Saturated pool boiling of 2-propanol/water mixtures on a 12mm diameter horizontal disk under atmospheric pressure was investigated. The CHF of the mixtures increased up to 1.7times the CHF of water at 3.0 to 4.7 mol% concentrations of 2-propanol. To examine the mechanism of the CHF enhancement in the mixtures, liquid-vapor structures close to the heating surface were measured using a conductance probe. It was found that in the boiling of the mixtures, liquid-vapor structures show strong non-uniformity in the radial direction of the heating surface. The void fractions at 0.1mm to 1mm above the heating surface are small at the central region and large near the periphery of the heating surface. The liquid layer between the vapor mass and the heating surface is considerably thicker than that of water at the central region and becomes thinner near the periphery of the heating surface. This thicker liquid layer is likely to be the cause of the CHF enhancement in the 2-propanol/water mixtures.
In this paper, we propose a filter to satisfy velocity and acceleration limits for arbitrary input signals. The shapes of input signals are sometimes converted into trapezoidal wave in order to prevent an overload on the robot in FA field. Generally, physical protection of equipments, safety and ride quality are achieved with limitations for input signals about some properties. For achieving such limitation, the filters which limit some signal properties are widely used. A filter structure to satisfy velocity and acceleration limits was designed only simple feedback control with the saturation function. However, this structure had a problem that time-lag between the input signal and modified signal is occurred. To solve this problem, we propose a filter structure which is based on the model error compensator. Modified signal which is generated by the proposed filter satisfies the desired signal constraints for any input signals. By the proposed structure, time-lag can be smaller than the signals obtained by the previous method. The effectiveness of the proposed filter is shown by the numerical examples.
In this paper, we propose a filter structure whose output satisfies the velocity and acceleration constraints for any input signals. In the field of factory automation, step signals are sometimes converted into trapezoidal waves to satisfy the intended velocity limitations. This helps the operators avoid overload in industrial robots. In some cases, physical protection of the equipment, safety, and ride quality can be ensured by limiting the characteristics of input signals in actual plants. A signal-limitation filter is proposed for the input signal to satisfy the intended signal limit. In the previous study, a signal-limitation filter structure was provided as a simple unit-feedback control with a saturation function. The filter structure in the previous study had a delay between the input and output signals because it is difficult to design gains considering both the saturating and non-saturating cases. To solve this problem, we propose a novel filter structure that includes feedforward and feedback components. Applying this filter structure with feedforward terms including saturation enables us to fulfill the desired limitations for arbitrary input signals. We evaluated the proposed structure in a signal-limitation filter that simultaneously limits the velocity and acceleration. The simulation results demonstrate the effectiveness of our proposed filter.
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