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Experiment and Large-Eddy Simulation on Free Air Jets Issuing from a Rectangular Nozzle with Deflectors

Journal of Flow Control, Measurement & Visualization 2021年第4期9卷 73-92页

作者： Riku Ouchi Takahiro Kiwata Naoki Kajitani hiroshi teramoto Graduate School of Natural Science and Technology Kanazawa University Ishikawa Japan Thermal Management Systems R&D Div. DENSO CORP Aichi Japan School of Mechanical Engineering Kanazawa University Ishikawa Japan Department of Mechanical Engineering National Institute of Technology Ishikawa College Ishikawa Japan

The purpose of the present study was to establish a passive flow control method for a rectangular jet using two types of deflectors installed symmetrically inside a nozzle. This deflector in a rectangular nozzle generates the rectangular coaxial jets. The effect of the slant angle of the deflectors on the flow characteristics and the spread of the rectangular jet was investigated experimentally and by large-eddy simulation. The experiment and the numerical simulation were carried out at a Reynolds number of 9000. The rectangular jet with no deflectors generates a vortex ring from the nozzle exit. The vortex ring collapses in the downstream region and the outline of the jet changes from rectangular to diamond-shaped as a result of the axis-switching phenomenon. The rectangular jet with divergent and convergent deflectors shows particularly noticeable changes in the flow characteristics and vortical structures, as compared to the case with no deflectors. In the case of the rectangular jet with divergent deflectors (slant angle of α = 6°), minor axis spread is promoted more than major axis spread, and axis switching occurs closer to the nozzle exit than that in the case of no deflectors. The outline of the jet also changes from lateral rectangular to vertical rectangular as a result of axis switching. On the other hand, in the case of a rectangular jet with convergent deflectors (α = -6°), minor axis spread is suppressed more than major axis spread, and axis switching occurs farther from the nozzle exit than that in the case with no deflectors. The outline of the jet does not change until the downstre

关键词： Jet Rectangular Nozzle Deflectors Flow Control Flow Measurement Numerical Simulation LES

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Effective use of the Japan Narrow Band Imaging Expert Team classification based on diagnostic performance and confidence level

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World Journal of Clinical Cases 2019年第18期7卷 2658-2665页

作者： Daizen Hirata hiroshi Kashida Mineo Iwatate Tomomasa Tochio Akira teramoto Yasushi Sano Masatoshi Kudo Gastrointestinal Center and Institute of Minimally-invasive Endoscopic Care Sano HospitalKobe 6550031Japan Department of Gastroenterology and Hepatology Kindai UniversityOsaka 5895811Japan

Five years have passed since the Japan Narrow Band Imaging Expert Team (JNET) classification was proposed in 2014. However, the diagnostic performance of this classification has not yet been established. We conducted a retrospective study and a systematic search of Medical Literature Analysis and Retrieval System On-Line. There were three retrospective single center studies about the diagnostic performance of this classification. In order to clarify this issue, we reviewed our study and three previous studies. This review revealed the diagnostic performance in regards to three important differentiations.(1) Neoplasia from non-neoplasia;(2) malignant neoplasia from benign neoplasia;and (3) deep submucosal invasive cancer (D-SMC) from other neoplasia. The sensitivity in differentiating neoplasia from non-neoplasia was 98.1%-99.8%. The specificity in differentiating malignant neoplasia from benign neoplasia was 84.7%-98.2% and the specificity in the differentiation D-SMC from other neoplasia was 99.8%-100.0%. This classification would enable endoscopists to identify almost all neoplasia, to appropriately determine whether to perform en bloc resection or not, and to avoid unnecessary surgery. This article is the first review about the diagnostic performance of the JNET classification. Previous reports about the diagnostic performance have all been retrospective single center studies. A large-scale prospective multicenter evaluation study is awaited for the validation.

