著者

柏山 礼興 坂本 啓 田中 宏明 大熊 政明 石村 康生

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.863, pp.17-00566, 2018 (Released:2018-07-25)

参考文献数

15

---

This study aims to develop an actively deformable space antenna system for radio astronomy around 100GHz. In order to reduce the thermal deformation in active control mechanisms composed of multiple materials, a method to cancel the mismatch of the coefficients of thermal expansion (CTE) is proposed and tested. The CTE mismatch between piezoelements and Super Invar structures is cancelled by adding another metallic part. For effective CTE cancellation, this study clarifies the cause of thermal deformation induced by the preloading mechanisms for a piezoelectric stack actuator. In addition, it shows the effect of the dimension tolerance of the piezoelements is significant, but still manageable by the proposed CTE cancellation method. The effectiveness of proposed method is validated by the use of finite-element analysis, prototyping models, and thermal deformation measurement experiments.

著者

森 浩一 深谷 和貴

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.863, pp.18-00136, 2018 (Released:2018-07-25)

参考文献数

20

---

Spherical Acoustic Black Hole (ABH), a kind of acoustic metamaterial, has been made in the new configuration to control three dimensional propagation of acoustic wave and its characteristics have been investigated by experiments and numerical simulations. ABH is new sound absorber composed of shell and absorptive core. Shell guides the incident acoustic wave into the core and ABH traps acoustic wave. Moreover, shell matches the characteristic impedance to the medium around ABH at the surface, which can enlarge absorption area without reflection. The experimental model of spherical ABH is constructed by stacking urchin-like shaped layers made with a 3-D printer on the assumption that the sonic crystal theory (Torrent and Sánchez-Dehesa, 2006, 2007) is valid in new structure. To evaluate reflection and transmission of ABH quantitatively, sound pressure around ABH was measured and angle averaged reflection coefficient and angle averaged insertion loss (Elliott et al., 2014) were calculated. Also, Glass Wool Sphere made of the same material as core of ABH and Rigid Sphere made of the same material as shell of ABH were measured in the same way and ABH was compared with them. The results of experiment and finite element method analysis show spherical acoustic black hole can decrease reflection due to impedance matching. Moreover, it can change the propagation direction of acoustic wave due to refractive index distribution and a large acoustic ratio region caused by the small refraction was observed.

著者

坂口 歳斗 土井 幸輝 西村 崇宏 藤本 浩志

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.863, pp.18-00119, 2018 (Released:2018-07-25)

参考文献数

29

---

Acupuncturists determine muscle stiffness by pressing their fingers down. To shorten the palpation time and minimize discomfort to the patient, a good palpation technique is required to determine the stiffness of the patient's muscles with as few presses as possible. However, palpation is dependent on the experience of the practitioner. Therefore, an investigation of human hardness discrimination characteristics is necessary to provide some quantitative guidance. In this study, to determine the relationship between different numbers of presses and the accuracy of discriminating hardness, we investigated the differential threshold of hardness for different numbers of presses (1, 3, or 5). We used 7 elastic test pieces, each with a different Young's modulus, as the presented stimuli. We conducted an experiment using the constant stimuli method to calculate the differential threshold of hardness as an evaluation index of hardness identification. In the experiment, the participants repeatedly pressed for either 1, 3, or 5 sets by using 2 presented stimuli and then distinguished the hardness of the stimuli. The results of the experiment showed that when the pressing forces were 5 and 10 N, as the number of presses decreased, the differential threshold of hardness increased. However, when the pressing force was 15 N, the differential threshold of hardness was small regardless of the number of indentations. This knowledge will be useful for the improvement of the palpation technique in acupuncture schools. For example, the index of the hardness discrimination characteristic used in this study may be used as a quantitative numerical target and for performance evaluation.

著者

首藤 登志夫 高橋 健洋

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 B編 (ISSN:03875016)

巻号頁・発行日

vol.70, no.698, pp.2663-2669, 2004-10-25 (Released:2011-03-03)

参考文献数

13

被引用文献数

8 11

---

One of the authors has proposed an HCCI combustion engine system that was fueled with dimethyl ether (DME) with a high cetane number and methanol-reformed gas (MRG) with a high anti-knock property in the previous research. In the system, both DME and MRG are to be produced from methanol by onboard-reformers utilizing the exhaust-heat from the engine. High overall thermal-efficiency has been achieved over a wide operable-range by both the lean HCCI combustion and the waste-heat recovery. While the MRG used in the research was the thermally decomposed methanol, methanol can be reformed to various compositions of hydrogen, carbon monoxide and carbon dioxide. This research aims to find the optimum MRG composition for the system in terms of the ignition control and the overall thermal efficiency. Characteristics of the HCCI combustion of DME and four types of MRG model-gases are experimentaly analyzed. The overall thermal-efficiency was also evaluated for ideal reforming conditions for each case.

