Strontium isotope analysis in ancient glass from South Asia using portable laser ablation sampling

In order to carry out strontium (Sr) isotope analysis, glass artefacts from South Asia were sampled with portable laser ablation (pLA), a relatively novel sampling technique that leaves damage invisible to the naked eye. Subsequently, thermal ionization mass spectrometry (TIMS) was used to obtain Sr isotope ratios after sample dissolution and separation. In this study, the goal was twofold: to determine whether the measurements of Sr isotope ratios were impacted by using a portable laser as a sample tool; and to assess the pertinence of using Sr isotope ratios to provenance Indian glass. Despite a deterioration in the precision of the measurement of the Sr isotope ratios for artefacts sampled with pLA compared with the traditional sampling method, the Sr isotope ratios of certain Indian glass are so different that this does not affect their separation but a comparison of data sets obtained using standard methods and pLA might be challenging.     

Anticipating the Next Half‐Century of Geographical Analysis

Prompted by a series of panel sessions at a recent American Association of Geographers annual meeting entitled “A Globe‐Shaped Crystal Ball: The Next Fifty Years of Geographical Analysis,” participants were asked to speculate on the future of the journal, which of course has broader implications for spatial and geographic analytics. In what follows, I provide my thoughts on the journal as a reader, contributor, referee, and former editor of Geographical Analysis. The major points touched upon include the following. First, application to address substantive concerns will come to dominate the field. Second, the spatial data deluge will continue unabated, but will lead to important advances because of better detail and less abstraction of reality. Third, analytical methods will evolve specifically for big data. Fourth, the point‐and‐click revolution will result in ever more use of spatial analytics, but also will lend itself to greater and more widespread abuse of these methods. Fifth, addressing assumptions and theoretical foundations of long utilized approaches will revolutionize a new generation of spatial analytics. Sixth, geographic uncertainty and bias will be more than an afterthought, and methods will emerge to support meaningful analysis. Finally, spatial optimization will have increased prominence in fundamental analysis, particularly associated with establishing and evaluating significance.     

基于三维扫描模型的兵马俑足踝有限元分析

利用三维扫描技术获取兵马俑残片的三维点云数据,结合Geomagic Studio和Hypermesh建立高精度的兵马俑足踝残片三维实体网格模型。通过基于ABAQUS的重力作用下的有限元分析,研究足踝部分的Von Mises应力和变形特征,以确定足踝处的受力薄弱部位。为进一步探究模型各残片的最佳点云简化比例,采用点云简化模型进行相同工况的有限元分析,以验证点云简化的可靠性。结果表明:结构在重力作用下可保持安全稳定的状态,相对薄弱部位位于左腿足踝处;对于大部分残片,其最佳简化比例在60%～70%,简化后可有效缩短模型实体化处理时间;采用简化模型得到的有限元结果,其最大Mises应力相比于原始模型的误差小于15%,且应力云图和变形图形状接近,模型简化具有可靠性。     

一种油画颜料层裂纹的修复技术分析

油画颜料层裂纹是一种常见的病害类型,严重的裂纹会影响作品的视觉效果。裂纹修复所采取的措施应以缓解病害,延续寿命为目标,避免不当修复对其文物价值的改变。本研究通过红外光谱和便携式X荧光能谱分析,初步确定了裂纹产生的原因与材料技法和机械作用力有关,长期的温湿度波动则是最终形成老化裂纹的重要因素。对两类常见的裂纹加固方法比较后得出结论,色蜡改变了原画的光泽度和肌理层,动物胶调碳酸钙更适宜作为裂纹的填补材料。观察修复后的油画保存状况,发现经过修复的颜料层仍存在继续劣化的风险,必须维持保存环境的相对稳定,方可延长修复周期。     

A STUDY OF CHINESE PORCELAIN RAW MATERIALS FOR DING,XING, GONGXIAN AND DEHUA WARES*

The raw material used largely determines the type and quality of porcelain produced. Twenty-three raw materials used for making Ding, Xing, Gongxian and Dehua porcelain bodies were studied using principal component analysis. Results show that for Dehua wares, only one raw material was used. For Ding wares, although there were many possible raw materials, the use of one alone is unlikely. Lingshan clay was the main raw material but it has to be mixed with other raw materials: Pinjiawa clay, quartz, feldspar and dolomite. The Xing pieces can be divided into three groups and Gongxian wares into two groups, which are discussed in detail.     

Nestorian Crosses from Jabal Berri

Two small crosses, one of bronze and the other of mother-of-pearl, from the surface of a site near Jabal Berri in northeastern Saudi Arabia are presented. They are attributed to the Nestorian community of Bet Qatraye which is known from literary sources to have flourished during the Sasanian period.     

The A-Bomb Controversy at the National Air and Space Museum

Born in Boston, Massachusetts, in 1947, Linenthal earned his bachelor's degree in religious studies at Western Michigan University, his master's degree in divinity at the Pacific School of Religion, and his Ph.D. in religious studies at the University of California, Santa Barbara. He is Professor of Religion and American Culture at the University of Wisconsin, Oshkosh. His books include: Symbolic Defense: The Cultural Significance of the Strategic Defense Initiative (1989); Sacred Ground: Americans and their Battlefields (2nd edition, 1993); Preserving Memory: The Struggle to Create America's Holocaust Museum (1995); American Sacred Space (co-editor, 1995). He is writing a history of the A-Bomb controversy that will appear in a book to be published in 1996. Linenthal has often lectured about controversial historic sites for National Park Service staff. At the USS Arizona Memorial, Linenthal delivered a commemorative address on 7 December 1994, on the 53rd anniversary of the attack on Pearl Harbor. Linenthal and his wife, with their two sons, reside in Oshkosh, Wisconsin. Linenthal was the only historian to testify before the Senate Committee on Rules and Administration about the National Air and Space Museum's ill-fated exhibit, “The Last Act: The Atomic Bomb and the End of World War II.” What follows is Linenthal's Senate statement and comments he has written for The Historian.