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ABSTRACTControl 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
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钢液真空循环精炼过程的物理模拟 总被引：2，自引：0，他引：2
魏季和 《上海大学学报(英文版)》2003,7(1):1-17
1 Ｉｎｔｒｏｄｕｃｔｉｏｎ Ａｓａｓｅｃｏｎｄａｒｙｓｔｅｅｌｍａｋｉｎｇｔｅｃｈｎｏｌｏｇｙ ,ｔｈｅＲＨ(Ｒｕｈｒｓｔａｈｌ Ｈｅｒａｅｕｓ)ｖａｃｕｕｍｃｉｒｃｕｌａｔｉｏｎｒｅｆｉｎｉｎｇｐｒｏ ｃｅｓｓｈａｓｂｅｅｎａｐｐｌｉｅｄｗｉｄｅｌｙａｎｄｄｅｖｅｌｏｐｅｄｒａｐｉｄｌｙｉｎｐｒｅｖｉｏｕｓｆｏｕｒｄｅｃａｄｅｓ .Ｗｉｔｈａｃｏｎｔｉｎｕｏｕｓｌｙｇｒｏｗｉｎｇｄｅｍａｎｄｆｏｒｈｉｇｈｑｕａｌｉｔｙａｎｄｈｉｇｈｌｙｃｌｅａｎｓｔｅｅｌ,ｉｔｈａｓｎｏｗｂｅｃｏｍｅ ,ｔｏａｃｏｎｓ… 相似文献
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魏季和 《上海大学学报(英文版)》2003,7(2):97-117
1 Introduction Withuninterruptedlyincreasinginthedemandforultracleansteel,thevacuumcirculation (RH)refiningprocesshasnowbecomeaprinciplerefiningoperationforreducingthecarbonanddegassingofmoltensteel.VariousrefiningtechnologiesusingoxygenorpowderinjectionandblowingintheRHtreatmentformakingultralow carbonandultralow sulphursteelhavebeendevelopedinrecentyears[1 10 ] .Actually ,theRHre finingprocesshasbeenextendedtobecomeamulti functionrefiningtechnology ,whichisenabledtore movecarbon ,oxygen … 相似文献
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王艳 《辽宁科技学院学报》2008,10(2):4-5
常见的与薄板坯连铸工艺相配合的精炼工艺有LF、RH和CAS。通过对三种精炼工艺的适用性分析,探讨了在生产热轧卷板时,利用提高精炼操作水平等措施可以实现LF与薄板坯连铸机的合理衔接;在生产冷轧薄板时,RH与CAS是与薄板坯连铸相匹配的较为合理的炉外精炼工艺。 相似文献
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分析了转炉冶炼轴承钢的技术优势,以GCr15轴承钢为例,采用全铁水脱硫-复吹转炉吹炼-LF＋RH精炼-大截面连铸流程生产轴承钢工艺可行。采用优质铁水并预处理脱硫,有效地控制原料中〔P〕≤0.01%、〔S〕≤0.003%;通过复吹转炉吹炼,使钢中碳-氧反应趋于平衡,弥补了因低拉碳造成的钢中氧含量高的不足;利用LF及RH精炼,使钢材中的有害元素〔Ti〕≤30×10-6、〔O〕≤8×10-6、〔N〕≤38×10-6、〔H〕≤0.8×10-6;通过大截面连铸改善了大规格轴承钢低倍缺陷。 相似文献
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RH和RH-KTB精炼过程中钢液流动和混合特性的研究 总被引：7，自引：0，他引：7
The flow and mixing characteristics of molten steel during the vacuum circulation refining,including RH(Ruhrstahl-Heraeus) and RH-KTB(Ruhrastahl-Heraeus-Kawasaki top blowing) processes,were investigated on a 1/5 linear scale water model of a 90t multifunction RH degasser,The circulation rate was directly and more accurately determined,using a new method by which the more reliable results can be obtained.The fluid flow pattern and flow field in the ladle were demonstrated,observed and analyzed.The mixing time of liquid in the ladle was measured using electrical conductivity method.The residence time distribution in the RH model was obtained by tracer response technique.The influence of the main technological and geometric factors,including the gas top blowing*(KTB) operation,was examined.The results indicated that the circulation rate of molten steel in the RH degasser can be fairly precisely calculated by the formula:Q1p=0.0333Qg^0.26Du^0.69Dd^0.80(t/min),where Qg-the lifting gas flow rate(NL/min);Du and Dd-the inner diameters of the up and down-snorkels(cm),respectively.The maximum value of circulation rate of molten steel in the case of the 30cm diameters either of the up-and down-snorkels for the RH degasser(the “Saturated” rate) is approximately 31 t/min.the corresponding gas flow rate is 900NL/min.Blowing gas into the vacuum chamber through the top lance like KTB operation does not markedly influence the circulatory flow and