著者

横山 眞樹 北山 哲士 河本 基一郎 野田 拓也 宮坂 卓嗣 越後 雄斗

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.863, pp.18-00162, 2018 (Released:2018-07-25)

参考文献数

22

被引用文献数

2

---

In sheet forming, the blank holder force (BHF) has a direct influence on product quality. A high BHF leads to tearing, whereas a low one results in wrinkling. For successful sheet forming, the BHF should be adjusted. Recently, the variable BHF (VBHF) that the BHF varies through stroke is recognized as one of the advanced sheet forming technologies. On the other hand, slide velocity (SV) that controls the die velocity is rarely discussed in the literature, and the SV should also be taken into account for the successful sheet forming. A high SV can achieve the high productivity, but wrinkling occurs. The VBHF trajectory and SV are unknown in advance, and the trial and error method is widely used. In this paper, design optimization approach using computational intelligence is adopted to determine them for achieving the high productivity. The processing time is taken as the objective function to be minimized for the high productivity. Numerical simulation in sheet forming is so intensive that a sequential approximate optimization using radial basis function network is adopted to determine the optimal solution. Based on the numerical result, the experiment using AC servo press (H1F200-2, Komatsu Industries Corp.) is carried out. Through the numerical and experimental result, the validity of proposed approach is examined.

著者

上田 昭夫 渡邉 淳 宮嵜 美弥子 久保 愛三 松岡 裕明

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.83, no.847, pp.16-00295-16-00295, 2017 (Released:2017-03-25)

参考文献数

18

---

The purpose of this study is to understand the nature of one of the oldest gears used in traditional Japanese clock. Today's gear manufacturing technology in Japan came mostly from Europe and America, but we do not know exactly, when and how the gears were manufactured for the first time in Japan. It is interesting to search for this history. It is also exciting to study the tooth profile, precision and accuracy of the gears, and materials of the gears at that time. So far, there have been some studies performed for the mechanism of traditional Japanese clocks/watches, but not for gears. Fortunately we have a chance this time to investigate gears for Japanese watch drive that was made in 1688. Tooth profile and pitch error were measured, and transmission error analysis was also performed. It revealed that the precision of the watch was extremely high without any rust for more than 300 years, even though they were all handmade by Japanese mechanism technician named Sukeza-emon Tsuda the III. In the old days, there was no study on conjugate tooth profile theory available, but mysteriously, tooth profile was nearly made in the form of cycloid. Moreover, the gear material investigation was very interesting: The texture of the gear material was very homogeneous and grain size is far smaller than that of today's comparable steel kind. Impurities in it were very small and scattered well in the matrix. The steel was surely made by Japanese sword smith. The ore of the steel was perhaps sand-iron and it was refined with pine charcoal. The steel was forged and forged by hand very hardly. As the result the quality of the steel of 1688 looks far better than today's industrial steel. This research enabled us to discover how Japanese gear technology was born and developed.

著者

木村 直人 岩附 信行 池田 生馬

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.863, pp.18-00092, 2018 (Released:2018-07-25)

参考文献数

12

被引用文献数

2

---

Linkage mechanisms with 1 DOF consisting of links and lower pairs cannot completely generate the specified output motion. In order to solve that problem, the novel kinematic pair with 1 DOF is developed. This kinematic pair consists of two surfaces in line contact with each other and can generate relative rolling motion along the specified spatial trajectory. Thus, it is called the spatial rolling contact pair. The relative rolling motion along an arbitrary trajectory is specified so as to satisfy the kinematic condition of the spatial rolling motion. Rolling contact surfaces which can generate the specified motion are designed based on ruled surfaces of the instantaneous screw axis. Some norms to evaluate stability of rolling contact between designed pairing elements are introduced, and the pairing elements are constrained by many linear elastic elements so as to satisfy them. Some examples of the proposed kinematic pair are designed, and one of them is manufactured as a prototype. By some experiments, it is confirmed that the prototype generates the specified rolling motion and keeps rolling contact by designed elastic constraint. Finally, it is revealed that a spatial 4-bar mechanism with the spatial rolling contact pair can completely generate the specified output motion and can be synthesized more easily than the mechanism synthesized by conventional methods.

