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1.
Mechanical properties of wood at different length scales of its hierarchical structure are governed by structural and compositional properties on smaller length scales. This opens up the possibility to use microstructural data for estimating mechanical properties, which are difficult to assess by conventional, destructive testing but are nevertheless of high relevance for conservation practice. Herein, we investigate such microstructure-mechanics relationships for a particular example, namely the load bearing archaeological oak of the Oseberg Viking ship, displayed at the Viking Ship Museum in Oslo, Norway. In order to identify the effects of degradation on the mechanical behavior and their relations to the microstructure, recent oak specimens of different geographical origin (Norway and Austria) are investigated as well. Wood exhibits a cellular structure. Its cell walls are composed of an amorphous polymer matrix consisting of lignin and hemicelluloses and embedded, stiff cellulose fibers. At the cell level, experimental studies comprised microscopic investigations of the cellular structure, chemical analyses of the composition of the cell walls, as well as nanoindentation tests on single cell walls. The same samples were also analyzed on the macroscopic level, where additionally mass density and annual ring data were measured together with ultrasonic stiffnesses. The chemical data clearly indicate deterioration in the archaeological oak, affecting mainly hemicelluloses and amorphous cellulose. At the cell wall scale, however, this does not necessarily lead to a weaker material behavior. The nanoindentation modulus, as a measure of the cell wall stiffness, was found to even increase. This is counterintuitive to our understanding of the effects of chemical degradation. It might be due to possible modification of lignin in the Oseberg oak, and thus have a stronger effect on the indentation modulus than the concurrent weakening of the interfaces between the load-carrying cellulose fibers and the connecting cell wall matrix when analyzing wood at the microscopic level. A similar effect is also observed for the transversal stiffness of macroscopic samples, which increases. In tension-dominated loading modes, however, the degradation of the interfaces is the dominant effect, resulting for example in a considerable reduction of the macroscopic stiffness in longitudinal direction. This underlines the utmost relevance of the loading condition on the remaining load-carrying capacity of degraded wood. On the macroscale, effects of the geographical origin (i.e. growth conditions) on ring characteristics of the oak tissues override the effects of degradation on the mechanical behavior. They have to be carefully extracted in order to come up with conclusions on the effect of degradation from macroscopic test results. The identified microstructure-mechanics relationships provide the basis for–in further research steps–building mathematical models describing the relations between microstructural characteristics and macroscopic mechanical properties and, thereon, for structural analyses of historical wooden objects.  相似文献   

2.
During the excavation of the Etruscan and Roman harbour of Pisa, several shipwrecks were found. The wooden timbers constituting the ship C and ship F (which date back to the first and the second century A.D., respectively, as attested by archaeological findings) were selected in order to collect information about the technological knowledge of the time. Pinus pinaster Aiton was essentially utilised for the planking of ship C and Quercus sp. caducifolia for that of ship F. The choice of timber for the other parts of ship C hull was much more differentiated. Ship C seems to be built in a careful way and its characteristics when added to its overall lightness, seem to reflect its use as a higher capacity boat built for sea sailing. Ship F seems more linked to short voyages in inner fresh waters. The utilisation of different woods was linked not only to the technological characteristics of wood, but also to their easy availability. Palynological analysis, carried out on the clay sediments embedding the shipwrecks, has shown that the flora of Pisa area in that time period would have allowed the acquisition of all the timber species used for both the ships’ construction, with the exception of the fig wood. However, a foreign origin of the timber from somewhere else in the Northern Mediterranean area has not been excluded.  相似文献   

3.
Cheb relief intarsia is one of the most significant artistic techniques used in the early and middle baroque furniture manufacturing. The origin of this exceptional technique is closely tied to the city of Cheb and in a wider perspective, similarly to rondocubism or cubism applied in architecture; it is a branch of decorative arts distinctive just only for Czech lands. Here we report on the findings made on the basis of non-destructive X-ray micro computed tomography (μCT) analysis for determination of the condition and characteristics of the inner structures of an original plate of Cheb relief intarsia. The results of this analysis not only helped to clarify the manufacturing process itself, but also contributed to aim the future actions of the effective intarsia conservation in regard to the spreading internal cracks and defects in the plate discovered by μCT analysis.  相似文献   

