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1.
《文物保护研究》2013,58(3):169-173
AbstractA complete summary of equations for leakage of enclosures is given, including vapour diffusion through still air in openings, and infiltration of air/vapour/particulate mixture. Stack pressure due to temperature and relative humidity difference drives most infiltration. Experiments confirmed the diffusion and infiltration equations for small and medium-size enclosures. Leakage for a carefully made display case with ordinary materials has been reduced to the microbarometric limit of about 0·03 of an air change per day. Simplified tables and charts of leakage are given for 0·1, 1·0 and 10m enclosures, as a function of crack width, hole width, and wall permeability. 相似文献
2.
《文物保护研究》2013,58(1):8-17
AbstractAbsorbent materials such as wood, paper and cotton stabilize the atmosphere of show-cases against the relative humidity changes caused by temperature variation and by exchange of air with the surroundings.There are several exchange processes between the air in the case and the outside air: diffusion through porous COllstruction materials, air flow caused by temperature and pressure changes and airflow by convection in a show-case whose relative humidity differsfrom that of its environment. The air changes about once a day in show-cases made by conventional joinery techniques. The rate of exchange can be reduced to less than five volumes a year by sealing a show-case so that only one small hole is left for pressure equalization. A dust and sulphur dioxide filter can then be fitted to maintain a pure atmosphere within.In heated rooms without air-conditioning the RH may fall dangerously low in winter. A static method of RH control for a show-case is described. This is a saturated solution of sodium bromide covered by a silicone rubber membrane. 相似文献
3.
《文物保护研究》2012,57(1):1-13
ABSTRACTShortly after a major renovation at the Royal Ontario Museum, it was noticed that the glass panels in many of the new display cases exhibited fogging or hazing on the surface, sometimes in very specific patterns. Cleaning removed the fogging temporarily, but it began to reappear within 12 months. An investigation of fogged glass panels in display cases was undertaken to understand the source of the fogging and to develop an appropriate cleaning method. This included the analysis of residues from glass panels in several galleries, and surface imaging and compositional analysis of glass panels. The fogging residues on the glass panels consist mainly of sodium salts of organic acids and inorganic anions. Sources of the sodium in the residues include air particulate matter and the glass itself. The organic acids and inorganic anions that form salts with the sodium cations likely originate from volatile organic compounds (VOCs) and particulate matter in the air. Examination of the fogging patterns on the glass panels revealed that the sodium salts grow on marks made during cleaning attempts and the manufacturing process. These cleaning and manufacturing marks contain greasy residues that encourage crystal growth. Because of the variation in surface cleanliness, panels with more cleaning and manufacturing residues appear to be heavily fogged while those with less may appear to be unfogged in the museum display cases. A cleaning protocol was tested on two of the glass panels, and was found to remove all traces of grease and fogging residue. 相似文献
4.
ABSTRACTThe need to keep things cool for durability should be the single most powerful influence on storage design. The simplest temperature control is to moderate the outside temperature by a combination of thermal insulation and heat capacity. The low energy storage building is a lightweight, thermally insulated, airtight building put on top of an uninsulated floor slab laid directly on the ground. The thermal insulation is calculated to even out the daily temperature cycle but to allow an annual temperature cycle which is about half the amplitude, but much smoother, than the annual temperature cycle outside. The winter temperature inside will nearly always be above ambient and so will maintain a moderate RH without need for either humidification or dehumidification. The temperature inside in summer will be below ambient and thus will force dehumidification of the infiltrating air. However, the airtightness of the building allows intermittent dehumidification with low energy consumption, less than one kWh/m3 per year. There now exist enough buildings designed on this principle to reassure curators that highly valued collections can be stored in a space with a gentle temperature cycle and with an RH stability as good as air-conditioning usually achieves. 相似文献
5.
