著者

京谷 好泰

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会誌 (ISSN:24242675)

巻号頁・発行日

vol.91, no.834, pp.485-487, 1988-05-05 (Released:2017-06-21)

著者

中出 孝次 佐久間 豊 梶島 岳夫

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集 (ISSN:21879761)

巻号頁・発行日

vol.87, no.893, pp.20-00366, 2021 (Released:2021-01-25)

参考文献数

11

被引用文献数

1 1

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To clarify the mechanisms underlying airflow-induced vibrations of high-speed trains running through tunnels, large-eddy simulation of a large-scale flow structure around a simplified 6-car train model was conducted. Since actual trains run on one of the double track lines, the position of the train model was made to deviate from the tunnel center and hence the gap between one of the sides of the train and the tunnel wall is narrower than that of the other side. A train running in the open air was also calculated for comparison. The results of this study shed light on the generation mechanism of the pressure fluctuations acting on the side of high-speed trains as follows. Firstly, in the open air, the air velocity in the space between the underbody and the ground gradually decreases from the head toward the tail of the train. Thus, the air velocity is slower than that on both sides of the train, which generates shear flows near the bottom edges of both sides of the train. The shear flows cause large Karman vortex-like vortices (staggered Karman vortex street), which in turn lead to a meandering airflow beneath the underbody of the train. Secondly, in the tunnel, the air velocity not only in the gap between the underbody and the ground but also in the narrower gap between the side of the train and the tunnel wall gradually decreases from the head toward the tail of the train. In the same mechanism as the open air, a meandering airflow is generated throughout the side and underbody of the train and causes pressure fluctuations along the side of the train. Finally, it is demonstrated that the wavelength of pressure fluctuations along the side of the actual train can be estimated from the present LES results.

著者

阿部 裕幸 筒井 康賢 吉識 晴夫

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集 B編 (ISSN:03875016)

巻号頁・発行日

vol.59, no.567, pp.3388-3392, 1993-11-25 (Released:2008-03-28)

参考文献数

9

被引用文献数

1

---

The Agency of Industrial Science and Technology, Ministry of International Trade and Industry has been researching and developing three types of 300kW ceramic gas turbines since 1988. The turbine blade's Reynolds numbers based on the basic design are predicted to be in the region of l04∼105. In the field of wind turbines, for example, some studies on the characteristics of airfoils at low Reynolds numbers have been carried out. However, it is not yet obvious how the turbulence affects the characteristics of airfoils. This paper describes the experimental results obtained with use of turbulence screens. It is found that laminar seperated flows, in some cases, reattaches to airfoils by raising turbulence intensity of free stream at Reynolds numbers of 0.5×105 and 1×105, and that lift to drag ratios increase further.

著者

天沼 大輝 高木 亮

出版者

一般社団法人 日本機械学会

雑誌

交通・物流部門大会講演論文集 2018.27 (ISSN:24243175)

巻号頁・発行日

pp.1034, 2018 (Released:2019-06-25)

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The authors propose the idea of ultra-high-frequency rail network timetabling. In such a timetable, the scheduled trains will take very diverse routes on a given rail network to meet the diverse needs of the passengers and to enable ultra-high-frequency train operation. However, at junctions where two or more lines meet, the level crossing interference between different railway tracks will form the bottleneck for the realisation of such high train frequency. The typical example of this can be seen at crossovers between fast and slow lines on the quadruple track railway paired by use. To reduce such level crossing interference, the authors propose the simultaneous crossovers of two trains in both directions at crossover tracks, and the installation of multiple crossover tracks at one junction for realtime selection of the optimal route. In this paper, the authors present the detailed calculation of headways between trains at this kind of crossover tracks, which will form the basis of the authors’ future research into their ideas.

著者

佐藤 優也 原田 研介 酒田 信親 万 偉偉 ラミレス イクシェル

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集 (ISSN:21879761)

巻号頁・発行日

vol.84, no.861, pp.17-00546-17-00546, 2018 (Released:2018-05-25)

参考文献数

19

被引用文献数

1

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In this paper, we propose a novel two-stage approach on picking an object from randomly stacked pile. We especially consider a situation where it is difficult for a 3D depth sensor to identify the pose of objects such as shinny ones and black ones. For such objects, our method first roughly grasps some of the objects from the pile without using the visual information and roughly place them onto a working table. After some of the objects are placed on a working table, a robot picks one of them by detecting the 2D position of objects placed on a working table by using the 2D RGB image. We performed experiments for several objects with different shape and weight. Through experimental study, we confirmed that a robot can identify the position of one of the objects after the objects are placed on a working table and that one of the objects can be successfully picked up by a robot.

