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Synthesis of SiC nanowhiskers from graphite and silica by microwave heating

Kahar S. M., Voon C. H., Lee C. C., Hashim U., Md Arshad M. K., Lim B. Y., Gopinath S. C. B., Rahman W.

Materials Science Poland

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2016

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Vol. 34, No. 4

770--779

EN

Silicon carbide (SiC) is an important ceramics for engineering and industrial applications due to its advantage to withstand in high temperatures. In this article, a demonstration of SiC nanowhiskers synthesis by using microwave heating has been shown. The mixtures of raw materials in the form of pellets were heated, using a laboratory microwave furnace, to 1400 °C for 40 minutes at a heating rate of 20 °C/min. The characterization process proved that the mixture of graphite and silica in the ratio of 1:3 is an ideal composition for synthesizing single phase β-SiC nanowhiskers. Vapor-solid mechanism was suggested to explain the formation of SiC nanowhiskers by the proposed microwave heating.

2

Safety Management in a Relationship-Oriented Culture

Hsu S. H., Lee C. C.

International Journal of Occupational Safety and Ergonomics

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2012

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Vol. 18, No. 1

35--45

EN

A relationship-oriented culture predominates in the Greater China region, where it is more important than in Western countries. Some characteristics of this culture influence strongly the organizational structure and interactions among members in an organization. This study aimed to explore the possible influence of relationships on safety management in relationship-oriented cultures. We hypothesized that organizational factors (management involvement and harmonious relationships) within a relationship-oriented culture would influence supervisory work (ongoing monitoring and task instructions), the reporting system (selective reporting), and teamwork (team communication and co-ordination) in safety management at a group level, which would in turn influence individual reliance complacency, risk awareness, and practices. We distributed a safety climate questionnaire to the employees of Taiwanese high-risk industries. The results of structural equation modeling supported the hypothesis. This article also discusses the findings and implications for safety improvement in countries with a relationship-oriented culture.

3

Nonlinear transient analysis of point rub effects in a flexible rotor

Lee C. C., Allaire P. E.

Applied Mechanics and Engineering

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1998

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Vol. 3, no 4

571-588

EN

Rubs occur in industrial rotating machinery in common practice. However, the vibration spectrum produced by different rub conditions is very different and not always easy to interpret. This paper presents a nonlinear analysis of a single mass rotor subject to a point rub with dry friction (Coulomb damping) and compares the results to experimental data. Experimentally, subsynchronous vibrations occur at whirl ratios of 1/N(N=2,3,4...) relative to operating speed with shaft orbits of complicated Lissajous shapes. These results have not been fully explained in the literature. A point rub dry friction model is used, different from previous authors. The nonlinear point rub transient analysis used numerical integration of the equations of motion forward in time to determine the rotor response. The results obtained matched the experimental results relatively well in terms of both whirl ratios of 1/N and the Lissajous shapes. Shaft orbits were found to be a mix of forward and backward precession, rather than the strictly backward whirl often cited in the literature for rubs. Orbit frequency spectrums were found using a Fast Fourier transform numerical algorithm. At the whirl ratio of 1/3, the analysis showed that the rotor only hit the point rub during every two out of three shaft revolutions. It was also found that the rub friction coefficient had little effect on the nonlinear transient results for this rotor and rub model.