ABSTRACTGlass is often seen as a relatively stable material, unaffected by changes in environmental conditions, but recent studies indicate otherwise. Research on the atmospheric deterioration of glass has consistently shown a strong correlation between climate, especially relative humidity (RH), and the rate of deterioration. New studies by the authors have shown that even stable compositions are at risk, when the glasses are exposed to continuous broad fluctuations in RH and temperature. Letting standards slip for the long-term storage of glass can be devastating, eventually leading to irreversible damage that in the final stages can result in the complete destruction of an object. Current research and monitoring of collections at the Corning Museum of Glass indicates that the RH should be within the range of 40–50%. For already crizzled glasses, a tighter control to 40–42% is recommended. Analysis of compositions of already crizzled glasses is ongoing, and hopefully will lead to the identification of at least some groups of glasses that are more at risk. This will help in providing future environmental recommendations for identifiable compositions, selected glass types, or known manufacturers. 相似文献
6.
《文物保护研究》2013,58(4):229-240
AbstractThis paper describes a novel technique to stabilize the relative humidity (RH) of the air inside museum showcases by using a synthetic hydrophobic membrane coupled with a hygroscopic solution in a membrane contactor. RH-monitoring data for two identical test cases, one of them controlled by a set-up with a plane-plate membrane contactor crossed by forced air and lithium chloride (LiCl) solution flows, show a significant stabilizing effect on RH fluctuations. A theoretical model permits forecasts in close agreement with the experimental RH data. Further calculations carried out over a one-year period show that notable damping of external RH variations can be obtained by using a low air circulation rate, small membrane surface area and low solution mass per unit case volume. A more general analytical solution in harmonic conditions is derived and discussed. 相似文献
7.
《文物保护研究》2013,58(4):289-303
AbstractA tube-type passive sampling method has been developed and assessed for the quantification of formaldehyde (methanal) vapours in indoor air. The sampler was designed for use in museums where test sites often include small enclosures with low air movement. The procedure involves collection of formaldehyde vapours in a Palmes diffusion tube containing a paper support impregnated with an acidified solution of 2,4-dinitrophenylhydrazine (2,4-DNPH). After sampling, quantification of the trapped F-DNPH is achieved by high performance liquid chromatography (HPLC) analysis with UV detection at 350nm. To validate the procedure, permeation devices were used to generate formaldehyde-containing atmospheres, 81–2975ppb, in a 20dm3 chamber so that experimentally derived sampling rates could be calculated and compared with the theoretical value. Three 2,4-DNPH solutions were investigated to obtain an efficient and stable trapping solution. Best results were achieved with a 27mg.ml?1 solution of 2,4-DNPH which contained 4·5%v/v orthophosphoric acid. At 55% RH, and with low airflow in the chamber, the experimentally derived sampling rate of 1·34 ± 0·17ml.min?1 was in good agreement with the theoretically derived sampling rate of 1·36ml.min?1 The passive sampling method was repeatable and reproducible with RSD (relative standard deviation) values below 7%for long-term exposures at low air velocities. 相似文献
8.
《文物保护研究》2013,58(4):251-268
AbstractExtensive investigations of the deterioration of the romanesque painted wooden ceiling in the church of Saint Martin in Zillis (Switzerland) have revealed three major active deterioration phenomena: (1) tented flaking of paint layers; (2) flaking of the wheat starch fixative together with parts of the paint layer; and (3) fungal growth. These deterioration processes correlate with the dynamics of the prevailing room climate. Both forms of flaking are mainly driven by fluctuations of the relative humidity (RH), whereas the fungal attack can be related to high average RH and stagnant air. Frequent daily fluctuations in RH of up to 20% in summer are due to visitors leaving the doors open, while fluctuations of up to 25% are related to heating in winter. Given the risks of new consolidation treatments, the aim is to slow the decay processes by influencing the climate in the room. Installation of automatic door-closers reduced fluctuations but led to a rise in RH and a reduction of air movement, causing greater fungal growth. Subsequently, an automatic air-exchange system triggered by absolute humidity values was installed to reduce excess humidity and to exchange stale air without producing major fluctuations in the relative humidity. This kind of 'climatisation' has the advantage of being highly flexible, allowing variation of the rate and scale of exchange; it is, moreover, truly reversible. 相似文献
9.
