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Simple VCO with Negative Voltage-Frequency Relation
Sawai Pongswatd,Amphawan Julsereewong,Kitti Tirasesth,Hirofumi Sasaki,Yan Shi 제어로봇시스템학회 2008 제어로봇시스템학회 국제학술대회 논문집 Vol.2008 No.10
A simple voltage controlled oscillator (VCO) with negative voltage-frequency (V-F) relation is presented in this paper. The realization technique is based on the use of commercial available devices to generate tunable sawtooth and square wave signals. Decreasing the control voltage linearly increases the output oscillation frequency. The proposed VCO consists of operational transconductance amplifiers (OTAs) and an RS Flip Flop. Experimental results showing the circuit performances are agreed with the expected values. The usefulness of the proposed circuit is demonstrated through application example with reducing the output ripple waveforms of a buck converter.
Sawai, Kana,Nomaguchi, Yutaka,Fujita, Kikuo Society for Computational Design and Engineering 2015 Journal of computational design and engineering Vol.2 No.3
This paper discusses an optimization-based approach for the design of a product platform for industrial three-axis linear-type robots, which are widely used for handling objects in manufacturing lines. Since the operational specifications of these robots, such as operation speed, working distance and orientation, weight and shape of loads, etc., will vary for different applications, robotic system vendors must provide various types of robots efficiently and effectively to meet a range of market needs. A promising step toward this goal is the concept of a product platform, in which several key elements are commonly used across a series of products, which can then be customized for individual requirements. However the design of a product platform is more complicated than that of each product, due to the need to optimize the design across many products. This paper proposes an optimization-based fundamental framework toward the design of a product platform for industrial three-axis linear-type robots; this framework allows the solution of a complicated design problem and builds an optimal design method of fundamental features of robot frames that are commonly used for a wide range of robots. In this formulation, some key performance metrics of the robot are estimated by a reducedorder model which is configured with beam theory. A multi-objective optimization problem is formulated to represent the trade-offs among key design parameters using a weighted-sum form for a single product. This formulation is integrated into a mini-max type optimization problem across a series of robots as an optimal design formulation for the product platform. Some case studies of optimal platform design for industrial three-axis linear-type robots are presented to demonstrate the applications of a genetic algorithm to such mathematical models.
Phase Transition of PbZrO3 Fine Particles Synthesized by Using the Oxidant-Peroxo Method
Shinya Sawai,H Tanaka,K Tomita,M Kakihana 한국물리학회 2007 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.51 No.2I
We present results of powder X-ray diraction and DSC measurements of the antiferroelectric phase transition in PbZrO3 .ne particles (down to about 40 nm) synthesized by using the oxidant-peroxo method. With decreasing particle size, the pseudo-tetragonal distortion (1¡cT=aT) at room temperature showed an abrupt decrease below 50 nm, though an apparent decrease in the phase transition temperature was not observed with the temperature-dependent X-ray data. A thermal analysis showed that upon a decrease in the particle size, the endothermic peak on DSC curve associated with the phase transition became broader and shallower and the latent heat decreased, with decreasing peak position temperature. The diusive nature of the phase transition in the .ne particles is discussed, taking account of the grain size distribution in the sample.
Seiko SaWai The Korean Home Economics Association 2002 International Journal of Human Ecology Vol.3 No.1
According to the Labor Standard Law in Japan which was enacted after World War II in 1947, all work hours for adult men, women, and youth were set at a maximum of eight hours per day and forty-eight hours per week. In other words, a six-day work week, with only one-day off, was set. Now we are in the full five-day and two-day off school system. The five-day school week influences on our home life. Students are highly enthused by the new system, in looking forward to their personal time they now have to play with friends, to relax, or just watch TV. To implement this new five-day school system positively and effectively, we should see the point at issue related to the two-day off system from a different angle, which suggests that we should see far ahead into the future.