关键词： Japan Narrow Band Imaging Expert Team Classification Magnifying endoscopy Narrow-band imaging Validation Diagnostic performance Colonoscopy Colorectal neoplasms

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Computationally Efficient Large-Eddy Simulation of Periodic Unsteady Flow using Harmonic Balance Method

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Journal of Thermal Science 2022年第1期31卷 62-71页

作者： YUMA Iwamoto SUSUMU teramoto KOJI Okamoto Department of Aeronautics and Astronautics University of TokyoTokyo 113-8656Japan Department of Advanced Energy University of TokyoTokyo 113-8656Japan

To improve the efficiency and fidelity of the numerical analysis for cascade flutter, we propose an efficient scale-resolving simulation method dedicated to time-periodic flows by incorporating the harmonic balance approach into the large-eddy simulation. This method combined convergence calculations of the steady-state problem based on the harmonic balance method for periodic components, and the nonlinear time-marching method for turbulent fluctuations. Using the proposed method, deterministic periodic components and stochastic turbulent fluctuations were calculated simultaneously, and the effect of turbulent fluctuations on deterministic periodic components was directly calculated without using turbulence models. In this paper, we explain the algorithm and feature of this simulation technique and present the results of the computation for channel flow excited in the streamwise direction as an analysis example using the proposed method. In order to validate the proposed method, an analysis of sinusoidally pulsating channel flow at the central friction-velocity Reynolds numbers Rer = 180 was conducted, confirming that the amplitude and phase of the mean velocity oscillation computed by the proposed method were in good agreement with those of the conventional LES. The present calculation achieved an order of magnitude improvement in computational efficiency compared to conventional LES.

关键词： harmonic balance LES turbulent channel flow

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A Deep Learning-Based Phenotypic Analysis of Rice Root Distribution from Field Images

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Plant Phenomics 2020年第1期2卷 324-333页

作者： S.teramoto Y.Uga Institute of Crop Science National Agriculture and Food Research Organization2-1-2 KannondaiTsukubaIbaraki 305-8518Japan

Root distribution in the soil determines plants’nutrient and water uptake ***,root distribution is one of the most important factors in crop *** trench profile method is used to observe the root distribution underground by making a rectangular hole close to the crop,providing informative images of the root distribution compared to other root phenotyping ***,much effort is required to segment the root area for *** this study,we present a promising approach employing a convolutional neural network for root segmentation in trench profile *** defined two parameters,Depth50 and Width50,representing the vertical and horizontal centroid of root distribution,*** parameters for root distribution in rice(Oryza sativa L.)predicted by the trained model were highly correlated with parameters calculated by manual *** results indicated that this approach is useful for rapid quantification of the root distribution from the trench profile *** the trained model,we quantified the root distribution parameters among 60 rice accessions,revealing the phenotypic diversity of root *** conclude that employing the trench profile method and a convolutional neural network is reliable for root phenotyping and it will furthermore facilitate the study of crop roots in the field.

关键词： soil Root distribution

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Thermal Characteristic Identification of an Alcohol Flame by Measuring its Density Gradient in Shack-Hartmann Optical System

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Journal of Thermal Science 2011年第1期20卷 93-96页

作者： Md.T.I.Khan K.teramoto Department of Mechanical Engineering Saga University1 HonjoSaga 840-8502Japan

Understanding the flame structure for different combustion in industries has drawn the increasing attention around the ***,for increasing the recent interest of using the hydrogen fuelled vehicles in recent world,structural analysis of flame in combustion chamber has attracted the attention of ***,the high flame temperature and strong flame emissions increase the experimental difficulties,especially,in all kinds of intrusive measurement systems for determining the flame structures and flame ***,a non-intrusive laser interferometer technique based on Shack-Hartmann optical system has been proposed to measure the thermal characteristic of a flame *** the present study,a low-stretched diffusion flame of methanol burner has been ***-Hartmann optical system is a type of wave front *** is commonly used in adaptive optical *** consists of an array of lenses to focus the image onto a photon sensor (photo-detector) at the focal plane and measures the wave front *** major objective of the present study is to develop a laser interferometer measurement technique for analyzing the flame structure and its temperature propagation by measuring the density gradient of the *** interferometer technique is a potential candidate for the non-invasive *** the present paper,a novel method for the measurement of density gradient in flame by using Shack-Hartmann optical system is proposed.A collimated laser beam that has been passed through the flame is tilted due to the density gradient inside the flame.A CCD camera (CCD photo sensor) has been used to observe the wave front tilts at the focal plane.

