Slide-blade type air pumps are utilized in printing machines as an air source which provides both the action of air blowing and suction necessary for the paper handling. In the air pump, a large part of the motor power is occupied by the sliding friction between blades and cylinder surface of the casing. So, it is necessary to clarify the mechanism of the friction quantitatively in order to design practical dry air pumps with longer life and less energy consumption.
In the paper, first of all, the sliding force by a single blade was measured experimentally through the axle torque, and its mechanism was made clear. Then, the torque by multi-blades was investigated similarly, and its characteristics which should be affected by chamber pressure were analyzed. As a result, the following conclusions are obtained :
1) . The sliding torque by a single blade indicates a cyclic change with rotor rotation, the absolute value of which is far larger than the theoretical one estimated by the centrifugal force to the blade solely.
2) . The sliding torque by a single blade is affected significantly due to the constraint of the blade movement at the rotor slit. Specifically, the sliding torque is the largest around a point between the maximum protrusion hight and the maximum thrust speed. Therefore, the set angle of rotor slits is an important parameter for the blades behavior.
3) . In actual air pumps with multi-blades, the air pressure in the blade chambers as well as in the bottom space of the rotor grooves seriously affect the blade motion along the rotor slit. Therefore, air holes connecting the bottom of the rotors slits as well as air slots formed on the blade side-face are effective for decreasing the sliding torque.

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In this study, an experimental method of estimating fluid transients by combining a steady-state Kalman filter and an optimized finite element model of pipeline dynamics is discussed. In this method, spatiotemporal distributions of not only the flow rate but also the pressure in a pipe can be estimated from pressure at three points. Furthermore, fluid transients can be estimated without accurate setting of initial conditions, and it is also possible to exclude sensor noise in estimating the pressure and flow rate from the measured pressure including the noise. Steady flow rate was first estimated online in real time. The estimated flow rate was compared with the flow rate measured by a flow sensor. This confirmed that the estimated result coincide with the measurement result well. Next, unsteady flow rate and pressure were estimated offline. For comparison, unsteady flow rates and pressures were simulated with the method of characteristics using the same data. Unsteady pressure was also measured by pressure sensor. This comparison confirmed that the unsteady flow rate and pressure can be estimated even though the input includes sensor noise. Finally, estimation of the pressures and flow rates at uniformly spaced grid points in a pipe were discussed. The estimates showed good agreement with the simulation results. Therefore, it was confirmed that the spatiotemporal distributions of pressure and flow rate can be precisely estimated with the Kalman Filter.

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Railway vehicle pneumatic systems are included in many elements, such as the brakes, suspension, and doors. To date, these systems have been designed through experience, and evaluation of the unsteady characteristics of these systems has not yet been attempted. The railway pneumatic system termed a vacuum toilet serves passenger comfort. To assess the efficiency of this pneumatic system, we measure the pressure and flow rate of the vacuum toilet using an air power meter which applies the principle of the quick flow sensor. We also confirm that it is possible to improve the efficiency of the toilet by changing the pneumatic element. The simulation results approximated the experiment data.

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The spring-driven ball-type check valve is one of the most important components of hydraulic systems : it controls the position of the ball and prevents backward flow. To simplify the structure, the spring must be eliminated, and to accomplish this, the flow pattern and the behavior of the check ball in L-shaped pipe must be determined. In this paper, we present a full-scale model of a check ball made of acrylic resin, and we determine the relationship between the initial position of the ball, the diameter of the inflow port, and the kinematic viscosity of oil. When kinematic viscosity is high, the check-flow rate increases in a standard center inflow model, and it is possible to greatly decrease the check-flow rate by shifting the inflow from the center.

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