著者

長野 幹雄 川合 伸明 長谷川 直 北薗 幸一 佐藤 英一

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.863, pp.18-00012, 2018 (Released:2018-07-25)

参考文献数

15

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With the development of spacecraft, the brittle materials like ceramics and glass have been used for significant components especially in optical and thermal systems. However, they are vulnerable to damage by hypervelocity impact of space debris and micrometeoroids. Against a backdrop of increasing number of space debris, impact-damage evaluation on brittle materials become a growing concern. In this study, a series of hypervelocity impact experiments has been conducted to evaluate internal damage propagation mechanism in a fused-silica-glass plate target by impacting a stainless steel projectile with 1-mm diameter in the velocity range around 2 km/s. Damage propagation behavior was observed from two directions simultaneously by means of in-situ shadowgraph coupled with an ultra-high-speed video camera. The observation concentrates on propagation behavior of lateral cracks and that of internal failure. The former is revealed to a mass of small cracks which were generated by passing of the surface stress wave. The latter propagation is affected by the longitudinal and transversal waves, the reflection of the spherical stress waves on the back surface of target. The failure propagates rapidly two times by the reflected waves: first rapid propagation was caused by tensile stress induced by the reflected longitudinal wave, the secondary rapid propagation was caused by shear-compression mixture stress induced by the reflected transversal wave, which was generated by mode conversion of the longitudinal wave.

著者

馬場 康平 岡安 光博

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.17-00570, 2018 (Released:2018-07-25)

参考文献数

11

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Domain switching characteristics of a commercial lead zirconate titanate piezoelectric (PZT) ceramic at high temperature of 100℃ were investigated using an electron backscatter diffraction (EBSD) system. The PZT ceramic consisted of a tetragonal structure with grain size of about 5μm. To analyze the domain switching characteristics, the EBSD analysis was carried out in the same region of the PZT ceramic before and after the heating process. From this analysis, it appeared that each grain is formed by three different domains with different ratio. The area ratio of the domain was altered after the heating process because of the 90° domain switching. To understand clearly the 90° domain switching characteristics, the domain modes were categorized with the angle between the poling direction and c-axis of the tetragonal structure. Although the domain mode was categorized, no clear switching pattern was clarified, i.e., domain switching occurred randomly. Such domain switching mode was attributed to the complicated thermal stress in the PZT ceramic. In order to clarify the domain switching pattern under the heating process, the switching characteristics were investigated in details, in which the grain, having different stress distribution, was selected. The grain selected was constrained in the wide area by the other grains and some region was non-constrained due to the vacancy. From this analysis, severity of domain switching depended on the stress level, e.g., the higher compressive stress, caused by the thermal expansion of the other grains, made the strong domain switching.

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

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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

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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

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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

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

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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

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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

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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

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

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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

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

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

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

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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

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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.

著者

田村 伊知郎 松浦 真一 嶋津 龍弥 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 (ISSN:21879761)

巻号頁・発行日

vol.84, no.862, pp.17-00403, 2018 (Released:2018-06-25)

参考文献数

11

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The ductility factors of nonlinear SDOF systems at Service Limits Ds “using elastic analysis design” in JEAC4601 are investigated, and it was confirmed that the ductility factors depend on the natural frequencies of systems, seismic motions and constant loads. Based on the above results, an acceptance criterion of components to prevent ductile failure and plastic collapse is proposed. The criterion is given as a limit of ductility factor for Service Limits Ds “using elastoplastic analysis design”. The proposed limit of ductility factor allows single state for nonlinear systems, and doesn't depend on the natural frequencies of systems, seismic motions and constant loads.

