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論文

論文
天田, 重庚 ; 寺内, 泰
出版情報: 日本機械学會論文集. A編.  65  pp.2418-2423,  1999-12-25.  日本機械学会
概要: application/pdf<br />Journal Article<br />The cross section of main frame structure is preferable to be a cylinder for plants and animals in order to adapt to their environment. There are some exceptionals. One of those is a hemp palm branch. It has an up side-down isosceles triangular shape. Since the hemp palm branch has unusually large leaves and a relatively slender branch stem as compared with other trees, the branches must be subjected a large bending moment. A triangular cross section must be a solution for that problem, which can reduce the induced stress about 30% under a bending stress. Furthermore, the branch is a composite material reinforced by strong fibers. It also constructs a functionally graded structure on fiber distribution. This structure provides a higher strength in the critical loded region than the induced stress there. 続きを見る
2.

論文

論文
舩津, 賢人 ; 糟谷, 紘一 ; 白井, 紘行
出版情報: 日本機械学會論文集. B編.  65  pp.4009-4014,  1999-12-25.  日本機械学会
概要: application/pdf<br />Journal Article<br />We calculated the flow-field and surface response condition of a planetary probe entering the Jupiter atmosphere, Within the region behind a detached shock wave, the blunt nose is heated to high temperature. So that, the numerical results were obtained under a viscous-shock-layer analysis. To protect the probe against high temperature condition and to reduce the heat flux, which includes convectional and radiative heat transfer, we used the ablation of C/C composite materials. This simulation included mass injection, radiative transfer, diffusion, and viscous effects. The radiations included were molecular bands, atomic lines, and continuum processes. It was found that carbon ablation materials were effective in reducing the radiative heat flux. 続きを見る
3.

論文

論文
長屋, 幸助 ; 湯澤, 秀人 ; 村上, 岩範
出版情報: 日本機械学會論文集. C編.  65  pp.4653-4659,  1999-12-25.  日本機械学会
概要: application/pdf<br />Journal Article<br />Since a commutator of the DC-motor is divided into a number of segments to have the torque in the circumference direction, the currents in the coils of the rotor vary and have alternative waves during the rotor rotation even in a constant input voltage. The currents become sharp waves, so that they have high frequency component. This implies that the rotor shaft and the case of motor are excited electromagnetic forces with high frequency components. Since high frequency noises are loud when they are input to human ears, so that when high frequency vibrations are suppressed, noises become small. From the situation, this paper discusses a method of noise reduction of Dc Motor. In the method, the current waves are controlled to be sinusoidal waves. The method and the control algorithm are given. In order to validate the method, experimental tests are carried out. It is proven that our method is applicable to the motor noise control. 続きを見る
4.

論文

論文
白井, 紘行 ; 田部井, 勝稲
出版情報: 日本機械学會論文集. B編.  65  pp.3806-3813,  1999-11-25.  日本機械学会
概要: application/pdf<br />Journal Article<br />Based upon a collisional and radiative process theory, and synthetic spectra for argon plasmas, the experimental method for spatial properties of Ar plasma jets was presented, and applied to diagnostics for micro Ar plasma jets for fine cutting. A plasma torch had a nozzle of 0.7 mm in diameter and a discharge length of 2 to 10 mm, and was operated with an arc current of 10 to 30 A. Data from a CCD image processor and Mach-Zehnder interferometer were dealt with an Abel transformation to obtain true spacial profiles of electron density and temperature, and heavy particle temperature. Electron temperature in the main flow was found to be about 12 000 to 13 500 K, electron density of an order of 10^<16> cm^<-3>, both increasing with an arc current. It was also found that heavy particle temperature was significantly lower than electron temperature in the nozzle exit region and increased to coincide with electron temperature downstream. Experimental relation of electron temperature and density could be approximated well by that calculated from steady-state collisional and radiative processes. 続きを見る
5.

論文

論文
長谷川, 和之 ; 茂木, 俊夫 ; 天谷, 賢児 ; 新井, 雅隆
出版情報: 日本機械学會論文集. B編.  65  pp.3831-3837,  1999-11-25.  日本機械学会
概要: application/pdf<br />Journal Article<br />Behavior of a spray combustion in a hot air was studied experimentally. A kerosene spray was injected from swirl atomizer into a hot air stream. The air temperature was controlled from room temperature to 1 100 K which was higher than the self-ignition temperature of a kerosene spray. Flame shape and temperature distribution were measured to characterize the spray combustion appeared in the hot air stream. Flow state around the spray was visualized by a Schlieren method to analyze the behavior of the air entrainment into the flame. Furthermore, Mie scattering from the spray droplets by irradiation of the laser beam was observed to visualize the spray concentration in a flame. As the result, ignition point was shifted to the upstream side with an increase of air temperature. When the air temperature became higher than 800 K, the blue flame appeared at the bottom portion of the flame. Penetration of the spray became shorter with an increase of air temperature. Spatial distribution of the spray which were not vaporized in a flame was strongly affected by the air temperature. 続きを見る
6.

