In Japan, the capacity and the efficiency of the steam turbine have been remarkably increased since 1950s. It was the technology on the long last blade of the low pressure steam turbine that made it possible. At present, the longest last blade made of steel in Japan is 50 inch long for 3600 rpm turbine, 74 inch long for 1800 rpm turbine. These long blades have been developed by the own technology of the Japanese turbine maker, and the Japanese technology on the long last blade is leading in the world. The development of the longer last blade requires the cutting-edge technology from the aspect of the fluid dynamics, the material strength, the vibration engineering, and so on, because the longer last blade causes the increase of the steam velocity and the centrifugal force, the decrease of the natural frequency, and so on. This paper describes the history and the prospect on the technology required to develop the last blade of the steam turbine, focusing on the aspect of the mechanical design.

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This article deals with the progress of the sound and vibration research of rolling bearings in Japan. The literature mainly cited is written in Japanese. The focus in sound research is the early research, characteristics and generating mechanism of ball bearings, cage sound, squeak in cylindrical roller bearings, sound of defective bearings, contamination noise and sound life. In the vibration research, the early research, rolling element (ball or roller) passage vibration, natural vibration of the outer ring, natural vibration of the cage, vibration caused by geometrical imperfections, nonlinear vibration, abnormal vibration of grease lubricated ball bearings, vibration of defective bearings, damping and squeeze film damper are explored.

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In the 1980s, active magnetic bearings attracted attention because of their benefits that include contact-free support, no lubrication and low energy consumption, and their industrial applications were extensively studied. In the 1990s, the latest control theories were applied to magnetic bearings, and bearingless drive technologies were established. Magnetic bearings were increasingly applied to industrial machinery and started to find use in artificial hearts. The number of researchers engaged in research on magnetic bearings rapidly increased in Japan, and many achievements were reported. Currently, however, less research is being carried out. In this article, Japan's contribution to the research and development of magnetic bearings is reviewed, particularly key works in the early days of magnetic bearings, from various aspects such as control, rotordynamics, self-sensing, bearingless drives, bearing loss, touchdown bearings, industrial applications, and standardization.

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An induction motor and synchronous motor are applied as a source of drive for machines such as power plants, home appliances and cars. Recently, electrical efficiency have been improved and mechanical structures have become lighter and smaller. As a result of these trends, mechanical vibration and noise are increasing. Vibration and noise caused by electromagnetic force must be reduced to provide a comfortable environment. To satisfy these needs, a system to simulate vibration and noise precisely and effectively at the mechanical design stage is needed. Such a simulation system would reduce the time needed for experimentation and reduce the length of development periods and costs of production.

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The studies of the cracked rotor demonstrated by Japanese researchers started in early 1980s and many papers have been reported. The characteristics of these Japanese papers are: A group of papers investigated the vibration of the practical machinery and the estimation of the position and depth of the crack was tried in the quite early time, Another group of papers used a simple rotor model and investigated the vibration caused by the crack theoretically considering the nonlinearity involved in the crack's characteristic. In the following, these studies of the cracked rotor are divided in the groups, the studies on the vibration analysis of the cracked rotor using simple rotor model, the studies on the vibration analysis of the rotor system with the breathing crack, the studies on the modeling and detection method of the crack and case study of the cracked rotor, and reviewed in detail.

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This article introduces research on nonlinear rotordynamics in Japan. In most cases, the nonlinearity treated there was weak and it was approximated by a power series of low order. Firstly, the research on various nonlinear resonances due to the weak nonlinearity is introduced. Next, those on more complicated nonlinear phenomena, such as entrainment, internal resonances, chaotic vibrations, nonstationary vibrations, and more complicated systems, such as cracked rotors and continuous rotors, are explained. Then, research on phenomena due to strong nonlinearity is introduced. Various vibration suppression methods where the nonlinearity plays an important role are also explained. Finally, studies on the models representing helicopters and wind turbines are explained.

