The gas cutting process is one of the main methods used for cutting steel sheets. Gas cutting produces molten steel and it cools down and adheres strongly to the back of the steel material. This adhered matter is called slag and is difficult to remove. In this study, we tried to reduce the viscosity of steel and improve the peelability by applying carbon paste to the steel surface. As a result, it did not contribute to the improvement of the peelability, but the effect of the carbon paste improved fluidity of molten steel and reduced the volume of slag that strongly adhered to the steel sheet. When the carbon concentration of the adhered slag was measured, no carbon remained in the adhered slag, but it was proved that the amount of the adhered slag was reduced by the effect of the carbon paste.

Rolling bearings are used in various machines. Generally, the rotating speed varies in conformity with operational situation and the fatigue life is calculated using the average rotating speed. Furthermore, there is an intended end-usage in which CW and CCW rotations are repeated at short times. In such end-usage, since the rotating speed becomes zero when the direction of rotation changes, the moment in which the lubricant film is unformed exists. In the case of repeated change of direction of rotation, it can be considered that the wear and rise of vibration can be easy to result in comparison with the case of no direction change of rotation. However, study on the rise of vibration in the use conditions for repeated change of direction of rotation is very few. Therefore, this research deals with the effect of repeated direction change of rotation to rise of vibration by measuring the vibration of small ball bearing in the endurance test. In consequence, it was clarified that the bearing vibration increased with larger rate of acceleration in the moment of direction change of rotation and running track at the raceway surface was distinguished.

A structural optimization method of subsystems to realize desired SEA parameters was proposed by the authors in the past studies. This method is based on a combination of SEA and FEM calculation, calculating repeatedly until satisfying the value of objective functions under arbitrary constraints. As a result of applying the proposed method to a simple structure consisting of two flat plates connected in an L shaped configuration, the design variable is taken as the thickness of the FEM element, a subsystem structure with the desired value of the CLF or power flow between subsystems for the one frequency band or multi frequency bands were constructed. However, it is difficult to apply the optimum results to real machine structure because of setting the thickness of the FEM element as the design variable. In this paper, the method is also validated through numerical analyses, using a finite element method, of a flat plate, the plate is grouped into a plural elements, and the each grouped element is set as a design variable, which should take a discrete value, the total mass is taken as a constraint function in order to minimize the vibration power at one frequency band. As a result, in comparison with experimental data, numerical analysis results are qualitatively accurate.

The time-averaged airflow around a mileage competition vehicle was analyzed using computational fluid dynamics in order to optimize the body design to reduce aerodynamic drag and achieve lower fuel consumption. The design parameters were the minimum ground clearance h, the radial clearance of the wheels S_r, and the axial clearance of the wheels S_z. The speeds of the inlet airflow and the ground, relative to the vehicle at rest in the computational domain, were both set to 30 km/h based on the running conditions in the mileage competition. The rotation speed of the wheels was also included in the simulation. The drag exhibits a sharp minimum for a particular minimum ground clearance, h_min, where a remarkable pressure recovery and a decay in the vorticity behind the vehicle body are found. Having optimized the S_r value to achieve a lower drag, the S_z value was then adjusted to keep the steering range of the front wheels. Finally, the pressure drag and friction drag per unit span at the spanwise center were calculated. The pressure drag on the rear body is also found to be minimized at h_min. The validity of the friction drag for the vehicle was confirmed by approximate calculations based on theoretical equations for a turbulent boundary layer above a flat plate.