我国男子撑竿跳高腾起高度的能量守恒定律分析     

陈光华  高升 《北京体育大学学报》2006,29(2):271-273

通过录像研究、资料查阅、数理分析等方法,依据能量转化与守恒定律,分析了撑竿跳高过程中的能量来源与转化, 总结出助跑、起跳、团身展体、引体推竿这四个过程是动能获得的根源;在整个跳跃过程中,一部分能量被损耗,另一部分转化为身体重心腾至最高点时的势能和过竿时的水平动能, 并提出:加强能量来源与减少能量损失是获得较高腾高的根本方法.  相似文献   

矩阵光学的光路可逆性研究     

张铭 《扬州教育学院学报》2002,20(3):22-25

本文研究了矩阵光学中 ,矩阵逆变换和物理逆光路的逻辑自洽问题 ,揭示了抽象的矩阵操作和实际的物理过程的一致性 ,最后指出 ,它们的统一性 ,本质上在于宏观物理现象的宇称守恒性。  相似文献   

Environmentally-induced stone decay: the cumulative effects of crystallization–hydration cycles on a Lincolnshire oopelsparite limestone     

Belinda J. Colston  David S. Watt  Helen L. Munro   《Journal of Cultural Heritage》2001,2(4)

An investigation has been undertaken at St Andrew’s church, Walpole St Andrew, Norfolk, to establish the underlying causes of the observed stone decay to the upper parts of the six stone piers. The stone decay was first recorded in the early 1930s. The salt-contaminated masonry within the church has been shown to undergo severe salt decay during the summer, with little damage occurring over the winter months. The south aisle piers have been shown to decay 2.5 times faster than the north aisle piers. Although crystallization–hydration cycles have been identified, the rate of decay is at its greatest when the cycling is relatively infrequent. This was not the expected trend. Furthermore, it has been shown that during extended periods where the ambient relative humidity is less than 75%, the rate of decay reaches a maximum. It is the length of this ‘drying’ period that apparently has the greatest influence on the rate of decay and could explain the significant difference in the rate of decay between the south and north aisle piers. The results have serious implications for passive conservation, where it is often recommended to lower the ambient relative humidity to well below the equilibrium relative humidity of the salt contaminant, to avoid crystallization–hydration cycles. Since, at the time of building, the church was situated on the coast, it is possible that the sodium chloride contamination occurred during the building process (1440–1520), particularly since the area was prone to sea-flooding at this time. Alternatively, the salt could have been applied as a treatment during the general restoration of 1897. Whatever the source of the salt, it seems likely that the ambient environment was changed by the insertion of a sealed floor in 1897, which could account for the onset of the salt decay.  相似文献   

广西历代方志的价值及其整理保护     

廖晓云  冼育华 《河南图书馆学刊》2008,28(5)

介绍了广西历代地方志的轸纂概况。分析了广西历代方志的价值,并讨论了广西历代方志的整理与保护问题。  相似文献   

Conservation Heating 24 Years On     

Nigel Blades  Katy Lithgow  Sarah Staniforth  Bob Hayes 《文物保护研究》2018,63(5):15-21

ABSTRACT

Control of relative humidity (RH) for collections care is challenging in U.K. historic houses because they are often highly ventilated with poor heat retention, a porous building fabric and naturally tend to high (60–80%) RH if unheated. The significance of the building means that large-scale modifications and installation of air handling systems may be unfeasible and undesirable for the conservation of the building. In the late 1980s the National Trust, for English, Wales and Northern Ireland, investigated conservation heating as an RH control method that works with the natural environment of historic buildings, mimicking historic heating and requiring only modification of existing heating services or a light touch installation of new heating systems. The National Trust adopted conservation heating as its preferred method for environmental control in historic buildings from the 1990s. This method was presented at the IIC 1994 Ottawa congress on preventive conservation. Conservation heating has since been adopted by many historic house management organisations, particularly across north-west Europe, where it is well suited to the climate. This paper reviews conservation heating developments implemented by the National Trust since 1994, in response to a changing external context, new knowledge and developments in operational practice.  相似文献   

Enhancing Research Impact in Heritage Conservation     

Theocharis Katrakazis  Cath Dillon  Petra Juvan  Stavroula Golfomitsou 《文物保护研究》2018,63(8):450-465