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In this review work, the history of Japanese balancing study is described on the subjects of low speed balancing, high speed balancing, field balancing and computer aided balancing. In addition, rotordynamics researches related to balancing technique are reviewed. The contributions of Japan for development of ISO Standards concerned to balancing are also described.

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This paper presents the comparative study of various color space models to determine the suitable color space model for detection of green sweet peppers. The images were captured by using CCD cameras and infrared cameras and processed by using Halcon image processing software. The LED ring around the camera neck was used as an artificial lighting to enhance the feature parameters. For color images, CieLab, YIQ, YUV, HSI and HSV whereas for infrared images, grayscale color space models were selected for image processing. In case of color images, HSV color space model was found more significant with high percentage of green sweet pepper detection followed by HSI color space model as both provides information in terms of hue/lightness/chroma or hue/lightness/saturation which are often more relevant to discriminate the fruit from image at specific threshold value. The overlapped fruits or fruits covered by leaves can be detected in better way by using HSV color space model as the reflection feature from fruits had higher histogram than reflection feature from leaves. The IR 80 optical filter failed to distinguish fruits from images as filter blocks useful information on features. Computation of 3D coordinates of recognized green sweet peppers was also conducted in which Halcon image processing software provides location and orientation of the fruits accurately. The depth accuracy of Z axis was examined in which 500 to 600 mm distance between cameras and fruits was found significant to compute the depth distance precisely when distance between two cameras maintained to 100 mm.

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The purpose of this study is to design and control a thick shape memory alloys (SMA) actuator to achieve fast position control with two connected SMA wires. In the past, research had focused on position and force control of thin SMA wires, because they can be cooled fast in air and as it is easy to obtain fast response speeds for SMA actuators in this manner. However, the cooling time increases for thick SMA wires, making it difficult to obtain fast position responses. Phase resistance feedback control (PRFC) minimizes cooling time by shortening the long latency time of thick SMA wires. Compared with binary control, experimental results here show that a rate increase of 18% is achieved using this new method. A new displacement-resistance model which normalizes both resistance and displacement is used to estimate the total output displacement of this new SMA actuator.

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A method for reducing the vibration of a rotating cylindrical tank with elastic supports is studied by considering the case where a stationary circumferential flow relative to the tank is created by inserting rotating ring plates whose rotational speed differs from the tank's rotational speed. It is shown that the vibration can be reduced when the flow's relative velocity is negative. The relative velocity appears not only in the inertial and Coriolis terms of the Navier-Stokes equations but also in the dynamic boundary condition on the liquid surface. It is found that the vibration reduction can be caused by the relative velocity that appears in the dynamic boundary condition on the liquid surface. A semianalytical method is presented for the viscous rotating sloshing problem, for which it is customary to resort to numerical methods. The method is verified by comparing with earlier results available for the case with no stationary circumferential flow relative to the tank. This method transforms the viscous rotating sloshing problem into only several ten ordinary differential equations, thereby reducing computational efforts significantly.

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This paper presents a sliding mode control using a nonlinear sliding surface (NSS) to design a robust tracking controller for a quad-rotor helicopter. An NSS is designed to provide a variable damping ratio for the closed-loop dynamics of the system to achieve a quick response and low overshoot performance. The dynamics of the quad-rotor helicopter is derived by the Newton-Euler formulation for a rigid body. The global stability of the proposed control strategy is guaranteed on the basis of the Lyapunov stability theory. The robustness and effectiveness of the proposed control system are demonstrated experimentally, providing comparative results with a conventional linear sliding surface. The NSS provides robust tracking control under significant wind gusts.

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The paper proposes multiple magnetic suspension systems. The concepts are presented by using their basic models. They are classified according to multiple structure, power amplifier and coil connection. According to the first item, they can be divided into series and parallel. This paper mainly treats the latter. The controllability and the observability of each parallel suspension system are discussed based on its mathematical model. The concept of self-sensing magnetic suspension is stretched to the multiple systems. The feasibility of parallel magnetic suspension is demonstrated by simulation

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