mixing charateristics of the RH process under the conditions of the present work.There exist a major loop and a large number of small vortices and eddies in the ladle during the RH refining process.A liquidliquid two-phase flow is formed between the descnding stream from the down-snorkel and the liquid around the stream.All of these flow situation and pattern will strongly influence and determine the mixing and mass transfer in the ladle during the refining.The correlation between the mixing time and the stirring energy density is τmε^0.50 for the RH degasser.The mixing time rapidly shortens with an increase in the lifting gas flowrate.At a same gas flow rate,the mixing times with the up-and down-snorkel diameters either of 6 and 7cm are essentially same.The 30cm diameters either of the up-and down-snorkels for the RH degasser would be reasonalble.The concentration-time curve showed that three circulation cycles are at least needed for complete mixing of the liquid steel in the RH degasser. 相似文献
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Stephen Hackney 《文物保护研究》2016,61(1):55-69
Acid-detector (A-D) strips were originally developed to assess the deterioration of acetate film stock, but they can also be used more generally within enclosures to detect volatile acidic pollution. A hand-held reflectance spectrophotometer was used to record the colour of individual strips in order to make consistent and reproducible readings. Calibration was carried out using the yellow-blue axis b*(D65) value in the CIELAB1976 system to measure the colour of A-D strips suspended in enclosed containers over solutions of acetic acid in combinations with glycerol to control the relative humidity (RH). A-D strips were found to be sensitive to changes in high RH (60–90%) but affected little by changes in lower RH or temperatures in the museum display and storage range. A-D strips can be used to establish the presence of volatile acids, record the indication of acid vapour concentration, explore conditions within a container, and to find sources of volatile acidity. They respond very quickly and several can be placed around an object. They therefore show promise for measuring slowly changing conditions, such as seasonal changes and the gradual accumulation of acidity in poorly ventilated containers and spaces. A-D strips proved useful in assessing air quality in storage and display enclosures. Examples and test results are presented. Well-sealed plywood transit frames and storage cases were found to be most polluted with volatile acids. Storage rooms with air filtration systems but filled with wooden objects had significantly reduced air quality. 相似文献
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对X70石油管线钢的生产工艺技术进行试验研究,采用铁水脱硫（DS）一复吹转炉（BFC）一LF-IR钢包精炼一RH真空精炼一板坯连铸（CC）的生产工艺路线冶炼管线钢,钢材实物质量检测结果表明,钢中化学成分控制准确,夹杂物以球型为主,弥散分布;硫、磷、气体含量的控制均达到国际先进水平 相似文献
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蔡莹 《广州体育学院学报》1999,(1)
本文对 80名受试者进行心肺功能及Vo2 max的测量 ,结果显示 :以Vo2 /HR(ml Kg- 1 beat- 1)这一指标以Vo2 /HR (ml Kg- 1 min- 1)与运动成绩更具相关性。提出采用Vo2 /HP来评定运动员有氧代谢能力比Vo2 max更为合理的观点 相似文献
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