This paper examines how research impact is defined, measured, and generated – with a view to understanding how it can be enhanced within heritage conservation. It examines what is meant by ‘impact’ and how it can be promoted within heritage science through effective inter-disciplinary collaboration. Following a general examination of the current discourse concerning research impact, the study examined: (i) active research networks within heritage science; (ii) research planning and evaluation practices within heritage science; and (iii) the experiences of users (i.e. conservators and other heritage professionals) within research collaborations. Terminologies surrounding the notion of impact and the various phases of the research process were reviewed – from the initial identification of a knowledge gap to the eventual application of new findings in practice. Next, the reach and diversity of research collaborations (as identified through publication co-authorship) were studied to characterise the inter-disciplinary nature of heritage science and its connectedness to users. Findings showed substantial growth in international research collaborations over recent years, predominantly involving academic- and research-oriented institutions – although the engagement of heritage institutions has proportionally decreased. In addition, a worldwide survey of institutional planning and evaluation practices revealed a general reliance on processes driven by the interests of researchers – the systematic consideration of stakeholder opinion and evaluation of research outcomes being less common. Finally, a series of semi-structured interviews with senior heritage professionals explored their experience of collaborative research. The results identified key areas where strategic support is needed to promote user participation and enhance impact. These include training for research readiness, engagement, and impact for both researchers and users; better methods for needs and outcome assessment; affordable open access options and greater diversity of knowledge exchange opportunities. Finally, the need for ethical guidelines for responsible research, and greater emphasis on non-academic impact within research rating systems are discussed.  相似文献   

The Ephemeral,the Essential and the Material in the Conservation of Contemporary Art: Decision-Making for the Conservation of a Work of Art Made with Butterfly Wings     

Rosario Llamas-Pacheco 《文物保护研究》2018,63(8):441-449

This article presents the intervention process carried out on a work of art created by artist Yolanda Gutiérrez Acosta, using a series of ephemeral materials such as butterfly wings and agave thorns. The work, an installation from 2002, is entitled ‘Efímeras’ (‘Ephemera’) and consists of 12 flowers mounted on acetate sheets and attached to the same with vinyl acetate copolymers and acrylic acid esters (Mowilith®). These flowers are installed on the floor in a bed of dried flowers. The conservation of contemporary art can lead to some previously unimaginable problems for restorers. Current works of art are somewhat material in nature, but they also have a conceptual dimension that is essential for their artistic interpretation. The artist’s participation in the decision-making process prior to the restoration was quite useful. The passage of time, its effect on the work, and the need to understand the possibility of the demise and destruction of the work were implicit as of the onset of its creation, such that, according to the artist, we are forced to reflect upon the possibilities of its future state.  相似文献   

Comparison of Three Methods for Evaluating the Condition of the Collection in the Royal Apartments of the Pitti Palace,Florence     

Eleonora Gioventù 《文物保护研究》2018,63(5):355-358

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Managing Uncertainty for Preventive Conservation     

Jane Henderson 《文物保护研究》2018,63(5):108-112

ABSTRACT

This paper examines how conservators engage with uncertainty when creating preventive conservation strategies. It argues that by recognising contexts in which uncertainty will be encountered conservators can develop effective management strategies. A typology of uncertainty explores a range of categories of uncertainty, their experience in preventive conservation and identifies distinct approaches to manage them. Managing uncertainty may include acts of defining its parameters, exposing and resolving through communication or protecting from with contingency. Whatever approach is adopted it must be accepted that uncertainty cannot be avoided. It is important therefore to aim to live well with uncertainty and the paper advocates for preventive conservation applications of strategies recommended in health care for patients with life-threatening illnesses. These strategies include working on things that can be controlled, goal setting, acceptance and factoring in emotions. The ability to identify contexts in which uncertainty is inbuilt should trigger those concerned with preventive conservation to activate strategies developed for managing and living well with uncertainty.  相似文献   

Oddy Test Reloaded: Standardized Test Equipment and Evaluation Methods for Accelerated Corrosion Testing     

Hildegard Heine 《文物保护研究》2018,63(5):362-365

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