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排序方式: 共有436条查询结果,搜索用时 15 毫秒
1.
Robert J. Hoard Steven R. Holen Michael D. Glascock Hector Neff J. Michael Elam 《Journal of archaeological science》1992,19(6)
Cryptocrystalline silicates from the Chadron Formation were widely used by prehistoric human groups in the Great Plains of North America. There are two documented quarry areas: Flattop Butte in Colorado and the White River Badlands of South Dakota. Cryptocrystalline silicates from these sources are visually indistinguishable, making it difficult to determine the sources of artefacts found at archaeological sites. In this investigation, neutron activation analysis is used to distinguish the two sources. This technique also identifies lithic material from the Clovis-age Eckles site in Kansas as being from Flattop Butte. 相似文献
2.
何堂坤 《文物保护与考古科学》1990,2(2):33-38
本文通过考古实物的科学分析,认为早在西周时期胶东青铜技术便发展到了一定水平,战国后便发展到了较为成熟的阶段,大约自西周始,胶东青铜技术与中原便是大体同步发展了的.文章最后还将胶东青铜合金成分与《考工记·六齐》作了比较,并提出了“六齐”既不是生产经验的总结,也不是指导生产实践的工艺规范,而是一种试验资料的反映和归纳的观点。 相似文献
3.
This study aims to show how dispositional characters of political leaders are affected by situational developments during the time‐in‐office. Although newly emerging literature of leadership traits demonstrate that significant events alter leaders’ traits, they mainly focus on the measurement of shocking events on dispositional features, leaving the effect of achievements underexplored. The Iranian nuclear deal of 2015 is one of the most significant successes in the last decade of world politics. Gambling his political career on nuclear talks by promising the Iranian people to solve Iran's decades‐long isolation, President Hassan Rouhani played a momentous role in negotiating the deal. The Joint Comprehensive Plan of Action (JCPOA) was globally recognized as a success of Rouhani's leadership. Using the Leadership Trait Analysis (LTA), this article will show the role of Rouhani's personality in the realization of the historic nuclear deal and measure the effect of such a success on Rouhani's leadership traits. 相似文献
4.
Jürgen Mittelstraß 《Berichte zur Wissenschaftsgeschichte》1995,18(1):15-25
Galileo did not develop a systematic methodology but rather a methodical form which represents an essential part of the development of modern scientific thought. Keywords to the methodical form of Galileo's thought are: 1) The geometrization of the sciences (‘mathematization of nature’) - this refers especially to the explication of the methodological priority of a theory of measurement. 2) Argomento ex suppositione, that is, the coupling of the originally proof-theoretical distinction between analysis and synthesis to elements of a methodology of empirical science. 3) The axiomatic structure of mechanics that corresponds to the modern semantic theory conception and to constructivist conceptions of the philosophy of science. 4) A constructive (or instrumental) concept of experience, which replaces the Aristotelian concept of a phenomenal experience in the construction of physics. 相似文献
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6.
About 200 analyses have been made on late Roman and Sassanian silver objects using energy-dispersive X-ray fluorescence. This has shown that the main feature of the composition of the silver throughout the period and across the geographical area studied was towards high fineness (average silver percentage about 95%). Compositional differences are found between Roman and Sassanian silversmiths' products for the elements copper and lead. Much of the material analysed came from hoards, and using a statistical technique on the analytical data (Discriminant Analysis) broad compositional differences between hoards were found to emerge. The use of different compositions of silver for different joined parts of a single object are discussed. 相似文献
7.
The Evolution of the Vitruvian Recipes over 500 Years of Floor‐Making Techniques: The Case Studies of the Domus delle Bestie Ferite and the Domus di Tito Macro (Aquileia,Italy) 下载免费PDF全文
The paper reports the results of a research project aimed at the characterization of the floor bedding mortars of two Roman houses in Aquileia (north‐eastern Italy), the Domus delle Bestie Ferite and the Domus di Tito Macro. Seventy floor bedding mortars of the two domus were selected and almost half were fully minero‐petrographically characterized by means of optical microscopy operated in transmitted light (OM‐TL), X‐ray powder diffraction analyses coupled with quantitative phase analysis by means of the Rietveld method (XRPD‐QPA) and scanning electron microscopy with EDS microanalysis (SEM–EDS). The results indicate an evolution of the mortar preparation techniques over time in the mosaic of both houses. The materials are compared to the traditional Roman recipes for specific construction techniques. 相似文献
8.
Omid Esmaili Lisa Grant Ludwig Farzin Zareian 《Journal of Earthquake Engineering》2018,22(9):1569-1589
We describe the formulation and application of an integrated general regional seismic loss assessment (RSLA) method for buildings in seismic regions. An efficient method for RSLA is valuable for engineers involved in city planning, risk management, and insurance dealings. In contrast to previously reported methods, the framework presented herein is hazard-based and utilizes a regional rapid seismic hazard deaggregation tool that allows regional assessment to be conducted more efficiently. The proposed technique is implemented as an example to assess general regional seismic loss in Los Angeles County for a ground motion hazard with 10% probability of exceedance in 50 years. 相似文献
9.
A simplified model useful for assessing economic losses due to moderate seismicity events in urban areas has been developed by studying the behavior of buildings before yielding their structural system, allowing for nonuniform stiffness along their height. In particular, buildings are modeled as cantilever shear beams with uniform mass and parabolic reduction of lateral stiffness. This particular stiffness distribution is relevant, as it could be expected to occur in buildings where earthquake action is a critical structural design criterion. The equation of motion governing the dynamic behavior of the proposed model is solved analytically, finding mode shapes in terms of first and second zero-order Legendre functions. The solution is verified by comparing it with results obtained from fine mesh finite element models. The effect of reducing the lateral stiffness is then studied in the first five modes of vibration. Results include modal periods, mode shapes, modal participation factors, and derivatives of mode shapes. In general, it is found that effects of reduction of lateral stiffness in mode shapes are moderate when the lateral stiffness in the free end is smaller than about seventy percent of the lateral stiffness at the fixed end, but become significant for larger reductions. Effects are particularly important for the derivative of the mode shapes, which could play a significant role in estimating interstory drift demands in buildings. Model usefulness is showcased by analyzing a test case where both acceleration and drift demands are assessed by considering uniform beams and beams with parabolic stiffness variation, finding notable improvements by considering the latter. 相似文献
10.
Shape memory alloys (SMA) can substantially improve the damping capacity and re-centering capability of elastomeric isolators. The objective of this study is to assess the seismic performance of smart lead rubber bearings (LRBs) equipped with double cross ferrous SMA wires. Hysteretic shear response of SMA wire-based LRB is determined using finite element method. The seismic response of a multispan continuous steel girder bridge isolated by SMA-LRB is evaluated. Hybrid SMA-LRB bearing exhibits a significantly lower shear strain demand (up to 46% reduction) and a higher energy dissipation capacity (up to 31% increase) compared to the LRB. 相似文献