共查询到19条相似文献,搜索用时 156 毫秒
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在进行质量量值传递时,空气浮力修正成为重要的影响量。本文通过对空气中质量测量的基本原理分析和折算质量计算公式推导,推导出空气浮力修正因子。文中进行了空气浮力因子的数值模拟,通过数值模拟曲线分析出空气浮力修正因子的影响,并在曲线图上便捷的查出空气浮力修正因子,直接应用于砝码折算质量的计算。 相似文献
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材料各项测试参数的变化对其热分析结果会产生一定的影响。深入研究了金属材料的质量、颗粒尺寸、升温速率等技术参数对热分析结果中的相变温度、比焓、质量变化率等的影响。结果表明:试样质量的增加会使相变温度升高,比焓不变;试样颗粒尺寸越大,相变过程越长,比焓越大;空气环境下试样的相变更早开始与结束,比焓更小;升温速率对比焓有显著影响,升温速率越大,比焓越小。 相似文献
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对于准确度等级高的砝码在进行折算质量的不确定度评定时,要考虑空气浮力修正,如果空气浮力小于被测砝码最大允许误差的九分之一时,可不进行空气浮力修正,而将其放人空气浮力不确定度进行计算。 相似文献
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0引言用于检定砝码的电子天平如何选择?主要考虑何种技术参数?参数应满足何种要求?JJG99-2006《砝码》检定规程中规定:在测量砝码质量选择衡量仪器时,衡量仪器的计量特性在进行测量之前要已知。如果被检砝码进行空气浮力修正,则其合成标准不确定度不得超过被检砝码质量最大允许误差绝对值的六分之一;如果被检砝码不进行空气浮力修正,则合成标准不确 相似文献
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基于单晶硅球与现行常用砝码的物理特性差异,提出空气浮力修正改进计算方法.通过对硅球质量测量时空气密度瞬态变化分析,得出单次测量序列中存在6种不同空气密度变化序列,根据不同精度等级测量对各环境参数变化限值的要求,利用CIPM公式计算环境条件动态变化下的空气密度变化量,分析得出即使在恒温恒湿精密实验室下开展测量,相邻2次测... 相似文献
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针对羊毛纤维过滤材料对大气尘中颗粒物的过滤机理进行了理论分析,研究了羊毛纤维过滤材料对颗粒物的过滤效率的影响因素,并结合羊毛纤维的特殊优势,进一步探讨以羊毛纤维为基材的过滤材料净化室内空气的相关机理及其应用。 相似文献
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实现高效空气过滤器计数法的首要任务就是选择合适的气溶胶发生器。本文中首先介绍了凝聚式单分散气溶胶发生器的工作原理、构造形式、发生流程以及国内外研究进展,然后详细分析了其发生气溶胶粒子粒径和浓度的影响参数;作者认为凝聚式单分散气溶胶发生器能够快速地发生浓度可调的、适用于高效空气过滤器效率测试的单分散亚微米气溶胶粒子,可以满足国家标准《高效空气过滤器性能试验方法》的修订对气溶胶发生装置的要求。 相似文献
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首先对过滤器运行存在的问题进行了分析,结合南京某地铁站空调系统过滤器清洗前、后各个房间的风量和空气温、湿度实测结果,分析了过滤器对地铁空调系统冷量的影响.实测结果表明,当空调系统冷量减小时,对过滤器进行清洗会显著增大空调系统的风量和冷量、提高空调的换热效率、有效提高了冷量的传输,并且节能效果明显. 相似文献
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In general mass measurements are carried out in air and that’s why air buoyancy correction plays a major role in mass measurements and it is totally dependent on density of air of the laboratory during the measurement. The density of air is calculated from temperature, relative humidity, air pressure, concentration of CO2 monitored (for CIPM formula only) in the laboratory rather direct determination and for calculation of density of air, CIPM-2007 formula is recognized as most accurate formula. Since CIPM formula is very complicated formula and it is not required for less accurate measurements, different National Metrology Institutes have derived simple equations to calculate air density and those are known as approximation formulas. We had gone through a comparative analysis among different formulas of density of air to evaluate which approximation formula is most accurate compare to CIPM-2007 formula. 相似文献
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It is convenient to measure the optical attenuation A of the combination of a layer of atmospheric particulate matter and the quartz fiber filter on which it has been collected. The problem of relating A to the absorption and scattering coefficients k and s of the particulate matter itself is treated as a problem in diffuse reflectance spectroscopy using the KubelkaMunk theory. The results show that although, in general, A is a nonlinear function strongly dependent on both s and k, for a limited range of s and sample thickness d, A can be a practically linear function of k. Fortunately, this range includes that common to atmospheric particulate samples. Furthermore, it is shown that if the filter's reflectance is sufficiently high, A can be nearly independent of s. This is in agreement with experimental and, for the limiting case when the substrate filter reflectance is unity, theoretical results obtained by other researchers. Use of such measurements of A as a means of determining the black carbon mass loading C on a filter is also investigated. It is shown that when the black carbon mass fraction f(c) is high, as it is for samples collected in large urban areas, A is a predictable and practically linear function of C. However, when f(c) is low, as it is for many rural locations, then the slope of the function A(C) is strongly dependent on f(c), leading to possible overestimates of C. This problem can be alleviated by making the measurement of A at near-infrared wavelengths rather than in the visible spectrum. 相似文献
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:IGCC(整体煤气化联合循环 )、PFBC(增压流化床联合循环 )等新型、高效的能源清洁转换系统都需要一套运行可靠、高效、维护简单的高温或常温气体净化装置。本文利用光导纤维浓度测试仪对带有内置过滤元件的三维流化床实验台的流动进行了实验研究。运用FFT方法对颗粒浓度时间序列进行了大量的概率分析和统计。结果表明 ,局部颗粒浓度、L阀、卸料口的位置和气 -固混合特性对颗粒层的形成有重要影响 ,床内气固混合以低频为主 ,在距离布风板z =2 5 0mm附近颗粒浓度较高 ,混合较好 ;径向在壁面附近、边角处颗粒浓度较高 ,混合较好 相似文献
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Patrick J. Abbott Zeina J. Jabour 《Journal of research of the National Institute of Standards and Technology》2011,116(4):689-702
Vacuum weighing of mass artifacts eliminates the necessity of air buoyancy correction and its contribution to the measurement uncertainty. Vacuum weighing is also an important process in the experiments currently underway for the redefinition of the SI mass unit, the kilogram. Creating the optimum vacuum environment for mass metrology requires careful design and selection of construction materials, plumbing components, pumping, and pressure gauging technologies. We review the vacuum technology1 required for mass metrology and suggest procedures and hardware for successful and reproducible operation. 相似文献
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可吸入颗粒物采样器准确性计量检测方法的设计及研究 总被引:2,自引:0,他引:2
可吸入颗粒物(PM10)采样器(或测试仪)是进行大气中PM10监测、相关课题研究及评价室内外空气质量的主要工具,该仪器测量结果的准确性是评价其计量性能的主要指标。本文中介绍了国内外对可吸入颗粒物采样器准确性的几种检测方法,并提出了这些方法的问题与不足。为了满足计量学的溯源性要求,本文对可吸入颗粒物采样器准确性的计量检定方法进行了设计,所设计的方法是以静态试验为基础,选用球形粒子为标准粒子,滤膜称重为检测方法。在此基础上,利用该方法还进行了相关的实验研究。 相似文献