Modeling the prehistoric arrival of the sweet potato in Polynesia

The sweet potato is a plant native to the Americas, and its pre-historic presence in Polynesia is a long-standing anthropological problem. Here we use computer-driven drift simulations to model the trajectories of vessels and seed pods departing from a segment of coast between Mexico and Chile. The experiments demonstrate that accidental drift voyages could have been the mechanism responsible for the pre-historic introduction of the sweet potato from the Americas to Polynesia. While present results do not relate to the feasibility of a transfer by purposeful navigation, they do indicate that this type of voyaging is not required in order to explain the introduction of the crop into Polynesia. The relatively high probability of occurrence and relatively short crossing times of trips from Northern Chile and Peru into the Marquesas, Tuamotu and Society groups are in agreement with the general consensus that this region encompasses the area of original arrival and subsequent dispersal of the sweet potato in Polynesia.     

Computer programmes for the correction of matrix effects in the XRF analysis of glass,ceramics and related silicate systems

The quantitative analysis of glass, ceramics and related silicate systems by means of energy dispersive X-ray fluorescence spectrometry is considered and problems arising from the selective absorption of X-rays in multi-element specimens are discussed. A computer programme written in FORTRAN and based upon a “semi-fundamental parameters” approach to the correction of matrix effects in glass and chemically similar materials is fully described. Model data are provided to enable the programme to be run and tested. An “empirical coefficients” computer programme for the quantitative analysis of silicate systems is outlined and the limitations of this type of programme are pointed out. The importance of adequate sample preparation prior to X-ray spectrometric analysis is stressed.     

文物计算机辅助修复方法探讨

为提高文物的修复效率和修复质量,改变传统以人工技艺为主的修复方法,探讨利用计算机辅助文物修复方法。通过图像处理研究计算机辅助文物修复的设计方法,研究包括文物破损边界特征的数据提取,实现文物修复模型的生成、修复方案结构设计优化。以吴虎鼎为应用案例进行了试验。研究结果表明,计算机辅助修复可以缩短文物修复周期、提高文物修复质量。     

基于视觉的明清古家具数字文化档案高精度三维重建

文物是人类在社会活动中遗留的具有历史、艺术、科学价值的遗物和遗迹。优秀物质文化遗产的体系庞大、内容繁杂,数字化三维重建是保存、管理文物的一种切实可行的方案,对文化传承意义深远。相比于三维激光扫描、结构光技术等在成本和效率方面都有待改进的现有方法,数字近景摄影测量在确保低成本、高效率的同时,还能够满足数据的精度要求和详细程度。如何应用摄影测量技术对文物进行高效三维重建,实现纹理、部件、结构的精细化描述,并综合管理文物以便线上欣赏、未来修复与辅助断代,对优秀物质文化遗产的保护与传承至关重要。 本研究提出了基于视觉的三维建模方案,分为明清家具分层管理体系构建、高效率数据采集与精细化三维重建、高精度三维数字文化档案建设三步。首先针对明清家具的文化特点,从类别、纹饰、部件出发进行分层分类管理,构建独特编码体系;其次基于数字近景摄影测量技术,提出了对明清家具进行非接触数据采集的低成本高效率方法,进行高精度三维重建;再次从三维信息中提取家具纹饰、部件、结构特征,以编码为依据建立索引,为三维数字文化档案的建设提供信息基础;最后设计分层索引结构,建设高精度数字文化档案,搭建互联网共享平台进行展示。 以100套明清古家具袖珍模型为实例进行精细化数字建模,基于数字近景摄影测量技术,将模型精度控制在毫米级别,完成了文物要素提取、分类体系搭建、属性信息管理与索引结构设计,构建了历史文化和三维模型融合的数字文化档案。研究结果表明,基于视觉的非接触视觉处理算法能够实现高精度三维重建,提出的技术方案能够保留模型的细节程度,并且降低了成本、提升了效率,对文物类别、部件、纹饰的属性管理与索引架构能有效管理文化信息,数字文化档案兼具科技、人文与传统美学,满足文物保护需求。明清家具三维数字文化档案可用于古家具的研究,有利于中国古代家具工艺的传承,而其中对于家具的历史年代的介绍鉴别能够辅助断代。下一步将考虑运用人工智能对家具纹饰和部件进行元素组合,生成个性化定制家具。同时将完善技术方案,应用范围拓展至小型文物,支撑数字博物馆建设。     

Neuromyelitis optica: Application of computer diagnostics to historical case reports

The retrospective diagnosis of illnesses by medical historians can often be difficult and prone to bias, although knowledge of the medical disorders of historical figures is key to the understanding of their behavior and reactions. The recent application of computer diagnostics to historical figures allows an objective differential diagnosis to be accomplished. Taking an example from clinical neurology, we analyzed the earliest reported cases of Devic’s disease (neuromyelitis optica) that commonly affects the optic nerve and spinal cord and was previously often confused with multiple sclerosis. We conclude that in most identified cases the software concurred with the contemporary physicians’ interpretation, but some claimed cases either had insufficient data to provide a diagnosis or other possible diagnoses were suggested that had not been considered. Computational methods may, therefore, help historians to diagnose the ailments of historical figures with greater objectivity.     