4.
Wood identification is a basic information that should interest any wooden artefact. This typically involves invasive sampling, but sometimes sampling is unattainable either because of the object typology or because it is difficult to obtain authorizations. In the present study, reflected light microscopy potential as a non-invasive identification tool for wooden cultural artefacts is assessed on a number of marquetry furniture and small wood carvings. In more than one half of the 13 examined cases accurate wood identification was possible, while the remaining cases yielded information of diagnostic value, making it possible to exclude several potential candidate species. In a number of cases the use of optical filters improved the visibility of character states. Shape and orientation of surfaces influenced the visibility of microscopic characters. The study confirms that reflected light microscopy is a valuable tool for non-invasive wood identification. In many cases it is able to support accurate identification, in others it can anyway provide important information, useful to help decision about supposed species, or to limit the invasiveness of possible further analysis by addressing them on specific features.  相似文献   

5.
In recent years the control and monitoring of works of art has gained more and more importance. In particular, works partially or totally realized with wood, such as polychrome sculptures, painted panels or Crucifixes, are highly sensitive and delicate and thus need a particular attention. The wooden support is, in fact, an essential element for the stability of pictorial layers: the color lies on a preparation, which in turn, is anchored to the wood. Wrong conservation methods, i.e. in an environmental climate that is not controlled, or intrinsic mechanical stresses, can warp such structures, and the effects can be irreversible and destructive to the painted layer. The use of fiber Bragg grating (FBG) sensors for the quasi-distributed, in situ measurement and continuous monitoring of deformations in painted wood panel is proposed. In order to demonstrate the applicability of FBG sensors to painted wood panels, a wooden support, made using the same 15th–16th century techniques, was prepared in the Opificio laboratories. A number of Bragg grating sensors were affixed in several critical points, on the back and front sides and on the strengthening cross-beams, in order to detect deformations in the panel dependent on the variations in the environmental relative humidity (RH). Measurements during the removal of the cross-beams are also reported. The results of measurements have shown the applicability of FBG sensors for the continuous in situ monitoring of valuable wooden objects and works of art.  相似文献   

6.
Along the Umbria-Marche stretch of the Flaminia Consular Road (220 B.C.) several archaeological finds of the most important monumental works, are well preserved. The stones, employed to build many bridges, substructions and sewerages, are represented by carbonatic breccias whose geological environment of formation and source areas had never been established. On the basis of mineralogical, petrographic and micropalaeontological analyses, two groups of these lithotypes employed in Roman age were distinguished: “monogenic carbonatic breccias” only constituted by clasts of the Maiolica Unit (Late Jurassic – Early Cretaceous) and “polygenic carbonatic breccias” made of fragments (in different proportions) of Calcare Massiccio (Early Jurassic), Corniola (Early Jurassic), Maiolica (Late Jurassic – Early Cretaceous) and Scaglia Rossa (Late Cretaceous – Early Paleogene) Units. The possible source areas of the breccias are compatible with stratified slope-waste to scarp-base deposits of periglacial origin belonging to the Upper Pleistocene. In particular, among the seven investigated areas, we pointed out the most probable provenances (Monte Faeto-Colle, Costacciaro, Scirca, Foci, Secchiano) along the flanks of the Apennine Mesozoic chain of the Umbria and Marche regions. Although the Romans could have exploited the whole thickness of some outcrops (now disappeared) of these carbonatic lithotypes at the deepest part of the valleys, we have constrained a local provenance of the breccias so commonly used in the monumental works of the Flaminia.  相似文献   

