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Flow Induced Acoustic Resonance in In-line Tube Banks

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Journal of Thermal Science 2006年第3期15卷 226-232页

作者： Hiromitsu Hamakawa Tohru Fukano eiichi nishida YoshikazuS atou Department of Mechanical Engineering Oita University 700 Dannoharu Oita 870-1192 Japan Department of Environmental Symbiosis Engineering Kurume Institute of TechnologyKamitsu-machi 2228 Kurume 830-0052 Japan Department of Mechanical Engineering Shonan Institute of Technology Tujido Nishi Kaigan1-1-25 Fujisawa 251-8511 Japan Honda Motor Co. Ltd. Japan

In the present paper the attention is focused on the relation between vortex shedding phenomena and acoustic resonance which occurred in the two-dimensional model of boiler. There were tube banks with in-line arrangement for small tube pitch ratio. We measured the sound pressure level, the phase delay of acoustic pressures, the spectrum of velocity fluctuation and the gap velocity. As a result, we found two peak frequencies of sound pressure level with different Strouhal numbers St, mainly about 0.26 and 0,52, The noise of St=0.26 was the resonance of transverse mode and St=0.52 was longitudinal mode. The vortex shedding of St=0.15 was generated inside the tube banks without acoustic resonance. As gap velocity increased, we observed that the peak level of spectrum was weak and broad-banded, The onset velocity of the acoustic resonance of longitudinal mode was lower than that of transverse mode.

关键词： acoustic resonance flow induced vibration vortex in-line tube banks

Prediction of Acoustic Absorption Performance of a Perforated Plate with Air Jets

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Journal of Thermal Science 2017年第4期26卷 378-384页

作者： Hiromitsu Hamakawa Masanori Miyazaki Yuta Asai Eru Kurihara eiichi nishida Hidechito Hayashi Department of Mechanical Engineering Oita University700 DannoharuOita 870-1192Japan Graduate Student Oita University700 DannoharuOita 870-1192Japan Department of Mechanical Systems Engineering Shonan Institute of Technology1-1-25 Tsujido-NishikaiganFuji-sawaKanagawa 251-8511Japan Department of Mechanical Engineering Nagasaki University1-14 Bunkyo machiNagasaki852-8521Japan

The present study focuses on the prediction of acoustic absorption performance of a perforated plate with air jets by theoretical calculations. In addition, we experimentally measured the flow rate, internal pressure, acoustic pressure, and transfer function using an acoustic impedance tube. The normal incidence absorption coefficient was calculated from the measured transfer function using transfer function methods. We investigated the influences of background air space, flow velocity, thickness, aperture rate, and aperture diameter of a perforated plate on the acoustic absorption characteristics. The frequency characteristics of the acoustic absorption coefficient showed a maximum value at a local frequency. As the background air space increased, the peak frequency of acoustic absorption characteristics decreased. As the flow velocity passing through the apertures increased, the peak level of the acoustic absorption coefficient also increased. The theoretical results agreed well with the experimental ones qualitatively.

关键词： acoustic absorption perforated plate theoretical prediction acoustic impedance tube air jets

Effect of Arrangement of Tube Banks on Acoustic Resonance

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Open Journal of Fluid Dynamics 2012年第4期2卷 311-317页

作者： Hiromitsu Hamakawa Tatsuaki Nakamura Kenta Asakura eiichi nishida Eru Kurihara Department of Mechanical Engineering Oita University Oita Japan Postgraduate Course Oita University Oita Japan Shonan Institute of Technology Fujisawa Japan

In the present paper the attention is focused on effect of arrangement of tube banks on acoustic resonance which occurred in the two-dimensional model of boiler. We have examined the characteristics of vortex shedding and acoustic resonance generated from in-line and staggered tube banks. At the small tube pitch ratio in in-line tube banks, acoustic resonance of third and fourth mode in the transverse direction occurred. As the tube pitch ratio in the flow direction decreased, the vortex shedding frequency became broad-band. The alternative vortex shed from in-line tube banks. The multiple resonance modes were generated within the broad-band vortex shedding frequency. And the acoustic resonances of lower-order modes occurred at the higher gap velocity. On the other hand, at the small tube pitch ratio in staggered tube banks, acoustic resonance did not occurred, although the vortex shed at the resonance frequency in tube banks. The pressure drop at staggered tube banks was larger than that of in-line tube banks. The symmetric vortices were observed inside staggered tube banks at the small tube pitch ratio.

关键词： Acoustic Resonance Vortex Tube Banks In-line Arrangement Staggered Arrangement Boiler

Acoustic Absorption Characteristics of Perforated Thin Plate with Air Jets and Cavity

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Open Journal of Fluid Dynamics 2015年第1期5卷 1-9页

作者： Hiromitsu Hamakawa Hiroki Matsuoka Taiki Yamai Kenta Asakura Toru Otsuru Reiji Tomiku Eru Kurihara Hidechito Hayashi eiichi nishida Department of Mechanical Engineering Oita University Oita Japan Graduate School Master’s Program of Engineering Oita University Oita Japan Torishima Pump Mfg. Co. Ltd Takatsuki-shi Osaka Japan Department of Architecture Oita University Oita Japan Department of Mechanical Engineering Nagasaki University Nagasaki Japan Department of Mechanical Systems Engineering Shonan Institute of Technology Fujisawa-shi Kanagawa Japan

The present paper focuses on the effect of air jets through a perforated thin plate on the characteristics of an acoustic absorption coefficient. We measured the flow rate, internal pressure, acoustic pressure, and transfer function by using an improved acoustic impedance tube. The normal incidence absorption coefficient was calculated from the measured transfer function using transfer function methods. As a result, the frequency characteristics of the acoustic absorption coefficient against the frequency showed a maximum value at the local frequency. The peak frequency of the acoustic absorption coefficient depended on the thickness of the background air space and the thickness of the perforated plate. As the flow rate increased through the micropores, the peak level of the acoustic absorption coefficient also increased until a flow rate of 80?l /min. As the flow rate further increased, the peak level of the acoustic absorption coefficient decreased and that of the high frequency band increased.