著者

野田 伸一 石橋 文徳 井手 勝記

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集 C編 (ISSN:03875024)

巻号頁・発行日

vol.59, no.562, pp.1650-1656, 1993-06-25 (Released:2008-02-26)

参考文献数

9

被引用文献数

9 7

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The induction motor is used in many industries. These days motor noise reduction is often required due to environmental concerns. This paper is concerned with the reduction of motor noise. The relationship of exciting force and vibration mode of the stator core is analyzed. An exciting force as an electromagnetic radial force was applied to the stator core. Analysis was performed for the case of a continuous distributed force and the case of a discrete multipoint exciting force. The vibration behavior of the core was analyzed theoretically, numerically (FEM) and experimentally with respect to modes, frequency and phase of exciting force. It has been confirmed that : 1. in the continuous distributed excitation, the core vibrates when M=±N and the exciting frequency coincides with the natural frequency, 2. in the discreted multipoint excitation, the core vibrates when M±N=mK. Here, N is the natural frequency mode, "is the excitation frequency mode, m is an integer, and K is the number of applied points of the exciting force.

著者

鈴木 栄司

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集 (ISSN:21879761)

巻号頁・発行日

pp.21-00336, (Released:2022-06-23)

参考文献数

7

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Jitter Ring is the popular toy which has another name called as “Chatter Ring” or “Gyro Ring”. This toy is composed of a circular ring and the washer inserted into the ring. Just after supplying the washer with an initial angular velocity, the player of this toy has only need to wheel the ring in the vertical state by handling each hand alternately. Then, the washer will continue to rotate with fluctuation by this operation. Further the player will feel the oscillating response through the driving hands. This rotatory motion of the washer is somewhat complicated and the analyses tried up to now concerning this motion don’t almost appear in public. Consequently the author thought that there were the significant meanings in the dynamic analysis for this motion of the washer. Considering the friction between the ring and the washer, he performed the three-dimensional analysis by regarding the washer as the rigid body without a fixed point and adopting Eulerian angles in this research. As a result, the actual behavior with fluctuating rotation of the washer was confirmed by the numerical analysis. Furthermore, he investigated the influence on the motion of the washer by varying each value of parameters in this system.

著者

山下 英男

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会誌 (ISSN:24242675)

巻号頁・発行日

vol.59, no.444, pp.42-46, 1956-01-05 (Released:2017-06-21)

著者

赤塚 純一 永井 伸治 本阿弥 眞治

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集B編 (ISSN:18848346)

巻号頁・発行日

vol.77, no.784, pp.2391-2400, 2011 (Released:2011-12-25)

参考文献数

18

被引用文献数

3 5

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This paper propose two new flow visualization methods based on the Background-Oriented Schlieren (BOS) technique for compressible flow. One is “Simplified background-oriented schlieren (S-BOS) ”. This technique does not require a cross-correlation algorithm, which is typically used in BOS. The data processing is much simpler than that of the original BOS, since image displacement associated with density gradient is algebraically calculated from intensities of the images with the periodic background pattern. Moreover, it easily allows us to automate the data processing, because it is neither necessary to remove incorrect vectors nor to optimize parameters such as the interrogation window and search window. The other is referred to “Wavelet-based background-oriented schlieren (W-BOS)”. This technique provides a schlieren image using continuous wavelet transformation for the periodic background pattern. By transforming the periodic intensity pattern into the phase, a schlieren image can be obtained easily. Since the optical setup in both techniques is simpler than that of a conventional schlieren imaging, they could be used in various situations including field tests. A wind tunnel test was conducted in a 1 m × 1 m supersonic wind tunnel. Their usefulness was demonstrated by comparing with the conventional schlieren images.

著者

迫畑 武司

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会誌 (ISSN:24242675)

巻号頁・発行日

vol.116, no.1141, pp.838-839, 2013-12-05 (Released:2017-06-21)

著者

山田 泰之 風間 祐人

出版者

一般社団法人 日本機械学会

雑誌

ロボティクス・メカトロニクス講演会講演概要集 2021 (ISSN:24243124)

巻号頁・発行日

pp.2A1-D08, 2021 (Released:2021-12-25)

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During overhead work, workers need to keep raising up upper limb weights. In that working posture, it is necessary to keep the arm with its own weight of approximately 2 to 4 kg. It is considered to be a cause of fatigue of arms and back. Therefore, in this research, we attempted to reduce the fatigue of the upward work by the weight compensation mechanism that balances the elastic force of the spring and their arms weight. It can compensate for their arms weight by the force of the spring in various postures of the arm at the time of work by using lightweight and highly accurate weight compensation mechanism authors developed. Furthermore, a horizontal multi-linkage mechanism that follows the movement of the shoulder and arm of a human is used. In this way, it is completely pure mechanical and simple structure without a motor and battery, and it can be expected effective in all upward works. The mechanism of self-weight compensation and the degree of freedom and parameters of the link mechanism were studied. For practical use, we discussed how to achieve both a simple structure, work movement followability, and mass productivity.

