Standing waves in thin plates tensioned by in-plane loads subject to high frequency excitation

The problem investigated is that of the response of thin plates subjected to pure tone or wide band frequency excitation. A point load is applied perpendicular to the plates. In the case of isotropic or orthotropic plates excited at high frequencies ring shaped standing wave patterns are observed. No classical explanation exists covering this phenomenon. The present analysis indicates that there are two waves radiating from the excitation point with the same frequency, but at different speeds. One wave, a bending wave, is separated from the other one, a membrane wave.     

Technology education students: e-tutors for school children

E-tutoring refers to individualised learning support mediated by Internet technology. While increased demand for tutors has led to a surge in commercial e-tutoring services, volunteer e-tutoring programs for children are rare. To test the viability of volunteer e-tutoring for elementary school students, 10 undergraduate students enrolled in a technology education (TE) course provided online with instructional support to children in need of tutoring services. Each e-tutor was assigned a specific child, developed a Web Course Tools course and corresponding online activities to improve teacher-identified skill deficiencies, and provided 8 weeks of e-tutoring. Three video conferences complemented online instructional interaction between e-tutor and e-tutee. Children, parents and TE students expressed positive evaluation of the initiative.     

Education in a bi/multilingual setting

Group bilingualism is typically the result of ethnic groups in contact and competition, where one group becomes bilingual, a concomitant condition of the degree of integration. The nature of the relationship is influenced by 1) the origin of the contact situation 2) the degree of enclosure and 3) the degree of control by dominant groups. Migrant groups tend to shift languages after some generations of bilingualism; colonized and annexed groups tend to shift languages at a much slower rate. Bilingual education may have the goal of language maintenance or induced language shift. The paper closes with a discussion of the development of bilingual education from this perspective.     

A study of stearyl alcohol bloom on Dan Hill PVC dolls and the influence of temperature

A study was conducted to investigate white bloom found on more than 130 polyvinyl chloride (PVC) dolls from the 1980s and 1990s produced by the Danish factory Dan Hill Plast A/S. The bloom was discovered on the dolls after 10 years of storage in a climate controlled facility with average temperature at 11–12°C and a relative humidity at 50?±?5%. Analysis of the dolls and the bloom was carried out using Fourier transform infrared spectroscopy, which revealed that the bloom consisted primarily of stearyl alcohol. Subsequent analysis with gas chromatography–mass spectrometry showed a minor presence of cetyl alcohol. It is proposed that the alcohol had been added as a lubricant to aid flow during processing. The stearyl alcohol was almost completely reabsorbed into the PVC dolls following one month storage at room temperature, suggesting that low temperature storage played a decisive role in the appearance of the bloom. It is likely that a decrease in temperature has led to a decrease in compatibility of the stearyl alcohol in the PVC compound, thus promoting its exudation. This paper also discusses an extreme bloom of white crystals on other PVC dolls of unknown provenance.     

CCTV IN THE CURRICULUM

An aspect of work at the Dover ETC Service is the provision of CSE courses in photography, drama and graphic design. While discussing the difficulties of assessing such work, the author mentions the benefits that result from any such group project work, particularly the increased motivation of the less academically able students