著者

野中 朋美 中野 冠

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.79, no.798, pp.408-417, 2013 (Released:2013-02-25)

参考文献数

24

被引用文献数

1

---

This paper evaluates CO2 emissions generated during the manufacturing phase of global production network and discusses requirements analysis of green sustainable policies of global production network to prevent carbon leakage arising from transnational production. It calculates CO2 emissions from electricity used in manufacturing, emissions during transport from mining to manufacturing countries and emissions during transport from manufacturing countries to market. A case study of electric vehicle (EV) production includes outcomes calculated CO2 emissions in the manufacturing phase and transportation phase: for production in China, India, Thailand, Germany, Japan and Mexico to market in Japan, German and Singapore. It is illustrated that CO2 emissions during manufacture of EVs vary significantly, depending on the carbon intensity from electricity generation and each country's technical efficiency, and transport has a minor influence on emissions.

著者

松永 拓也 柴田 和也 越塚 誠一

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.864, pp.18-00197, 2018 (Released:2018-08-25)

参考文献数

29

被引用文献数

7

---

The particle methods are suited to simulate fluid flow problems with large boundary deformation. The moving particle semi-implicit (MPS) method is one of the representative particle methods for incompressible flow. In recent years, the MPS method has received a great deal of attention in various fields of science and engineering. However, the numerical treatment of complicated wall geometry is still an open question. The conventional approaches have severe issues in handling arbitrary shape or calculation accuracy. In these circumstances, this study has been done to propose a novel numerical treatment of solid wall boundary in the MPS method. In this approach, the wall contribution in the discretization scheme is described in a form of volume integral over object domain. Thus, arbitrary-shaped boundaries represented by a polygon mesh can faithfully be considered. Moreover, since the distribution of physical quantity inside object is given by linear extrapolation, it satisfies the prescribed boundary condition with high accuracy. While the volume integral cannot be numerically evaluated with affordable computational cost, it can be transformed into a boundary integral form based on the divergence theorem. The derived boundary integral can be calculated with reasonable cost and acceptable accuracy using a projection technique and the Gaussian quadrature. The proposed method has been examined through several numerical test cases in 2D and 3D. As a result of the numerical tests, the present method is shown to have considerably higher accuracy compared to conventional methods, and its validity is verified.

著者

又吉 均哉 水内 郁夫

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 2016 (ISSN:24243124)

巻号頁・発行日

pp.2A1-09b1, 2016 (Released:2017-06-19)

---

Harvesting is a hard work among farm works. Although one of means to reduce time and effort is automation, there are very little examples of automation for crops which are harvested carefully and politely. In case of harvesting such crops, moving obstacles such as leaves out of the way or holding a branch is required. We propose a dual-arm harvesting robot which can do such tasks. Moreover, we focus on a cherry. Holding a branch is required while pulling a cherry's pedicels to harvest a cherry. This paper describes a dual-arm robot which can hold a cherry tree's branch while harvesting cherries.

著者

松田 圭司 佐々木 隆志 佐伯 淳 岡 智美 山中 文夏

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

巻号頁・発行日

vol.2016, pp.2P1-17a2, 2016

---

<p>Nowadays we can have many kinds of rich hardware platform with modern operating system and large memory, but traditional microcontrollers are still key components to implement functions to interact with real world including environmental sensing and physical computing. Without fundamental knowledge and experience of this technology layer, it is difficult to realize an idea no matter how wonderful it is. Nevertheless, we do not have enough systematized educational support for students of general high school course, apart from industrial course. This paper reports a practice of educational support to motivate high school students on learning electronic circuit and microcontroller programs through designing and building small-scale model satellite called CANSAT. All activities are offered in high school science club.</p>

著者

古賀 将哉 宮里 和良 松永 三郎

出版者

一般社団法人 日本機械学会

雑誌

スペース・エンジニアリング・コンファレンス講演論文集 2016.25 (ISSN:24243191)

巻号頁・発行日

pp.1A5, 2016 (Released:2017-06-19)

---

衛星から地上局へ届く RF(Radio Frequency) 信号は,ドップラ効果による周波数のずれがあり,地上局との距離や衛星の姿勢によって地 上局での受信 C/N(搬送波対雑音比) が変化する.しかし地上試験においてこれらの影響を含めることは難しい.そこで本研究では,ソ フトウェア無線を用いて,軌道・姿勢データやアンテナ利得パターンから,時々刻々と周波数や C/N が変化する衛星の RF 信号を再現 するシミュレータを提案・開発する.このシミュレータにより,実際の地上局を用いて RF 信号レベルの通信試験を行うことができ,地 上局システム全体の信頼性を高めることができる.実際に開発したシミュレータを用いて,普段の衛星運用と全く同じ手順で,運用オ ペレータの訓練を行うことが出来ることを示す.

