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。     

Exchange on the quantitative measurement of ethnic and national identity*

In recent decades, there has been a noticeable increase in the use of quantitative techniques in the study of ethnicity and nationalism, without, however, a sufficient amount of reflection on how these techniques have contributed to our understanding of ethnic and national identities. As such, in this exchange three sets of authors answer questions about the degree to which it is possible to use quantitative data to measure ethnic and national identities, which types of methods are most suitable in measuring these identities and what the major research findings of this quantitative research are that were not possible using qualitative approaches.     

基于GIS的沈阳旧城区叙事空间研究

20世纪60年代,叙事学作为一门学科始于西方历史学、文学领域。直至20世纪末,叙事学开始转向空间领域研究形成空间叙事学,并被逐步应用到城乡规划中,尤其是城乡空间结构等领域。空间叙事学不仅关注城市发展中的物化要素,更加注重物化要素所代表的城市文化和城市记忆等非物化要素的深入挖掘,是探究场所本体与场所精神的重要研究思路。本文从空间叙事学出发,基于GIS平台运用核密度及K函数对古代、近代、现代三个时期沈阳旧城区人工叙事要素和人文事件叙事要素进行点模式量化分析,得出沈阳旧城区叙事空间的总体结构,以及叙事点核、叙事廊道、叙事簇群等叙事空间结构单元,指出沈阳旧城区叙事空间的动态发展性、功能多样性和历史传承性特点,探讨了叙事空间的经济驱动、自然要素、城市定位和交通发展四大演变机制。从人文地理学的视角出发,结合叙事空间理论对沈阳旧城区叙事空间进行分析,结果具有文化地理和城市地理双重属性,丰富了城市研究在该视角下的研究成果。     

考释胡适的两封书信

本文考证了胡适致任鸿隽、胡近仁两封信的写作时间,纠正了以往的误判。将信件的内容置于广阔的历史背景下加以考察,并与相关史料参考互证,不仅有助于考察信件的写作时间,且有助于理解信函的真实含义。     

Quantitative analysis of two low-cost aerial photography platforms: A case study of the site of Zagora,Andros, Greece

Aerial photography provides a valuable recording method for archaeological sites and is often underutilized. In the past, aerial photographic platforms were expensive and often required highly specialized equipment. However, with new technology a variety of different platforms are now available. This paper will analyze two low cost aerial photographic platforms used at the Australian Archaeological Institute at Athens/University of Sydney's project at Zagora, on the island of Andros, Greece. Over two years, both kites and drones were used with relative success. Through a review of the application of both systems on the project, along with a quantitative analysis of the cost, transportability, operation and quality of photographs, the strengths and weaknesses of both platforms will be discussed.     

多种科技方法在古月桥勘察修缮设计中的应用

建于南宋嘉定六年(公元1213年),位于浙江省义乌市的古月桥是折边拱桥这种桥梁发展过渡形式中不可多见的典型实证,具有极高的历史、科学、艺术、文化和社会价值。为了明确古月桥目前的状态,分析其主要威胁及病害原因,判断结构稳定性,进而制定有针对性的修缮方案,采用多种科技方法对古月桥进行了勘察和综合判断。面对桥身残破的现状,工作组采取了三维激光扫描、微观实验、结构分析等多种科技方法综合勘察,不仅较为清晰的地了解了古月桥的病害威胁,也分析了其背后致因及相互之间的联系;最终对古月桥稳定性及保存状况做出了综合判断。上述多种方法的应用,不仅相互印证了勘察结论,也为后续保护工作提供了重要的依据。     

Quantifying artefacts over time: Interval estimation of a Poisson distribution using the Jeffreys prior

This paper presents a new method for estimating the amount of an artefact class in use at a given moment in the past from a random assemblage of archaeological finds. The method is based on the use of simulation, since an analytical solution is computationally impractical. Estimating the number of artefacts in use at any time t is shown to follow a Poisson distribution, which allows for credible intervals to be established using the Jeffreys prior. This estimator works from minimal assumptions about the dating and duration of finds, as well as the intensity of collection, and is applied to coinage from four Roman‐period sites excavated by the Roman Peasant Project (2009–14). The result provides an estimation of the abundance of material according to an interval of certainty.     

Hybrid finite element–finite volume discretization of complex geologic structures and a new simulation workflow demonstrated on fractured rocks

The generation of computational meshes of complex geological objects is a challenge: their shape needs to be retained, resolution has to adapt to local detail, and variations of material properties in the objects have to be represented. Also mesh refinement and adaptation must be sufficient to resolve variations in the computed variable(s). Here, we present an unstructured hybrid finite element, node‐centred finite‐volume discretization suitable for solving fluid flow, reactive transport, and mechanical partial differential equations on a complex geometry with inhomogeneous material domains. We show that resulting meshes accurately capture free‐form material interfaces as defined by non‐uniform rational B‐spline curves and surfaces. The mesh discretization error is analysed for the elliptic pressure equation and an error metric is introduced to guide mesh refinement. Finite elements and finite volumes are represented in parametric space and integrations are conducted numerically. Subsequently, integral properties are mapped to physical space using Jacobian transformations. This method even retains its validity when the mesh is deformed. The resulting generic formulation is demonstrated for a transport calculation performed on a complex discrete fracture model.     

The Origin and Archaeometallurgy of a Mixed Sulphide Ore for Copper Production on the Island of Kea,Aegean Sea,Greece

At the hill of Agios Symeon, on the island of Kea, Aegean Sea, Greece, ancient metallurgical slags with a high Pb–Zn–Cu content have been found. Thermodynamic simulations have been carried out, using the FactSage? thermodynamic database computing system, with a view to understanding the ancient metallurgical processes that produced the observed slag compositions and morphologies. The simulations demonstrate that the slag samples resulted from Cu‐making processes. It would thus appear that mixed ores were used, containing Cu₂S–FeS–PbS with significant amounts of sphalerite (ZnS) as impurity. The roasted ores were reduced at relatively high oxygen potentials at ～1125°C to form Cu containing low levels of Pb, Fe and Zn.     

The Unflinching Mr. Smith and the Nuclear Age**

This article focuses on the U.S. diplomat and nuclear arms control negotiator Gerald (Gerry) Coat Smith in order to cast new light on the importance of diplomats in the context of the set of international activities currently labelled as “science diplomacy.” Smith, a lawyer by training, was a key negotiator in many international agreements on post-WW2 atomic energy projects, from those on uranium prospecting and mining, to reactors technologies to later ones on non-proliferation and disarmament. His career in science (nuclear) diplomacy also epitomized the shortcomings of efforts to align other countries’ posture on nuclear affairs to U.S. wishes. In particular, the unswerving diplomat increasingly understood that strong-arm tactics to dissuade other countries from acquiring nuclear weapons would not limit proliferation. Not only did this inform later U.S. diplomacy approaches, but it lent itself to the ascendancy of the new notion of “soft power” as critical to the re-definition of international affairs.