著者

川渕 一郎

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会誌 (ISSN:24242675)

巻号頁・発行日

vol.113, no.1096, pp.154-155, 2010-03-05 (Released:2017-06-21)

著者

重藤 文彬 松岡 美樹 高島 俊

出版者

一般社団法人 日本機械学会

雑誌

ロボティクス・メカトロニクス講演会講演概要集 2013 (ISSN:24243124)

巻号頁・発行日

pp._2P1-Q08_1-_2P1-Q08_4, 2013-05-22 (Released:2017-06-19)

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As one field of sports, there is a game of bike trial. Riders operate mountain bicycles with various advanced techniques. The purpose of this research is to create a bike trial robot that can operate a mountain bicycle and perform various maneuvers such as jumping, bike wheelie and etc. In this paper, a mechanical analysis concerning individual techniques including bike wheelie and Daniel is presented. The analyzing method and the results of computer simulations are also presented.

著者

金子 友暁 横山 博史 佐藤 充 西川原 理仁 柳田 秀記

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集 (ISSN:21879761)

巻号頁・発行日

pp.22-00044, (Released:2022-05-25)

参考文献数

16

---

For a small axial fan in a duct, the effects of acoustic resonance occurring in the duct on the flow around the fan are focused on. To clarify the condition for the intense acoustic resonance, the effects of the rotational speed and duct width on the flow and acoustic fields around the fan were investigated by compressible flow simulations with a volume penalization method. The computational methods were validated by comparing the predicted static pressure rise and aerodynamic sound by the fan with those measured. The sound pressure level became most intense for a specific rotational speed, where the acoustic resonance occurs at the blade passing frequency in the upstream duct. Although the overall tendency of the increase in the static pressure coefficient was found for a higher rotational speed with the thinner momentum thickness around the blade surface, the static pressure coefficient drops at the rotational speed for the acoustic resonance. Moreover, the acoustic resonance became more intense for a narrower duct width. In this condition, flow disturbances occur near the wall of the bell-mouthed inlet of upstream duct due to the acoustic resonance, which prompts the inflow turbulence to the fan. To clarify the effects of the acoustic resonance on the flow around the fan, the computation with the artificially suppressed acoustic resonance was also performed and the predicted flow fields were compared with those with intense acoustic resonance for the same rotational speed and duct width. The incoming flow to the fan is confirmed to become more turbulent when the acoustic resonance occurs, which promotes the spreading of the tip vortices between rotor blades. As a result, the blade loading decreases and the turbulence in the blade wake leading to mixing loss becomes intense, causing the static pressure rise by the fan to decrease.

著者

田原 誠 野波 健蔵

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集C編 (ISSN:18848354)

巻号頁・発行日

vol.78, no.787, pp.872-882, 2012 (Released:2012-03-25)

参考文献数

18

被引用文献数

1 3

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Recently, Quad-rotor type helicopters which are representative of Multi-rotor type helicopters have been extensively developed over the world. The Multi-rotors are expected to replace Single-rotor type helicopters as an industrial helicopter because of their simplicity of the structure and good maintainability. In this paper, we focused on the operation problems of previous industrial helicopters and applied the Multi-rotors by a generalized design method. The generalization of the design method is performed considering variation of requirements of airframe specifications. In addition, we considered using commercial components rather than customized components in each process, so we achieved cost reduction compared with previous study. At first, we introduce the required specifications of a small pesticide application in this study and present the airframe design method. And then, we tuned parameters with presented simulation model and implement a multi-rotor type helicopter following the design method. Finally, we show the flight result and present the effectiveness of the design method.

著者

藤井 文夫 Kuo Mo HSIAO 小林 卓哉 井上 吉弘 新田 高洋

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集 (ISSN:21879761)

巻号頁・発行日

vol.82, no.836, pp.15-00623, 2016 (Released:2016-04-25)

