On Leonard Control applied to Mine-Hoist

In this study, the general equations of resisting moment of hoist are given; the economical relation between acceleration and retardation may be found from equations [60], [61] and [62]. Taking iron losses into account, the capacity of the hoist motor may be determined, though with some difficulty, from equation [65]. In order perfectly to avoid the mechanical danger, equations (69) and (70) are to be checked. The writer's sincere thanks are due to Prof. E. Aoyagi for his kind instruction

Extinguishment of diffusion flames formed over a porous plate burner using rubber balloons filled with inert gases

We have proposed an inert gas, rubber-balloon extinguishing method which might increase the effectiveness of extinguishing flames and decreasing the amounts of agents needed for fire suppression. Hence, extinguishing experiments have been performed to further clarify possible extinguishing characteristics, mechanisms and scaling effects of this method. Carbon dioxide, nitrogen, argon and helium gases were used as the extinguishing agents. Methane-air and propane-air diffusion flames were formed on two different diameter, round porous plate burner and used as the targets for extinguishment. The extinguishing probabilities were measured, and the extinguishing processes were observed with a high-speed camera. As a result, an effectiveness ranking of an inert gas in the rubber-balloon extinguishing method was in agreement with that of a cup-burner method. Moreover, determinations of extinguishing limits were accomplished, defined as the minimum volume of the inert gas required for successful extinguishment of flames; these limits depended on the balance of the heat loss caused by an inert gas and the heat production within the flame, and also on the forming process of a flammable premixing layer near the surface of the burner. In addition, all the extinguishing limits were represented by a unique, constant relationship depending on the non-dimensional number of the ratio of the heat absorbing rate of the inert gas to the heat release rate of the flame multiplied by the Schmidt number of the fuel species

Preliminary Study of H₂O Adsorption on Cr₂O₃ and Al₂O₃ Surfaces by Ab Initio Cluster Calculations

Adsorption and desorption of water over Cr-oxide and alumina are of great concern with the contamination of stainless steel and gas chromatographic isotope separation. However,the mechanisms of those phenomena have not been fully clarified. A preliminary ab inito study on the behavior of water molecules on the (001) surfaces of α-Cr₂O₃ and α-Al₂O₃ was carried out for small clusters of Me4O4 (Me=Cr or Al) by use of the Gaussian 03 package. It was found that water molecules can be adsorbed molecularly and dissociatively on these surfaces. Molecular adsorption of a H₂O molecule takes place on a metal atom of the cluster as Me-OH₂, with the bond length of about 2.0 Å. Dissociative adsorption occurs by forming Me-OH (on-top site) or Me2-OH (bridge site) and O-H bonds. There appeared a feature that the bond length of Me2-OH is greater than that of Me-OH. Calculated adsorption energies were examined by comparing with the values estimated from the thermal desorption spectra of water for α-Cr₂O₃ and γ-alumina. The ab initio calculations coincided quite well with the observed thermal desorption spectrum for α-Cr₂O₃, whereas they did not for γ-alumina. Further studies are required to clarify the structures of adsorbed species, adsorptiron energies and kinetic processes

A Toulmin's Framework-Based Method for Design Argumentation of Cyber-Physical Systems

The design of cyber-physical systems (CPS) is a promising domain, where the data market is expected to soon penetrate. When engineers focus on only a particular part of data (whether intentionally or not) for establishing a design hypothesis, the design hypothesis may also be supported by data sets in the market. Therefore, the validity of such a design hypothesis cannot be evaluated by the data itself, and can only be accepted by the robustness of the logic behind the design argumentation. Although the validation of the design logic is significant, cognitive aspects (which people have spontaneously) disturb the design argumentation reasoning. Therefore, a design method that overcomes the cognitive aspects is indispensable for the CPS designers. This work proposes a CPS design method using the interaction between logic and data sets with a logic visualization tool, and applies the proposed method to the design of a diagnosis system for semiconductor manufacture. The capability of the proposed method is also discussed and analyzed in this paper

Improvement Of A Beam-bending Viscosimeter For Fast Measurement

The beam-bending method is very useful for the viscosity determination of glasses, but the time spent to run the measurement is usually very long. The present note describes the performance of an improved beam-bending viscosimeter at the support stand and loading rod to get the faster measurements of high viscosity glasses with better reliability and precision. The testing time was reduced from 8 to less than 4 hours to run one measurement at three different temperatures (1100, 1200, and 1300°C), with the precision of almost one order of magnitude better (±0.01 for 1g η in poise).6593028302