著者

酒井 忍 尾田 十八 米村 茂 坂本 二郎

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 A編 (ISSN:03875008)

巻号頁・発行日

vol.73, no.734, pp.1177-1182, 2007-10-25 (Released:2011-03-02)

参考文献数

10

被引用文献数

2 1

---

In the United States and Japan, baseball is a very popular sport played by many people. However, the ball used is hard and moves fast. A professional baseball pitcher in good form can throw a ball at up to 41.7 m/s (150km/hr). If a ball at this speed hits the batter, serious injury is quite likely. In this paper we will describe our investigations on the impact of a baseball with living tissues by finite element analysis. Baseballs were projected at a load cell plate using a specialized pitching machine. The dynamic properties of the baseball were determined by comparing the wall-ball collision experimentally measuring the time history of the force and the displacement using dynamic finite element analysis software (ANSYS/LS-DYNA). The finite element model representing a human humerus and its surrounding tissue was simulated for balls pitched at variable speeds and pitch types (knuckle and fast ball). In so doing, the stress distribution and stress wave in the bone and soft tissue were obtained. From the results, the peak stress of the bone nearly yielded to the stress caused by a high fast ball. If the collision position or direction is moved from the center of the upper arm, it is assumed that the stress exuded on the humerus will be reduced. Some methods to reduce the severity of injury which can be applied in actual baseball games are also discussed.

著者

寺地 淳 津田 剛 野田 徹 久保 賢明 伊東 輝行

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.71, no.710, pp.2581-2587, 2005-10-25 (Released:2011-08-16)

参考文献数

13

被引用文献数

1

---

Combustion in IC engines involves very complicated phenomena, which are strongly affected by engine speed, load and turbulence intensity. The aim of this study was to develop a flame propagation model and a knock prediction technique applicable to various engine oparating conditions. A new flame propagation model (UCFM) has been developed that improves the Coherent Flamelet Model (CFM) by considering flame growth both in terms of the turbulent flame kernel and laminar flame kernel. A knock prediction model was developed by implementing the Livengood-Wu integral as the autoignition model in the flame propagation model. The combined model allows evaluation of both where and when autoignition occurs in a real shape combustion chamber. The three-dimensional calculation results indicate the general tendency for the pressure history and the location where autoignition occurs in the combustion chamber.

著者

吉田 正武

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.64, no.617, pp.305-311, 1998-01-25 (Released:2008-03-28)

参考文献数

8

被引用文献数

1

---

The author had previously reported that work done by a power stroke of 4-stroke gasoline engine is expressed as a function of engine factors (ignition timing, combustion period, heat release diagram and so on.) using an approximate pressure diagram of a cylinder, which is an approximate solution of the energy conservation equation. In this report, the author examined the effects of combustion period and heat release diagram on the work done by a power stroke. The results show that (1) the factors mentioned above have little effect on the thermal efficiency at the optimum ignition timing (MBT) ; (2) When combustion period is decreased, MBT shifts from advanced crank angle to retard crank angle in proportion to the decrease of combustion period ; and (3) The idea that a short combustion period improves thermal efficiency does not apply in the case of non-adiabatic engines.

著者

朝岡 洸太 和久田 康平 金本 凌 諏訪 秀樹 荒木 拓人

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.22-00325, (Released:2023-03-02)

参考文献数

24

---

Various fields, such as the paper industry, chemical engineering, and renewable energy, are faced with gas-liquid two-phase flows and are being studied by visualization and observation. Although it is necessary to quantitatively evaluate the characteristics of bubbles, there is a limitation in the amount of labor required for detection and measurement by human observation of images. There are no examples for bubbles in polymer electrolyte membrane water electrolysis (PEMWE), where the bubbles in PEMWE have heterogeneous backgrounds, unpatterned patterns, and unclear bubble contours. Existing methods for detecting these bubbles are not expected to be accurate enough. In this study, a deep learning-based bubble detection method using convolutional neural networks (CNN) was developed for bubbles in PEMWE. Our method has two novel approaches: first, we developed an algorithm that automatically draws a pseudo-bubble image based on an actual bubble image on an arbitrary background as a method for automatically generating training data for the CNNs. Second, we developed a CNN-based bubble detection method that uses the motion of bubbles, specifically, the difference between the bubble image and the image from one frame ago, as input. Finally, we tested the algorithm on bubble images in a PEMWE and achieved an F1 score of 0.83 or better for all current densities of 0.5, 1, 2, and 3 A/cm2, and an F1 score of 0.844 for the entire detection.

