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Toshiharu Kazama,Hayato Sasaki,Yukihito Narita 대한기계학회 2010 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.24 No.1
Temperatures of three bearing and seal parts of a swash plate type axial piston pump were measured simultaneously using a slip ring with thermocouples' amplifiers. The rotating cylinder block had five thermocouples, the swash-plate had four, and the valve-plate had four. Three sets of pistons with different diameters were prepared. Hydraulic mineral oil with VG22 and a water–glycol type hydraulic oil with VG32 were used as test fluids. The maximum discharge pressure was 20 MPa; the maximum rotational speed was 25 rps. The inlet oil temperature was 20-40°C. Temperatures and temperature differences between the bottom-dead-center and the top-dead-center increased concomitantly with the discharge pressure. For larger piston clearance ratios, the temperatures rose monotonically. The bearing and seal parts were markedly hotter than the discharge oil. Temperatures rose much less using the water–glycol type oil than when using the mineral oil.
REDUCTION OF PREVIEW DISTANCE IN LANE-KEEPING CONTROL
Keisuke Kazama,Kohei Nishizaki,Yuta Shirayama,Hiroyuki Furusho,Hiroshi Mouri 한국자동차공학회 2017 International journal of automotive technology Vol.18 No.4
Lane marker detection is indispensable for a lane-keeping-control algorithm. However, it is impossible to detect lane markers when the curvature of the lane the vehicle is travelling on is large or when there is another car in front of the vehicle with short distance. For lane marker detection, it is desirable to set a preview point close to the vehicle. Therefore, by analyzing the block diagram of driver-vehicle system, we propose a method to reduce preview distance without lane tracking performance deterioration by increasing preview points from the conventional one point to two points. Furthermore, it is revealed that driving along a corner with constant curvature without steady-state deviation and arbitrary design of tracking dynamic characteristics become possible by increasing preview points.
Toshiharu Kazama 유공압건설기계학회 2021 드라이브·컨트롤 Vol.18 No.4
Viscosity of hydraulic oils decreases due to loss reduction and efficiency increase of fluid power systems. However, low viscosity is not always appropriate due to the induction of large leakage and small lubricity. Therefore, a detailed study on the optimum viscosity of hydraulic oils is necessary. In this study, based on the thermohydrodynamic lubrication theory, numerical simulation was conducted using the slipper model of swashplate-type axial piston pumps and motors. The viscosity grades’ (VG) effects of oils on power losses are mainly discussed numerically in fluid film lubrication, including changes in temperature and viscosity. The simulation results reveal that the flow rate increases and the friction torque decreases as VG decreases. The film temperature and power loss were minimised for a specific oil with a VG. The minimum conditions regarding the temperature and loss were different and closed. Under various operating conditions, the film temperature and power loss were minimised, suggesting that an optimum hydraulic oil with a specific VG could be selected for given operating conditions of pressure and speed. Otherwise, a preferable operating condition must be established to determine a specific VG oil.
Fundamental Characteristics of Onboard Bandwidth-Variable FFT Filter Bank
Yamashita, Fumihiro,Kazama, Hiroshi,Nakasuga, Yoshinori,Ueba, Masazumi 통신위성우주산업연구회 2000 Joint Conference on Satellite Communications Vol.2000 No.-
Voice service is currently the main service in mobile satellite communications, but in the future, there will be a demand for high-data rate services offering multimedia contents. Therefore, an onboard processor capable of handling services of various data rates is required. In the present study, it is assumed that a non-regenerative onboard processor will be used. The onboard processor must have functions to filter signals and convert their frequencies in a channel-by-channel manner. An FFT filter bank satisfies these requirements. However, the conventional onboard FFT filter bank is only applicable to signals of constant bit rate. Hence, the onboard bandwidth-variable filter bank that can handle many signals of various bit rates is proposed. The principle of operation of the bandwidth-variable FFT filter bank is described, then the BER performance of an FPGA-implemented design is evaluated.