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1.
Bast fibres have been commonly used as a textile material in Northern Europe since Neolithic times. However, the process of identifying the different species has been problematic, and many important questions related to their cultural history are still unanswered. For example, a modified Herzog test and the presence of calcium oxalate crystals have both been used in identification. In order to generate more reliable results, further research and advancement in multi-methodological methods is required. This paper introduces a combination of methods which can be used to identify and distinguish flax (Linum usitatissimum), hemp (Cannabis sativa), and stinging nettle (Urtica dioica). The research material consisted of reference fibres and 25 fibre samples obtained from 12 textiles assumed to be made of nettle. The textiles were from the Finno-Ugric and Historical Collections of The National Museum of Finland. The fibre samples were studied by observing the surface characteristics and cross sections with transmitted light microscopy, and by using a modified Herzog test with polarized light, in order to identify the distinguishable features in their morphological structures. The study showed that five out of 25 samples were cotton, 16 nettle, one flax, and one hemp. Findings from two samples were inconsistent. The results show that it is possible to distinguish common north European bast fibres from each other by using a combination of microscopic methods. Furthermore, by utilizing these combined methods, new and more reliable information could be obtained from historical ethnographic textiles, which creates new vistas for the interpretation of their cultural history. 相似文献
2.
文章简单介绍了特征模式方法,该方法为任意形状的电磁物体定义了一系列正交的特征电流。这些特征电流是该电磁物体本身的固有属性,因此可以从本质上解释其辐射特性。文章利用特征模式方法提取不同形式贴片天线的主要特征电流,通过对比研究得到不同形状贴片天线上特征电流的一般性规律。 相似文献
3.
Fadia Dakka 《British Journal of Sociology of Education》2020,41(1):80-94
AbstractThis article explores the powerful yet contradictory role of neoliberalism, its competitive mechanisms and emotional logics. Theoretically, it reviews the shifting state-higher education-market nexus through the lens of a critical cultural political economy paradigm. Conceptually, it closely examines Davies’ work on the ‘logic of competition’ (2014) and Naidoo’s idea of ‘competition fetish’ (2011, 2015, 2018) to expose the material and discursive dispositifs through which nation-states, institutions and individual actors mobilize universities to position themselves in the global knowledge economy. The discussion is informed and supported by empirical evidence drawn from a doctoral project (2013–2014). The article aims to contribute to the extant critique of (higher) education by introducing the paradox of ‘polarized convergence’ as an instance of differentiation without diversity in the contemporary English university. Such paradox urges the re-visitation and broadening of the idea and practice of the entrepreneurial university to reinvigorate the link between competition, innovation and diversity. 相似文献
4.
利用二向光度计实测了4个物候期杨树单叶的偏振反射比与二向反射比数据,并对此数据进行了分析,得出了杨树单叶的偏振反射特征与二向反射特征之间的关系及其对物候变化的响应,为偏振光遥感、多角度遥感的深入研究与应用提供了依据,并且对森林遥感也做出了一种新的尝试. 相似文献
5.
全内反射时由于表面波的存在,直接影响傅科棱镜出射偏振光的纯度。本文提出为了获得高纯度的偏振光,利用消光比的大小来选择空气层厚度的方法。 相似文献
6.
皈依基督后的北村置身神界看人界,努力在关注现实人生意义和价值的追问探寻中,突出基督对于处在精神绝境中的人的拯救。在当代语境中,为了确立这种神圣话语,北村在他的小说叙事中往往采取了一种极端表达的叙事策略。 相似文献
7.
Characteristics of a single-feed dual-frequency bow-tie microstrip antenna are studied. By using the variation method, simple formulas for resonant frequencies of the bow-tie microstrip antenna are derived. It is shown that the dual-frequency ratio can be controlled easily by choosing the parameters of the antenna. This design gives compact antenna size and simple antenna structure. Experimental results are presented, verifying the validity of the design. 相似文献
8.
蒋学华 《临沂师范学院学报》2003,25(3):26-28
基于电流变液悬浮颗粒在外电场作用下的极化模型，采用柱子近程相互作用近似，研究了固化条件下颗粒形成不同结构时相互作用能的大小，及颗粒形状对相互作用能的影响，分析了电流变液固化时可能形成的颗粒结构． 相似文献
9.
用菲涅耳公式讨论介质界面反射与折射对光的偏振态的影响，引入光线坐标系，详细分析了单色线偏振光经界面反射后光的方位角的改变规律及全反射后的偏振态；简述了部分偏振光、椭圆（圆）偏振光经界面反射后偏振态的变化。 相似文献
10.
本文首先推导出圆极化光波对原子波包平均作用力的一般表达式,然后以高斯波包为例计算了其所受的平均作用力,用计算机绘出了它随时间变化的曲线,并对该平均作用力做了详细的讨论。 相似文献