著者

平野 敏右

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.74, no.634, pp.1410-1417, 1971 (Released:2017-06-21)

被引用文献数

1

著者

高木 健 山崎 透 石井 抱

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 2011 (ISSN:24243124)

巻号頁・発行日

pp._1A1-J04_1-_1A1-J04_4, 2011-05-26 (Released:2017-06-19)

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This paper describes an oblique feed screw which can be used as load-sensitive continuously variable transmission (CVT). This CVT consists of a screw, spring, and bearing, and is remarkably simple and compact. Its reduction ratio change automatically in response to the load. We have developed the CVT of 13.8 [g]. We have experimentally verified that it can exert a very strong force of more than 100 [N], and the CVT can increase its reduction ratio form 20 to 45.

著者

小島 晋爾 勝見 則和 宮川 浩 奥村 猛 植田 貴宣

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.65, no.638, pp.3523-3529, 1999-10-25 (Released:2008-03-28)

参考文献数

9

被引用文献数

2 1

---

The slant-shaped squish chamber recently developed by our company improves charging efficiency and raises compression ratio of its gasoline-engines. We clarified its knock suppression mechanism using rapid compression-and-expansion machine, autoignition simulation, and 3-dimensional turbulent flame propagation simulation. The results indicate the following: 1. Timing of flame acceleration is a key of knock suppression, that is, optimum timing of flame acceleration exists in the latter half of combustion, because expansion stroke suppresses the temperature rise in the end gas. This universal mechanism improves knock-limited ignition timing and compression ratio of the above engines. 2. A cause of the flame acceleration in the slant-shaped squish chamber is strengthened turbulence occurring in front of the flame and in reverse squish flow which separates at the squish lip. 3. The reverse squish flow, which is well known to be induced by the suction due to the larger expansion ratio of squish region than the other region of combustion chamber, is enhanced by the thermal expansion of burning mixture.

著者

横田 真斗 久富 彩音 石井 裕 渡辺 富夫

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

pp.22-00228, (Released:2023-02-22)

参考文献数

25

---

Focusing on the correlation between speech sounds and body movements, we developed a voice-driven embodied entrainment character called InterActor that automatically generates communicative motions from speech, and demonstrated the effectiveness of the system. We also developed a communication agent that responds appropriately to utterance contents by focusing on words in speech using speech recognition. However, these systems simply generate body motions from the burst-pause of speech. The response actions corresponding to speaker’s speech speeds were not considered. In this paper, we analyze the relationship between an individual’s speech activity and speech speed[mora/s] from various speech experiments with the aim of facilitating speech according to speaker’s speech characteristics. We develop a voice-driven embodied entrainment system which performs nodding with different speeds according to speech speeds based on speech recognition. Based on the results of the speech experiments, we conduct an online evaluation experiment using videos of multiple speakers with different speaking speeds using the robot as a platform to verify the effectiveness of the response actions generated by the system.

著者

高田 洋吾 荒木 良介 野々垣 元博 海老田 一章 石井 利長 脇坂 知行

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.76, no.764, pp.650-659, 2010-04-25 (Released:2017-06-09)

参考文献数

20

被引用文献数

3 2

---

Polymer electrolyte fuel cell (PEFC) is expected to applications for various usages such as a power source for small robots and personal computers because PEFC has high energy density and can generate electric power under low temperature environment. As the application, swimming fish robots with PEFC are useful for various usages such as ecological investigation in water etc. In the case that rechargeable batteries are used for supplying electricity to robots, they are not able to continue swimming for a long time because of low energy density of the batteries. Therefore, a small and ultra-light passive-type polymer electrolyte fuel cell called "Power Tube" has been developed. On the basis of this fuel cell technology, the authors have created low energy consumption small fish robots powered by Power Tubes on a float or a buoy. The fish robot with a float swims for approximately 50 minutes by only Power Tubes with a voltage booster and the other fish robot with a submersible system can also swim for about 50 minutes by a hybrid system of a lithium polymer battery and Power Tubes.

