Locating contact areas and estimating contact forces between the “Mona Lisa” wooden panel and its frame

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.     

民族理论研究的多学科视野新探索--评王瑜卿的《民族交往的多维审视》

民族理论研究新作《民族交往的多维审视》关注的焦点是少数民族融入城镇化的相关问题。该书以民族交往理论为基础,借用社会共生理论与文化“涵化”理论,思考当今民族交往关系,揭示民族交往过程。该书有针对性地调查取证,采用学科交叉和相互移植的研究方法,综合运用哲学、文学、历史、法学等学科知识,构建起了一个多元学科交叉互用、立体支撑的研究结构。其理论创新在于民族交往的认识论研究,重点提出了民族和谐共处、化解冲突与矛盾的思路对策,为多民族、多国籍的城市社区民族和谐交往提供了有益的借鉴。