7.
The paper presents strategies for the conservation of historical textiles in Egypt that have been in uncontrolled storage and display. The silk textile is highly decorated, multicoloured and dates to the Ottoman period, and was exhibited in case # 12014. The textile has various types of deterioration. An examination and analysis of the textile was undertaken in order to develop a plan of conservation treatment. FTIR was used to identify the kinds of dyes and organic stains, and XR-D was used to identify mordants and dust. Light microscope and SEM were used to identify the kind of fibers, their condition and surface morphology. The effects of cleaning materials on the natural dyes were tested. The researcher designed a new metallic frame support system which has advantages over the wooden frames commonly used in Egypt. This presentation will review the conservation treatment step by step. Poultices were used to remove all the sticking cardboard and adhesive. Old conservation repairs were removed. Separated parts were supported. Cleaning included mechanical and wet cleaning. New silk fabrics dyed with natural dyes were used to complete the missing parts. The textile was supported on new linen fabric which was stretched on a metal frame. The method of exhibition will be discussed. Photographs are included to document the conservation process.  相似文献   

8.
This paper builds upon an empirical study of suppliers of online advertising space in France in order to highlight the plurality of quality conventions that organize the activity of market intermediaries. We show that the market is organized around two different quality conventions, the ‘media’ convention and the ‘direct-response’ convention, each equipped with specific efficiency indicators, pricing methods and selling channels. Then we focus on the growing conflict of territory between the two conventions; we analyse the balance of power between the conventions and the arenas where they compete. We observe that the collective action of the defenders of the traditional world is not (yet) sufficient to contain the pervasiveness of the indicators and metrics from the world of direct-response.  相似文献   

9.
Integrated international marketing of films and related merchandise and close financial ties between distributors and roducers have evolved to cope with the risks of piracy, cost containment, opportunism, and revenue uncertainty. Our reading of the evidence is that this system has dominated because of its efficiency. In search of an explanation of why America remains the centre of this institutional and contractual web, we examine the impact of two world wars, the rapid commercialization of new technologies in the United States by aggressive managers, an open financial system and the ethnic diversity, language homogeneity, and size of the domestic market.We are grateful to Elizabet Filleul, Simon Grant, Peter Harcourt, Ian Jarvie and Janet Staiger for their comments but absolve them of any responsibility for the views presented.  相似文献   

10.
Lime renders are of great importance not only to enhance the appearance of the buildings, but also to protect and preserve old masonries. They constitute a specialized system, composed of several layers, in which each of them depends on the others and carries out some specific functions in order to assure a suitable performance of the whole. Knowledge of the traditional materials and techniques, as well as the know-how, is one of the key points in the maintenance and conservation of lime renders and, by extension, of our Heritage. However, the promotion of the use of cement and the industrialization process, which in the case of Spain took place about the 1960's, caused lime mortars to fall into disuse. In this article, classical treatises as well as the state-of-the-art researches were analysed to compile the properties of lime render layers, on the whole. The knowledge of these characteristics is essential to maintain and repair the existing renders as well as to formulate new compatible ones, while assuring their durability and appropriate performance. Lime is the selected binder for these recommendations because it was widely used as drawn from the literature.  相似文献   

11.
This research evaluates the use of microblasting technique with powdered cellulose as a new tool for dry cleaning documents. Different cleaning tests were conducted on three documents with different properties following this new approach and the results were compared to those obtained with traditional dry cleaning with erasers. In order to assess changes caused to the supports, the treated documents were examined both before and after cleaning with optical and 3D stereomicroscopy, SEM-EDS and spectrophotometry. The results allow the conclusion that microblasting with powdered cellulose is a feasible technique to remove surface dirt or grime on paper documents. This research proves that the new use of the technique does not entail changes to the surface properties of the treated supports. Moreover, powdered cellulose is chemically stable and compatible with paper documents, preventing negative long-term effects derived from the presence of rubber residues that may remain in paper fibres when using erasers in dry cleaning treatments.  相似文献   