It has often been observed anecdotally and implied through experimentation that acrylic emulsion paintings accumulate and entrain soils over time due to the inherent mechanical softness in artist's acrylic paint films, through the presence of hydrophilic film components, and by virtue of the ubiquitous presence of surfactant moieties on these film surfaces once they dry. In the present study, it has been this last effect that we have sought to describe more fully in terms of surfactant responsiveness to both temperature and relative humidity (RH). Surfactant hydration and dehydration under varying temperature and RH conditions affects the ultimate partitioning of the surfactant at the paint–air interface, as well as the inherent size, aggregation tendencies, and solubility of surfactant in the bulk paint materials which contain components that are highly responsive to changes in temperature and RH (e.g. polyacrylic or polymaleic anhydride-type dispersal materials). In this work, analytical techniques including three-dimensional microscopy and quartz crystal microbalance with dissipation were used to add to and reinforce current understanding of the physical and mechanical changes to acrylic paint films with temperature and RH. The migration of surfactant at the film surface was studied using desorption electrospray ionization-mass spectrometry and attenuated total reflectance Fourier transform infrared microscopy. 相似文献
10.
ABSTRACT Adsorbent materials can be used for the removal of organic acids from air in storage rooms with heritage collections. The organic acid removal efficiency of two commercially available activated carbon air-filters were tested in situ in two unoccupied stores with densely packed collections. One filter was designed for outdoor type pollutants (Filter A), while the other was designed for organic acids in indoor air (Filter B). Furthermore, the acetic acid removal efficiency of a desiccant silica gel rotor used for dehumidification was measured in a laboratory at different relative humidity levels. Finally, passive removal of acetic acid by silica gel and unfired clay brick were tested in a chamber, and for clay brick at room level as well. Filter B had the highest removal efficiency. The removal efficiency of both filter types depended on the airflow and the filter performance varied considerably in situ from the values reported from standard laboratory tests. Increasing the filter airflow reduced the removal efficiency from 77% and down to 7% for Filter A, and from 92% to 24% for Filter B. There was almost no effect of active air filtration on the concentration of organic acids when this was measured in the middle and in the corner of the storage rooms away from the ventilation inlets. The desiccant dehumidifier removed 98–100% of the acetic acid from the air, independently of the relative humidity. The desiccant rotor will, however, only be running when there is a need for dehumidification and as a result will only periodically remove pollutants. The high acid removal efficiency by dry silica gel was furthermore demonstrated in a chamber test. A clay brick wall in a test room established a concentration gradient across the room and reduced the concentration of organic acids by 56% compared to close to the emission source. 相似文献
11.
《文物保护研究》2013,58(1):31-34
AbstractA stereocamera adapted to a binocular microscope is used to produce stereomicrograph colour transparencies. Such slides can be examined with a viewer or a stereoscope. They can also be projected on to a screen with a special projector and viewed through eyeglasses. Flash bulbs are used to eliminate vibration problems during exposure. 相似文献
12.
ABSTRACTLight sensitive objects will fade on display. Collection managers and curators face the dilemma whether to spread fading over several similar objects or sacrifice one. This paper describes an experiment in which participants were asked how they would want to pass on a collection of seventeenth century hand-coloured maps to coming generations. Results show that while colour changes are hardly visible, both public and professionals do not perceive them as damage and prefer to spread fading. Once fading becomes clearly visible in all maps, the preference shifts to sacrificing one map. The tipping point lies around five just noticeable changes. This information can be used when selecting objects for exhibition. The outcome also implies it would be prudent to assess the degree of fading of much exhibited objects and consider whether and when to choose for a sacrifice strategy. 相似文献
13.
ABSTRACTThis study examined the impact of relative humidity (RH) on the corrosion rate of 129 archaeological iron nails from two sites. Oxygen consumption of individual nails in controlled RH was used as a corrosion rate proxy to deliver quantitative data on corrosion rate as a function of RH. This was negligible at 20% RH, slow up to 40% RH for both sites, and increased rapidly at 60% RH for Roman nails from Caerleon (Wales) and at 70% RH for medieval nails from Billingsgate (London). The nails were digested and their chloride content was determined and related to their oxygen consumption at specific RH values. While a generic pattern of corrosion as a function of chloride was identified, for any single concentration of chloride corrosion rate was not predictable. Desiccation is in common use to control post-excavation corrosion of archaeological iron; quantifying how differing levels of desiccation changed corrosion rate provided a scaled tool for identifying corrosion risk, estimating object longevity, and calculating cost benefit for storage options. 相似文献
14.