著者

山田 和明 保田 俊行 大倉 和博

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.17-00288, 2018 (Released:2018-06-25)

参考文献数

28

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The field of multi-robot systems (MRSs), which deals with groups of autonomous robots, is recently attracting much research interest from robotics. MRSs are expected to achieve their tasks that are difficult to be accomplished by an individual robot. In MRSs, reinforcement learning (RL) is one of promising approaches for distributed control of each robot. RL allows participating robots to learn mapping from their states to their actions by rewards or payoffs obtained through interacting with their environment. Theoretically, the environment of MRSs is non-stationary, and therefore rewards or payoffs learning robots receive depend not only on their own actions but also on the action of other robots. From this point of view, an RL method which segments state and action spaces simultaneously and autonomously to extend the adaptability to dynamic environment, named Bayesian-discrimination-function-based Reinforcement Learning (BRL) has been proposed. In order to improve the learning performance of BRL, this paper proposes a technique of selecting either of two state spaces: one is parametric model useful for exploration and the other is non-parametric model for exploitation. The proposed technique is evaluated through computer simulations of a cooperative carrying task with six autonomous mobile robots.

著者

堀 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

vol.84, no.862, pp.17-00555, 2018 (Released:2018-06-25)

参考文献数

19

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The conserved scalar and progress variable have been modified and proposed for spray and engine combustion simulation with chemical kinetics. The global equivalence ratio (GER) and progress equivalence ratio (PER) were proposed as the conserved scalar and progress variable in multi-zone model for engine simulations with chemical kinetics (Babajimopoulos et al., 2005). The combination of GER and PER work in lean mixture without EGR gas. But these would not work under rich mixture or EGR gas conditions. Thus, the modified GER is proposed to apply the EGR gas conditions where CO2 and H2O mix in air. Furthermore, the progress variable based on the chemical energy also proposed with modified GER. The zero-dimensional combustion simulations are done under constant pressure and adiabatic conditions to validate the proposed indexes. The reaction mechanism is the detailed chemistry of n-dodecane. That consists of 1,255 chemical species and 3,075 reactions. The results show that the conventional GER works in any mixture as conserved scalar and is good agreement with equivalence ratio under the ambient gas of air. But, the conventional GER overestimates equivalence ratio in lean mixture and underestimates equivalence ratio in rich mixtures. The modified GER is good agreement with equivalence ratio under the ambient gas of air and EGR gas including CO2 and H2O, regardless of lean and rich mixtures. The results also indicate that the PER works in lean mixtures. But that do not work in stoichiometric and rich mixture. The progress variable based on the mass fraction of some chemical species (Van Oijen and De Goey, 2010) works in any mixture, but the that can not compare the reaction progress between different GER conditions. The proposed progress variable works in any mixture and compares the reaction progress at different GER conditions quantitatively.

著者

伊澤 精一郎 磯 拓朗 西尾 悠 福西 祐

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.18-00132, 2018 (Released:2018-06-25)

参考文献数

23

被引用文献数

1

---

Behaviors of liquid films scattering from a disk-type or cup-type rotary atomizer are studied using computations based on the three-dimensional Smoothed Particle Hydrodynamics (SPH) method. To reduce computational costs while maintaining a high spatial resolution, the computational domain is limited to a fan-shaped region near the edge of the atomizers using a periodic boundary condition in the circumferential direction. Steady inflow is considered as the inlet condition. In both disk- and cup-type cases, the liquid film leaving the atomizer edge becomes wavy in the circumferential direction and forms elongated ligaments, which break up into droplets. When the atomizer is equipped with grooves on its outer edge, the process of ligament formation and droplet break up is strongly affected by the number and shape of the grooves, particularly for the cup-type atomizer, in which the centrifugal force works more effectively. Two ligament formation patterns are observed: one ligament from each groove and a pairing of ligaments from two neighboring grooves. Droplets of uniform sizes are likely to be generated when the former pattern appears. The results suggest that droplets of uniform sizes can be obtained by choosing the appropriate shape and number of grooves.

