Since 2004 an international research group of Wood Technologists has been given by the Louvre Museum the task of analysing the hygro-mechanical state of the Poplar (Populus alba L.) panel on which Leonardo da Vinci painted his “Mona Lisa”, namely verifying the appropriateness of the thermo-hygrometric conditions in its exhibiting showcase, where the microclimate is actively controlled, and assessing the potential consequences of any hypothetical fluctuation. In order to acquire data about the mechanical behaviour of the panel, and to feed and calibrate appropriate simulation models, the team has not only set up a continuous monitoring by means of automatic equipment, but has also performed manual measurements on the occasion of the annual openings of the showcase where the masterpiece is conserved and exhibited. This paper reports about techniques used for estimating the forces acting between the wooden panel and its frame (the châssis-cadre), and their location, such data being of primary importance for evaluating the panel's internal stresses. The contact forces have been calculated on the basis of the local contact pressures, imprinted on a pressure-sensitive foil as a range of saturation values of the colour developed in the contact areas. The forces calculated as above have also been compared with the contact forces between the panel's back face and the crossbeams pressing it against the châssis-cadre, which have been measured by means of a load cell. As could be expected, the results from so different techniques do not strictly coincide; however the agreement is fairly good. 相似文献
The attribute focus in engineering education now adopted by the engineering education accrediting bodies of the US, UK and Australia is based on meeting the assumed needs of professional practice. It is associated with an increasing expectation by employers of work-ready graduates rather than relying on subsequent work-based learning and experience to develop many of the essential professional practice attributes. Yet the scope of the mechanical engineering profession is broad and views of practitioners contributing to debate on attribute requirements are largely influenced by their own often unique professional formation.
In addition, the formative development of the profession in Australia has been significantly influenced by 19th and 20th century UK and US practices, although historically the industrial profile of Australia has been strikingly different. An analysis of current industry distribution of Australian, UK and US mechanical engineers presented in this paper shows continuing, although less marked, differences.
To develop a clearer perception of the profession in Australia, its educational formation, and operational environment, this paper provides a concise study of the formative development of the profession, and presents a breakdown of the industry sectors in which they are currently employed. The effects of momentous global changes in engineering employment and formation over recent decades are also discussed.
Recent changes in engineering employment have included major structural changes to organisations, accelerating technical and educational developments and mounting societal expectations making it imperative that attributes be attuned to the new engineering paradigm as increasing demands are placed on our graduates.
This paper provides an essential foundation for ongoing debate and analysis of attribute needs related to this broadly based engineering discipline. Although presented from an Australian perspective, many issues discussed are applicable worldwide. 相似文献