AbstractTwenty-two commercial coatings were chosen, based on their film-forming mechanisms, to study the equilibrium concentrations of volatile organic compounds (VOCs) and their emission rates at steady state. Concentrations of acetic acid (ethanoic acid) and total VOCs were measured using a thermal desorption unit coupled with a gas chromatograph. Almost all coatings released acetic acid, but at different rates. Coatings formed by oxidative polymerization were found to generate a high level of acetic acid at both equilibrium and steady state. The acetic acid equilibrium concentrations from the coatings formed by the other types of mechanism studied tended to be similar to those from red oak, an acidic wood. In a steady-state situation, most of the coatings applied on aluminium or on red oak had acetic acid emission rates lower than that of red oak alone, with the exception of the red oak coated with pigmented films formed by coalescence. The wide range of acetic acid equilibrium concentrations and emission rates for films formed by coalescence is due to the mixture of porous resin, extenders and free acetic acid in the formulations. Consideration should be given to allowing a sufficient drying period (three to four weeks) before using coated enclosures, in order to reduce the VOC concentrations within the enclosures. 相似文献
15.
Although not much has been written about older adults' use of academic libraries, they experience challenges navigating these considerable physical and online library spaces. Members of a university lifelong learning community were recruited for a 10-week diary study. They were asked to record their real-time information seeking behaviors related to their study groups, and the challenges they faced looking for or using information. They were also asked to rate their enjoyment to determine whether the joy of engaging in community learning extends to the information seeking process. Findings from sixteen diarists show that they sought information primarily on a specific topic, person, or book. They used a variety of resources but found books and periodicals most useful. They struggled with trust, technology, time management, library anxiety, information overload and dissemination. With increased understanding, librarians can be better equipped to reach older adults that are doing scholarly research and contribute to their success. 相似文献
16.
基于混合云的高校图书馆存储方案研究 总被引：1，自引：0，他引：1
随着高校图书馆数字化建设的推进,产生了大量宝贵的数字资源。高校图书馆正面临越来越大的存储压力,现有的DAS、NAS和SAN三大类存储技术各有缺点,渐渐不能很好地满足高校图书馆日益增长的存储需求。高校数字资源根据性质可分为四大类,各类具有不同的存储需求。基于混合云的存储方案,可以针对不同类的资源,采用不同的存储策略,在存储访问速度、动态拓展容量、安全备份、异地容灾等方面都能很好地满足现在高校图书馆的存储需求。 相似文献
17.
W. Fredrick Limp 《Archives and Museum Informatics》1999,13(3-4):325-340
Geographic Information Systems (GIS) are a rapidly developing suite of computer based technologies that allow the storage, manipulation, display and integration of a wide range of spatially based data. This chapter reviews some of the more significant applications of these technologies in archaeology and historic preservation and suggests future trends. It is arguably the case that space and time are the two central dimensions of our record of the past. Science has fundamentally influenced our understanding of this record through the development and improvement of ways to measure and understand time. GIS and related methodologies present methodologies that are improving our abilities to measure and understand space. 相似文献
18.
方洁 《现代图书情报技术》2004,20(2):87-88
在信息技术中，将每条记录的中文可检词或标题、内容经过独特处理，做成“全息压缩码”做为唯一标识。该技术运用在计算机文献检索系统中可大大提高检索速度，优化空间配置，广泛用于倒排文档、查重、记录对比等多个领域。 相似文献
19.
James M. O'Toole 《Archival Science》2002,2(1-2):45-61
This article explores the relationship between records and various expressions of political and social power. Records are
often made and used for explicit, instrumental purposes, designed to put into effect the plans and desires of those with the
upper hand in certain relationships. They may also be used to enhance subtler forms of symbolic, emotional, and psychological
power. Drawing on a selection of historical examples, the essay argues that record making itself can sometimes be as potent
as any particular records resulting from that process. The essay concludes with some speculations on how these powers inherent
in records may be changing in the context of current technological developments. 相似文献
20.
论文从政府信息资源的有效揭示和长期存储两个方面，探索了电子政务环境下政府信息资源的有效供给保障机制。政府信息资源的有效揭示包括信息资源的目录体系和定位描述体系两方面内容；信息资源长期存储不仅涉及复杂的技术问题，而且是对国家行政的一种挑战。 相似文献