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Search Results: 1 - 10 of 898 matches for " Tomohiro Degawa "
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Vortex Simulation of the Bubbly Flow around a Hydrofoil
Tomomi Uchiyama,Tomohiro Degawa
International Journal of Rotating Machinery , 2007, DOI: 10.1155/2007/72697
Abstract: This study is concerned with the two-dimensional simulation for an air-water bubbly flow around a hydrofoil. The vortex method, proposed by the authors for gas-liquid two-phase free turbulent flow in a prior paper, is applied for the simulation. The liquid vorticity field is discrerized by vortex elements, and the behavior of vortex element and the bubble motion are simultaneously computed by the Lagrangian approach. The effect of bubble motion on the liquid flow is taken into account through the change in the strength of vortex element. The bubbly flow around a hydrofoil of NACA4412 with a chord length 100 mm is simulated. The Reynolds number is 2.5×105, the bubble diameter is 1 mm, and the volumetric flow ratio of bubble to whole fluid is 0.048. It is confirmed that the simulated distributions of air volume fraction and pressure agree well with the trend of the measurement and that the effect of angle of attack on the flow is favorably analyzed. These demonstrate that the vortex method is applicable to the bubbly flow analysis around a hydrofoil.
Behavior of a Jet Issuing Diagonally Upward into Two-Layer Density-Stratified Fluid in a Cylindrical Tank  [PDF]
Tomohiro Degawa, Shota Fukue, Tomomi Uchiyama, Akira Ishikawa, Koji Motoyama
Journal of Flow Control, Measurement & Visualization (JFCMV) , 2017, DOI: 10.4236/jfcmv.2017.53004
Abstract: This study is concerned with the experimental investigation of a jet issuing diagonally upward into a two-layer density-stratified fluid in a cylindrical tank and the resulting mixing phenomena. The upper and lower fluids are water and an aqueous solution of sodium chloride (NaCl), respectively, and the lower fluid issues from a nozzle on the bottom of the tank. The angle between the centerline of the jet and the bottom of the tank is 60o, and the mass concentration of the NaCl solution is 0.02. The investigation reveals that secondary flow is caused by the jet in the horizontal cross-sections of the tank and that it is composed of a pair of vortices. It confirms that the secondary flow at the density interface corresponds to an internal density current. The investigation also clarifies the effect of the Reynolds number of the jet on mixing between the lower and upper fluids.
Numerical Simulation of Jet Issuing Diagonally Upward into Density-Stratified Fluid in Cylindrical Tank  [PDF]
Tomohiro Degawa, Tomomi Uchiyama, Isao Aozasa, Akira Ishikawa, Koji Motoyama
Journal of Power and Energy Engineering (JPEE) , 2018, DOI: 10.4236/jpee.2018.63004
Abstract: This study simulates the behavior of a jet issuing into a two-layer density-stratified fluid in a cylindrical tank and the resulting mixing phenomena. The upper and lower fluids are water and an aqueous solution of sodium chloride (NaCl), respectively, with the lower fluid issuing diagonally upward from a nozzle on the bottom of the tank. The angle between the centerline of the jet and the tank bottom is 60°. The phenomena when the Reynolds number Re of the jet is 475, 1426, and 2614 are simulated. The mass concentration of the aqueous solution of NaCl is 0.02. The simulation successfully grasps the jet behavior and the resulting mixing, which agree with the authors’ experimental results at the corresponding Re value. The secondary flows that appear in the horizontal cross-sections consist of a pair of vortices and flows along the tank wall. The secondary flow at the density interface represents the intrusion of an internal density current, which gives rise to mixing along the interface.