著者

安田 恵一郎 永岡 右明

出版者

一般社団法人 日本機械学会

雑誌

設計工学・システム部門講演会講演論文集 2003.13 (ISSN:24243078)

巻号頁・発行日

pp.128-129, 2003-10-30 (Released:2017-06-19)

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Recent years, several multipoint-search-based meta-heuristics such as Genetic Algorithm (GA), Particle Swarm Optimization (PSO) have been proposed and have been proved to be efficient methods for global optimization problems. In this report, a new multipoint-search method, which is based on the interaction among search points is proposed. Some simulations using typical knapsack problems verify the search performance of the proposed method.

著者

川副 嘉彦 伊倉 良明

出版者

一般社団法人 日本機械学会

雑誌

ジョイント・シンポジウム講演論文集:スポーツ工学シンポジウム:シンポジウム:ヒューマン・ダイナミックス 2008 (ISSN:24331309)

巻号頁・発行日

pp.165-170, 2008-11-05 (Released:2017-08-01)

被引用文献数

2 2

---

In the previous paper, we realized the simple self-sustained humanlike robust walking & running NANBA of humanoid biped robot GENBE based on distributed control of physical body in a martial art utilizing instability without ZMP (Zero Moment Point) control, which uses only small active power with simple chaotic limit cycle utilizing instability, further developing into autonomous walking, running, instantaneous turn and the simple autonomous shock avoidance during falling down and instantaneous rising up. Instability makes the natural movement. This paper made clear experimentally by using high-speed video camera the mechanism of robustness of humanoid biped robot GENBE who walks and runs everywhere even on the ice and snow.

著者

森西 洋平

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.62, no.604, pp.4106-4112, 1996-12-25 (Released:2008-03-28)

参考文献数

14

被引用文献数

4 5

---

In this report, numerical tests of the conservation properties of finite difference schemes are performed. Inviscid flow simulations in a two-dimensional periodic domain are performed using several finite difference schemes that are discussed in the first and second reports. The momentum and kinetic energy are conserved when the proper schemes in regular and staggered grid systems are used. The defect of the finite difference schemes in a collocated grid system is emphasized in the simulation. In addition, plane channel flows at Re=180 and 2000 are simulated using the proper fourth-order accurate finite difference scheme in a staggered grid system and the results are better than those of the second-order accurate algorithm and an existing fourth-order accurate scheme.

著者

斎藤 諒 三浦 純

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.1P2-G03, 2021 (Released:2021-12-25)

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Recently, many public facilities have been promoted to be barrier-free. In such a situation, an accessibility map that indicates areas that are drivable and areas that are not drivable, such as steps and slopes is very effective for wheelchairs and strollers. This research focuses on viewpoint planning for autonomous 3D measurement by a mobile robot in order to create an accessibility map. For efficient 3D measurements, the viewpoint planning should be done to reduce the size of unknown regions. We plan viewpoints based on the frontier, which is the boundary between the known and the unknown regions. We verify the effectiveness of the proposed method in simulation and by a real robot environment.

著者

鈴木 大介 三村 泰成 廣井 美和

出版者

一般社団法人 日本機械学会

雑誌

シンポジウム: スポーツ・アンド・ヒューマン・ダイナミクス講演論文集 2015 (ISSN:24329509)

巻号頁・発行日

pp._B-32-1_-_B-32-9_, 2015-10-30 (Released:2017-06-19)

被引用文献数

1

---

In recent years, in research fields such as gait analysis, ergonomics and sport, video processing has been used. A high speed camera can observe a motion slowly. We can get an animation of a slow motion by taking a number of frames at the time of photography. A motion capture is also a technique to record the movement of a real person and object digitally. We visualize a movement of the kendo, and analysis a motion of the lower limbs during swing of an experiencer or a beginner. The measurement contents are velocity measurement of the tip of the shinai. Motion analysis of lower limbs and analysis of tendon motion by floor reaction force. There was difference in velocity of the tip of the shinai by a person with experience and an inexperienced person. In the motion analysis on lower limbs, it has been understood that power to step is five times larger than power to kick.