关键词： Laser Interferometer Density Gradient Shack-Hartmann Optical System Thermal Characteristics Alcohol Flame.

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Pattern Formations in Heat Convection Problems

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Chinese Annals of Mathematics,Series B 2009年第6期30卷 769-784页

作者： Takaaki NISHIDA Yoshiaki teramoto Department of Mathematics Waseda UniversityTokyo 169-8555Japan Department of Mathematics and Physics Setsunan UniversityNeyagawa 572-8508Japan

After Bénard＇s experiment in 1900, Rayleigh formulated heat convection problems by the Oberbeck-Boussinesq approximation in the horizontal strip domain in 1916. The pattern formations have been investigated by the bifurcation theory, weakly nonlinear theories and computational approaches. The boundary conditions for the velocity on the upper and lower boundaries are usually assumed as stress-free or no-slip. In the first part of this paper, some bifurcation pictures for the case of the stress-free on the upper boundary and the no-slip on the lower boundary are obtained. In the second part of this paper, the bifurcation pictures for the case of the stress-free on both boundaries by a computer assisted proof are verified. At last., Bénard-Marangoni heat convections for the ease of the free surface of the upper boundary are considered.

关键词： Oberbeck-Boussinesq equation Heat convection Pattern formation Computer assisted proof

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Jet Screech Reduction with Perforated Flat Reflector

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Journal of Thermal Science 2008年第3期17卷 224-227页

作者： Md.Tawhidul Islam Khan Kenbu teramoto Shigeru Matsuo Toshiaki Setoguchi Department of Mechanical Engineering Saga University

In the present experimental study, investigations have been carded out to evaluate the performance of the new control technique of jet screech with different perforated flat reflectors. Mainly two types of porous flat reflectors had been used in the experiment. One reflector （reflector-V） designed for placing the reflector surface vertical to the jet axis, when, another type of reflector （reflector-H） designed for placing the reflecting surface horizontal to the jet axis. In both cases the reflectors had been placed at the nozzle （base tube with uniform cross-sectional area） exit. The diameter of the reflector-V was 15D when the diameter of the reflector-H was 10D. The porous area of the reflector-V was 6D and 4.5D for reflector-H where D indicated the diameter of the nozzle exit. The placement of the reflector at the exit of the nozzle reduces the sound pressure at the nozzle exit. Thus the muted sound can not excite the unstable disturbance at the nozzle exit and the loop of the feedback mechanism disappeared, finally, the generation of jet screech be cancelled. The suction space located at the back side of the porous surface of the reflector-V improves the efficiency of the screech control technique. However, in the case of reflector-H, the receptivity process of feedback loop had been controlled by reducing the disturbances at the effective shock fronts as well as at the nozzle exit. The performance of the proposed method was verified with a flat reflector concept and good performance in jet screech suppression has been confirmed in the case of porous reflector.

关键词： Supersonic jet noise screech tone feedback loop noise reduction porous reflector

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Hemodynamic consideration of intracranial aneurysm

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Translational Neuroscience and Clinics 2017年第4期3卷 229-236页

作者： hiroshi Ujiie Chie Shinohara Yoshinori Tamano Kouichi Katou Akira teramoto Department of Neurosurgery Tokyo Rosai Hospital Department of Neurosurgery Blue–sky Matsui Hospital Department of Neurosurgery Narita Tomisato Tokusyukai Hospital Department of Neurosurgery Koshigaya Neurosurgical Clinic

We reviewed basic considerations in fluid dynamics of cerebral aneurysms and applied these in surgery on the three most common types: internal carotid-posterior communicating artery,middle cerebral artery,and anterior communicating artery. It was found that aneurysmal initiation and growth do not occur at symmetric bifurcations. As blood flow always obeys the law of inertia,jet flow into the aneurysm will disperse along the wall; assuming the aneurysmal wall strength is even,the shape of the aneurysm becomes round or oval. When neurosurgeons encounter an aneurysm that is not round or oval,the wall may be fragile and requires great care during surgical manipulation.