12.
This paper engages with the question of the new as the first stage in what may, at a later time, turn into an innovation. Taking our cue from John Dewey, the new is here interpreted as a consequence of indeterminacy. We study practices that induce indeterminacy in order to ‘source’ the new. Based on findings from a collective research programme, we distinguish three ways of inducing indeterminacy: configuring situations, creating things and risking valuations. For each of these ways of inducing indeterminacy basic variations are described and discussed in greater detail. The three ways of inducing indeterminacy are shown to correspond to a present-centred concept of time that distinguishes the now from a past and a future horizon. The cases presented affirm the claim that the new is not an inevitable consequence of the increasing entanglement of technoscience and the economy but something that needs to be sought for, cared for and actively produced.  相似文献   

13.
This article explores the multiple modes of valuation that pervade newsmaking in economic journalism. It does so by exploring the different ways in which journalists at Valor Econômico, the leading economic newspaper in Brazil, compete and cooperate in the production of news. Valor is a paradigmatic case for discussing valuation practices in newsmaking since its institutional promise is to produce news of value. How, if at all, do Valor journalists embrace the promise of producing news that generates value? Elaborating on Stark’s (2009. The sense of dissonance. Accounts of worth in economic life. Princeton University Press) idea of dissonance, it is contended that different orders of worth collide and cooperate within Valor newsroom. Moreover, journalists engage in a variety of valuation practices through which these orders of worth are shaped, defined, and refined, reflecting different understandings of economy and society, and different conceptions of what journalism is good for. I argue that Valor’s direction intentionally fosters a plural space of value dissonance in order to improve the quality of news reporting. I emphasise, however, that these dissonances are only productive against a larger background of consonance about what actually there is to disagree about. The article is based on a seven-month ethnography of Valor’s newsroom in São Paulo between 2013 and 2015.  相似文献   

14.
Nicéphore Niépce carried out a lot of meticulous experiments that led him to the invention of photography. In particular, in the 1820s, he obtained heliographs by coating a substrate with a light-sensitive substance, which was then exposed to light under a paper print made translucent with the help of varnish. The objective of the work described here is to determine how Niépce made these paper prints transparent. Did he use his experimental knowledge on photosensitive resins, or did he apply commonly used recipes of his time to make paper transparent? To date, no studies have been carried out on the varnish used by Nicéphore Niépce and no previous research has undertaken analytical investigations on Nicéphore's prints, using Attenuated Total Reflection Fourier Transform Infrared Spectroscopy (ATR-FTIR) and Gas Chromatography/Mass Spectrometry (GC/MS). In this paper, we identify the varnishes used by Nicéphore Niépce on four transparent prints, now belonging to the Nicéphore Niépce museum in Chalon-sur-Saône, France. The varnish he used was based on a diterpenic Pinaceae sp. resin (most probably colophony). The finding is supported by historical knowledge about varnishes.  相似文献   

15.
This paper reports petrographic and chemical data and magnetic susceptibility values for trachytes of quarries recognizable within the Euganean Hills and sets out diagnostic parameters for these rocks. The diagnostic scheme proposed is basic for the definition of provenance of trachytes used in ancient artefacts spread over northern Italy. Trachytes were extensively used by the Romans for paving Via Aemilia, the most important road in the Po Plains connecting Ariminum (present-day Rimini on the Adriatic sea) to Placentia (present-day Piacenza on the Po river). Remains of the trachytic flagstones (basoli) used for paving segments of Via Aemilia crossing Regium Lepidi (present-day Reggio Emilia) and Bononia (present-day Bologna) have been characterised petrographically, chemically and also using magnetic susceptibility data. The discriminating scheme proposed here for the Euganean trachytes has been applied to the data obtained for basoli and thus the provenance of each investigated block has been inferred. The rocks sampled at Regium Lepidi mostly come from Monselice (only a few blocks from Monte Oliveto and Monte Merlo) and those of Bononia come mostly from Monte Merlo and, subordinately, from Monte Oliveto and Monselice (only one sample from Monte San Daniele). The dominant provenance of blocks, which is different in the two colonies distant by less than 50 km, suggests that the two segments of Via Aemilia were not built simultaneously.  相似文献   