关键词： Acoustic Absorption Coefficient Perforated Plate Cavity Micropores Air Jets Acoustic Impedance Tube

Moisture Detection of SF_6 Gas Instruments by Solid Electrolyte

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稀有金属材料与工程 2006年第A3期35卷 353-356页

作者： eiichi Nagao Tadao Minagawa Chieko nishida Mitsuhito Kamei Mitsubishi Electric Corporation 8-1-1Tsukaguchi-HonmachiAmagasakiHyogo661-8661Japan

Humidity measurement in a very low moisture atmosphere was studied by using solid electrolyte film coated with porous electrodes,considering its application to the moisture monitoring of SF_6 gas-insulated high voltage instruments such as gas-insulated switchgear (GIS) and gas circuit breakers (GCBs).Compared to the AC impedance values measured in an ambient atmosphere where the moisture atmosphere is far higher than that in these instruments,considerably large impedance values were obtained in a very low moisture *** impedance was systematically measured in accordance with the conditions of these instruments whose moisture contents were less than 1 000×10^(-6).A good correlation was obtained between the impedance values and the moisture *** frequency characteristics of the impedance were analyzed based on a conventional equivalent circuit where a number of CR circuits were connected in *** the dielectric relaxation of each circuit,it was found that the frequency characteristics of the impedance can be explained by the equivalent circuit. Two semicircles were clearly obtained in the Cole-Cole impedance plot which are thought to reflect the impedance characteristics of the film and the *** AC impedance can be a good indicator of the moisture content of SF_6 gas-insulated high voltage instruments.

关键词： humidity moisture solid electrolyte impedance ion conductivity

What is artificial endocrine pancreas? Mechanism and history

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World Journal of Gastroenterology 2009年第33期15卷 4105-4110页

作者： Kenro nishida Seiya Shimoda Kenshi Ichinose eiichi Araki Motoaki Shichiri Division of Diabetes and Endocrinology Minamata City Hospital and Medical Center Department of Metabolic Medicine Graduate School of Medical SciencesKumamoto University

The artificial endocrine pancreas is a feedback control instrument that regulates insulin delivery on a minute-by-minute basis according to measured blood glucose levels. Only one type of bedsidetype artificial endocrine pancreas is now available in Japan: STG-22 (Nikkiso Co. Ltd., Japan). In the insulin infusion algorithm, insulin is infused on the basis ofits proportional and derivative actions, to blood glucose concentrations with a constant time delay. The bedside-type artificial endocrine pancreas has been proven to be useful not only as a therapeutic tool for diabetes mellitus, but also as an elegant research tool for investigating the pathophysiology of the disease, by using the euglycemic hyperinsulinemic glucose clamp technique. The wearable type of closed-loop system has been developed recently. The breakthrough is the establishment of a needle-type glucose sensor. The development of closed-loop glycemic control systems that enable long-term physiological regulation has focused on implantable devices. Much effort has been expended to realize these devices.

关键词： Diabetes mellitus Artificial pancreas Blood glucose Insulin Infusion

Esophageal early basaloid squamous carcinoma with unusual narrowband imaging magnified endoscopy findings

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World Journal of Gastroenterology 2014年第35期20卷 12673-12677页

作者： Yugo Kai Motohiko Kato Yoshito Hayashi Tomofumi Akasaka Shinichiro Shinzaki Tsutomu nishida Masahiko Tsujii eiichi Morii Tetsuo Takehara Department of Gastroenterology and Hepatology Osaka University Graduate School of Medicine Department of Diagnostic Pathology Osaka University Hospital

Basaloid squamous carcinoma (BSC) is a rare variant of esophageal cancer. There are very few reports of “early” BSC. Here we report a case of early BSC with unusual findings by narrowband imaging magnified endoscopy (NBI-ME). A 70-year-old man with a middle thoracic esophageal tumor was referred to our hospital. White-light endoscopy revealed a reddish depressed lesion 5 mm in diameter having a subepithelial tumor-like prominence with a gentle rising slope. NBI-ME revealed irregular loop-shaped microvessels coexistent with thick irregularly branched non-looped vessels. Iodine staining revealed a pale brown lesion. We performed endoscopic submucosal dissection for diagnostic treatment. Histologic examination showed the proliferation of basal cell-like hyperchromatic tumor cells in the lamina propria and with slight invasion into the submucosa at a depth of 320 μm. The tumor cells formed solid nests and microcystic structures, containing an Alcian blue-positive mucoid matrix. The surface was covered with squamous epithelium without cellular atypia. Thin vessels were observed in the intra-epithelial papilla and thick vessels were observed around the solid nests beneath the epithelium. Based on these findings together, we diagnosed the lesion as BSC. In this case, the NBI-ME findings differed from those of typical squamous cell carcinoma in that both non-invasive cancer-like irregular loop-shaped microvessels coexisted with massively invasive cancer-like thick non-looped vessels. We speculate that the looped and non-looped vessels observed by NBI-ME histologically corresponded to thin vessels in the intra-epithelial papilla and thick vessels around the tumor nests, respectively. These NBI-ME findings might be a feature of early esophageal BSC.

关键词： Basaloid squamous carcinoma Narrowband imaging Esophagus Endoscopic submucosal dissection