关键词： intracranial aneurysm subarachnoid hemorrhage computational fluid dynamics shear stress partial epilepsy middle cerebral artery internal carotid artery anterior cerebral artery

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Low Frequency Ultrasonication Induced Antitumor Effect in 5-Aminolevulinic Acid Treated Malignant Glioma

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Journal of Cancer Therapy 2013年第1期4卷 170-175页

作者： Fumio Yamaguchi Takayuki Asakura hiroshi Takahashi Takayuki Kitamura Akira teramoto Department of Neurosurgery Nippon Medical School Tokyo Japan

We investigated the feasibility of sonodynamic therapy for glioma by low frequency ultrasoundwith5-aminolevulinic acid (5-ALA), a precursor of protoporphyrin IX (PpIX) in heme synthetic process. In vivo tumor model was made by inoculating human glioma cell line U87-MG subcutaneously in nude mice. The tumor was sonicated by 25-kHz ultrasound 4 hours following administration of 5-ALA. The tumor size decreased in 5-ALA administered (ALA(+)US(+)) mice, while increased in non-5-ALA administrated (ALA(-)US(+)) mice and non-sonicated mice (ALA(+)US(-)). The immunohistochemical analysis revealed an apoptotic change in tumor tissue of ALA(+)US(+) mice. The results showed the therapeutic effect of 25 kHz ultrasound for the glioma in 5-ALA administered tumor-bearing mice by inducing apoptotic change of tumor cells. This is a first report to elucidate the feasibility of therapeutic use of 25 kHz, relatively low frequency, ultrasound in sonodynamic therapy using 5-ALA as a sonosensitizer precursor. The utilization of this frequency will contribute to the development of sonodynamic therapy for gliomas and the spread of this technique in many hospitals that possess ultrasonic aspirators.

关键词： Glioma Sonodynamic Therapy 5-Aminolevulinic Acid Protoporphyrin IX Ultrasonication

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Effect of Non-Equilibrium Condensation of Moist Air on Unsteady Behaviour of Shock Waves around a Circular Arc Blade

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Journal of Thermal Science 2007年第2期16卷 134-139页

作者： Shigeru MATSUO Kenbu teramoto Miah MD.Ashraful ALAM Toshiaki SETOGUCHI Heuy Dong KIM Shen YU Department of Mechanical Engineering Saga University1Honjo-machiSaga-shiSaga 840-8502Japan Department of Mechanical Engineering Khulna University of Engineering & TechnologyKhulna-9203Bangladesh School of Mechanical Engineering Andong National University388Songchun-dongAndong 760749Korea Institute of Engineering Thermophysics Chinese Academy of SciencesP.O.Box 2706Beijing 100080China

The unsteady phenomena in the transonic flow around airfoils are observed in the flow field of fan, compressor blades and butterfly valves, and this often causes serious problems such as the aeroacoustic noise, the vibration. In the transonic or supersonic flow where vapour is contained in the main flow, the rapid expansion of the flow may give rise to a non-equilibrium condensation. However, the effect of non-equilibrium condensation on the transonic internal flows around the airfoil has not yet been clarified satisfactorily. In the present study, the effect of non-equilibrium condensation of moist air on the self-excited shock wave oscillation on a circular arc blade was investigated numerically. The results showed that in the case with non-equilibrium condensation, frequencies of the flow oscillation became smaller than those without the non-equilibrium condensation.

关键词： compressible flow transonic flow shock wave oscillation non-equilibrium condensation simulation

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