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.     

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.     

Improvements in Archaeomagnetic Dating in Western Europe from the Late Bronze to the Late Iron Ages: An Alternative to the Problem of the Hallstattian Radiocarbon Plateau

We present a new curve of the directional secular variation of the geomagnetic field in Western Europe between 1500 bce and 200 ce . Its computation relies on a Bayesian framework. The fast secular variation during the Late Bronze and Early Iron Ages makes archaeomagnetic dating efficient with a respective precision of 150–200 and 60–100 years during these periods. The Bayesian method also provides posterior date distributions that refine the dating of reference data, especially during the period of the Hallstattian radiocarbon plateau. Archaeomagnetism becomes a valuable alternative to radiocarbon and will help to improve the archaeological chronologies.     

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.     

Modelling Resource Values and Climate Change Impacts to Set Preservation and Research Priorities

ABSTRACT

Climate change impacts will increase in their frequency and severity in the coming decades, resulting in compromised integrity or destruction of thousands of heritage resources. Efforts are needed to identify, record, and study resources that will be affected. To set research and preservation priorities, the vulnerability of resources to climate change impacts and their importance to scientific research, preservation, and other resource values needs to be understood. We advocate a modelling approach which predicts the location, timing, and severity of climate change impacts; identifies resources at risk, their resource values, and opportunity costs; and prioritises research and preservation options based on these assessments. The need for this approach is illustrated with examples from two coastal areas subject to different impacts and hosting different types of heritage resources: the Atlantic coast of Georgia in the United States and the Wismar Bight along the Baltic Sea in northern Germany.     

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.     

Spatial optimisation of fire service coverage: a case study of Brisbane,Australia

In the context of changing demand for fire services, spatial optimisation of fire coverage has attracted little scholarly attention despite its potential to improve emergency response and to inform future service planning for fire stations. Drawing on small area population forecasts, this paper extends the application of the Maximum Coverage Location Model to compute and delineate the spatial coverage of current and proposed new fire stations to align with population growth estimates for Brisbane, Australia. Our results reveal important gaps in fire cover that are likely to emerge as a result of predicted population growth, the spatial patterns of which varies across the Brisbane metropolitan area. We draw on these results to delineate a series of new potential sites for fire stations to ameliorate the reduction in spatial coverage as a consequence of predicted population growth demonstrating the utility of our analytic approach for decision‐making and operational planning in the fire services.     

Food for all: An agent-based model to explore the emergence and implications of cooperation for food storage

Abstract

A consistent access to food is paramount for humans at individual and group level. Besides providing the basic nutritional needs, access to food defines social structures and has stimulated innovation in food procurement, processing and storage. We focus on the social aspects of food storage, namely the role of cooperation for the emergence and maintenance of common stocks. Cooperative food stocks are examined here as a type of common-pool resource, where appropriators must cooperate to avoid shortage (i.e. the tragedy of commons). ‘Food for all’ is an agent-based model in which agents face the social dilemma of whether or not to store in a cooperative stock, adapting their strategies through a simple reinforcement learning mechanism. The model provides insights on the evolution of cooperation in terms of storage efficiency and considering the presence of social norms that regulate reciprocity. For cooperative food storage to emerge and be maintained, a significant dependency on the stored food and some degree of external pressure are needed. In fact, cooperative food storage emerges as the best performing strategy when facing environmental stress. Likewise, an intermediate control over reciprocity favours cooperation for food storage, suggesting that concepts of closed reciprocity are precursors to cooperative stocks, while excess control over reciprocity is detrimental for such institution.     

Learning to teach geography for primary education: results of an experimental programme

Students training to become primary school teachers appear to have little awareness of the core concepts of geography (teaching). To ensure that future primary school teachers are able to develop their pupils’ geographical awareness, a six weeks programme was developed. The characteristics of this programme – named Consciously Teaching Geography (CTG) – are: principles of good geography teaching, conjunction and a recurrent structure during training, modelling and reflection. In a quasi-experimental research design the question is answered what the effects are of CTG on the development of pedagogical content knowledge (PCK) for the subject of geography of first year primary student teachers. The results indicated that the programme has a positive effect on the domain-specific PCK development in the short term.