著者

阿部 豊 青木 一義

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.712, pp.2864-2869, 2005-12-25 (Released:2011-03-03)

参考文献数

10

被引用文献数

3

---

It is expected to manufacture new materials under the micro-gravity environment in space. Under the micro-gravity environment, holding technology of molten metal is important to manufacture new materials. There are previous studies about droplet levitation by the acoustic wave for the holding technology. However it is still unknown experimentally and analytically how the acoustic wave act on the levitated droplet. In the present study, the technology to handle the material in space by the ultrasonic wave is developed and the simulation technique to evaluate the acoustic wave field and the movement of the droplet in the acoustic field. Therefore the followings are the purposes of present study. At first, the characteristics of droplets holding by the ultrasonic standing wave under normal gravity environment and micro-gravity environment is investigated. Secondary, numerical simulation is conducted to clarity the characteristics of ultrasonic standing wave. Finally, the force committed to a droplet is investigated by reproducing a movement of the droplet.

著者

阿部 豊 青木 一義

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.70, no.692, pp.1072-1077, 2004-04-25 (Released:2011-03-03)

参考文献数

4

被引用文献数

1 4

---

It is expected to manufacture new materials under the micro-gravity environment. Under the micro-gravity environment, holding technology of molten metal is important to manufacture new materials. In the present study, the technology to handle the material in space by the ultrasonic wave is developed. However, it is difficult to hold a high temperature object by ultrasonic standing wave due to temperature gradient. Moreover, it is also important to measure the physical properties of the material by non-contacting. Therefore the followings are the purposes of present study. At first, the characteristics of droplets holding by the ultrasonic standing wave under normal gravity environment is investigated. Secondly, the surface tension of the droplet is estimated by measuring surface oscillation. Thirdly, the viscous coefficient of liquid droplet is calculated by the damping constant of the droplet. Finally, numerical calculation is conducted to clarity the characteristics of the high temperature object holding in space.

著者

松永 拓也 柴田 和也 越塚 誠一

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.18-00197, (Released:2018-08-03)

参考文献数

29

被引用文献数

7

---

The particle methods are suited to simulate fluid flow problems with large boundary deformation. The moving particle semi-implicit (MPS) method is one of the representative particle methods for incompressible flow. In recent years, the MPS method has received a great deal of attention in various fields of science and engineering. However, the numerical treatment of complicated wall geometry is still an open question. The conventional approaches have severe issues in handling arbitrary shape or calculation accuracy. In these circumstances, this study has been done to propose a novel numerical treatment of solid wall boundary in the MPS method. In this approach, the wall contribution in the discretization scheme is described in a form of volume integral over object domain. Thus, arbitrary-shaped boundaries represented by a polygon mesh can faithfully be considered. Moreover, since the distribution of physical quantity inside object is given by linear extrapolation, it satisfies the prescribed boundary condition with high accuracy. While the volume integral cannot be numerically evaluated with affordable computational cost, it can be transformed into a boundary integral form based on the divergence theorem. The derived boundary integral can be calculated with reasonable cost and acceptable accuracy using a projection technique and the Gaussian quadrature. The proposed method has been examined through several numerical test cases in 2D and 3D. As a result of the numerical tests, the present method is shown to have considerably higher accuracy compared to conventional methods, and its validity is verified.

著者

泉 丙完 澤口 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C編 (ISSN:18848354)

巻号頁・発行日

vol.79, no.803, pp.2651-2663, 2013 (Released:2013-07-25)

参考文献数

20

---

After products have been released to markets, from marketing competitions, not only functional improvements but also cost reductions are requested in improvement designs. But many of engineers are feeling difficulties to satisfy both of them at same time. We propose a process for improvement designs to satisfy these different kinds of features by using information integration method. Information Integration method is an evaluation way which is based on concept of Shannon's information theory. In this method, different kinds of features can be compared in a common measure called “Information”. We apply this method to evaluate functions and costs in improving designs. We also propose an optimizing process for improvement design based on this method. By comparing evaluation items in this method, next target for improvement can be automatically selected without personal subjectivity. We have confirmed effectiveness of this process in a case study of electric shaver's improvement design. This study also makes up practical design processes with our previous studies “Practical Cost Reduction Methods based on TRIZ” and “Functional Improvement Methods based on Expert Engineers' Thinking Way”.