Comparison of lung cancer cell lines representing four histopathological subtypes with gene expression profiling using quantitative real-time PCR
Takashi Watanabe, Tomohiro Miura, Yusuke Degawa, Yuna Fujita, Masaaki Inoue, Makoto Kawaguchi, Chie Furihata
Cancer Cell International , 2010, DOI: 10.1186/1475-2867-10-2
Abstract: We selected 100 genes from public DNA microarray data and examined them by DNA microarray analysis in eight test cell lines (A549, ABC-1, EBC-1, LK-2, LU65, LU99, STC 1, RERF-LC-MA) and a normal control lung cell line (MRC-9). From this, we extracted 19 candidate genes. We quantified the expression of the 19 genes and a housekeeping gene, GAPDH, with qPCR, using the same eight cell lines plus four additional validation lung cancer cell lines (RERF-LC-MS, LC-1/sq, 86-2, and MS-1-L). Finally, we characterized the four subtypes of lung cancer cell lines using principal component analysis (PCA) of gene expression profiling for 12 of the 19 genes (AMY2A, CDH1, FOXG1, IGSF3, ISL1, MALL, PLAU, RAB25, S100P, SLCO4A1, STMN1, and TGM2). The combined PCA and gene pathway analyses suggested that these genes were related to cell adhesion, growth, and invasion. S100P in AD cells and CDH1 in AD and SQ cells were identified as candidate markers of these lung cancer subtypes based on their upregulation and the results of PCA analysis. Immunohistochemistry for S100P and RAB25 was closely correlated to gene expression.These results show that the four subtypes, represented by 12 lung cancer cell lines, were well characterized using qPCR and PCA for the 12 genes examined. Certain genes, in particular S100P and CDH1, may be especially important for distinguishing the different subtypes. Our results confirm that qPCR and PCA analysis provide a useful tool for characterizing cancer cell subtypes, and we discuss the possible clinical applications of this approach.Lung cancer is the leading cause of cancer-related death in men and women worldwide and continues to increase in frequency. Currently, a diagnosis of lung cancer is generally based on histopathological findings. Lung cancers are generally classified as either small-cell lung carcinoma (SC) or non-small-cell lung carcinoma (NSCLC). NSCLC is further classified into three histopathological subtypes: adenocarcinoma (AD), squamous cell
Influences of Diamines on the Morphologies and the Chemical, Thermal, and Mechanical Properties of Polyurethane-Imide Elastomers  [PDF]
Tomohiro Ueda, Tomohiro Nishio, Shinichi Inoue
Open Journal of Organic Polymer Materials (OJOPM) , 2017, DOI: 10.4236/ojopm.2017.74004
Abstract: Polyurethane-imide elastomers (PUIEs) are formed from isocyanate, polyol, acid anhydride, and diamine by liquid polymerization. Unfortunately, many of the diamines have rarely been applied to the formation of PUIEs. Hence, investigating the effect of diamines on PUIEs remains a challenge in polymer chemistry. Herein, PUIEs prepared from 4,4'-diphenylmethane diisocyanate (MDI), polytetramethylene glycol (Mw: 1000), pyromellitic dianhydride, and aromatic diamines (such as p-phenylene diamine, 4,4'-oxydianiline, and 1,3-bis(4-aminophenoxy)benzene), and aliphatic diamines (such as 1,2-ethylene diamine, 1,6-hexamethylene diamine, and 1,12-dodecamethylene diamine) were synthesized by liquid polymerization. The morphologies and the chemical, thermal, and mechanical properties of the various PUIEs were investigated. The obtained elastomeric sheets were characterized in terms of the following tests and methods: solubility and swelling tests, X-ray diffraction and differential scanning calorimetry, dynamic mechanical analysis and thermogravimetric analysis, tensile tests, nuclear magnetic resonance spectroscopy, infrared spectroscopy, atomic force microscopy, contact angle microscopy, and scanning electron microscopy
Nanoscale Equilibrium Crystal Shapes
M. Degawa,F. Szalma,E. D. Williams
Physics , 2004, DOI: 10.1016/j.susc.2005.03.032
Abstract: The finite size and interface effects on equilibrium crystal shape (ECS) have been investigated for the case of a surface free energy density including step stiffness and inverse-square step-step interactions. Explicitly including the curvature of a crystallite leads to an extra boundary condition in the solution of the crystal shape, yielding a family of crystal shapes, governed by a shape parameter c. The total crystallite free energy, including interface energy, is minimized for c=0, yielding in all cases the traditional PT shape (z x3/2). Solutions of the crystal shape for c≠0 are presented and discussed in the context of meta-stable states due to the energy barrier for nucleation. Explicit scaled relationships for the ECS and meta-stable states in terms of the measurable step parameters and the interfacial energy are presented.
Combined effects of knee extension strength, visual acuity, and knee-joint pain on older women’s gait  [PDF]
Tomohiro Demura, Shinichi Demura
Health (Health) , 2013, DOI: 10.4236/health.2013.53060
Abstract:

The purpose of this study was to examine the combined effects of knee extension strength (KES), visual acuity (VA), and knee joint pain (KP) on gait in 212 older women. Including, walking speed, cadence, were selected as gait parameters. Knee extension strength was measured by isometric knee extension strength, while knee joint pain and decreased visual acuity were evaluated by subjective judgment. The combine effect of KP and KES factors was examined. Stance time was significantly longer in persons with both-KP than in persons with no KP. In addition, people with superior KES had significantly greater values in walking speed, cadence, and step length, and lower values in stance time and walking angle than those with inferior KES. Furthermore, double support time showed that persons with both-KP have significantly greater values than persons with no or one-KP in the inferior KES group. Also, persons with the inferior KES had significantly greater values in persons with both-KP. The combine effect of KES and VA factors was examined. There are significant differences between the superior and the inferior KES groups. In conclusion, the elderly with both the factors of decreasing KES and both-KP, as compared to the elderly with just one of those factors, have markedly different gait properties.

