kazuyasu MATSUO Dept.Mechanical Engineering Kagoshima University1-21-40 KorimotoKagoshima890-0065 Japan Takagi Precision Dies Co. Ltd.2-4-1 Ishida-MinamiMinami-kuKitakyushuFukuoka802-0836 Japan Dept.Mechanical Systems and Environmental Engineering The University of Kitakyushu1-1 HibikinoWakamatsukuKitakyushuFukuoka808-0135 Japan

Cold spray is a technique to make a coating on a wide variety of mechanical or electric parts by spraying solid particles accelerated through a high-speed gas flow in a converging-diverging nozzle. In this study, pseudo-shock waves in a modeled cold spray nozzle as well as high-speed gas jets are visualized by schlieren technique. The schlieren photographs reveals the supersonic flow with shock train in the nozzle. Static pressure along the barrel wall is also measured. The location of the head of pseudo-shock wave and its pressure distribution along the nozzle wall are analytically explained by using a formula of pseudo-shock wave. The analytical results show that the supersonic flow accompanying shock wave in the nozzle should be treated as pseudo-shock wave instead of normal shock wave.

关键词： Supersonic Flow Pseudo-Shock Wave Jet Flow Cold Spray

Numerical Simulation on Supersonic Flow in High-Velocity Oxy-Fuel Thermal Spray Gun

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Journal of Thermal Science 2006年第1期15卷 65-70页

作者： hiroshi KATANODA Hideki YAMAMOTO Kazuyasu MATSUO The University of Kitakyushu 1-1 Hibikino Wakamatsu-ku Kitakyushu Fukuoka 808-0135 Japan

This paper analyzes the behaviour of coating particles as well as the gas flow both inside and outside of the High-Velocity Oxy-Fuel （HVOF） thermal spray gun by using a quasi-one-dimensional analysis and a numerical simulation. The HVOF gun in the present analysis is an axially symmetric convergent-divergent nozzle with the design Math number of 2.0. From the present analysis, the distributions of veloeity and temperature of the coating particles flying inside and outside of the HVOF gun are predicted. The velocity and temperature of the coating particles at the exit of the gun calculated by the present method agree well with the previous experimental results. Therefore, the present method of calculation is considered to be useful for predicting the HVOF gas and particle flows.

关键词： compressible flow supersonic jet thermal spray HVOF.

Analysis of Particle Behavior in High-Velocity Oxy-Fuel Thermal Spraying Process

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Journal of Thermal Science 2003年第3期12卷 279-282页

作者： hiroshi Katanoda Kazuyasu Matsuo Department of Mechanical Systems and Environmental Engineering Faculty of Environmental EngineeringThe University of Kitakyushu1-1 HibikinoWakamatu-kuKitakyushuFukuoka808-0135JapanDepartment of Mechanical Systems and Environmental EngineeringFaculty of Environmental EngineeringThe University of Kitakyushu1-1 HibikinoWakamatu-kuKitakyushuFukuoka808-0135Japan

This paper analyzes the behavior of coating particle as Well as the gas flow both of inside and outside the High-Velocity Oxy-Fuel (HVOF) thermal spraying gun by using quasi-one-dimensional analysis and numerical simulation. The HVOF gun in the present analysis is an axisymmetric convergent-divergent nozzle with the design Mach number of 2.0 followed by a straight passage called barrel. In the present analysis it is assumed that the influence of the particles injected in the gas flow is neglected, and the interaction between the particles is also neglected. The gas flow in the gun is assumed to be quasi-one-dimensional adiabatic flow. The velocity, temperature and density of gas in the jet discharged from the barrel exit are predicted by solving Navier-Stokes equations numerically. The particle equation of motion is numerically integrated using three-step Runge-Kutta method. The drag coefficient of the particle is calculated by linear interpolation of the experimental data obtained in the past. Particle mean temperature is calculated by using Ranz and Marchalls' correlation for spherical particles. From the present analysis, the distributions of velocity and temperature of the coating particles flying inside and outside the HVOF gun are predicted.

关键词： supersonic nozzle supersonic jet thermal spraying gas-particle flow.

Effectiveness of a 12-Week Program of Active and Passive Stretching in Improving Low Back and Neck Pain in Japanese Sedentary Men

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Health 2017年第3期9卷 493-505页

作者： Yuna Naraoka Mikiyuki Katagiri Takuji shirasawa shirasawa Anti-Aging Medical Institute Tokyo Japan Japanese Center for Research on Woman in Sport Juntendo University Tokyo Japan

Purpose: Muscle stretching is frequently prescribed in physical therapy to manage lower back and neck pain. However, there is no clear evidence regarding the differences in effectiveness of active and passive stretching. Therefore, we aimed to evaluate the relative effectiveness of a 12-week program of active and passive stretching on selected physical and mental stress variables of sedentary men with lower back and neck pain. Methods: A cohort of 28 sedentary men, 30 - 49 years old, were divided into two intervention groups: the passive stretching group (PSG, n = 15) and the active stretching group (ASG, n = 13). A trainer assisted with static passive stretching, while participants in the ASG were provided with an instructional video. The following outcomes were measured at the start and end of the first and twelfth week of the stretching program: physical measures (visual analogue scale score of lower back and neck pain;finger-to-floor distance, gravimetric assessment of pelvic tilt, muscle hardness of the biceps femoris, and straight-leg raising) and mental stress measures (α-amylase and cortisol levels in saliva samples). Results: Although both active and passive stretching produced acute changes in lower back and neck pain, only passive stretching yielded long-term improvement in pain, finger-to-floor distance, pelvic tilt, hardness of biceps femoris muscle and cortisol levels (p Conclusion: Passive stretching is superior to active stretching in reducing pain, increasing muscle extensibility and correcting posture among a group of sedentary men with lower back and neck pain.

关键词： Active Stretching Passive Stretching Lower Back Pain Neck Pain

Homogeneity tests on neutron shield concrete

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Nuclear Science and Techniques 2014年第A1期25卷 57-61页

作者： Koichi Okuno hiroshi Iikura HAZAMA ANDO Technical Research Institute 515-1 Karima Tsukuba Ibaraki 305-0822 Japan JAEA Quantum Beam Science Directorate 2-4 Shirakata Tokai-mura Naka-gun Ibaraki 319-1195 Japan

In recent years, neutrons have been studied for application in fields such as material analysis and boron neutron capture therapy. To create a compact shield for these facilities, a neutron shield concrete is developed. Verifying the homogeneity of the concrete is important to ensure adequate shielding performance. In this research, neutron radiography images of the concrete are taken using the Thermal Neutron Radiography Facility (TNRF) of the JRR-3 research reactor, and the transmission ratio of the thermal neutrons were estimated. The results showed that the transmission ratio of the concrete was almost the same at each depth. © 2014, Science Press. All rights reserved.

关键词：中子屏蔽同质性测试研究反应堆中子俘获屏蔽性能照相设备中子照相