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。     

Inca builders at Machu Picchu National Archaeological Park

Knowledge about the Inca measurement system is based on information from the colonial chronicles and modern studies of the 16th-century Quechua dictionaries. Based on those texts, we can presume that the Incas used an anthropometric system of measurement adopted from the proportions of the human body. Using cosine quantogram analysis and statistical verification, it is possible to verify the existence of the measurement system used by the Inca architects. For this purpose, a measurement series of architectural and water infrastructure elements were collected from 3D point cloud of the Chachabamba and Machu Picchu settlements in Machupicchu National Archaeological Park.     

A missing link? Network analysis as an empirical approach for critical physical geography

Critical physical geography (CPG) calls for integrative research on material landscapes and the socio-political dynamics of scientific knowledge production. Network analysis, a rich tradition of tools and approaches for analyzing relational information, has seen little use in the CPG literature to date. This represents a fruitful opportunity, as many of CPG's core interests—knowledge politics, histories of scientific concepts, and ecosocial relations—can be effectively analyzed using network techniques. In this article, I argue for adapting network approaches to CPG. First, I provide an overview of various network concepts, approaches, and their origins. I then discuss bibliometric network techniques for “science mapping” including co-word, co-authorship, and citation analyses. Next, I describe discourse network analysis, a recent mixed-method approach from political science. Finally, I discuss overlaps with emerging approaches from qualitative and visual network analysis. In each section, I provide existing and hypothetical examples, as well as software and visualization techniques, that demonstrate how network approaches could add new insights to CPG and related scholarship. Linking CPG with the diverse traditions of network analysis has the potential to produce new empirical understandings and bring the field into conversation with a growing body of research that spans the social sciences, natural sciences, and humanities.     

TEMPORAL and SPATIAL VARIABILITY OF CANADIAN INVENTIVE COMPANIES and THEIR INVENTIONS: AN ISSUE OF OWNERSHIP

Inventing is an important prerequisite for industrial economies to remain technologically competitive. Yet it is not well known how inventive companies of domestic or foreign ownership can affect a nation's technological base and, ultimately, its spatial-economic system. The present study examines this relationship in Canada by investigating the performance of its indigenous and foreign-owned inventive companies at the national, subnational, and urban levels. The results indicate that: (1) Canada's indigenous inventive companies are distinct from their foreign-owned counterparts in that they are generally smaller, are more apt to have teams of inventors, are more likely to develop product inventions, have come to manage a greater share of this nation's inventions, and are increasing their role in key Canadian industries; and (2) geographically, Canada's two largest cities and its core region were adversely affected by the declining inventiveness of American-controlled companies during the 1980s. L'esprit ?invention est une nécessité pour que les économies industrielles restent en conditions de concurrence technologique. Cependant, on connaît très peu de la manière que les entreprises inventives de propriété domestique ou étrangère affectent la base technologique ?un pays et, enfin, affectent son système spatio-écono-mique. La présente étude considère ces rapports au Canada au niveau national, sous-national et local, en exminant les performances des entreprises inventives indigènes et étrangères. Les résultats indiquent (1) qu'au Canada les entreprises indigènes et inventives diffèrent de leurs analogues étrangers: en général elles sont plus petites, ont plus tendance à consister en équipes ?inven-teurs, sont plus susceptibles de développer les inventions produites, produisent une plus grande part des inventions canadiennes, et sont en train ?augmenter leur rôle dans les industries canadiennes; et (2) que le déclin de ?esprit ?invention dans les entreprises dirigées par les américains a affecté défavorablement les deux villes les plus grandes au Canada, ainsi que la partie centrale du pays, pendant les années 1980. Mots-clés: invention, Canada, propriétéétrangère, technologie, produit     

Assessing Surface Correspondence and Trade of Maya Figurines and Moulds Using Multi‐Stripe Laser Technology and Metrology*

One of the most intriguing questions for archaeologists studying clay artefacts concerns technologies employed in their manufacture and whether standardization can be demonstrated through traditional ceramic analysis. Visual comparisons and mechanical measurements have been used to determine correlations and infer standardization. Using a laser multi‐line scanner and software developed to quantify Hausdorff distances between vertices in 3D surfaces, we analysed sample collections of figurines and moulds from Belize, Mexico and Honduras. The results indicated that this procedure was a more precise indicator of common source and standardization in moulded clay artefacts. This method provided data relevant to assessing the scope of ancient trade networks and the nature of social and economic relationships that existed among the ancient inhabitants of Mesoamerica.     