16.
There is little information in the conservation literature with respect to artists’ alkyd paints; thus, artists and conservators are somewhat at a loss about how to use and treat alkyds. Recently, analytical methods have been developed to identify the components in these polymers (oil modified polyesters), rates of cross-linking and mechanical properties. Presented in this paper are some of the characterization results of artists’ alkyd paints using THM (thermally assisted hydrolysis and methylation) gas chromatography– mass spectrometry (THM–GC/MS) and Fourier transform infrared spectroscopy–attenuated total reflectance (FTIR–ATR). Four brands of artists’ alkyd paints containing alkyd resin have been analysed; one containing a phthalic anhydride and pentaerythritol based alkyd resin, two containing isophthalic acid and pentaerythritol based alkyd resins, and the final one containing both phthalic anhydride and isophthalic acid and pentaerythritol based resins among the colours studied.  相似文献   

17.
The use of coloured pastes for inlaying marble and limestone wall panels is one of the ornamental techniques that were widely used during the Mamluk period in Egypt (1250–1516 AD). Red and black pastes from Qijmas El-Eshaqe mosque (1482 AD) in Cairo were studied to identify their main components. The study of the samples involved the identification of the pigments, additive materials and organic binding media. The study was performed using various analytical methods such as polarising microscopy (PLM), scanning electron microscopy equipped with energy dispersive X-ray analyser (SEM-EDX), inductively-coupled plasma (ICP-AES), X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR). These complementary analytical techniques provide precise identification of inorganic and organic substances used in the pastes. The results indicated that the red pigment is mainly obtained from red ochre containing hematite, whereas amorphous carbon (bone black and charcoal) was used to obtain the black colour. Both samples contain calcium sulphate, which was used to give some hardness to the pastes. Beeswax was used as an organic medium in both pastes. The study provides the information required for the conservation of the coloured paste ornaments.  相似文献   

18.
The central place occupied by actuarial calculation in insurance is usually understood as resulting from the process of bringing the laws of large numbers to bear on archival data in terms of an ‘insurance imaginary’. However, little attention is paid to the political and broader governmental conditions upon which actuarialism rests. Analysis of fire insurance in Australia indicates that despite urgings from other branches of insurance, the industry did not go down this ‘scientific’ track until well into the twentieth century. Instead, it relied on detailed individual inspection by insurance agents and a process of ‘cumulative dangerousness’ – adding up the multiple hazards discovered in each case and using this as a guide to setting premiums. The result was slow, expensive and cumbersome. But the industry was forced to adopt this approach because the built environment in Australian cities was so underregulated that nothing could be taken for granted. Only when adequately designed and enforced government regulations began to appear after the mid-1920s could fire insurance adopt actuarial techniques for economising uncertainty.  相似文献   

19.
A substantial recent literature has examined insurance as a mechanism for economizing uncertain but potentially catastrophic events. Less attention has been paid to how insurantial techniques for economizing catastrophe have been deployed as political technologies. Focusing on discussions of US flood policy in the 1960s, the present article examines how insurance was used to forge new articulations and accommodations between political government and processes of rationalization. On the one hand, insurance provided a technical solution to problems that had long confronted US policy-makers: How to reduce losses from floods? How to fully compensate individuals who suffered losses? On the other hand, insurance was a device for reshaping the aims and objects of government, and for reframing questions that are more frequently situated at the level of political philosophy: What are the respective responsibilities of individual citizens and government in providing security? What tradeoffs must be made between the provision of security and economic rationality? What values are relevant in orienting public policy? In examining these issues, the article raises questions about standard narratives about the changing relations among risk, responsibility, and security in recent decades, particularly as they relate to neoliberalism.  相似文献   

20.
Judith Butler's work on performativity takes an explicitly Foucauldian approach to politics. The economic performativity literature, in comparison, has been criticised for failing to foreground power. This paper uses a case study of market creation in UK marine fisheries to suggest, after Butler, ways in which a Foucauldian analysis of the exercise of power can inform our understanding of economic performativity.  相似文献   

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