著者

西尾 宣俊 稲葉 真一 吉田 雄太 佐藤 暁拓 田向 剛 高木 哲郎 飯田 誠

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.18-00042, 2018 (Released:2018-06-25)

参考文献数

15

---

In case of analyzing the wind turbine design conditions and power productions accurately, the wind data at hub height is generally ideated for simulation. Recently, due to the increase in the size of the wind turbine, it is difficult to measure wind data of hub height by the cylindrical observation tower. Therefore, lattice tower mast is adopted and there are cases where high altitude measurement is performed instead of cylindrical tower mast. However, even in case of measuring wind data using lattice tower mast, there are some uncertainty of flow distortions by tower shadowing. This paper shows a study on wind speed correction method of lattice tower mast using CFD simulations (Fluent). As a result of performing the wind speed correction using the inflow wind speed ratio by CFD calculation, the uncertainty of corrected wind speed fell by less than 1 % which is recommended by IEC 61400-12-1.

著者

細谷 和輝 高橋 一成 大家 渓 岩森 暁

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.17-00561, 2018 (Released:2018-06-25)

参考文献数

20

被引用文献数

2

---

Surface modification of polystyrene (PS) dish used as a cell culture substrate is an indispensable strategy to enhance cell adhesion. In general, plasma treatment is employed to enhance the hydrophilic nature on the PS dish surface, and sterilization treatment of the PS dish is performed after the plasma treatment. We reported on a simultaneous process of surface modification and sterilization on the PS dish in a sterilization bag by using active oxygen species (AOS) generated via ultraviolet (UV) lamps, whose wavelength are 185 and 254 nm respectively. Herein, we attempt to investigate the dependency of the distance between UV lamp and PS dish on the surface modification by using the AOS. After exposure of AOS, the oxygen content of the PS dish was increased, whereas the water contact angle was decreased along with the decrement of the distance between PS dish and UV lamp owing to increase in the AOS concentration. Cell adhesion was also enhanced with decrease of the distance between PS dish and UV lamp compared with untreated PS. Especially, chemical states such as atomic concentration and chemical bonding affect cell adhesion rather than the surface wettability. Illumination of the UV lamps and AOS concentration at the PS dish surface affects the resultant cell adhesion.

著者

中佐 啓治郎 山本 旭宏 李木 経孝

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.17-00360, 2018 (Released:2018-06-25)

参考文献数

17

被引用文献数

1

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Argon ion sputter-etching of SUS420J2 and SUS316 stainless steels was carried out at a power of 250W for 10.8ks to form cone-shaped sharp protrusions with bottom diameter of 10-30 μm and fine quasi-column-shaped protrusions with diameter smaller than 500 nm respectively by using a radio-frequency magnetron sputter-apparatus. Effects of two types of plasma-nitriding on gripping ability were examined; one is the nitriding of both steel specimens using nitrogen gas of 0.53 Pa mixed with argon gas of 0.67 Pa at a power of 50W for 1.8 ks to maintain the original sharpness of protrusions, and another is the nitriding of SUS420J2 steel specimen using only nitrogen gas of 1.2 Pa at a power of 200 W for 7.2 ks to obtain the cone-shaped protrusions with round top. The coefficient of static friction, or gripping ability, of the plasma nitrided sharp protrusions of SUS420J2 steel specimen to polyethylene, polyvinyl-chloride, polyethylene-naphthalate sheets and a copy paper was about 1.8, 2.4, 1.1 and 1.5, respectively, at a large nominal compressive stress of 18 kPa. The reason for such large frictional coefficients is due to localized deformation of sheet under the sharp protrusions or piercing of the protrusions into the sheet. Although the sharp protrusions were partly broken, the frictional coefficients of these sheets were still about 1.6, 1.8, 1.1 and 1.4 after the second series of tests, which are more than twice as large as that of the specimen ground with #100 emery paper. The plasma-nitrided round protrusions of SUS420J2 steel and the fine protrusions of SUS316 steel were not broken during the friction tests of the polyethylene sheet and the copy paper but the frictional coefficients are smaller than those of the sharp protrusions. The protrusions with large frictional coefficients can be applied to the surface of a frictional conveying roll.