Fostering place-based innovation and internationalization – the new turn in German technology policy

Since the mid-1990s German technology policy has experienced a paradigmatic shift from standard grant schemes towards a region-oriented and competition-based R&D policy. Currently, a new policy experiment, the InterClust contest, is under way, trying to simultaneously foster place-based innovation, R&D internationalization and the internationalization of innovative places. The current paper analyses the new policy, relating it to the recent literatures on heterogeneous firms and on cluster-life cycles, and presents results from a firm survey performed in 21 winner regions of InterClust. Findings show that the new funding scheme takes insights from recent theoretical developments into account and addresses important impediments to firm and cluster internationalization. Although it is too early for an overall assessment, it is argued that the long-term impact will critically depend on the inflow of heterogeneous knowledge and the strength of intra-regional mobilization effects.     

桂平博物馆馆藏东汉双耳铜甑铸造工艺及其保护修复研究

广西桂平博物馆藏东汉铜甑对于研究广西地区青铜器冶铸技术的发展具有重要的研究价值。但器物长期保存于潮湿环境中,矿化严重、保存状况较差,亟须保护修复。本研究应用X射线影像观察、金相显微镜、扫描电镜及能谱分析、模拟实验验证等方法研究了器物的铸造工艺、合金成分以及锈蚀产物成分。结果表明该器物为整体铸造成形,器物铸造时使用了轮制技术、刮板造型工艺以及铸后刻纹的工艺,箅部范块制作过程是用器身模翻制器身范后脱模,将器身模的圈足部分切下,然后在圈足泥模上刻出箅部型腔。在此基础上,遵循最低限度干预原则,力求将传统的文物修复手段与现代修复理念相结合,通过除锈、修补等保护修复措施后,不但提高了器物的整体稳定性,而且达到了可以展陈,发掘文物潜在价值的要求。     

Assessment and Significance of a World War II battle site: recording the USS Emmons using a High‐Resolution DEM combining Multibeam Bathymetry and SfM Photogrammetry

The USS Emmons, a 106m US Navy Gleaves‐class destroyer minesweeper that sank in 40m of water off Okinawa Island, Japan after kamikaze attack in 1945, is used as a case study for examining the history, multivocal significance, and heritage management of a World War II naval battle site. A baseline record of the site was made using an innovative method incorporating precise control points obtained from high‐resolution multibeam echosounding bathymetry to generate 3D models using structure‐from‐motion photogrammetry. The 3D models produced can be used for sharing information about this underwater cultural heritage and for future in situ monitoring of the archaeological remains.     

Restoration of paintings on domes with non-developable geometry (Los Santos Juanes Church in Valencia)

The restoration of paintings on elements in cultural heritage buildings (fundamentally, churches) involves two structural problems: capturing the geometry of the construction element and its development. In many cases, the geometries are regular (e.g., cylinders, spheres, elliptical domes). However, there are cases in which the elements cannot be adapted to any known geometry, much less one that can be mathematically developed. The development of surfaces becomes essential for the restoration of paintings over “flat elements” (over which work is performed on the ground) that are subsequently transferred to the real surface (ceilings). The mathematical transformations that allow regular geometries to be developed are widely known (cartographic projections). However, when the geometry is irregular, there is no development. This study presents a new methodology based on differential rectification and its application for the development of oculi in the Los Santos Juanes Church (Valencia), whose geometry is completely irregular both in shape and as a result of construction defects (and damage caused by fire). The present study focuses on the restoration of paintings damaged by fire.