著者

甲藤 好郎 西村 肇

出版者

一般社団法人 日本機械学会

雑誌

日本機械学會論文集 (ISSN:00290270)

巻号頁・発行日

vol.26, no.165, pp.715-719, 1960-05-25 (Released:2008-03-28)

参考文献数

7

被引用文献数

2 2

---

Although heat conduction with phase change has a great field to be solved for its application not only to the study of various natural phenomena, but also to the practices, it seems that the study has not yet been sufficiently developed for the above mentioned purposes because of its difficulties. The authors, therefore, have tried to get a broad outlook in this field from a stand-point of dimensional analysis. Using dimensionless quantities derived from such an analysis, the partial differential equations of heat conduction can be changed to ordinary ones and it is shown that the general solutions obtained in this way include the exact solutions which have been solved likely by chance. Considerations of a dimensionless quantity being a ratio between the effect of latent and sensible heat, give an approximate and very convenient method to obtain a solution sufficiently exact when the value of the above-mentioned dimensionless quantity is large. This report also gives a rule to decide whether the moving velocity of an interface obtained in this way is higher or lower than that which would be given by the exact solution. The numerical analysis following E. Schmidt is also discussed briefly.

著者

馬渕 清資

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.97, no.902, pp.19-23, 1994-01-05 (Released:2017-06-21)

参考文献数

7

著者

伊藤 将利

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 2008.17 (ISSN:24243175)

巻号頁・発行日

pp.11-14, 2008-12-09 (Released:2017-06-19)

著者

奥泉 信克 木村 康治

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 C編 (ISSN:03875024)

巻号頁・発行日

vol.64, no.622, pp.1873-1881, 1998-06-25 (Released:2008-02-26)

参考文献数

14

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Dynamic behavior of smooth hysteretic systems subjected to harmonic excitation is analyzed. Wen's differential equation model for hysteresis, which can be applied to a large class of hysteretic systems, is used. A piecewise power series expression for hysteresis, which was derived from Wen's model assuming a sinusoidal response and weak hysteresis in the previous paper, is extended to the case of the response expressed in terms of constant and higher harmonic components. The method of multiple scales is applied to the equation of motion with the extended piecewise power series terms and the second order approximate solution for the case of primary resonance is obtained. Phase plane trajectories and resonance curves obtained from the solution are compared with the results of numerical simulations and the second order averaging analysis in order to examine the validity of the present analysis.

著者

天寅 喬文 渕端 学

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.18-00399, (Released:2019-06-27)

参考文献数

8

---

In recent years, NOx and soot contained in the exhaust gas of diesel engines become problems. Currently they are elutriated by exhaust gas aftertreatment devices, which make the engine system more complicated. Therefore, we focused on emulsion fuel, which is known as one of the simultaneous reduction technology of NOx and soot. Although emulsion fuels are generally characterized by its water content, some literatures report that the effect on the diesel engine performance could not be controlled by the water content properly. Therefore, we focused on dispersed water droplet diameter as the other factor. In this study, we prepared emulsion fuels of different water droplet diameters and investigated the exhaust gas and power performance of a diesel engine with these fuels. The emulsion fuels consist of light oil, water and surfactant. We added 2.0 vol% of surfactant whose HLB value was adjusted to 6.0 to light oil. The water content was 10 and 15 vol%. We prepared emulsion fuels of three different mean dispersed water droplet diameters. The test fuel was 6 types of emulsion fuel (3 kinds of dispersed water droplet diameter, water content 10 and 15 vol%) and light oil. The diesel engine used in our experiment was of air-cooled, single-cylinder, jerk pump driven direct injection type. The displacement is 320 cc. We measured in-cylinder pressure, ignition delay, exhaust gas emission (NOx, Soot and CO) and power performance (Output power and Thermal efficiency). We found a relationship between the Sauter Mean Diameter of dispersed water droplets (DS.M.D.) and each parameter. The smaller DS.M.D. is, the more the NOx and soot are reduced. On the other hand, the bigger DS.M.D. is, the higher the output and thermal efficiency are.

著者

楠 仁宏 嵯峨 宣彦 永瀬 純也 佐藤 俊之

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 2014 (ISSN:24243124)

巻号頁・発行日

pp._2A1-K03_1-_2A1-K03_3, 2014-05-24 (Released:2017-06-19)

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In recent years, in consideration for danger of secondary disaster at disaster areas, development of rescue robots has been expected. We have paid attention to the mechanism of the peristalsis performed by earthworms and developed a robot using the mechanism. In this research, we developed a robot which recreates the motion of the muscles of earthworms using two kinds of actuators. The feature of this mechanism is that the robot is always able to move a fixed distance even if the space is narrow. In this paper, we propose the mechanism of the robot and consider the three moving patterns of the robot.