参考文献数

9

被引用文献数

1

---

The popular sports entertainment, billiards, is rich in mechanical issues such as 3D finite rotation, collision, contact and friction, evoking a research interest in rigid-body dynamics, nonlinear CAE and computational mechanics. However, the 3D nonlinear behavior of a rigid ball has so far hardly received the attention of scholars to exercise the mechanical modeling skill. The represent study focuses, therefore, on 3D nonlinear billiard dynamics and attempts to precisely predict the ball behavior in finite rotational motion with collision, contact and slip friction. In dependence upon ball situations, 4 different models are proposed. They are namely, rotation model, strike model, collision model and reflection mode. The rotation model is an elementary model and describes the 3D ball motion after a cue strike and subject to table friction only. The strike model is useful to study the effects of cue striking. For simplicity, the strike points are limited to the ball center, 12, 3, 6 and 9 o'clock' in the ball projection. The collision model ignores the ball-to-ball friction and the law of conservation of momentum holds to predict the velocities of two balls after collision. The reflection model simulates the ball-to-cushion contact in bank shots. Incidence angle, translational and rotational velocities, cushion elasticity and frictional properties may be variable in a parameter study. In all these 4 models, the ball is assumed to be in contact to the table surface. Masse or jump shots are excluded in modeling. The equations of ball motion are time-integrated by forward Euler method. The models are verified and validated in numerical examples including optimization and parameter studies. All computed results well agree with the hustler’s experiences in game practice. The present research work will contribute to develop a skill-up program of professional hustlers.

著者

松下 和磨 森本 雄矢 竹内 昌治

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集 (ISSN:21879761)

巻号頁・発行日

vol.86, no.890, pp.20-00180, 2020 (Released:2020-10-25)

参考文献数

13

被引用文献数

1 5

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Biohybrid robots composed of synthetic skeletons and living components have recently gained interests as a solution to engineering biological dynamic systems. Among the living components, muscle tissues are used as actuators for biohybrid robots, resulting in vitro reproduction of various movements. Especially, swimming robots containing living muscle tissues or cardiomyocytes have been proposed as representative examples of biohybrid robots. However, these robots have limitations on reproducibility and controllability due to individual differences between each explanted living muscle tissues and the self-contraction of cardiomyocytes, respectively. To solve the issue, a swimming robot with cultured skeletal muscle tissue is required since it allows to control the shape and contraction of the cultured tissue. In this paper, we propose the construction method of a swimming robot with cultured skeletal muscle tissue. Our method can prevent spontaneous shrinkage before transferring the tissue from an appropriate culture substrate for tissue formation to the swimming robot. Using the method, we succeeded in the preparation of a swimming robot with three different robot skeleton and skeletal muscle tissues cultured under the same condition, regardless of the spontaneous shrinkage during culture. As a result, we obtained the relationship between shapes of robot skeletons and propulsion of the robot and confirmed that the robot can move forward by shaking a tail fin. We believe that the method for integrating skeletal muscle tissues with the synthetic skeleton will be useful for the easy preparation of biohybrid robots and devices.

著者

小林 義行

出版者

一般社団法人 日本機械学会

雑誌

スターリングサイクルシンポジウム講演論文集 2001.5 (ISSN:24242926)

巻号頁・発行日

pp.73-74, 2001-10-25 (Released:2017-06-19)

著者

田中 泰爾 大石 義彦 朴 炫珍 田坂 裕司 村井 祐一 川北 千春

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集 (ISSN:21879761)

巻号頁・発行日

vol.88, no.907, pp.21-00297, 2022 (Released:2022-03-25)

参考文献数

24

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Drag reduction by bubble injection in turbulent boundary layers was investigated using a 36-m-long flat-bottom model ship. The model ship was towed at 8.0 m/s, resulting in a downstream-distance-based Reynolds number as high as 2.9 × 108. The total resistance exerting on the model ship was reduced, and the resistance reduction increased with the air flow rate for the bubble injection. The local wall shear stress on the bottom plate was measured at multiple locations to clarify the streamwise transition of the drag reduction. The local drag reduction observed at the upstream measurement locations was increased with the air flow rate. The higher gas flow rate, moreover, produced the longer streamwise persistence of the drag-reduction effect. These multiple factors improved the efficiency of the total resistance reduction against the power consumption for the bubble injection. We provide the estimation of total frictional drag reduction for the full-scale ships using the equation of the local friction coefficient obtained experimentally. The results of the model ship experiment and the full-scale estimation consistently indicated that the downstream persistence of the local drag-reduction effect strongly affect the total drag reduction of such the long hulls.

著者

古川 亮 増西 桂 古賀 章浩 川島 浩幸 小林 亮夫 籾内 正幸

出版者

一般社団法人 日本機械学会

雑誌

年次大会講演論文集

巻号頁・発行日

vol.2007, pp.317-318, 2007

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For high-resolution retinal camera, we have developed an adaptive optics system using a membrane deformable mirror (DM) with electrostatic actuators. An aberration compensation algorithm is adopted in the system, which can generate appropriate control input by a linear combination of voltage templates prepared in advance, each of that forms a specific Zernike shape approximately. The nonlinear effect and strong coupling of control channels in continuous-surface DM make it difficult to form the desired mirror surface shapes. In this paper, we propose a computational method to obtain the voltage templates using genetic algorithm and grouping electrodes for reducing the number of independent voltage sources. The results show that the method can be used to obtain appropriate applied voltages for high-order Zernike shapes.