R & D-Based Growth Model with Nominal Wage Stickiness  [PDF]
Shunsuke Shinagawa, Tomohiro Inoue
Theoretical Economics Letters (TEL) , 2016, DOI: 10.4236/tel.2016.65089
Abstract: In this study, we introduce nominal wage stickiness into an endogenous growth model based on R & D. This study examines how money growth affects long-run economic growth. We find that there exists a unique balanced growth path for sufficiently high rates of money growth, and that the economy exhibits sustained growth based on sustained R & D. Faster money growth results in greater employment and faster economic growth along such a balanced growth path. Furthermore, under some parameter restrictions, no balanced growth path exists for low rates of money growth; the economy is trapped in a steady state without long-run growth. These results suggest that money growth may be an important factor for long-run economic growth.
Direct Measurement of Medical Linear Accelerator Electron Beam Width at Scattering Foil Position  [PDF]
Tomohiro Shimozato, Yuichi Aoyama
International Journal of Medical Physics,Clinical Engineering and Radiation Oncology (IJMPCERO) , 2017, DOI: 10.4236/ijmpcero.2017.61007
Abstract: Purpose: The aim of this study was to develop a method for the direct measurement of electron beam width and distribution at the scattering foil on the carrousel in a medical linear accelerator gantry head, which differs from an existing indirect method for measuring the focal spot size using a camera or metallic slit located outside the gantry head. Methods: The electron beam emitted by the linear accelerator was used to irradiate radiochromic film mounted on the scattering foil on the carrousel, which was not used for clinical treatment. The electron beam width at the scattering foil position was then evaluated using the full width at half maximum of the Gaussian distribution approximated from each one dimensional distribution of the irradiated radiochromic film. Results: The electron beam width at the scattering foil position was found to be 3.1 to 6.4 mm in the crossline direction and 2.8 to 5.5 mm in the inline direction with electron energy of 4 to 16 MeV. The two-dimensional distribution of the electron beam was therefore elliptical or distorted in shape, not circular. Conclusions: Direct measurement of the electron beam width at the scattering foil in the carrousel of a medical linear accelerator is possible, though the use of lower sensitivity film in addition to indirect methods is expected to bring about better results. However, as this method does not allow for direct measurement of the incident angle of the accelerated electron beam, further improvements and refinements are still needed.
Dose Distributions in Simulated Electron Radiotherapy with Intraoral Cones Using Treatment Planning System  [PDF]
Tomohiro Shimozato, Kuniyasu Okudaira
International Journal of Medical Physics,Clinical Engineering and Radiation Oncology (IJMPCERO) , 2017, DOI: 10.4236/ijmpcero.2017.63025
Abstract: Aim: This study aims to evaluate the difference between depth data from an intraoral cone and a conventional irradiation tube calculated using a treatment planning system (TPS), and that measured using an intraoral cone for electron radiotherapy. Background: A TPS is only compatible with conventional irradiation tubes. However, such systems are not suitable for determining dose distributions when a special cone is employed. Materials and Methods: Dose distributions were calculated using the beam data for mounted intraoral cones using a TPS. Then, the dose distribution by field size was calculated for a low-melting-point lead alloy using the beam data for a mounted conventional tube. The calculated data were evaluated against the measured intraoral-cone depth data based on the dose and depth differences. Results: The calculated data for the intraoral cone case did not match the measured data. However, the depth data obtained considering the field size determined for the lead alloy using the conventional tube were close to the measured values for the intraoral cone case. The difference in the depth at which the absorbed dose was 50% of the maximum value of the percentage depth dose was less than ±4 mm for the generalized Gaussian pencil beam convolution algorithm and less than ±1 mm for the electron Monte Carlo algorithm. Conclusion: It was found that the measured and calculated dose distributions were in agreement, especially when then electron Monte Carlo algorithm was used. Thus, the TPS can be employed to determine dose distributions for intraoral cone applications.
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