Bighorn hunting,resource depression,and rock art in the Coso Range,eastern California: a computer simulation model

The extraordinary record of prehistoric rock art depicting tens of thousands of animal images in the Coso Range of eastern California provides an opportunity to study the relationship between aboriginal hunting, forager ecology, bighorn prey population levels, and the production of rock art. We review archaeofaunal evidence that the Coso desert bighorn sheep population was strongly depleted during the Newberry era after 1500 B.C. We discuss the dating of the rock art and show a correlation between bighorn depletion and increased rock art production. These data are consistent with the arrival of Numic foragers ca. A.D. 600 who competed with the Coso Pre-Numics and eventually terminated the Coso rock art tradition. An ecological predator-prey computer simulation of the human populations (Numic and Pre-Numics), the sheep population, and the rock art “population”, demonstrates these proposed interconnections and gives a reasonable fit to the observed rock art production rate.     

Archaeological applications of polynomial texture mapping: analysis,conservation and representation

Polynomial Texture Mapping is an image capture and processing technique that was developed by HP Labs in 2000. It enables the recording and representation of subtle surface details using a standard digital camera and lighting, and software that is free for non-commercial use. Cultural heritage applications have been associated with the technology from its earliest stages, including examples in areas such as cuneiform, numismatics, rock art, lithics and Byzantine art. The paper begins by outlining the technical principles involved. It then brings together the extant work in the field. Through examples developed by the University of Southampton in partnership with a range of UK and international bodies it demonstrates the benefits of the technology in the areas of archaeological analysis, conservation and representation. Finally it considers the future possibilities of this technology and ongoing developments.     

Sailing virtual canoes across Oceania: revisiting island accessibility

Understanding sailing conditions is a basic requirement for understanding the two periods of settlement of the distant islands of Oceania, initially from the Bismarck Islands off New Guinea as far as Samoa and later from Samoa throughout East Polynesia. The question of a “navigational threshold” between these two worlds is the focus of this paper. A computer simulation is presented that quantifies the difficulty of sailing virtual canoes in the differing wind conditions in both areas. The model demonstrates substantial differences in ease of voyaging up to and beyond Samoa. That this measure is so markedly different between these two worlds gives support for the hypothesised pause between the discovery and settlement of islands West and East of Samoa.     

西汉铸钱工艺中钱币型腔和内浇道对充型过程影响的计算机模拟试验

西汉时期平板范竖式浇注铸钱工艺中有不同的钱币型腔设置和内浇道的形状,本研究通过计算机的流动模拟和凝固模拟技术,研究了钱币型腔和内浇道对充型过程的影响。结果表明:1)钱币型腔的不同设置对充型时间影响不大。2)钱币型腔的不同设置对充型过程产生影响,内郭正置的型腔产生气孔等铸造缺陷的可能性增大。3)内浇道的形状对钱币型腔的液流充型时间和液流在型腔中的流动过程有明显的影响,对凝固特征虽略有影响,但远小于钱币本身几何特征对凝固特征的影响。西汉中期起至晚期已基本采用内郭斜置的型腔设置,表明古代工匠在西汉中期始已明了钱币型腔的设置对充型过程将产生影响,已能通过选择更好的钱币型腔的设置来提高钱币的铸造质量。铸钱时,对缩短充型时间的要求高于对充型状态的要求,西汉中期以后多采用缩短充型时间的内浇道形状以提高平板范竖式浇铸工艺的充满率,从而提高成品率。     

Wirtschaftswunder in Pretzfeld,upper Franconia: Interactions between science,technology, and corporate strategies in Siemens semiconductor rectifier research & development, 1945–1956

Abstract

Immediately after World War II, when emergency production of non‐electrotechnical products such as stoves, pots, etc. at Siemens amounted to more than 50% and the return to normal production and old standards was the primary company goal, one man, Eberhard Spenke, thought far ahead. Power semiconductor rectifiers were to be designed and manufactured on a scientific basis rather than as a result of trial and error methods. The theory of rectification in semiconductor‐metal contacts that had been found by the Siemens theoretical physicist Walter H. Schottky was to serve as a starting point. First, apartments for researchers had to be built in a former stable at Pretzfeld Castle, Upper Franconia; lab equipment was then procured. On September 1, 1947, research work began, and the first selenium rectifiers were made on three old kitchen tables. In 1956, Spenke proudly presented the world's first reproducible silicon power rectifier elements (for a reverse voltage of 1000 V and a maximum forward current of 300 A when forced‐air‐cooled) at the international semiconductor conference in Garmisch‐Partenkirchen, Bavaria. Siemens had thus become a world leader in power electronics.

The example of Eberhard Spenke and his team can give valuable guidelines for organizing Research & Development efficiently within a big corporation. It shows that the amount of money spent on R&D is not necessarily the determining factor of success. At least equally important are such elements as personal leadership in small research groups rather than bureaucratic administration of research, the ability to foresee technological and market developments, direct contacts between the leading researchers and the top management, open‐mindedness of the top management to new ideas and approaches, and the motivation of employees.