著者

上原 賢祐 齊藤 俊

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.18-00218, (Released:2018-08-01)

参考文献数

13

---

Electroencephalogram (EEG) which has a chaotic fluctuation is difficult to analyze. However, quantitative analysis is sufficiently possible since EEG behavior is deterministic dynamics. Our method identifies EEG model parameters experimentally in consideration of chaotic dynamics of EEG. The purpose of this study is to examine the specific characteristics of model parameters. Validation of the method and investigation of characteristics of model parameters were conducted based on alpha frequency EEG data in the relax state and stress state. The results of the parameter identification with the time sliding window for 1 second, the nonlinear mathematical model is shown to produce outputs that can closely match the complicated experimental EEG data. Further, the results showed that the existence of nonlinear term in the EEG analysis is important and the linearity parameter shows a certain tendency as the nonlinearity increases. Furthermore, the activities of EEG become linear on the mathematical model when suddenly changing from the relax state to the stress state. Therefore, it is the effective analysis method that can calculate the degree of concentrate from the dynamics of EEG signal directly. The results suggest that our method may provide useful information in various field including the quantification of human mental or psychological state, diagnosis of brain disease such as epilepsy and design of brain machine interface.

著者

福田 敏男 小林 寛

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

巻号頁・発行日

vol.52, no.481, pp.2437-2442, 1986

被引用文献数

1

---

Based on a previous paper, an attitude control method of the Vroid is dealt with here, under some conditions, so that some of the modules should satisfy the constraints for the robotic shape and attitude, since it is sometimes required that mobile robots must carry something and/or liquid containers in a restricted moving mode. The assumptions are that (i) the Vroid has six degrees-of-freedom, including the freedoms of the rotational joint of the first link and the moving wheels, which were not treated in the previous paper ; (ii) the central link must be kept in the horizontal position as a constraint, which yields five degrees-of-freedom in Vroid ; (iii) Vroid moves along a slope. The problem is formulated as a linear programming problem minimizing the total applied moments at joints, subjected to constraints. Then the proposed control method gives a solutions for the control sequence of the Vroid for various terrains.

著者

本多 正明 武居 昌宏 都 徳照

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.843, pp.16-00241, 2016 (Released:2016-11-25)

参考文献数

16

---

The flow characteristics of a vertical axis wind turbine with the hybrid blade which has the wing section with cutout trailing edge for purpose to make advantages of the drag type and the lift type wind turbine have been investigated by measuring the velocity vector fields using the conditional sampling PIV. The experimental apparatus is constructed using the PIV measurement system with the conditional sampling device and a new hybrid vertical axis wind turbine model installed in a circulating water channel. Four experimental conditions as the tip velocity ratio 0.5, 1.0 1.5 and 2.0 are investigated. The flows around the turbine which influence the efficiency of the vertical axis wind turbine are defined by the measured velocity vector fields. Moreover, the alternations of the angle of attack and the relative flow speed ratio of the rotating blades in the measured velocity vector fields are calculated by analyzing the mean velocity vectors along the circumference of rotating blades. The influences of the flow over the torque generated on the blades are clarified as follows. The drag torque increases, and the advantage of the hybrid blade is effective under the conditions of the tip velocity ratio 0.5 to 1.0. And the lift torque decreases under the conditions of the tip velocity ratio 0.5, and the lift torque increases under the conditions of the tip velocity ratio 1.0.

著者

杉野 詠一 小嵜 貴弘 髙橋 雄三 李 仕剛

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.862, pp.17-00519, 2018 (Released:2018-06-25)

参考文献数

17

被引用文献数

1

---

Power assist devices are worn by users, directly transmit actuator power to the users’ bodies, and can deliver assistance in activities of daily living, such as load lifting. In this study, we built a wearable power assist device for lower limbs driven by pneumatic actuators. Pneumatic power assist devices are safe for users, owing to the compressibility of air; however, the weight of the devices and assist torque often have a negative effect on the wearer’s body balance. Here, an assist control strategy is proposed for the pneumatic power assist device. In this strategy, the relationship between the lower-limb joint angles and the center-of-gravity (COG) of a human body is represented based on a simplified human body model during squatting. Assuming that the anterior and posterior movement of the COG follows the knee joint flexion and extension, the desired COG position is calculated from the knee joint angle measured with a sensor. The desired hip and ankle joint angles are found with the desired COG position, and the desired assist torque is obtained with these joint angles based on the human body model. The power assist device based on this principle was worn by research subjects, and its assistive performance was evaluated through experiments from the viewpoint of the COG fluctuation and muscle activity reduction.