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論文
松原, 雅昭 ; 伊藤, 勲 ; 坂本, 賢治 ; 小棚木, 光明 ; 吉川, 州彦
出版情報: 日本機械学會論文集. A編.  65  pp.1902-1907,  1999-09-25.  日本機械学会
概要: application/pdf<br />Journal Article<br />This paper describes strength evaluation of Al_2O_3/SUS 304 joints subjected to interlaminer shear at elevated temperatures. The jig developed enables us to evaluate shear strengths of ceramics/metal joints at elevated temperatures. The shear strengths of them decrease with increasing temperature. The crack generally initiates at the upper and lower sides of the interface, a brazing filler. It grows into Al_2O_3 after stable growth and becomes unstable till 873 K (I C type fracture). The crack propagates along the interface till unstable fracture from 1 173 K (II type fracture). The crack behavior shows a mixed mode of I C and II types at 973 K and 1 073 K (IC+II type fracture). Larson Miller Parameter is valid for creep rapture tests under shear loading. The fracture modes are the I C type under the condition of low temperature and short time and the II type under the long-term condition. 続きを見る
7.

論文

論文
田部井, 勝稲 ; 白井, 紘行 ; 高草木, 文雄
出版情報: 日本機械学會論文集. B編.  65  pp.2996-3001,  1999-09-25.  日本機械学会
概要: application/pdf<br />Journal Article<br />Light emission properties of xenon-water cavitation in circular orifice flows were investigated experimentally and theoretically. The emission was enhanced by dissolving a small amount of Xe gas into water, and its spacial pattern was taken by a chilled CCD camera and an image intensifier. A spectrum of cavitation emission was measured by a spectrometer with a photon counter. Based upon the collisional and radiative theory for plasmas and a two-temperature model, synthetic spectra were calculated for emission of a collapsing xenon bubble at the minimum radius. It was found that the light emission pulsated and was intense around the flow axis a little downstream of the orifice, and the experimental spectrum was predominated by continuum and its intensity distribution was very similar to the theoretical ones with electron temperature of about 12000 K to 14000 K. Mean emission energy per unit pulse was estimated experimentally to be smaller than 5×10^<-9> μJ/nm・sr at the wavelength of 450 nm, which is consistent with the plasma conditions from the emission spectrum. 続きを見る
8.

論文

論文
熊谷, 哲 ; 佐藤, 春樹 ; 吉田, 英生 ; 竹村, 正紀 ; 青木, 和夫 ; 高田, 保之 ; 中川, 勝文 ; 工藤, 一彦 ; 岸浪, 紘機 ; 井上, 剛良 ; 多田, 幸生 ; 香月, 正司
出版情報: 日本機械学會論文集. B編.  65  pp.2566-2575,  1999-08-25.  日本機械学会
概要: application/pdf<br />Journal Article
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論文

論文
小島, 宏行
出版情報: 日本機械学會論文集. C編.  65  pp.2659-2664,  1999-07-25.  日本機械学会
概要: application/pdf<br />Journal Article<br />In this report, first, the nonlinear equations of motion of a horizontal one-link flexible robot arm are obtained by use of the mode functions of a cantilever beam with a mass. Then, the algorithm of the desired signal planning of the joint angle for the purpose of the reduction control of residual vibrations of the flexible robot arm is derived by use of the initial and final conditions of the flexural displacement of the flexible link and the constraint conditions of the desired signal of the joint angle during the acceleration and deceleration terms as well as the linearized equation of motion of the flexible robot arm. The rotation control system of the flexible robot arm is constructed with the desired signal planning for the joint angle and the PD controller. Furthermore, the numerical simulations of the rotation control of the flexible robot arm have been carried out, and it is confirmed that the residual vibrations of the flexible robot arm can be effectively reduced by the present desired signal planning for the joint angle. 続きを見る
10.

論文

論文
長屋, 幸助 ; 小林, 譲二 ; 今井, 勝仁
出版情報: 日本機械学會論文集. C編.  65  pp.2713-2720,  1999-07-25.  日本機械学会
概要: application/pdf<br />Journal Article<br />This paper presents a method of micro-vibration control of milling machine heads by use of vibration absorber. The principle used in the paper is different from usual absorbers. In the present absorber, an auto-tuning vibration absorber is presented in which the absorber create anti-resonance state. When the anti-resonance is used, the damping has to be significantly small, so it is difficult to suppress higher modes. To suppress higher modes, the present article uses autotuning magnetic damper. It damps higher modes, but it also increase first modal vibration. Then a method of optimal auto tuning control is presented in which both principal and higher modal vibrations are suppressed. Experimental tests are carried out for a real milling machine, and cutting tests are also performed. 続きを見る